Suppression of AKT anti-apoptotic signaling by a novel drug candidate results in growth arrest and apoptosis of hepatocellular carcinoma cells

Eriocalyxin B Induces Apoptosis and Autophagy Involving Akt/Mammalian Target of Rapamycin (mTOR) Pathway in Prostate Cancer Cells

Background

Eriocalyxin B (EriB), a diterpenoid isolated from the plant Isodon eriocalyx, has been shown to possess anti-tumor properties. However, few systematic studies of the mechanism underlying the anti-tumor activity of Eriocalyxin B in prostate cancer cells have been published. The aim of this study was to investigate the effect of Eriocalyxin B on prostate cancer cells.

Material/Methods

In the present study, the PC-3 (androgen-independent) and 22RV1 (androgen-dependent) human prostate cancer cell lines were cultured with and without increasing doses of Eriocalyxin B. MTT assay was used to measure cell viability. Western blotting was performed to measure levels of proteins associated with apoptosis and autophagy. Flow cytometry was used to assess changes in cell apoptosis and cycle. Fluorescence microscopy was used to capture images of autophagy-related proteins.

Results

Treatment of human prostate cancer cells with Eriocalyxin B resulted in apoptosis in a dose- and time-dependent manner. Eriocalyxin B also induced autophagy, with elevated LC3B-II protein expression and punctuate patterns. Additionally, autophagy protected prostate cancer cells from apoptosis induced by Eriocalyxin B, which was demonstrated by addition of chloroquine (CQ). Moreover, the results indicated that Eriocalyxin B could inhibit the phosphorylation of Akt and mTOR. Eriocalyxin B induced apoptosis and autophagy by inhibition of the Akt/mTOR pathway.

Conclusions

Eriocalyxin B induces apoptosis and autophagy involving the Akt/mTOR pathway in prostate cancer cells in vitro. These findings provide evidence for Eriocalyxin B as a potent therapeutic for the treatment of prostate cancer.

Innovation for hepatotoxicity in vitro research models: A review

Many categories of drugs can induce hepatotoxicity, so improving the prediction of toxic drugs is important. In vitro models using human hepatocytes are more accurate than in vivo animal models. Good in vitro models require an abundance of metabolic enzyme activities and normal cellular polarity. However, none of the in vitro models can completely simulate hepatocytes in the human body. There are two ways to overcome this limitation: enhancing the metabolic function of hepatocytes and changing the cultural environment. In this review, we summarize the current state of research, including the main characteristics of in vitro models and their limitations, as well as improved technology and developmental prospects. We hope that this review provides some new ideas for hepatotoxicity research.

Rhodium (II) complex with 2-benzoylpyridine, a novel potential chemotherapeutic drug, induces cell cycle arrest and apoptosis in HepG2 cells

Rhodium (II) complex with 2-benzoylpyridine (Rh(L)₂Cl₂) is a new, synthetic, active metal-complex, which is produced by the reaction of 2-benzoylpyridine (L) with rhodium chloride hydrate (RhCl₃·nH₂O). The crystal structure was determined by X-ray diffraction which is mono-nuclear. In order to explore the biological properties of the novel complex, a series of studies were performed. The results showed that Rh(L)₂Cl₂ had the anti-tumor activity in HepG₂ and other cell lines and has been shown to induce G1 cell cycle arrest and apoptosis in HepG₂ cells. The anti-cancer effect of Rh(L)₂Cl₂ is regulated by increased expression of caspase-3 and PARP via the mitochondrial and the death receptor pathways. Bcl-2 family proteins might play an important role in the Rh(L)₂Cl₂-induced changes in these two pathways. Further studies indicated that Rh(L)₂Cl₂ increased the level of reactive oxygen species (ROS), but that Rh(L)₂Cl₂-induced apoptosis was ROS-independent. In conclusion, Rh(L)₂Cl₂ is a potential new anti-tumor drug, which induces HepG₂ cell death via the mitochondrial and death receptor pathways and has no obvious toxicity to normal liver cell.

