Reversion Impact of Peptide Extract from Scorpion Venom on Multidrug-resistance of Leukemia Stem Cell Line K562/A02 in vivo

Objective To investigate the molecular mechanism of the reversion impact of peptide extract from scorpion venom(PESV) on multidrug resistance(MDR) of leukemia stem cells(LSC) in vivo. Methods Took leukemia BALB/c nude mice modeled by K562/A02 cell line for example, they were randomly divided into six groups: Model control group, ADM group, PESV group, ADM+PESV high-dose(H) group, ADM+PESV middle-dose(M) group, and ADM+PESV low-dose(L) group. Model control group received an equal volume of 0.9% sodium chloride solution by means of intraperitoneal injection, and other groups received the corresponding dose of ADM and (or) PESV in the same way, and all groups were continuously medicated for 14d. On d21, the transplanted tumor growth were observed in nude mice of each group, and we respectively detected the LSC in the tumor block: the expression levels of P-gp on the membrane, the content of ALDH and PI3-K in the cytoplasm, and the activities of MDR1 and NF-κB in the nucleus. Results Before and after K562/A02 cells were selected with immunomagnetic beads, CD34+CD38- cells ratio and IC50 were 31.5% and (60.33±10.68) μg/ml, 92.8% and (58.33±9.72) μg/ml, respectively. After the selection, the stemness of the cells was significantly improved, while no difference of drug-resistance was showed. Tumor formation rate of modeled mice in each group was 100%. The testing results of LSC in the tumor block were as follows: the expression of P-gp on the membrane tested by flow cytometry were 89.8% in model control group, 91.9% in ADM group, 88.4% in PESV group, 53.9% in ADM+PESV(H) group, 78.0% in ADM+PESV(M) group, and 78.7% in ADM+PESV(L) group; the expression levels of MDR1 mRNA detected by semiquantitative RT-PCR were PESV group>ADM+PESV(L) group> ADM+PESV(M) group> ADM+PESV(H) group>ADM group; the gray values of ALDH tested by immunohistochemistry were ADM group>PESV group> ADM+PESV(H) group>ADM+PESV(M) group> ADM+PESV(L) group; PI3-K protein and NF-κB factor were respectively detected by Western blot and Elisa, and both expression levels were up-regulated in ADM group and PESV group, down-regulated in ADM+PESV groups, moreover, the down-regulated levels showed a positive correlation with the dose of PESV. Conclusion PESV could reduce the expression levels of P-gp on the membrane, ALDH and PI3-K expression in the cytoplasm, and MDR1 and NF-κB expression in the nucleus, which result in enhancing the sensitivity of LSC K562/A02 to ADM and eventually reversing its multidrug resistance.