Effect of isocaloric low-fat diet on human LAPC-4 prostate cancer xenografts in severe combined immunodeficient mice and the insulin-like growth factor axis.

Over-consumption of dietary fat has been suggested to promote the development and progression of prostate cancer in men. The present study was conducted to answer the following questions: (a) Can dietary fat reduction decrease tumor growth rates of Los Angeles prostate cancer (LAPC)-4 xenografts in severe combined immunodeficient (SCID) mice independent of total caloric intake? and (b) Is the insulin-like growth factor (IGF) axis involved in the effects of dietary fat on LAPC-4 tumor growth in SCID mice? Twenty-eight male CB17 beige SCID mice (8 weeks old) were individually caged, randomized, and fed an isocaloric high-fat (HF, 42% kcal) or low-fat (LF, 12% kcal) diet. Each mouse was s.c. injected with 1 x 10(5) LAPC-4 cells, and tumor volumes were measured weekly. At week 16, all animals were sacrificed, and serum and tumors were obtained for analysis. Although caloric intakes and mouse weights were equal between groups, the LF mice had significantly slower tumor growth rates and lower serum prostate-specific antigen levels compared with the HF mice. LF mice had significantly lower levels of serum insulin, tumor IGF-1 mRNA expression, and tumor IGFBP-2 immunostaining and higher levels of serum IGFBP-1 (by Western ligand blot) relative to the HF mice. There were no differences in the serum levels of IGFBP-3 and IGFBP-4 between the groups. LAPC-4 cells cultured in vitro with media containing serum from LF mice demonstrated slower growth than LAPC-4 cells cultured in media containing HF mice serum. These results demonstrate that intake of an LF diet was associated with slower LAPC-4 prostate tumor growth relative to mice fed an HF diet, independent of total caloric intake, and this effect may be mediated through modulation of the insulin/IGF axis.     

Effect of low-fat diet on development of prostate cancer and Akt phosphorylation in the Hi-Myc transgenic mouse model

This study evaluated the effect of dietary fat on prostate cancer development by using the Hi-Myc mouse transgenic prostate cancer model. Hi-Myc mice develop murine prostatic intraepithelial neoplasia (mPIN) as early as 2 to 4 weeks and invasive adenocarcinoma between 6 and 9 months due to the overexpression of human c-Myc in the mouse prostate. Three-week-old male Hi-Myc mice were placed on high-fat (HF; 42% Kcal) or low-fat (LF; 12% Kcal) diets, and equal caloric intake was maintained until euthanasia at 7 months. The number of mice that developed invasive adenocarcinoma at 7 months was 27% less in the LF diet group (12/28) compared with the HF diet group (23/33, P < 0.05). Epithelial cells in mPIN lesions in the LF group had a significantly lower proliferative index compared with epithelial cells in the HF group (21.7% versus 28.9%, P < 0.05). During the mPIN phase of carcinogenesis (4 months), the LF group had higher serum insulin-like growth factor (IGF) binding protein-1 levels (21.0 +/- 8.9 ng/mL versus 3.2 +/- 0.8 ng/mL, P < 0.05) relative to the HF group. Akt (Ser(473)) phosphorylation, Akt kinase activity, and phosphorylation of downstream targets of Akt in prostates were significantly reduced in the LF diet group compared with the HF group. We conclude that dietary fat reduction delays transition from mPIN to invasive cancer in this Myc-driven transgenic mouse model, possibly through suppression of the IGF-Akt pathway and decreased proliferation of mPIN epithelial cells.     

Evidence for clonal outgrowth of androgen-independent prostate cancer cells from androgen-dependent tumors through a two-step process.

Prostate cancers require androgen for growth but progress to an androgen-independent stage under the selective pressure of androgen ablation therapy. Here we describe a novel human prostate cancer xenograft (LAPC-9) propagated by serial passage in male severe combined immunodeficient mice that expresses prostate-specific antigen and wild-type androgen receptor. In response to castration, LAPC-9 cells undergo growth arrest and persist in a dormant, androgen-responsive state for at least 6 months. After prolonged periods of androgen deprivation, spontaneous androgen-independent outgrowths develop. Thus, prostate cancers progress to androgen independence through two distinct stages, initially escaping dependence on androgen for survival and, subsequently, for growth. Through the use of serial dilution and fluctuation analysis, we provide evidence that the latter stage of androgen independence results from clonal expansion of androgen-independent cells that are present at a frequency of about 1 per 10(5)-10(6) androgen-dependent cells. We conclude that prostate cancers contain heterogeneous mixtures of cells that vary in their dependence on androgen for growth and survival and that treatment with antiandrogen therapy provides selective pressure and alters the relative frequency of these cells, thereby leading to outgrowths of androgen-independent cancers.     

