Biochemistry Program, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, USA.
Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA.
mBio. 2020 Jun 16;11(3):e01190-20. doi: 10.1128/mBio.01190-20.
Tumor cells overcome the cytostatic and cytotoxic restraints of TP53 tumor suppressor signaling through a variety of mechanisms. High-risk human papillomavirus (HPV)-positive tumor cells retain wild-type TP53 because the HPV E6/UBE3A ubiquitin ligase complex targets TP53 for proteasomal degradation. While restoration of TP53 in tumor cells holds great promise for cancer therapy, attempts to functionally restore the dormant TP53 tumor suppressor in HPV-positive cancer cells by inhibiting the HPV E6/UBE3A ubiquitin ligase complex have not yet been successful. The damage-induced long noncoding RNA, DINO (DINOL), is a TP53 transcriptional target that has been reported to bind to and stabilize TP53, thereby amplifying TP53 signaling. We show that HPV-positive cervical carcinoma cells contain low levels of DINO because of HPV E6/UBE3A-mediated TP53 degradation. Acute DINO expression overrides HPV16 E6/UBE3A-mediated TP53 degradation, causing TP53 stabilization and increased expression of TP53 transcriptional target genes. This causes a marked sensitization to chemotherapy agents and renders cells vulnerable to metabolic stress. Acute DINO expression in HPV-positive cervical cancer cells induces hallmarks of DNA damage response signaling, and TP53 activation involves ATM/CHK2 signaling. DINO upregulation in response to DNA damage is independent of ATM/CHK2 and can occur in cancer cells that express mutant TP53. Functional restoration of the TP53 tumor suppressor holds great promise for anticancer therapy. Current strategies are focused on modulating TP53 regulatory proteins. Long noncoding RNAs (lncRNAs) have emerged as important regulators of TP53 as well as modulators of downstream tumor-suppressive transcriptional responses. Unlike many other cancer types, human papillomavirus (HPV)-positive cancer cells retain wild-type TP53 that is rendered dysfunctional by the viral E6 protein. We show that acute expression of the damage-induced long noncoding RNA, DINO, a known TP53 transcriptional target and functional modulator, causes TP53 reactivation in HPV-positive cervical cancer cells. This causes increased vulnerability to standard chemotherapeutics as well as biguanide compounds that cause metabolic stress. Hence, strategies that target DINO may be useful for restoring TP53 tumor suppressor activity in HPV-positive cancers and other tumor types that retain wild-type TP53.
肿瘤细胞通过多种机制克服 TP53 肿瘤抑制信号的细胞周期停滞和细胞毒性限制。高危型人乳头瘤病毒 (HPV) 阳性肿瘤细胞保留野生型 TP53,因为 HPV E6/UBE3A 泛素连接酶复合物将 TP53 靶向蛋白酶体降解。虽然恢复肿瘤细胞中的 TP53 对癌症治疗有很大的希望,但通过抑制 HPV E6/UBE3A 泛素连接酶复合物来功能性地恢复 HPV 阳性癌细胞中休眠的 TP53 肿瘤抑制因子的尝试尚未成功。损伤诱导的长非编码 RNA,DINO(DINOL),是 TP53 的转录靶标,据报道,它可以与 TP53 结合并稳定 TP53,从而放大 TP53 信号。我们表明,由于 HPV E6/UBE3A 介导的 TP53 降解,HPV 阳性宫颈癌细胞中含有低水平的 DINO。急性 DINO 表达会覆盖 HPV16 E6/UBE3A 介导的 TP53 降解,导致 TP53 稳定和 TP53 转录靶基因表达增加。这会导致对化疗药物的显著敏感性,并使细胞容易受到代谢应激的影响。HPV 阳性宫颈癌细胞中急性 DINO 表达诱导 DNA 损伤反应信号的特征,TP53 激活涉及 ATM/CHK2 信号。DNA 损伤反应中 DINO 的上调独立于 ATM/CHK2,并且可以发生在表达突变型 TP53 的癌细胞中。功能性恢复 TP53 肿瘤抑制因子对癌症治疗有很大的希望。目前的策略集中在调节 TP53 调节蛋白上。长非编码 RNA(lncRNA)已成为 TP53 的重要调节剂,也是下游肿瘤抑制转录反应的调节剂。与许多其他癌症类型不同,人乳头瘤病毒 (HPV) 阳性癌症细胞保留野生型 TP53,该型 TP53 被病毒 E6 蛋白失活。我们表明,损伤诱导的长非编码 RNA DINO 的急性表达,一种已知的 TP53 转录靶标和功能调节剂,会导致 HPV 阳性宫颈癌细胞中 TP53 的重新激活。这会导致对标准化疗药物以及引起代谢应激的双胍类化合物的敏感性增加。因此,靶向 DINO 的策略可能有助于恢复 HPV 阳性癌症和其他保留野生型 TP53 的肿瘤类型中 TP53 肿瘤抑制因子的活性。