Apoptosis Of Laryngeal Squamous Cell Carcinoma Induced By Celecoxib And The Mechanism

Laryngeal cancer is the most common malignancies in otolaryngology-head and neck surgery. The incidence of laryngeal cancer shows an increasing trend because of the environmental pollutions. As the same as all other malignancies, various factors contribute to the oncogenesis of laryngeal cancer, such as smoking, alcohol, air pollution, viral infection, genetic background, sex hormone and so on. Although the operation technique has been improved greatly, the management of advanced laryngeal cancer continues to be a challenging clinical problem. Traditional treatments of surgery and/or radiation have not yielded significant improvements in survival in this patient population. More methods is being studies by researchers. Compared with traditional treatment modalities, chemotherapy given on induction schedules to patients with advanced laryngeal cancer allows greater organ preservation without compromise to survival; when given concomitantly with radiotherapy to patients with resectable or unresectable advanced disease, chemotherapy again improves survival. Over expression of cyclooxygenase-2 in head and neck cancer supply a new target for cancer therapy. We explore the effects of selective COX-2 inhibitor celecoxib on laryngeal cancer cells and the related mechanisms. Ⅰ. Expression of COX-2 in laryngeal cancer The expression of COX-2 in 42 laryngeal cancer specimens, 20 non-tumor adjacent tissues, 20 laryngeal keratosis specimens, and 10 normal laryngeal mucosa specimens were detected by immunochemistry. COX-2 expression was detected in 73.8%, 55.0%, and 45.0% in laryngeal cancer samples, non-tumor adjacent tissues and keratosis respectively. No COX-2 expression was detected in normal laryngeal mucosa (laryngeal cancer vs. normal mucosa P<0.01, non-tumor adjacent tissues vs. normal mucosa P<0.05, keratosis vs. normal mucosa P>0.05, laryngeal cancer vs. non-tumor adjacent tissues P>0.05, laryngeal cancer vs. keratosis P<0.05). Overexpression was significantly associated with N staging and pathological grading (P<0.01; P<0.01) while no relationship was drew with the location of the lesions, age, gender, T staging, and TNM staging. Ⅱ. Effects of celecoxib on laryngeal carcinoma cells Effects of celecoxib on Hep-2 cells and HpEGF/Survivin-1(hps-1 for short) were observed through phase-contrast microscope, cell growth curve, MTT assay, flow cytometry, and Western blot. Under the microscope apoptotic cells increased as the concentration of celecoxib increased. From 3μmol/L to 100μmol/L, as the celecoxib concentration increased the growth curves of hep-2 and hps-1 became flatter. From 10μmol/L to 100μmol/L, as the celecoxib concentration increased the proliferation activity curves of hep-2 and hps-1 became flatter. Compared with control the differences were significant at 10μmol/L, 30μmol/L, 100μmol/L (P<0.05). The inhibitory rates of 10μmol/L, 30μmol/L, 100μmol/L celecoxib were higher than that of1μmol/L (P<0.05). There was no or very low apoptosis peak in the flow cytometry figure of control hep-2 cells. Other groups have different apoptosis peak. The apoptosis rates differ significantly among 10μmol/L, 30μmol/L celecoxib and control (P<0.05). At the same celecoxib concentration the apoptosis rates of hep-2 and hps-1 are significantly different (P<0.05). Western blot of bcl-2 shows differences among 10μmol/L, 30μmol/L celecoxib and control (P<0.05). No difference was observed between hep-2 and hps-1 cells. We draw the conclusion that the induction of apoptosis by celecoxib is partially by the bcl-2 pathway. Ⅲ. Celecoxib combined with trentinoin induces apoptosis of hep-2 cells Effects of celecoxib combined with trentinoin on Hep-2 cells were observed through phase-contrast microscope, cell growth curve, MTT assay, flow cytometry, and Western blot. From 1μmol/L to 30μmol/L, as the tretinoin concentration increased the proliferation activity curves of hep-2 became flatter. Compared with control the differences were significant at 1μmol/L, 10μmol/L, 30μmol/L (P<0.05). The inhibitory rates of 10μmol/L, 30μmol/L, 100μmol/L tretinoin combined with 30μmol/L celecoxib were higher than those of 10μmol/L, 30μmol/L, 100μmol/L trentinoin respectively (P<0.05). There was no or very low apoptosis peak in the flow cytometry figure of control hep-2 cells. Other groups have different apoptosis peak. The apoptosis rates differ significantly among 10μmol/L, 30μmol/L tretinoin and control (P<0.05). At the same tretinoin concentration the apoptosis rates of tretinoin and tretinoin combined with30μmol/L celecoxib are significantly different (P<0.05). Western blot of bcl-2 shows differences between 30μmol/L celecoxib, 30μmol/L tretinoin and control (P<0.05). The expression of bcl-2 in...