The amplification of the distal portion of chromosome 3q in lung cancer is a major signature of neoplastic transformation, particularly in the squamous cell carcinoma (SCC) of the lung. A number of potential drivers in the 3q amplicon have been identified and are proposed to contribute to the development of lung SCC. miRNAs have emerged as a new class of small, non-coding RNAs that regulate gene expression and might act as integral parts of the molecular architecture of oncogene and tumor suppressor networks in human cancer, including non-small cell lung cancer (NSCLC). miR 1224-5p, 1248 and 944 are located at 3q amplicon and overexpressed in 50%, 26% and 53% of 30 primary SCCs when compared to normal tissues. The overexpression of these miRNAs was further validated in 237 TCGA lung SCC samples compared with 35 normal tissues (p=0.007, 1.18E-16 and 7.71E-20, respectively). The expression of the three miRNAs was higher in lung SCC compared to lung adenocarcinomas (p=8.19E-05, 1.04E-33 and 3.37E-95, respectively), suggesting unique roles of these miRNAs in the lung SCC development. Using miRNA mRNA target prediction tools (miRANDA and TargetScan) and in the combination with a literature search, we found RUNX1T1 and SMAD4 were candidate tumor suppressor gene target for miRNA-1224-5p and miRNA-1248. Downregulation of RUNX1T1 and SMAD4 were confirmed in TCGA lung SCC dataset. Using real-time RT-PCR, we found that the same three miRNAs 1224-5p, 1248 and 944 are overexpressed in 3q amplified lung SCC cell lines H520 and HCC95. When miRNA inhibitors were used to repress the expression of miR-1224-5p or miR-1248 in H520, we found that RUNX1T1 and SMAD4 protein expression levels were increased, suggesting that these tumor suppressor genes are regulated by miR-1224-5p or miR-1248. Lastly, knockdown of miR-1224-5p or miR-1248 using miRNA inhibitors led to 35-60% growth inhibition in H520 and HCC95 cells. Together, these results indicate potential roles for miR-1245-5p and 1248 in regulating cell proliferation by directly targeting tumor suppressor genes RUNX1T1 or SMAD4 in lung SCC. This work provides, for the first time, evidence for overexpression of miRNAs at the 3q26-29 amplicon that might be implicated in the oncogenesis of lung SCC. The work is supported by the NIH Grant R01 CA102353 to PPM and Lung Cancer Research Foundation grant (2011) to JQ.
Note: This abstract was not presented at the meeting.
Citation Format: Jun Qian, Xiangming Ji, Yong Zou, Megan Hoeksema, Heidi Chen, Pierre P. Massion. Overexpression of chromosome 3q26-29 miRNAs in squamous cell carcinoma of the lung. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 526. doi:10.1158/1538-7445.AM2014-526