转录因子BCLAF1结合PRDM2调控泌乳素瘤多巴胺D2受体表达的研究

Drug resistance is a difficult problem in the treatment of prolactinoma. The down regulation of dopamine D2 receptor expression is one of the main reasons for drug resistance in prolactinoma. Our preliminary study showed low expression of BCLAF1(bcl2-associated factor 1) in drug resistant prolactinoma patients. In animal study, dopamine D2 receptor was down-regulated in estrogen-induced rat prolactinomas. In addition, BCLAF1 and PRDM2 were found to be down-regulated. In vitro experiment showed that both BCLAF1 and PRDM2 could modulate the expression of dopamine D2 receptor in prolactinoma cells. By means of bioinformatics, the binding sites of BCLAF1 was predicted to be found in the exon region of PRDM2 gene. It seemed that BCLAF1 could directly binding to PRDM2.Therefore, the study hypothesized that BCLAF1 directly binds PRDM2 and regulate the dopamine D2 receptor in prolactinoma.This study aims to validate BCLAF1 transcription factor directly binding PRDM2 in prolactinoma and regulate dopamine D2 receptor coordinately. Therefore we can clarify the mechanisms of drug resistance in prolactinomas and provide new idea for clinical diagnosis and treatment.

药物抵抗是泌乳素瘤临床诊治的难点问题，多巴胺D2受体表达下调是泌乳素瘤发生药物抵抗的最主要原因。本课题组前期研究发现转录因子BCLAF1在人药物抵抗泌乳素瘤中低表达。本课题组通过大剂量雌激素进行泌乳素瘤造模，造模成功后显示多巴胺D2受体表达下降，同时BCALF1和PRDM2也均显著降低。在细胞水平初步研究证实BCLAF1和PRDM2均参与调控多巴胺D2受体表达。利用生物信息学方法预测分析PRDM2基因的外显子区域存在BCLAF1的结合位点，即BCLAF1与PRDM2可以直接结合。基于以上研究基础，本课题提出如下假设：BCLAF1可直接结合PRDM2共同调控泌乳素瘤多巴胺D2受体表达。本课题拟验证BCLAF1直接结合PRDM2及调控泌乳素瘤多巴胺D2受体表达的分子机制，为解决药物抵抗泌乳素瘤的临床实际问题提供新的思路。

药物抵抗是泌乳素瘤临床诊治的难点，多巴胺D2受体表达下调是泌乳素瘤发生药物抵抗的最主要原因之一。本课题主要研究转录因子BCLAF1结合PRDM2调控泌乳素瘤细胞D2受体表达的分子机制，以探索药物抵抗泌乳素瘤的临床治疗新靶点。结果发现PRDM2对D2R蛋白表达无显著调控作用，且对PRL分泌及细胞增殖活力无影响；进一步干扰BCLAF1后可以促进PRL的分泌，但PRDM2及D2R蛋白水平的表达无显著差异，细胞增殖活力无显著差异。进一步汇总分析多个泌乳素瘤芯片筛选差异表达基因，表观修饰调控可作为今后研究方向之一。临床诊治方面，首次报道了国内单中心巨泌乳素血症的发生比例及临床特点；全国范围调查发现目前内分泌科医师在泌乳素瘤的临床实践过程中存在不一致性，需要更多循证依据指导临床诊治。然而泌乳素瘤最重要的临床问题在于严重影响生殖功能，可引起不孕不育，但具体机制尚不清晰。初步探索发现，泌乳素瘤患者血清spexin水平有升高趋势；spexin干预雌性小鼠后可引起动情周期缩短；体内实验初步发现spexin干预后可引起GnRH分布脑区cFOS激活。因此提出假设spexin可能参与高泌乳素血症抑制GnRH释放分泌的机制调控，为揭示中枢性腺功能调控提供新的理论体系。本课题科学意义：积极探索了泌乳素瘤药物抵抗中多巴胺D2受体调控的分子机制，并通过反复实验发现BCLAF1-PRDM2假设通路对D2R表达的影响较小；初步发现spexin可能影响生殖功能，可以作为今后研究高泌乳素血症抑制GnRH释放的潜在靶点之一。