Cloning, expression of the truncation of recombinant peroxidase derived from millet bran and its reversal effects on 5-Fu resistance in colorectal cancer.

A novel peroxidase (FMBP) was extracted and purified from foxtail millet bran in our previous study and it possessed excellent anti-colon cancer activity both in vitro and in vivo. However, the active fragment of FMBP responsible for the anti-colon cancer effects remains unclear. In present, three different truncated sequences of FMBP were designed and cloned into a plasmid vector (pMal-s). Three recombinant segments were successfully expressed in host strain Escherichia coli DH5α induced by IPTG (0.3 mM) at 37 °C for 4 h, respectively named MBP-FMBP-1, MBP-FMBP-2 and MBP-FMBP-3. MTT assay showed that only MBP-FMBP-2 possessed significant anti-colon cancer activity, and its anti-colon cancer activity was equivalent to FMBP. Further, the results showed that MBP-FMBP-2 significantly reversed the 5-Fu resistance in human colorectal cancer HCT-8/Fu cell through inhibiting cell proliferation, promoting cell apoptosis and increasing the intracellular accumulation of 5-Fu. RT-PCR and western blot assays showed that MBP-FMBP-2 also decreased the expression levels of multi-drug resistance protein 1 (MRP1), P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP). These results indicate that MBP-FMBP-2 is the effective segment of FMBP which exhibits anti-colon cancer activity and has potential as an outstanding chemotherapeutic agent against colon cancer.