Hexavalent chromium exposure activates the non-canonical nuclear factor kappa B pathway to promote immune checkpoint protein programmed death-ligand 1 expression and lung carcinogenesis.

Lung cancer is the leading cause of cancer-related death worldwide; however, the mechanism of lung carcinogenesis has not been clearly defined. Chronic exposure to hexavalent chromium [Cr(VI)], a common environmental and occupational pollutant, causes lung cancer, representing an important lung cancer etiology factor. The mechanism of how chronic Cr(VI) exposure causes lung cancer remains largely unknown. By using cell culture and mouse models and bioinformatics analyses of human lung cancer gene expression profiles, this study investigated the mechanism of Cr(VI)-induced lung carcinogenesis. A new mouse model of Cr(VI)-induced lung carcinogenesis was developed as evidenced by the findings showing that a 16-week Cr(VI) exposure (CaCrO4, 100 µg per mouse once per week) via oropharyngeal aspiration induced lung adenocarcinomas in male and female A/J mice, whereas none of the sham-exposed control mice had lung tumors. Mechanistic studies revealed that chronic Cr(VI) exposure activated the non-canonical NFκB pathway through the long non-coding RNA (lncRNA) ABHD11-AS1/deubiquitinase USP15-mediated tumor necrosis factor receptor-associated factor 3 (TRAF3) down-regulation. The non-canonical NFκB pathway activation increased the interleukin 6 (IL-6)/Janus kinase (Jak)/signal transducer and activator of transcription 3 (Stat3) signaling. The activation of the IL-6/Jak signaling axis by Cr(VI) exposure not only promoted inflammation but also stabilized the immune checkpoint molecule programmed death-ligand 1 (PD-L1) protein in the lungs, reducing T lymphocyte infiltration to the lungs. Given the well-recognized critical role of PD-L1 in inhibiting anti-tumor immunity, these findings suggested that the lncRNA ABHD11-AS1-mediated non-canonical NFκB pathway activation and PD-L1 up-regulation may play important roles in Cr(VI)-induced lung carcinogenesis.

Long noncoding RNA ABHD11-AS1 interacts with SART3 and regulates CD44 RNA alternative splicing to promote lung carcinogenesis.

Hexavalent chromium [Cr(VI)] is a common environmental pollutant and chronic exposure to Cr(VI) causes lung cancer in humans, however, the mechanism of Cr(VI) carcinogenesis has not been well understood. Lung cancer is the leading cause of cancer-related death, although the mechanisms of how lung cancer develops and progresses have been poorly understood. While long non-coding RNAs (lncRNAs) are found abnormally expressed in cancer, how dysregulated lncRNAs contribute to carcinogenesis remains largely unknown. The goal of this study is to investigate the mechanism of Cr(VI)-induced lung carcinogenesis focusing on the role of the lncRNA ABHD11 antisense RNA 1 (tail to tail) (ABHD11-AS1). It was found that the lncRNA ABHD11-AS1 expression levels are up-regulated in chronic Cr(VI) exposure-transformed human bronchial epithelial cells, chronically Cr(VI)-exposed mouse lung tissues, and human lung cancer cells as well. Bioinformatics analysis revealed that ABHD11-AS1 levels are up-regulated in lung adenocarcinomas (LUADs) tissues and associated with worse overall survival of LUAD patients but not in lung squamous cell carcinomas. It was further determined that up-regulation of ABHD11-AS1 expression plays an important role in chronic Cr(VI) exposure-induced cell malignant transformation and tumorigenesis, and the stemness of human lung cancer cells. Mechanistically, it was found that ABHD11-AS1 directly binds SART3 (spliceosome associated factor 3, U4/U6 recycling protein). The interaction of ABHD11-AS1 with SART3 promotes USP15 (ubiquitin specific peptidase 15) nuclear localization. Nuclear localized USP15 interacts with pre-mRNA processing factor 19 (PRPF19) to increase CD44 RNA alternative splicing activating ß-catenin and enhancing cancer stemness. Together, these findings indicate that lncRNA ABHD11-AS1 interacts with SART3 and regulates CD44 RNA alternative splicing to promote cell malignant transformation and lung carcinogenesis.

Epigenetic downregulation of O6-methylguanine-DNA methyltransferase contributes to chronic hexavalent chromium exposure-caused genotoxic effect and cell transformation.

