RNF112-mediated FOXM1 ubiquitination suppresses the proliferation and invasion of gastric cancer.

Forkhead box M1 (FOXM1) plays a critical role in development physiologically and tumorigenesis pathologically. However, insufficient efforts have been dedicated to exploring the regulation, in particular the degradation of FOXM1. Here, the ON-TARGETplus siRNA library targeting E3 ligases was used to screen potential candidates to repress FOXM1. Of note, mechanism study revealed that RNF112 directly ubiquitinates FOXM1 in gastric cancer, resulting in a decreased FOXM1 transcriptional network and suppressing the proliferation and invasion of gastric cancer. Interestingly, the well-established small-molecule compound RCM-1 significantly enhanced the interaction between RNF112 and FOXM1, which further promoted FOXM1 ubiquitination and subsequently exerted promising anticancer effects in vitro and in vivo. Altogether, we demonstrate that RNF112 suppresses gastric cancer progression by ubiquitinating FOXM1 and highlight the RNF112/FOXM1 axis serves as both prognosis biomarker and therapeutic target in gastric cancer.

FOXM1 increases hTERT protein stability and indicates poor prognosis in gastric cancer.

Gastric cancer is one of most lethal diseases across the world. However, the underlying mechanism of gastric cancer carcinogenesis and development is still not fully known. Forkhead box M1 (FOXM1) belongs to the FOX family and has crucial roles in transactivation of multiple oncogenes in several cancer types, including gastric cancer. Recent studies have also shown the non-transcriptional function of FOXM1 via protein-protein interactions. Human telomerase reverse transcriptase (hTERT) is the core subunit of telomerase that facilitates cancer initiation and progression by maintaining cell immortalization, promoting cell proliferation and inhibiting cell apoptosis. However, the relationship between FOXM1 and hTERT in gastric cancer is still unclear. In our study, we found that FOXM1 and hTERT were convergent to the cell cycle-related pathways and they were positively related with advanced gastric cancer stages and poor outcomes. Simultaneous high levels of FOXM1 and hTERT predicted the worst prognosis. FOXM1 could increase hTERT protein rather than mRNA levels in a non-transcriptional manner. Mechanistically, FOXM1 interrupted the interaction between the E3 ligase MKRN1 and hTERT and decreased hTERT protein degradation. Further studies revealed that FOXM1 interacted with hTERT through its DNA-binding domain (DBD) region. Finally, we found that hTERT played important roles in FOXM1-mediated activation of the Wnt/ß-catenin pathway to promote gastric cancer cell proliferation. Taken together, we found a novel non-classical function of FOXM1 to increase hTERT protein stability. Targeting the FOXM1-hTERT pathway may be a potential therapeutic strategy in treating gastric cancer.

Realization of Oriented and Nanoporous Bismuth Chalcogenide Layers via Topochemical Heteroepitaxy for Flexible Gas Sensors.

Most van der Waals two-dimensional (2D) materials without surface dangling bonds show limited surface activities except for their edge sites. Ultrathin Bi2Se3, a topological insulator that behaves metal-like under ambient conditions, has been overlooked on its surface activities. Herein, through a topochemical conversion process, ultrathin nanoporous Bi2Se3 layers were epitaxially deposited on BiOCl nanosheets with strong electronic coupling, leading to hybrid electronic states with further bandgap narrowing. Such oriented nanoporous Bi2Se3 layers possessed largely exposed active edge sites, along with improved surface roughness and film forming ability even on inkjet-printed flexible electrodes. Superior room-temperature NO2 sensing performance was achieved compared to other 2D materials under bent conditions. Our work demonstrates that creating nanoscale features in 2D materials through topochemical heteroepitaxy is promising to achieve both favorable electronic properties and surface activity toward practical applications.

Helicobacter pylori infection induces stem cell-like properties in Correa cascade of gastric cancer.

