Molecular Analysis of the Candidate Tumor Suppressor Gene INGI in Human Head and Neck Tumors With 13q Deletions

• Published in: Genes chromosomes & cancer 2000-03, Vol.27 (3), p.319-322
• Main Authors: Sanchez-Cespedes, M, Okami, K, Cairns, P, Sidransky, D
• Format: Article
• Language: English
• Subjects: chromosome 13; NGI gene
• ISSN: 1045-2257
• DOI: 10.1002/(SICI)1098-2264(200003)27:3<319::AID-GCC13>3.0.CO;2-P

The candidate tumor-suppressor gene INGI encodes p33 super(INGI), a nuclear protein which physically interacts with TP53. It has been shown that p33 super(INGI) acts in the same biochemical pathway as TP53, leading to cell growth inhibition. Interestingly, a rearrangement of the INGI gene was found in a neuroblastoma cell line, supporting its involvement in tumor development. Because INGI resides on the long arm of chromosome 13 (13q34) (a region frequently deleted in many tumor types), we sought to characterize its role in head and neck squamous-cell carcinoma (HNSCC). We first analyzed 44 primary tumors for loss of heterozygosity (LOH) at 13q, using four widely spaced microsatellite markers (13q14, 13q14.3-q22, 13q22, and 13q34). Twenty (48%) of the tumor samples showed LOH in all of the informative markers tested, including D13S1315 at 13q34. Two of the tumors displayed partial losses restricted to one marker (D13S118 at 13q14 in tumor 1164, and D13S135 at 13q14.3-q22 in tumor 1398). We then determined the genomic structure of the INGI gene and sequenced the entire coding region in 20 primary tumors showing 13q LOH and in five head and neck cancer cell lines. A single germline polymorphism was detected in 10 of the tumors analyzed (T to C change) located 110 nucleotides upstream of the starting methionine. No somatic mutations were found in any of the samples, suggesting that INGI is not a tumor suppressor gene target in head and neck cancer.