?-Catenin knockdown in liver tumor cells by a cell permeable gamma guanidine-based peptide nucleic acid.

ABSTRACT: Hepatocellular cancer (HCC) is the third cause of death by cancer worldwide. In the current study we target ?- catenin, an oncogene mutated and constitutively active in 20-30% of HCCs, via a novel, cell permeable gamma guanidine-based peptide nucleic acid (?GPNA) antisense oligonucleotide designed against either the transcription or the translation start site of the human ?-catenin gene. Using TOPflash, a luciferase reporter assay, we show that ?GPNA targeting the transcription start site showed more robust activity against ?-catenin activity in liver tumor cells that harbor ?-catenin gene mutations (HepG2 & Snu-449). We identified concomitant suppression of ?-catenin expression and of various Wnt targets including glutamine synthetase (GS) and cyclin-D1. Concurrently, ?GPNA treatment reduced proliferation, survival and viability of HCC cells. Intriguingly, an angiogenesis quantitative Real-Time-PCR array identified decreased expression of several pro-angiogenic secreted factors such as EphrinA1, FGF-2, and VEGF-A upon ?-catenin inhibition in liver tumor cells. Conversely, transfection of stabilized-?-catenin mutants enhanced the expression of angiogenic factors like VEGF-A. Conditioned media from HepG2 cells treated with ?-catenin but not the mismatch ?GPNA significantly diminished spheroid and tubule formation by SK-Hep1 cells, an HCC-associated endothelial cell line. Thus, we report a novel class of cell permeable and efficacious ?GPNAs that effectively targets ?-catenin, a known oncogene in the liver. Our study also identifies a novel role of ?-catenin in liver tumor angiogenesis through paracrine mechanisms in addition to its roles in proliferation, survival, metabolism and cancer stem cell biology, thus further strengthening its effectiveness as a therapeutic target in HCC.

SUBMITTER: Delgado E 

PROVIDER: S-EPMC4098753 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature