The fundamental units that make up the human body are cells. Cells usually die when they get too old or damaged; new cells replace the old ones. Suppose the cells are not performing the proper function and are characterized by abnormal cell development with the ability to infiltrate and spread to other sections of the body- termed cancer. Changes in the genes that govern normal bodily processes are one of the components implicated in cancer beginning.
Phytochemicals are plant-produced chemical substances that aid in fungus, bacteria, and plant virus resistance. When people consume plants (herbs, fruits, and vegetables), phytochemicals are absorbed and transported into the body’s cells, where they help restore the cells’ compromised functions, such as activating the immune system, suppressing cancer cell proliferation, and preventing DNA damage, all of which can lead to cancer and other diseases.
Dietary phytochemicals (terpenoids, carotenoids, phenolic substances such as flavonoids, isoflavonoids, aurones, chalconoids, flavonolignans, lignans, stilbenoids, curcuminoids, tannins, aromatic acids, phenylethanoids, glucosinolates, betalains, naringenin, resveratrol, EGCG, genistein, curcumin, quercetin, and camptothecin) have been shown to slow cancer development and act as anti-metastatic and apoptotic agents.
Phytochemicals are interfering with a critical cancer regulator.
MicroRNAs (produced by the cellular machinery) – are essential for fine-tuning gene expression in both standard and diseased cells – via the expression of proteins (Proteins are involved in completing the cell’s regulatory functions (growth, survival, and death)); when genetic changes disrupt this standard system – dysfunction (up or downregulation) of microRNA, aids cancer cell growth. Due to their oncogenic or tumor suppressor properties, miRNAs are being explored as exciting cancer prevention and treatment targets.
Several preclinical animal models and human epidemiological studies, including dietary phytochemicals, have been related to a lower incidence of metastatic cancer. Dietary phytochemicals modulate various biological events, including epigenetic events such as non-coding microRNAs, histone modification, DNA methylation, and multiple signaling transduction pathways. Several studies have found that one of the critical mechanisms in the anticancer activities of various phytochemicals appears to be miRNA alteration.
When phytochemicals enter a dysfunctional cell, they regulate microRNA production, either boosting the synthesis of promising miRNAs (which helps to limit cancer cell development) or lowering the influence of non-beneficial miRNAs, which suppresses cancer cell proliferation.
Reported Efficacy of Phytochemicals on miRNA
Curcumin has been associated with a 2.5-fold rise in miR-186, responsible for causing apoptosis in A549/DDP multidrug-resistant human lung adenocarcinoma cells. Curcumin decreased the expression of miR-196 (an oncogenic miR) in stomach tumors while boosting the expression of miR-22 (a tumor suppressor miR).
Resveratrol inhibited AP-1 expression in monocytic cells by upregulating miR-663 and simultaneously reducing the expression of oncogenic miR-1551. In HepG2 cells, the ellagitannin 3-di-O-galloyl-4,6-(s)-HHDP-b-D-glucopyranose was reported to regulate the expression of let-7 family members miR-370, miR-373, and miR-526b, inhibiting metastatic processes including proliferation and differentiation.
I3C (indole-3-carbinol) restores miRNAs that inhibit tumour cell proliferation, such as miR-146 (NF-B activation); miR-192 (Ras activation); let-7a, let-7c (cell proliferation, angiogenesis, Ras activation); and miR-123, miR-99b (angiogenesis, cell proliferation, apoptosis), and miR-222 (angiogenesis, cell proliferation).
Phytochemicals vs. Chemo-prevention
The phytochemicals assist in breaking the resistance of cancer cells to pharmaceuticals; can be used to develop therapeutic techniques that work in tandem with traditional treatments to enhance cancer therapy and prevention. They are also chemopreventive as Dietary polyphenols have the potential to improve chemotherapy and radiation efficacy by modulating numerous miRNA and hence their target genes.
Chemoprevention of cancer is a relatively new advanced field that offers a practical way to identify possible helpful inhibitors of cancer growth and the research tumor formation. Due to their remarkable evidence of inhibiting the process of cancer formation, dietary polyphenols from vegetables, fruits, medicinal herbs, and spices have piqued the interest of many researchers and the general public.
Prevailing Loopholes
Despite phytochemicals’ powerful anticancer capabilities, concerns have been raised about precise targeting and bioavailability. To address these obstacles in the phytochemical application, several ways are being investigated, such as chemical modification, synthetic formulation, nanoparticle delivery, etc.