Run Lin, Wang Liping, Nong Xiting, Li Nan, Huang Xin, Xiao Yang
Department of Endocrinology, Xi'an Central Hospital, Xi'an JiaoTong University, Xi'an, 710003, Shannxi, PR China.
Department of General Surgery, Xi'an Central Hospital, Xi'an JiaoTong University, Xi'an, 710003, Shannxi, PR China.
Endocrine. 2021 Feb;71(2):418-426. doi: 10.1007/s12020-020-02417-y. Epub 2020 Jul 14.
Thyroid carcinoma is the most frequent endocrine malignancy with high occurrence of BRAFV600E mutations. Though targeted therapy by vemurafenib, a specific inhibitor for BRAFV600E, has achieved great advance in therapeutic landscape, resistance occurrence is still a clinical challenge. Here, we sought to elucidate the function of high mobility group box 1 (HMGB1) in vemurafenib resistance in thyroid cancer harboring BRAF mutation.
The expression of HMGB1 in BRAF-mutant BCPAP and BRAF-wild CAL-62 cells were determined by qRT-PCR and western. Then, BCPAP cells were transfected with recombinant HMGB1 plasmids, and vemurafenib-resistant BCPAP-R cells were treated with si-HMGB1. The efficacy of HMGB1 on vemurafenib resistance was evaluated by detecting cell viability, apoptosis, and caspase-3 activity. In addition, the involvement of autophagy pathway was investigated.
Lower expression of HMGB1 was observed in BRAF-mutant BCPAP cells that had high sensitivity to vemurafenib. Overexpression of HMGB1 attenuated BCPAP cell sensitivity to vemurafenib by increasing cell viability and decreasing cell apoptosis and caspase-3 activity. Intriguingly, higher expression of HMGB1 was confirmed in vemurafenib-resistant BCPAP-R cells. Moreover, knockdown of HMGB1 sensitized BCPAP-R cells to vemurafenib resistance. Mechanistically, vemurafenib exposure induced autophagy by enhancing LC3II, Beclin-1 expression, and reducing autophagy substrate p62 expression. Importantly, targeting HMGB1 suppressed vemurafenib-induced autophagy. Blocking autophagy pathway with its inhibitor 3-MA offset BCPAP-R cell resistance to vemurafenib.
These findings highlight that HMGB1-mediated autophagy may account for vemurafenib resistance in thyroid cancer harboring BRAF mutation, implying a promising approach to overcome vemurafenib resistance in vemurafenib-mutant thyroid carcinomas.
甲状腺癌是最常见的内分泌恶性肿瘤，BRAFV600E突变发生率高。尽管针对BRAFV600E的特异性抑制剂维莫非尼进行的靶向治疗在治疗领域取得了巨大进展，但耐药性的出现仍然是一个临床挑战。在此，我们试图阐明高迁移率族蛋白B1（HMGB1）在携带BRAF突变的甲状腺癌对维莫非尼耐药中的作用。
通过qRT-PCR和western检测BRAF突变的BCPAP细胞和BRAF野生型CAL-62细胞中HMGB1的表达。然后，用重组HMGB1质粒转染BCPAP细胞，并用si-HMGB1处理对维莫非尼耐药的BCPAP-R细胞。通过检测细胞活力、凋亡和caspase-3活性来评估HMGB1对维莫非尼耐药性的影响。此外，还研究了自噬途径的参与情况。
在对维莫非尼高度敏感的BRAF突变BCPAP细胞中观察到HMGB1表达较低。HMGB1的过表达通过增加细胞活力、降低细胞凋亡和caspase-3活性，减弱了BCPAP细胞对维莫非尼的敏感性。有趣的是，在对维莫非尼耐药的BCPAP-R细胞中证实了HMGB1的高表达。此外，敲低HMGB1使BCPAP-R细胞对维莫非尼耐药性敏感。机制上，维莫非尼暴露通过增强LC3II、Beclin-1表达和降低自噬底物p62表达诱导自噬。重要的是，靶向HMGB1抑制了维莫非尼诱导的自噬。用其抑制剂3-MA阻断自噬途径可抵消BCPAP-R细胞对维莫非尼的耐药性。
这些发现突出表明，HMGB1介导的自噬可能是携带BRAF突变的甲状腺癌对维莫非尼耐药的原因，这意味着在BRAF突变的甲状腺癌中克服维莫非尼耐药有了一种有前景的方法。
