PIK3CA expression in diffuse large B cell lymphoma tissue and the effect of its knockdown in vitro.

PIK3CA has been extensively investigated from its molecular mechanism perspective and epidemiological association with its mutations in different types of cancers. However, little has been reported regarding the clinicopathological significance of PIK3CA expression in diffuse large B cell lymphoma (DLBCL). In the present study, we investigated the clinicopathological significance of PIK3CA in DLBCL by performing immunohistochemical evaluation of PIK3CA in tissue microarrays consisting of 199 cases of DLBCL. Kaplan-Meier survival analysis was performed to analyze the association between PIK3CA expression and overall prognosis. To further investigate the role of PIK3CA mediated in the proliferation, cell cycle and apoptosis of DLBCL cells, Cell Counting Kit-8 (CCK-8) and flow cytometry assays were carried out in DLBCL cell lines after successful, stable knockdown of PIK3CA using lentiviral short hairpin RNA inference. Our results indicated that although PIK3CA was shown to be extensively expressed in DLBCL, no significant association was observed between PIK3CA expression and clinical outcome or between PIK3CA expression and other clinicopathological parameters, except between performance state (PS) and phosphorylated AKT (p-AKT) expression. In vitro studies revealed that in DLBCL cell lines OCI-LY8 and OCI-LY1, knockdown of PIK3CA could significantly reduce proliferation and promote apoptosis in a G1-phase arrested manner. Additionally, p27 was shown to be markedly upregulated, whereas p-AKT and cyclin D1 were found to be pronouncedly downregulated after stable knockdown of PIK3CA. Together, our results support the oncogenic property of PIK3CA in DLBCL.