An antibody targeting the type I insulin-like growth factor receptor enhances the castration-induced response in androgen-dependent prostate cancer.

PURPOSE: To determine the effect of inhibition of insulin-like growth factor-IR (IGF-IR) signaling with an antibody to the IGF-IR, A12, in conjunction with androgen withdrawal on prostate cancer progression in a human prostate xenograft model, LuCaP 35. EXPERIMENTAL DESIGN: LuCaP 35 was implanted s.c. in severe combined immunodeficient mice. At the time of castration, mice were randomized to one of three groups. Group 1 was castrate only; group 2 received A12 40 mg/kg i.p. for 2 weeks beginning 1 week after castration; and group 3 received A12 40 mg/kg i.p. for 2 weeks beginning 2 weeks after castration. RESULTS: In group 1, tumor volume decreased to 60% of the starting volume 4 weeks post-castration. In groups 2 and 3, tumor volumes nadired 6 weeks after castration at <10% of the volume at time of castration (P < 0.01). Tumor regrowth was not seen in groups 2 or 3 until 15 weeks after castration. Androgen receptor (AR) localization in tumors showed a decrease in nuclear staining in groups 2 and 3 compared with group 1 (P < 0.001). Tumor volume correlated with nuclear AR intensity. AR-regulated genes increased early in group 1, but did not increase in groups 2 and 3. Thus, tumor-specific survival was prolonged by the addition of A12 to castration. Conclusions: This study shows that the inhibition of IGF-IR enhances the effects of castration in prostate cancer. These effects are associated with a decrease in AR signaling and nuclear AR localization, and recurrence is associated with an increase in AR-regulated gene expression.     

5-aza-2'-deoxycytidine delays androgen-independent disease and improves survival in the transgenic adenocarcinoma of the mouse prostate mouse model of prostate cancer.

PURPOSE: We have previously shown that 5-aza-2'-deoxycytidine (5-aza) is an effective chemopreventive agent capable of preventing early disease progression in the transgenic adenocarcinoma of the mouse prostate (TRAMP) model. The purpose of this study was to determine the effect of 5-aza on preexisting TRAMP prostate cancers and prevention of androgen-independent prostate cancer. EXPERIMENTAL DESIGN: TRAMP mice with established prostate cancers were treated with 5-aza, castration, castration + 5-aza, or vehicle control (PBS). One cohort of 22 mice per treatment was euthanized after 10 weeks of treatment, whereas a second cohort of 14 mice per group was followed until death to determine survival. Histologic sections of prostate, pelvic lymph nodes, lung, and liver were blinded and analyzed by a certified genitourinary pathologist (K.J.W.). RESULTS: Combined treatment (castration + 5-aza) provided significant survival benefits over either single treatment (combined versus castration P = 0.029, combined versus 5-aza P = 0.036). At 24 weeks of age, 86% of mice within the PBS cohort exhibited histologic evidence of prostate cancer, whereas only 47% of the combined cohort exhibited malignant disease (P < 0.0001). Additionally, whereas 43% of the PBS treatment group exhibited lymph node metastases, these were only observed in 21% of the combined treatment mice. CONCLUSIONS: This is the first study to examine the effect of 5-aza and combined castration + 5-aza on preexisting prostate cancer in an animal model. Based on these preclinical findings, we suggest that 5-aza treatment may prolong the time to an androgen-independent status and thus survival in a hormone-deprived setting in prostate cancer.     

Angiogenesis, microvascular architecture, microhemodynamics, and interstitial fluid pressure during early growth of human adenocarcinoma LS174T in SCID mice.

To date, most quantitative information on tumor angiogenesis, microcirculation, and transport has been derived from rodent tumors grown in transparent chamber preparations. In this paper we present a chamber technique adapted to immunodeficient mice for the study of human tumor xenografts. Microcirculatory parameters in severe combined immunodeficient mice bearing a dorsal skin fold chamber preparation were quantified using intravital microscopy and image analysis. The take rate of the human colon adenocarcinoma LS174T in the chamber preparation was 100%, and the tumor area doubling time was 6.5 days. Three days following implantation of 2 x 10(5) tumor cells onto the striated skin muscle, capillary sprouts were noted in the tumor cell mass. Microvasculature in the tumors was established after 10 days. Capillary density, vessel diameter, red blood cell velocity, and blood flow rates in individual microvessels measured on days 10, 14, 18, and 22 showed no statistical difference in the striated muscle (capillaries) and subcutaneous tissue (arterioles and venules) of the skin of tumor-free animals (N = 6), whereas these parameters increased slightly, but not significantly, in the LS174T tumors (N = 7). Mean interstitial fluid pressure (+/- SD) in these small tumors was 4.6 +/- 1.7 mmHg (N = 4) on day 10 and 5.1 +/- 0.9 mmHg (N = 4) on day 22 and significantly elevated compared to that in the subcutaneous and skin tissue (-0.9 +/- 0.8 mmHg) (N = 4) (P < 0.001). To our knowledge, this is the first model enabling intravital microscopic studies of human tumor xenografts in a transparent chamber preparation in severe combined immunodeficient mice. Studies on angiogenesis, microcirculation, and transport using such a preparation should provide new insights into microcirculation-mediated mechanisms for cancer treatment.     

