17β-Estradiol inhibits testosterone-induced cell proliferation in HepG2 by modulating the relative ratios of 3 estrogen receptor isoforms to the androgen receptor

Pharmacologically inducing anoikis offers novel therapeutic opportunities in hepatocellular carcinoma

Tumor metastasis occurs in hepatocellular carcinoma (HCC), leading to tumor progression and therapeutic failure. Anoikis is a matrix detachment-induced apoptosis, also known as detachment-induced cell death, and mechanistically prevents tumor cells from escaping their native extracellular matrix to metastasize to new organs. Deciphering the regulators and mechanisms of anoikis in cancer metastasis is urgently needed to treat HCC. Several natural and synthetic products induce anoikis in HCC cells and in vivo models. Here, we first briefly summarize the current understanding of the molecular mechanisms of anoikis regulation and relevant regulators involved in HCC metastasis. Then we discuss the therapeutic potential of pharmacological induction of anoikis as a potential treatment against HCC. Finally, we discuss the key limitations of this therapeutic paradigm and propose possible strategies to overcome them. Cumulatively this review suggests that the pharmacological induction of anoikis can be used a promising therapeutic modality against HCC.

The role of NLRP3 inflammasome in hepatocellular carcinoma

Inflammasomes play an important role in innate immunity. As a signal platform, they deal with the excessive pathogenic products and cellular products related to stress and injury. So far, the best studied and most characteristic inflammasome is the NLR-family pyrin domain-containing protein 3(NLRP3) inflammasome, which is composed of NLRP3, apoptosis associated speck like protein (ASC) and pro-caspase-1. The formation of NLRP3 inflammasome complexes results in the activation of caspase-1, the maturation of interleukin (IL)-1β and IL-18, and pyroptosis. Many studies have demonstrated that NLRP3 inflammasome not only participates in tumorigenesis, but also plays a protective role in some cancers. Hepatocellular carcinoma (HCC) is a major cause of cancer-related mortality. Currently, due to the lack of effective treatment methods for HCC, the therapeutic effect of HCC has not been ideal. Therefore, it is particularly urgent to explore the pathogenesis of HCC and find its effective treatment methods. The increasing evidences indicate that NLRP3 inflammasome plays a vital role in HCC, however, the related mechanisms are not fully understood. Hence, we focused on the recent progress about the role of NLRP3 inflammasome in HCC, and analyzed the relevant mechanisms in detail to provide reference for the future in-depth researches.

Naringenin and Quercetin Exert Contradictory Cytoprotective and Cytotoxic Effects on Tamoxifen-Induced Apoptosis in HepG2 Cells

Tamoxifen is commonly used to treat estrogen receptor-positive breast cancer and hepatocellular carcinoma. Phytoconstituents are considered candidates for chemopreventive drugs in cancer treatment. However, it remains unknown what would happen if tamoxifen and phytoconstituents were administrated simultaneously. We aimed to observe the synergistic antitumor effects of tamoxifen and naringenin/quercetin on human hepatic carcinoma and to explore the potential underlying molecular mechanisms. The HepG2 cell line was used as an in vitro model. Cell proliferation, invasion, migration, cycle progression and apoptosis were investigated along with reactive oxygen species (ROS) production and mitochondrial membrane potential (ΔΨm) repression. The signaling pathways involved were identified using real-time quantitative polymerase chain reaction analysis. As the results show, tamoxifen in combination with higher concentrations of naringenin or quercetin significantly inhibited cell growth compared to either agent alone. These antiproliferative effects were accompanied by the inhibition of cell migration and invasion but the stimulation of cell apoptosis and loss of ΔΨm, which depended on the ROS-regulated p53 signaling cascades. Conversely, lower concentrations of naringenin and quercetin inhibited the tamoxifen-induced cell antiproliferative effects by regulating cell migration, invasion, cycle and apoptosis. Taken together, our findings revealed that phytoconstituents exerted contradictory cytoprotective and cytotoxic effects induced by tamoxifen in human hepatic cancer.

