Apigenin as an effective anticancer natural product: Spotlight on TRAIL, WNT/β-catenin, JAK-STAT pathways, and microRNAs

Wealth of information gleaned from decades of high-impact research work; scientists have disentangled the complicated web of versatile regulators that underlie cancer development and progression. Use of structural biology approaches and functional genomics have helped us to gain new insights into complex nature of cancer, and it is now clear that genetic/epigenetic mutations, overexpression of oncogenes, inactivation of tumor suppressors, loss of apoptosis, and versatility of protein binding partners have contributory roles in carcinogenesis and metastatic spread. It is becoming progressively more understandable that reprogramming of gene expression during and nontranscriptional changes during cancer development and progression are initiated and controlled by deregulated signal transduction cascades, all of which collectively create an incalculable complexity. Data obtained through preclinical and clinical trials revealed that alterations in the targeted oncogenes and other downstream, and parallel pathways played a central role in the development of resistance against different therapeutics. Phytochemicals have regained limelight, and different natural products are currently being tested for efficacy in preclinical studies. Apigenin, a plant-derived flavonoid has considerable pharmacological value and is reportedly involved in the regulation of different signaling cascades. In this review, we have attempted to summarize rapidly evolving understanding of molecular biologists and pharmacologists about the potential of apigenin in the regulation of deregulated signaling pathways in different cancers. We have emphasized on the regulation of WNT/β-catenin and janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways. We also comprehensively discuss how apigenin restored apoptosis in tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-resistant cancers. The review also gives a snapshot of microRNAs (miRNAs) that regulate wide-ranging biological processes, and it is now clear that each miRNA can control hundreds of gene targets. Apigenin was noted to upregulate miR-520b and miR-101 in different cancers to inhibit tumor growth. Moreover, apigenin-induced apoptotic rate was significantly higher when used in combination with miR-423-5p inhibitors or miR-138 mimics. Better comprehension of linear and integrated signaling pathways will be helpful in effective therapeutic targeting of deregulated signaling pathways to inhibit/prevent cancer.