Longbang Chen

MicroRNA-200b reverses chemoresistance of docetaxel-resistant human lung adenocarcinoma cells by targeting E2F3

MicroRNAs (miRNAs) have been identified as important posttranscriptional regulators involved in various biological and pathological processes of cells, but their association with tumor chemoresistance has not been fully understood.

Progress and Prospects of Long Noncoding RNAs (lncRNAs) in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequently occurring cancers with poor prognosis, and novel diagnostic or prognostic biomarkers and therapeutic targets for HCC are urgently required. With the advance of high-resolution microarrays and massively parallel sequencing technology, lncRNAs are suggested to play critical roles in the tumorigenesis and development of human HCC. To date, dysregulation of many HCC-related lncRNAs such as HULC, HOTAIR, MALAT1, and H19 have been identified. From transcriptional “noise” to indispensable elements, lncRNAs may re-write the central dogma. Also, lncRNAs found in body fluids have demonstrated their utility as fluid-based noninvasive markers for clinical use and as therapeutic targets for HCC. Even though several lncRNAs have been characterized, the underlying mechanisms of their contribution to HCC remain unknown, and many important questions about lncRNAs need resolving. A better understanding of the molecular mechanism in HCC-related lncRNAs will provide a rationale for novel effective lncRNA-based targeted therapies. In this review, we highlight the emerging roles of lncRNAs in HCC, and discuss their potential clinical applications as biomarkers for the diagnosis, prognosis, monitoring and treatment of HCC.

MiR-100 resensitizes docetaxel-resistant human lung adenocarcinoma cells (SPC-A1) to docetaxel by targeting Plk1

MicroRNAs (miRNAs) expression correlates with biological characteristics of both normal cells and cancer cells, but their roles in cancer chemoresistance remain unclear. By microarray analysis, miR-100 was found significantly down-regulated in docetaxel-resistant SPC-A1/DTX cells compared with parental SPC-A1 cells. Ectopic miR-100 expression resensitized SPC-A1/DTX cells to docetaxel by suppression of cell proliferation and induction of cell arrest in G(2)/M phase and apoptosis. Knock-down of Plk1, which was a direct target of miR-100, yielded similar effects as that of ectopic miR-100 expression. The inverse correlation between miR-100 and Plk1 expression was also detected in nude mice SPC-A1/DTX tumor xenografts and clinical lung adenocarcinoma tissues and was proved to be related with the in vivo response to docetaxel. Thus, our results suggested that down-regulation of miR-100 could lead to Plk1 over-expression and eventually to docetaxel chemoresistance of human lung adenocarcinoma.

Inhibition of ZEB1 reverses EMT and chemoresistance in docetaxel-resistant human lung adenocarcinoma cell line

Docetaxel has been used as one of the first‐line chemotherapies in solid tumors including advanced non‐small cell lung cancer (NSCLC). However, limited responses to chemotherapy are observed in clinic and the molecular mechanisms have not been fully understood. Emerging evidence suggests that epithelial–mesenchymal transition (EMT) plays an important role in the processes of tumor metastasis as well as resistance towards anticancer agents. In this study, it was observed that docetaxel‐resistant human lung adenocarcinoma cell line (SPC‐A1/DTX) was typical of mesenchymal phenotype. SPC‐A1/DTX cell line has increased migratory and invasive capacity both in vitro and in vivo. Among the master EMT‐inducing transcriptional factors, ZEB1 was found to be significantly increased in SPC‐A1/DTX cell line. ZEB1 knockdown with RNA interference could reverse the EMT phenotype and inhibit the migratory ability of SPC‐A1/DTX cells. Furthermore, inhibition of ZEB1 significantly enhanced the chemosensitivity of SPC‐A1/DTX cells to docetaxel in vitro and in vivo and ectopic expression of ZEB1 increased the chemoresistance of SPC‐A1 cells to docetaxel. All these results provide experimental evidence that ZEB1 might be an attractive target for the treatment of human NSCLC. J. Cell. Biochem. 114: 1395–1403, 2013.

FOXM1 expression correlates with tumor invasion and a poor prognosis of colorectal cancer.

