Department of Histology and Embryology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China.
Curr Med Chem. 2013;20(16):2145-54. doi: 10.2174/0929867311320160007.
We found a novel marine drug, SZ-685C, that was isolated from the secondary metabolites of a mangrove endophytic fungus (No. 1403) collected from the South China Sea, which has been reported to inhibit the proliferation of certain tumor cells. However, its anticancer mechanism remains unknown. The aims of this study were to observe the effectiveness of SZ-685C on pituitary adenoma cells and determine the underlying mechanisms of action.
A rat prolactinoma cell line, MMQ, was used in this study. A dose escalation of SZ-685C was performed on this cell line, and cell viability was assessed using an MTT assay. Hoechst 33342, Annexin V-FITC/PI, TUNEL staining and flow cytometry were used to evaluate the extent of apoptosis at each concentration of SZ-685C. The effect of SZ-685C on prolactin expression was also evaluated using RT-PCR and immunoblotting. Quantitative RT-PCR was used to detect the expression of miR-200c in SZ-685C-stimulated MMQ cells and pituitary adenoma tissues. This miRNA was then overexpressed in MMQ cells via transfection of a miR-200c mimic to identify the mechanism underling the anti-tumor effect of SZ-685C.
SZ-685C inhibited MMQ cell growth in a dose-dependent manner but showed little toxicity toward rat pituitary cells (RPCs). The IC50s of SZ-685C in MMQ cells and RPCs were 13.2 ± 1.3 mM and 49.1 ± 11.5 mM, respectively, which was statistically significant. Increasing numbers of apoptotic cells were observed in response to escalating concentrations of SZ-685C, and the expression level of prolactin (PRL) was inhibited. Nevertheless, the level of PRL mRNA was unchanged. Additionally, miR-200c was upregulated in MMQ cells compared with RPCs, and downregulation of miR- 200c was observed in SZ-685C-treated MMQ cells. Furthermore, the overexpression of miR-200c weakened the effect of SZ-685C-induced apoptosis of MMQ cells.
Our results suggest that SZ-685C induces MMQ cell apoptosis in a miR-200c-dependent manner. Therefore, SZ-685C might be a useful alternative treatment for pituitary adenoma.
我们从南海采集的一株红树林内生真菌（No. 1403）的次级代谢产物中发现了一种新型海洋药物 SZ-685C，它已被报道能抑制某些肿瘤细胞的增殖。然而，其抗癌机制尚不清楚。本研究旨在观察 SZ-685C 对垂体腺瘤细胞的作用，并确定其作用机制。
本研究采用大鼠泌乳素瘤细胞系 MMQ。对该细胞系进行 SZ-685C 剂量递增，用 MTT 法评估细胞活力。用 Hoechst 33342、Annexin V-FITC/PI、TUNEL 染色和流式细胞术检测各浓度 SZ-685C 诱导的细胞凋亡程度。还通过 RT-PCR 和免疫印迹法评估 SZ-685C 对泌乳素表达的影响。用定量 RT-PCR 检测 SZ-685C 刺激的 MMQ 细胞和垂体腺瘤组织中 miR-200c 的表达。通过转染 miR-200c 模拟物使 MMQ 细胞过表达该 miRNA，以确定 SZ-685C 抗肿瘤作用的机制。
SZ-685C 呈剂量依赖性抑制 MMQ 细胞生长，但对大鼠垂体细胞（RPCs）几乎没有毒性。SZ-685C 在 MMQ 细胞和 RPCs 中的 IC50 分别为 13.2±1.3mM 和 49.1±11.5mM，差异有统计学意义。随着 SZ-685C 浓度的增加，凋亡细胞的数量逐渐增加，催乳素（PRL）的表达受到抑制。然而，PRL mRNA 的水平没有变化。此外，MMQ 细胞中 miR-200c 的表达水平高于 RPCs，而 SZ-685C 处理的 MMQ 细胞中 miR-200c 的表达水平下调。此外，miR-200c 的过表达削弱了 SZ-685C 诱导的 MMQ 细胞凋亡的作用。
我们的结果表明，SZ-685C 通过 miR-200c 依赖性方式诱导 MMQ 细胞凋亡。因此，SZ-685C 可能是治疗垂体腺瘤的一种有用的替代方法。
