Aim: To determine the mechanisms of HEATR1 on cell survival in non-small cell lung cancer (NSCLC).
Methods: HEATR1 mRNA expression levels in 57 pairs of NSCLC tumor and adjacent normal lung tissues were analyzed using the TCGA database. The effect of HEATR1 inhibition on cell proliferation, apoptosis, and colony formation was measured in A549 and NCI-H460 cells lines. In addition, the effect of HEATR1 inhibition on tumor growth was measured using in vivo xenograft nude mouse models. Additionally, downstream signaling pathways affected by HEATR1 inhibition were analyzed using microarrays and bioinformatics analysis, and were validated using quantitative real-time polymerase chain reaction and Western blot analysis.
Results: HEATR1 levels were significantly higher in NSCLC tumor tissues compared to normal adjacent lung tissues (P <0.001). In vitro, cell proliferation was significantly reduced in both A549 and NCI-H1299 cells transduced with shHEATR1 compared to shCtrl (P <0.001). Colony formation was also significantly reduced after HEATR1 interference (P <0.01). Additionally, the percentage of apoptosis was significantly increased in cells transduced with shHEATR1 (P <0.001). In vivo, HEATR1 inhibition significantly reduced xenograft tumor growth in nude mice. HEATR1 inhibition drastically affected the p53-signaling pathway, significantly up-regulating PUMA and BAX both at the mRNA and protein levels (P <0.001), while BCL2 levels were significantly down-regulated (P <0.01). The cell proliferation and apoptosis were recovered in cell transduced with shHEATR1 and shp53 compared to shHEATR1 (P <0.05).
Conclusion: HEATR1 inhibition activated p53 by reducing ribosome biogenesis, which subsequently led to NSCLC cell apoptosis and reduced cell survival through the p53-PUMA-BAX/BCL2 axis. Our results provide a mechanism by which therapeutic modulation of HEATR1 could be a treatment strategy for NSCLC. In addition, HEATR1 could be used as a potential biomarker for the prognosis or therapeutic evaluation of NSCLC.
Keywords: HEATR1, non-small cell lung cancer, p53, PUMA, cell survival