Lymphokine-activated killer cell susceptibility in epirubicin-resistant and parental human non-small cell lung cancer (NSCLC)

Cetuximab and epirubicin HCl-combined application as a possibility to treat both parental and epirubicin HCl-resistant liver cancer cells

BACKGROUND AND AIMS

Targeted chemotherapeutics such as cetuximab can cause many side effects such as skin toxicity when used in high concentrations. In addition, cancer cells can develop resistance to some of the anticancer agents during treatment. The lack of the desired success in chemotherapy and the development of resistance to chemotherapeutics, such as epirubicin HCl, suggest that there is a need for combined therapies. The combination of targeted chemotherapeutics and conventional chemotherapy drugs may lead to the emergence of new strategies in the treatment of cancer. In this study, cytotoxic, antiproliferative, cell cycle inhibitive, oxidative stress generation, and apoptotic effects and effect mechanisms of cetuximab alone and together with epirubicin HCl on parental liver cancer cells (P-Hep G2) and epirubicin HCl-resistant liver cancer cells (R-Hep G2) were investigated.

MATERIALS

Cytotoxic effects of cetuximab alone and with epirubicin-HCl on cells were determined by Cell Titer-Blue® Cell Viability and Lactate Dehydrogenase Activity tests. Cell cycle distributions and apoptosis were detected by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Cetuximab with epirubicin HCl treatment increased the cytotoxic effect on both cells. Caspase-3/7 activity increased 3 and 1.5 times in comparison with control group in P-Hep G2 and R-Hep G2 cells, respectively, after treating with cetuximab alone, whereas the increase was found to be approximately 4.7 and 2.5 times when cetuximab was treated with epirubicin HCl in P-Hep G2 and R-Hep G2 cells, respectively. Both cetuximab alone and together with epirubicin HCl treatments caused increases in Bax/Bcl-2 ratio in both cells.

DISCUSSION

Treatment of cetuximab with epirubicin HCl to P-Hep G2 and R-Hep G2 cells was found to be more effective in cytotoxic effect and inducing apoptosis comparison to cetuximab alone treatment. In addition, combination treatment showed different effects on pro-apoptotic/anti-apoptotic genes expression according to cells drug resistance properties.

A Comparative Study of the Antioxidant/Prooxidant Effects of Carvacrol and Thymol at Various Concentrations on Membrane and DNA of Parental and Drug Resistant H1299 Cells

Carvacrol and thymol, both used as flavor agents in cosmetic and food products, have prooxidant and antioxidant activities. To clarify the mechanisms of their cytotoxicity and the factors affecting their antioxidant/prooxidant activities, we investigated cell membrane and DNA damage induced by carvacrol and thymol in parental and drug-resistant human lung cancer cell lines. After 24 and 48 hour incubation periods, the cytotoxicity of carvacrol (IC50 380 and 244 μM) was found to be higher than that of thymol (IC50 497 and 266 μM) in parental cells. However, thymol showed higher cytotoxic effects in drug resistant H1299 cells for three incubation periods. Also, carvacrol and thymol, at higher concentrations, increased malondealdehyde (MDA) levels causing membrane damage and 8-hydroxy deoxyguanozine (8-OHdG) levels, causing DNA damage to both parental and drug resistant cells. On the other hand, carvacrol and thymol protected the cells against H2O2-induced cytotoxicity, and membrane and DNA damage when the cells were preincubated with these two compounds at lower concentration (<IC5o) before H2O2 incubation. These findings suggest that carvacrol and thymol exhibit protective/damaging effects depending on cell resistance, concentration and time.