Malagobadan Sharan, Ho Chai San, Nagoor Noor Hasima
Institute of Biological Sciences (Genetics & Molecular Biology), Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia.
Center for Research in Biotechnology for Agriculture (CEBAR), University of Malaya, Kuala Lumpur 50603, Malaysia.
Cancer Biol Med. 2020 Feb 15;17(1):101-111. doi: 10.20892/j.issn.2095-3941.2019.0010.
Anoikis is apoptosis that is induced when cells detach from the extracellular matrix and neighboring cells. As anoikis serves as a regulatory barrier, cancer cells often acquire resistance towards anoikis during tumorigenesis to become metastatic. MicroRNAs (miRNAs) are short strand RNA molecules that regulate genes post-transcriptionally by binding to mRNAs and reducing the expression of its target genes. This study aimed to elucidate the role of a novel miRNA, miR-6744-5p, in regulating anoikis in breast cancer and identify its target gene. An anoikis resistant variant of the luminal A type breast cancer MCF-7 cell line (MCF-7-AR) was generated by selecting and amplifying surviving cells after repeated exposure to growth in suspension. MiRNA microarray analysis identified a list of dysregulated miRNAs from which miR-6744-5p was chosen for overexpression and knockdown studies in MCF-7. Additionally, the miRNA was also overexpressed in a triple-negative breast cancer cell line, MDA-MB-231, to evaluate its ability to impair the metastatic potential of breast cancer cells. This study showed that overexpression and knockdown of miR-6744-5p in MCF-7 increased and decreased anoikis sensitivity, respectively. Similarly, overexpression of miR-6744-5p in MDA-MB-231 increased anoikis and also decreased tumor cell invasion and . Furthermore, NAT1 enzyme was identified and validated as the direct target of miR-6744-5p. This study has proven the ability of miR-6744-5p to increase anoikis sensitivity in both luminal A and triple negative breast cancer cell lines, highlighting its therapeutic potential in treating breast cancer.
失巢凋亡是细胞从细胞外基质和邻近细胞脱离时所诱导的细胞凋亡。由于失巢凋亡起着调节屏障的作用，癌细胞在肿瘤发生过程中常常获得对失巢凋亡的抗性从而发生转移。微小RNA（miRNA）是短链RNA分子，通过与信使核糖核酸（mRNA）结合并降低其靶基因的表达来进行转录后基因调控。本研究旨在阐明一种新型miRNA，即miR-6744-5p在调节乳腺癌失巢凋亡中的作用，并确定其靶基因。通过反复使管腔A型乳腺癌MCF-7细胞系（MCF-7-AR）在悬浮培养中生长后选择并扩增存活细胞，生成了一种对失巢凋亡具有抗性的变体。miRNA微阵列分析确定了一系列失调的miRNA，从中选择miR-6744-5p在MCF-7中进行过表达和敲低研究。此外，该miRNA也在三阴性乳腺癌细胞系MDA-MB-231中过表达，以评估其削弱乳腺癌细胞转移潜能的能力。本研究表明，在MCF-7中miR-6744-5p的过表达和敲低分别增加和降低了失巢凋亡敏感性。同样，在MDA-MB-231中miR-6744-5p的过表达增加了失巢凋亡，并且还降低了肿瘤细胞的侵袭。此外，N-乙酰转移酶1（NAT1）酶被鉴定并验证为miR-6744-5p的直接靶标。本研究证明了miR-6744-5p在管腔A型和三阴性乳腺癌细胞系中均具有增加失巢凋亡敏感性的能力，突出了其在治疗乳腺癌方面的治疗潜力。
