Regulation of growth by a nerve growth factor-like protein which modulates paracrine interactions between a neoplastic epithelial cell line and stromal cells of the human prostate.

Nerve growth factor-like substance(s) were identified in both conditioned media of a human prostatic tumor epithelial cell line (TSU-pr1) and a human prostatic stromal cell line (HPS) by Western blot analysis and bioassay of neurite outgrowth of PC12 cells. Nerve growth factor-beta (NGF) immunofluorescence was also localized to secretory vesicles in the cytoplasm of both the TSU-pr1 and HPS cells. Western blot of the TSU-pr1 and HPS cell-secreted protein identified an Mr 65,000 major protein which immunoreacted with murine NGF antibody. NGF Western blot of HPS cell-secreted protein also identified an Mr 42,000 minor band under reduced and nonreduced conditions and an Mr 61,000 minor band under reduced conditions. The secreted protein from the TSU-pr1 cells (50 micrograms/ml) and HPS (50 micrograms/ml), as well as murine NGF (50 ng/ml) or human recombinant NGF (50 ng/ml), stimulated neurite outgrowth from PC12 cells. This neurite outgrowth activity was partially inhibited by treatment with NGF antibody. Neither the serum containing growth medium nor bovine serum albumin (50 micrograms/ml) stimulated neurite outgrowth. The NGF-like secretory protein appeared to play a role in the paracrine regulation of prostatic growth between TSU-pr1 cells and HPS cells. The relative growth of TSU-pr1 cells, as indicated by [3H]thymidine incorporation, in response to HPS secretory protein was stimulated 2.8-fold in a dose-dependent manner. In the converse interaction, the relative growth of HPS cells in response to TSU-pr1 secretory protein was stimulated 1.8-fold in a dose-dependent manner. Immunoneutralization of TSU-pr1 and HPS secretory protein was performed with antibody against NGF, acidic fibroblast growth factor, and basic fibroblast growth factor. Removal of the NGF-like protein from the maximal stimulatory dose of TSU-pr1 secretory protein (100 micrograms/ml) with NGF antibody reduced HPS proliferation to 52% of maximal levels, and immunoneutralization of the NGF-like protein in the maximal stimulatory dose of HPS secretory protein (20 micrograms/ml) also reduced TSU-pr1 proliferation to 16% of maximal levels. Addition of normal rabbit serum or prior immunoprecipitation of either TSU-pr1 or HPS secretory protein with antibody against acidic fibroblast growth factor and basic fibroblast growth factor did not inhibit the proliferation of either cell type. These results suggest that TSU-pr1 tumor cells and HPS cells secrete NGF-like protein(s) which modulate their paracrine interactive growth in vitro.     

Enhancement of osteoclastogenic activity in osteolytic prostate cancer cells by physical contact with osteoblasts

Background:

The interaction between prostate cancer cells and osteoblasts is critical for the development of bone metastasis. Metastatic cancer cells may physically contact osteoblasts in the bone microenvironment; however, the biological significance of this interaction is not fully understood.

Methods:

Human prostate cancer cells (the osteolytic cell line PC-3 and the osteoblastic cell line MDA-PCa 2b) and human osteoblasts (hFOB1.19) were cocultured under two different conditions (bilayer and contact conditions). Differential gene expression profiles of prostate cancer cells were then investigated using microarray analysis. Differentially expressed genes were analysed using RT–PCR and western blotting, and the effect of anti-cadherin neutralising antibodies on their expression was assayed. The osteoclastogenic activity of cells grown under these different conditions was also investigated using an in vitro assay.

Results:

When PC-3 or MDA-PCa 2b cells were cocultured with hFOB1.19 cells under contact conditions, the expression of eight genes was upregulated and that of one gene was downregulated in PC-3 cells compared with gene expression in bilayer culture. No differentially expressed genes were detected in MDA-PCa 2b cells. Four of the eight upregulated genes (interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2), IL-6 and the third component of complement (C3)) have already been reported to participate in osteoclastogenesis. Indeed, a cell lysate of PC-3 cells grown under contact coculture conditions significantly enhanced osteoclastogenesis in vitro (P<0.005). neutralisation of cadherin-11 with a specific antibody inhibited upregulation of COX-2 and C3 mRNA in PC-3 cells. In contrast, neutralisation of N-cadherin induced upregulation of COX-2 mRNA.