Effect of altering dietary omega-6/omega-3 fatty acid ratios on prostate cancer membrane composition, cyclooxygenase-2, and prostaglandin E2.

PURPOSE: To determine whether altering the dietary content of omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids affects the growth of androgen-sensitive prostate cancer xenografts, tumor membrane fatty acid composition, and tumor cyclooxygenase-2 and prostaglandin E(2) (PGE(2)) levels. EXPERIMENTAL DESIGN: Individually caged male severe combined immunodeficiency mice were fed isocaloric 20% kcal fat diets with the fat derived either primarily from n-6 fatty acids (n-6 group) or with the fat consisting of n-6 and n-3 fatty acids in a ratio of 1:1 (n-3 group), and injected s.c. with Los Angeles Prostate Cancer 4 (LAPC-4) cells. Tumor volumes and mouse weights were measured weekly, caloric intake was measured 3 days per week, and tumors and serum were harvested at 8 weeks postinjection. RESULTS: Tumor growth rates, final tumor volumes, and serum prostate-specific antigen levels were reduced in the n-3 group relative to the n-6 group. The n-3 group tumors had decreased proliferation (Ki67 staining) and increased apoptosis (terminal nucleotidyl transferase-mediated nick end labeling staining). In vitro proliferation of LAPC-4 cells in medium containing n-3 group serum was reduced by 22% relative to LAPC-4 cells cultured in medium containing serum from the n-6 group. The n-6/n-3 fatty acid ratios in serum and tumor membranes were lower in the n-3 group relative to the n-6 group. In addition, n-3 group tumors had decreased cyclooxygenase-2 protein and mRNA levels, an 83% reduction in PGE(2) levels, and decreased vascular endothelial growth factor expression. CONCLUSION: These results provide a sound basis for clinical trials evaluating the effect of dietary n-3 fatty acids from fish oil on tumor PGE(2) and membrane fatty acid composition, and serum and tumor biomarkers of progression in men with prostate cancer.     

Antiangiogenic treatment with the three thrombospondin-1 type 1 repeats recombinant protein in an orthotopic human pancreatic cancer model.

PURPOSE: This study investigates the antiangiogenesis and antitumor efficacy of a recombinant protein composed of the three type 1 repeats (3TSR) of thrombospondin-1 in an orthotopic human pancreatic cancer model and provides useful preclinical data for pancreatic cancer treatment. EXPERIMENTAL DESIGN: Human pancreatic cancer cells (AsPC-1) were injected into the pancreas of severe combined immunodeficient mice. The animals were treated with 3TSR (3 mg per kg per day) or PBS for 3 weeks. Subsequently, the effects of 3TSR on tumor growth, microvessel density, cancer cell proliferation, apoptosis, and endothelial cell apoptosis were analyzed. The in vitro effects of 3TSR on human pancreatic cancer cells were also studied. RESULTS: 3TSR treatment significantly reduced angiogenesis and tumor growth of orthotopic pancreatic cancer. 3TSR-treated mice had a 69% reduction in tumor volume (316.6 +/- 79.3 versus 1,012.2 +/- 364.5 mm(3); P = 0.0001), and a significant increase in tumor necrotic area. After 3TSR treatment, both the vessel number and average microvessel size were significantly decreased, and microvessel density was decreased from 8.0% to 3.7% (P < 0.0001). The apoptotic rate of tumoral endothelial cells in 3TSR-treated tumors increased to 14.7% comparing to 4.2% in control tumors (P < 0.0001). 3TSR showed no direct effects on pancreatic cancer cell proliferation or apoptosis either in vivo or in vitro. CONCLUSION: 3TSR, a domain of a natural occurring angiogenesis inhibitor, showed potent therapeutic effect in pancreatic cancer by inhibiting tumor angiogenesis and may prove to be a promising agent for clinical pancreatic cancer treatment.     

