We conclude that expressed somatic mutations in infrequently mutated genes beyond the well-characterized ones (e.g., <i>BRAF, RAS, CDKN2A, PTEN, TP53</i>), such as <i>RAC1</i> and <i>SPEN</i>, may have prognostic significance in MM.
The gene for the INK4 family Cdk inhibitor p15 (INK4B) is frequently deleted or inactivated in multiple types of human cancers, indicating that p15 is a tumor suppressor. p15RS is a ubiquitously expressed nuclear protein that is positively regulated by p15 and, in turn, inhibits the expression of cyclin D and cyclin E. To determine whether p15RS has malignancy inhibitory functions in addition to its inhibitory effects on cell cycle entry, we ectopically expressed p15RS in metastatic melanoma A375 cells, in which p15 gene is deleted and p15RS expression is dramatically downregulated, and examined the effect on various malignant phenotypes.
Prospectively acquired tumors from 30 patients who subsequently underwent ILI with melphalan and actinomycin-D for metastatic melanoma were investigated for mRNA expression levels of p14(ARF), p16(INK4a), and MITFm.
In order to clarify the importance of p16 alterations in melanoma, we examined the deletions of p16INK4a and expression of p16 protein in eight unselected primary and metastatic melanoma cell lines from human skin melanomas.
The previously described Met53IleCDKN2A mutation located in exon 2 was detected in a female patient with melanoma metastatic to the regional lymph nodes, multiple primary cutaneous lesions, atypical naevi and a first-degree relative with melanoma.
In summary, we demonstrated a significant inverse correlation between p14ARF protein expression and progression of melanocytic tumors since the amount of p14ARF protein staining decreased from benign melanocytic nevi to metastatic melanoma in situ.