Chenfei Hu

miR‐106a is frequently upregulated in gastric cancer and inhibits the extrinsic apoptotic pathway by targeting FAS

Emerging evidence has shown the association of aberrantly expressed miR‐106a with cancer development, however, little is known about its potential role in gastric carcinogenesis. In our present study, obviously overexpressed miR‐106a was found in gastric cancer tissues compared with their nontumor counterparts. Suppression of miR‐106a significantly inhibited gastric cancer cell proliferation and triggered apoptosis. Bioinformatic analysis combining with validation experiments identified FAS as a direct target of miR‐106a. Rescue experiments and examination of caspase‐8, PARP and caspase‐3 further approved that miR‐106a could inhibit gastric cancer cell apoptosis through interfering with FAS‐mediated apoptotic pathway. Moreover, a significant inverse correlation was found between miR‐106a and FAS expression not only in gastric cancer cell lines but also in gastric cancer specimens. Taken together, these findings suggest that ectopicly overexpressed miR‐106a may play an oncogenic role in gastric carcinogenesis and impair extrinsic apoptotic pathway through targeting FAS.

Upregulation of KLF4 by methylseleninic acid in human esophageal squamous cell carcinoma cells: Modification of histone H3 acetylation through HAT/HDAC interplay.

Esophageal squamous cell carcinoma (ESCC) occurs at a very high frequency in certain areas of China. Supplementation with selenium‐containing compounds was associated with a significantly lower cancer mortality rate in a study conducted in Linxia, China. Thus, selenium could be a potential anti‐esophageal cancer agent. In this study, methylseleninic acid (MSA) could inhibit cell growth of ESCC cells in vitro and in vivo. Upon treated with MSA, the activity of histone deacetylases (HDACs) was decreased and general control nonrepressed protein 5 (GCN5) was upregulated in ESCC cells. Meanwhile, a significant increase of H3K9 acetylation (H3K9ac) was detected. Upregulation of Krüppel‐like factor 4 (KLF4) was also observed after MSA treatment. Additionally, the acetylated histone H3 located more at KLF4 promoter region after MSA treatment, shown by chromatin immunoprecipitation (ChIP) assay. Moreover, knockdown of GCN5 decreased the protein level of both H3K9ac and KLF4, along with less cell growth inhibition. Taken all, our results indicated that MSA could inhibit ESCC cell growth, at least in part, by MSA‐HDAC/GCN5‐H3K9ac‐KLF4 axis. To our best knowledge, this is the first report that MSA induced acetylation of histone H3 at Lys9, which might depend on the activities and the balance between HDACs and HATs.

Overexpression of the DEC1 protein induces senescence in vitro and is related to better survival in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a leading cause of cancer-related death in China and has limited effective therapeutic options except for early surgery, since the underlying molecular mechanism driving its precursor lesions towards invasive ESCC is not fully understood. Cellular senescence is the state of the permanent growth arrest of a cell, and is considered as the initial barrier of tumor development. Human differentiated embryo chondrocyte expressed gene 1 (Dec1) is an important transcription factor that related to senescence. In this study, DEC1 immunohistochemical analysis was performed on tissue microarray blocks constructed from ESCC combined with adjacent precursor tissues of 241 patients. Compared with normal epithelia, DEC1 expression was significantly increased in intraepithelial neoplasia and DEC1 expression was significantly decreased in ESCC in comparison with intraepithelial neoplasia. In vitro, DEC1 overexpression induced cellular senescence, and it inhibited cell growth and colony formation in ESCC cell line EC9706. Fresh esophagectomy tissue sections from five ESCC patients were detected by immunohistochemistry of DEC1 and senescence-associated β-galactosidase (SA-β-Gal) activity, and strongly positive expression of DEC1 was correlated to more senescent cells in these fresh tissue sections. Kaplan – Meier method analysis of the 241 patients revealed that DEC1 expression levels were significantly correlated with the survival of ESCC patients after surgery. The expression levels of DEC1 were also correlated with age, tumor embolus, depth of invasion of ESCC, lymph metastasis status and pTNMs. These results suggest that DEC1 overexpression in precursor lesions of ESCC is a protective mechanism by inducing cellular senescence in ESCC initiation, and DEC1 may be a potential prognostic marker of ESCC.

