Purpose To study the reversal effect on multidrug resistance (MDR) by TNF-α gene combined with verapamil (VRP) or tamoxifen (TAM). Methods By using recombinant retrovirus vector, TNF-α gene was transfected into multidrug-resistant human breast cancer cell line MCF7/ADR. The TNF-α secreting cell clone MCF7/ADR-TNF was obtained by G418 screening. The integrating and secreting of TNF-α were analyzed by PCR and ELISA. MTT assay and formula"I = d/D1 + d/D2" were used to evaluate the reversal effect of multidmg resistance with TNF-α gene combined with verapamil or tamoxifen. ResultsThe level of TNF-α secreted by MCF7/ADR-TNF was 1 737 pg/ml (106cells/48 h). Compared with control,the resistance to ADR of MCF7/ADR-TNF was reversed by 1.6 times. The reversal effect produced by combination of TNF-α gene and VRP was antagonistic. The combination of TNF-α gene and TAM produced synergic effect (interaction index I = 0.64). ConclusionsTNF-α gene combined with TAM has synergic effect on reversing MDR.

OBJECTIVETo investigate the synergistic antitumor effects of combined use of p14ARF gene and 5-fluorouracil (5-Fu) in pancreatic cancer.

METHODSA human pancreatic cancer cell line PC-3 was transfected with lipofectin-mediated recombinant p14ARF gene, and was then administered with 5-Fu. Cell growth, morphological changes, cell cycle, apoptosis, and molecular changes were measured using the MTT assay, flow cytometry, RT-PCR, Western blotting, and immunocytochemical assays.

RESULTSAfter transfection of p14ARF, cell growth was obviously inhibited, resulting in an accumulation of cells in the G(1) phase. The proportion of cells in the G(1) phase was significantly increased from 58.51% to 75.92%, and in the S and G(2)/M phases decreased significantly from 20.05% to 12.60%, and from 21.44% to 11.48%, respectively, as compared with those of the control groups. PC-3/p14ARF cells that underwent 5-Fu treatment had significantly greater G(2)/M phase accumulation, from 11.48% to 53.47%. The apoptopic index was increased in PC-3/p14ARF cells from 3.64% to 19.62%. The MTT assay showed p14ARF-expressing cells were significantly more sensitive to 5-Fu (0.01 - 10 mg/L) than those devoid of p14ARF expression (P < 0.01). Western blotting showed p14ARF upregulates p53 expression.

CONCLUSIONCombined use of p14ARF gene and 5-Fu acts synergistically to inhibit pancreatic cancer cell proliferation, suggesting a new anticancer strategy.

Fluorouracil ; pharmacology ; Humans ; Pancreatic Neoplasms ; genetics ; therapy ; Transfection ; Tumor Cells, Cultured ; Tumor Suppressor Protein p14ARF ; genetics ; Tumor Suppressor Protein p53 ; genetics ; Up-Regulation ; physiology