Conclusion:

Physical contact between osteolytic prostate cancer cells and osteoblasts may upregulate osteoclastogenesis-related gene expression in prostate cancer cells and enhance osteoclastogenesis. Additionally, cadherin-11 and N-cadherin are involved in this process. These data provide evidence supporting new therapies of prostate cancer bone metastasis that target direct cancer-cell-osteoblast cell–cell contact.     

Circulating insulin-like growth factors and IGF-binding proteins in PSA-detected prostate cancer: the large case-control study ProtecT

Circulating insulin-like growth factor-I (IGF-I) has been studied extensively in prostate cancer, but there is still little information about IGFs and IGF-binding proteins (IGFBP) in cancers detected by the prostate-specific antigen (PSA) test. Here, we report the findings of a U.K.-based case-control study to investigate circulating IGFs and IGFBPs in PSA-detected prostate cancer with regard to their potential associations with different cancer stages or grades. PSA testing was offered to 110,000 men aged 50 to 69 years from 2002 to 2009. Participants with an elevated level of PSA (≥3.0 ng/mL) underwent prostate biopsy and measurements of blood serum IGF-I, IGF-II, IGFBP-2, and IGFBP-3 obtained at recruitment. We found that serum levels of IGF-II (OR per SD increase: 1.16; 95% CI: 1.08-1.24; P(trend) < 0.001), IGFBP-2 (1.18; 1.06-1.31; P(trend) < 0.01) and IGFBP-3 (1.27; 1.19-1.36; P(trend) < 0.001), but not IGF-I (0.99; 0.93-1.04; P(trend) = 0.62), were associated with PSA-detected prostate cancer. After controlling for IGFBP-3, IGF-II was no longer associated (0.99; 0.91-1.08; P(trend) = 0.62) and IGF-I was inversely associated (0.85; 0.79-0.91; P(trend) < 0.001) with prostate cancer. In addition, no strong associations existed with cancer stage or grade. Overall, these findings suggest potentially important roles for circulating IGF-II, IGFBP-2, and IGFBP-3 in PSA-detected prostate cancer, in support of recent in vitro evidence. Although our findings for IGF-I agree with previous results from PSA screening trials, they contrast with positive associations in routinely detected disease, suggesting that reducing levels of circulating IGF-I might not prevent the initiation of prostate cancer but might, nonetheless, prevent its progression.     

Synthesis and antitumor properties of selenocoxib‐1 against rat prostate adenocarcinoma cells

Hormone refractory prostate cancer poses a huge problem and standard of care chemotherapy has not been very successful. We used a novel strategy to combine properties of 2 well‐studied class of compounds (selenium and COX‐2 inhibitor) and examined the resulting effectiveness against prostate cancer. Bearing in mind that sulfonamide moiety and pyrazole ring is important for the proapoptotic activity of Celecoxib, we synthesized a selenium derivative, Selenocoxib‐1, by modifying Celecoxib at position 3 of the pyrazole ring. The PAIII cells derived from a metastatic prostate tumor that arose spontaneously in a Lobund‐Wistar (LW) rat were used to examine the efficacy of Selenocoxib‐1 in vitro. In addition, human metastatic prostate cancer cells, PC‐3M, were tested for antitumor effect of Selenocoxib‐1 in vitro. The IC₅₀ in PAIII and PC‐3M cells for Selenocoxib‐1 was about 5 μM, while for Celecoxib it was more than 20 μM. Selenocoxib‐1 induced apoptosis in a dose‐dependent manner in the PAIII cells. COX‐2 expression in PAIII cells was downregulated by Celecoxib and Selenocoxib‐1 at 20 and 5 μM, respectively; the COX‐2 activity was, however, not affected by Selenocoxib‐1. Following treatment with Selenocoxib‐1, PAIII cells resulted in dose‐dependent decrease in HIF‐1α, p‐AKT and Bcl‐2 levels. A reduction in weights was observed in subcutaneous tumors produced by PAIII cells pretreated with Selenocoxib‐1 as compared to Celecoxib in LW rats. Further, following 1 week Selenocoxib‐1 treatment of PAIII tumors resulted in significant reduction of tumor weights. This study demonstrates that Selenocoxib‐1 is more effective against prostate cancer than Celecoxib.     

