FHIT GENE ALTERATIONS IN CERVICAL CANCER PATHOGENESIS

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DESCRIPTION: (adapted from the investigator's abstract) Cervical cancer causes significant morbidity and mortality for women throughout the world. Frequent loss of heterozygosity (LOH) of chromosome 3p13-14.3 has been seen in invasive cervical carcinoma and its intraepithelial precursor lesions. Based in part on its localization at 3p14.2, FHIT (for fragile histidine triad) is a candidate 3p tumor suppressor gene in cervical cancer. Somatic mutations in FHIT, including intragenic homozygous deletions and integration of human papillomavirus (HPV) sequences into the FA3B/FHIT fragile site, have been detected in only a few cervical cancers. However, altered FHIT mRNAs and markedly reduced or absent Fhit protein have been found in about 70% of cervical carcinomas, suggesting that FHIT alterations may be frequent and important in cervical cancer. The goals of this proposal are to define the prevalence, nature, and significance of FHIT alterations in cervical cancer, and to determine if Fhit expression is a prognostic marker in cervical cancers and precancers. Four Specific Aims are propose: 1) To characterize Fhit protein expression in precancerous cervical lesions. The role of FHIT inactivation in the progression of intraepithelial neoplasia to carcinoma will be studied using immunohistochemistry to assess Fhit protein expression in normal cervix and precancerous lesions of various grads. The relationship between FHIT LOH and loss of Fhit protein expression will also be examined. 2) To determine if 3p14.2 LOH and loss of Fhit expression are prognostic markers in invasive cervical carcinomas. Chromosome 3p LOH and Fhit protein expression in cancer specimens will be correlated with survival in a large cohort of cervical cancer patients for whom excellent follow-up data are already available. 3) To identify somatic mutations, such as HPV integration and homozygous deletion, in FHIT in cervical carcinomas. Two-color fluorescence in situ hybridization will be used to identify HPV integration in the FRA3B/FHIT locus in primary tumors and cell lines. PCR-based and Southern blot analyses will be used to identify homozygous deletions in FHIT. 4) To demonstrate that FHIT suppresses the tumorigenic properties of cervical cancers. A panel of isogenic cervical cancer cell lines that differ only in Fhit expression will be characterized with in vitro and in vivo assays, including colony formation, growth rate, morphology in monolayer and organotypic raft cultures, apoptosis, anchorage independent growth and tumorigenicity in nude mice. The proposed studies will offer new insights into cervical cancer pathogenesis, and may also identify prognostic markers that improve the clinical management of this disease.