Hexavalent chromium [Cr(VI)] is a common environmental pollutant and chronic exposure to Cr(VI) causes lung cancer and other types of cancer in humans, although the mechanism of Cr(VI) carcinogenesis remains elusive. Cr(VI) has been considered as a genotoxic carcinogen, but accumulating evidence indicates that Cr(VI) also causes various epigenetic toxic effects that play important roles in Cr(VI) carcinogenesis. However, it is not clear how Cr(VI)-caused epigenetic dysregulations contributes to Cr(VI) carcinogenesis. This study investigates whether Cr(VI) epigenetic toxic effect has an impact on its genotoxic effect. It was found that chronic low dose of Cr(VI) exposure time-dependently down-regulates the expression of a critical DNA damage repair protein O6-methylguanine-DNA methyltransferase (MGMT), leading to the increases of the levels of the highly mutagenic and carcinogenic DNA lesion O6-methylguanine (O6-MeG) in human bronchial epithelial BEAS-2B cells. Moreover, the levels of MGMT and O6-MeG in chronic Cr(VI) exposure-caused human lung cancer tissues are also significantly lower and higher than that in the adjacent normal lung tissues, respectively. It was further determined that chronic low dose of Cr(VI) exposure-transformed BEAS-2B cells display impaired DNA damage repair capacity and a high sensitivity to the toxicity of the alkylating chemotherapeutic drug Temozolomide. In contrast, stably overexpressing MGMT in parental BEAS-2B cells reverses chronic low dose of Cr(VI) exposure-caused DNA damage repair deficiency and significantly reduces cell transformation by Cr(VI). Further mechanistical studies revealed that chronic low dose of Cr(VI) exposure down-regulates MGMT expression through epigenetic mechanisms by increasing DNA methylation and histone H3 repressive modifications. Taken together, these findings suggest that epigenetic down-regulation of a crucial DNA damage repair protein MGMT contributes significantly to the genotoxic effect and cell transformation caused by chronic low dose of Cr(VI) exposure.

Up-regulation of RNA m6A methyltransferase like-3 expression contributes to arsenic and benzo[a]pyrene co-exposure-induced cancer stem cell-like property and tumorigenesis.

While arsenic or BaP alone exposure can cause lung cancer, studies showed that arsenic plus BaP co-exposure displays a significantly stronger lung tumorigenic effect. However, the underlying mechanism has not been well understood. Studies showed that RNA molecules are chemically modified. The most frequently occurring RNA modification in eukaryotic messenger RNAs is the N6-methyladenosine (m6A) methylation. This study aimed to determine whether arsenic plus BaP exposure alters RNA m6A methylation and its role in lung tumorigenic effect of arsenic plus BaP exposure. Human bronchial epithelial cells transformed by exposure to arsenic or BaP alone, and arsenic plus BaP and mouse xenograft tumorigenesis models were used in this study. It was found that arsenic plus BaP exposure-transformed cells have significantly higher levels of RNA m6A methylation than arsenic or BaP alone exposure-transformed human bronchial epithelial cells. Western blot analysis showed that arsenic plus BaP exposure greatly up-regulates the m6A writer methyltransferase like-3 (METTL3) expression levels in cultured cells and mouse lung tissues. METTL3 knockdown in cells transformed by arsenic plus BaP exposure drastically reduced their RNA m6A methylation levels. Functional studies revealed that METTL3 knockdown in cells transformed by arsenic plus BaP exposure greatly reduces their anchorage-dependent and -independent growth, cancer stem cell characters and tumorigenesis. The findings from this study suggest that arsenic plus BaP co-exposure causes epitranscriptomic dysregulation, which may contribute significantly to arsenic plus BaP co-exposure-caused synergistic lung tumorigenic effect.

Mechanisms of Smoothened Regulation in Hedgehog Signaling.

The seven-transmembrane protein, Smoothened (SMO), has shown to be critical for the hedgehog (HH) signal transduction on the cell membrane (and the cilium in vertebrates). SMO is subjected to multiple types of post-translational regulations, including phosphorylation, ubiquitination, and sumoylation, which alter SMO intracellular trafficking and cell surface accumulation. Recently, SMO is also shown to be regulated by small molecules, such as oxysterol, cholesterol, and phospholipid. The activity of SMO must be very well balanced by these different mechanisms in vivo because the malfunction of SMO will not only cause developmental defects in early stages, but also induce cancers in late stages. Here, we discuss the activation and inactivation of SMO by different mechanisms to better understand how SMO is regulated by the graded HH signaling activity that eventually governs distinct development outcomes.