Reciprocal paracrine interactions between normal human epithelial and mesenchymal cells protect cellular DNA from radiation-induced damage

PURPOSE: To explore whether interactions between normal epithelial and mesenchymal cells can modulate the extent of radiation-induced DNA damage in one or both types of cells. METHODS AND MATERIALS: Human primary thyrocytes (PT), diploid fibroblasts BJ, MRC-5, and WI-38, normal human mammary epithelial cells (HMEC), and endothelial human umbilical cord vein endothelial cells (HUV-EC-C), cultured either individually or in co-cultures or after conditioned medium transfer, were irradiated with 0.25 to 5 Gy of gamma-rays and assayed for the extent of DNA damage. RESULTS: The number of gamma-H2AX foci in co-cultures of PT and BJ fibroblasts was approximately 25% lower than in individual cultures at 1 Gy in both types of cells. Reciprocal conditioned medium transfer to individual cultures before irradiation resulted in approximately a 35% reduction of the number gamma-H2AX foci at 1 Gy in both types of cells, demonstrating the role of paracrine soluble factors. The DNA-protected state of cells was achieved within 15 min after conditioned medium transfer; it was reproducible and reciprocal in several lines of epithelial cells and fibroblasts, fibroblasts, and endothelial cells but not in epithelial and endothelial cells. Unlike normal cells, human epithelial cancer cells failed to establish DNA-protected states in fibroblasts and vice versa. CONCLUSIONS: The results imply the existence of a network of reciprocal interactions between normal epithelial and some types of mesenchymal cells mediated by soluble factors that act in a paracrine manner to protect DNA from genotoxic stress.     

Genistein protects prostate cells against hydrogen peroxide-induced DNA damage and induces expression of genes involved in the defence against oxidative stress

Prostate cancer is one of the most frequent cancer types in Western societies and predominately occurs in the elderly male. The strong age-related increase of prostate cancer is associated with a progressive accumulation of oxidative DNA damage which is presumably supported by a decline of the cellular antioxidative defence during ageing. Risk of developing prostate cancer is much lower in many Asian countries where soy food is an integral part of diet. Therefore, isoflavones from soy were suggested to have chemopreventive activities in prostate cells. Here, we have investigated the hypothesis that the soy-isoflavone genistein could protect DNA of LAPC-4 prostate cells from oxidative stress-related damage by enhancing the expression of antioxidative genes and proteins. A 24 h preincubation with genistein (1-30 microM) protected cells from hydrogen peroxide-induced DNA damage, as determined by the comet assay. Analysis of two cDNA macroarrays, each containing 96 genes of biotransformation and stress response, revealed a modulated expression of 3 genes at 1 microM and of 19 genes at 10 microM genistein. Real-time PCR confirmed the induction of three genes encoding products with antioxidant activities, namely glutathione reductase (2.7-fold), microsomal glutathione S-transferase 1 (1.9-fold) and metallothionein 1X (6.3-fold), at 1-30 microM genistein. 17Beta-estradiol, in contrast, decreased the expression of metallothionein 1X at 0.3 microM (2.0-fold), possibly pointing to an estrogen receptor-mediated regulation of this gene. Immunocytochemical staining revealed an induction of metallothionein proteins at 30 microM genistein, while their intracellular localization was unaffected. Metallothioneins were previously found to protect cells from hydrogen peroxide-induced DNA damage. Hence, our findings indicate that genistein protects prostate cells from oxidative stress-related DNA damage presumably by inducing the expression of antioxidative products, such as metallothioneins. Genistein, therefore, might counteract the age-related decline of important antioxidative defence systems which in turn maintain DNA integrity.     

Enhancement of paclitaxel activity against hormone-refractory prostate cancer cells in vitro and in vivo by quinacrine.

