Morin supplementation modulates PERK branch of UPR and mitigates 1,2-dimethylhydrazine-induced angiogenesis and oxidative stress in the colon of experimental rats.

Angiogenesis, disturbance in redox homeostasis, and deregulated redox signaling are considered as common hallmarks of cancer progression and chemo resistance. In this context, PERK (protein kinase PKR-like ER kinase) branch of the unfolded protein response (UPR), an adaptive mechanism triggered by endoplasmic reticulum (ER) stress to cope with protein misfolding and perturbed proteostasis, has shown to regulate angiogenesis and oxidative stress. This study aimed to investigate the impact of morin, a poly phenolic compound from the family of Moraceae on PERK-Nrf2-VEGF axis in experimental rats challenged with the colon specific procarcinogen 1,2-dimethylhydrazine (DMH). Male albino Wistar rats were randomized into four groups (n = 6) viz., control, morin control, DMH control, and DMH administered rats treated with morin. Immunohistochemical analysis of colonic cross-section revealed that DMH alone administered rats showed significantly increased expression of Nrf2 predominantly in the cytoplasm. Angiogenic growth factors viz., VEGF, PDGF, and bFGF are also shown to be increased in the DMH alone administered tumor bearing rats as compared to control. Significant downregulation was also observed in the downstream targets of Nrf2 such as hemeoxygenase 1 (HO1), glutathione peroxidase 2 (GPX2), thioredoxin (TRXN), glutathione S transferase (GST), and uridine glucuronyl transferase (UGT) as evidenced by the qPCR analysis. Immunoblot analysis revealed that onset of oxidative stress and angiogenesis in the colon of DMH alone administered rats were due to downregulation of pPERK along with its downstream targets such as peIF2α and CHOP. Supplementation of morin reversed the DMH-induced alterations and suppresses oxidative stress and angiogenesis via PERK phosphorylation.

Supplementation of p-coumaric acid exhibits chemopreventive effect via induction of Nrf2 in a short-term preclinical model of colon cancer.

Suppression of colorectal cancer by means of chemoprevention is gaining great attention owing to promising outcomes with less adverse effects in preclinical and clinical trials. The present study aims to explore the mechanism of chemoprevention by p-coumaric acid (p-CA) in a short-term preclinical model of colon cancer. 1,2-dimethylhydrazine-administered rats supplemented with p-CA showed downregulation of the expression of colonic proteins, namely, cyclin B1, cdc2 and mdm2, which regulate cell cycle, and immediate early response genes, namely, c-fos, c-jun and c-myc, which regulate cell proliferation. Apoptosis induction was also observed in the colon of p-CA-supplemented rats as assessed by the Bax/Bcl-2 ratio. Immunohistochemistry, immunoblotting and real-time polymerase chain reaction analysis revealed that supplementation of p-CA improved the in-vivo detoxification potential by modulating the cytoplasmic-to-nuclear ratio of nuclear factor erythroid 2-related factor 2, favouring the induction of genes responsible for cytoprotection and detoxification. The outcome of these findings suggests that p-CA inhibited polyp formation by improving the process of detoxification and apoptosis in the colon of 1,2-dimethylhydrazine-administered rats.

Antiproliferative effect of p-Coumaric acid targets UPR activation by downregulating Grp78 in colon cancer.

