KNSTRN Promotes Tumorigenesis And Gemcitabine Resistance By Activating AKT In Bladder Cancer

Objective Bladder cancer patients remain a poor prognosis caused by metastasis and chemotherapy resistance.It is critical to better understand the molecular mechanisms of bladder cancer carcinogenesis in order to serve for the development of new treatments.KNSTRN is a component of the mitotic spindle which was rarely investigated in tumorigenesis.This study aims to reveal the function of KNSTRN in metastasis and gemcitabine resistance of bladder cancer.Methods We identified the clinical relevance of KNSTRN in bladder cancer by bioinformatics.Then,we detected the expression of KNSTRN in bladder cancer tissues and cell lines by Western blot,RT-q PCR and immunohistochemistry assay.Furthermore,the effect of KNSTRN on bladder cancer proliferation,metastasis and gemcitabine resistance was investigated by a series of in vitro and in vivo experiments.In addition,the relationship between KNSTRN and AKT was proved by immunofluorescence,Co-IP,GST pull-down and PIP₃ pull down.Finally,Western blot,Transwell and MTT assay was applied to study whether AKT can restore the effect of KNSTRN on the proliferation,metastasis and gemcitabine resistance of bladder cancer.Results We proved KNSTRN is positively correlated with malignancy of bladder cancer and demonstrated KNSTRN promotes bladder cancer metastasis and gemcitabine resistance in vitro and in vivo.In addition,KNSTRN activates AKT phosphorylation at Thr308 and Ser473.More importantly,our study revealed that both KNSTRN and PTEN interact with PH domain of AKT at cell membrane.The amount of KNSTRN interacted with AKT was negatively related to PTEN.Furthermore,PIP₃pull-down assay proved that KNSTRN promoted AKT movement to PIP₃.These data suggested KNSTRN may activate AKT phosphorylation by promoting AKT movement to PIP₃ and alleviating PTEN suppression.Based on the activation of AKT phosphorylation,our study revealed that the effect of KNSTRN on bladder cancer tumorigenesis and gemcitabine resistance could be restored by AKT specific inhibitor MK2206 or AKT overexpression.Conclusions We identify an oncogene KNSTRN which is highly related to the malignancy and prognosis of bladder cancer.KNSTRN promotes bladder cancer tumorigenesis and gemcitabine resistance by activating AKT phosphorylation and may serve as a therapeutic target in bladder cancer.