Cytoplasmic phospholipase A2 (PLA2) is known to be phosphorylated and activated by MAP kinase (Lin et al 1993, Cell 72: 269-278), an important downstream component of signal transduction, whereas paclitaxel has been shown to inhibit isoprenylation of ras proteins (Danesi et al 1995, Mol Pharmacol 47: 1106-1111). Given that quinacrine (Q), a PLA2 inhibitor, and paclitaxel (P) might act at different sites in the cell signalling pathway, our aim was to test whether they were synergistic in combination against prostate cancer cells. Cell viability of PC-3, PC-3M and DU145 cells in 96 - well plates was assessed 96 h after drugs were added concurrently. Using Chou analysis, we demonstrated synergy for the combination against all three cell lines. Further, synergy was present under both conservative (mutually non-exclusive) and non-conservative (mutually exclusive) models. Studies in the nude mouse xenograft model support the finding of synergy in vitro. In DU145-bearing mice, Q (50 mg kg(-1)) and P (0.5 mg kg(-1)) given daily for 12 consecutive days, either concurrently or sequentially, was more effective than either drug alone, at twice the dose intensity. In an enzyme-linked immunosorbent (ELISA) apoptosis assay, arachidonic acid was able to partially reverse Q- and P-induced apoptosis, suggesting PLA2 pathway involvement. Finally, the combination of lovastatin, another inhibitor of ras isoprenylation, and quinacrine had synergistic inhibitory effects on the growth of PC-3 cells in vitro, suggesting that the combination of these two classes of compounds might serve as an attractive therapeutic approach for prostate cancer.     

Enhanced paracrine FGF10 expression promotes formation of multifocal prostate adenocarcinoma and an increase in epithelial androgen receptor

Enhanced mesenchymal expression of FGF10 led to the formation of multifocal PIN or prostate cancer. Inhibition of epithelial FGFR1 signaling using DN FGFR1 led to reversal of the cancer phenotype. A subset of the FGF10-induced carcinoma was serially transplantable. Paracrine FGF10 led to an increase in epithelial androgen receptor and synergized with cell-autonomous activated AKT. Our observations indicate that stromal FGF10 expression may facilitate the multifocal histology observed in prostate adenocarcinoma and suggest the FGF10/FGFR1 axis as a potential therapeutic target in treating hormone-sensitive or refractory prostate cancer. We also show that transient exposure to a paracrine growth factor may be sufficient for the initiation of oncogenic transformation.     

LMO2蛋白在前列腺基质细胞中介导的IL-11、FGF-9旁分泌促进前列腺癌细胞增殖与侵袭

背景与目的：前列腺癌多发生于前列腺外周带,前列腺增生多发于前列腺移行带。前列腺疾病的带性差异机制可能与前列腺组织微环境有关。该研究的前期研究提示,不同区带来源的前列腺基质细胞对上皮细胞的作用存在明显差异,基因芯片筛查发现LMO2蛋白在前列腺外周带基质细胞高表达与前列腺癌发生、发展密切相关。该研究旨在分析前列腺基质细胞LMO2基因的表达对前列腺癌细胞系增殖、侵袭能力的影响及其机制。方法：分别应用慢病毒过表达载体和短发卡RNA(shRNA)建立过表达和低表达LMO2的前列基质细胞,利用实时荧光定量聚合酶链反应(real-time lfuorescent quantitative polymerase chain reaction,RTFQ-PCR)、蛋白[质]印迹法(Western blot)分别检测LMO2 mRNA和蛋白的表达;将不同处理的前列腺基质细胞分别同PC-3细胞共培养,利用CCK-8检测PC-3的增殖能力,利用基质胶侵袭实验检测PC-3的侵袭能力;利用生物素标记的人蛋白抗体芯片检测过表达LMO2的前列腺基质细胞条件培养基中蛋白因子表达变化。结果：成功建立过表达及低表达LMO2的前列腺基质细胞;CCK-8实验及基质胶实验提示,与过表达LMO2的前列腺WPMY-1基质细胞共培养后,PC-3细胞的增殖和侵袭能力增强;与低表达LMO2的CAFs细胞共培养后,PC-3细胞的增殖和侵袭能力降低;蛋白芯片检测发现过表达LMO2后,前列腺外周带基质细胞分泌白介素-11(interleukin-11, IL-11)和成纤维细胞生长因子-9(ifbroblast grouth factor-9,FGF-9)增多。结论：LMO2基因在前列腺外周基质细胞中的高表达可能与前列腺癌的发生、发展有关;过表达LMO2的前列腺基质细胞通过旁分泌IL-11、FGF-9等细胞因子促进前列腺癌细胞增殖与侵袭。     

