Expression of reciprocal hybrid transcripts of HMGIC and FHIT in a pleomorphic adenoma of the parotid gland

The developmentally regulated HMGIC gene, which encodes an architectural transcription factor, has recently been linked to the pathogenesis of benign solid tumors with chromosome aberrations involving 12q13-15. Among these tumors are pleomorphic adenoma of the salivary glands, lipoma, uterine leiomyoma, hamartomas of the breast and lung, fibroadenoma of the breast, angiomyxoma, and endometrial polyps. For most tumor types, however, the translocation partners are variable. At present, no translocation partner genes of HMGIC are known for pleomorphic adenomas. Here, we report that in a primary pleomorphic adenoma of the parotid gland, the FHIT gene, which spans the chromosome 3p14.2 fragile site FRA3B, and is frequently disrupted in tumors, acts as a fusion partner of HMGIC. In addition to normal HMGIC and FHIT transcripts, an HMGIC/FHIT hybrid transcript as well as its reciprocal counterpart, FHIT/HMGIC, were found to be expressed by reverse transcription-PCR. The results establish the concurrent disruption of two tumor-associated genes in a benign tumor.