engleski

The role of Coxsackie and adenovirus receptor in response of colon carcinoma and lung carcinoma cells to anticancer drugs

Coxsackie and adenovirus receptor (CAR) is a membrane protein that was first identified as the primary receptor for coxsackie B and adenoviruses. However, its role in normal cellular physiology is not resolved. CAR is reported to be involved in the formation of epithelial tight junctions and the maintenance of the cytoskeletal structure. ZO-1, JAML, actin and microtubule were identified as its direct partners suggesting that CAR has a role in the regulation of cellular processes through protein-protein interactions. Further investigations revealed that CAR endogenuos expression in cancer cells is reduced or loss, and that ectopically enforced CAR expression inhibits cell proliferation, invasion and metastasis. These data suggest its role as tumor supressor, although contradictory data were published as well. To the best of our knowledge, there is no literature data regarding the role of CAR in the cell response to anticancer drugs. Aiming to contribute to the elucidation of that potential role, we present the results of the experiments performed on two cell lines that constitutively express high level of CAR - colon carcinoma HCT-116 cells and lung carcinoma H460 cells. Following the reduction of CAR expression using CAR-specific small interfering RNA (siRNA), the sensivity of cells to four anti-cancer drugs with different mode of action - cisplatin, doxorubicin, mitomycin c and vincristine, was examined using spectrophotometric MTT assay. Silencing of CAR enhanced the resistance of HCT-116 cells to cisplatin, and to a lesser extent to mitomycin c and doxorubicin, but did not alter the sensitivity to vincristine. Silencing of CAR did not alter the sensitivity of H460 cells to cisplatin or doxorubicin, but increased the sensitivity to vincristine and to a lesser extent to mitomycin c. Immunocytochemistry showed that silencing of CAR did not alter its membrane localization in neither HCT-116 nor in H460 cells, but reduced its level of expression. In addition, the organization of actin cytoskeleton was unchanged, but alteration of tubulin network organization in H460 cells and to a much lesser extent in HCT-116 cells was observed: tubulin was localized more perinuclearly. The alteration in tubulin network organization could explain the increased sensitivity of CAR-silenced H460 cells to vincristin. Our data suggest that CAR has a role in the cell response to cytotoxic drugs, and that its influence is cell-type and drug-type specific.

Coxsackie and adenovirus receptor; tumor cells; anticancer drugs

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