Gastric cancer (GC) is the fourth leading cause of cancer-related death. Its poor prognosis is attributed to unclear pathogenesis. Currently, the most widely accepted model for elucidating the mechanism of GC is the Correa cascade, which covers several histological lesions of the gastric mucosa. GC stem cells (CSCs) are crucial for oncogenesis in the Correa cascade and GC progression. As Helicobacter pylori (H. pylori) is the etiological factor in the Correa cascade, growing evidence suggests that enhancement of gastric stem cell-like properties and increase in CSCs correlate with H. pylori infection. In this paper, we review recent studies that present pathogenic mechanisms by which H. pylori induces gastric stem cell-like properties and CSCs, which may supplement the existing Correa model of GC. First, the dysfunction of developmental signaling pathways associated with H. pylori infection leads to the enhancement of gastric stemness. Second, H. pylori infection promotes alteration of the gastric mucosal microenvironment. In addition, epithelial-mesenchymal transition (EMT) may contribute to H. pylori-induced gastric stemness. Taken together, understanding these pathogeneses will provide potential therapeutic targets for the treatment of CSCs and malignant GC in H. pylori induced-Correa cascade of GC.

Deficiency of microRNA-628-5p promotes the progression of gastric cancer by upregulating PIN1.

Gastric cancer is one of the most common cancer and is the second leading cause of cancer-related mortality in the world. PIN1, belonging to peptidyl-prolyl cis-trans isomerase family, uniquely catalyzes the structural transformation of phosphorylated Ser/Thr-Pro motif. It's high expressed in most cancers and promotes their progression. However, the mechanism of PIN1 high expression and its function in gastric cancer progression are still unclear. In this research, we revealed that PIN1 not only promotes the proliferation and colony formation of gastric cancer, but also increases its migration and invasion. The PIN1 expression in metastasis lesion is usually higher than the corresponding primary site. Inhibiting PIN1 by shRNA suppresses the progression of gastric cancer significantly. Besides, we demonstrated that miR-628-5p is a novel PIN1-targeted microRNA, and the expression of miR-628-5p is negatively correlated with PIN1 in gastric cancer. Exogenous expression of miR-628-5p inhibits the progression of gastric cancer that revered by restoring PIN1 expression. However, miR-628-5p is downregulated in majority of gastric cancer tissue especially in metastasis lesion. The lower miR-628-5p level indicates poorer prognosis. In summary, our study demonstrated that deficient miR-628-5p expression facilitates the expression of PIN1, and consequently promotes the progression of gastric cancer.

CircMRPS35 suppresses gastric cancer progression via recruiting KAT7 to govern histone modification.

BACKGROUND: Aberrant expression of circular RNAs contributes to the initiation and progression of cancers, but the underlying mechanism remains elusive. METHODS: RNA-seq and qRT-PCR were performed to screen differential expressed circRNAs between gastric cancer tissues and adjacent normal tissues. Candidate circRNA (circMRPS35) was screened out and validated by qRT-PCR. Cell proliferation and invasion ability were determined by CCK-8 and cell invasion assays. RNA-seq, GO-pathway, RNA pull-down and ChIRP were further applied to search for detailed mechanism. RESULTS: Here, a novel circRNA named circMRPS35, was screened out by RNA-seq in gastric cancer tissues, whose expression is related to clinicopathological characteristics and prognosis in gastric cancer patients. Biologically, circMRPS35 suppresses the proliferation and invasion of gastric cancer cells in vitro and in vivo. Mechanistically, circMRPS35 acts as a modular scaffold to recruit histone acetyltransferase KAT7 to the promoters of FOXO1 and FOXO3a genes, which elicits acetylation of H4K5 in their promoters. Particularly, circMRPS35 specifically binds to FOXO1/3a promoter regions directly. Thus, it dramatically activates the transcription of FOXO1/3a and triggers subsequent response of their downstream target genes expression, including p21, p27, Twist1 and E-cadherin, resulting in the inhibition of cell proliferation and invasion. Moreover, circMRPS35 expression positively correlates with that of FOXO1/3a in gastric cancer tissues. CONCLUSIONS: Our findings not only reveal the pivotal roles of circMRPS35 in governing histone modification in anticancer treatment, but also advocate for triggering circMRPS35/KAT7/FOXO1/3a pathway to combat gastric cancer.

