engleski

FTIR spectroscopy reveals lipid droplets in drug resistant laryngeal carcinoma cells

The major obstacle to the successful chemotherapy in the clinical management of human cancers is drug resistance. Cellular, molecular and physiological investigation of the mechanisms underlying drug resistance has identified multiple factors involved in this phenomenon. Unlike conventional techniques used in cellular or molecular biology, infrared spectroscopy is developing as new and more holistic approach for studying drug resistance. It yields a unique fingerprint of all molecules present in the cell (proteins, lipids, nucleic acids and other chemical species present) and gives information about their nature and quantities In our laboratory we have developed carboplatin resistant subline 7T of human laryngeal carcinoma HEp-2 cells. In our previous work we have investigated the anticancer potential of natural compound curcumin on HEp-2 and 7T cells. Although few literature data suggest that curcumin may revert drug resistance of cancer cells, we reported for the first time that drug resistant cells may be also cross resistant to curcumin. In order to shed more light on the molecular mechanism of multidrug resistance in 7T cells we used Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) spectroscopy. By comparing the spectra from parental HEp-2 and resistant 7T subline, we found in resistant cells an increase in intensity of ester vibrational bands. This implied an increase in amount of cholesteryl esters in resistant cells that was confirmed by enzymatic assay. Since cholesteryl esters are localized in lipid droplets we confirmed their existence and serum dependency with Oil Red O and Nile Red dye. Moreover, flow cytometry showed that treatment with oleic acid induces more lipid droplets in 7T compared to HEp-2 cells. We can conclude that in addition to previously determined molecular mechanisms of curcumin resistance in 7T cells, these cells exhibit increased content of cholesteryl esters and lipid droplets suggesting an alteration in their cellular metabolism as possible additional mechanism of drug resistance that needs to be further explored. Also, our results show the advantages of ATR-FTIR spectroscopy as a new promising technique in cancer research.

FTIR spectroscopy; lipid droplets; drug resistance

nije evidentirano