Expression of Rb, pRb2/p130, p53, and p16 proteins in malignant melanoma of oral mucosa

We previously reported that pRh2/p130 gene, one of the Rb family members, w as immunohistochemically abundantly expressed in well-differentiated oral s quamous cell carcinomas, whereas in undifferentiated ones the expression wa s low. Oral malignant melanoma is extremely rare, however the prognosis is poor because it tends to locally invade tissue or metastasize and its biolo gical behavior appears to be different from cutaneous malignant melanoma. T he present study dealt with the expression of pRb2/p130, Rb, p53, and p16 i n 13 cases of malignant melanoma of oral mucosa as revealed by immunohistoc hemical staining. The stage classification of the 13 patients was as follow s, stage II: eight patients, stage III: three patients, and stage IV: two p atients. pRb2/ p130 was expressed in only two stage II-cases, neither of wh ich have shown any evidence of recurrence or metastasis for over 14 years. Positive staining for Rb was found in three cases consisting of one stage I I-case, one stage III-case, and one stage IV-case. p53 was expressed in two cases, one a stage II and the other a stage IV. Positive staining for p16 was found in seven cases consisting of four stage II-cases, two stage III-c ases, and one stage IV-case. pRb2/p130 may be inversely correlated with the malignancy of oral malignant melanoma, but further study is needed. (C) 20 01 EIsevier Science Ltd. All rights reserved.