FOXM1, a member of the Forkhead Box (Fox) family of transcription factors, plays a critical role in tumor development and metastasis. The aim of this study was to elucidate its role in colorectal cancer (CRC), particularly prognosis and metastasis. Semi-quantitative RT-PCR and Western blot assays were used to measure the expression levels of FOXM1 mRNA and protein in 15 CRC and adjacent normal mucosa tissues. Immunohistochemical assay was performed to detect FOXM1 protein expression in 112 CRC tissues and further determine its clinicopathological and prognostic significance. RNA interference (RNAi) was used to knockdown endogenous FOXM1 expression in CRC cell lines and to analyze the effects of FOXM1 knockdown on migration and invasion of CRC cells. The relative expression levels of FOXM1 mRNA and protein were significantly higher in CRC tissues than in adjacent normal mucosa tissues (P<0.01). In addition, the immunostaining of FOXM1 protein was stronger in CRC tissues than in adjacent normal mucosa tissues. By statistical analysis, we showed that high FOXM1 expression was closely correlated with the presence of lymph node metastasis, incidence of liver metastasis, and advanced TNM stage. Moreover, the cumulative 5-year survival rate of CRC patients with high FOXM1 expression was lower than that of those with low FOXM1 expression (P=0.0047). Multivariate analysis showed that the status of FOXM1 expression was an independent prognostic factor for CRC patients (P=0.025). Furthermore, RNAi-mediated FOXM1 knockdown could significantly inhibit growth, migration and invasion of CRC cells. Our results showed that FOXM1 over-expression is a molecular marker predicting increased invasive/metastatic potential of CRC and a poorer prognosis.

HMGB1-mediated autophagy promotes docetaxel resistance in human lung adenocarcinoma

BackgroundDocetaxel resistance remains a major obstacle in the treatment of non-small cell lung cancer (NSCLC). High-mobility group box 1 (HMGB1) has been shown to promote autophagy protection in response to antitumor therapy, but the exact molecular mechanism underlying HMGB1-mediated autophagy has not been clearly defined.MethodsLung adenocarcinoma (LAD) cells were transfected with pcDNA3.1-HMGB1 or HMGB1 shRNA, followed by docetaxel treatment. Cell viability and proliferation were tested by MTT assay and colony formation assay, respectively. Annexin V flow cytometric analysis and western blot analysis of activated caspase3 and cleaved PARP were used to evaluate apoptosis, while immunofluorescence microscopy and transmission electron microscopy were applied to assess autophagy activity. The formation of the Beclin-1-PI3K-III complex was examined by immunoprecipitation analysis. NOD/SCID mice were inoculated with docetaxel-resistant SPC-A1/DTX cells transfected with control or HMGB1 shRNA.ResultsHMGB1 translocated from the nucleus to the cytoplasm in LAD cells exposed to docetaxel and acted as a positive regulator of autophagy, which inhibited apoptosis and increased drug resistance. Suppression of HMGB1 restored the sensitivity of LAD cells to docetaxel both in vivo and in vitro. Mechanistic investigation revealed that HMGB1 promoted the formation of the Beclin-1-PI3K-III complex through activating the mitogen-activated protein kinase (MEK)-extracellular signal-regulated kinase (ERK) signaling pathway, thereby regulating autophagosome formation.ConclusionsOur results demonstrated that HMGB1-regulated autophagy is a significant contributor to docetaxel resistance in LAD cells. Suppression of HMGB1 or limiting HMGB1 cytosolic translocation diminished autophagic protection in response to docetaxel in LAD cells.

MicroRNA-149 Suppresses Colorectal Cancer Cell Migration and Invasion by Directly Targeting Forkhead Box Transcription Factor FOXM1

Background/Aims: The aim of this study is to investigate the clinicopathological and prognostic values of miR-149 expression and its roles in colorectal cancer (CRC) progression. Methods: qRT-PCR was performed to detect miR-149 expression in CRC cell lines or tissues. Also, the clinical significance of miR-149 expression was investigated. The study further explored whether miR-149 inhibits migration and invasion of CRC cells by targeting the mammalian Forkhead Box M1 (FOXM1). Results: miR-149 was significantly downregulated in CRC tissues, and low miR-149 expression was observed to be significantly correlated with lymph node or distant metastasis and advanced TNM stage of CRC patients. Patients with low miR-149 expression showed poorer prognosis than those with high miR-149 expression, and multivariate analyses indicated that status of miR-149 expression might be an independent prognostic factor. Gain- and loss - of - function assays indicated that miR-149 significantly inhibited growth, migration and invasion of CRC cells by targeting FOXM1. Furthermore, FOXM1 was significantly uiregulated in CRC tissues and inversely correlated with miR-149 expression. Conclusions: mR-149 was an independent prognostic factor and could inhibit migration and invasion of CRC cells, at least partially by targeting FOXM1.