Combating acquired resistance to MAPK inhibitors in melanoma by targeting Abl1/2-mediated reactivation of MEK/ERK/MYC signaling.

Metastatic melanoma remains an incurable disease for many patients due to the limited success of targeted and immunotherapies. BRAF and MEK inhibitors reduce metastatic burden for patients with melanomas harboring BRAF mutations; however, most eventually relapse due to acquired resistance. Here, we demonstrate that ABL1/2 kinase activities and/or expression are potentiated in cell lines and patient samples following resistance, and ABL1/2 drive BRAF and BRAF/MEK inhibitor resistance by inducing reactivation of MEK/ERK/MYC signaling. Silencing/inhibiting ABL1/2 blocks pathway reactivation, and resensitizes resistant cells to BRAF/MEK inhibitors, whereas expression of constitutively active ABL1/2 is sufficient to promote resistance. Significantly, nilotinib (2nd generation ABL1/2 inhibitor) reverses resistance, in vivo, causing prolonged regression of resistant tumors, and also, prevents BRAFi/MEKi resistance from developing in the first place. These data indicate that repurposing the FDA-approved leukemia drug, nilotinib, may be effective for prolonging survival for patients harboring BRAF-mutant melanomas.

A combination of astragaloside I, levistilide A and calycosin exerts anti-liver fibrosis effects in vitro and in vivo.

Liver fibrosis is excessive accumulation of extracellular matrix proteins that results from various chronic liver diseases. Hepatic stellate cells (HSCs) play an essential role in the pathogenesis of liver fibrosis. Danggui Buxue Tang (DBT) is a classic formula of Chinese traditional medicine. We previously showed that DBT could ameliorate liver fibrosis in rats. However, the bioactive components of DBT in the treatment of liver fibrosis remain unknown. In this study we evaluated 14 ingredients from DBT in human hepatic stellate cell line LX-2, and found that astragaloside I (A), levistilide A (L) and calycosin (C) produced synergistic proliferation inhibition on LX-2 cells and TGF-ß1-activated LX-2 cells. Thus, we prepared a mixture of them, and named this combination as ALC formula. Using high-content screening and Western blot assay we revealed that the ALC formula significantly reduced the expression of α-SMA and collagen I in LX-2 cells. The in vivo anti-fibrosis effects of ALC formula were evaluated in a liver fibrosis model in C57BL/6 mice established through injection of dimethylnitrosamine (DMN 2 mg/kg, ip) for 4 weeks. In the third week, the nice were injected with ALC formula (astragaloside I 44.21 mg/kg per day, levistilide A 6 mg/kg per day and calycosin 3.45 mg/kg per day; ip) or sorafenib, a positive control drug (6 mg/kg per day, ip) for 2 weeks. We found that administration of the ALC formula markedly decreased collagen deposition, hydroxyproline (Hyp) content and α-SMA expression levels in the liver tissues compared to the model mice. In conclusion, the present study demonstrates for the first time that astragaloside I, levistilide A and calycosin may be the 3 main bioactive components in DBT; their combination exerts anti-liver fibrosis effects in vitro and in vivo.

Pyramidatine (Z88) Sensitizes Vincristine-Resistant Human Oral Cancer (KB/VCR) Cells to Chemotherapeutic Agents by Inhibition of P-glycoprotein.

