Search Of The Expression Of P14～(ARF) And FHIT Protein In Thyroid Tumors

[Objective] The INK4a/ARF(alternative reading frame) gene, inactivated in a number of human tumors, is located at 9p21, and encodes two functionally unrelated proteins, p16^INK4a and p14^ARF. p16^INK4a and p14^ARF are transcribed from separate promoters, have unique first exons (El α and El β ) but share exons 2 and 3, are translated from alternative reading frames and bear no amino acid homology.P14^ARF is capable of causing cell cycle arrest in G1 and G2.P14^ARF interacts physically with MDM2 and stabilizes P53 protein in the nucleus by blocking its cytoplasmic transport and MDM2-mediated degradation,so that it may act as an upstream regulator of P53 function.In response to DNA damage, the accumulation of P53 results in cell cycle arrest or apoptosis.Fragile histidine triad gene(FHIT) locates in human chromosome 3pl4.2. It is now known that FHIT spans FRA3B and encodes only a 1.1 kb transcript. The FHIT protein is a hydrolase involved in the cleavage of diadenosine triphosphates.The protein of FHIT has an activity of anti-tumor.For one thing,it can promote the assembly of canaliculus.For another,it can inhibit the cell cycle,promote cell's apoptosis and inhibit the growth of neoplasms.P14^ARF and FHIT are important anti-tumor proteins.They are relative to happenings and developments of several kinds of tumors. But there is rare report about their effects on thyroid tumors.By measuring theexpression of P14ARF and FHIT in thyroid tumor tissues to investigate their functions with development of thyroid tumors. The other purpose of this study is to find new assistant signs to distinguish thyroid follicular carcinoma from adenoma and provide experimental basis for the diagnosis of clinical pathology.[Methods] The expression of P14ARF and FHIT protein in 20 cases of thyroid adenoma and 28 cases of thyroid carcinoma were detected by SP immunohistochemical technique. 28 cases of thyroid carcinoma consist of 11 cases of follicular carcinoma(FTC),12 cases of papillary carcinoma(PTC),4 cases of medullary carcinoma(MTC) and 1 case of undifferentiated carcinoma(UDTC).[Results] Positive rates of P14ARF in thyroid adenomas and carcinomas are 90%n 35.7%. Positive rates of FHIT in thyroid adenomas and carcinomas are 90%n 7.14%.Their expressions are both significant different ( P<0.05 ) between thyroid adenomas and carcinomas. The expressions of P14ARF and FHIT are significant different (P<0.05) between FTC and adenoma,PTC and adenoma. The expression of FHIT is also significant different (i><0.05) between MTC and adenoma. The expressions of P14ARF and FHIT are related to the malignant process of thyroid tumors,but they are not correlated with patients'age> gender and lymph nodes metastasis.Besides,in thyroid tumors,the expression of P14ARF and FHIT are positive related.[Conclusions] The loss of Anti-tumor protein P14ARF and FHIT is one of the important reasons of carcinogenesis of thyroid tumors;Combining immunohistochemical detection of P14ARF and FHIT may do help to distinguish FTC from thyroid adenoma.