OBJECTIVETo investigate the effect of 1,25-dihydroxyvitamin D(3) and 5-fluorouracil, either alone or in combination, on the expression of IGFBP-3 in human esophageal carcinoma 109 cell xenograft in nude mice.

METHODSIn vitro cultured esophageal carcinoma Eca-109 cells were inoculated subcutaneously in BALB/c mice. The tumor-bearing mice were randomly divided into control group (A), 1,25-dihydroxyvitamin D(3) group (B), 5-fluorouracil group (C), and 1,25-dihydroxyvitamin D(3) plus 5-fluorouracil group (D). 1,25-dihydroxyvitamin D(3) and 5-fluorouracil were administered at the doses of 2.5 ug/kg and 25 mg/kg via intraperitoneal injections, respectively, and the mice in the control group received saline injection only. The tumor growth was observed and the expression of IGFBP-3 in the tumor xenograft was detected using immunohistochemistry. An automatic biochemistry analyzer was used to determine serum calcium levels, and Von Kossa staining was utilized for observation of calcium deposition in the kidneys.

RESULTSCompared with that in group A, the xenograft in groups B, C, and D all showed a lowered growth rate with a smaller tumor volume, and presented with stronger IGFBP-3 positivity and significantly higher levels of IGFBP-3 protein expression (P<0.05). In group D, the protein expression of IGFBP-3 was significantly increased compared with that in groups B and C (P<0.05). Compared with that in group A, serum calcium level was slightly increased in groups B, C, and D, , but no obvious calcium deposition was found in the kidney tissue sections.

CONCLUSIONBoth 1,25-dihydroxyvitamin D(3) and 5-fluorouracil can inhibit the growth of the tumor xenograft in nude mice, and their combination is more effective. This effect is probably associated with increased protein expression of IGFBP-3 in the xenograft tumor. No calcium deposition occurs in the kidney tissue of the tumor-bearing mice.