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Mitochondrial p32 is upregulated in Myc expressing brain cancers and mediates glutamine addiction.

Fogal V, Babic I, Chao Y, Pastorino S, Mukthavaram R, Jiang P, Cho YJ, Pingle SC, Crawford JR, Piccioni DE, Kesari S - Oncotarget (2015)

Bottom Line: Loss of p32 in glutamine addicted glioma cells induced resistance to glutamine deprivation and imparted sensitivity to glucose withdrawal.Finally, we provide evidence that p32 expression contributes to Myc-induced glutamine addiction of cancer cells.Our findings suggest that Myc promotes the expression of p32, which is required to maintain sufficient respiratory capacity to sustain glutamine metabolism in Myc transformed cells.

View Article: PubMed Central - PubMed

Affiliation: Translational Neuro-Oncology Laboratories, Moores Cancer Center, University of California San Diego, La Jolla, CA.

ABSTRACT
Metabolic reprogramming is a key feature of tumorigenesis that is controlled by oncogenes. Enhanced utilization of glucose and glutamine are the best-established hallmarks of tumor metabolism. The oncogene c-Myc is one of the major players responsible for this metabolic alteration. However, the molecular mechanisms involved in Myc-induced metabolic reprogramming are not well defined. Here we identify p32, a mitochondrial protein known to play a role in the expression of mitochondrial respiratory chain complexes, as a critical player in Myc-induced glutamine addiction. We show that p32 is a direct transcriptional target of Myc and that high level of Myc in malignant brain cancers correlates with high expression of p32. Attenuation of p32 expression reduced growth rate of glioma cells expressing Myc and impaired tumor formation in vivo. Loss of p32 in glutamine addicted glioma cells induced resistance to glutamine deprivation and imparted sensitivity to glucose withdrawal. Finally, we provide evidence that p32 expression contributes to Myc-induced glutamine addiction of cancer cells. Our findings suggest that Myc promotes the expression of p32, which is required to maintain sufficient respiratory capacity to sustain glutamine metabolism in Myc transformed cells.

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Loss of p32 sensitizes cells to glucose withdrawal and reduces sensitivity to glutamine deprivation(A) p32 knockdown cells are more sensitive to the glycolytic inhibitor 2-DG. SF188 p32 knockdown cells were plated in low glucose media (2.5 mM) and 3mM 2-DG. After 18 h cell viability was determined by trypan blue exclusion. Data is the average of three experiments ± SD. (B) SF188 Control or p32 knockdown cells were plated in glutamine or glucose free media. Cell viability was determined by trypan blue exclusion. Each time point is the mean of three experiments ± SD. (C) Control (left) and p32 knockdown (right) SF188 cells were plated in complete media (25mM glucose and 4mM glutamine) and subsequently cultured in either complete media or media with 2mM glucose or without glutamine. Cell viability was determined at the indicated time points by FACS analysis of PI stained cells. Upper panel-Microscopic analysis of p32 knockdown and control SF188 cells after 2 days of growth in the indicated tissue culture media. The shown result is representative of three independent experiments.
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Figure 6: Loss of p32 sensitizes cells to glucose withdrawal and reduces sensitivity to glutamine deprivation(A) p32 knockdown cells are more sensitive to the glycolytic inhibitor 2-DG. SF188 p32 knockdown cells were plated in low glucose media (2.5 mM) and 3mM 2-DG. After 18 h cell viability was determined by trypan blue exclusion. Data is the average of three experiments ± SD. (B) SF188 Control or p32 knockdown cells were plated in glutamine or glucose free media. Cell viability was determined by trypan blue exclusion. Each time point is the mean of three experiments ± SD. (C) Control (left) and p32 knockdown (right) SF188 cells were plated in complete media (25mM glucose and 4mM glutamine) and subsequently cultured in either complete media or media with 2mM glucose or without glutamine. Cell viability was determined at the indicated time points by FACS analysis of PI stained cells. Upper panel-Microscopic analysis of p32 knockdown and control SF188 cells after 2 days of growth in the indicated tissue culture media. The shown result is representative of three independent experiments.

Mentions: Loss of p32 in breast cancer cells has been shown to promote a shift from OXPHOS toward aerobic glycolysis [37]. We examined the metabolic effects of p32 knockdown on SF188 glioblastoma cells. Attenuation of p32 expression in glioma cells resulted in enhanced glucose consumption and lactate production, two hallmarks of aerobic glycolysis (Fig. S2, supplementary data). Dependence of p32 knockdown cells on glycolysis was confirmed by an enhanced sensitivity to the non-metabolizable glucose analogue, 2-deoxyglucose (2DG) (Fig. 6A). Furthermore, p32 loss reduced growth and viability of glioma cells in glucose free and low glucose media respectively (Fig. 6B left panel and Fig. 6C).