p-CA is a naturally occurring phenolic acid present in most plants and in all commonly consumed vegetables and fruits. Here we demonstrated the anti-cancer effect of the food borne phytochemical p-CA both in vitro and in vivo models of colon cancer using growth rate and tumor incidence as endpoints. Glucose regulated protein (GRP78) induction and UPR activation plays a key role in oncogenic progression, therefore increased dependence of cancer cells on these UPR signaling pathways for survival can be exploited for anti-cancer research. Hence we investigated the effect of p-CA on Grp78 a molecular chaperone often upregulated in colon cancer and its impact on unfolded protein response (UPR). Administration of the procarcinogen 1,2- dimethylhydrazine (DMH) causes Grp78 upregulation and tumor adaptation via UPR activation. The adaptive activity of UPR activates antiapoptotic NF-κB that results in upregulation of the markers of inflammation and angiogenesis. Supplementation of p-CA downregulated Grp78 and activated UPR mediated apoptosis both in in vitro and in vivo models of colon cancer. Further we observed that p-CA significantly reduced inflammation by decreasing the expression of cytokines COX-2, IL-6, TNF-α and PGE2 as analyzed by q-PCR and also reduced the expression of p-p65 and p-IκBα as analyzed by western blot. Further mechanistic insights revealed that p-CA inhibits Grp78 upregulation in cancer cells through activation of PERK-eIF2α-ATF-4-CHOP pathway that culminates in apoptosis inducing effect of p-CA.

Molecular chemoprevention by morin - A plant flavonoid that targets nuclear factor kappa B in experimental colon cancer.

Colorectal cancer is the third most common cancer worldwide. The development of effective, inexpensive and safe chemopreventive agents would be of great benefit as it involves use of natural products to prevent or suppress the progression of precursor lesions. Morin a flavonoid found in figs (Ficus carica) and other plants is shown to inhibit 1,2-dimethylhydrazine (DMH) induced colon cancer progression in a short term and long term model of colon cancer rats; however, the molecular target for the colon cancer chemoprotective efficacy of morin is yet to be discovered. The present study aims to explore the molecular basis of how morin contributes to the chemoprevention with a focus on NF-κB signaling pathway. The effect of morin on NF-κB signaling in DMH-induced carcinogenic events such as inflammation and apoptosis were analyzed by studying the histopathological analysis using Hematoxylin and Eosin staining (H &E), mRNA expression using q-PCR, protein expression using Immunohistochemistry (IHC) and western blot. Morin supplementation to DMH administered rats down regulated NF-κB pathway and its downstream inflammatory mediators like tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), cyclooxygenase 2 (COX-2) and prostaglandin (PGE-2). Morin supplementation to DMH administered rats alters BAX/BCL2 ratio favoring apoptosis in carcinogen treated rats. Our findings explored that molecular chemoprevention of morin targets NF-κB and acts as a potent anti-inflammatory and pro-apoptotic agent for colon cancer prevention.

Protective effect of p-coumaric acid against 1,2 dimethylhydrazine induced colonic preneoplastic lesions in experimental rats.

Oxidative stress and gut microbial enzymes are intricately linked to the onset of colon carcinogenesis. Phytochemicals that modulate these two factors hold promise for the development of such agents as anticancer drugs. The present study evaluates the chemopreventive potential of p-coumaric acid (p-CA) - a phenolic acid in rats challenged with the colon specific procarcinogen DMH (1,2 di-methyl hydrazine). Rats were randomized into six groups (n=7/group). Group 1 (control); Group 2 (p-CA 200mg/kg b.w.); Group 3 (DMH 40mg/kg b.w.); Groups 4 (DMH+p-CA 50mg/kg b.w.) and Group 5 (DMH+p-CA 100mg/kg b.w.) and Group 6 (DMH+p-CA 200mg/kg b.w.). After the experimental duration of 15 weeks' rats were subjected to necropsy and tissues were collected for the histological and biochemical investigations. DMH induced colonic preneoplastic lesions viz., aberrant crypt foci (ACF), dysplastic ACF (DACF), mucin depleted foci (MDF) and beta catenin accumulated crypts (BCAC) were significantly suppressed by p-CA supplementation. Glucuronide conjugation of DMH in liver and its subsequent deconjugation mediated by microbes in the colon induced the formation of colonic preneoplastic lesions. p-CA inhibited these lesions and protected the rat colon against genotoxic insult by scavenging the free radicals via its strong antioxidant response and detoxification mechanism as measured by TBARS and enzymic antioxidants in control and experimental rats. Of the three tested doses, p-CA at a dose of 100mg/kg body weight is found to exhibit a significant optimum effect compared to the other two doses 50mg/kg body weight and 200mg/kg body weight.

