PUFAs such as GLA (n-6) or DHA (n-3) were shown to exert antitumor activity on a human neuroblastoma cell line (NCG) and its VCR-resistant subline (NCG/VCR1, 8.6-fold resistant to VCR) in vitro. The NCG/VCR1 line had markedly decreased intracellular accumulation of [3H]-VCR and an accelerated drug efflux, compared to the NCG. The cytotoxic activity of PUFAs was correlated with the generation of MDA-like products in these cells. When VCR was added simultaneously with GLA or DHA to culture medium, the cytotoxic effect of VCR was about 2-fold enhanced, accompanied by about 1.5-2.0-fold increase of intracellular [3H]-VCR in both cell lines. Fatty acid analysis of membrane phospholipids of the NCG and the NCG/VCR1 cells treated with GLA or DHA showed an increased total PUFAs and SFAs, associated with markedly decreased total MUFAs and an inverted PUFAs/MUFAs ratio. Such phospholipid modification may have altered the membrane physical properties and enhanced the VCR cytotoxicity by increasing intracellular VCR accumulation; however, these PUFAs did not affect the drug efflux sufficiently enough to overcome completely the VCR resistance in the NCG/VCR1 cells. These results indicate that PUFAs partially alleviate the VCR-resistance in human neuroblastoma cells, not directly acting on VCR-resistance mechanism(s).

Cell Division↗

PubMedDate not supplied

Gamma linolenic acid alters the cytotoxic activity of anticancer drugs on cultured human neuroblastoma cells.

Gamma linolenic acid (GLA) by itself shows anti-tumor activity on various neoplastic cells in culture. We investigated the combined effect of GLA and anticancer drugs on two human neuroblastoma cell lines. The cytotoxic effect of Vinca alkaloids such as vincristine (VCR), vindesine (VDS) and vinblastine (VBL) was about 2-fold enhanced when GLA was added simultaneously to the growth medium. On the other hand, that of platinating agents such as cisplatin (CDDP) and carboplatin (CBDCA) was inhibited by GLA supplementation. The cytotoxic activity of other anticancer agents was not affected by GLA. Pharmacokinetic studies on VCR and CDDP demonstrated that intracellular accumulation of [3H]-VCR was about 1.5-fold increased in the cells pretreated by GLA, while, on the contrary, that of CDDP was rather decreased; cellular efflux of either drug was not affected. Malon dialdehyde (MDA) formation induced by supplemented GLA was not influenced by either VCR or CDDP. These results indicate that GLA exerts differential effects on the kinetics of anticancer drugs.

Antineoplastic Agents↗