The novel tumour suppressor gene ING1 is overexpressed in human melanoma cell lines.
BACKGROUND
Epidemiological evidence indicates that exposure to ultraviolet (UV) radiation is directly linked to the increase of both incidence and mortality of melanoma. However, the genetic changes caused by UV radiation that lead to melanoma formation remain poorly understood. Recently, a potential tumour suppressor gene ING1 (inhibitor of growth 1) was shown to inhibit cell growth and induce apoptosis in the presence of p53. We have demonstrated that the expression of ING1 is induced after UV irradiation and that ING1 enhances the repair of UV-damaged DNA.


OBJECTIVE
To investigate if ING1 plays a role in melanoma formation.


METHODS
We examined p33ING1 expression levels in 14 melanoma cell lines.


RESULTS
We found that p33ING1 is overexpressed at both mRNA and protein levels in melanoma cell lines compared with normal melanocytes. Single-strand conformation polymorphism (SSCP) analysis showed band shifting in two melanoma cell lines. DNA sequencing confirmed that there were nucleotide alterations in the ING1 gene in Sk-mel-24 and Sk-mel-110 cell lines. Two silent nucleotide alterations in exon 1a were detected in Sk-mel-110. In Sk-mel-24, the A-->G nucleotide alteration at codon 260 resulted in an amino acid change from Asn to Ser, while seven other nucleotide alterations were silent. To determine if the silent nucleotide alterations in these two melanoma cell lines were due to polymorphism, SSCP analysis of ING1 gene was performed in 25 healthy volunteers. No band shift was observed in the SSCP analysis, suggesting that the nucleotide alterations in the melanoma cell lines are unlikely to be due to polymorphism.


CONCLUSIONS
Taken together, our data demonstrate that ING1 is overexpressed, but infrequently mutated, in melanoma cell lines.
Campos
E I
EI
Department of Medicine, Division of Dermatology, Vancouver Hospital and Health Sciences Centre, University of British Columbia, Vancouver, BC, Canada.
Cheung
K-J J
KJ
Murray
A
A
Li
S
S
Li
G
G
D018797:Cell Cycle Proteins; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics; D004268:DNA-Binding Proteins; D016147:Genes, Tumor Suppressor; D006801:Humans; D000076023:Inhibitor of Growth Protein 1; D047908:Intracellular Signaling Peptides and Proteins; D008544:Melanocytes / Q000378:metabolism; D008545:Melanoma / Q000235:genetics / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins; D011110:Polymorphism, Genetic; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
D018797:Cell Cycle Proteins; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; C501503:ING1 protein, human; D000076023:Inhibitor of Growth Protein 1; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011506:Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D025521:Tumor Suppressor Proteins