Diverse regulatory manners of human telomerase reverse transcriptase.

Human telomerase reverse transcriptase (hTERT) is the core subunit of human telomerase and plays important roles in human cancers. Aberrant expression of hTERT is closely associated with tumorigenesis, cancer cell stemness maintaining, cell proliferation, apoptosis inhibition, senescence evasion and metastasis. The molecular basis of hTERT regulation is highly complicated and consists of various layers. A deep and full-scale comprehension of the regulatory mechanisms of hTERT is pivotal in understanding the pathogenesis and searching for therapeutic approaches. In this review, we summarize the recent advances regarding the diverse regulatory mechanisms of hTERT, including the transcriptional (promoter mutation, promoter region methylation and histone acetylation), post-transcriptional (mRNA alternative splicing and non-coding RNAs) and post-translational levels (phosphorylation and ubiquitination), which may provide novel perspectives for further translational diagnosis or therapeutic strategies targeting hTERT.

Loss of the Tumor Suppressor HACE1 Contributes to Cancer Progression.

HACE1 belongs to the family of HECT domain-containing E3 ligases, which plays an important role in the occurrence, invasion and metastatic process in many human malignancies. HACE1 is a tumor suppressor gene that is reduced in most cancer tissues compared to adjacent normal tissue. The loss or knocking out of HACE1 leads to enhanced tumor growth, invasion, and metastasis; in contrast, the overexpression of HACE1 can inhibit the development of tumors. Hypermethylation reduces the expression of HACE1, thereby promoting tumor development. HACE1 can inhibit the development of inflammation or tumors via the ubiquitination pathway. Therefore, HACE1 may be a potential therapeutic target, providing new strategies for disease prevention and treatment.

Regulation of the master regulator FOXM1 in cancer.

FOXM1 (forkhead box protein M1) is a critical proliferation-associated transcription factor that is widely spatiotemporally expressed during the cell cycle. It is closely involved with the processes of cell proliferation, self-renewal, and tumorigenesis. In most human cancers, FOXM1 is overexpressed, and this indicates a poor prognosis for cancer patients. FOXM1 maintains cancer hallmarks by regulating the expression of target genes at the transcriptional level. Due to its potential role as molecular target in cancer therapy, FOXM1 was named the Molecule of the Year in 2010. However, the mechanism of FOXM1 dysregulation remains indistinct. A comprehensive understanding of FOXM1 regulation will provide novel insight for cancer and other diseases in which FOXM1 plays a major role. Here, we summarize the transcriptional regulation, post-transcriptional regulation and post-translational modifications of FOXM1, which will provide extremely important implications for novel strategies targeting FOXM1.

Prolyl isomerase Pin1: a promoter of cancer and a target for therapy.

Pin1 is the only known peptidyl-prolyl cis-trans isomerase (PPIase) that specifically recognizes and isomerizes the phosphorylated Serine/Threonine-Proline (pSer/Thr-Pro) motif. The Pin1-mediated structural transformation posttranslationally regulates the biofunctions of multiple proteins. Pin1 is involved in many cellular processes, the aberrance of which lead to both degenerative and neoplastic diseases. Pin1 is highly expressed in the majority of cancers and its deficiency significantly suppresses cancer progression. According to the ground-breaking summaries by Hanahan D and Weinberg RA, the hallmarks of cancer comprise ten biological capabilities. Multiple researches illuminated that Pin1 contributes to these aberrant behaviors of cancer via promoting various cancer-driving pathways. This review summarized the detailed mechanisms of Pin1 in different cancer capabilities and certain Pin1-targeted small-molecule compounds that exhibit anticancer activities, expecting to facilitate anticancer therapies by targeting Pin1.

The PPARγ agonist rosiglitazone sensitizes the BH3 mimetic (-)-gossypol to induce apoptosis in cancer cells with high level of Bcl-2.

