Research Paper Volume 16, Issue 11 pp 9410—9436

Figure 1. PIK3CA-E545K promotes L-OHP resistance in colorectal cancer cells. (A) Protein levels of PIK3CA, Flag and β-actin in PIK3CA-E545K infected HCT116 and SW480 cells were analyzed by Western blotting. β-actin was used as loading control. (B) IC₅₀ of L-OHP was determined by treating PIK3CA-E545K or empty vector infected HCT116 cells in a dose dependent manner. (C) Infected HCT116/E545K cells were challenged with L-OHP (2 μM), which showed increased resistance to L-OHP than the control. (D) Western blot analysis of Bcl-2 and Survivin expression in PIK3CA-E545K infected HCT116 and SW480 cells following 2 μM L-OHP treatment. (E) The percentage of cell apoptosis activation after 48 hours of 2 μM L-OHP exposure was measured by FITC-Annexin V/PI double staining of flow cytometry. (F) IC₅₀ of primary colon cancer cells, CC-1 and CC-2, were analyzed with cell viability with gradient L-OHP treatment. Their IC₅₀ were 5.98 μM and 0.15 μM, respectively. (G) Cell apoptosis percentage of CC-1/2 with L-OHP treatment was analyzed as (E). Results are representative of at least three independent experiments. (H) Effect of PIK3CA-E545K expression in L-OHP resistance in vivo was analyzed with subcutaneously injected HCT116 cells (n = 6 each group). L-OHP (10 mg/kg) was intraperitoneally administrated once every 3 days. Xenograft tumor volumes were measured with a caliper. The tumor growth inhibition was calculated. p-values < 0.05 are represented as a^*.