人大肠腺瘤和腺癌之间相关差异蛋白的蛋白质组学研究

目的　应用蛋白质组学的方法,建立人大肠腺癌组织、大肠腺瘤组织、正常大肠黏膜组织的二维电泳图谱,筛选并鉴定三者之间的差异蛋白,发现人大肠癌的潜在生物学标志物。方法　收集同时患有大肠腺瘤的大肠腺癌患者１０例,术前及术后病理证实均为Ｄｕｋｅｓ’Ｂ期。取同一患者术后大肠癌组织、距大肠癌组织１５ｃｍ以上正常大肠黏膜组织以及肠镜下切除大肠腺瘤组织,提取不同组织总蛋白进行二维电泳,用ＩｍａｇｅＭａｓｔｅｒ２ＤＰｌａｔｉｎｕｍ５.０凝胶图像分析软件对双向电泳图依次进行凝胶点的检测、背景消减和编号。识别不同组织之间的差异蛋白点,对差异蛋白点用胶内酶解后行质谱分析和网上数据库鉴定。结果　大肠腺癌组织、大肠腺瘤组织和正常大肠黏膜组织之间存在９０个差异蛋白点。对这些差异点进行质谱分析,经数据库鉴定出７１个蛋白质。经分析,大肠腺瘤组织与正常大肠黏膜组织相比,１７个蛋白表达上调,９个蛋白表达下调;大肠腺癌组织与正常大肠黏膜组织比较,４７个蛋白表达上调,１２个蛋白表达下调;大肠腺癌组织与大肠腺瘤组织相比,３５个蛋白表达上调,８个蛋白表达下调。结论　大肠腺癌组织、大肠腺瘤组织和正常大肠黏膜组织之间存在差异蛋白表达,可能与大肠腺癌的发生发展有关;应用蛋白质组学方法筛选人大肠腺癌发生发展相关蛋白是可行的。     

Correlation between size and localization of stage-pT adenocarcinoma of the prostate

According to the data on resected material sampled from 58 cases of radical prostatectomy, a relationship between size of adenocarcinoma and prostate and localization of the main tumor node, on the one hand, and pathological stage (pT) of primary tumor was established. Incidence of pT3 was dependent on tumor volume when adenocarcinoma was in the periphery of the prostate which involved the following relationships between pT, on the one hand, and tumor size and site, on the other: the closer tumor to the gland center, the lower the value of pT. Conversely, peripheral zone size showed the least variation in elderly men. Risk of pT3 appeared to be associated with small size of the prostate. Our findings may be used for identification of tumor size and pathology detection by means of biopsy prior to surgery.     

Differences in leucocyte-endothelium interactions between normal and adenocarcinoma bearing tissues in response to radiation.

Previously, we demonstrated that the interaction between leucocytes and endothelial cells in tumour tissues is greatly diminished compared with normal tissues under several induced inflammatory conditions. Radiation has been reported to cause release of inflammatory mediators and to promote neutrophil adhesions to cultured endothelial monolayers. In this study, we tested the hypothesis that radiation would cause increased leucocyte rolling and adhesion in both tumour and normal tissues. We examined these two parameters in response to 6 Gy of gamma-radiation in mammary adenocarcinomas implanted into rat skinfold window chambers as well as normal (i.e. non-tumour-bearing) preparations. Leucocyte rolling and adhesion were measured in terms of flux of rolling leucocytes (F(rolling)) and density of adhering leucocytes (D(adhering)) in microvessels. F(rolling) and D(adhering) were measured in two groups of preparations: irradiated and control. In normal preparations, F(rolling) and D(adhering) were both increased significantly by radiation. In contrast, in adenocarcinoma-bearing preparations, F(rolling) and D(adhering) were either unchanged (in the tumour centre) or reduced (in tumour periphery and the normal tissue surrounding the tumour) by radiation. Radiation did not cause changes in haemodynamics in these preparations, thus the observed changes in leucocyte rolling and adhesion could not be accounted for by haemodynamic factors. These results indicate that: (1) in normal preparations, radiation could cause inflammation as manifested by increased leucocyte rolling and adhesion; and (2) in tumour-bearing preparations, radiation caused changes in the vascular surface properties such that they became less adhesive to leucocytes. Such differences in radiation response may have important implications for radiation therapy and provide new insights into the unique features of tumours.     