高脂饮食对结肠癌肝脏转移的影响及作用机制

目的 探讨高脂饮食对结肠癌肝脏转移的影响及其作用机制。方法 30只NSI第三代免疫缺陷裸鼠脾脏种植结肠癌细胞DLD1构建移植瘤裸鼠模型,分别喂养普通饲料（对照组）、高脂饲料（高脂饮食组）和高脂饲料并腹腔注射CXCR4拮抗剂AMD3100（高脂饮食+AMD3100组）,每组10只。12周后颈椎脱臼处死,称量各组裸鼠体重、肝脏重量,统计肝脏中肿瘤转移灶数目,并采用Western blot和RT-qPCR检测肿瘤组织中SDF-1、CXCR4的蛋白和mRNA表达水平。结果 12周后,高脂饮食组裸鼠体重、脂肪重量、肝脏重量及血清瘦素浓度高于对照组和高脂饮食+AMD3100组（P<0.05）。对照组、高脂饮食组和高脂饮食+AMD3100组裸鼠发生肝脏转移的比例分别为30.0%、80.0%和40.0%。高脂饮食组裸鼠的肿瘤体积及肝脏转移灶数量均明显高于对照组［（3.83±0.42） mm³  vs （1.00±0.15） mm³,P<0.001;（4.33±0.58） 个 vs （1.33±0.58） 个,P=0.002］和高脂饮食+AMD3100组 ［（3.83±0.42） mm³  vs （1.96±0.15） mm³,P<0.001;（4.33±0.58） 个 vs （2.33±0.58） 个,P=0.002］。Western blot和RT-qPCR检测结果显示,高脂饮食组结肠癌组织中的SDF-1、CXCR4的蛋白和mRNA表达水平均较对照组和高脂饮食+AMD3100组明显上调（均P<0.05）。结论 高脂饮食可通过促进结肠癌癌组织中SDF-1和CXCR4的表达水平而增强结肠癌的肝脏定向转移。     

Increased susceptibility of Sf1(+/-) mice to azoxymethane-induced colon tumorigenesis

Aberrant transactivation of a certain set of target genes by the beta-catenin and T-cell factor-4 nuclear complex has been considered crucial for the initiation of colorectal carcinogenesis. We previously identified splicing factor-1 (SF1) as a novel component of the beta-catenin and T-cell factor-4 complex, and showed that the overexpression of SF1 inhibited the gene transactivational activity of the complex and markedly suppressed beta-catenin-evoked colony formation by human embryonic kidney 293 cells. However, the involvement of SF1 in the process of carcinogenesis in vivo remains unclear. In the present study, we established SF1-knockout mice using the gene trapping method. Homozygous mice (Sf1(-/-)) died during embryonic development before embryonic day (E)8.5, whereas heterozygous (Sf1(+/-)) mice were born alive and developed normally. Azoxymethane (AOM) was given at a dose of 10 mg/kg body weight once a week for 6 weeks to 7-week-old Sf1(+/-) and Sf1(+/+) mice. At 23 weeks after the start of AOM the average number (5.5 +/- 0.6 versus 2.2 +/- 0.2 in females [P = 0.003, Mann-Whitney U-test], 3.7 +/- 0.2 versus 1.7 +/- 0.7 in males [P = 0.014]) and volume of colon tumors per mouse (8.7 +/- 1.6 versus 2.2 +/- 0.5 mm(3) per female [P = 0.0008], 11.3 +/- 3.4 versus 0.6 +/- 0.2 mm(3) per male [P = 0.001]) were significantly higher in Sf1(+/-) than in Sf1(+/+) mice. The increased susceptibility of Sf1(+/-) mice to AOM-induced colon tumorigenesis indicates the crucial involvement of SF1 in the beta-catenin-mediated regulation of proliferation and differentiation of intestinal epithelial cells.     

In vivo antitumor activity of bis(4,7-dimethyl-1,10-phenanthroline) sulfatooxovanadium(IV) (METVAN [VO(SO4)(Me2-Phen)2]).

The compound bis(4,7-dimethyl-1,10-phenanthroline) sulfatooxovanadium(IV) (METVAN [VO(SO4)(Me2-Phen)2]), exhibits potent cytotoxicity against human cancer cells at low micromolar concentrations. At concentrations > or = 1 microM, METVAN treatment was associated with a nearly complete loss of the adhesive, migratory, and invasive properties of the treated tumor cell populations. METVAN did not cause acute or subacute toxicity in mice at dose levels ranging from 12.5 mg/kg to 100 mg/kg. Therapeutic plasma concentrations > or = 5 microM were rapidly achieved and maintained in mice for at least 24 h after i.p. bolus injection of a single 10 mg/kg nontoxic dose of METVAN. At this dose level, the maximum plasma METVAN concentration was 37.0 microM, which was achieved with a t(max) of 21.4 min. Plasma samples (diluted 1:16) from METVAN-treated mice killed 85% of human breast cancer cells in vitro. METVAN was slowly eliminated with an apparent plasma t(1/2) of 17.5 h and systemic clearance of 42.1 ml/h/kg. In accordance with its potent in vitro activity and favorable in vivo pharmacokinetics, METVAN exhibited significant antitumor activity and delayed tumor progression in CB.17 severe combined immunodeficient (SCID) mouse xenograft models of human glioblastoma and breast cancer. In these experiments, METVAN was administered in daily injections of a single nontoxic 10 mg/kg i.p. dose on 5 consecutive days per week for 4 consecutive weeks beginning the day after the s.c. inoculation of U87 glioblastoma or MDA-MB-231 breast cancer cells. At 40 days after the inoculation of tumor cells, the U87 tumor xenografts in the vehicle-treated control SCID mice were much larger than those of the mice treated with METVAN (4560 +/- 654 mm(3) versus 1688 +/- 571 mm(3); P = 0.003). Similarly, the MDA-MB-231 tumors in SCID mice treated with METVAN were much smaller 40 days after tumor cell inoculation than those of the vehicle-treated control SCID mice (174 +/- 29 mm(3) versus 487 +/- 82 mm(3); P = 0.002). The favorable in vivo pharmacodynamic features and antitumor activity of METVAN warrants further development of this novel oxovanadium compound as a potential new anticancer agent.     

