Estrone-induced,prolactin-secreting and dopamine-sensitive rat pituitary tumor

Prolactin (PRL)-secreting rat pituitary tumors were induced in female Fisher 344/Lis rats by s.c. implants of estrone (E₁) pellets. Tumor growth was relatively fast and reached about 100 mg within 2 months. Ovariectomy at the time of E₁ implants seemed to accelerate the growth of the tumors. Tumor cells in primary culture produced mainly PRL, while growth hormone (GH) release was about 2% of PRL production and the release of some other pituitary homrones did not exceed 1% of PRL values. Tumor cells were found to have high-affinity dopamine (DA) receptors. The addition of DA in vitro at 10⁻¹⁰M concentration stimulated PRL release, while at 10⁻⁶M concentration it inhibited the release of the hormone by more than 50% of control values. Histological, immunohistochemical and electron microscopical studies demonstrated the tumor to be composed mainly of maximally stimulated mammotrophs.     

Effects of megestrol acetate on growth and secretion of a pituitary tumor

The effect of the administration of the6-methylated progestagen megestrol acetate on the growth of the estrogen-induced transplantable PRL/ACTH-secreting rat pituitary tumor7315a was investigated. A significant inhibition of tumor growth was observed only during the last week of a four week period of drug administration (6 mg/kg). Administration of megestrol acetate suppressed the total content and the ability to release PRL, ACTH and LH of the pituitary gland of tumor bearing rats. Further, a significant suppression of the anterior pituitary, ovarian and uterine weights was observed in the megestrol acetate treated animals. Megestrol acetate did not exert a direct effect on PRL, ACTH and LH secretion by normal rat pituitary glands incubated in vitro.We conclude that megestrol acetate exerts in the model used a suppressive effect on PRL, ACTH and LH release and led to a diminution of the pituitary content of these hormones, while it has also anti-estrogenic and anti-androgenic properties. The effects of the drug help further explain its beneficial effects in metastatic breast, endometrial, renal and prostatic cancer in man.     

Prolactin release-inhibitory effects of progesterone, megestrol acetate, and mifepristone (RU 38486) by cultured rat pituitary tumor cells

The prolactin (PRL) release-inhibitory effects of progesterone, dexamethasone, megestrol acetate, and mifepristone (RU 38486) were studied in cultured pituitary tumor cells prepared from the 7315a and 7315b tumor. Both tumors contain similar numbers of estrogen and progesterone receptors, while only the 7315a tumor also has glucocorticoid receptors. PRL release by the 7315a tumor was stimulated by low concentrations of dexamethasone (10(-10)-10(-9) M) and was inhibited in a dose-dependent manner by higher concentrations (-86% by 10(-7) M). In contrast only 10(-6) and 10(-5) M dexamethasone inhibited PRL release by the 7315b cells by 14 and 24%, respectively. Progesterone caused a dose-dependent inhibition of PRL release, which was similar in the 7315a and b tumor cells. Progesterone (10(-9) M) inhibited PRL release by 62% and this inhibition was completely prevented by 100 nM estradiol, which was stimulatory by itself (+48%). Mifepristone inhibited PRL release by both tumors in a dose-dependent manner, but more powerfully in the 7315a tumor; 10(-6) M concentrations of the compound inhibited PRL release by 52% in the 7315a and by 26% in the 7315b tumor cells. Megestrol acetate inhibited PRL release in both tumors in a dose-dependent manner, but more powerfully in the 7315b tumor; a 10(-8) M concentration of the compound inhibited PRL release by 54% in the 7315b tumor and by 14% in the 7315a tumor. In the 7315a tumor 10(-9) M megestrol acetate even stimulated PRL release, suggesting a dexamethasone-like glucocorticoid effect of the drug on this tumor. Thereafter the interaction of mifepristone and megestrol acetate on PRL release was investigated. In the 7315a tumor cells different combinations of both drugs neutralized each other's inhibitory effects on PRL release, while both drugs had additional inhibitory effects on PRL release by 7315b tumor cells. Changes in PRL release by the cultured pituitary tumor cells were in all instances closely correlated with changes in the PRL content, the protein content, and the DNA content of the tumor cells. This suggests that the inhibitory effect of the compounds studied on PRL release is paralleled by an inhibitory effect on the number of pituitary tumor cells. These studies show the importance of the presence of glucocorticoid receptors in the effectiveness and mechanism of action of the antitumor effects of megestrol acetate and mifepristone.(ABSTRACT TRUNCATED AT 400 WORDS)     