Rat prostate adenocarcinoma cells disseminate to bone and adhere preferentially to bone marrow-derived endothelial cells.

Approximately 70% of patients with prostatic cancer develop bone metastases. Metastatic prostate adenocarcinomas are associated with high mortality rates and represent a leading cause of cancer-related deaths among males. To study the host-tumor interactions underlying the predilection of prostate cancer cells for skeletal bone, an experimental model was developed using rat Dunning carcinoma Mat-LyLu cells. Inoculations of these cells into the left ventricle of the heart led to the development of spinal metastases in 100% of inoculated animals. A subline of Mat-LyLu (Mat-LyLu-B5) was subsequently selected through the sequential inoculation of bone marrow-derived carcinoma cells into the left ventricle and was found to have an increased metastatic potential compared to the parental line. The possible role of tumor cell adhesion to host cells in the process of bone marrow colonization was then investigated in vitro using the metastatic line and primary cultures of rat bone marrow-derived stromal cells. It was found that the adhesion of the metastatic Mat-LyLu cells to a bone marrow stromal cell culture highly enriched for endothelial cells was significantly higher than the adhesion to other bone-derived cells, including nonendothelial bone marrow stromal cells (3.5x) and osteoblasts (1.7x). It was also significantly higher than the adhesion to rat fibroblasts (7x) and to hepatic endothelial cells (7.5x). The results suggest that the adhesion of prostate carcinoma cells to the bone marrow endothelium may play a role in their metastasis to bone.     

Modelling the consequences of interactions between tumour cells.

Classical models of tumorigenesis assume that the mutations which cause tumours to grow act in a cell-autonomous fashion. This is not necessarily true. Sometimes tumour cells may adopt genetic strategies that boost their own replication and which also influence other cells in the tumour, whether directly or as a side-effect. Tumour growth as a whole might be enhanced or retarded. We have used mathematical models to study two non-autonomous strategies that tumour cells may use. First, we have considered the production by tumour cells of an angiogenesis growth factor that benefits both the cell from which it originates and neighbouring cells. Second, we have analysed a situation in which tumour cells produce autocrine-only or paracrine-only growth factors to prevent programmed cell death. In the angiogenesis model, stable genetic polymorphisms are likely to occur between cells producing and not producing the growth factor. In the programmed cell death model, cells with autocrine growth factor production can spread throughout the tumour. Production of paracrine-only growth factor is never selected because it is ''altruistic'' (that is of no benefit to the cell that makes the growth factor), despite being potentially beneficial to tumour growth as a whole. No polymorphisms can occur in the programmed cell death model. Production of angiogenesis and other growth factors in tumours may be under stable genetic, rather than epigenetic, control, with implications for therapies aimed at such targets. Many of the mutations observed in tumours may have non-autonomous effects.     

Chromosomal basis of adenocarcinoma of the prostate.