Induction of apoptosis and proliferation inhibition of hepatocellular carcinoma by 6-chloro-2-methoxy-N-(phenylmethyl)-9-acridinamine (BA): in vitro and vivo studies

BACKGROUND

6-Chloro-2-methoxy-N-(phenylmethyl)-9-acridinamine (BA), a novel sponge-derived compound, has been reported to elicit a cytotoxic effect by inhibiting cell proliferation.

METHODS

In this study, we investigated the anti-tumor effect of BA in human hepatocellular carcinoma (HCC) in vitro and in vivo using SMMC-7721 cells. The impact of BA on SMMC-7721 cells was determined by proliferation (clonogenicity and MTT), apoptosis (flow cytometry with annexin V-FITC labeling) and tumor cell migration (Transwell). Apoptosis-related molecules in the PI3K/AKT signaling pathway were examined via Western blotting. We also evaluated the effects of BA on tumor growth using a xenograft nude mouse model.

RESULTS

The data showed that BA induced dose-dependent cytotoxicity, anti-proliferation, anti-migration and apoptosis in SMMC-7721 cells, accompanied by activation of caspase-3 and a decreased level of caspase-9. Moreover, BA decreased PI3K and p-AKT levels, which indicated the cytotoxicity of BA through the PI3K/Akt pathway. Finally, we confirmed that BA inhibited tumor growth in an HCC xenograft mouse model.

CONCLUSIONS

We concluded that BA induced apoptosis and decreased PI3K and p-AKT expression in human HCC with no effect on the liver, kidney, spleen or lungs. These findings suggest that BA could provide a novel strategy for the treatment of HCC.

Novel substituted aminothiazoles as potent and selective anti-hepatocellular carcinoma agents

Based on our previous identification of a disubstituted aminothiazole termed HBF-0079 with promising selective toxicity for HCC-derived cell lines versus non-HCC liver lines, a series of tri-substituted aminothiazole derivatives were prepared and evaluated. This work resulted in the discovery of isopropyl 4-(pyrazin-2-yl)-2-(pyrimidin-2-ylamino)thiazole-5-carboxylate, 14, which displayed EC50 value of 0.11μM and more than 450times of selectivity, and its methyl carbonate prodrug 24 with improved solubility in organic solvents. Furthermore, 14, was shown to reduce the proliferation of several liver cancer cells derived directly from patients.

Rapamycin and fructose-1,6-bisphosphate reduce the HEPG2 cell proliferation via increase of free radicals and apoptosis

Hepatocellular carcinoma is the most prevalent type of tumor among primary tumors affecting the liver. Rapamycin is currently used as a basis for chemotherapy in the treatment of cancers, including the liver. Because it shows several adverse effects, minimizing these effects without compromising efficacy is important. In this sense other drugs may be used concomitantly. One of these drugs is fructose-1,6-bisphosphate (FBP), which has shown therapeutic effect in various pathological situations, having antioxidant and anti-inflammatory proprieties. The objective of the present study was to evaluate the activity of rapamycin in combination with the FBP in HepG2 cell proliferation and the mechanisms involved. HepG2 cells were analyzed after 72 h of treatment with both drugs. Cell proliferation, cytotoxicity, cytokines, apoptosis, senescence, autophagy and oxidative stress were accessed. Ιt was demonstrated that the combination is more efficient than the single use of substances, because subtherapeutic doses of rapamycin, when associated to FBP become effective, reducing cell proliferation, through a significant increase in the production of tiobarbituric acid reactive substances (TBARS), suggesting that this might be the cause of death by apoptosis. According to these results, we believe that the association of both drugs may be a promising choice for the treatment of hepatocarcinoma.

