title: Inhibition of MCL-1 by obatoclax sensitizes Sp2/0-Ag14 hybridoma cells to glutamine deprivation-induced apoptosis.
abstract: For several cancer cell types, the lack of an adequate supply of the amino acidl-glutamine (Gln) triggers apoptosis, a phenomenon termed Gln addiction. In this report, we examined the role of the anti-apoptotic proteins of the B-cell lymphoma 2 (BCL-2) protein family in the survival of Sp2/0-Ag14 (Sp2/0) mouse hybridoma cells, a cell line that undergoes apoptosis within minutes of Gln deprivation. Western blot analysis revealed that myeloid cell leukaemia 1 (MCL-1) was expressed at much higher levels than BCL-2, B-cell lymphoma extra-large and BCL-2-like protein 2 making it the prominent pro-survival BCL-2 family member in this hybridoma. Gln deprivation triggered a progressive decrease in MCL-1 protein levels, which coincided with the decrease in Sp2/0 cell survival. Moreover, Sp2/0 cells were much more sensitive to the broad Bcl-2 homology domain-3 (BH3) mimetic obatoclax (which targets MCL-1) than to the more selective drug ABT-737 (which does not target MCL-1). Finally, we show that obatoclax sensitizes Sp2/0 cells to apoptosis following Gln starvation. All together, the data presented here reveal that modulation of the pro-survival protein MCL-1 is an important step in the sequence of events leading to the initiation of apoptosis in Gln-starved Sp2/0 cells. Cancer cells require an adequate supply ofl-glutamine for their survival. Using a mouse hybridoma cell line that is exquisitely sensitive to glutamine starvation, we show that the levels of the pro-survival BCL-2 family protein MCL-1 decrease upon glutamine starvation in a manner that correlates with the loss of cell viability. Moreover, inhibiting MCL-1 with the drug obatoclax sensitizes hybridoma cells to glutamine starvation. Thus, in some cancer cells, glutamine starvation triggers the inactivation of pro-survival proteins. Our data suggest that the combined inhibition of glutamine biosynthesis pathways and BCL-2 proteins may prove effective against some cancers.
authors.affiliation: Biomolecular Sciences Ph.D. program, Laurentian University, Sudbury, Ontario, Canada.
authors.forename: Curtis C
authors.initials: CC
authors.lastname: Harnett
authors.affiliation: Biomolecular Sciences Ph.D. program, Laurentian University, Sudbury, Ontario, Canada.
authors.forename: Abdelmuhsen
authors.initials: A
authors.lastname: Abusneina
authors.affiliation: Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada.
authors.forename: Julie
authors.initials: J
authors.lastname: Clément
authors.affiliation: Biomolecular Sciences Ph.D. program, Laurentian University, Sudbury, Ontario, Canada.|Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ontario, Canada.|Biology Department, Laurentian University, Sudbury, Ontario, Canada.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Gauthier
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005973:Glutamine / Q000172:deficiency*; D006801:Humans; D006825:Hybridomas / Q000187:drug effects*; D007211:Indoles; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000378:metabolism*; D009596:Nitrophenols / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: C501332:ABT-737; C481505:BCL2L15 protein, human; D001713:Biphenyl Compounds; D007211:Indoles; C579095:MCL1 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009596:Nitrophenols; D010879:Piperazines; D019253:Proto-Oncogene Proteins c-bcl-2; D011758:Pyrroles; D013449:Sulfonamides; D005973:Glutamine; C520962:obatoclax
keywords: MCL-1; apoptosis; glutamine; glutamine addiction; hybridoma; nutrient starvation; obatoclax