Mitochondrial p32 is upregulated in Myc expressing brain cancers and mediates glutamine addiction.

Fogal V, Babic I, Chao Y, Pastorino S, Mukthavaram R, Jiang P, Cho YJ, Pingle SC, Crawford JR, Piccioni DE, Kesari S - Oncotarget (2015)

Loss of p32 sensitizes cells to glucose withdrawal and reduces sensitivity to glutamine deprivation(A) p32 knockdown cells are more sensitive to the glycolytic inhibitor 2-DG. SF188 p32 knockdown cells were plated in low glucose media (2.5 mM) and 3mM 2-DG. After 18 h cell viability was determined by trypan blue exclusion. Data is the average of three experiments ± SD. (B) SF188 Control or p32 knockdown cells were plated in glutamine or glucose free media. Cell viability was determined by trypan blue exclusion. Each time point is the mean of three experiments ± SD. (C) Control (left) and p32 knockdown (right) SF188 cells were plated in complete media (25mM glucose and 4mM glutamine) and subsequently cultured in either complete media or media with 2mM glucose or without glutamine. Cell viability was determined at the indicated time points by FACS analysis of PI stained cells. Upper panel-Microscopic analysis of p32 knockdown and control SF188 cells after 2 days of growth in the indicated tissue culture media. The shown result is representative of three independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4359224&req=5

Figure 6: Loss of p32 sensitizes cells to glucose withdrawal and reduces sensitivity to glutamine deprivation(A) p32 knockdown cells are more sensitive to the glycolytic inhibitor 2-DG. SF188 p32 knockdown cells were plated in low glucose media (2.5 mM) and 3mM 2-DG. After 18 h cell viability was determined by trypan blue exclusion. Data is the average of three experiments ± SD. (B) SF188 Control or p32 knockdown cells were plated in glutamine or glucose free media. Cell viability was determined by trypan blue exclusion. Each time point is the mean of three experiments ± SD. (C) Control (left) and p32 knockdown (right) SF188 cells were plated in complete media (25mM glucose and 4mM glutamine) and subsequently cultured in either complete media or media with 2mM glucose or without glutamine. Cell viability was determined at the indicated time points by FACS analysis of PI stained cells. Upper panel-Microscopic analysis of p32 knockdown and control SF188 cells after 2 days of growth in the indicated tissue culture media. The shown result is representative of three independent experiments.
Mentions: Loss of p32 in breast cancer cells has been shown to promote a shift from OXPHOS toward aerobic glycolysis [37]. We examined the metabolic effects of p32 knockdown on SF188 glioblastoma cells. Attenuation of p32 expression in glioma cells resulted in enhanced glucose consumption and lactate production, two hallmarks of aerobic glycolysis (Fig. S2, supplementary data). Dependence of p32 knockdown cells on glycolysis was confirmed by an enhanced sensitivity to the non-metabolizable glucose analogue, 2-deoxyglucose (2DG) (Fig. 6A). Furthermore, p32 loss reduced growth and viability of glioma cells in glucose free and low glucose media respectively (Fig. 6B left panel and Fig. 6C).

Bottom Line: Loss of p32 in glutamine addicted glioma cells induced resistance to glutamine deprivation and imparted sensitivity to glucose withdrawal.Finally, we provide evidence that p32 expression contributes to Myc-induced glutamine addiction of cancer cells.Our findings suggest that Myc promotes the expression of p32, which is required to maintain sufficient respiratory capacity to sustain glutamine metabolism in Myc transformed cells.

View Article: PubMed Central - PubMed

Affiliation: Translational Neuro-Oncology Laboratories, Moores Cancer Center, University of California San Diego, La Jolla, CA.

ABSTRACT
Metabolic reprogramming is a key feature of tumorigenesis that is controlled by oncogenes. Enhanced utilization of glucose and glutamine are the best-established hallmarks of tumor metabolism. The oncogene c-Myc is one of the major players responsible for this metabolic alteration. However, the molecular mechanisms involved in Myc-induced metabolic reprogramming are not well defined. Here we identify p32, a mitochondrial protein known to play a role in the expression of mitochondrial respiratory chain complexes, as a critical player in Myc-induced glutamine addiction. We show that p32 is a direct transcriptional target of Myc and that high level of Myc in malignant brain cancers correlates with high expression of p32. Attenuation of p32 expression reduced growth rate of glioma cells expressing Myc and impaired tumor formation in vivo. Loss of p32 in glutamine addicted glioma cells induced resistance to glutamine deprivation and imparted sensitivity to glucose withdrawal. Finally, we provide evidence that p32 expression contributes to Myc-induced glutamine addiction of cancer cells. Our findings suggest that Myc promotes the expression of p32, which is required to maintain sufficient respiratory capacity to sustain glutamine metabolism in Myc transformed cells.

Show MeSH
Related in: MedlinePlus