A one, two finish of β‐catenin: targeting its activity and synthesis in hepatocellular carcinoma by novel small molecules and antisense peptide‐nucleic acids

Abstract

Hepatocellular Carcinoma (HCC) is the 3rd most common cause of cancer related death throughout the world due to a lack of an effective therapy. There has been increasing evidence that about 30% of all clinically diagnosed HCC cases are a result of mutations in the β‐catenin gene. Several factors are regulated by β‐catenin, which play a role in cell proliferation, migration, angiogenesis, and survival, which can lead to tumor formation. We have developed a small molecule (SM) inhibitor of β‐catenin activity (PMED‐1), as well as a novel, cell permeable, anti‐sense oligonucleotide peptide nucleic acid (PNA) that specifically targets the β‐catenin transcription start site (T1) and inhibits its protein and mRNA expression. Either SM or PNA treatment is able to reduce β‐catenin activity at 24–72 hours as shown by decrease in β‐catenin‐TCF luciferase reporter in multiple HCC cell lines. Concomitantly, decreased β‐catenin activity led to a reduction in cell viability (MTT) and proliferation (Thymidine Incorporation), while increasing the number of apoptotic cells (TUNEL). Following treatment of either SM or PNA also results in decreases in β‐catenin driven pro‐survival, proliferation, and pro‐angiogenesis genes such as Cyclin D1, GS, and VEGF‐A. Thus we report two independent strategies, one reducing β‐catenin overactivity in HCC by targeting β‐catenin‐β interactions in nuclei, and second decreasing β‐catenin gene expression. Both strategies lead to down regulation of β‐catenin target genes in HCC cells, thus impacting tumor biology and hence have significant therapeutic implications.