Effect of alcohol ingestion on carcinogenesis by synthetic estrogen and progestin in the rat liver

Novel Methionine Aminopeptidase 2 Inhibitor M8891 Synergizes with VEGF Receptor Inhibitors to Inhibit Tumor Growth of Renal Cell Carcinoma Models

N-terminal processing by methionine aminopeptidases (MetAP) is a crucial step in the maturation of proteins during protein biosynthesis. Small-molecule inhibitors of MetAP2 have antiangiogenic and antitumoral activity. Herein, we characterize the structurally novel MetAP2 inhibitor M8891. M8891 is a potent, selective, reversible small-molecule inhibitor blocking the growth of human endothelial cells and differentially inhibiting cancer cell growth. A CRISPR genome-wide screen identified the tumor suppressor p53 and MetAP1/MetAP2 as determinants of resistance and sensitivity to pharmacologic MetAP2 inhibition. A newly identified substrate of MetAP2, translation elongation factor 1-alpha-1 (EF1a-1), served as a pharmacodynamic biomarker to follow target inhibition in cell and mouse studies. Robust angiogenesis and tumor growth inhibition was observed with M8891 monotherapy. In combination with VEGF receptor inhibitors, tumor stasis and regression occurred in patient-derived xenograft renal cell carcinoma models, particularly those that were p53 wild-type, had Von Hippel-Landau gene (VHL) loss-of-function mutations, and a mid/high MetAP1/2 expression score.

Breast cancer, alcohol, and phosphate toxicity

Alcohol consumption is associated with an increased risk of breast cancer, even at low alcohol intake levels, but public awareness of the breast cancer risk associated with alcohol intake is low. Furthermore, the causative mechanisms underlying alcohol's association with breast cancer are unknown. The present theoretical paper uses a modified grounded theory method to review the research literature and propose that alcohol's association with breast cancer is mediated by phosphate toxicity, the accumulation of excess inorganic phosphate in body tissue. Serum levels of inorganic phosphate are regulated through a network of hormones released from the bone, kidneys, parathyroid glands, and intestines. Alcohol burdens renal function, which may disturb the regulation of inorganic phosphate, impair phosphate excretion, and increase phosphate toxicity. In addition to causing cellular dehydration, alcohol is an etiologic factor in nontraumatic rhabdomyolysis, which ruptures cell membranes and releases inorganic phosphate into the serum, leading to hyperphosphatemia. Phosphate toxicity is also associated with tumorigenesis, as high levels of inorganic phosphate within the tumor microenvironment activate cell signaling pathways and promote cancer cell growth. Furthermore, phosphate toxicity potentially links cancer and kidney disease in onco-nephrology. Insights into the mediating role of phosphate toxicity may lead to future research and interventions that raise public health awareness of breast cancer risk and alcohol consumption.

Connexin 32 dysfunction promotes ethanol-related hepatocarcinogenesis via activation of Dusp1-Erk axis

There is abundant epidemiological evidence that heavy alcohol intake contributes to hepatocellular carcinoma (HCC) development. Previous reports indicated that connexin 32 (Cx32), which is a major hepatocyte gap junction protein, is down-regulated in chronic liver disease and has a protective role in hepatocarcinogenesis. However, functions of Cx32 in alcohol-related hepatocarcinogenesis have not been clarified. To evaluate them, 9-week-old Cx32 dominant negative transgenic (Tg) rats and their wild-type (Wt) littermates were given 1 % or 5 % ethanol (EtOH) or water ad libitum, for 16 weeks after an intraperitoneal injection of diethylnitrosamine (200 mg/kg). EtOH significantly increased the incidence and multiplicity of HCC and total tumors in a dose-dependent manner in Tg rats, but not in Wt rats. Although the number and area of glutathione S-transferase placental form (GST-P) positive foci were not significantly different between the groups, EtOH increased the Ki-67 labeling indices in GST-P positive foci only in Tg rats. EtOH up-regulated phosphorylated Erk1/2 with decrease of the Erk1/2 inhibitor, dual specificity protein phosphatase 1 (Dusp1) in whole livers of Tg and Wt rats. Immunofluorescence staining and quantitative RT-PCR revealed that EtOH significantly increased nucleolar localization of phosphorylated Erk1/2 and contrastingly reduced Dusp1 protein and mRNA expression in GST-P positive foci and HCC of Tg rats as compared to those of Wt rats. These findings suggest that Cx32 dysfunction like in chronic liver disease promoted EtOH-associated hepatocarcinogenesis through dysregulation of Erk-Dusp1 signaling.