Prostate cancer is the most frequent malignancy and the second leading cause of cancer deaths among males in the Western world. The clinical course of the disease is highly complex, and genetic factors underlying tumorigenesis are poorly understood. The challenge that lies ahead is to identify the important gene(s) that causes adenocarcinoma of the prostate. Chromosomal findings by cytogenetic and molecular methods, including Southern blotting, microsatellite analysis, fluorescence in situ hybridization, and comparative genomic hybridization, revealed a high frequency of chromosomal aberrations of heterogeneous nature, including: -1, +1, -1q, +4, -6q, -7, +7, -8, -8p, -8q, +i(8q), -9, -9p, -10, +10, +11, -12, -13q, -16, -16q, +16, -17, +17, +17q, -18, +18, -18q, +19p, +20q, +X, -Xq, -Y, and +Y. Specific chromosomal regions of alterations were 1q24-25, 2cen-q31, 5cen-q23.3, 6q14-23.2, 7q22-q31, 8p12-21, 8p22, 8q24-qter, 10q22.1, 10q23-25, 11p11.2, 16q24, 17p13.1, 18q12.2, and Xq11-12. Recently, a predisposing gene for early onset has been localized on 1q42.2-43. The losses of heterozygosity at specific chromosomal loci from chromosomes 5q, 6q, 7q, 8p, 8q, 10q, 13q, 16q, 17p, 17q, and 18q are generally correlated with poor prognosis in advanced tumor stage. In addition, an abnormal function of known tumor suppressor genes from these regions have been observed in prostate cancer. Although, the amplification of the androgen receptor gene at Xq11-13 and HER-2/neu gene at 17q11.2-q12 are novel findings, no single gene has been implicated in harboring prostate cancer. Frequent inactivation of PTEN/MMAC1 tumor suppressor gene at 10q23, MXI-1 at 10q25, KAI-1 at 11p11.2, Rb at 13q14.2, and p53 at 17p13.1 and deregulation of c-myc oncogene at 8q24 have recently been the subject of intense scrutiny and debate.     

Positive interactions between human interferon and cepharanthin against human cancer cells in vitro and in vivo

A human tumor microcytotoxicity-viable cell-staining assay was used to test the antiproliferative effect of recombinant human interferon-beta or-gamma alone and in combination with bisbenzylisoquinoline alkaloid cepharanthin against four human tumor cell lines in vitro and in nude mice. Results obtained in the in vitro study indicate that combinations of interferon-beta/gamma with cepharanthin show synergistic and, occasionally, additive antiproliferative effects in a dose-dependent manner on tumor viable cell-staining assay. Interferon-gamma combined with cepharanthin suppressed the growth of all four human tumor cell lines (RPMI 4788, PC 10, HeLa, ZR-75-1), and this enhanced antiproliferative effect was not dependent on the interferon species involved, including interferon-beta and-gamma. In an experimental model of pulmonary metastasis, in which human colon tumor cells were inoculated i.v. into nude mice, interferon-gamma alone exerted significant inhibitory activity against pulmonary metastasis in a dose-dependent manner, and cepharanthin alone also significantly inhibited metastasis. Furthermore, a combination of interferon-gamma with cepharanthin resulted in a considerable suppression of pulmonary metastasis. These studies indicate that due to their therapeutic potential, combinations of recombinant human interferon-beta or-gamma with cepharanthin might be a promising therapy for pulmonary metastasis of human cancers.     

In vitro evaluation of schedule-dependent interactions between docetaxel and doxorubicin against human breast and ovarian cancer cells.

Docetaxel, a novel member of the taxoid family, has shown greater potency than paclitaxel in the treatment of advanced breast cancer and certain other solid tumors. The promising clinical activity of docetaxel has also promoted considerable interest in combining this drug with other antitumor agents. In this study, we assessed the cytotoxic interaction between docetaxel and doxorubicin administered at various schedules to human breast and ovarian cancer cells. Through a series of in vitro assays including DNA fragmentation analyses, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, and flow cytometric analyses, we found that the antagonistic interaction occurred when tumor cells were exposed to the two drugs simultaneously or exposed to doxorubicin before docetaxel. However, no antagonism was observed when docetaxel was added before doxorubicin. Further analyses demonstrated that doxorubicin could interfere with the cytotoxic effect of docetaxel on both mitotic arrest and apoptotic cell death. In addition, biochemical examinations revealed that docetaxel could induce phosphorylation of both bcl-2 and c-raf-1, but these changes were inhibited when tumor cells were pretreated or simultaneously treated with doxorubicin. These results indicate that the interaction between docetaxel and doxorubicin is highly schedule dependent. Exposure of tumor cells to doxorubicin before docetaxel could result in pronounced antagonism. The optimal schedule for this combination might be sequential exposure to docetaxel followed by doxorubicin.