Methylseleninic acid activates Keap1/Nrf2 pathway via up-regulating miR-200a in human oesophageal squamous cell carcinoma cells.

Methylseleninic acid (MSA), as a potent second-generation selenium compound, could activate KLF4/miR-200a/Keap1/Nrf2 pathway in oesophageal squamous cell carcinoma cells.

P21-Activated Kinase 7 Mediates Cisplatin-Resistance of Esophageal Squamous Carcinoma Cells with Aurora-A Overexpression

Aurora-A overexpression is common in various types of cancers and has been shown to be involved in tumorigenesis through different signaling pathways, yet how the deregulation affects cancer therapeutics remains elusive. Here we showed that overexpression of Aurora-A rendered esophageal cancer cells resistance to cisplatin (CDDP) by inhibiting apoptosis. By using an apoptosis array, we identified a downstream gene, p21-activated kinase 7 (PAK7). PAK7 was upregulated by Aurora-A overexpression at both mRNA and protein levels. Importantly, the expression levels of Aurora-A and PAK7 were correlated in ESCC primary samples. Chromatin immunoprecipitation (ChIP) assay revealed that binding of E2F1 to the promoter of PAK7 was significantly enhanced upon Aurora-A activation, and knockdown of transcription factor E2F1 decreased PAK7 expression, suggesting that Aurora-A regulated PAK7 through E2F1. Furthermore, we demonstrated that PAK7 knockdown led to increased apoptosis, and Aurora-A-induced resistance to CDDP was reversed by downregulation of PAK7, suggesting PAK7 was a downstream player of Aurora-A that mediated chemoresistance of ESCC cells to CDDP. Our data suggest that PAK7 may serve as an attractive candidate for therapeutics in ESCC patients with Aurora-A abnormality.

IL-6 influences the polarization of macrophages and the formation and growth of colorectal tumor

Macrophages play a crucial role in tumorigenesis depending upon the phenotype of macrophages found in tumor microenvironments. To date, how the tumor microenvironment affects the phenotypes of macrophages is not yet fully understood. In this study, we constructed a NIH3T3/Src cell line stably overexpresses the Src protein and found that conditioned medium from this cell line was able to induce polarization towards the M2 phenotype in primary bone marrow-derived macrophages (BMDM) and Ana-1 macrophages. Further investigation revealed that IL-6 produced by NIH3T3/Src cells plays a key role in M2 polarization. During the development of colorectal cancer in C57BL/6J-ApcMin/+ mice, increased IL-6 secretion in the interstitial fluid of the colorectal tissues was observed. Furthermore, tumorigenesis in IL-6tm1Kopf mice treated with AOM-DSS, an IL-6 knockout mouse strain, was significantly inhibited compared with the control group, suggesting the important role of IL-6 in promoting tumorigenicity. Our findings identify the target molecules and proinflammatory cytokines responsible for promoting polarization towards the M2 phenotype in macrophages present in tumor microenvironment, which may be useful for the design of novel therapeutic strategies for colorectal cancer.

Overexpression of KLF4 promotes cell senescence through microRNA-203-survivin-p21 pathway

Krüppel-like factor 4 (KLF4) is a transcription factor and functions as a tumor suppressor or tumor promoter in different cancer types. KLF4 regulates many gene expression, thus affects the process of cell proliferation, differentiation, and apoptosis. Recently, KLF4 was reported to induce senescence during the generation of induced pluripotent stem (iPS) cells, but the exact mechanism is still unclear. In this study, we constructed two doxycycline-inducing KLF4 cell models, and demonstrated overexpression of KLF4 could promote cell senescence, detected by senescence-associated β-galactosidase activity assay. Then we confirmed that p21, a key effector of senescence, was directly induced by KLF4. KLF4 could also inhibit survivin, which could indirectly induce p21. By miRNA microarray, we found a series of miRNAs regulated by KLF4 and involved in senescence. We demonstrated that KLF4 could upregulate miR-203, and miR-203 contributed to senescence through miR-203-survivin-p21 pathway. Our results suggest that KLF4 could promote cell senescence through a complex network: miR-203, survivin, and p21, which were all regulated by overexpression of KLF4 and contributed to cell senescence.

