Cytohesin SiRNA Induces Apoptosis And Insulin Like Growth Factor Receptor Signaling Reduction In Multidrug Resistant And Rogen-in Dependent Prostate Cancer

Prostate cancer cell multidrug resistance (MDR) is a common cause offailure in clinical prostate cancer chemotherapy. How to build efficient,low-toxic reversal agents against MDR is the focus of prostate cancer treatment.The tolerance of multidrug resistant tumor cells to chemotherapeuticdrug-induced apoptosis plays a certain role in the MDR formation. Therefore,to look for ways to promote prostate cancer multidrug resistant cell apoptosis,may reduce the resistance of multidrug resistant tumor to a certain extent.Cytohesins, a group of adenosine diphosphate ribosylation factor (ARF)guanosine triphosphatase guanine nucleotide exchange factors, have recentlybecome one of the important biological signal transduction regulators invertebrate and invertebrate. They play the role of regulating cytoskeletalassembly and integrating activation and the signal system. Cytohesinsassociated with the insulin receptor complex are necessary for the insulinsignaling system in the liver cells. Inhibition of cytohesins led to hepatic insulinresistance. In prostate cancer cells PC-3M, cytohesins is linked to insulin-likegrowth factor-1(IGF-I) signaling system. To inhibit cytohesins cansuccessfully induce PC-3M cells apoptosis through the AKT/PKB signalingpathway. NF-κB (nuclear factor-kappa B) is distributed and acted in a widerange as the eukaryotic transcription factor related to MDR of tumor cellsthrough multiple signaling pathways. In the leukemia cell, NF-κB regulatesMDR1gene and is involved in resistance reversal. NF-κB, Bcl-2and p53molecules are closely related to the occurrence and development of prostatetumor cells. Insulin-like growth factor-1(IGF-I) and its receptor (IGF-IR) are linked totumor cell apoptosis, transformation, invasive growth and distant metastasis.The level of tumor cell expression of IGF-IR, to some extent, determines thetumorigenic and metastatic nature of the tumor cells. To block IGF-IR signaltransduction will restore the phenotype of the cells, promote apoptosis, improvechemotherapy drug sensitivity, and reduce the tendency of the tumor cellmetastases. The combination of IGF-I and IGF-IR to activate downstreamsignaling pathways has a wide range of biological effects, and also plays animportant role in prostate cancer progression and metastasis. IGF-I is greatlylinked to insulin. Insulin-like growth factor receptor (IGFR) and insulinreceptor (IR) share the same signal transduction pathway. Therefore,Cytohesins may play an important role in the IGF-IR signal transduction ofprostate cancer and influence the proliferation and apoptosis of prostate cancer.Objective: The research is to study the cytohesin siRNA inducingapoptosis in multidrug resistant androgen-independent prostate cancer cells, themechanism of MDR reverse, and the reduction of the insulin like growth factorreceptor signaling pathway.Methods:Multidrug resistant androgen-independent prostate cancer cellsPC-3M/CDDP were treated with the cytohesin(cyth)-1siRNA. mRNA andprotein expression of the apoptotic genes, the multidrug resistance genes andinsulin like growth factor receptor signaling pathway molecules were detectedby quantitative PCR and Western blotting.Results:Cytohesin-1siRNA inhibits cyth-1gene expression, and then,reduces NF-κB signaling pathway and multidrug resistance gene mdr1expression, promotes multidrug resistance reversal, downregulates the bcl-2gene, activates p53, and promotes multi-resistant cell apoptosis. By cyth-1siRNA interference, the relative mRNA levels of CYTH-1, c-Myc, cyclinD1,and IGF-IR (CYTH-1siRNA group vs scrambled siRNA group) were0.26vs 0.97,0.34vs1.06,0.10vs0.95and0.27vs0.41(P <0.05,for all), respectively.The relative protein levels of CYTH-1, pIGF-IR, pIRS1, pAkt1, pErk1, c-Myc,and cyclinD1(CYTH-1siRNA group vs scrambled siRNA group) were0.10vs1.14(10min),0.10vs1.12(10min),0.04vs0.57(10min),0.10vs1.14(1h),0.10vs1.14(1h),0.13vs0.97(7h)和0.08vs0.91(7h), respectively.The tyrosine kinase activity of IGF-IR was associated with CYTH-1. Theproliferative activity of PC-3M/CDDP cells transfected with CYTH-1siRNAwas significantly lower than those of cells transfected with scrambled siRNA at48h (40.5vs87.6%, P <0.05) and at72h (34.5vs93.5%, P <0.05). The goodperformance of the drug SecinH3was found to suppress CYTH-1and inhibitthe IGF-1R signaling pathway, similar to the role of CYTH-1siRNA and in adose-dependent manner. SecinH3may be used as cytohesins inhibitor inclinic.Conclusion: Cytohesin-1siRNA reduces NF-κB signaling pathway andpromotes apoptosis and the MDR reversal of tumor cell with multidrugresistance. Cytohesins play an important role in prostate cancer IGFR signaltransduction. SiRNA interference with cytohesins can reduce prostate cancerIGFR signaling. Thus cytohesins may become a new target for the treatment ofprostate cancer.