Early therapy evaluation of combined anti-death receptor 5 antibody and gemcitabine in orthotopic pancreatic tumor xenografts by diffusion-weighted magnetic resonance imaging

Early therapeutic efficacy of anti-death receptor 5 antibody (TRA-8) combined with gemcitabine was measured using diffusion-weighted magnetic resonance imaging (DWI) in an orthotopic pancreatic tumor model. Groups 1 to 4 of severe combined immunodeficient mice (n = 5-7 per group) bearing orthotopically implanted, luciferase-positive human pancreatic tumors (MIA PaCa-2) were subsequently (4-5 weeks thereafter) injected with saline (control), gemcitabine (120 mg/kg), TRA-8 (200 mug), or TRA-8 combined with gemcitabine, respectively, on day 0. DWI, anatomic magnetic resonance imaging, and bioluminescence imaging were done on days 0, 1, 2, and 3 after treatment. Three tumors from each group were collected randomly on day 3 after imaging, and terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling staining was done to quantify apoptotic cellularity. At just 1 day after starting therapy, the changes of apparent diffusion coefficient (ADC) in tumor regions for group 3 (TRA-8) and group 4 (TRA-8/Gem) were 21 +/- 9% (mean +/- SE) and 27 +/- 3%, respectively, significantly higher (P < 0.05) than those of group 1 (-1 +/- 5%) and group 2 (-2 +/- 4%). There was no statistical difference in tumor volumes for the groups at this time. The mean ADC values of groups 2 to 4 gradually increased over 3 days, which were concurrent with tumor volume regressions and bioluminescence signal decreases. Apoptotic cell densities of tumors in groups 1 to 4 were 0.7 +/- 0.4%, 0.6 +/- 0.2%, 3.1 +/- 0.9%, and 4.7 +/- 1.0%, respectively, linearly proportional to the ADC changes on day 1. Further, the ADC changes were highly correlated with the previously reported mean survival times of animals treated with the same agents and doses. This study supports the clinical use of DWI for pancreatic tumor patients for early assessment of drug efficacy.     

Establishment of a human t(4;11) leukemia in severe combined immunodeficient mice and successful treatment using anti-CD19 (B43)-pokeweed antiviral protein immunotoxin.

Human acute leukemia, with a chromosomal translocation involving chromosomes 4 and 11, t(4;11)(q21;q23), is the most common form of leukemia in infants and responds very poorly to conventional therapy. A human CD19+ mixed-lineage leukemia cell line with a t(4;11)(q21;q23) translocation, RS4;11, disseminated and proliferated in the hematopoietic tissues and other organs of mice with severe combined immunodeficiency in a manner similar to that observed in humans and killed 100% of the animals. The anti-CD19(B43)-pokeweed antiviral protein immunotoxin selectively inhibited clonogenic RS4;11 cells in vitro, markedly reduced the burden of disseminated leukemia of severe combined immunodeficient mice, and, most importantly, resulted in the long-term survival of treated animals. This severe combined immunodeficient mouse model should be useful for the design of more effective treatment strategies for refractory human leukemias.     

Mechanisms in the chemoprevention of colon cancer: modulation of protein kinase C, tyrosine protein kinase and diacylglycerol kinase activities by 1,4-phenylenebis-(methylene)selenocyanate and impact of low-fat diet