Morin and Esculetin supplementation modulates c-myc induced energy metabolism and attenuates neoplastic changes in rats challenged with the procarcinogen 1,2 - dimethylhydrazine.

Targeting tumor metabolism by natural products is a novel approach and provides rationale for anti-cancer drug discovery. The present study aims to explore the impact of morin and/or esculetin on c-myc induced energy metabolism in 1,2-dimethylhydrazine (DMH) induced colon cancer in rats. In order to achieve this aim we analyzed the expression of glucose and glutamine transporters and the key enzymes of glycolytic pathway besides the markers of neoplastic changes viz., mucin depleted foci (MDF), beta catenin accumulated crypts (BCAC), and markers of cell proliferation viz., proliferating cell nuclear antigen (PCNA), argyrophilic nucleolar antigen (AgNOR), c-myc, c-jun and c-fos. All the parameters tested in the present study are highly influenced by the phytochemicals morin and/or esculetin in a way to prevent colon carcinogenesis. Morin and/or esculetin supplementation effectively targets tumor metabolism via ß-cateinin/c-myc signaling and affects glycolysis and glutaminolysis to abrogate colon cancer in rats. The anti-cancer effect of morin is more pronounced than esculetin. The effect obtained through the combined treatment of morin and esculetin is comparable to that of individual supplementation of morin and there is no synergistic effect. Overall individual supplementation of morin scores well as a potential anticancer agent targeting glycolysis and glutaminolysis in colon cancer.

Terpenoids as anti-colon cancer agents - A comprehensive review on its mechanistic perspectives.

Multistep model of colon carcinogenesis has provided the framework to advance our understanding of the molecular basis of colon cancer. This multistage process of carcinogenesis takes a long period to transform from a normal epithelial cell to invasive carcinoma. Thus, it provides enough time to intervene the process of carcinogenesis especially through dietary modification. In spite of the in-depth understanding of the colon cancer etiology and pathophysiology and its association with diet, colon cancer remains a major cause of cancer mortality worldwide. Phytochemicals and their derivatives are gaining attention in cancer prevention and treatment strategies because of cancer chemotherapy associated adverse effects. Being the largest group of phytochemicals traditionally used for medicinal purpose in India and China, terpenoids are recently being explored as anticancer agents. Anticancer properties of terpenoids are associated with various mechanisms like counteraction of oxidative stress, potentiating endogenous antioxidants, improving detoxification potential, disrupting cell survival pathways and inducing apoptosis. This review gives a comprehensive idea of naturally occurring terpenoids as useful agents for the prevention of colon cancer with reference to their classes, sources and molecular targets. Based on the explored molecular targets further research in colon cancer chemoprevention is warranted.

Chemopreventive agents targeting tumor microenvironment.

Recent studies have shown that tumor development and progression depend not only on the perturbed genes that govern cell proliferation, but is also highly determined by the non-tumor cells of the stromal compartment surrounding the tumor called tumor microenvironment (TME). These findings highlight the importance of targeting the microenvironment in combination with therapies aimed at tumor cells as a valuable approach. The innate and adaptive immune cells in the TME interact among themselves and also with the endothelial cells, pericytes and mast cells of the stromal compartment through various autocrine and paracrine manner to regulate abnormal cell proliferation. Direct cytotoxic killing of cancer cells and/or reversion of the immunosuppressive TME are to be considered as better strategies for chemoprevention and chemotherapy. With a growing emphasis on a "hallmark targeting" strategy for cancer therapy, the TME now appears as a promising target for cancer prevention using natural products. Clarification on the nontumor stromal cells, the mediators involved, interactions with immune response cells, and immune-evasive mechanisms are needed in order to manipulate the characteristics of the TME by natural pharmacological agents to design effective therapies. This review will provide a glimpse on the roles played by various non-tumor cells in tumor progression and their intervention by pharmacological agents.