Study of signal transduction mechanisms of X-ray induced multidrug resistance in nasopharyngeal squamous cell carcinoma CNE1 cells

Abstract

Objective To investigate the relationship between multidrug resistance of X-ray irradiated human nasopharyngeal squamous carcinoma cell line CNE1 and platelet endothelial cell adhesion molecule-1 (PECMA-1)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/Bcl-2 signaling pathway. Methods ①The CNE1 cells were cultured in incubator. Exponentially growing CNE1 cells were exposed to 50 Gy ionizing radiation administered in 25 fractions, 2 Gy per fraction, once every two days, and the CNE1/R cells were collected. ②CNE1/R cells were cultured for 24 h, and divided into three groups: the control group, experimental group one (CNE1/R cells were processed through 1∶600 PECAM-1 antibody for 24 h) and experimental group two (CNE1/R cells were processed through 10 μmol/L PI3K inhibitor LY294002 for 24 h). ③The half maximal inhibitory concentration (IC50) values of the control group and two experimental groups of CNE1/R cells were detected by methyl thiazolyl tetrazolium (MTT). ④The mRNA expressions of PI3K and Bcl-2 in the control group and experimental group one were measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). ⑤The mRNA expressions of AKT and Bcl-2 in the control group and experimental group two were measured by semi-quantitative RT-PCR. Results ①The IC50 of the control group, experimental group one and two were (2.99±0.02)μg/ml, (1.50±0.03)μg/ml and (1.60±0.05)μg/ml, and the difference among the three groups was statiatically signficant (F=4 381.263, P=0.000). The IC50 of the two experimental groups were obviously lower than that of the control group (t=116.885, P=0.000; t=73.006, P=0.000). ②The semi-quantitative values of PI3K in the control group and experimental group one were 1.66±0.01 and 0.90±0.05 (t=50.394, P=0.000), and the semi-quantitative values of Bcl-2 were 1.66±0.02 and 0.71±0.05 (t=183.165, P=0.000), and the differences were statistically significant. ③The semi-quantitative values of AKT of control group and experimental group two were 1.53±0.01 and 0.72±0.01 (t=135.281, P=0.000), and the semi-quantitative values of Bcl-2 were 1.66±0.02 and 0.63±0.02 (t=128.814, P=0.000), and the differences were statistically significant. Conclusion PECAM-1 induced multidrug resistance of human nasopharyngeal squamous cell carcinoma CNE1 cells may be related to the activity of Bcl-2 through the signal pathway of PI3K/AKT. Key words: Nasopharyngeal neoplasms; Drug resistance, neoplasm; Antigens, CD31; X-rays