BACKGROUND: Multi-drug resistance (MDR) remains a major impediment in cancer therapy. A major goal for scientists is to discover more effective compounds that are able to circumvent MDR and simultaneously have minimal adverse side effects. OBJECTIVE: In the present study, we aim to determine the anti-MDR effects of pyramidatine (Z88), a cinnamic acid-derived bisamide compound isolated from the leaves of Aglaia perviridis, on KB/VCR (vincristineresistant human oral cancer cells) and MCF-7/ADR (adriamycin-resistant human breast adenocarcinoma) cells. METHODS: Cell viability and average resistant fold (RF) of Z88 were examined by Cell Counting Kit-8 (CCK-8) assay. Flow cytometry, western blot, RT-PCR, Rhodamine 123 accumulation assay and P-glycoprotein (P-gp) ATPase assay were used to demonstrate the anti-MDR activity and mechanism of Z88. RESULTS: The average RF of Z88 is 0.09 and 0.51 in KB/VCR and MCF-7/ADR cells. A CCK-8 assay showed that Z88 could enhance the cytotoxicity of VCR toward KB/VCR cells. A FACS analysis revealed that Z88 could enhance the VCR-induced apoptosis as well as G2/M arrest in a dose-dependent manner in KB/VCR cells. Western blot results showed that the expression levels of PARP, Bax, and cyclin B1 all increased after treatment with 0.2 µmol/L (µM) of VCR combined with 10 µM of Z88 for 24 h in KB/VCR cells. Z88 also could enhance the accumulation of rhodamine 123. Further studies showed that Z88 could inhibit the verapamil stimulated Pgp ATPase activity. Additionally, qPCR detection and western blot assays revealed that Z88 could decrease the expression of P-gp at both RNA and protein level. CONCLUSION: Z88 exerted potent anti-MDR activity in vitro and its mechanisms are associated with dualinhibition of the function and expression of P-gp. These findings encourage efforts to develop more effective reversal agents to circumvent MDR based on Z88.

EnABLing Tumor Growth and Progression: Recent progress in unraveling the functions of ABL kinases in solid tumor cells.

PURPOSE OF REVIEW: The goal of this review is to summarize our current knowledge regarding how ABL family kinases are activated in solid tumors and impact on solid tumor development/progression, with a focus on recent advances in the field. RECENT FINDINGS: Although ABL kinases are known drivers of human leukemia, emerging data also implicates the kinases in a large number of solid tumor types where they promote diverse processes such as proliferation, survival, cytoskeletal reorganization, cellular polarity, EMT (epithelial-mesenchymal-transition), metabolic reprogramming, migration, invasion and metastasis via unique signaling pathways. ABL1 and ABL2 appear to have overlapping but also unique roles in driving these processes. In some tumor types, the kinases may act to integrate pro- and anti-proliferative and -invasive signals, and also may serve as a switch during EMT/MET (mesenchymal-epithelial) transitions. CONCLUSIONS: Most data indicate that targeting ABL kinases may be effective for reducing tumor growth and preventing metastasis; however, ABL kinases also may have a tumor suppressive role in some tumor types and in some cellular contexts. Understanding the functions of ABL kinases in solid tumors is critical for developing successful clinical trials aimed at targeting ABL kinases for the treatment of solid tumors.

Glaucocalyxin A inhibits the growth of liver cancer Focus and SMMC-7721 cells.

Liver cancer is one of the most common types of cancer, and hepatoma demonstrates a poor long-term prognosis. The present study reports that glaucocalyxin A (GLA), a natural product isolated from Rabdosia umbrosa, inhibits the growth of the liver cancer Focus and SMMC-7721 cell lines in a dose- and time-dependent manner. The present study revealed that GLA arrested the liver cancer cells at the G2/M stage of the cell cycle and led to decreased expression of caspase 3 and the cleavage of poly(adenosine diphosphate-ribose) polymerase. Overall, the present study demonstrated that GLA inhibits the growth of liver cancer cells by G2/M stage cell-cycle arrest and cell apoptosis.

Ergosterol Is the Active Compound of Cultured Mycelium Cordyceps sinensis on Antiliver Fibrosis.

