Expression of p16 protein in acral lentiginous melanoma.
BACKGROUND
Acral lentiginous melanoma (ALM) is a clinicopathologic subtype of cutaneous malignant melanoma. ALM is the most common type of melanoma amongst Asians, Africans, and patients with mixed ancestry. In Brazil, ALM comprises 10% of cutaneous melanoma. ALM develops on palmar, plantar, and subungual skin, and its biology is different from that of other cutaneous melanomas, where sunlight is the major known environmental determinant. Alterations and inactivation of the p16INK4 gene that encodes a specific inhibitor of cyclin-dependent kinase have been related to melanoma genesis and progression. Few studies, however, have addressed p16 expression in ALM.


METHODS
In order to verify and compare p16 protein expression, 32 paraffin-embedded ALM specimens were subjected to a immunohistochemical technique using a monoclonal anti-p16 antibody. The tumors were classified according to thickness (up to 1.0 mm and thicker than 1.0 mm) and the presence of ulceration.


RESULTS
Twenty-five (78%) ALMs displayed positive p16 protein expression: 21 of the 25 (84%) with a thickness of more than 1.0 mm, and four of the seven (57%) with a thickness of 1.0 mm or less. Thirteen of the 17 (76%) nonulcerated lesions and 12 of the 15 (80%) ulcerated lesions displayed positive p16 protein expression.


CONCLUSIONS
The data obtained suggest that p16 protein expression per se may not represent a marker of retinoblastoma protein (pRb) pathway disturbance in ALM tumorigenesis.
Hsieh
Ricardo
R
From the Department of Dermatology, University of São Paulo Medical School, São Paulo, Brazil.
Firmiano
Aline
A
Sotto
Mirian N
MN
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019941:Cyclin-Dependent Kinase Inhibitor p16; D005260:Female; D019942:Genes, p16; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000378:metabolism; D012878:Skin Neoplasms / Q000378:metabolism* / Q000473:pathology
C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins; D016160:Retinoblastoma Protein