title: p73 expression is associated with the cellular radiosensitivity in cervical cancer after radiotherapy.
abstract: Apoptosis is one of the causes of cell death in cervical cancer following radiotherapy. By studying the gene expression profile with cDNA apoptotic array, the p73 gene was found overexpressed in radiosensitive cervical cancers when compared with radioresistant ones. To investigate the role of the p73 gene in relation to clinical assessment of radiosensitivity in cervical cancer based on the findings of residual tumor cells in cervical biopsies after completion of radiotherapy, we studied the protein expression of p73 in 59 cervical cancers after radiotherapy and 68 normal cervices using immunohistochemistry. The expression of p73 was found to be significantly increased in cancer samples and, more importantly, in those samples sensitive to radiotherapy (P < 0.001). The overexpression of p73 actually predicted a better prognosis in cervical cancer patients (P < 0.001). To investigate the possible involvement of p73 downstream genes, the protein expressions of p21 and Bax were studied. The expression of p21, but not Bax, was found to be positively correlated with the expression of p73 (P = 0.001). Furthermore, the epigenetic regulation of p73 expression via DNA methylation was also investigated in 103 cervical cancers and 124 normals. Hypermethylation of p73 gene was observed in 38.8% of cervical cancers, and it was significantly associated with reduced or absent p73 expression (P < 0.001). Reactivation of p73 expression in two cervical cancer cell lines by demethylation treatment supported the role of methylation in the regulation of p73 expression. Our findings suggested that p73 expression was related to the radiosensitivity of cervical cancer cells and may play an important role in the regulation of cellular radiosensitivity.
authors.affiliation: Departments of Obstetrics and Gynaecology, Queen Mary Hospital, The University of Hong Kong, Hong Kong, People's Republic of China.
authors.forename: Stephanie Si
authors.initials: SS
authors.lastname: Liu
authors.forename: Rebecca Ching-Yu
authors.initials: RC
authors.lastname: Leung
authors.forename: Kelvin Yuen-Kwong
authors.initials: KY
authors.lastname: Chan
authors.forename: Pui-Man
authors.initials: PM
authors.lastname: Chiu
authors.forename: Annie Nga-Yin
authors.initials: AN
authors.lastname: Cheung
authors.forename: Kar-Fai
authors.initials: KF
authors.lastname: Tam
authors.forename: Tong-Yow
authors.initials: TY
authors.lastname: Ng
authors.forename: Ling-Chui
authors.initials: LC
authors.lastname: Wong
authors.forename: Hextan Yuen-Sheung
authors.initials: HY
authors.lastname: Ngan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002584:Cervix Uteri / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D019175:DNA Methylation; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53; D006367:HeLa Cells; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D011379:Prognosis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012313:RNA / Q000378:metabolism; D011836:Radiation Tolerance / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013447:Sulfites / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D002583:Uterine Cervical Neoplasms / Q000378:metabolism* / Q000532:radiotherapy*; D051028:bcl-2-Associated X Protein; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: C494826:BAX protein, human; D017931:DNA Primers; D018076:DNA, Complementary; D004279:DNA, Viral; D019253:Proto-Oncogene Proteins c-bcl-2; D013447:Sulfites; D051028:bcl-2-Associated X Protein; D012313:RNA; D004247:DNA; D020741:rho GTP-Binding Proteins; C009279:sodium bisulfite