Purification and identification of a polysaccharide from medicinal mushroom Amauroderma rude with immunomodulatory activity and inhibitory effect on tumor growth

Medicinal mushrooms in recent years have been the subject of many experiments searching for anticancer properties. We previously screened thirteen mushrooms for their potential in inhibiting tumor growth, and found that the water extract of Amauroderma rude exerted the highest activity. Previous studies have shown that the polysaccharides contained in the water extract were responsible for the anticancer properties. This study was designed to explore the potential effects of the polysaccharides on immune regulation and tumor growth. Using the crude Amauroderma rude extract, in vitro experiments showed that the capacities of spleen lymphocytes, macrophages, and natural killer cells were all increased. In vivo experiments showed that the extract increased macrophage metabolism, lymphocyte proliferation, and antibody production. In addition, the partially purified product stimulated the secretion of cytokines in vitro, and in vivo. Overall, the extract decreased tumor growth rates. Lastly, the active compound was purified and identified as polysaccharide F212. Most importantly, the purified polysaccharide had the highest activity in increasing lymphocyte proliferation. In summary, this molecule may serve as a lead compound for drug development.     

Antiangiogenic liposomal gene therapy with 16K human prolactin efficiently reduces tumor growth

Human 16K PRL (16K hPRL) is a potent inhibitor of angiogenesis both in vitro and in vivo. It has been shown to prevent tumor growth in three xenograft mouse models. Here we have used a gene transfer method based on cationic liposomes to produce 16K hPRL and demonstrate that 16K hPRL inhibits tumor growth in a subcutaneous B16F10 mouse melanoma model. Computer-assisted image analysis shows that 16K hPRL treatment results in the reduction of tumor vessel length and width, leading to a 57% reduction in average vessel size. We thus show, for the first time, that administration of the 16K hPRL gene complexed to cationic liposomes is effective to maintain antiangiogenic activities of 16K hPRL level.     

PTPRG suppresses tumor growth and invasion via inhibition of Akt signaling in nasopharyngeal carcinoma

Protein Tyrosine Phosphatase, Receptor Type G (PTPRG) was identified as a candidate tumor suppressor gene in nasopharyngeal carcinoma (NPC). PTPRG induces significant in vivo tumor suppression in NPC. We identified EGFR as a PTPRG potential interacting partner and examined this interaction. Dephosphorylation of EGFR at EGFR-Y1068 and -Y1086 sites inactivated the PI3K/Akt signaling cascade and subsequent down-regulation of downstream pro-angiogenic and -invasive proteins (VEGF, IL6, and IL8) and suppressed tumor cell proliferation, angiogenesis, and invasion. The effect of Akt inhibition in NPC cells was further validated by Akt knockdown experiments in the PTPRG-down-regulated NPC cell lines. Our results suggested that inhibition of Akt in NPC cells induces tumor suppression at both the in vitro and in vivo levels, and also importantly, in vivo metastasis. In conclusion, we confirmed the vital role of PTPRG in inhibiting Akt signaling with the resultant suppression of in vivo tumorigenesis and metastasis.     

BmKCT toxin inhibits glioma proliferation and tumor metastasis

Malignant gliomas are the most common primary brain tumors associated with significant morbidity and mortality. How to target the tumor in situ, and inhibit tumor cell proliferation and invasion is the key for therapy. Gliomas express a glioma-specific chloride ion channel that is sensitive to toxins including BmKCT. In the current study, the inhibitory effect of BmKCT on glioma growth was observed in vivo using the glioma/SD rat model. Furthermore, BmKCT prevented the metastasis of glioma cells in vivo. Moreover, biodistribution experiments with ^l3lI-labeled or Cy5.5-conjugated BmKCT revealed that BmKCT selectively targeted the glioma in situ. Our data suggest that BmKCT could be exploited as a potential therapeutic for glioma diagnosis and therapy.     