Epidemiological and experimental studies suggest an inverse relationship between the intake of dietary selenium and/or low fat-intake and colon cancer risk. Efficacy studies in rodents suggest that the organoselenium compound 1, 4-phenylenebis(methylene)selenocyanate (p-XSC), is a more effective and less toxic chemopreventive agent than other organic or inorganic selenium compounds such as selenomethionine and Na2SeO3. The efficacy of p-XSC against colon cancer is significantly augmented by a low-fat diet. To explore the mechanisms by which this combined inhibiting effect against colon carcinogenesis comes about, we have investigated protein kinase C (PKC), tyrosine protein kinase (TPK), diacylglycerol kinase (DGK) activities and 8-isoprostane levels in colonic mucosa and tumor tissues in an azoxymethane (AOM)-induced rat colon cancer model. Weanling male F344 rats were fed the semipurified AIN-76A diet until seven weeks of age. Then various experimental groups were fed the low- or high-fat diets containing 0 or 20 ppm p-XSC (10 ppm as selenium). At seven weeks of age, groups of rats were injected s.c. with azoxymethane (AOM; 15 mg/kg body wt., once weekly for 2 weeks) and continued on their respective experimental diets until 38 weeks after the second AOM treatment. They were then sacrificed and colonic mucosal and tumor samples were evaluated for PKC, TPK, DGK and 8-isoprostane levels. Administration of p-XSC along with a low-fat diet significantly inhibited Ca+2-dependent and -independent PKC (P<0.05-0.01) activities in colonic mucosa and tumors. Administration of p-XSC either low-fat or high-fat diet significantly suppressed both colonic mucosal and tumor TPK activity (P<0.05-0.01). Suppression of TPK activity was more pronounced in rats maintained on a low-fat diet containing p-XSC. In contrast, rats receiving p-XSC with either low- or high fat diet showed significantly increased DGK activity (P<0.01-0.0001). Rats fed low-fat or high-fat plus p-XSC had lower-levels of 8-isoprostane in the colonic tumors than animals who had been given low- or high-fat diets without the organoselenium compound. Interestingly, 8-isoprostane levels were lower in the colon tumors of the rats fed the low-fat diet than those fed the high-fat diet. Our findings suggest that p-XSC induced down-regulation of PKC and TPK activities and up-regulation of DGK activity. These events may in part be responsible for the chemopreventive activity against colon carcinogenesis. Further, this study implies that p-XSC with a low-fat dietary regimen will augment regulation of PKC, TPK and DGK activities in the colon.     

Squamous cell carcinoma of the oropharynx: surgery,radiation therapy,or both

BACKGROUND: The treatment of patients with squamous cell carcinoma (SCC) of the oropharynx remains controversial. No randomized trial has addressed adequately the question of whether surgery (S), radiation therapy (RT), or combined treatment is most effective. METHODS: Treatment results from North American academic institutions that used S with or without adjuvant RT (S +/- RT) or used RT alone or followed by neck dissection (RT +/- ND) for patients with SCC of the tonsillar region or the base of tongue were compiled through a MEDLINE search (from 1970 to August, 2000) and from the references cited in each report. Studies were eligible for inclusion if they contained direct, actuarial (life-table), or Kaplan-Meier calculations for the following end points: local control, local-regional control, 5-year absolute survival, 5-year cause specific survival, or severe or fatal treatment complications. Weighted average results, which took into account series size, were calculated for each end point for the purposes of treatment comparison. Results and conclusions were based on data from 51 reported series, representing the treatment of approximately 6400 patients from the United States and Canada. RESULTS: The results for patients with SCC of the base of tongue who underwent S +/- RT versus RT +/- ND, respectively, were as follows: local control, 79% versus 76% (P = 0.087); local-regional control, 60% versus 69% (P = 0.009); 5-year survival, 49% versus 52% (P = 0.2); 5-year cause specific survival, 62% versus 63% (P = 0.4); severe complications, 32% versus 3.8% (P < 0.001); and fatal complications, 3.5% versus 0.4% (P < 0.001). The results for patients with SCC in the tonsillar region who underwent S +/- RT versus RT +/- ND, respectively, were as follows: local control, 70% versus 68% (P = 0.2); local-regional control, 65% versus 69% (P = 0.1); 5-year survival, 47% versus 43% (P = 0.2); 5-year cause specific survival, 57% versus 59% (P = 0.3); severe complications, 23% versus 6% (P < 0.001); and fatal complications, 3.2% versus 0.8% (P < 0.001). CONCLUSIONS: The information in this article provides a useful benchmark for evidence-based counseling of patients with SCC of the oropharynx. The rates of local control, local-regional control, 5-year survival, and 5-year cause specific survival were similar for patients who underwent S +/- RT or RT +/- ND, whereas the rates of severe or fatal complications were significantly greater for the S +/- RT group. Furthermore, available data on the functional consequences of treatment suggest the superiority of RT +/- ND. The authors conclude that RT +/- ND is preferable for the majority of patients with SCC of the oropharynx.     

Improved outcome when B-cell lymphoma is treated with combinations of immunoliposomal anticancer drugs targeted to both the CD19 and CD20 epitopes.

