[Effect of recombinant VEGF-C secreted from eukaryotic cells on proliferation and chemotherapy-induced apoptosis of leukemic cells].

BACKGROUND & OBJECTIVE: Vascular endothelial growth factor-C/vascular endothelial growth factor receptor-2, -3 (VEGF-C/VEGFR-2,3) signaling pathway can induce angiogenesis/lymphangiogenesis, and promote invasion and metastasis of solid tumors. Recent studies showed that VEGF-C and its receptors also expressed on hematological tumor cells, but their effects on leukemic cells are unclear. This study was to explore the effects of recombinant VEGF-C secreted from VEGF-C cDNA-transfected CHO (CHO/VEGF-C) cells on proliferation and chemotherapy-induced apoptosis of leukemic cells.

METHODS: The effect of recombinant VEGF-C (in the supernatants of CHO/VEGF-C cells) on angiogenesis was observed using the chicken chorioallantoic membrane model. The expression of VEGFR-2 and VEGFR-3 on leukemic cell lines TF-1, K562, HEL, NB4, HL-60, MR2, U937,SHI-1, and RPMI8226 was detected by reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry (FCM). The effect of VEGF-C on the proliferation of NB4 and K562 cells was assessed by MTT assay; its effect on the apoptosis of NB4 cells, which were treated with chemotherapeutic agents [etoposide (VP-16), daunorubicin (DNR), or arsenic trioxide (As2O3)], was investigated by FCM with Annexin V/PI double staining. The supernatant of CHO/pcDNA3.1 cells was used as control.

RESULTS: The recombinant VEGF-C induced angiogenesis in the chicken chorioallantoic membrane model. VEGFR-3 was expressed in NB4, HEL, and RPMI8226 cells; VEGFR-2 was expressed in HEL and TF-1 cells. Compared with the controls, the recombinant VEGF-C promoted the proliferation of NB4 cells (VEGFR-3(+)) (P(24h)=0.006, P(48h)=0.018), but had no effect on K562 cells (VEGFR-3(-)); it inhibited the chemotherapy-induced apoptosis of NB4 cells (P(VP-16)=0.019, P(DNR)=0.013, P(As2O3)=0.042).

CONCLUSION: The recombinant VEGF-C could induce angiogenesis, and may promote the proliferation and inhibit the chemotherapy-induced apoptosis of leukemic cells via VEGFR-3 signaling pathway, which might be potential target therapy for leukemia.