RESUMEN
A previous study has reported that knockdown of RING finger protein 2 (RNF2) increases the radiosensitivity of esophageal cancer cells both in vitro and in vivo. However, the effect of RNF2 knockdown on radiosensitivity in squamous cell carcinoma (SqCC) remains unknown. For this, NCI-H226 and SK-MES-1 cells were exposed to X-ray irradiation and then RNF2 levels were determined. RNF2 was knocked-down and stable transfectants were selected. Radiosensitivity, cell proliferation, apoptosis, cell cycle, and γ-H2AX foci formation were evaluated. Interaction among ataxia telangiectasia mutated protein (ATM), mediator of DNA damage checkpoint 1 (MDC1), and H2AX were examined. Xenograft models were used to explore the effect of RNF2 knockdown on radiosensitivity in vivo. The results showed that RNF2 expression was significantly increased by X-ray irradiation. RNF2 knockdown combined with X-ray irradiation markedly inhibited cell proliferation, caused cell cycle arrest at the G1 phase, and induced cell apoptosis. In addition, RNF2 knockdown enhanced the radiosensitivity of SqCC cells, inhibited irradiation-induced γ-H2AX foci formation, and impaired the interactions among ATM, MDC1, and H2AX. Furthermore, combination of RNF2 knockdown and X-ray irradiation suppressed tumor growth and promoted tumor cell apoptosis in vivo. RNF2 may be a new therapeutic target to enhance the radiosensitivity of SqCC cells in lung.
Asunto(s)
Carcinoma de Células Escamosas/radioterapia , Neoplasias Pulmonares/radioterapia , Complejo Represivo Polycomb 1/deficiencia , Complejo Represivo Polycomb 1/metabolismo , Tolerancia a Radiación , Apoptosis , Carcinoma de Células Escamosas/patología , Proliferación Celular , Histonas/metabolismo , Humanos , Neoplasias Pulmonares/patología , Células Tumorales Cultivadas , Rayos XRESUMEN
PURPOSE: This study evaluated the efficacy and safety of the combination drug tegafur, gimeracil, and oteracil potassium (S-1) concurrent with 3-dimensional conformal radiotherapy for newly diagnosed squamous cell carcinoma of the lung in elderly patients. PATIENTS AND METHODS: Patients with pathologically or cytologically newly diagnosed lung squamous cell carcinoma (n=106) were randomly assigned to receive the combination of tegafur, gimeracil, and oteracil potassium (40mg/m(2), BID, d1-28, repeated every 6 weeks for 4 cycles) and concurrent 3D-conformal radiotherapy (60Gy; experimental group), or gemcitabine (800-1000mg/m(2), d1 and d8) repeated every 21 days for 4 cycles as well as 3D-conformal radiotherapy (control group). RESULTS: The overall response rate (complete and partial responses) of the experimental group was 68.6%, which was significantly higher than that of the control group (38.5%; P=0.002). The median progression-free survival rates of the experimental and control groups were 11.8 months (95% confidence interval [CI]: 8.0-22.4) and 7.8 months (95% CI, 6.9-9.2), respectively (P=0.017). Adverse reactions included grade I/II radiation esophagitis and pneumonitis, with good tolerance. Grade III/IV adverse reactions of the experimental and control groups were leucopenia (20% cf. 56.6%, respectively; P=0.027), thrombocytopenia (3.9% cf. 25%; P=0.037), and gastrointestinal reaction (1.9% cf. 3.5%; P=0.35). CONCLUSION: The efficacy of concurrent combination chemotherapy with tegafur, gimeracil, and oteracil potassium (S-1) and 3D-conformal radiotherapy for newly diagnosed squamous cell carcinoma of the lung in elderly patients was excellent, and all toxicities were well tolerated. This treatment might be considered a main regimen in the management of squamous cell carcinoma of the lung in elderly patients.