Modulating Pluripotency Network Genes with Omega-3 DHA is followed by Caspase- 3 Activation and Apoptosis in DNA Mismatch Repair-Deficient/KRAS-Mutant Colorectal Cancer Stem-Like Cells.

BACKGROUND: Targeting DNA mismatch repair-deficient/KRAS-mutant Colorectal Cancer Stem Cells (CRCSCs) with chemical compounds remains challenging. Modulating stemness factors Bmi-1, Sox-2, Oct-4 and Nanog in CRCSCs which are direct downstream targets of carcinogenesis pathways may lead to the reactivation of caspase-3 and apoptosis in these cells. Omega-3 DHA modulates different signaling pathways involved in carcinogenesis. However, little is known, whether in vitro concentrations of DHA equal to human plasma levels are able to modulate pluripotency genes expression, caspase-3 reactivation and apoptosis in DNA mismatch repair-deficient/KRAS-mutant CRC stem-like cells. METHODS: DNA mismatch repair-deficient/KRAS-mutant CRC stem-like cells (LS174T cells) were treated with DHA, after which, cell number and proliferation-rate, Bmi-1, Sox-2, Nanog and Oct-4 expression, caspase-3 activation and apoptosis were evaluated with different cellular and molecular techniques. RESULTS: DHA changed the morphology of cells to apoptotic forms and disrupted cell connections. After 48h treatment with 50- to 200µM DHA, cell numbers and proliferation-rates were measured to be 86%-35% and 93.6%-45.7% respectively. Treatment with 200 µM DHA dramatically decreased the expression of Bmi-1, Sox- 2, Oct-4 and Nanog by 69%, 70%, 97.5% and 53% respectively. Concurrently, DHA induced caspase-3 activation by 1.8-4.7-fold increases compared to untreated cells. An increase in the number of apoptotic cells ranging from 9.3%-38.4% was also observed with increasing DHA concentrations. CONCLUSIONS: DHA decreases the high expression level of pluripotency network genes suggesting Bmi-1, Sox-2, Oct-4 and Nanog as promising molecular targets of DHA. DHA reactivates caspase-3 and apoptosis in DNA mismatch repair-deficient/KRAS-mutant CRC stem-like cells, representing the high potential of this safe compound for therapeutic application in CRC.

Carboxyamidotriazole Synergizes with Sorafenib to Combat Non-Small Cell Lung Cancer through Inhibition of NANOG and Aggravation of Apoptosis.

Lung cancer is currently the leading cause of cancer-related deaths worldwide. In this study, we investigated the combination of carboxyamidotriazole (CAI) and sorafenib in non-small cell lung cancer (NSCLC) in vitro and in vivo to test whether CAI enhances the antitumor effects of sorafenib and reduces its side effects. The combination index (CI) showed that coadministration of CAI and sorafenib synergistically inhibited the proliferation of NSCLC cells (Lewis lung carcinoma, A549, and NCI-H1975 cells). Cell death as a result of the combination treatment was attributed to apoptosis, which was accompanied by activation of caspase-3 and poly(ADP-ribose) polymerase. In addition, combination therapy induced the accumulation of mitochondrial-associated reactive oxygen species, as well as depolarization of mitochondrial and reduced NANOG (homeobox protein NANOG) mRNA and protein expression. Basic fibroblast growth factor, a stimulator of NANOG, was applied to identify the possible mechanism. The addition of basic fibroblast growth factor followed by combined treatment may stimulate NANOG expression and synchronously rescue the accumulation of reactive oxygen species. C57BL/6J mice bearing Lewis lung carcinoma were randomized to receive vehicle (polyethylene glycol 400), CAI (30 mg/kg), low-dose sorafenib (SFB-L; 10 mg/kg), high-dose sorafenib (SFB-H; 30 mg/kg), or a CAI and SFB-L combination. Tumor growth was significantly suppressed in the combination group, and the efficacy of combination treatment was equivalent to that of the SFB-H monotherapy group. Furthermore, the combination group had reduced side effects compared with the SFB-H group, as indicated by weight preservation in mice. Our study illustrates that CAI enhances the antitumor activity of sorafenib in NSCLC and provides a novel strategy for NSCLC treatment.