Fig. 1.

Leptin and resistin impair the outcome of DTIC therapy in melanoma cells. a, b Effect of leptin (a) and resistin (b) on the outcome of DTIC in A375 cells. A375 (human melanoma) cells were plated in 96-well plates. After 24 h, cells were treated with 100 ng/ml of recombinant leptin or resistin in DMEM containing 1% FBS for 1 h. Then, cells were treated with DTIC at the indicated concentrations and incubated for 48 h. These cells were subjected to MTT assay, and IC₅₀ of DTIC was calculated. c–f Effect of ob/ob and db/db serum factors on the survival of B16F10 cells upon DTIC treatment. B16F10 cells were chronically grown in medium containing 5% serum collected from ob-WT or ob/ob mice for 15 days. These cells were then subjected to DTIC treatment at the indicated concentrations, for 48 h, and MTT assay was performed. c Survival of B16F10 cells in DMEM containing ob-WT or ob/ob serum. d Measurement of IC₅₀ values of DTIC in DMEM containing ob-WT or ob/ob serum. e, f B16F10 cells were chronically grown in medium containing 5% serum collected from db-WT or db/db mice for 15 days. These cells were then subjected to DTIC treatment at the indicated concentrations, for 48 h, and MTT assay was performed. e Survival of B16F10 cells in DMEM containing db-WT or db/db serum. f Measurement of IC₅₀ value of DTIC in DMEM containing db-WT or db/db serum. The data are representative of experiments performed three times in triplicate. The results are given as means ± standard error of the mean. All the experiments were performed three times. Statistical analysis was performed using two-tailed unpaired Student’s t test; *p < 0.05; Ctrl, control; Lep, leptin; Res, resistin