[Clinical significance of mdm2 and p53 expression in orbital rhabdomyosarcoma].
OBJECTIVE
To evaluate the role of oncogene mdm2 and p53 in the development of orbital rhabdomyosarcoma (ORMS) and demonstrate the feasibility of mdm2 and p53 as biological characteristic markers and prognostic indicators.


METHODS
Immunostainings of mdm2, p53 and Ki-67 antigen were performed on archival paraffin-embedded tissues taken from 31 ORMS patients. In situ hybridization was used to demonstrate the expression of mdm2 and p53 on the mRNA level. The correlations between the two genes and the clinical histopathologic parameters including age, gender, cells subtype, differentiation grade and proliferation index were analyzed.


RESULTS
The positive expressions of mdm2 and p53 were 77.4% (24/31) and 71.0% (22/31) respectively; and the co-expression of mdm2 and p53 was 61.3%. The expressions of mdm2 and p53 on the protein level were in coincidence with that on the mRNA level. (1)The poorly and moderately differentiated group showed significantly higher expression of mdm2 and co-expression of mdm2-p53 than the well-differentiated group (P = 0.007; P = 0.009, respectively). (2) The samples were divided into actively-proliferating group and inactively-proliferating group in accordance with the expression of Ki-67 protein. The positive expression of p53 was significantly higher in actively-proliferating group than inactively-proliferating group. No statistic correlation of the positive expression of mdm2 and p53 with the other histopathologic parameters was observed.


CONCLUSIONS
mdm2 and p53 were significantly correlated with the differentiation and proliferation of ORMS. The co-expression of mdm2 and p53 expression suggested that mdm2 might play a role in deactivation of p53. The overexpression of mdm2 and p53 leaded to the loss of cell cycle control and may contribute to the tumorigenesis and tumor progression of ORMS. Mdm2 and p53 may be prognostic indicators of the tumor.
Xu
Xiao-Lin
XL
Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Capital University of Medical Sciences, Beijing 100005, China.
Li
Bin
B
Sun
Xian-Li
XL
Li
Liao-Qing
LQ
D006801:Humans; D019394:Ki-67 Antigen / Q000096:biosynthesis; D009918:Orbital Neoplasms / Q000378:metabolism* / Q000473:pathology; D011379:Prognosis; D051736:Proto-Oncogene Proteins c-mdm2 / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012208:Rhabdomyosarcoma / Q000378:metabolism* / Q000473:pathology; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis* / Q000235:genetics
D019394:Ki-67 Antigen; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2