No abstract

Direct ER treatment may prove to be an attractive alternative therapy in the treatment of human colorectal tumors in the future.

EGFR-inhibitor (Cetuximab) is one of the main targeted drugs used for metastatic colorectal carcinoma (CRC). The benefit from Cetuximab appears to be limited to a subtype of patients, not for the patients with tumors harboring mutated BRAF or KRAS genes; unfortunately, it accounts for ~40-50% of CRC cases. Previous studies have connected higher expression levels of miR-378 to be commonly presented in patients without BRAF or KRAS mutants than in mutated CRCs. The microRNA-378 (miR-378) is coexpressed with PGC-1β and can be easily induced by fatty acid, for example lauric acid. Therefore, we hypothesized that elevation of miR-378 expression in mutated CRCs may stimulate the cell response to Cetuximab. Herein, seven CRC cell lines with confirmed mutation status were involved in two parallel experiments; directly in vitro transfected miR-378 mimics, and using lauric acid to indirectly induce the level of miR-378 in cells. After the increase of miR-378 in cells by either direct or indirect approaches, sensitivity to Cetuximab was restored in all BRAF mutants (p-value <0.0001-0.0003), and half of KRAS mutants CRC (p-value 0.039-0.007). Further evidence was gained by decreasing expression of MEK and ERK2 proteins after transfection with miR-378; it was similar to the indirect induction by lauric acid approach. In conclusion, the present study demonstrated that lauric acid may efficiently induce miR-378 expression in CRC mutants, and both BRAF and a subtype of KRAS mutants presented significantly improved sensitivity to Cetuximab. Notably, BRAF mutants could even be inhibited in cell proliferation after elevated concentration of miR-378 in cells without combining with targeted therapy. This new approach may shed new light on BRAF or KRAS mutation in CRC patients for clinical trial, since lauric acid may easily be obtain from natural food, and it is supposed to be harmless to the cardiovascular system.

Effects of puerarin, an active principle contained in the roots of Pueraria lobata (Leguminosae), on the regulation of glucose metabolism in an insulin deficient state were investigated in cultured myoblast C 2 C 12 cells using glucose uptake as indicator. Puerarin enhanced the uptake of radioactive glucose into C 2 C 12 cells in a concentration-dependent manner, which was abolished by prazosin pretreatment. Activation of alpha 1 -adrenoceptors by puerarin was further indicated by the displacement of [ 3H]prazosin binding in C 2 C 12 cells. The stimulatory action of puerarin on glucose uptake was also reduced in C 2 C 12 cells pre-incubated with the antagonists, both WB 4101 and RS 17 056, at concentrations sufficient to block alpha 1A -adrenoceptor (alpha 1A -AR). An activation of alpha 1A -AR seems responsible for the action of puerarin in C 2 C 12 cells. Pharmacological inhibition of phospholipase C (PLC) by U73312 resulted a concentration-dependent decrease of puerarin-stimulated glucose uptake in C 2 C 12 cells. This inhibition of glucose uptake by U73122 was specific because the inactive congener, U73343, failed to block puerarin-stimulated glucose uptake. Moreover, both chelerythrine and GF 109203X diminished the action of puerarin at concentration sufficient to inhibit protein kinase C (PKC). The obtained data suggest that an activation of alpha 1A -AR by puerarin in C 2 C 12 cells may increase the glucose uptake via the PLC-PKC pathway.