Wadhwa Bhumika, Paddar Masroor, Khan Sameer, Mir Sameer, A Clarke Philip, Grabowska Anna M, Vijay Devanahalli G, Malik Fayaz
Academy of Scientific and Innovative Research (AcSIR), New Delhi 110001, India.
Cancer Pharmacology Division, CSIR-Indian Institute of Integrative Medicine, Srinagar 190005, India.
Oncotarget. 2020 Nov 10;11(45):4178-4194. doi: 10.18632/oncotarget.27746.
AKT, a serine threonine kinase, exists in three different isoforms and is known for regulating several biological processes including tumorigenesis. In this study, we investigated the expression and net effect of the individual isoforms in triple negative breast cancers and response to cisplatin treatment using cellular, mice models and clinical samples. Interestingly, analysis of the expressions of AKT isoforms in clinical samples showed relatively higher expression of AKT1 in primary tissues; whereas lung and liver metastatic samples showed elevated expression of AKT2. Similarly, triple-negative breast cancer cell lines, BT-549 and MDA-MB-231, with high proliferative and invasive properties, displayed higher expression levels of AKT1/2. By modulating AKT isoform expression in MCF-10A and BT-549 cell lines, we found that presence of AKT2 was associated with invasiveness, stemness and sensitivity to drug treatment. It was observed that the silencing of AKT2 suppressed the cancer stem cell populations (CD44 CD24, ALDH1), mammosphere formation, invasive and migratory potential in MCF-10A and BT-549 cells. It was further demonstrated that loss of function of AKT1 isoform is associated with reduced sensitivity towards cisplatin treatment in triple-negative breast cancers cellular and syngeneic mice models. The decrease in cisplatin treatment response in shAKT1 cells was allied with the upregulation in the expression of transporter protein ABCG2, whereas silencing of ABCG2 restored cisplatin sensitivity in these cells through AKT/SNAIL/ABCG2 axis. In conclusion, our study demonstrated the varied expression of AKT isoforms in triple-negative breast cancers and also confirmed differential role of isoforms in stemness, invasiveness and response towards the cisplatin treatment.
AKT是一种丝氨酸苏氨酸激酶，以三种不同的亚型存在，并且因调节包括肿瘤发生在内的多种生物学过程而闻名。在本研究中，我们使用细胞、小鼠模型和临床样本，研究了三阴性乳腺癌中各个亚型的表达及净效应，以及对顺铂治疗的反应。有趣的是，对临床样本中AKT亚型表达的分析显示，原发组织中AKT1表达相对较高；而肺和肝转移样本中AKT2表达升高。同样，具有高增殖和侵袭特性的三阴性乳腺癌细胞系BT-549和MDA-MB-231，显示出较高水平的AKT1/2表达。通过调节MCF-10A和BT-549细胞系中AKT亚型的表达，我们发现AKT2的存在与侵袭性、干性及对药物治疗的敏感性相关。据观察，AKT2的沉默抑制了MCF-10A和BT-549细胞中的癌症干细胞群体（CD44 CD24、醛脱氢酶1）、乳腺球形成、侵袭和迁移潜力。进一步证明，在三阴性乳腺癌细胞和同基因小鼠模型中，AKT1亚型功能的丧失与对顺铂治疗的敏感性降低有关。shAKT1细胞中顺铂治疗反应的降低与转运蛋白ABCG2表达的上调有关，而ABCG2的沉默通过AKT/蜗牛/ABCG2轴恢复了这些细胞中的顺铂敏感性。总之，我们的研究证明了三阴性乳腺癌中AKT亚型的不同表达，也证实了亚型在干性、侵袭性和对顺铂治疗反应方面的不同作用。
