Cancer stem cells (CSCs) are epigenetically altered by histone deacetylase (HDAC), resulting in chromatin condensation. We have reported that gefitinib-resistant-persisters (GRP) population within non-small cell lung cancer (NSCLC) cells possesses CSCs features. The purpose of this study is to examine the role of HDAC in the gefitinib-resistant lung CSC.

Accumulating evidence indicates that quiescent cancer stem cells (CSCs) are involved in the resistance to gefitinib in non-small cell lung cancer (NSCLC) as non-mutational mechanism. We have previously reported that gefitinib-resistant persisters (GRPs) highly expressed stemness factors and had characteristic features of the CSCs phenotype. Recent studies demonstrate that FBXW7, a type of F-box protein, plays an important role in the maintenance of quiescent CSC by mediating the degradation of c-Myc protein by ubiquination. The aim of this study is to Fig out the role of FBXW7 in the resistance to gefitinib in NSCLC with EGFR mutation.

Small cell lung cancer (SCLC) is a neuroendocrine tumor which account for 15% of all lung cancers. SCLC is characterized by rapid progression which led metastasis to distant organs and represented poor prognosis. Although there were various molecular targeted therapies in SCLC that were already under investigation, results have been disappointing. The focus on biological pathways has recently shifted from genetic to epigenetic regulations. Histone methylation is one of the epigenetic mechanisms which has pivotal role in gene expression, cell cycle and differentiation. Lysine-specific demethylase 1 (LSD1)/KDM1 is a histone modifier that is expressed in certain human cancers including SCLC. LSD1+8a is one of the isoform of LSD1 that was reported to be restricted in neural tissues and it plays critical role in neuronal differentiation. The aim of this study is to elucidate the epigenetic role of LSD1+8a in SCLC. The expression of LSD1 and LSD1+8a mRNAs were analyzed by qPCR in several cancer cell lines. Neuroendocrine markers were detected by qPCR in several SCLC cell lines. The Pearson correlation test was performed to investigate the correlation between LSD1+8a and neuroendocrine markers. siRNA against specific to exon 8a was designed and knockdown LSD1+8a isoform specifically. Cell proliferation assays following knockdown of LSD1+8a were performed in LSD1+8a expressed SCLC cell lines. LSD1 mRNA was expressed in majority of SCLC cell lines, interestingly LSD1+8a mRNA was detected in small subset of SCLC cell lines. There were positive correlations of LSD1+8a and neuroendocrine marker genes such as chromogranin A (CHGA), enolase2 (ENO2), neural cell adhesion molecule (NCAM) and synaptophysin (SYP) in human cancer cell lines. The suppression of LSD1+8a by siRNA drove to decrease expression of neuroendocrine marker genes in SCLC and inhibited cell proliferation in LSD1+8a expressed cell. LSD1+8a could play an important role in SCLC.