Silibinin-mediated metabolic reprogramming attenuates pancreatic cancer-induced cachexia and tumor growth

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related deaths in the US. Cancer-associated cachexia is present in up to 80% of PDAC patients and is associated with aggressive disease and poor prognosis. In the present studies we evaluated an anti-cancer natural product silibinin for its effectiveness in targeting pancreatic cancer aggressiveness and the cachectic properties of pancreatic cancer cells and tumors. Our results demonstrate that silibinin inhibits pancreatic cancer cell growth in a dose-dependent manner and reduces glycolytic activity of cancer cells. Our LC-MS/MS based metabolomics data demonstrates that silibinin treatment induces global metabolic reprogramming in pancreatic cancer cells. Silibinin treatment diminishes c-MYC expression, a key regulator of cancer metabolism. Furthermore, we observed reduced STAT3 signaling in silibinin-treated cancer cells. Overexpression of constitutively active STAT3 was sufficient to substantially revert the silibinin-induced downregulation of c-MYC and the metabolic phenotype. Our in vivo investigations demonstrate that silibinin reduces tumor growth and proliferation in an orthotopic mouse model of pancreatic cancer and prevents the loss of body weight and muscle. It also improves physical activity including grip strength and latency to fall in tumor-bearing mice. In conclusion, silibinin-induced metabolic reprogramming diminishes cell growth and cachectic properties of pancreatic cancer cells and animal models.     

Efficacy of local delivery of ardipusilloside I using biodegradable implants against cerebral tumor growth

Ardipusilloside I (ADS-I) is a natural compound that can be isolated from the Chinese medicinal herb Ardisiapusilla A.DC, and has been reported to inhibit the growth of glioblastoma cells in cultures. This study was designed to test its efficacy by the delivery using biodegradable implants against glioblastoma in vivo. ADS-I was incorporated into polymer microspheres, which were prepared by a mixture of poly (D, L-lactic acid) and poly (D, L-lactic-co-glycolic acid) polymers and then fabricated into wafers. The anti-glioma activities of ADS-I-loaded wafers were examined by methylthiazol tetrazolium (MTT) assay in cultured rat C6 glioma cells, and by magnetic resonance imaging (MRI) and survival monitoring in C6 glioma-bearing rats. Here, we showed that ADS-I-loaded wafers sustained ADS-I release in vitro for 36 days in Higuchi model of kinetics, and had the same cytotoxic activity as ADS-I in the solution against the growth of C6 glioma cells in cultures. In C6 glioma-bearing rats, ADS-I wafer implants inhibited tumor growth in a dose-dependent matter, and were more effective than the same dosage of ADS-I in the solution. The tumor suppression efficacies of ADS-I wafer implants were positively correlated with an increase in tumor cell apoptosis and prolonged animal survival, and were associated with a decrease in vascular endothelial growth factor, C-reactive protein, tumor necrosis factor-α and interleukin-6, and an increase in interleukin-2 expression. In conclusion, this study demonstrates significant efficacy of local delivery of ADS-I using polymer implants against glioma tumor growth in vivo, suggesting the potential of ADS-I-loaded wafers for glioma treatment.     

Curcumin inhibits angiogenesis and improves defective hematopoiesis induced by tumor-derived VEGF in tumor model through modulating VEGF-VEGFR2 signaling pathway

Curcumin, a natural polyphenol compound from the perennial herb Curcuma longa, has been proved to be beneficial for tumor-bearing animals through inhibiting tumor neovasculature formation, but the underlying mechanisms are unclear. Here, we aim to test whether curcumin affects VEGF-VEGFR2 signaling pathway and attenuates defective hematopoiesis induced by VEGF in tumor model. We demonstrated that curcumin inhibited proliferation, migration of HUVEC under VEGF stimulation and caused HUVEC apoptosis, and blocked VEGFR2 activation and its downstream signaling pathways in vitro. Furthermore, in VEGF over-expressing tumor model, curcumin significantly inhibited the tumor growth accelerated by VEGF in a dose-dependent manner and improved anemia and extramedullary hematopoiesis in livers and spleens of tumor-bearing mice induced by tumor-derived VEGF. Immunohistochemical analysis showed that curcumin normalized vasculature structures of livers and reduced tumor microvessel density. ELISA revealed that curcumin suppressed VEGF secretion from tumor cells both in vitro and in vivo. Survival analysis showed that curcumin significantly improved survival ability of VEGF tumor-bearing mice. Taken together, these findings establish curcumin as a modulator of VEGF and VEGF-VEGFR2 signaling pathway, with potential implication for improving the quality of life of cancer patients.     