MicroRNA-145: a potent tumour suppressor that regulates multiple cellular pathways.

MicroRNAs are endogenous, small (18–25 nucleotides) non‐coding RNAs, which regulate genes expression by directly binding to the 3′‐untranslated regions of the target messenger RNAs. Emerging evidence shows that alteration of microRNAs is involved in cancer development. MicroRNA‐145 is commonly down‐regulated in many types of cancer, regulating various cellular processes, such as the cell cycle, proliferation, apoptosis and invasion, by targeting multiple oncogenes. This review aims to summarize the recent published literature on the role of microRNA‐145 in regulating tumourigenesis and progression, and explore its potential for cancer diagnosis, prognosis and treatment.

The Emerging Roles of Long Noncoding RNA ROR (lincRNA-ROR) and its Possible Mechanisms in Human Cancers

To date, there is only up to 2% of protein-coding genes that are stably transcribed, whereas the vast majority are non-coding RNAs (ncRNAs). These ncRNAs, also known as non-messenger RNAs (nmRNAs) or functional RNAs (fRNAs), include transfer RNAs, ribosomal RNAs, microRNAs and long non-coding RNAs (lncRNAs). With the advance of high-resolution microarrays and massively parallel sequencing technology, lncRNAs have gained extended attentions nowadays and are found to play important roles in tumorigenesis and progression of human cancers. Long intergenic non-protein coding RNA, regulator of reprogramming (linc-ROR), was first discovered in induced pluripotent stem cells (iPSCs), where it was controlled by the key pluripotency factors Oct4, Sox2 and Nanog. Linc-ROR has been shown to be dysregulated in many types of cancers, including breast cancer (BC), pancreatic cancer (PC), hepatocellular cancer (HCC), endometrial cancer (EC), and nasopharyngeal carcinoma (NPC). Also, linc-ROR functions as regulatory molecule in a large amount of biological processes. However, the underlying mechanisms of its contribution to carcinogenesis remain to be elucidated. In this review, we will emphasize on the characteristics of linc-ROR and their roles in different types of human cancers.

Let-7c Governs the Acquisition of Chemo- or Radioresistance and Epithelial-to-Mesenchymal Transition Phenotypes in Docetaxel-Resistant Lung Adenocarcinoma

MicroRNA (miRNA) expression and functions have been reported to contribute to phenotypic features of tumor cells. Although targets and functional roles for many miRNAs have been described in lung adenocarcinoma (LAD), their pathophysiologic roles in phenotypes of chemoresistant LAD cells are still largely unclear. Previously, docetaxel (DTX)-resistant LAD cell lines (SPC-A1/DTX and H1299/DTX) were established by our laboratory and displayed chemo- or radioresistance and mesenchymal features with enhanced invasiveness and motility. Unbiased miRNA profiling indicated that let-7c (MIRLET7C) was significantly downregulated in SPC-A1/DTX cells. Ectopic let-7c expression increased the in vitro and in vivo chemo- or radiosensitivity of DTX-resistant LAD cells through enhanced apoptosis, reversal of epithelial-to-mesenchymal phenotypes, and inhibition of in vivo metastatic potential via inactivation of Akt phosphorylation, whereas a let-7c inhibitor decreased the chemo- or radiosensitivity of parental cells. Further investigation suggested that let-7c significantly reduced the luciferase activity of a Bcl-xL 3′-UTR-based reporter, concordant with reduced Bcl-xL protein levels. Additionally, siRNA-mediated Bcl-xL knockdown mimicked the same effects of let-7c precursor, and enforced Bcl-xL expression partially rescued the effects of let-7c precursor in DTX-resistant LAD cells. Furthermore, we found that Bcl-xL was significantly upregulated in DTX-nonresponding LAD tissues, and its expression was inversely correlated with let-7c expression. This study suggests an important role for let-7c in the molecular etiology of chemoresistant lung adenocarcinoma. Mol Cancer Res; 11(7); 699–713. ©2013 AACR.