Department of Histology and Embryology, Medical School of Sun Yat-sen University, No. 74, Zhongshan Road 2, Guangzhou, 510080, Guangdong, China.
Department of Neurosurgery and Pituitary Tumor Center, The First Affiliated Hospital of Sun Yat-sen University, No. 58, Zhongshan Road 2, Guangzhou, 510080, Guangdong, China.
J Endocrinol Invest. 2019 Jun;42(6):639-652. doi: 10.1007/s40618-018-0963-4. Epub 2018 Oct 28.
Prolactinoma is the most commonly seen secretory tumor of pituitary glands, which accounts for approximately up to 40% of total pituitary adenomas. Due to its high drug resistance, dopamine agonist, such as bromocriptine, has limited effect on the treatment of patients with prolactinoma. Recent discoveries have revealed that multiple miRNAs were involved in regulating drug resistance. In this research, we explored the relationship between miR-145-5p expression as well as bromocriptine sensitivity both in vitro and in vivo.
To study the role of miR-145-5p in drug resistance of prolactinoma, the expression levels of miR-145-5p in bromocriptine-resistant prolactinoma cell line MMQ/BRC and its parental cell line MMQ cells, 24 bromocriptine-resistant as well as eight sensitive clinical samples were measured by qRT-PCR. Moreover, CCK8, flow cytometry and immunofluorescence were performed to identify the biological characteristics of MMQ/BRC and MMQ. TPT1 was predicted as a direct target gene of miR-145-5p by bioinformatic methods. In addition, qRT-PCR, western blot and immunohistochemistry were used to detect the expression level of TPT1 in clinical specimens and cell lines. Xenograft mouse model was constructed to analyze whether miR-145-5p could reverse bromocriptine resistance in prolactinoma in vivo.
In our study, bromocriptine-resistant prolactinoma clinical samples and cell line had decreased miR-145-5p levels and expressed high levels of TPT1 compared with their sensitive counterparts. Bioinformatic methods and our preliminary dual luciferase reporter assay were utilized to elucidate that TPT1 was a direct target gene of miR-145-5p. Furthermore, introducing miR-145-5p mimic into MMQ cells led to a decrease of IC50 along with upregulation of TPT1; nevertheless, transfecting the corresponding inhibitor into MMQ cells resulted in an upregulation of IC50 as well as reduction of TPT1.
Collectively, our findings elucidated the role of miR-145-5p as an important regulator of drug resistance in prolactinoma by controlling TPT1, and implicated the potential application of miR-145-5p in cancer therapy as well.
催乳素瘤是最常见的垂体分泌性肿瘤，约占垂体腺瘤的 40%。由于其高度耐药性，多巴胺激动剂如溴隐亭对催乳素瘤患者的治疗效果有限。最近的发现表明，多种 miRNA 参与了调节耐药性。在这项研究中，我们探讨了 miR-145-5p 的表达及其在体外和体内对溴隐亭敏感性之间的关系。
为了研究 miR-145-5p 在催乳素瘤耐药中的作用，通过 qRT-PCR 测量了溴隐亭耐药催乳素瘤细胞系 MMQ/BRC 及其亲本细胞系 MMQ 细胞、24 例溴隐亭耐药和 8 例敏感的临床样本中 miR-145-5p 的表达水平。此外，通过 CCK8、流式细胞术和免疫荧光法鉴定 MMQ/BRC 和 MMQ 的生物学特性。通过生物信息学方法预测 TPT1 是 miR-145-5p 的直接靶基因。此外，通过 qRT-PCR、western blot 和免疫组化检测了临床标本和细胞系中 TPT1 的表达水平。构建异种移植小鼠模型以分析 miR-145-5p 是否可以在体内逆转催乳素瘤的溴隐亭耐药性。
在我们的研究中，与敏感对照相比，溴隐亭耐药的催乳素瘤临床样本和细胞系中 miR-145-5p 水平降低，TPT1 表达水平升高。生物信息学方法和我们的初步双荧光素酶报告基因检测证实 TPT1 是 miR-145-5p 的直接靶基因。此外，将 miR-145-5p 模拟物转染到 MMQ 细胞中会导致 IC50 降低，同时 TPT1 上调；然而，将相应的抑制剂转染到 MMQ 细胞中会导致 IC50 上调和 TPT1 减少。
总之，我们的研究结果表明，miR-145-5p 通过控制 TPT1 作为催乳素瘤耐药的重要调节因子发挥作用，并暗示 miR-145-5p 在癌症治疗中的潜在应用。