Cultured mycelium Cordyceps sinensis (CMCS) is a Chinese herbal medicine, which is widely used for a variety of diseases including liver injury in clinic. The current study aims to investigate the protective effects of CMCS against liver fibrosis and to exploit its active antifibrotic substances in vivo and in vitro. For evaluating the antifibrotic effect of CMCS and ergosterol, male C57BL/6 mice were injected intraperitoneally with carbon tetrachloride (CCl4) and treated with CMCS (120 mg/kg/d) or ergosterol (50 mg/kg/d). Four weeks later, serum liver function, hepatic hydroxyproline (Hyp) content, liver inflammation, collagen deposition, and expression of alpha smooth muscle actin (α-SMA) in liver tissue were evaluated. Besides, toxicological effects of active compounds of CMCS on hepatocytes and hepatic stellate cells (HSCs) were detected and expressions of permeability of the lysosomal membrane, EdU, F-actin, and α-SMA of activated HSCs were analyzed to screen the antifibrotic substance in CMCS in vitro. Our results showed that CMCS could significantly alleviate levels of serum liver functions, attenuate hepatic inflammation, decrease collagen deposition, and relieve levels of α-SMA in liver, respectively. Ergosterol, the active compound in CMCS that was detected by HPLC, played a dose-dependent inhibition role on activated HSCs via upregulating expressions of permeability of the lysosomal membrane and downregulating levels of EdU, F-actin, and α-SMA on activated HSCs in vitro. Moreover, ergosterol revealed the antifibrotic effect alike in vivo. In conclusion, CMCS is effective in alleviating liver fibrosis induced by CCl4 and ergosterol might be the efficacious antifibrotic substance in CMCS in vivo and in vitro.

Fuzheng Huayu recipe alleviates hepatic fibrosis via inhibiting TNF-α induced hepatocyte apoptosis.

BACKGROUND: What was the relationship of Fuzheng Huayu recipe (FZHY) inhibiting hepatocyte apoptosis and HSC activation at different stage of liver fibrosis? In order to answer this question, the study was carried out to dynamically observe FZHY's effect on hepatocyte apoptosis and HSC activation and further explored underling mechanism of FZHY against hepatocyte apoptosis. METHODS: Mice were randomly divided into four groups: normal, model, FZHY, and N-acetylcystein (NAC) groups. Acute hepatic injury and liver fibrosis in mice were induced by CCl4. Three days before the first CCl4 injection, treatment with FZHY powder or NAC respectively was started. In vitro, primary hepatocytes were pretreated with FZHY medicated serum or Z-VAD-FMK and then incubated with ActD and TNF-α. Primary HSCs were treated with DNA from apoptotic hepatocytes incubated by Act D/TNF-α or FZHY medicated. Liver sections were analyzed for HE staining and immunohistochemical evaluation of apoptosis. Serum ALT and AST, Alb content and TNF-α expression in liver tissue were detected. Hyp content was assayed and collagen deposition was visualized. Expressions of α-SMA and type I collagen were analyzed by immunofluorescence and immunoblotting. Flow cytometry, immunofluorescence, and DNA ladder for hepatocyte apoptosis and immunoblotting for TNF-R1, Bcl-2 and Bax were also analyzed. RESULTS: Mice showed characteristic features of massive hepatocytes apoptosis in early stage of liver injury and developed severe hepatic fibrosis in later phase. FZHY treatment significantly alleviated acute liver injury and hepatocyte apoptosis, and inhibited liver fibrosis by decreasing α-SMA expression and hepatic Hyp content. In vitro, primary hepatocytes were induced by TNF-α and Act D. The anti-apoptotic effect of FZHY was generated by reducing TNFR1 expression and balancing the expressions of Bcl-2 and Bax. Meanwhile, the nuclear DNA from apoptotic hepatocytes stimulated HSC activation in a dose dependent manner, and the DNA from apoptotic hepatocytes treated with FZHY or Z-VAD-FMK reduced HSC activation and type I collagen expression. CONCLUSION: These findings suggested that FZHY suppressed hepatocyte apoptosis through regulating mediators in death receptor and mitochondrial pathways, and the effect of FZHY on hepatocyte apoptosis might play an important role in inhibiting liver fibrosis.

Reversal of P-gp and MRP1-mediated multidrug resistance by H6, a gypenoside aglycon from Gynostemma pentaphyllum, in vincristine-resistant human oral cancer (KB/VCR) cells.

