Antisense RNAs Influence Promoter Usage of Their Counterpart Sense Genes in Cancer

Area of Science:

• Molecular Biology
• Cancer Genomics
• Gene Regulation

Background:

• Noncoding natural antisense transcripts (ncNATs) are known regulators of biological processes.
• The role of ncNATs in cancer progression is largely unexplored.
• Hepatocellular carcinoma (HCC) presents a significant unmet need for understanding gene regulation.

Purpose of the Study:

• To identify differentially expressed ncNATs in hepatocellular carcinoma.
• To investigate the functional role of ncNATs in cancer cell growth and gene regulation.
• To elucidate the mechanism of promoter-specific regulation by ncNATs.

Main Methods:

• Differential expression analysis of ncNATs in HCC.
• Functional assays to assess the impact of ncNATs on cell growth.
• RNA sequencing (RNA-seq) to analyze promoter activity and isoform expression.
• Gene silencing experiments.

Main Results:

• Identified a comprehensive list of differentially expressed ncNATs in HCC.
• Discovered a novel ncNAT, HNF4A-AS1L, that suppresses HCC cell growth by regulating the HNF4A gene.
• Demonstrated that HNF4A-AS1L selectively activates the HNF4A P1 promoter, upregulating tumor suppressor isoforms.
• Identified ~100 ncNATs correlating with specific promoter activity across 23 tissue and cancer types.
• Showed that silencing of ncNATs ENSG00000259357 and ENSG00000255031 altered promoter usage of CERS2 and CHKA.

Conclusions:

• ncNATs play a significant role in regulating alternative promoter usage and isoform expression of sense genes.
• Promoter-specific regulation by ncNATs is a key mechanism for context-specific control of gene expression in cancer.
• This study highlights a novel regulatory mechanism with potential implications for cancer therapy.