Unraveling Key Signaling Pathways Altered in Hepatocellular Carcinoma

Abstract

Hepatocellular carcinoma (HCC) is becoming one of the major health problems, and the leading cause of cancer-related mortality globally. Its multifactorial risk factors remain as paramount challenges to the treatment of this deadly disease. The conventionally known risk factors that trigger HCC include hepatitis C virus (HCV), hepatitis B virus (HBV), excess alcohol consumption, and environmental toxins, such as aflatoxin, aristolochic acid, etc. All these risk factors activate the oncogenic signaling in the liver, and transform the normal liver into an HCC liver. Recently, globalization and the Western sedentary lifestyle have newly emerged as risk factors for HCC, which include obesity, metabolic syndrome, and associated clinical and pathological modalities. In addition, a number of cellular signaling pathways are derailed in HCC, and these pathways, which are altered in HCC, are known to be directly controlled by oncogenes, such as KRAS, BRAF, c-MYC, astrocyte elevated gene-1 (AEG-1), staphylococcal nuclease domain containing 1 (SND1), late SV40 factor (LSF), apoptosis-antagonizing transcription factor (AATF), WNT/β-catenin, TGF-β, etc. All these oncogenes activate the oncogenic signaling in HCC, and suppress the important cellular tumor suppressor protein activity, playing a prominent role in hepatocarcinogenesis, and its development and progression. The present review established a novel interconnected network between all these oncogene-associated proteins, in order to determine its role in deregulating normal cellular signaling pathways, and transforming these into oncogenic signaling. A number of these oncogenes regulate the miRNA-RISC-associated oncogenic signaling, and trigger oncogenic miRNA singling by downregulating various tumor suppressor genes. Therefore, therapeutically targeting these oncogenes and associated proteins would aid in the development of new drugs to treat HCC.