P3.01-062 Profiling DNA Methylation and Gene Expression on Cancer Stemness Reprogramming in Lung Adenocarcinoma: Topic: Stem Cells in Lung Cancer

Abstract

The cancer stemness niche that could promote and induce the reprogramming of cancer stem cells (CSCs), is considered as one of the key factors in cancer metastasis, tumor recurrence and drug resistance. The behavior of this specific tumorous microenvironment may correlate with poor prognosis of the disease. However, the contribution of the cancer stemness niche on regulating the differentiation or de-differentiation of CSCs remains unclear. To investigate the mystery of the niche and to discover the genetic and epigenetic machineries along the reprogramming process; here, using the lung CSC/stromal cells co-culture model, integrating with both genome-wide transcriptome and DNA methylome, the gene expression and DNA methylation patterns were analyzed in lung CSCs and the differentiated clones. We found that the stromal cells-incubated lung CSCs (StriCLS1) were significantly characterized as the CSC enriched population; with highly expressed stemness makers, nanog, oct3/4, sox2, and klf4, and showed relatively higher percentages of side population, ALDH activity and tumorigeniety than differentiated cells in both in vitro tumor sphere forming ability and in vivo xenograft model (only 10 StriCLS1 cells could generate tumor formation in NSG mice). We found that these stemness characteristics diminished as removing the feeder stroma cells and could be restored after re-co-culture with the tumorous stroma cells. Although the whole exon-seq data showed the comparability of StriCLS1 and differentiated CLS1 CSCs on the DNA sequences; the gene expression and DNA methylation patterns revealed significantly changes. The results showed that stemness and its reprogramming were related to paracrine/autocrine networks (IGFBPs, WNTs/Hedgehog, HGF/Met, LIF/LIFR), metabolism shift (PDKs and LDHs), and other drug-resistance or stress-response signaling (ABCG2 and AKTs), indicating that these key factors were regulated via the niche which may be affected by the DNA methylation patterning. We conclude that the cancer stemness reprogramming is a well-regulatory process via the paracrine/autocrine connective networks in the tumor microenvironment. This process may contribute to cancer progression, and assist the tumor growth and evolution under different stresses. This study provides new insight into the importance of crosstalk between CSCs and the cancerous microenvironment that could be targeted as potential genetic/epigenetic signaling regulators for anticancer therapy.