Investigation of Radiotracer Metabolic Stability In Vitro with CYP-Overexpressing Hepatoma Cell Lines

The characterization of novel radiotracers toward their metabolic stability is an essential part of their development. While in vitro methods such as liver microsome assays or ex vivo blood or tissue samples provide information on overall stability, little or no information is obtained on cytochrome P450 (CYP) enzyme and isoform-specific contribution to the metabolic fate of individual radiotracers. Herein, we investigated recently established CYP-overexpressing hepatoblastoma cell lines (HepG2) for their suitability to study the metabolic stability of radiotracers in general and to gain insight into CYP isoform specificity. Wildtype HepG2 and CYP1A2-, CYP2C19-, and CYP3A4-overexpressing HepG2 cells were incubated with radiotracers, and metabolic turnover was analyzed. The optimized protocol, covering cell seeding in 96-well plates and analysis of supernatant by radio thin-layer-chromatography for higher throughput, was transferred to the evaluation of three ¹⁸F-labeled celecoxib-derived cyclooxygenase-2 inhibitors (coxibs). These investigations revealed time-dependent degradation of the intact radiotracers, as well as CYP isoform- and substrate-specific differences in their metabolic profiles. HepG2 CYP2C19 proved to be the cell line showing the highest metabolic turnover for each radiotracer studied here. Comparison with human and murine liver microsome assays showed good agreement with the human metabolite profile obtained by the HepG2 cell lines. Therefore, CYP-overexpressing HepG2 cells provide a good complement for assessing the metabolic stability of radiotracers and allow the analysis of the CYP isoform-specific contribution to the overall radiotracer metabolism.

Androgen Receptor Stimulates Hexokinase 2 and Induces Glycolysis by PKA/CREB Signaling in Hepatocellular Carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) escapes growth inhibition by upregulating hexokinase 2 (HK2); however, the mechanism by which tumor cells upregulate HK2 remains unclear.

AIM

We aimed to investigate the role of androgen receptor (AR) signalling in promoting HK2 expression in HCC.

METHODS

The expressions of AR and HK2 in HCC tissues were analyzed by immunohistochemistry. Cell proliferation was determined using the CCK-8 assay, and the molecular mechanism of AR in the regulation of HK2 was evaluated by immunoblotting and luciferase assays.

RESULTS

AR expression is positively correlated with HK2 staining by an immunohistochemical analysis. The manipulation of AR expression changed HK2 expression and glycolysis. AR signaling promoted the growth of HCC by enhancing HK2-mediated glycolysis. Moreover, AR stimulated HK2 levels and glycolysis by potentiating protein kinase A/cyclic adenosine monophosphate response element-binding (CREB) protein signaling. CREB silencing decreased HK2 expression and inhibited AR-mediated HCC glycolysis. AR affected the sensitivity of HCC cells to glycolysis inhibitors by regulating downstream phosphorylated (p)-CREB.

CONCLUSIONS

These results indicate that AR at least partially induced glycolysis via p-CREB regulation of HK2 in HCC cells. Thus, this pathway should be considered for the design of novel therapeutic methods to target AR-overexpressing HCC.

Estrogen-induced epigenetic silencing of FTH1 and TFRC genes reduces liver cancer cell growth and survival

Estrogen (E2) regulates hundreds of genes involved in cell metabolism and disrupts iron homoeostasis in various cell types. Herein, we addressed whether E2-induced epigenetic modifications are involved in modulating the expression of iron-regulatory genes. Epigenetic status of FTH1 and TFRC genes was assessed in E2-treated cancer cells. E2-induced DNA methylation was associated with decreased FTH1 and TFRC expression in Hep-G2 and Huh7 cells, but not in AGS or MCF7 cells. Demethylation with 5-Aza-2-deoxycytidine upregulated the expression of both these genes in Hep-G2 cells. The expression of DNMT3B, PRMT5, and H4R3me2s increased in E2-treated cells. Chromatin immunoprecipitation showed that E2 treatment recruited PRMT5 and H4R3me2s on FTH1 but not on TFRC. Knockdown of PRMT5, DNMT3B, and Estrogen-receptor alpha rescued FTH1 from E2-induced silencing. However, knockdown of DNMT3B alone blocked the inhibitory effects of E2 on TFRC. Analysis of human liver tissues in publicly available datasets showed that FTH1 and TFRC are highly expressed in primary liver tumours, but a lower expression is associated with better survival. Interestingly, we showed that the silencing of FTH1 and/or TFRC inhibited carcinogenesis in Hep-G2 cells. For the first time, our findings uncovered the novel signalling pathway involved in the protective effects of E2 against liver cancer.