PURPOSE: We have reported previously that successful immunoliposomal drug therapy with liposomal doxorubicin (DXR) against xenograft B-lymphoma models required targeting against an internalizing B-cell antigen, CD19 (P. Sapra and T. M. Allen. Cancer Res 2002;62:7190-4.). Here we compare targeting of immunoliposomal formulations of DXR with vincristine (VCR) targeted against CD19 versus a noninternalizing (CD20) epitope. We also examine the effect of targeting immunoliposomes with antibody combinations in an attempt to increase the total number of binding sites (apparent antigen density) at the target cell surface. EXPERIMENTAL DESIGN: Cell association of immunoliposomes (CD19-targeted, CD20-targeted, or combinations of the two) with human B-cell lymphoma (Namalwa) cells were studied using radiolabeled liposomes. Therapeutic efficacy of the same formulations was determined in a severe combined immunodeficient murine model. RESULTS: Therapeutic results in severe combined immunodeficient mice bearing Namalwa cells administered anti-CD20-targeted liposomal DXR were barely improved over those found for nontargeted liposomal DXR or free DXR but, surprisingly, administration of anti-CD20-targeted liposomal VCR resulted in a significantly improved therapeutic outcome compared with nontargeted liposomal VCR, free VCR, or anti-CD20-targeted liposomal DXR. Treatment of murine B lymphoma with single injections of combinations of anti-CD19- and anti-CD20-targeted liposomal VCR led to cures in 70% of mice. However, mice injected with similar combinations of liposomal DXR did not have improved survival rates over anti-CD19-targeted liposomal DXR by itself. CONCLUSIONS: The success of immunoliposomal therapy in combination regimens varies with the type of encapsulated drug and the nature of the target epitopes.     

Beef induces and rye bran prevents the formation of intestinal polyps in Apc(Min) mice: relation to beta-catenin and PKC isozymes

Epidemiological studies suggest that high consumption of red meat and saturated fat and low consumption of fiber are associated with an increased risk of colon cancer. Therefore, we studied whether diets high in red meat or high in different grain fibers as well as inulin, polydisperse beta(2-->1) fructan, could affect the formation of intestinal polyps in Apc(Min) mice. Min mice were fed the following high-fat (40% of energy) diets for 5-6 weeks; a high-beef diet and a casein-based diet without added fiber or casein-based diet with 10% (w/w) oat, rye or wheat bran, or 2.5% (w/w) inulin. One group had a normal low-fat AIN93-G diet. The mice fed the rye-bran diet had the lowest number of polyps in the distal small intestine [15.4 +/- 8.7 (mean +/- SD)], and in the entire intestine (26.4 +/- 12.1). The rye-bran group differed significantly (P = 0. 001-0.004) from the beef group (36.6 +/- 9.4 and 52.8 +/- 13.2). In addition, the beef group differed significantly from the AIN93-G group (P = 0.009) and also from the wheat-bran group (21.0 +/- 6.1 and 35.0 +/- 8.2; P = 0.02) in the distal small intestine. The inulin group (32.9 +/- 14.3 and 49.3 +/- 16.3), on the other hand, was close to the beef group and it differed significantly from the rye-bran group in the distal small intestine. The number of animals bearing tumors in the colon + caecum was only 33% in the rye-bran group when compared with 89% in the beef and 100% in the inulin groups. The mice fed the rye-bran and beef diets had the lowest levels of cytosolic beta-catenin (0.60 +/- 0.42 and 0.67 +/- 0.26) and they differed significantly (P = 0.040 and 0.062) from the mice fed the oat-bran diet (1.46 +/- 0.43). No differences between groups in expression of protein kinase C (PKC) alpha, betaII, delta and zeta were found. The four PKC isozymes were positively correlated with cytosolic beta-catenin levels (r = 0.62-0.68; P < 0.0001).     

Enhanced killing of primary ovarian cancer by retargeting autologous cytokine-induced killer cells with bispecific antibodies: a preclinical study.

Cytokine-induced killer (CIK) cells are ex vivo activated and expanded CD8+ natural killer T cells that have been shown to have antitumor activity. This is the first study exploring cell killing of primary ovarian carcinoma cells with and without bispecific antibodies. Primary cancer cells and autologous CIK cells were collected from women with epithelial ovarian cancer. Bispecific antibodies against cancer antigen-125 (BSAbxCA125) and Her2 (BSAbxHer2) were developed using chemical heteroconjugation. On fluorescence-activated cell sorting analysis, the expansion of CIK cells resulted in a significant increase of CD3+CD8+ and CD3+CD56+ T cells. With enhancement by bispecific antibodies, the mean percent lysis in a 51Cr release assay of fresh ovarian cancer cells exposed to autologous CIK cells increased from 21.7 +/- 0.3% to 89.4 +/- 2.1% at an E:T ratio of 100:1 (P < 0.001). Anti-NKG2D antibodies attenuated the CIK activity by 56.8% on primary cells (P < 0.001). In a xenograft severe combined immunodeficient mouse model, real-time tumor regression and progression was visualized using a noninvasive in vivo bioluminescence imaging system. Four hours after CIK cell injection, we were able to visualize CD8+NKG2D+ CIK cells infiltrating Her2-expressing cancer cells on fluorescence microscopy. Mice that underwent adoptive transfer of CIK cells redirected with BSAbxCA125 and BSAbxHer2 had significant reduction in tumor burden (P < 0.001 and P < 0.001) and improvement in survival (P = 0.05 and P = 0.006) versus those treated with CIK cells alone. Bispecific antibodies significantly enhanced the cytotoxicity of CIK cells in primary ovarian cancer cells and in our in vivo mouse model. The mechanism of cytolysis seems to be mediated in part by the NKG2D receptor.     