Role of sex steroid receptors in pathobiology of hepatocellular carcinoma

The striking gender disparity observed in the incidence of hepatocellular carcinoma (HCC) suggests an important role of sex hormones in HCC pathogenesis. Though the studies began as early as in 1980s, the precise role of sex hormones and the significance of their receptors in HCC still remain poorly understood and perhaps contribute to current controversies about the potential use of hormonal therapy in HCC. A comprehensive review of the existing literature revealed several shortcomings associated with the studies on estrogen receptor (ER) and androgen receptor (AR) in normal liver and HCC. These shortcomings include the use of less sensitive receptor ligand binding assays and immunohistochemistry studies for ERα alone until 1996 when ERβ isoform was identified. The animal models of HCC utilized for studies were primarily based on chemical-induced hepatocarcinogenesis with less similarity to virus-induced HCC pathogenesis. However, recent in vitro studies in hepatoma cells provide newer insights for hormonal regulation of key cellular processes including interaction of ER and AR with viral proteins. In light of the above facts, there is an urgent need for a detailed investigation of sex hormones and their receptors in normal liver and HCC. In this review, we systematically present the information currently available on androgens, estrogens and their receptors in normal liver and HCC obtained from in vitro, in vivo experimental models and clinical studies. This information will direct future basic and clinical research to bridge the gap in knowledge to explore the therapeutic potential of hormonal therapy in HCC.

Role of estrogen in alcohol promotion of breast cancer and prolactinomas

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chair was Dipak K. Sarkar. The presentations were (1) Dual role of estrogen as hormone and carcinogen in mammary carcinogenesis, by Joachim G. Liehr; (2) Alcohol and breast cancer: Studies using animals, by Keith W. Singletary; and (3) Evaluation of the role of estrogen in mediation of ethanol effect on prolactinoma: Studies using animals, by Dipak K. Sarkar.

Role of estrogen in alcohol promotion of breast cancer and prolactinomas

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chair was Dipak K. Sarkar. The presentations were (1) Dual role of estrogen as hormone and carcinogen in mammary carcinogenesis, by Joachim G. Liehr; (2) Alcohol and breast cancer: Studies using animals, by Keith W. Singletary; and (3) Evaluation of the role of estrogen in mediation of ethanol effect on prolactinoma: Studies using animals, by Dipak K. Sarkar.

Effect of ethanol on proliferation and estrogen receptor-alpha expression in human breast cancer cells

There is substantial epidemiological evidence suggesting that alcohol consumption is associated with increased risk for breast cancer. However, possible biological mechanisms have not been clearly established. In the present studies, a direct effect of ethanol on the proliferation and intracellular content of cyclic AMP (cAMP) in two estrogen receptor-positive (ER+) and two estrogen receptor-negative (ER-) human breast cancer cell lines was examined. Treatment of ER+ human breast cancer cells (MCF-7 and ZR75.1) with ethanol at concentrations between 10 and 100 mM was associated with increased cell numbers compared to controls. The ERalpha content and the amount of intracellular cAMP also increased in ER+ cells exposed to ethanol, compared to controls. On the other hand, ethanol treatment did not increase cell proliferation or cAMP levels in the ER- (BT-20 and MDA-MB-231) human breast cancer cells. Therefore, ethanol added at physiologically relevant concentrations to ER+ human breast cancer cell cultures can enhance cell proliferation and increase the content of ERalpha.

Estrogen induces cytokeratin aggregation in primary cultures of Armenian hamster hepatocytes

The effect of estrogen administration to cultured Armenian hamster was studied. Isolated Armenian hamster hepatocytes were cultured in RPMI medium supplemented with beta-estradiol (E2). Beta-estradiol treatment for 24-48 hr induced cytoplasmic inclusion bodies which by immunocytochemistry were positive for cytokeratin (CK) 8, CK 18, and ubiquitin but negative for CK 7 and CK 19. These inclusion bodies appeared as filamentous tangles or amorphous aggregates when observed by electron microscopy. F-actin, tubulin, and desmosomes were not influenced by the presence of the inclusion bodies. Addition of ethanol to culture medium increased the incidence of the inclusion formation. In combination with 0.5% ethanol 1 microM of E2 induced five to six times more inclusion bodies, while the number of inclusion bodies decreased when epidermal growth factor (EGF) was added to the medium in combination with E2. This reduction effect was nullified by treatment with anti-EGF receptor antibody. These findings suggest that E2 treatment to Armenian hamster hepatocytes in vitro induces Mallory body-like inclusions whose incidence can be influenced by addition of ethanol or EGF to the culture medium.

32P-postlabeling analysis of DNA adducts in rats during estrogen-induced hepatocarcinogenesis and effect of tamoxifen on DNA adduct level

DNA adduct formation in the liver, pancreas, kidneys and uterus in ethynylestradiol (EE)-induced carcinogenesis and the effect of tamoxifen (TAM) on DNA adduct formation were evaluated in female Wistar JCL rats using the 32P-postlabeling method. Hyperplastic nodules were noted in the liver of all rats 4 months after the first oral administration of 0.075 mg of EE, and hepatocellular carcinoma was detected in 8.1% of rats treated with EE for 12 months. DNA adducts increased in the liver for 4 months, reaching a level of 7.3 adducts/10(7) nucleotides and decreasing thereafter. Formation of DNA adducts was also noted in the pancreas and kidney, but the adduct levels were lower than those in the liver. TAM inhibited estrogen receptors (ER) in liver tissues and completely suppressed the development of hyperplastic nodules or hepatocellular carcinoma but did not affect DNA adduct formation in the liver. In this model, therefore, EE is considered to cause mutations of hepatocytes due to DNA adduct formation without mediation by ER and to induce initiated cells to develop into hepatocellular carcinoma in the presence of ER-mediated hormonal activities.