Abstract B15: miR-10a regulation of cancer stem cells in non-small cell lung cancer

The cancer stem cell model hypothesizes that a small subpopulation of a given tumor is endowed with the ability to give rise to the bulk of the tumor mass. The ability to understand signaling pathways that maintain cancer stem cells would provide for novel therapeutic targets. Recent evidence has shown that in non-small cell lung cancer (NSCLC) the stem cell population can be defined by aldehyde dehydrogenase (ALDH) activity, with this fraction of cells demonstrating self-renewal, serial transplantation, resistance to therapy, and increased tumorigenicity. We are interested in studying the involvement of microRNAs in potentially regulating the ALDH+ cancer stem cell population in NSCLC. MicroRNAs have been shown to be critical for the differentiation of several cancer cell types and we hypothesize that they may be critical for the differentiation of lung cancer stem cells into terminally-differentiated, non-dividing cells. miR-10a is a microRNA located in the HOX cluster of genes, which is known to be important for the development of the body plane along the anterior-posterior axis. Additionally, miR-10a has been shown to be induced by all-trans-retinoic acid (ATRA), clinically used to induce differentiation in neuroblastoma and acute promyelocytic leukemia. We treated H2009 NSCLC cells with miR-10a mimic and observed a significant decrease in the ALDH+ cell population. This decrease was related to the loss of mRNA and protein levels of ALDH1A3, an isoform of the ALDH family of proteins. Increasing miR-10a levels inhibited the ability to form colonies and induced apoptosis. We then tested if depletion of ALDH+ cells using miR-10a mimic would affect the response to paclitaxel, which is a front line therapy for NSCLC. We observed a 10-fold decrease in cell viability in the presence of miR-10a mimic, suggesting that high levels of miR-10a may predict for sensitivity to taxane therapy. Assessing miR-10a levels in a clinically annotated database of NSCLC patients demonstrated that high miR-10a levels correlate with longer overall survival. A consensus target prediction search using multiple algorithms showed that ALDH1A3 is not a direct target of miR-10a. A targeted siRNA screen containing genes implicated in stem cell maintenance revealed that the WNT and Notch pathway are important for cell survival. Both pathways are down regulated when cells are treated with miR-10a mimic. TargetScan identify DVL3 as a miR-10a target gene. Manipulation of miR-10a levels res