Effects of dietary fat and a vegetable-fruit mixture on the development of intestinal neoplasia in the ApcMin mouse

The variation in colorectal cancer (CRC) incidence worldwide strongly suggests a role for dietary influences. Based on epidemiological data, protective effects of vegetables and fruit intake on CRC are widely claimed, while other data indicate a possible increased CRC risk from (higher) dietary fat intake. Therefore, we have investigated single and interactive effects of dietary fat and a vegetable-fruit mixture (VFM) in the ApcMin mouse, a mouse model for multiple intestinal neoplasia. In this study, four different diets (A-D) were compared, which were either low in fat (20% energy diets A/B) or high in fat (40% energy diets C/D). In addition, 19.5% (wt/wt) of the carbohydrates in diets B and D were replaced by a freeze-dried VFM. The diets were balanced so that they only differed among each other in fat/carbohydrate content and the presence of specific plant-constituents. Because the initiation of intestinal tumors in ApcMin mice occurs relatively early in life, exposure to the diets was started in utero. Without the addition of VFM, mice maintained at a high-fat diet did not develop significantly higher numbers of small or large intestinal adenomas than mice maintained at a low-fat diet. VFM added to a low-fat diet significantly lowered multiplicity of small intestinal polyps (from 16.2 to 10.2/mouse, 15 animals/group), but not of colon tumors in male ApcMin mice only. Strikingly, addition of VFM to female mice maintained on a low-fat diet and to both sexes maintained on a high-fat diet significantly enhanced intestinal polyp multiplicity (from 16.5 to 26.7 polyps/mouse). In conclusion, our results indicate that neither a lower fat intake nor consumption of VFM included in a high-fat diet decreases the development of polyps in mice genetically predisposed to intestinal tumor development.      

Genetic ablation of M3 muscarinic receptors attenuates murine colon epithelial cell proliferation and neoplasia

Colon epithelial cells express and most colon cancers overexpress M(3) muscarinic receptors (M(3)R). In human colon cancer cells, post-M(3)R signaling stimulates proliferation. To explore the importance of M(3)R expression in vivo, we used the azoxymethane-induced colon neoplasia model. Mice treated with weekly i.p. injection of saline [10 wild-type (WT) mice] or azoxymethane (22 WT and 16 M(3)R(-/-) mice) for 6 weeks were euthanized at 20 weeks. At week 20, azoxymethane-treated WT mice weighed approximately 16% more than M(3)R(-/-) mice (33.4 grams +/- 1.0 grams versus 27.9 grams +/- 0.5 grams; mean +/- SE, P < 0.001). In azoxymethane-treated M(3)R(-/-) mice, cell proliferation (BrdUrd staining) was reduced 43% compared with azoxymethane-treated WT mice (P < 0.05). Whereas control mice (both WT and M(3)R(-/-)) had no colon tumors, azoxymethane-treated WT mice had 5.3 +/- 0.5 tumors per animal. Strikingly, azoxymethane-treated M(3)R(-/-) mice had only 3.2 +/- 0.3 tumors per mouse (P < 0.05), a 40% reduction. Tumor volume in azoxymethane-treated M(3)R(-/-) mice was reduced 60% compared with azoxymethane-treated WT mice (8.1 mm(3) +/- 1.5 mm(3) versus 20.3 mm(3) +/- 4.1 mm(3); P < 0.05). Compared with WT, fewer M(3)R(-/-) mice had adenomas (6% versus 36%; P = 0.05), and M(3)R(-/-) mice had fewer adenocarcinomas per mouse (0.6 +/- 0.1 versus 1.7 +/- 0.4; P < 0.05). Eleven of 22 WT but no M(3)R(-/-) mice had multiple adenocarcinomas (P < 0.001). Compared with WT, azoxymethane-treated M(3)R-deficient mice have attenuated epithelial cell proliferation, tumor number, and size. M(3)R and post-M(3)R signaling are novel therapeutic targets for colon cancer.