Separation of resistance to antitumor diarylsulfonylurea agents from collateral sensitivity to mitochondrial toxins.
Compared with parental GC3/c1 human colon adenocarcinoma cells, which are diarylsulfonylurea (DSU)-sensitive cells, the DSU-resistant clone LYC5 demonstrates 4.2-, 12.8-, and 5.3- fold increase in sensitivity to the mitochondrial toxins rotenone, antimycin, and oligomycin, respectively. Studies with hybrids formed by fusion of parental GC3/c1 cells with LYC5 cells have indicated that resistance to antitumor DSUs and collateral sensitivity to mitochondrial toxins are recessive and therefore potentially linked. To examine this, we transfected a cDNA library from GC3/c1 cells, constructed in pcDNA3, into LYC5 cells. G418-resistant colonies were selected and further selected in a single step for resistance to rotenone (100 nm). Individual colonies (designated T5LR) were expanded and tested for sensitivity to mitochondrial toxins, antitumor DSU agents (LY195779 and LY186391) that demonstrate a 45-50-fold differential potency against GC3/c1, LYC5 cells, and the antimitotic agent vincristine. Results demonstrate that resistance to mitochondrial toxins rotenone, antimycin, and oligomycin can be transferred without conferring a DSU-sensitive phenotype. Furthermore, in T5LR clones, resistance to mitochondrial toxins was not associated with increased resistance to vincristine or increased P-glycoprotein expression, supporting the contention that resistance to these agents is independent of P-glycoprotein. Southern blot analysis of T5LR clones demonstrated unique integration sites for the neomycin phosphotransferase gene into genomic DNA in clones 4 and 9, indicating independent derivation. Analysis of clones 4, 6, and 9 with use of polymerase chain reaction demonstrated a cDNA insert of approximately 1.0 kilobase.
Shu
L L
LL
Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105-2794, USA.
Houghton
P J
PJ
D000968:Antimycin A / Q000031:analogs & derivatives / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001483:Base Sequence; D004351:Drug Resistance; D006801:Humans; D008928:Mitochondria / Q000187:drug effects*; D008969:Molecular Sequence Data; D009840:Oligomycins / Q000494:pharmacology; D012402:Rotenone / Q000494:pharmacology; D013453:Sulfonylurea Compounds / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000494:pharmacology
D000970:Antineoplastic Agents; D009840:Oligomycins; D013453:Sulfonylurea Compounds; D012402:Rotenone; C032456:antimycin; D014750:Vincristine; D000968:Antimycin A