Saluja Tajindra Singh, Kumar Vijay, Agrawal Monika, Tripathi Abhilasha, Meher Rajesh Kumar, Srivastava Kamini, Gupta Anurag, Singh Anjana, Chaturvedi Arun, Singh Satyendra Kumar
Stem Cell/Cell Culture Unit, Center for Advance Research, King George's Medical University, Lucknow, Uttar Pradesh, India.
Department of Surgical Oncology, King George's Medical University, Lucknow, Uttar Pradesh, India.
Cancer Manag Res. 2020 Jun 15;12:4519-4530. doi: 10.2147/CMAR.S252292. eCollection 2020.
Despite improved therapeutics in oral squamous cell carcinoma (OSCC), tumor cells that are either quiescent and/or endowed with stem cell-like attributes usually survive treatment and recreate tumor load at relapse. Through this study, we aimed strategically to eliminate these stem cell-like cancer cells using a combination drug approach.
Primary cultures from 15 well-moderately differentiated OSCC were established, and the existence of cancer cells with stem cell-like characteristics using five cancer stem cell (CSC) specific markers - CD44, CD133, CD147, C166, SOX2 and spheroid assay was ascertained. Next, we assessed quiescence in CSCs under normal and growth factor-deprived conditions using Ki67. Among several gene signatures regulating quiescent cellular state, we evaluated the effect of inhibiting Dyrk1b in combination with topoisomerase II and histone deacetylase inhibitors in targeting quiescent CSCs. Multiple drug-effect analysis was carried out with CompuSyn software to determine combination-index values.
We observed that CD44CD133 showed the highest level of SOX2 expression. CSCs showed varying degrees of quiescence, and inhibition of Dyrk1b decreased quiescence and sensitized CSCs to apoptosis. In the drug-combination study, Dyrk1b inhibitor was combined with topoisomerase II and histone deacetylase inhibitors to target quiescent CSCs. In combination, a synergistic effect was seen even at a 16-fold lower dose than IC. Furthermore, combined treatment decreased glutathione levels and increased ROS and mitochondrial stress, leading to increased DNA damage and cytochrome c in CSCs.
We report marker-based identification of CSC subpopulations and synergy of Dyrk1b inhibitor with topoisomerase II and HDAC inhibitors in primary OSCC. The results provide a new therapeutic strategy to minimize quiescence and target oral CSCs simultaneously.
尽管口腔鳞状细胞癌（OSCC）的治疗方法有所改进，但处于静止状态和/或具有干细胞样特性的肿瘤细胞通常能在治疗后存活，并在复发时重新形成肿瘤负荷。通过本研究，我们旨在采用联合用药方法战略性地消除这些干细胞样癌细胞。
建立了15例中分化OSCC的原代培养物，使用五种癌症干细胞（CSC）特异性标志物——CD44、CD133、CD147、C166、SOX2以及球体形成试验确定具有干细胞样特征的癌细胞的存在。接下来，我们使用Ki67评估正常和生长因子剥夺条件下CSC的静止状态。在调节静止细胞状态的多个基因特征中，我们评估了抑制双重特异性酪氨酸磷酸化调节激酶1b（Dyrk1b）与拓扑异构酶II和组蛋白去乙酰化酶抑制剂联合作用于静止CSC的效果。使用CompuSyn软件进行多药效应分析以确定联合指数值。
我们观察到CD44CD133显示出最高水平的SOX2表达。CSC表现出不同程度的静止状态，抑制Dyrk1b可降低静止状态并使CSC对凋亡敏感。在药物联合研究中，Dyrk1b抑制剂与拓扑异构酶II和组蛋白去乙酰化酶抑制剂联合作用于静止CSC。联合使用时，即使剂量比半数抑制浓度（IC）低16倍也能观察到协同效应。此外，联合治疗降低了谷胱甘肽水平，增加了活性氧（ROS）和线粒体应激，导致CSC中的DNA损伤和细胞色素c增加。
我们报告了基于标志物的OSCC原代培养物中CSC亚群的鉴定以及Dyrk1b抑制剂与拓扑异构酶II和组蛋白去乙酰化酶抑制剂的协同作用。这些结果提供了一种新的治疗策略，可同时最大限度地减少静止状态并靶向口腔CSC。
