一个新的rho家族基因与膀胱癌关系的研究

The Rho proteins are a class of small molecular GTPases that regulate multiple fundamental cellular processes by mediating the G-protein-coupled receptor signaling pathway. Rhotekin, which is one of the downstream target molecules of Rho with a Rho binding motif class I domain, can inhibit endogenous or RhoGAP-stimulating Rho GTPase activity to regulate the signaling pathway. A novel human cDNA containing an intact open reading frame that encodes 544 amino acids has been identified. As this putative protein shares 84. 6% amino acid identity with mouse Rhotekin, and has a tandem Rho binding domain class 1 and Pleckstrin homology domain, it was regarded as a human homologue of the mouse Rhotekin and assigned a symbol of RTKN. With the human Rhotekin cDNA as a probe, Northern hybridization revealed that a 4.0-kb transcript was expressed at a high level in prostate and at a middle level in 13 of 16 tissues examined, but it cannot be detected in liver and lung tissues. Meanwhile, a 2.4-kb transcript was expressed at a middle level in prostate and another 3.0-kb transcript in kidney. In addition, the RTKN gene was localized to chromosome 2p13 between markers D2S145 at 6.94 cR (LOD > 12) and D2S286 at 8.12 cR (LOD > 9.7) by radiation hybrid panel mapping. Compared with BAC clone AC005041 sequence, there were 12 exons for the RTKN gene and it spanned a 16.5-kb genomic region. To further investigate the expression of RTKN mRNA in bladder neoplasm. Total RNA was extracted from 33 surgically resected specimens of bladder carcinoma and nomal mucosa. After the optimal reverse transcription polymerase chain reaction (RT-PCR) condition was found, the mRNA expression levels of the RTKN gene in the lesions and normal mucosa were examined semi-quantitatively and the relation between these expression levels and clinical pathological markers was compared. The expression of RTKN gene mRNA in lesion of bladder carcinoma was significantly higher than that in contiguous normal mucosa(P<0.01). The normal range of RTKN/β－MG2 in mRNA expression was 0.162-0.689 . Based on this normal range the 33 patients were divided 3 groups: down－regulated expression (2 cases)、 up-regulated expression group( 22 cases) and high-expression group ( 9 cases). In the overexpression group the lesions of 22 cases in stages and type of pathology Chi-squared test analysis demonstrated a significant difference in both aspect between these two groups (p<0.05).RTKN gene may play an important role in bladder carcinogensis and correlate with invasion and metastasis of bladder carcinoma.

我们采用cDNA候选克隆的方法从人的膀胱癌新鲜组织中，分离到一个全长为2417bp的cDNA，对该cDNA的核酸测序和氨基酸顺序预测显示，它含有与ras癌基因超家族中rho亚基因家族蛋白结合序列的保守区，通过Genbank及EMBL数据库查新检索表明，它是一个人类新的基因，芯扛没蛴氚螂装┑墓叵担螂装┑姆⒉』坪椭瘟铺峁┬碌闹匾南咚鳌