Multidrug resistance (MDR) to anticancer drugs is a major obstacle to successful chemotherapy in the treatment of cancers. Identification of natural compounds capable of circumventing MDR with minimal adverse side effects is an attractive goal. Here, we found that H6, a gypenoside aglycon from Gynostemma pentaphyllum, displayed potent anti-MDR activity. Average resistant fold (RF) of H6 is 1.03 and 1.04 in KB/VCR and MCF-7/ADR cells compared to their parental cells. H6 alone ranging from 2 µmol/l to 40 µmol/l (µM) did not display a significant anti-proliferative effect on KB/VCR cells and other cells, while the compound at these concentrations enhanced the cytotoxicity of vincristine (VCR) to KB/VCR cells. H6 showed a significant synergistic effect in combination with VCR. By quantification of sub-G(1) fraction cells, H6 also enhanced the VCR-induced apoptosis in a dose-dependent manner. The short time treatment with H6 increased the intracellular accumulation of rhodamine 123 (Rho123) and 5(6)-carboxyfluorescein diacetate (CFDA) in KB/VCR cells. Further studies showed that H6 treatment resulted in the decrease of the RNA transcript level of P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein (BCRP). H6 inhibited the function of P-gp by stimulating P-gp ATPase activity and decreased MRP1 expression with a blockade of STAT3 phosphorylation. These findings suggest that H6, a multi-targets reversal agent with no significant toxic effect, may be a potential candidate to circumvent the P-gp and MRP1-mediated MDR.

A novel sulfonamide agent, MPSP-001, exhibits potent activity against human cancer cells in vitro through disruption of microtubule.

AIM: To evaluate the anti-cancer effects of a new sulfonamide derivative, 2-(N-(3-chlorophenyl)-4-methoxyphenylsulfonamido)-N-hydroxypropanamide (MPSP-001). METHODS: Human cancer cell lines (HepG2, THP-1, K562, HGC-27, SKOV3, PANC-1, SW480, Kba, HeLa, A549, MDA-MB-453, and MCF-7) were examined. The cytotoxicity of MPSP-001 was evaluated using the WST-8 assay. Cell cycle distribution was examined with flow cytometry. Mitotic spindle formation was detected using immunofluorescence microscopy. Apoptosis-related proteins were examined with Western blot using specific phosphorylated protein antibodies. Competitive tubulin-binding assay was performed to test whether the compound competitively bound to the colchicine site. Molecular docking was performed to explore the possible binding conformation. RESULTS: MPSP-001 potently inhibited the growth of the 12 different types of human cancer cells with the IC(50) values ranging from 1.9 to 15.7 µmol/L. The compound exerted potent inhibition on the drug-resistant Kb/VCR and MCF-7/ADR cells, as on Kba and MCF-7 cells. In HeLa, HGC-27, A549, and other cells, the compound (5 µmol/L) caused cell cycle arrest at the G(2)/M phase, and subsequently induced cell apoptosis. In Hela cells, it prevented the mitotic spindle formation. Furthermore, the compound dose-dependently inhibited polymerization of tubulin in vitro, and directly bound to the colchicine-site of ß-tubulin. Molecular docking predicted that the compound may form two hydrogen bonds to the binding pocket. The compound showed synergistic effects with colchicine and taxol in blocking mitosis of HeLa cells. CONCLUSION: MPSP-001 shows a broad-spectrum of anti-tumor efficacy in vitro and represents a novel structure with anti-microtubule activity.

Discovery of novel 2-N-aryl-substituted benzenesulfonamidoacetamides: orally bioavailable tubulin polymerization inhibitors with marked antitumor activities.

The discovery and optimization of a series of 2-N-aryl-substituted benzenesulfonamidoacetamides as novel tubulin polymerization inhibitors are described. Pharmacophore exploration of hit compound AH-487 identified the optimal structure of N-heteroaryl-2-(4-methoxy-N-(3-(trifluoromethyl)phenyl)phenylsulfonamido)acetamide as a potent antimitotic agent. Subsequent lead compounds 4b and 4c, with N-4-aminophenyl and N-1H-indol-5-yl substitutions at the acetamide position, respectively, were shown to induce cell-cycle arrest at the G(2) /M phase and lead to an accumulation of HeLa cells in the sub-G(1) phase. More significantly, these lead compounds (3c, 4b, and 4c) exhibit impressive cytotoxicity against a panel of cancer cells including P-glycoprotein-overexpressing MDR-positive cells, with potency greater than or equal to clinically studied benzenesulfonamide E7010. Mechanistic studies demonstrated that derivatives of AH-487 disrupt mitotic spindles by inhibiting microtubule polymerization and induce apoptosis via induction of Bcl-2 phosphorylation in tumor cells. The optimized leads 4b and 4c strongly inhibited the growth of human hepatocellular carcinoma cells in a mouse xenograft model.

Zinc finger transcription factor 191, directly binding to ß-catenin promoter, promotes cell proliferation of hepatocellular carcinoma.