CUEDC2 down-regulation is associated with tumor growth and poor prognosis in lung adenocarcinoma

CUE domain-containing 2 (CUEDC2) is a multi-functional protein, which regulates cell cycle, growth factor signaling and inflammation. We found that CUEDC2 was low in lung adenocarcinoma cell lines and lung adenocarcinoma tissues at both mRNA and protein levels. Low levels of CUEDC2 were correlated with a shorter survival time in patients with lung adenocarcinoma (p = 0.004). CUEDC2 expression was correlated with tumor T classification (P = 0.001) at clinical stage (P = 0.001) and tumor size (P = 0.033). Multivariate analysis suggested that CUEDC2 expression is an independent prognostic indicator for patients with lung adenocarcinoma. Ectopic expression of CUEDC2 decreased cell proliferation in vitro and inhibited tumor growth in nude mice in vivo. Knockdown of endogenous CUEDC2 by short hairpin RNAs (shRNAs) increased tumor growth. Inhibition of proliferation by CUEDC2 was associated with inactivation of the PI3K/Akt pathway, induction of p21 and down-regulation of cyclin D1. Our results suggest that decreased expression of CUEDC2 contributes to tumor growth in lung adenocarcinoma, leading to a poor clinical outcome.     

Vaccination with xenogeneic tumor endothelial proteins isolated in situ inhibits tumor angiogenesis and spontaneous metastasis

Angiogenesis is critical for tumor growth and metastasis. Tumor tissues induce the expression of angiogenesis‐associated proteins on endothelial surface that can be targeted for tumor immunotherapy. In our study, the rat tumor endothelial proteins (EP) were isolated in situ via biotinylation of tumor vascular endothelial luminal surface followed by streptavidin affinity chromatography. The isolated tumor EP contained numerous up‐regulated angiogenesis‐associated endothelial proteins. The administration of these tumor EP as a vaccine to mice reduced the microvessel density in subcutaneous primary LLC tumors, delayed spontaneous LLC tumor metastasis and prolonged post‐surgery life span. T lymphocytes from tumor EP‐vaccinated mice lysed human umbilical vascular endothelial cells, but not tumor cells in vitro, in a dose‐dependent manner. Furthermore, adoptive transfer of antitumor EP antibodies in vivo targeted to tumor endothelium and inhibited spontaneous LLC tumor metastasis. This study provides a successful preclinical exploration of the active immunotherapy for tumor by targeting tumor angiogenesis. © 2009 UICC     

Inhibition of neovascularization and tumor growth, and facilitation of wound repair, by halofuginone, an inhibitor of collagen type I synthesis

Halofuginone, an inhibitor of collagen α1(I) gene expression was used for the treatment of subcutaneously implanted C6 glioma tumors. Halofuginone had no effect on the growth of C6 glioma spheroids in vitro, and these spheroids showed no collagen α1(I) expression and no collagen synthesis. However, a significant attenuation of tumor growth was observed in vivo, for spheroids implanted in CD-1 nude mice which were treated by oral or intraperitoneal (4 µg every 48 hours) administration of halofuginone. In these mice, treatment was associated with a dose-dependent reduction in collagen α1(I) expression and dose- and time-dependent inhibition of angiogenesis, as measured by MRI. Moreover, halofuginone treatment was associated with improved re-epithelialization of the chronic wounds that are associated with this experimental model. Oral administration of halofuginone was effective also in intervention in tumor growth, and here, too, the treatment was associated with reduced angiogenic activity and vessel regression. These results demonstrate the important role of collagen type I in tumor angiogenesis and tumor growth and implicate its role in chronic wounds. Inhibition of the expression of collagen type I provides an attractive new target for cancer therapy.     

