| Objectives:To study the clinical significance of Beclin 1 in oral squamous cell cancer(OSCC)and its relationship with mTOR(mammalian target of rapamycin),MAP1LC3B(Microtubule associated protein 1 light chain 3B),bcl-2(B-cell lymphoma-2),survivin and bax in oral carcinogenesis;and to investigate the effects of biological characteristics and sensitivity to cisplatin of OSCC cells.Methods:Immunohistochemical SP method was used to detect the expression of Beclin 1,mTOR,MAP1LC3B,bcl-2,survivin and bax in oral carcinogenesis tissues including oral cancer(60 cases),oral dysplasia(48 cases)and normal oralmucosa(60 cases),and to study the clinical significance of Beclin 1 in OSCC and its relationship with mTOR,MAP1LC3B,bcl-2,survivin and bax expression in oral carcinogenesis.After Beclin 1 was silenced by small interfering RNA technology in OSCC cells,the effects of biological characteristics(including cell hyperplasia,migration,invasion and apoptosis)on OSCC cells were explored through transmission electron microscopy(TEM),real-time PCR,western blot,cell counting kit-8(CCK-8),clone formation experiment,cell cycle detection and Annexin V-FITC/PI apoptosis detection techniques.Furthermore,the effect on chemosensitivity to cisplatin after Beclin 1 gene silencing was investigated.SPSS 19.0 software was used to analyze the data.T test was used to compare the mean data of two samples,and chi-square test was used to conducted the comparison of the two sample rates,p<0.05 was considered statistically significant.Results:1.The expression rate of Beclinl was 75%in normal mucosa,and 65%in OSCC while the expression in dysplasia(54.2%)was lower than normal mucosa(p<0.05).The positive expression rate of mTOR in OSCC and dysplasia was 75%and 66.7%respectively,which was significantly higher than in normal mucosa(p<0.05).The expression of MAPILC3B was higher in normal mucosa(78.3%),while in dysplasia and in OSCC MAP1LC3B expression decreased significantly(27.1%?58.3%;p<0.05).The integral optical density(IOD)of expression of Beclinl,mTOR and MAP1LC3B proteins was significantly higher in the center than in peripheral of tumor(p<0.05).Beclin1,mTOR,MAP1LC3B expression was related to lymph node metastasis and TNM stage of oral cancer(p<0.05).The expression of Beclinl,MAP1LC3B was also closely related to smoking.2.Bcl-2 and survivin expression were higher in OSCC(70%;73.33%)than in dysplasia and in normal mucosa.Bax expression rate was 77.08%,which was higher than in OSCC and normal mucosa(p<0.05).Bcl-2,survivin and bax expression was closely related to diameter of tumor and lymph node metastasis(p<0.05).The expression of Beclin1 was closely related to bcl-2,survivin and bax(p<0.05;.r=0.421,0.367 and 0.542)in OSCC.While in dysplasia Beclinl was only closely related to survivin(r=0.613).3.When Beclin 1 was silenced,autophagosomes in OSCC cells decreased obviously;cell proliferation,migration and invasion abilities were promoted simultaneously;cell apoptosis was inhibited associated with upregulation of survivin and bcl-2.4.After Beclin1 was silenced,the median lethal dose(LD50)of cisplatin to OSCC cells decreased from 0.07 mg/ml to 0.03 mg/ml,and mortality increased significantly with the reduced expression of multidrug resistance 1(MDR1).Conclusion:1.Autophagy related proteins(Beclinl,mTOR,MAP1LC3B)and apoptosis related proteins(bcl-2,survivin,bax)are involved in oral carcinogenesis,and are associated with invasion and metastasis of oral cancer.2.Beclinl silencing indicates that Beclinl plays important roles as a tumor suppressor by inhibiting proliferation,migration,and invasion;and promoting apoptosis of OSCC cells.Furthermore,Beclin 1 may take effect in evasion of the killing effect of chemotherapeutic drugs by promoting autophagosomes.So,autophagy may be reduced properly to enhance chemosensitivity of OSCC cells to cisplatin. |
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