The BH3 mimetic (-)-gossypol (-)-G has shown promising efficacy to kill several kinds of cancer cells or potentiate current chemotherapeutics. But it induces limited apoptosis in cancer cells with high level of Bcl-2. The nuclear receptor PPARγ and its agonist rosiglitazone can suppress various malignancies. More importantly, rosiglitazone is able to enhance the anti-tumor effects of chemotherapy drugs such as carboplatin and tyrosine kinase inhibitors. In this study, we for the first time demonstrated that rosiglitazone could sensitize (-)-G to induce apoptosis in cancer cells with high level of Bcl-2. Furthermore, we found that (-)-G increased the mRNA level and protein stability of Mcl-1, which weakened the pro-apoptotic effect of (-)-G. Rosiglitazone attenuated the (-)-G-induced Mcl-1 stability through decreasing JNK phosphorylation. Additionally, rosiglitazone upregulated dual-specificity phosphatase 16 (DUSP16), leading to a reduction of (-)-G-triggered JNK phosphorylation. Animal experiments showed that rosiglitazone could sensitize (-)-G to repress the growth of cancer cells with high level of Bcl-2 in vivo. Taken together, our results suggest that the PPARγ agonists may enhance the therapeutic effect of BH3 mimetics in cancers with high level of Bcl-2 through regulating the DUSP16/JNK/Mcl-1 singling pathway. This study may provide novel insights into the cancer therapeutics based on the combination of PPARγ agonists and BH3 mimetics.

Efficient transformation of corn stover to furfural using p-hydroxybenzenesulfonic acid-formaldehyde resin solid acid.

In this work, p-hydroxybenzenesulfonic acid-formaldehyde resin acid catalyst (MSPFR), was synthesized by a hydrothermal method, and employed for the furfural production from raw corn stover. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, elemental analysis (EA), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the MSPFR. The effects of reaction time, temperature, solvents and corn stover loading were investigated. The MSPFR presented high catalytic activity for the formation of furfural from corn stover. When the MSPFR/corn stover mass loading ratio was 0.5, a higher furfural yield of 43.4% could be achieved at 190 °C in 100 min with 30.7% 5-hydroxymethylfurfural (HMF) yield. Additionally, quite importantly, the recyclability of the MSPFR for xylose dehydration is good, and for the conversion of corn stover was reasonable.

LncRNA LOC653786 promotes growth of RCC cells via upregulating FOXM1.

Renal cell carcinoma (RCC) is the most common kidney malignancy with poor prognosis. Recently, long noncoding RNAs (lncRNAs) have been demonstrated as important regulators in multiple cancers including RCC. LOC653786 is a lncRNA, but its role in cancer remains unclear. In this study, we for the first time found that LOC653786 was upregulated in RCC tissues and cell lines, and this lncRNA promoted growth and cell cycle progression of RCC cells. Moreover, we showed that LOC653786 elevated the expression of forkhead box M1 (FOXM1) and its downstream target genes cyclin D1 and cyclin B1 in RCC cells. Reporter assay revealed that LOC653786 enhanced the transcriptional activity of FOXM1 gene promoter. Additionally, knockdown of FOXM1 attenuated the LOC653786-enhanced growth and cell cycle progression of RCC cells. Meanwhile, silencing of LOC653786 suppressed RCC cell growth and cell cycle progression, which was alleviated by overexpression of FOXM1. The in vivo experiments in nude mice showed knockdown of LOC653786 repressed xenograft tumor growth and FOXM1 expression. In conclusion, our results demonstrate that LOC653786 accelerates growth and cell cycle progression of RCC cells via upregulating FOXM1, suggesting that the 'LOC653786/FOXM1' pathway may serve as a novel target for RCC treatment.

AKT-mediated phosphorylation of ATG4B impairs mitochondrial activity and enhances the Warburg effect in hepatocellular carcinoma cells.