The effects of estradiol on inflammatory and endothelial dysfunction in rats with preeclampsia

Preeclampsia (PE), a hypertensive disorder during pregnancy, has adverse effects to both the mother and the fetus. Maternal inflammatory and vascular endothelial dysfunction are important factors in the pathogenesis of PE. The present study aimed to investigate the effects of estradiol (E2) on inflammatory and endothelial dysfunction in an N (omega)-nitro-L-arginine methyl ester (L-NAME)-induced rat model of PE. Adult pregnant female Sprague-Dawley rats were divided into four equal groups between days 7 and 11 of gestation and treated as follows: i) Pregnant rats receiving daily intraperitoneal (i.p.) injections of equal volume of 0.9% normal saline (NS) (Control group, n=12); ii) pregnant rats receiving daily i.p. injections of L-NAME at 50 mg/kg (L-NAME group, n=12); iii) pregnant rats receiving a daily i.p. injection of 50 mg/kg L-NAME and NS from day 11 (L-NAME + NS group, n=12); and iv) pregnant rats receiving daily i.p. injections of 50 mg/kg L-NAME and 100 µg/kg/day E2 from day 11 (L-NAME + E2 group, n=12). On day 21, blood pressure (BP) and the level of 24-h urine protein in the maternal rats, fetal weight and percentage of stillbirths following a cesarean section were recorded. The activities of nitric oxide (NO) and inducible NO synthase (iNOS), the levels of inflammatory cytokines [interleukin (IL)-1β, IL-6, interferon-γ and monocyte chemoattractant protein-1], adherence factors (CD49d, intracellular adhesion molecule 1 and lymphocyte function-associated antigen-1) and uterine angiogenic status (Fms-like tyrosine kinase-1, vascular cell adhesion molecule and matrix metalloproteinase 2/9) were also assessed. In addition, the histopathology of the placenta, the expression of estrogen receptor α 36 (ERα36), ERα, ERβ and G protein-coupled ER, as well as the activation of the toll-like receptor 4 (TLR4) signaling pathway (TLR4, myeloid differentiation primary response 88, IL-1 receptor-associated kinase 4 and tumor necrosis factor receptor-associated factor 6) were evaluated by H&E staining, immunofluorescence and western blot assays. Treatment with L-NAME increased the BP, urine protein and rate of stillbirths and suppressed fetal weight compared with those in the control group. The L-NAME-induced effects were attenuated by the administration of E2. In addition, the administration of E2 decreased inflammation and NO levels and altered the uterine angiogenic status. The histological analysis of PE rat placenta in the E2-treated group confirmed the effects on biochemical parameters. Of note, E2 treatment significantly suppressed the TLR4 signaling pathway. In the rat model of PE, adverse outcomes including BP, fetal rat weight and proteinuria, high neonatal death rate, inflammatory response, oxidative stress and endothelial dysfunction were attenuated by exogenous E2 administration, which may present a novel approach for the clinical treatment of PE.

Hepatic copper and other trace mineral concentrations in dogs with hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the most common primary liver tumor in dogs. Abnormalities in hepatic copper, iron, zinc, and selenium concentrations increase risk for HCC development in other species, but trace mineral concentrations have not been evaluated in dogs with HCC.

Objectives

To investigate hepatic trace mineral concentrations in dogs with HCC.

Animals

Archived liver specimens from 85 dogs with HCC and 85 control dogs.

Methods

Retrospective case‐control study. A histopathology database was searched to identify dogs with HCC (test population) and an age‐matched control population. Demographic information was retrieved, and H&E and rhodanine stained slides were reviewed for all cases. Copper, iron, zinc, and selenium concentrations were determined in noncancerous liver tissues (test and control population) and in HCC tissues (test population) using inductively coupled plasma mass spectrometry.

Results

Hepatic copper concentrations (non‐neoplastic hepatic tissue) were greater in test population dogs (median, IQR; 294.9 μg/g, 233.5‐475.9 μg/g) than in control dogs (202.8 μg/g, 135.0‐295.3 μg/g; P < .001). Hepatic zinc concentrations in test (132.1 μg/g,108.6‐163.2 μg/g) and control dogs (151.5 μg/g, 117.1‐184.5 μg/g) also were different (P = .03). Within test population dogs, all trace mineral concentrations were decreased in the HCC tissue as compared to the non‐neoplastic hepatic tissue (all P < .001).

Conclusions and Clinical Importance

Hepatic copper accumulation and other abnormalities in hepatic trace mineral concentrations could be involved in the pathogenesis of HCC in some dogs.