UNLABELLED: Activation of ß-catenin, the central effector of the canonical wingless-type (Wnt) pathway, has been implicated in hepatocellular carcinoma (HCC). However, the transcription regulation mechanism of the ß-catenin gene in HCC remains unknown. Here we report that human zinc finger protein 191 (ZNF191) is a potential regulator of ß-catenin transcription. ZNF191, a Krüppel-like protein, specifically interacts with the TCAT motif, which constitutes the HUMTH01 microsatellite in the tyrosine hydroxylase (TH) gene ex vivo. We demonstrate that ZNF191 is significantly overexpressed in human HCC specimens and is associated with growth of human HCC cells. Global profiling of gene expression in ZNF191 knockdown human hepatic L02 cells revealed that the important Wnt signal pathway genes ß-catenin and cyclin D1 messenger RNAs (mRNAs) are significantly down-regulated. In agreement with transcription level, ß-catenin and cyclin D1 proteins are also down-regulated in transient and stable ZNF191 knockdown L02 and hepatoma Hep3B cell lines. Moreover, significant correlation between ZNF191 and ß-catenin mRNA expression was detected in human HCCs. Promoter luciferase assay indicated that ZNF191 can increase transcription activity of the full-length ß-catenin (CTNNB1) promoter, and nucleotide (nt)-1407/-907 of the CTNNB1 promoter exhibited the maximum transcriptional activity. Electrophoretic mobility shift assay showed that purified ZNF191 protein can directly bind to the CTNNB1 promoter, and the binding region is located at nt-1254/-1224. Finally, we demonstrate that the key binding sequence of ZNF191 in vivo is ATTAATT. CONCLUSION: ZNF191 can directly bind to the CTNNB1 promoter and activate the expression of ß-catenin and its downstream target genes such as cyclin D1 in hepatoma cell lines. This study uncovers a new molecular mechanism of transcription regulation of the ß-catenin gene in HCC.

Synthesis and utilization of chiral alpha-methylated alpha-amino acids with a carboxyalkyl side chain in the design of novel Grb2-SH2 peptide inhibitors free of phosphotyrosine.

The growth factor receptor-bound protein 2 (Grb2) is an SH2 domain-containing docking module that represents an attractive target for anticancer therapeutic intervention. To improve the potency and bioavailability of the Grb2-SH2 inhibitors, the chiral alpha-methyl-alpha-carboxyalkyl amino acid [(alpha-Me)Aa] was designed to cover dual structural and functional features separately contributed by 1-aminocyclohexanecarboxylic acid (Ac6c) and alpha-aminoadipic acid (Adi) in position Y + 1. The enantiopure l(or D)-(alpha-Me)Aa bearing various chain length carboxylalkyl side chain was conveniently synthesized by an optimized oxazolidinone methodology. The incorporation of (S)-(alpha-Me)Aa into the non-pTyr-containing peptide framework with a 5-amino acid sequence binding motif of X (-2)-Leu-(3'-substituted-Tyr) (0)-X (+1)-Asn really improved the inhibitory activity, affording potent (R)-sulfoxide-bridged cyclic and an open-chain series of pentapeptide inhibitors of Grb2-SH2 domain (IC 50 = 1.1-5.8 microM). More significantly, these (alpha-Me)Aa incorporated peptide inhibitors showed excellent activities in inhibiting the growth of erbB2-dependent MDA-MB-453 tumor cell lines with low micromolar IC 50 values, owing to the reduced peptidic nature and absence of pTyr or pTyr mimetics.

Identification of JWA as a novel functional gene responsive to environmental oxidative stress induced by benzo[a]pyrene and hydrogen peroxide.