Phosphorylation is a major type of post-translational modification, which can influence the cellular physiological function. ATG4B, a key macroautophagy/autophagy-related protein, has a potential effect on the survival of tumor cells. However, the role of ATG4B phosphorylation in cancers is still unknown. In this study, we identified a novel phosphorylation site at Ser34 of ATG4B induced by AKT in HCC cells. The phosphorylation of ATG4B at Ser34 had little effect on autophagic flux, but promoted the Warburg effect including the increase of L-lactate production and glucose consumption, and the decrease of oxygen consumption in HCC cells. The Ser34 phosphorylation of ATG4B also contributed to the impairment of mitochondrial activity including the inhibition of F1Fo-ATP synthase activity and the elevation of mitochondrial ROS in HCC cells. Moreover, the phosphorylation of ATG4B at Ser34 enhanced its mitochondrial location and the subsequent colocalization with F1Fo-ATP synthase in HCC cells. Furthermore, recombinant human ATG4B protein suppressed the activity of F1Fo-ATP synthase in MgATP submitochondrial particles from patient-derived HCC tissues in vitro. In brief, our results demonstrate for the first time that the phosphorylation of ATG4B at Ser34 participates in the metabolic reprogramming of HCC cells via repressing mitochondrial function, which possibly results from the Ser34 phosphorylation-induced mitochondrial enrichment of ATG4B and the subsequent inhibition of F1Fo-ATP synthase activity. Our findings reveal a noncanonical working pattern of ATG4B under pathological conditions, which may provide a scientific basis for developing novel strategies for HCC treatment by targeting ATG4B and its Ser34 phosphorylation.

Induction of SOCS3 by liver X receptor suppresses the proliferation of hepatocellular carcinoma cells.

Liver X receptor (LXR), a member of nuclear receptor superfamily, is involved in the regulation of glucose, lipid and cholesterol metabolism. Recently, it has been reported that LXR suppress different kinds of cancers including hepatocellular carcinoma (HCC). However, the corresponding mechanism is still not well elucidated. In the present study, we found that activation of LXR downregulated cyclin D1 while upregulated p21 and p27 by elevating the level of suppressor of cytokine signaling 3 (SOCS3), leading to the cell cycle arrest at G1/S phase and growth inhibition of HCC cells. Moreover, we demonstrated that LXRα (not LXRß) mediated the induction of SOCS3 in HCC cells. Subsequently, we showed that LXR activation enhanced the mRNA stability of SOCS3, but had no significant influence on the transcriptional activity of SOCS3 gene promoter. The experiments in nude mice revealed that LXR agonist inhibited the growth of xenograft tumors and enhanced SOCS3 expression in vivo. These results indicate that "LXRα-SOCS3-cyclin D1/p21/p27" is a novel pathway by which LXR exerts its anti-HCC effects, suggesting that the pathway may be a new potential therapeutic target for HCC treatment.

Inhibition of COX2 enhances the chemosensitivity of dichloroacetate in cervical cancer cells.

Dichloroacetate (DCA), a traditional mitochondria-targeting agent, has shown promising prospect as a sensitizer in fighting against malignancies including cervical cancer. But it is unclear about the effect of DCA alone on cervical tumor. Moreover, previous reports have demonstrated that the increased cyclooxygenase-2 (COX2) expression is associated with chemoresistance and poor prognosis of cervical cancer. However, it is still unknown whether COX2 can affect the sensitivity of DCA in cervical cancer cells. In this study, we found that cervical cancer cells were insensitive to DCA. Furthermore, we for the first time revealed that DCA could upregulate COX2 which impeded the chemosensitivity of DCA in cervical cancer cells. Mechanistic study showed that DCA reduced the level of RNA binding protein quaking (QKI), leading to the decay suppression of COX2 mRNA and the subsequent elevation of COX2 protein. Inhibition of COX2 using celecoxib could sensitize DCA in repressing the growth of cervical cancer cells both in vitro and in vivo. These results indicate that COX2 is a novel resistance factor of DCA, and combination of celecoxib with DCA may be beneficial to the treatment of cervical cancer.

HSF1 upregulates ATG4B expression and enhances epirubicin-induced protective autophagy in hepatocellular carcinoma cells.

