WWOX suppresses KLF5 expression and breast cancer cell growth

The WW domain-containing oxidoreductase（WWOX） is a tumor suppressor in a variety of cancers, including breast cancer. Reduced WWOX expression is associated with the basal-like subtype and a relatively poor disease-free survival rate among breast cancer patients. Though several WWOX partners have been identified, the functional mechanisms of WWOX＇s role in cancers have not been fully addressed to date. In the current study, we found WWOX suppresses expression of KLF5—an oncogenic transcription factor—at protein level, and suppresses cancer cell proliferation in both bladder and breast cancer cell lines. Furthermore, we demonstrated that WWOX physically interacts with KLF5 via the former＇s WW domains and the latter＇s PY motifs. Interestingly, we found the expression of WWOX negatively correlates with KLF5 expression in a panel of breast cancer cell lines. Taken together, we conjecture that WWOX may suppress cancer cell proliferation partially by reducing the expression of KLF5.

Cloning of WWOX Gene and Its Growth-inhibiting Effects on Ovarian Cancer Cells

The growth-inhibiting and apoptosis-inducing effects of WW domain-containing oxidoreductase(WWOX) gene on ovarian cancer cell line A2780 were investigated.The full length cDNA of human WWOX gene was amplified from normal human ovary tissues.The correct cDNA of full length WWOX was subcloned into eukaryocytic expression vector pCMV.After introduction of WWOX gene into cancer cells with liposome,the WWOX mRNA and protein level in the cancer cells were detected by reverse transcription polymerase chain reaction(RT-PCR) and immunoblotting.The growth activities of cancer cells were detected by Trypan blue staining.The clone formation assay in soft agar was employed to observe the proliferation of the cancer cells.Apoptosis was examined by DNA ladder and acridine orange-ethidium bromide fluorescent staining.The results showed that 72 h after WWOX gene transfection,the WWOX expression was increased significantly(P<0.01).The growth of ovarian cancer cells was decreased by 16.41% to 38.49%(P<0.01).The clone formation abilities were reduced(P<0.01).Some cancer cells presented the characteristic morphological changes of apoptosis with obvious ladder bands on electrophoresis.The apoptosis rate was(20.7±6.0)%(P<0.01).It was concluded that over-expression of WWOX gene could induce apoptosis and inhibit the growth of ovarian cancer cells,which might be potentially useful in the gene therapy of ovarian cancers.

Reverse effect of Semaphorin-3F on rituximab resistance in diffuse large B-cell lymphoma via the Hippo pathway

Background:Exploring the underlying mechanism of rituximab resistance is critical to improve the outcomes of patients with diffuse large B-cell lymphoma(DLBCL).Here,we tried to identify the effects of the axon guidance factor semaphorin-3F(SEMA3F)on rituximab resistance as well as its therapeutic value in DLBCL.Methods:The effects of SEMA3F on the treatment response to rituximab were investigated by gain-or loss-of-function experiments.The role of the Hippo pathway in SEMA3F-mediated activity was explored.A xenograft mouse model generated by SEMA3F knockdown in cells was used to evaluate rituximab sensitivity and combined therapeutic effects.The prognostic value of SEMA3F and TAZ(WW domain-containing transcription regulator protein 1)was examined in the Gene Expression Omnibus(GEO)database and human DLBCL specimens.Results:We found that loss of SEMA3F was related to a poor prognosis in patients who received rituximab-based immunochemotherapy instead of chemotherapy regimen.Knockdown of SEMA3F significantly repressed the expression of CD20 and reduced the proapoptotic activity and complement-dependent cytotoxicity(CDC)activity induced by rituximab.We further demonstrated that the Hippo pathway was involved in the SEMA3F-mediated regulation of CD20.Knockdown of SEMA3F expression induced the nuclear accumulation of TAZ and inhibited CD20 transcriptional levels via direct binding of the transcription factor TEAD2 and the CD20 promoter.Moreover,in patients with DLBCL,SEMA3F expression was negatively correlated with TAZ,and patients with SEMA3F^(low)TAZ^(high)had a limited benefit from a rituximab-based strategy.Specifically,treatment of DLBCL cells with rituximab and a YAP/TAZ inhibitor showed promising therapeutic effects in vitro and in vivo.Conclusion:Our study thus defined a previously unknown mechanism of SEMA3F-mediated rituximab resistance through TAZ activation in DLBCL and identified potential therapeutic targets in patients.