A series of genetically related cell lines that express mdr genes but differ in their ability to form tumors has been challenged with gamma-linolenate and eicosapentaenoate to verify if the sensitivity of tumorigenic mdr cells to cytotoxic PUFAs differs from the sensitivity of non-tumorigenic mdr cells.

The tumorigenic mdr cell lines were derived by transformation of their parental non-tumorigenic mdr cell line with myc and ras oncogenes. Four ras and five myc transformed cell lines were used for the estimation of clonal variability. The data as based on colony forming assays, showed that six out of nine of the tumorigenic mdr cell lines were more sensitive than the non-tumorigenic mdr cells.

These results suggest that a tumorigenic phenotype renders mdr cells more sensitive to PUFAs and that PUFA supplementation either alone or in conjunction with existing forms of cancer therapy may have significant clinical implications.