Alterations of cell cycle control proteins SHP?1/2, p16, CDK4 and cyclin D1 in radioresistant nasopharyngeal carcinoma cells.

ABSTRACT: The primary treatment for nasopharyngeal carcinoma (NPC) is radiotherapy, with or without concurrent chemotherapy. However, resistance to radiotherapy is not uncommon. The aim of the present study was to establish a radioresistant NPC cell line to study the molecular mechanisms of radioresistance by measuring the expression of cell cycle control proteins src homology 2 domain-containing phosphatase (SHP)-1/2, p16, CDK4 and cyclin D1. Human nasopharyngeal carcinoma CNE?2 cells were cultured, divided into two groups (CNE-2S1 and CNE-2S2) and irradiated with a dose of 6 Gy x5 or 2 Gy x15, respectively. The cells were subcultured between doses of irradiation. The surviving sublines (CNE-2S1 and CNE-2S2 clones) were then passaged for three months and their radiosensitivity was determined. The cell cycle distribution and protein expression of SHP-1/2, p16, CDK4 and cyclin D1 in parental and progenitor cell lines were measured. Small interfering (si)RNA-mediated knockdown of SHP-1 and SHP?2 in the NPC cells was used to further examine their roles in radiosensitivity and cell cycle distribution. CNE-2S1, a radio?resistant cell line, had a significantly higher percentage of cells in S phase and a lower percentage of cells in G1 phase, enhanced expression levels of SHP-1, CDK4 and cyclin D1, and reduced expression of p16, respectively, as compared with the parent cells. Stable suppression of SHP-1 mRNA in CNE?2 cells resulted in increased radiosensitivity compared with the parental cells, a decrease in the number of cells in S phase and an increase in the expression of p16. The results suggested that the SHP?1/p16/cyclin D1/CDK4 pathway may have a role in regulating radiosensitivity and cell cycle distribution in nasopharyngeal cells.

SUBMITTER: Peng G 

PROVIDER: S-EPMC4148372 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature