Aberrant expression of p16 and RB protein in eccrine porocarcinoma.
BACKGROUND
Eccrine porocarcinoma is a rare malignant tumor of the sweat gland and very little is known about its etiology and molecular basis.


METHODS
To investigate the expression of p16 and retinoblastoma (RB) protein and their relationship, an immunohistochemical method was performed on nine eccrine porocarcinomas and five eccrine poromas. Furthermore, one case of eccrine porocarcinoma was analyzed for p16 gene mutation.


RESULTS
A striking inverse correlation between p16 and RB expression was noted in all of the eccrine porocarcinomas and poromas. Strong immunoreactivity for p16 protein was observed in both nuclei and cytoplasm of the tumor cells in eight out of nine cases of eccrine porocarcinomas, while RB expression was negative in these cases. Conversely, one case of eccrine porocarcinoma did not show immunoreactivity for p16 protein, whereas RB protein was positive in the scattered nuclei. On the other hand, immunostaining of p16 was negative in all cases of five poromas, whereas RB-positive nuclei were sparse. No p16 gene mutation was detected in the investigated eccrine porocarcinoma case.


CONCLUSIONS
These results indicate that detectable p16 protein and loss of RB protein are common occurrences in eccrine porocarcinoma lesions. Moreover, overexpression of p16 protein may be an additional, simple and useful diagnostic marker for eccrine porocarcinoma on routine laboratory screening.
Department of Dermatology, Gifu University School of Medicine, Gifu, Japan.
Li-Hong
LH
Gu
Yoshiro
Y
Ichiki
Yasuo
Y
Kitajima
D018250:Acrospiroma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000096:biosynthesis*; D005260:Female; D019942:Genes, p16; D006801:Humans; D007150:Immunohistochemistry; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009364:Neoplasm Recurrence, Local; D016160:Retinoblastoma Protein / Q000096:biosynthesis*; D013544:Sweat Gland Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome
D014408:Biomarkers, Tumor; D019941:Cyclin-Dependent Kinase Inhibitor p16; D016160:Retinoblastoma Protein