The epithelial-to-mesenchymal transition (EMT), a process involving the breakdown of cell-cell junctions and loss of epithelial polarity, is closely related to cancer development and metastatic progression. While the cystic fibrosis transmembrane conductance regulator (CFTR), a Cl(-) and HCO3(-) conducting anion channel expressed in a wide variety of epithelial cells, has been implicated in the regulation of epithelial polarity, the exact role of CFTR in the pathogenesis of cancer and its possible involvement in EMT process have not been elucidated. Here we report that interfering with CFTR function either by its specific inhibitor or lentiviral miRNA-mediated knockdown mimics TGF-β1-induced EMT and enhances cell migration and invasion in MCF-7. Ectopic overexpression of CFTR in a highly metastatic MDA-231 breast cancer cell line downregulates EMT markers and suppresses cell invasion and migration in vitro, as well as metastasis in vivo. The EMT-suppressing effect of CFTR is found to be associated with its ability to inhibit NFκB targeting urokinase-type plasminogen activator (uPA), known to be involved in the regulation of EMT. More importantly, CFTR expression is found significantly downregulated in primary human breast cancer samples, and is closely associated with poor prognosis in different cohorts of breast cancer patients. Taken together, the present study has demonstrated a previously undefined role of CFTR as an EMT suppressor and its potential as a prognostic indicator in breast cancer.

Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) is expressed in the epithelial cells of a wide range of organs/tissues from which most cancers are derived. Although accumulating reports have indicated the association of cancer incidence with genetic variations in CFTR gene, the exact role of CFTR in cancer development and the possible underlying mechanism have not been elucidated. Here, we report that CFTR expression is significantly decreased in both prostate cancer cell lines and human prostate cancer tissue samples. Overexpression of CFTR in prostate cancer cell lines suppresses tumor progression (cell growth, adhesion and migration), whereas knockdown of CFTR leads to enhanced malignancies both in vitro and in vivo. In addition, we demonstrate that CFTR knockdown-enhanced cell proliferation, cell invasion and migration are significantly reversed by antibodies against either urokinase plasminogen activator (uPA) or uPA receptor (uPAR), which are known to be involved in various malignant traits of cancer development. More interestingly, overexpression of CFTR suppresses uPA by upregulating the recently described tumor suppressor microRNA-193b (miR-193b), and overexpression of pre-miR-193b significantly reverses CFTR knockdown-enhanced malignant phenotype and abrogates elevated uPA activity in prostate cancer cell line. Finally, we show that CFTR gene transfer results in significant tumor repression in prostate cancer xenografts in vivo. Taken together, the present study has demonstrated a previously undefined tumor-suppressing role of CFTR and its involvement in regulation of miR-193b in prostate cancer development.

Objectives: Emerging evidences indicated the importance of long non-coding RNAs (lncRNAs) in the tumorigenesis and deterioration of malignant tumours. To our knowledge, the study about lncRNAs in papillary thyroid carcinoma (PTC) is still inadequate. ABHD11-AS1 was highly expressed in the PTC samples of The Cancer Genome Atlas database. This study focused on the biological function and mechanism of lncRNA ABHD11-AS1 in PTC. Materials and methods: qRT-PCR analysis was used to examine the expression of ABHD11-AS1 in PTC tissues and cell lines. The prognostic significance of ABHD11-AS1 for the patients with PTC was analysed with Kaplan-Meier analysis. The effects of ABHD11-AS1 knockdown on the cell proliferation and metastasis were evaluated by in vitro functional assays and in vivo experiments. The molecular mechanism which contributed to the oncogenic role of ABHD11-AS1 in PTC was explored by conducting mechanism experiments. Rescue assays were carried out for final demonstration. Results: High expression of ABHD11-AS1 predicted poor prognosis for patients with PTC and promoted cell proliferation and metastasis in vitro and in vivo. ABHD11-AS1 was activated by the transcription factor STAT3. ABHD11-AS1 positively regulated PI3K/AKT signalling pathway. ABHD11-AS1 acted as a competitive endogenous (ce) RNA to upregulate STAT3 by sponging miR-1301-3p.Conclusions: STAT3-induced lncRNA ABHD11-AS1 promoted PTC progression by regulating PI3K/AKT signalling pathway and miR-1301-3p/STAT3 axis.

How mutations or dysfunction of CFTR may increase the risk of malignancies in various tissues remains an open question. Here we report the interaction between CFTR and an adherens junction molecule, AF-6/afadin, and its involvement in the development of colon cancer. We have found that CFTR and AF-6/afadin are co-localized at the cell-cell contacts and physically interact with each other in colon cancer cell lines. Knockdown of CFTR results in reduced epithelial tightness and enhanced malignancies, with increased degradation and reduced stability of AF-6/afadin protein. The enhanced invasive phenotype of CFTR-knockdown cells can be completely reversed by either AF-6/afadin over-expression or ERK inhibitor, indicating the involvement of AF-6/MAPK pathway. More interestingly, the expression levels of CFTR and AF-6/afadin are significantly downregulated in human colon cancer tissues and lower expression of CFTR and/or AF-6/afadin is correlated with poor prognosis of colon cancer patients. The present study has revealed a previously unrecognized interaction between CFTR and AF-6/afadin that is involved in the pathogenesis of colon cancer and indicated the potential of the two as novel markers of metastasis and prognostic predictors for human colon cancer.

MTSS1 (metastasis suppressor-1) was first identified as a metastasis suppressor missing in metastatic bladder carcinoma cell lines. The down-regulation of MTSS1 that may be caused by DNA methylation was also observed in many other types of cancer. While accumlating evidence for the function of MTSS1 support the concept that it is unlikely to be a metastasis suppressor, but actually acts as a scaffold protein that interacts with multiple partners to regulate actin dynamics. It has also been demonstrated that MTSS1 is involved in the Shh signaling pathway in the developing hair follicle and in basal cell carcinomas of the skin. Such evidence indicates that MTSS1 as a multiple functional molecular player and has an important role in development, carcinogenesis and metastasis. However, the biochemical mechanisms by which MTSS1 functions in cells and the physiological role of this protein in animals remain largely unknown. In this review, we will discuss the current knowledge of MTSS1's role in cancer metastasis, carcinogenesis, and development. The clinical significance of MTSS1 will also be discussed.