Bcl-2 overexpression and hypoxia synergistically act to modulate vascular endothelial growth factor expression and in vivo angiogenesis in a breast carcinoma line.
We have previously demonstrated that bcl-2 overexpression enhances the metastatic potential of the MCF7 ADR human breast cancer cell line resistant to adriamycin by inducing metastasis-associated properties. To further elucidate the relationship between bcl-2 expression and the metastatic potential of the MCF7 ADR line, we evaluated whether bcl-2 could be also involved in the modulation of the angiogenic phenotype. Four bcl-2-overexpressing clones, a control transfectant clone, and the MCF7 ADR parental line were used for in vitro and in vivo experiments. Bcl-2 overexpression enhanced the synthesis of the hypoxia-stimulated VEGF protein and mRNA. Northern blot analysis demonstrated an increased VEGF mRNA expression in bcl-2-overexpressing clones, and reverse transcription-polymerase chain reaction showed higher levels of the VEGF(121) and VEGF(165) mRNA isoforms, which are the most active in eliciting angiogenesis. When incorporated into matrigel, supernatants of bcl-2-transfected cells cultured under hypoxic conditions induced an increased angiogenic response in C57BL/6 mice compared with that of control clone. Tumors from bcl-2 transfectants demonstrated increased VEGF expression and neovascularization as compared to the parental line, whereas the apoptosis in in vivo xenografts was similar in control and bcl-2 transfectants. The effect of bcl-2 on angiogenesis was not mediated by p53 protein. These results demonstrate that bcl-2 and hypoxia can act synergistically to modulate VEGF expression and the in vivo angiogenic response in the MCF7 ADR line.
Biroccio
A
A
Experimental Chemotherapy Laboratory, Regina Elena Cancer Institute, Rome, Italy.
Candiloro
A
A
Mottolese
M
M
Sapora
O
O
Albini
A
A
Zupi
G
G
Del Bufalo
D
D
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001483:Base Sequence; D001943:Breast Neoplasms / Q000098:blood supply* / Q000188:drug therapy / Q000235:genetics*; D015687:Cell Hypoxia / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D004317:Doxorubicin / Q000494:pharmacology; D004351:Drug Resistance; D016228:Endothelial Growth Factors / Q000235:genetics*; D005260:Female; D015870:Gene Expression; D019254:Genes, bcl-2; D016158:Genes, p53; D006801:Humans; D008222:Lymphokines / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic / Q000235:genetics*; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D000970:Antineoplastic Agents; D017931:DNA Primers; D016228:Endothelial Growth Factors; D008222:Lymphokines; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D004317:Doxorubicin