Enhancement of the Antitumor Effect of Methotrexate on Colorectal Cancer Cells via Lactate Calcium Salt Targeting Methionine Metabolism

The potential therapeutic effect of melatonin in oxaliplatin combination therapy against chemoresistant colorectal cancer cells

BACKGROUND

Oxaliplatin is one of the main therapeutics in colorectal cancer (CRC) chemotherapy. However, in light of multidrug resistance (MDR) phenotype development, the efficacy of oxaliplatin has decreased. This study aimed to assess the potential therapeutic effect of melatonin in oxaliplatin combination therapy for drug-resistant colorectal cancer cells.

METHODS AND RESULTS

Initially, the oxaliplatin-resistant cell line was created of LS174T (LS174T/DR) by using the oxaliplatin IC50 concentration and resting cycles. MTT assays and flow cytometry were applied for assessing cell viability and apoptotic cells. The mRNA expression level of Bax, Bcl2, MT1, MT2, and ABCB1 as well as protein levels of ABCB1, Bcl2, BAX were measured by the qRT-PCR and western blot techniques respectively. P-gp activity was assessed by Rho123 staining. The IC50 concentration of oxaliplatin in resistant cells was increased from 500.7 ± 0.2 nM to 7119 ± 0.1 nM. Bcl2, MT1, MT2, and ABCB1 mRNA plus protein expression levels of Bcl2 and ABCB1 were significantly reduced in resistant cells, along with a marked increase in Bax mRNA and protein levels compared to parental cells. Rho 123 staining revealed a marked reduction in P-gp activities in the combination-treated group compared to the oxaliplatin-treated group.

CONCLUSIONS

The results of cytotoxicity assays, MTT, and flow cytometry revealed that the combination of melatonin and oxaliplatin exerts synergistic effects on induction of oxaliplatin's cytotoxicity in CRC. Our research suggests that combining the treatments of melatonin and oxaliplatin may be considered as a new approach to overcoming oxaliplatin resistance in CRC patients.

A combined treatment with melatonin and andrographis promotes autophagy and anticancer activity in colorectal cancer

Colorectal cancer (CRC) is one of the most frequent malignancies worldwide and remains one of the leading causes of cancer-related deaths in the USA. The high degree of morbidity and mortality associated with this disease is largely due to the inadequate efficacy of current treatments as well the development of chemoresistance. In recent years, several pharmaceutical agents screened from natural products have shown the promise to offer a safe, inexpensive and synergistically multi-targeted treatment option in various cancers. Given the growing evidence of anti-carcinogenic properties of two natural compounds, melatonin (MLT) and andrographis (Andro), we aimed to evaluate their synergistic anticancer effects in CRC. We demonstrate that indeed these two compounds possessed a synergistic anticancer effect in terms of their ability to inhibit cell viability, suppression of colony-formation and induction of apoptosis (P < 0.05). In line with our in vitro findings, we were able to validate this combinatorial anticancer activity in xenograft animal models (P < 0.001) as well as tumor-derived 3D organoids (P < 0.01). RNA-sequencing analysis revealed candidate pathways and genes that mediated antitumor efficacy of MLT and Andro in CRC, among which autophagy pathway and related genes, including NR4A1, CTSL and Atg12, were found to be primarily responsible for the increased anticancer effect by the two natural products. In conclusion, our data reveal a potent and synergistic therapeutic effect of MLT and Andro in the treatment of CRC and provides a rationale for suppressing autophagy in cancer cells as a potential therapeutic strategy for CRC.

Anticancer effect of X-Ray triggered methotrexate conjugated albumin coated bismuth sulfide nanoparticles on SW480 colon cancer cell line

The application of nanoparticles (NPs) as radio-sensitizers and carriers has opened up a new horizon to overcome the limitations of chemo and radiotherapy. In this study, bovine serum albumin-coated Bi₂S₃ NPs (Bi₂S₃@BSA NPs) were synthesized and evaluated in terms of their ability to be used as a radio-sensitizer and carrier for methotrexate (MTX). Physicochemical properties of MTX conjugated Bi₂S₃@BSA NPs (Bi₂S₃@BSA-MTX NPs) were characterized by DLS, TEM, FTIR, UV/Vis, and XRD analyses. After the evaluation of cellular uptake and intracellular localization, the cytotoxicity of the combination of Bi₂S₃@BSA-MTX NPs and X-Ray radiation was analyzed against the SW480 cell line. The synthesized NPs exhibited spherical-like shapes and homogenous morphology, possessing a hydrodynamic diameter of 140.2 ± 5.71 nm (mean ± SD) and zeta potential of -25 mV. Also, the release study showed that the release of MTX is faster and higher in the presence of the proteinase K enzyme than the absence of the enzyme. The results of in-vitro chemo-radiation therapy indicated that the viability of treated cells with Bi₂S₃@BSA-MTX NPs is significantly lower than the cells treated with Bi₂S₃@BSA NPs. Furthermore, cells treated with Bi₂S₃@BSA-MTX NPs showed a lower degree of viability when combined with X-Ray radiation in comparison with the absence of irradiation, which confirmed the ability of the Bi₂S₃@BSA-MTX NPs as radio-sensitizer.