Expression of factors and key components associated with the PI3K signaling pathway in colon cancer

The pathophysiology of colorectal cancer (CRC) has not been fully elucidated. The dysregulation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway frequently contributes to the tumorigenesis and progression of human cancer. The aim of the present study was to explore the expression and clinical significance of a number of associated factors and key components of the PI3K signaling pathway, including phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (p110α), phosphorylated protein kinase B (p-Akt) Ser473, p-mammalian target of rapamycin (mTOR) Ser2448, cyclin D1, cyclin dependent kinase (CDK)4, RELA proto-oncogene, nuclear factor-κβ subunit (p65), Ras and extracellular signal-regulated kinase (ERK)1/2 in human CRC. The expression of target proteins was detected using immunohistochemistry (IHC) in 65 CRC cases and 15 colonic adenoma cases. The association between the expression of target proteins and clinical pathological parameters was analyzed using a χ(2) test. IHC results revealed that the expression of all target proteins was significantly increased in CRC tissues compared with in colonic adenoma tissues (P<0.05). No significant associations were observed between the expression of p110α, p-Akt Ser473, p-mTOR Ser2448 and sex, age, differentiation, lymph node metastasis or Tumor-Node-Metastasis staging (P>0.05). Cyclin D1, CDK4 and Ras were revealed to be expressed significantly higher in poorly differentiated CRC compared with moderately differentiated CRC (P<0.05). Expression of p65 and ERK1/2 were significantly increased in cancer tissues with lymph node metastasis compared with cancer tissues without lymph node metastasis (P<0.05). These results suggest that the target proteins may all participate in the tumorigenesis of CRC. Furthermore, cyclin D1, CDK4, Ras, p65 and ERK1/2 may be important in the progression of CRC. The results of the present study may provide novel predictive factors and therapeutic targets for CRC.