[Inhibition of hypoxia-inducible factor-1 alpha in RPMI8226 myeloma cells results in reduced tumor growth in nude mice].
OBJECTIVE
To explore the influence of inhibition of hypoxia-inducible factor-1 alpha (HIF-1 alpha) by RNA interference (RNAi) on tumorigenesis of human myeloma cell line (HMCL) RPMI8226 cells in nude mice.


METHODS
RNAi vector of HIF-1 alpha was constructed with commercial shRNA expression vector pSilencer 2. 1-U6 hygro. RT-PCR and western blot were used to detect HIF-1 alpha mRNA and protein expression respectively. Vascular endothelial growth factor (VEGF) secretion and cell cycle changes were detected by ELISA and flow cytometry respectively. Expression of target gene of HIF-1 alpha, VEGF and Glut-1 were tested under hypoxia condition. Tumorigenesis was observed after transfected cells were injected subcutaneously in nude mice.


RESULTS
After interference, expression of HIF-1 alpha decreased significantly at both mRNA and protein level. Under normoxia condition, VEGF concentrations in HIF-la inhibited cells (RPMI8226-il and RPMI8226-i2) and non-inhibited cells (RPMI8226-c and RPMI8226) showed no differences. While under hypoxia condition, VEGF concentration in the above four cells was (506.0 +/- 53.2), (494.7 +/- 63.1), (984.4 +/- 61.9) and (938.2 +/- 62.2) pg/ml, respectively, being significantly lower in RPMI8226-il and RPMI8226-i2 cells than in RPMI8226-c and RPMI8226 cells (P <0.05). HIF-1 alpha interference was found to suppress the cells shift from S-phase to G1 induced by hypoxia. VEGF and Glut-1 expressions were markedly attenuated (P <0.05). The growth rate of HIF-1 alpha inhibition tumors in subcutaneous xenograft model decreased drastically.


CONCLUSIONS
RNAi inhibits HIF-1 alpha expression. Reduced tumor growth by HIF-1 alpha inhibition may partly through inhibiton of angiogenesis and glycolysis metabolism.
Li
Bing-Zong
BZ
Department of Hematology, Second Affilliated Hospital of Soochow University, Suzhoo 215004, China.
Zhuang
Wen-Zhuo
WZ
Chen
Ping
P
Fu
Jin-Xiang
JX
D000818:Animals; D002453:Cell Cycle; D045744:Cell Line, Tumor; D005822:Genetic Vectors; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology*; D034622:RNA Interference; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
D051272:Glucose Transporter Type 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C495678:Slc2a1 protein, mouse; D042461:Vascular Endothelial Growth Factor A