Doxorubicin induces apoptosis by targeting Madcam1 and AKT and inhibiting protein translation initiation in hepatocellular carcinoma cells

Doxorubicin (Doxo) is one of the most widely used chemotherapeutic drugs for patients with hepatocellular carcinoma (HCC). Doxo is a DNA intercalating drug that inhibits topoisomerase II. Thereby Doxo has the ability to block DNA replication and induce apoptosis. However, the other targets and mechanisms through which Doxo induces apoptosis to treat HCC still remain unknown. Here, we identified Mucosal vascular addressin cell adhesion molecule 1 (Madcam1) as a potential Doxo target because Madcam1 overexpression suppressed, while Madcam1 depletion stimulated Doxo-induced apoptosis. Furthermore, we first revealed that Doxo can induce apoptosis by blocking protein translation initiation. In contrast, Madcam1 activated protein translation through an opposite mechanism. We also found de-phosphorylation of AKT may be an important pro-apoptotic event that is triggered by Doxo-induced Madcam1 down-regulation. Finally, we revealed that Madcam1 promoted increased AKT phosphorylation, which is essential for maintaining the sensitivity of HCC cells to Doxo treatment. Taken together, we uncovered a potential mechanism for Doxo-induced apoptosis in HCC treatment through targeting Madcam1 and AKT and blocking protein translation initiation.

RPPA-based protein profiling reveals eIF4G overexpression and 4E-BP1 serine 65 phosphorylation as molecular events that correspond with a pro-survival phenotype in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL), the most common adult leukemia, remains incurable despite advancements in treatment regimens over the past decade. Several expression profile studies have been pursued to better understand CLL pathogenesis. However, these large-scale studies only provide information at the transcriptional level. To better comprehend the differential protein changes that take place in CLL, we performed a reverse-phase protein array (RPPA) analysis using 167 different antibodies on B-cell lysates from 18 CLL patients and 6 normal donors. From our analysis, we discovered an enrichment of protein alterations involved with mRNA translation, specifically upregulation of the translation initiator eIF4G and phosphorylation of the cap-dependent translation inhibitor 4E-BP1 at serine 65. Interestingly, 4E-BP1 phosphorylation occurred independently of AKT phosphorylation, suggesting a disconnect between PI3K/AKT pathway activation and 4E-BP1 phosphorylation. Based on these results, we treated primary CLL samples with NVP-BEZ235, a PI3K/mTOR dual inhibitor, and compared its apoptotic-inducing potential against the BTK inhibitor Ibrutinib and the PI3Kδ inhibitor Idelalisib. We demonstrated that treatment with NVP-BEZ235 caused greater apoptosis, greater apoptotic cleavage of eIF4G, and greater dephosphorylation of 4E-BP1 in primary CLL cells. Taken together, these results highlight the potential dependence of eIF4G overexpression and 4E-BP1 phosphorylation in CLL survival.

Genetic deletion and pharmacological inhibition of Akt1 isoform attenuates bladder cancer cell proliferation, motility and invasion

Isoform specific expression, intracellular localization and function of Akt in bladder cancer are not known. In the current study, we identified Akt1, followed by Akt2 and Akt3 as the predominant Akt isoform in human T24 and UM-UC-3 metastatic bladder cancer cells. Whereas Akt1 is localized at the membrane, cytoplasm and nucleus, Akt2 is solely cytoplasmic and Akt3 is mostly localized in the nucleus in T24 cells. ShRNA-mediated Akt1 knockdown resulted in impaired T24 cell survival, proliferation, colony formation, migration and microinvasion. Whereas pharmacological inhibition of Akt1 resulted in impaired T24 and UM-UC-3 cell motility, viability and proliferation, effect of pharmacological inhibition by Akt2 inhibitor was limited to proliferation in T24, but not UM-UC-3 cells. Our data provide important clues on the therapeutic benefits of targeting Akt1 for bladder cancer therapy.

β-Arrestin1 enhances hepatocellular carcinogenesis through inflammation-mediated Akt signalling

G-protein-coupled receptors (GPCR) constitute the largest known superfamily for signal transduction and transmission, and they control a variety of physiological and pathological processes. GPCR adaptor β-arrestins (ARRBs) play a role in cancerous proliferation. However, the effect of ARRBs in inflammation-mediated hepatocellular carcinogenesis is unknown. Here we show that ARRB1, but not ARRB2, is upregulated in inflammation-associated hepatocellular carcinoma (HCC) and paracancerous tissues in humans. A genotoxic carcinogen, diethylnitrosamine (DEN), significantly induces hepatic inflammation, TNF-α production and ARRB1 expression. Although ARRB1 deficiency does not affect hepatic inflammation and TNF-α production, it markedly represses hepatocellular carcinogenesis by suppressing malignant proliferation in DEN-treated mice. Furthermore, TNF-α directly induces hepatic ARRB1 expression and enhances ARRB1 interaction with Akt by binding to boost Akt phosphorylation, resulting in malignant proliferation of liver cells. Our data suggest that ARRB1 enhances hepatocellular carcinogenesis by inflammation-mediated Akt signalling and that ARRB1 may be a potential therapeutic target for HCC.

