Total Saponins of Rubus Parvifolius L. Exhibited Anti-Leukemia Effect in vivo through STAT3 and eIF4E Signaling Pathways.

Abstract

To investigate the anti-leukemia effect of total saponins of Rubus parvifolius L. (TSRP) on K562 cell xenografts in nude mice and the mechanisms of action. The K562 cell xenografts in nude mice were established, and then randomly divided into 5 groups, the control group, the cytosine arabinoside group(Ara-c) and 3 TSRP groups (20, 40 and 100 mg/kg). The tumor volume and mass of each group of nude mice were measured and the anti-tumor rates of TSRP were calculated subsequently. The apoptosis status of tumor cells was detected by hematoxylin-eosin (HE) and terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) staining analysis. Finally, the activities of apoptosis related signaling of signal transducer and activator of transcription 3 (STAT3), eukaryotic initiation factor 4E (eIF4E) and B-cell lymphoma-2 (bcl-2) were determined with immunohistochemistry tests. Subcutaneous injection of K562 cells induced tumor formation in nude mice, and the TSRP treated group showed a signifificant inhibitory effect on tumor formation. The nude mice treated with TSRP showed a signifificant decrease in tumor growth rate and tumor weight in comparison to the control group (all P<0.05). The HE staining and TUNEL assay showed that TSRP induced cell death by apoptosis. The immunohistochemical assay showed down-regulation of the bcl-2 gene in the TSRP treated cells. The phosphorylation levels of eIF4E and STAT3 were decreased obviously after the treatment of TSRP. TSRP had an excellent tumor-suppressing effect on K562 cells in the nude mice xenograft model, suggesting that TSPR can be developed as a promising anti-chronic myeloide leukemia drug.