Dysregulated microRNAs Enhance ZNF322A Expression and Transcriptional Activity in Lung Cancer

Abstract

Background: ZNF322A is an oncogenic zinc-finger transcription factor which dysregulates genes in control of cell growth and cell motility such as cyclin D1 (CCND1) p53 and alpha-adducin (ADD1) Our published reports show that overexpression of ZNF322A mRNA and protein is found in about 70% of Asian and Caucasian lung cancer patients In addition ZNF322A protein degradation is regulated in part by the CK1δ/GSK3?/FBXW7? axis However the mechanism involved in homeostasis of ZNF322A mRNA remains unclear Purpose: This study aims to investigate the microRNAs regulation on ZNF322A transcription in lung cancer cell and xenograft models In addition we explore the relationship between ZNF322A and its upstream miRNA regulators using clinical studies Results: The 3′UTR of ZNF322A contained target sites for microRNAs miR-98-5p miR-135a-5p miR-326 and miR-484 according to three prediction software or database To validate the reciprocal transcription regulation of microRNA candidates on ZNF322A mRNA expression multiple lung cancer cells were transfected with these indicated miRNAs mimics We constructed 3′UTR luciferase reporter assay for all four miRNA candidates Among them miR-326 and miR-484 inhibited the ZNF322A wild-type 3′UTR luciferase activity but the 3′UTR luciferase activity with the mutated seed regions of the corresponding microRNAs had no response to miR-326 or miR-484 Furthermore expression of both ZNF322A mRNA and protein was attenuated by overexpressing of miR-326 mimics but miR-484 inhibited ZNF322A expression only at the mRNA level not protein level Importantly miR-326 suppressed proliferation and migration ability through inhibition of expression of ZNF322A and its downstream target genes CCND1 and ADD1 in lung cancer cells Reconstitution experiments indicated that miR-326/ZNF322A/CCND1 was important for cell growth regulation while miR-326/ZNF322A/ADD1 was important for cell motility Clinically a trend of inverse correlation between miR-326 and ZNF322A mRNA expression was observed in lung cancer patients Moreover low ZNF322A/ high miR-326 (ZNF322A-L/miR326-H) profile showed better overall survival Conclusions: Our results reveal that miR-326/ZNF322A axis inhibits lung cancer progression by reducing CCND1 and ADD1 expression Furthermore our clinical studies suggest that low ZNF322A/ high miR-326 (ZNF322A-L/miR326-H) profile may be a potential prognosis biomarker for clinical application in the future

Date of Award	2019
Original language	English
Supervisor	Yi-Ching Wang (Supervisor)