Curcumin Chemoprevention Reduces the Incidence of Braf Mutant Colorectal Cancer in a Preclinical Study

Starch nanoparticles improve curcumin-induced production of anti-inflammatory cytokines in intestinal epithelial cells

Inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, is a long-term condition resulting from self-sustained intestinal inflammation. Curcumin (Cur), a powerful, naturally occurring antioxidant and anti-inflammatory polyphenol, has been investigated as a therapeutic for IBD, but its poor stability and low bioavailability limits its efficacy. We investigated the use of crosslinked starch nanocarrier (NPL) on the intracellular delivery and the anti-inflammatory efficiency of curcumin. Caco-2 epithelial cells were stimulated with TNFα for 24 h and the anti-inflammatory effects of NPL/Cur formulations were evaluated at the early stages of inflammation (4 h) or later, when fully established (24 h). NPL allowed the intracellular delivery of curcumin, which was enhanced in inflammatory cells, due to a modification of the endocytosis pathways. NPL/Cur decreased the secretion of pro-inflammatory cytokines IL-1β, IL-6 and IL-8 while increasing the anti-inflammatory cytokine IL-10. Finally, the inflammation-related opening of the tight junctions better allowed NPL/Cur to cross the epithelium by paracellular transport. This was confirmed by ex vivo analysis where NPL/Cur, administered to colonic explants from chemically-induced acute colitis mouse model, delivered curcumin deeper in the epithelium. To conclude, NPL/Cur formulation emphasizes the anti-inflammatory effects of curcumin and could constitute a therapeutic alternative in the management of IBD.

Curcumin suppresses cell proliferation and triggers apoptosis in vemurafenib-resistant melanoma cells by downregulating the EGFR signaling pathway

Melanoma is a malignant tumor with aggressive behavior. Vemurafenib, a BRAF inhibitor, is clinically used in melanoma, but resistance to melanoma cytotoxic therapies is associated with BRAF mutations. Curcumin can effectively inhibit numerous types of cancers. However, there are no reports regarding the correlation between curcumin and vemurafenib-resistant melanoma cells. In this study, vemurafenib-resistant A375.S2 (A375.S2/VR) cells were established, and the functional mechanism of the epidermal growth factor receptor (EGFR), serine-threonine kinase (AKT), and the extracellular signal-regulated kinase (ERK) signaling induced by curcumin was investigated in A375.S2/VR cells in vitro. Our results indicated that A375.S2/VR cells had a higher IC₅₀ concentration of vemurafenib than the parental A375.S2 cells. Moreover, curcumin reduced the viability and confluence of A375.S2/VR cells. Curcumin triggered apoptosis via reactive oxygen species (ROS) production, disruption of mitochondrial membrane potential (ΔΨm), and intrinsic signaling (caspase-9/-3-dependent) pathways in A375.S2/VR cells. Curcumin-induced apoptosis was also mediated by the EGFR signaling pathway. Combination treatment with curcumin and gefitinib (an EGFR inhibitor) synergistically potentiated the inhibitory effect of cell viability in A375.S2/VR cells. The present study provides new insights into the therapy of vemurafenib-resistant melanoma and suggests that curcumin might be an encouraging therapeutic candidate for its drug-resistant treatment.

Pre-Administration of Berberine Exerts Chemopreventive Effects in AOM/DSS-Induced Colitis-Associated Carcinogenesis Mice via Modulating Inflammation and Intestinal Microbiota

Inflammatory activation and intestinal flora imbalance play an essential role in the development and progression of colorectal cancer (CRC). Berberine (BBR) has attracted great attention in recent years due to its heath-related benefits in inflammatory disorders and tumors, but the intricate mechanisms have not been fully elucidated. In this study, the effects and the mechanism of BBR on colon cancer were investigated in an azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colitis-associated carcinogenesis mice model. Our results showed that pre-administration of BBR showed a decrease in weight loss, disease activity index (DAI) score, and the number of colon tumors in mice, compared with the model group. The evidence from pathological examination indicated that the malignancy of intestinal tumors was ameliorated after pre-administration of BBR. Additionally, pre-administration with BBR suppressed the expression of pro-inflammatory factors (interleukin (IL)-6, IL-1β, cyclooxygenase (COX)-2 and tumor necrosis factor (TNF)-α) and the cell-proliferation marker Ki67, while expression of the tight junction proteins (ZO-1 and occludin) were increased in colon tissue. Moreover, the levels of critical pathway proteins involved in the inflammatory process (p-STAT3 and p-JNK) and cell cycle regulation molecules (β-catenin, c-Myc and CylinD1) exhibited lower expression levels. Besides, 16S rRNA sequence analysis indicated that pre-administration of BBR increased the ratio of Firmicutes/Bacteroidetes (F:M) and the relative abundance of potentially beneficial bacteria, while the abundance of cancer-related bacteria was decreased. Gavage with Lactobacillus rhamnosus can improve the anti-tumor effect of BBR. Overall, pre-administration of BBR exerts preventive effects in colon carcinogenesis, and the mechanisms underlying these effects are correlated with the inhibition of inflammation and tumor proliferation and the maintenance of intestinal homeostasis.

Low curcumin concentration enhances the anticancer effect of 5-fluorouracil against colorectal cancer

BACKGROUND

Colon cancer treatments include surgery, radiotherapy, and chemotherapy. Chemotherapy using 5-fluorouracil (5-FU) has been widely applied to treat colorectal cancer (CRC). However, it is important to explore the use of chemotherapy drugs in combination with other agents to decrease severe adverse effects.

PURPOSE

This study aimed to investigate the effects of curcumin in combination with 5-FU on the proliferation, migration, and apoptosis of CRC SW620 cell line both in vitro and in vivo.

METHODS

Flow cytometry was used to study the effect of curcumin on chemotherapy-induced apoptosis in CRC cells. The mechanism of curcumin's enhanced antitumor effect in vivo was investigated using gene knockdown, TUNEL, western blot, qRT-PCR and immunohistochemistry.

RESULTS

The results showed a synergistic effect of the two compounds on CRC cells. Considerable reduction in the proliferation and migration of SW620 cells was observed in the combination treatment group. Significantly increased apoptosis rate extended the survival of immunodeficient mice in the combination group as compared to that of the 5-FU group (p < 0.05). The results showed that curcumin significantly inhibited pERK signaling and downregulated L1 expression in SW620 cells.

CONCLUSIONS

We conclude that curcumin promotes chemosensitivity of CRC cells to 5-FU by downregulating L1 expression. Our findings provide experimental evidence for the synergism between curcumin and 5-FU, which can be utilized in clinical applications for reducing the toxicity and adverse effects of 5-FU.