The Effect Of PIK3R3 On Prognosis And Chemosensitivity In Colorectal Cancer

Objective: Our research group has been studying the important role of regulatory subunit of the Phosphatidylinositol 3 – kinase(PI3K),PIK3R3,signal transduction pathway in colorectal cancer(CRC).Previously we have reported that PIK3R3 was increased in CRC patients,these results were indicated that PIK3R3 has critical impact on CRC development.On one hand,PIK3R3 could increase the proliferation of tumor cells by combined with RB and PCNA,which is the two main protein regulating cell cycle.On the other hand,PIK3R3 could enhance angiogenesis of colorectal cancer by activating the NF-k B signaling pathway in an AKT independent manner,and.But the prognosis effect of PIK3R3 in CRC patients is still remaining unclear.In this study we try to determine whether PIK3R3 could be considered as a predictor in patients with CRC.Method: In this study,Clinical data was downloaded from The Cancer Genome Atlas(TCGA)and three different microarray datasets from GEO.These datasets following criteria:(1)Obtained using a similar chip platform(Affymetrix,GPL570).(2)All data were available in recent ten years.(3)Patients survival information was available.(4)Obtaining no less than 150 patients sample in each group.Overall survival(OS)and disease free survival(DFS)was measured by Kaplan-Meier method.Results: First,patients from TCGA were divided in to two groups,high and low expression of PIK3R3.Analyzed the difference of overall survival(OS)and disease free survival(DFS)between those two groups.Data showed that the patients with higher expression of PIK3R3 has better DFS,but there is no significant difference in OS.For further we were downloaded three different microarray datasets from GEO,and analyze the prognosis differences between higher and lower expression of PIK3R3.Same with our previous result,patients with higher expression of PIK3R3 had better DFS than those with lower expression of PIK3R3,but not significant difference can observe in OS.Conclusion: PIK3R3 could prolonged DFS in CRC patients,but has no effects on OS.PIK3R3 could be considered as a prognosis predictor for CRC Objective: In our previous study we have found that high level of PIK3R3 were indicated better disease free survival(DFS),but has no effect on overall survival in different clinical database.However,the mechanism in here is not clear.Thymidine phosphorylase(TP),also known as platelet derived endothelial cell growth factor(PD-ECGF),is the key enzyme for 5-fluorouracil(5-FU)and its prodrugs,such as capecitabine,transformed to their final active forms.Chemotherapy is one of the main reason to improve patient’s clinical outcome,and 5-FU is the most popular chemo-drugs used in clinical treatment.In this study we were trying to understand the mechanism of TP expression by regulated PIK3R3.Method: Colorectal cell lines were transfected with PIK3R3 plasmids or si RNAs to interfere the expression of PIK3R3.Protein and m RNA expression level changes of TP were detected by using WB and QPCR,respectively.We then analyzed the expression level of TP and PIK3R3 in primary tumors from 20 patients by immunohistochemical(IHC).Next we were using the database to analyze correlation of PIK3R3 and TP.Finally we were able to uncover the pathway between PIK3R3 and TP Results: Cells were treated with PIK3R3 plasmids were observed increase level of TP both in protein and m RNA.However,on the contrary TP level were decreased in the cells were transfected with si RNAs.We then analyzed the expression level of TP and PIK3R3 in primary tumors from 20 patients by IHC.Data showed that upregulated TP was observed in patients with overexpressed PIK3R3.We also noticed that the expression of PIK3R3 was positively correlated with TP expression,and this was verified by database which was used in previous study.Finally we have found that PIK3R3 regulated the expression of TP by activating of NF-Kb.This type of effect will reverse when the cells were treated with NF-k B inhibitor.Conclusion: PIK3R3 regulated the expression of TP through activating NF-k B pathway in CRC cell lines.Objective: Previously we have found PIK3R3 could regulate TP expression,which is the key enzyme for 5-FU metabolism.Moreover,we have investigated that NF-k B pathway was required on this process.In this study we will explain the role of PIK3R3 in 5-FU therapy in colorectal cancer.Method: First,we established stabilized PIK3R3 overexpressing Cells,and tested the expression of PIK3R3 and TP expression level by western blot and QPCR to sure the experiment was successful.To further study the role of PIK3R3 in 5-FU therapy.Cells were treated with DMSO or 5-FU,cell cycle,cell apoptosis were tested in each group.Finally,animal study were used to confirm the results were observed in vitro.Results: PIK3R3 overexpressed stabilized cells were significantly increased the expression of TP.Cell survival and the percentage of S phase in cell cycle were increased in PIK3R3 overexpressed cells when treated with DMSO,but there is no differences in cell apoptosis.These results were same with our previous report.However,increased cell apoptosis and decreased cell survival were observed in PIK3R3 overexpressed cells when they were treated with 5-FU.Animal study revealed that tumors with overexpressed PIK3R3 showed sharp increases in tumor size and weight when compared with those carrying vectors without 5-FU treatment.Interestingly,we found obviously low tumor progression in the PIK3R3-overexpressing group,when mice treated with 5-FU.Conclusion: PIK3R3 could improve tumor development in CRC.However,when treated with 5-FU,PIK3R3 could enhance chemotherapeutic sensitivity by increasing cell apoptosis.