Tanshinone IIA inhibits cell growth by suppressing SIX1-induced aerobic glycolysis in non-small cell lung cancer cells

Aerobic glycolysis plays a key role in cancer cell metabolism and contributes to tumorigenesis, including that of non-small cell lung cancer (NSCLC). Tanshinone IIA (Tan IIA), an active compound of Salvia miltiorrhiza, exhibits antitumor properties. Multiple mechanisms are involved in the antitumor action of Tan IIA in lung cancer, such as inhibiting cell growth, promoting cell apoptosis and influencing cellular metabolism. However, the effects of Tan IIA on NSCLC cells and its mechanisms of action remain unclear. The present study shows Tan IIA dose-dependently attenuated the growth of NSCLC cells and in vitro in a dose-dependent manner. Moreover, Tan IIA markedly decreased the ATP level, glucose uptake and lactate production in the NSCLC cells in vitro. Tan IIA also inhibited tumor growth in a xenograft model in vivo. Mechanically, Tan IIA treatment decreased sine oculis homeobox homolog 1 (SIX1) mRNA and protein levels, thus leading to the downregulation of pyruvate kinase isozyme M2, hexokinase 2 and lactate dehydrogenase A (LDHA) expression in A549 cells. SIX1 knockdown with small interfering-RNA inhibited glycolysis in NSCLC cells, suggesting that SIX1 plays a role in the antitumor effect of Tan IIA on NSCLC cells. More importantly, it was demonstrated that SIX1 expression was stimulated in patients with NSCLC and was positively correlated with the LDH serum level. Finally, SIX1 low expression levels predicted the poor prognosis of patients with NSCLC. In conclusion, the present study showed that Tan IIA functioned as an anti-glycolysis agent in NSCLC cells by downregulating SIX1 expression and inhibiting cell proliferation.     

Spleen cells of whole body X-irradiated W/Fu rats enhance tumor growth in vivo and non-specific cytotoxicity in vitro

This study was designed to investigate the influence of spleen cells of normal Wistar/Furth (W/Fu) rats obtained after whole body X-irradiation (WBI) upon mammary carcinoma growth in vivo, and cell mediated cytotoxicity against several target cells in vitro. The ME/H mammary carcinoma employed here originally arose spontaneously in a W/Fu rat, metastasizing to the retroperitoneal lymph node and lungs. It was found that surviving non-adherent spleen cells taken two days after 500R WBI cause enhanced tumor growth and metastases development in a Winn assay compared with nonadherent spleen cells from unirradiated controls. These cells were also enriched in granulocytes compared with controls. While the level of nonspecific cell mediated cytotoxicity was variable, it increased significantly following WBI of the spleen cell donor. Our results indicate that there are apparently two opposing effects shown by non-adherent spleen cells surviving WBI of normal W/Fu rats: enhancement of in vivo tumor growth, and enhancement of in vitro cell mediated cytotoxicity. A possible mechanism to explain these contrasting results is suggested.     

Determinates of tumor response to radiation: Tumor cells,tumor stroma and permanent local control

Background and purposeThe causes of tumor response variation to radiation remain obscure, thus hampering the development of predictive assays and strategies to decrease resistance. The present study evaluates the impact of host tumor stromal elements and the in vivo environment on tumor cell kill, and relationship between tumor cell radiosensitivity and the tumor control dose.Material and methodsFive endpoints were evaluated and compared in a radiosensitive DNA double-strand break repair-defective (DNA-PKcs^−/−) tumor line, and its DNA-PKcs repair competent transfected counterpart. In vitro colony formation assays were performed on in vitro cultured cells, on cells obtained directly from tumors, and on cells irradiated in situ. Permanent local control was assessed by the TCD₅₀ assay. Vascular effects were evaluated by functional vascular density assays.ResultsThe fraction of repair competent and repair deficient tumor cells surviving radiation did not substantially differ whether irradiated in vitro, i.e., in the absence of host stromal elements and factors, from the fraction of cells killed following in vivo irradiation. Additionally, the altered tumor cell sensitivity resulted in a proportional change in the dose required to achieve permanent local control. The estimated number of tumor cells per tumor, their cloning efficiency and radiosensitivity, all assessed by in vitro assays, were used to predict successfully, the measured tumor control doses.ConclusionThe number of clonogens per tumor and their radiosensitivity govern the permanent local control dose.