Metastasis suppressors: a paradigm shift in cancer biology

Molecular principles underlying aggressive cancers

Aggressive tumors pose ultra-challenges to drug resistance. Anti-cancer treatments are often unsuccessful, and single-cell technologies to rein drug resistance mechanisms are still fruitless. The National Cancer Institute defines aggressive cancers at the tissue level, describing them as those that spread rapidly, despite severe treatment. At the molecular, foundational level, the quantitative biophysics discipline defines aggressive cancers as harboring a large number of (overexpressed, or mutated) crucial signaling proteins in major proliferation pathways populating their active conformations, primed for their signal transduction roles. This comprehensive review explores highly aggressive cancers on the foundational and cell signaling levels, focusing on the differences between highly aggressive cancers and the more treatable ones. It showcases aggressive tumors as harboring massive, cancer-promoting, catalysis-primed oncogenic proteins, especially through certain overexpression scenarios, as predisposed aggressive tumor candidates. Our examples narrate strong activation of ERK1/2, and other oncogenic proteins, through malfunctioning chromatin and crosslinked signaling, and how they activate multiple proliferation pathways. They show the increased cancer heterogeneity, plasticity, and drug resistance. Our review formulates the principles underlying cancer aggressiveness on the molecular level, discusses scenarios, and describes drug regimen (single drugs and drug combinations) for PDAC, NSCLC, CRC, HCC, breast and prostate cancers, glioblastoma, neuroblastoma, and leukemia as examples. All show overexpression scenarios of master transcription factors, transcription factors with gene fusions, copy number alterations, dysregulation of the epigenetic codes and epithelial-to-mesenchymal transitions in aggressive tumors, as well as high mutation loads of vital upstream signaling regulators, such as EGFR, c-MET, and K-Ras, befitting these principles.

An Overview on the Emerging Role of the Plasma Protease Inhibitor Protein ITIH5 as a Metastasis Suppressor

Most cancers are not detected until they have progressed to the point of becoming malignant and life-threatening. Chemotherapy and conventional medicines are often ineffective against cancer. Although we have made significant progress, new conceptual discoveries are still required to investigate new treatments. The role of metastasis suppressor genes as a therapeutic option for limiting tumor progression and metastasis has been on the anvil for some time. In this review, we discuss the role of ITIH5 as a metastasis suppressor gene and catalog its involvement in different cancers. We further shed light on the mode of action of ITIH5 based on the available data. The review will provide a new perspective on ITIH5 as an anti-metastatic protein and hopefully serve as an impetus for future studies towards the application of ITIH5 for clinical intervention in targeting metastatic cancers.