Assessment of in vitro drug resistance of human breast cancer cells subcultured from biopsy specimens.

UNLABELLED

The low cellular yield of a breast cancer sample represents a limiting factor for in vitro chemosensitivity/chemoresistance testing. The use of in vitro serially cultured cells can help overcome this obstacle.

MATERIALS AND METHODS

In vitro drug resistance of cells cultured from mammary carcinomas by the 3T3 feeder-layer technique was tested by the MTT assay. Out of the 33 tested cultures, 9 were derived from cells obtained from true-cut biopsies of primary tumours, with sample volume less than 0.03 cm3. The cultures were treated with 6 anticancer drugs at 6-8 concentrations. The chemoresistance of cultured cells was monitored by the surviving cell fraction as a function of the drug concentration.

RESULTS

The average time to obtain a result was 28 days. The volume of an original sample had no effect on the in vitro resistance of a culture, suggesting minimal alteration of in vitro chemosensitivity of cells by their cultivation. Histopathological grade, estrogen receptor status or expression of the c-erb-B2 protein of the original tumours did not significantly correlate with the resistance of cultures. Individual drugs displayed distinct in vitro effectiveness. Paclitaxel and cisplatin were the most potent drugs. Gemcitabine, vinorelbine and mafosfamide were the least potent drugs. Doxorubicin and gemcitabine most frequently failed to completely metabolically inhibit 100% of cultured cells at any concentration.

CONCLUSION

Combination of the optimised feeder-layer cultivation technique and the MTT test permits extensive drug resistance testing from very small breast cancer samples.