PRDM2基因在泌乳素腺瘤溴隐亭耐药形成中的作用

Prolactinomas are the most common type of functioning pituitary adenomas and dopamine agonists (DAs) are the first-line drugs of choice to treat them. DAs selectively stimulate the dopamine D2 receptor (D2R) and Gi protein, thus suppressing transcription of prolactin (PRL) and multiplication of normal and prolactinoma cells, leading to reduction of tumor size and serum PRL levels. Bromocriptine (BCR), the only commercially available DA in mainland China, is very effective in normalizing PRL levels and reducing tumor size. However, the tumors in 11%-38% of patients are resistant to BCR. We assume that genetic changes in prolactinomas could probably lead to decrease of D2R and Gi in the process of BCR resistance of prolactinomas. Our previous research has shown the decreased expression of PRDM2 in resistant-BCR prolactinomas by whole-exome sequencing. A report shows lower expression of PRDM2 can lead to decreased expression of Gi protein in esophageal squamous cancer cells. Therefore, we presume that lower levels of PRDM2 may play a role in the process BCR resistance of prolactinomas. There are no reports related with the research at home and abroad. The expression of PRDM2 will be then validated by RT–qPCR, immunohistochemical staining and Western-Blot in the research. The function of PRDM2 in BCR resistance of prolactinomas will be observed by plasmid transfection and RNA interfering technology in MMQ cell. The expression of PRDM2 will be then validated by RT–qPCR in the serum of patients resistant and responsive to bromocrpine. This research will indicate that PRDM2 may play a role in the process of BCR resistance of prolactinomas and will provide experimental and theoretical basis in the personalized treatment of BCR resistance of prolactinomas.

泌乳素腺瘤是最常见的功能性垂体腺瘤，首选多巴胺受体激动剂（溴隐亭）治疗，但仍有11%-38%的患者对药物治疗无效，其耐药可能是因为基因改变导致腺瘤细胞膜多巴胺受体2及其下游Gi蛋白下降、溴隐亭抑制泌乳素腺瘤细胞核内泌乳素基因转录能力下降。前期我们通过基因筛查发现耐药泌乳素腺瘤中PRDM2基因表达下降，文献报道PRDM2蛋白下调可导致食管鳞状细胞癌细胞内Gi蛋白下调，其是否参与泌乳素腺瘤耐药的发生及如何参与未有相关报道。本研究拟对PRDM2基因及蛋白的变化进行进一步验证；并分别通过质粒转染（PRDM2基因增强）和RNA干扰（PRDM2基因沉默）观察大鼠泌乳素腺瘤MMQ细胞系对溴隐亭的反应，检测相应效应蛋白PRDM2、Gi的变化情况，来探讨PRDM2基因在耐药中的作用；同时分别收集20例对溴隐亭敏感和耐药患者的血清、比较PRDM2基因的表达差异，为泌乳素腺瘤患者制定个体化治疗方案提供理论依据。

泌乳素腺瘤是最常见的功能性垂体腺瘤，首选多巴胺受体激动剂药物治疗（溴隐亭为国内唯一上市药物），但仍有11%-38%的患者对药物治疗无效，其耐药可能是因为基因改变导致腺瘤细胞膜多巴胺受体2及其下游Gi蛋白下降、溴隐亭抑制泌乳素腺瘤细胞核内泌乳素基因转录能力下降。我们首先选取6例溴隐亭耐药的泌乳素腺瘤和6例溴隐亭敏感的泌乳素腺瘤进行二代全外显子测序，并通过生物信息学分析发现耐药泌乳素腺瘤中PRDM2基因表达下降，然后，本研究选取12例溴隐亭耐药和溴隐亭敏感的泌乳素腺瘤标本，通过RT–qPCR对PRDM2基因表达量进行验证，结果发现耐药泌乳素腺瘤中PRDM2基因表达量较溴隐亭敏感组下降5倍左右(p < 0.05)。随之，我们通过Western blotting和免疫组化证实溴隐亭耐药组PRDM2蛋白较溴隐亭敏感组更低(p < 0.05)。通过质粒转染使MMQ细胞使其PRDM2基因表达增强发现，MMQ细胞膜上D2受体表达增加，其对溴隐亭敏感性也随之增强(p < 0.05)。 通过RNA干扰MMQ细胞使其PRDM2表达下降，MMQ细胞膜上的D2受体表达下降，其对溴隐亭的敏感性也随之下降(p < 0.05)。最后，项目组分别选取12例溴隐亭耐药和敏感的泌乳素腺瘤患者进行了进行随访和统计学分析，发现PRDM2表达量低的患者更容易形成耐药(p < 0.05)，并且肿瘤更容易复发(p < 0.05)。.本课题将初步揭示PRDM2基因在泌乳素腺瘤溴隐亭耐药形成过程中的作用，为新的临床治疗靶点选择提供实验基础；同时为泌乳素腺瘤患者制定个体化的治疗方案提供理论依据。