LncRNA FAM83H-AS1 promotes the malignant progression of pancreatic ductal adenocarcinoma by stabilizing FAM83H mRNA to protect β-catenin from degradation

Pancreatic ductal adenocarcinoma is prone to metastasis, resulting in short survival and low quality of life. LncRNAs are pivotal orchestrators that participate in various tumor progress. The underlying role and mechanism of lncRNA FAM83H-AS1 is still unknown in PDAC progression. To address this issue, firstly, we profiled and analyzed the aberrant lncRNA expression in TCGA database and identified FAM83H-AS1 as the most effective one in promoting the migration of pancreatic cancer cells. Then, the expression levels of FAM83H-AS1 in patient's serum, tumor tissues and PDAC cells were detected using RT-qPCR, and FAM83H-AS1 distribution in PDAC cells was determined by performing FISH and RT-qPCR. Next, a series of in vivo and in vitro functional assays were conducted to elucidate the role of FAM83H-AS1 in cell growth and metastasis in PDAC. The regulatory relationship between FAM83H-AS1 and FAM83H (the homologous gene of FAM83H-AS1) was verified by performing protein and RNA degradation assays respectively. Co-IP assays were performed to explore the potential regulatory mechanism of FAM83H to β-catenin. Rescue assays were performed to validate the regulation of the FAM83H-AS1/FAM83H/β-catenin axis in PDAC progression. FAM83H-AS1 was highly expressed in the tumor tissues and serum of patients with PDAC, and was correlated with shorter survival. FAM83H-AS1 significantly promoted the proliferation, invasion and metastasis of PDAC cells, by protecting FAM83H mRNA from degradation. Importantly, FAM83H protein manifested the similar malignant functions as that of FAM83H-AS1 in PDAC cells, and could bind to β-catenin. Specifically, FAM83H could decrease the ubiquitylation of β-catenin, and accordingly activated the effector genes of Wnt/β-catenin signaling. Collectively, FAM83H-AS1 could promote FAM83H expression by stabilizing its mRNA, allowing FAM83H to decrease the ubiquitylation of β-catenin, thus resulted in an amplified FAM83H-AS1/FAM83H/β-catenin signal axis to promote PDAC progression. FAM83H-AS1 might be a novel prognostic and therapeutic target for combating PDAC.