Abstract 1550: Supernatant of NIH3T3/Src(Y527F) cell line induced Ana-1 macrophages to tumor-associated macrophages by IL-6.

Macrophages (Mф) is the major components of the solid tumors. Tumor-associated macrophages (TAM) play an important role in the development of tumor inflammation. The tumor microenvironment could induce macrophages differentiation into TAM, and the TAM could regulate tumor growth and invasion. However, the mechanisms that by which signaling pathways contribute to cell differentiation are not well defined. As we known, the tumor microenvironment in vivo is complex and integrated by a variety of cells and factors. In this study, we chose NIH3T3 cell line to construct a stable Src(Y527F) expression system. We found that its supernatant could induce macrophages differentiation into TAM in vitro. When we injected the cell mixture of Ana-1 macrophages and NIH3T3/Src(Y527F) cells into nude mice, the volume of tumors increased more quickly than the control group that just injected NIH3T3/Src(Y527F) cells only. And, we also found that the tumors became more invasive than control tumors. Furthermore, 62 cytokines were tested by using Cytokine Antibody Array, the result showed that 13 of them significantly changed in the supernatant of NIH3T3/Src(Y527F) cells compared with NIH3T3. Strikingly, IL-6 was 71-fold up-regulated. When we added IL-6 in the supernatant, it could also induce Ana-1 macrophages differentiation into a TAM phenotype. Our findings indicated that IL-6 might play an important role in the differentiation of Ana-1 from macrophages to TAM by using the supernatant of NIH3T3/Src(Y527F) cell line. Citation Format: Lechuang Chen, Chenfei Hu, Qing Xu, Kai Ma, Mei Liu, Hongxia Zhu, Ningzhi Xu. Supernatant of NIH3T3/Src(Y527F) cell line induced Ana-1 macrophages to tumor-associated macrophages by IL-6. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1550. doi:10.1158/1538-7445.AM2013-1550

Abstract A19: miR-19a modulates chemoradiotherapy resistance in human cervical cancer

Cervical cancer is one of the most common cancers in women worldwide. Advanced uterine cervical squamous cell carcinomasuterine (UCSCC) patients in FIGO stage IIb or IIIb treated with platinum based concomitant chemoradiotherapy. However, clinical outcomes vary significantly and are difficult to predict. Tumor intrinsic chemoradiotherapy sensitivity is one of the crucial reasons for concomitant chemoradiotherapy failure in UCSCC. In this study, we identified the relationship between miR-19a and sensitivity to concomitant chemoradiotherapy. The UCSCC patients in FIGO stage IIb or IIIb treated with platinum based concurrent chemoradiotherapy at the Cancer Institute and Hospital, Chinese Academy of Medical Sciences. Patients with progressive disease during first line platinum based chemotherapy or those who suffered recurrent disease within 6 months of completing first line therapy were termed resistant. Patients without recurrence or with recurrences beyond 6 months were termed sensitive. We examined the expression level of miR-19a in 30 cervix biopsies samples, including 10 resistant and 20 sensitive samples. We found miR-19a was significantly up-regulated in resistant group compared with sensitive group (p <0.05). Our study indicated that miR-19a might be a marker to identify cervical cancer patients who are likely to fail concomitant chemoradiotherapy. To verify role of miR-19ain cervical cancer cells is worthy of further investigation. Citation Format: Mei Liu, Lingying Wu, Ningzhi Xu, Jusheng An, Jinlong Hu, Manni Huang, Binbin Tu, Chenfei Hu, Zaozao Wang, Hongxia Zhu. miR-19a modulates chemoradiotherapy resistance in human cervical cancer. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A19.