Anti-Inflammatory Plant Natural Products for Cancer Therapy

Much of the current research in cancer therapeutics is aimed at developing drugs or vaccines to target key molecules for combating tumor cell growth, metastasis, proliferation, or changes in the associated stromal microenvironment. Studies on a wide spectrum of plant secondary metabolites extractable as natural products from fruits, vegetables, teas, spices, and traditional medicinal herbs show that these plant natural products can act as potent anti-inflammatory, antioxidant or anticancer agents. The recent advances in genomics and metabolomics have enabled biologists to better investigate the potential use of immunomodulatory natural products for treatment or control of various cancerous diseases. The cancer preventive or protective activities of the various immunomodulatory natural products lie in their effects on cellular defenses including detoxifying and antioxidant enzyme systems, and the induction of anti-inflammatory and antitumor or antimetastasis responses, often by targeting specific key transcription factors like nuclear factor kappa B (NF-kappa B), activator protein (AP-1), signal transducers and activators of transcription ( STAT) and others. This review presents recent findings and hypotheses on the molecular mechanisms through which various inflammatory activities are linked to tumorigenic processes and the specific immunomodulatory natural products that may suppress inflammation and the associated tumor progression and metastasis both in vitro and in vivo. In addition to tumor cells per se, the various associated roles of myeloid-derived suppressor cells, stromal fibroblasts, myofibroblasts, and inflammatory immune cells, and the possible effects of phytomedicines on these cells in the tumor microenvironment will be discussed.