Oxidative stress has been implicated as one of the primary mechanisms inducing DNA damage and believed to mediate aging and progression of numerous age-related diseases, including cancer. JWA, a gene previously described to mediate differentiation of leukemic cells, is also involved in cellular responses to environmental exposures linked to heat shock and chemical-mediated oxidative stresses. However, the precise pathways and mechanisms underlying these phenomena remain to be resolved. Our studies demonstrated that H(2)O(2) is the primary oxidative product responsible for benzo[a]pyrene (B[a]P)-induced JWA expression, and knockdown of JWA elevates H(2)O(2) (100 microM)- and B[a]P (100 microM)-induced DNA damage. In oxidative stress cell culture models, JWA was upregulated. JWA expression regulated a parallel rise in the base excision repair protein XRCC1 but a reduction in PARP1 in response to H(2)O(2)-induced DNA damage. Furthermore, we found that both H(2)O(2) and B[a]P exposure activated nuclear transcription factor I (NFI) in NIH-3T3 cells, which specifically bound to the CCAAT element in the JWA proximal promoter (-58/-28 bp) and thereby induced JWA expression. Consistently siRNA mediated a knockdown of NFI, which prevented JWA induction. These findings indicate that JWA may serve as a novel environmental stress sensor to protect cells against reactive oxygen species-associated DNA damage.

JWA as a functional molecule to regulate cancer cells migration via MAPK cascades and F-actin cytoskeleton.

Mitogen activated protein kinase (MAPK) cascades are thought to mediate diverse biological functions such as cell growth, differentiation and migration. Activated MAPK may affect microtubule (MT) which is essential for cellular polarity, differentiation and motility. Data in this study show that JWA, a newly identified novel microtubule-associated protein (MAP) was essential for the rearrangement of F-actin cytoskeleton and activation of MAPK cascades induced by arsenic trioxide (As2O3) and phorbol ester (PMA). Over-expression of JWA alone in HeLa, B16 and HCCLM3 cancer cells effectively inhibited cellular migration; whereas, cellular migration was significantly accelerated when cells were deficient in JWA expression. The mechanism underlying these phenomena might be due to JWA affected F-actin rearrangement. Furthermore, JWA deficiency blocked anti-migratory effect produced by As2O3 but enhanced the migratory effect initiated by PMA in HeLa cells. JWA SDR-SLR motifs are not only critical for the MAPK cascades activation, but also for cell migration. Further studies found that JWA differentially regulated cell migration via ERK downstream effectors focal adhesion kinase (FAK) and cyclooxygenase-2 (COX-2). Therefore, JWA regulated-tumor cellular migration might involve MAPK cascades activation and F-actin cytoskeleton rearrangement mechanisms. Our data provide an unexpected role for JWA in tumor cell migration behaviors.

JWA is required for the antiproliferative and pro-apoptotic effects of all-trans retinoic acid in Hela cells.

1. All-trans retinoic acid (ATRA) is known to inhibit cellular proliferation and induce differentiation and apoptosis. It usually activates gene expression by binding to a nuclear receptor that interacts with retinoic acid-response elements (RARE) and then activates the mitogen-activated protein kinase signal pathway. JWA, a newly identified ATRA-responsive gene, has recently been proposed as an important molecule for cellular differentiation induced by some chemicals, including ATRA. 2. To investigate the possible involvement of JWA in the inhibition of cellular proliferation and induction of apoptosis by ATRA, HeLa cells were stably transfected with sense or antisense JWA to establish cell lines that overexpressed or were deficient in JWA; ATRA (0.05-10 micromol/L) was used to induce cellular differentiation and apoptosis. 3. Western blot analysis revealed that ATRA caused increased expression of JWA in HeLa cells in a dose- and time-dependent manner, accompanied by activation of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. However, ERK1/2 phosphorylation induced by ATRA was inhibited in JWA-deficient HeLa cells. In JWA-overexpressing HeLa cells, ATRA showed more significant antiproliferative effects and induced more apoptosis. 4. The reporter gene assay showed that ATRA (5 mmol/L) enhanced the transcriptional activity of JWA by interacting with its promoter in the region from -194 to +107 bp (P < 0.01). Bioinformatic analysis indicated that the JWA promoter did not contain RARE, but did contain two CCAAT boxes in this fragment spanning -194 to +107 bp, which may be responsive to the ATRA-activated nuclear transcription factor CCAAT/enhancer binding proteins (C/EBP) or interacting proteins. Therefore, ATRA-inhibited cellular proliferation and -induced apoptosis in HeLa cells may be dependent on JWA transactivation via its C/EBP-binding motifs. 5. These data indicate that the inhibition of proliferation and the induction of apoptosis by ATRA are dependent on JWA expression in HeLa cells. The findings may represent a novel mechanism by which the effects of ATRA in regulating cellular proliferation and apoptosis are mediated, at least in part, by JWA expression.