PUB014 Collagen XVII Activates Oct4 and Alters Metabolic Reprogramming through Upregulation of AKT/GSK-3β/β-catenin Pathway in Lung Cancer

Collagen XVII, a type II integral transmembrane protein, is found to be associated with the maintenance of EMT phenotypes and metastasis ability in lung cancer stem cells (CSCs). Pluripotency genes, such as Oct4 and Nanog, constitute the core regulatory network that suppresses differentiation-associated genes, thereby maintaining self-renewal and the pluripotency of the cells. Oct4 can regulate the transcription of the glycolytic enzymes Hk2 and Pkm2, which determine the rate of glycolytic flux in embryonic stem cells. This study aimed to investigate whether Collagen XVII can activate the pluripotent gene expression and subsequently alter the metabolic state of lung CSCs, thus enhancing tumor invasion, chemoresistance and initiation in lung CSC. Several single cell clones of A549 lung cancer cells with overexpression of Collagen XVII were set up to examine the link and possible mechanism among Collagen XVII and pluripotent gene expressions in lung CSCs and investigate if dysregulation of Collagen XVII can cause metabolic reprogramming through activation of Oct4. Extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) are measured using the Seahorse XF24 extracellular flux analyzer. CRISPR/Cas9 system was used for knock-out of Collagen XVII expression in lung cancer cells. We demonstrated that overexpression of Collagen XVII in lung cancer cells increased cancer stemness including migration, invasion, chemoresistance, decreased DNA damage, increased EMT markers and enhanced tumor formation in vivo. Oct4 expression was activated in lung cancer cells with overexpression of Collagen XVII through AKT/GSK-3β/β-catenin pathway. Overexpression of Collagen XVII also increased glycolytic capacity and the lactate level, compared to parental A549 lung cancer cells. The expression of Oct4 was downregulated by knock-out of Collagen XVII, thus resulting in decreased extracellular acidification rate and oxygen consumption rate in lung cancer cells. We found for the first time that Collagen XVII can activate Oct4 through upregulation of AKT/GSK-3β/β-catenin pathway, and thus alter metabolic reprogramming including glycolysis and oxygenation consumption in lung cancer cells. Further investigation to elucidate which metabolism associated proteins is responsible for the stemness of lung cancer stem cells is mandatory.