The critical molecular interconnections in regulating apoptosis and autophagy

Apoptosis and autophagy are both highly regulated biological processes that have important roles in development, differentiation, homeostasis, and disease. These processes may take place independently, with autophagy being cytoprotective for preventing cells from apoptosis and apoptosis blocking autophagy. But in most circumstances, both may be induced sequentially with autophagy preceding apoptosis. The simultaneous activation of both processes has been observed not only in experimental settings but also in pathophysiological conditions. In fact, these two pathways are tightly connected with each other by substantial interplays between them, enabling the coordinated regulation of cell fates by these two pathways. They share some common upstream signaling components, and some components of one pathway may play important roles in the other, and vice versa. Such proteins represent the critical interconnections of the two pathways, which seem to determine the cell for survival or death. Here several critical molecular interconnections between apoptosis and autophagy pathways are reviewed, with their action mechanisms being highlighted.

Immortalized Human Hepatic Cell Lines for In Vitro Testing and Research Purposes

The ubiquitous shortage of primary human hepatocytes has urged the scientific community to search for alternative cell sources, such as immortalized hepatic cell lines. Over the years, several human hepatic cell lines have been produced, whether or not using a combination of viral oncogenes and human telomerase reverse transcriptase protein. Conditional approaches for hepatocyte immortalization have also been established and allow generation of growth-controlled cell lines. A variety of immortalized human hepatocytes have already proven useful as tools for liver-based in vitro testing and fundamental research purposes. The present chapter describes currently applied immortalization strategies and provides an overview of the actually available immortalized human hepatic cell lines and their in vitro applications.

Lycopene metabolite, apo-10'-lycopenoic acid, inhibits diethylnitrosamine-initiated, high fat diet-promoted hepatic inflammation and tumorigenesis in mice

Obesity is associated with increased risk in hepatocellular carcinoma (HCC) development and mortality. An important disease control strategy is the prevention of obesity-related hepatic inflammation and tumorigenesis by dietary means. Here, we report that apo-10'-lycopenoic acid (APO10LA), a cleavage metabolite of lycopene at its 9',10'-double bond by carotene-9',10'-oxygenase, functions as an effective chemopreventative agent against hepatic tumorigenesis and inflammation. APO10LA treatment on human liver THLE-2 and HuH7 cells dose dependently inhibited cell growth and upregulated sirtuin 1 (SIRT1), a NAD(+)-dependent protein deacetylase that may suppress hepatic carcinogenesis. This observed SIRT1 induction was associated with decreased cyclin D1 protein, increased cyclin-dependent kinase inhibitor p21 protein expression, and induced apoptosis. APO10LA supplementation (10 mg/kg diet) for 24 weeks significantly reduced diethylnitrosamine-initiated, high fat diet (HFD)-promoted hepatic tumorigenesis (50% reduction in tumor multiplicity; 65% in volume) and lung tumor incidence (85% reduction) in C57Bl/6J mice. The chemopreventative effects of APO10LA were associated with increased hepatic SIRT1 protein and deacetylation of SIRT1 targets, as well as with decreased caspase-1 activation and SIRT1 protein cleavage. APO10LA supplementation in diet improved glucose intolerance and reduced hepatic inflammation [decreased inflammatory foci, TNFα, interleukin (IL)-6, NF-κB p65 protein expression, and STAT3 activation] in HFD-fed mice. Furthermore, APO10LA suppressed Akt activation, cyclin D1 gene, and protein expression and promoted PARP protein cleavage in transformed cells within liver tumors. Taken together, these data indicate that APO10LA can effectively inhibit HFD-promoted hepatic tumorigenesis by stimulating SIRT1 signaling while reducing hepatic inflammation.