Considerable evidences have shown that both heat shock transcription factor 1 (HSF1) and autophagy can attenuate the sensitivity of hepatocellular carcinoma (HCC) cells to chemotherapeutic reagents. However, it is still little known whether HSF1 is associated with autophagy in regulating the chemosensitivity of HCC cells. In this study, we for the first time demonstrated that HSF1 markedly attenuated the killing effect of epirubicin (EPI) to HCC cells via enhancing the EPI-induced protective autophagy. Mechanistically, HSF1 upregulated autophagy related 4B (ATG4B) in HCC cells, which enhanced the EPI-triggered protective autophagy. Reporter assay showed that HSF1 increased the transcriptional activity of ATG4B gene promoter, and chromatin immunoprecipitation assay verified that HSF1 bound to the site (-1429 to -1417) in ATG4B gene promoter region. The experiments in nude mice showed that knockdown of HSF1 or ATG4B strengthened the anti-HCC effect of EPI in vivo. Collectively, these results revealed that HSF1 elevates ATG4B via promoting its transcription, which alleviates the sensitivity of EPI in HCC cells through enhancing protective autophagy, suggesting that the "HSF1/ATG4B/protective autophagy" pathway may be a novel target for developing sensitizing strategy to HCC chemotherapy.

Metformin Synergizes with BCL-XL/BCL-2 Inhibitor ABT-263 to Induce Apoptosis Specifically in p53-Defective Cancer Cells.

p53 deficiency, a frequent event in multiple kinds of malignancies, decreases the sensitivity of diverse targeted chemotherapeutics including the BCL-XL/BCL-2 inhibitor ABT-263. Loss of p53 function can activate mTOR complex 1 (mTORC1), which may make it a vulnerable target. Metformin has shown anti-neoplastic efficiency partially through suppressing mTORC1. However, it remains unknown whether mTORC1 activation confers ABT-263 resistance and whether metformin can overcome it in the p53-defective contexts. In this study, we for the first time demonstrated that metformin and ABT-263 synergistically elicited remarkable apoptosis through orchestrating the proapoptotic machineries in various p53-defective cancer cells. Mechanistic studies revealed that metformin sensitized ABT-263 via attenuating mTORC1-mediated cap-dependent translation of MCL-1 and survivin and weakening internal ribosome entry site (IRES)-dependent translation of XIAP Meanwhile, ABT-263 sensitized metformin through disrupting the BCL-XL/BIM complex. However, metformin and ABT-263 had no synergistic killing effect in p53 wild-type (p53-WT) cancer cells because the cotreatment dramatically induced the senescence-associated secretory phenotype (SASP) in the presence of wild type p53, and SASP could aberrantly activate the AKT/ERK-mTORC1-4EBP1-MCL-1/survivin signaling axis. Blocking the axis using corresponding kinase inhibitors or neutralizing antibodies against different SASP components sensitized the cotreatment effect of metformin and ABT-263 in p53-WT cancer cells. The in vivo experiments showed that metformin and ABT-263 synergistically inhibited the growth of p53-defective (but not p53-WT) cancer cells in tumor xenograft nude mice. These results suggest that the combination of metformin and ABT-263 may be a novel targeted therapeutic strategy for p53-defective cancers. Mol Cancer Ther; 16(9); 1806-18. ©2017 AACR.

Dichloroacetate and metformin synergistically suppress the growth of ovarian cancer cells.

Both dichloroacetate (DCA) and metformin (Met) have shown promising antitumor efficacy by regulating cancer cell metabolism. However, the DCA-mediated protective autophagy and Met-induced lactate accumulation limit their tumor-killing potential respectively. So overcoming the corresponding shortages will improve their therapeutic effects. In the present study, we found that DCA and Met synergistically inhibited the growth and enhanced the apoptosis of ovarian cancer cells. Interestingly, we for the first time revealed that Met sensitized DCA via dramatically attenuating DCA-induced Mcl-1 protein and protective autophagy, while DCA sensitized Met through markedly alleviating Met-induced excessive lactate accumulation and glucose consumption. The in vivo experiments in nude mice also showed that DCA and Met synergistically suppressed the growth of xenograft ovarian tumors. These results may pave a way for developing novel strategies for the treatment of ovarian cancer based on the combined use of DCA and Met.