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The oncogenic transcription factor c-Jun regulates glutaminase expression and sensitizes cells to glutaminase-targeted therapy.

Lukey MJ, Greene KS, Erickson JW, Wilson KF, Cerione RA - Nat Commun (2016)

Bottom Line: We show that c-Jun directly binds to the GLS promoter region, and is sufficient to increase gene expression.Furthermore, ectopic overexpression of c-Jun renders breast cancer cells dependent on GLS activity.These findings reveal a role for c-Jun as a driver of cancer cell metabolic reprogramming, and suggest that cancers overexpressing JUN may be especially sensitive to GLS-targeted therapies.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA.

ABSTRACT
Many transformed cells exhibit altered glucose metabolism and increased utilization of glutamine for anabolic and bioenergetic processes. These metabolic adaptations, which accompany tumorigenesis, are driven by oncogenic signals. Here we report that the transcription factor c-Jun, product of the proto-oncogene JUN, is a key regulator of mitochondrial glutaminase (GLS) levels. Activation of c-Jun downstream of oncogenic Rho GTPase signalling leads to elevated GLS gene expression and glutaminase activity. In human breast cancer cells, GLS protein levels and sensitivity to GLS inhibition correlate strongly with c-Jun levels. We show that c-Jun directly binds to the GLS promoter region, and is sufficient to increase gene expression. Furthermore, ectopic overexpression of c-Jun renders breast cancer cells dependent on GLS activity. These findings reveal a role for c-Jun as a driver of cancer cell metabolic reprogramming, and suggest that cancers overexpressing JUN may be especially sensitive to GLS-targeted therapies.

No MeSH data available.


Related in: MedlinePlus

c-Jun correlates strongly with GLS levels in human breast cancer cell lines.Cells were collected at ∼60% confluency from RPMI growth medium supplemented with 10% FBS, and whole-cell lysates prepared and analysed by western blot. Samples were ordered according to glutamine dependence, increasing from left to right (Supplementary Fig. 3). (a) Correlation between c-Jun/phospho-c-Jun and GLS levels. Quantification of GLS and c-Jun band intensities allowed a Pearson correlation coefficient of 0.85 to be determined (Supplementary Fig. 4a). (b) Other Jun-family members do not correlate strongly with GLS levels. (c) Under 10% FBS culture conditions, p46 JNK (lower band) is active in all of the breast cancer cell lines. Neither JNK nor phospho-JNK correlate with GLS levels. (d) Other reported regulators of GLS expression do not strongly correlate with GLS levels.
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f4: c-Jun correlates strongly with GLS levels in human breast cancer cell lines.Cells were collected at ∼60% confluency from RPMI growth medium supplemented with 10% FBS, and whole-cell lysates prepared and analysed by western blot. Samples were ordered according to glutamine dependence, increasing from left to right (Supplementary Fig. 3). (a) Correlation between c-Jun/phospho-c-Jun and GLS levels. Quantification of GLS and c-Jun band intensities allowed a Pearson correlation coefficient of 0.85 to be determined (Supplementary Fig. 4a). (b) Other Jun-family members do not correlate strongly with GLS levels. (c) Under 10% FBS culture conditions, p46 JNK (lower band) is active in all of the breast cancer cell lines. Neither JNK nor phospho-JNK correlate with GLS levels. (d) Other reported regulators of GLS expression do not strongly correlate with GLS levels.

Mentions: Because the JUN proto-oncogene is overexpressed, and associated with aggressive behaviour, in a subset of human breast cancers353637, we probed a panel of 12 breast cancer cell lines for c-Jun and GLS. First, we obtained an estimate of the glutamine dependence of each cell line by assaying proliferation over 6 days in culture medium containing either 2.0 or 0.1 mM glutamine (Supplementary Fig. 3). We then collected cells at ∼60% confluency from complete RPMI medium (10% FBS, 2 mM glutamine) and probed whole-cell lysates by western blot, with samples ordered by increasing glutamine dependence of the cell line, left to right. This revealed a very strong correlation (R=0.85) between relative levels of c-Jun and GLS (Fig. 4a and Supplementary Fig. 4a). In particular, cell lines with high endogenous c-Jun levels (BT-549, Hs 578T, MDA-MB-231 and TSE) all showed highly elevated GLS levels. The level of c-Jun also correlated very strongly with the glutamine dependence of the cell lines (R=0.83; see Supplementary Fig. 4b) and moderately strongly with their proliferation rates (R=0.63; see Supplementary Fig. 4c). The abundance of activated c-Jun, as indicated by phosphorylation at residue S73 (a JNK target residue), similarly correlated very strongly with GLS (Fig. 4a), whereas the related Jun-family transcription factors, JunB and JunD, showed less correlation (Fig. 4b). Relative levels of glutamate dehydrogenase (GLUD1/2) showed little variation among the cell lines (Supplementary Fig. 5).


The oncogenic transcription factor c-Jun regulates glutaminase expression and sensitizes cells to glutaminase-targeted therapy.

Lukey MJ, Greene KS, Erickson JW, Wilson KF, Cerione RA - Nat Commun (2016)

c-Jun correlates strongly with GLS levels in human breast cancer cell lines.Cells were collected at ∼60% confluency from RPMI growth medium supplemented with 10% FBS, and whole-cell lysates prepared and analysed by western blot. Samples were ordered according to glutamine dependence, increasing from left to right (Supplementary Fig. 3). (a) Correlation between c-Jun/phospho-c-Jun and GLS levels. Quantification of GLS and c-Jun band intensities allowed a Pearson correlation coefficient of 0.85 to be determined (Supplementary Fig. 4a). (b) Other Jun-family members do not correlate strongly with GLS levels. (c) Under 10% FBS culture conditions, p46 JNK (lower band) is active in all of the breast cancer cell lines. Neither JNK nor phospho-JNK correlate with GLS levels. (d) Other reported regulators of GLS expression do not strongly correlate with GLS levels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837472&req=5

f4: c-Jun correlates strongly with GLS levels in human breast cancer cell lines.Cells were collected at ∼60% confluency from RPMI growth medium supplemented with 10% FBS, and whole-cell lysates prepared and analysed by western blot. Samples were ordered according to glutamine dependence, increasing from left to right (Supplementary Fig. 3). (a) Correlation between c-Jun/phospho-c-Jun and GLS levels. Quantification of GLS and c-Jun band intensities allowed a Pearson correlation coefficient of 0.85 to be determined (Supplementary Fig. 4a). (b) Other Jun-family members do not correlate strongly with GLS levels. (c) Under 10% FBS culture conditions, p46 JNK (lower band) is active in all of the breast cancer cell lines. Neither JNK nor phospho-JNK correlate with GLS levels. (d) Other reported regulators of GLS expression do not strongly correlate with GLS levels.
Mentions: Because the JUN proto-oncogene is overexpressed, and associated with aggressive behaviour, in a subset of human breast cancers353637, we probed a panel of 12 breast cancer cell lines for c-Jun and GLS. First, we obtained an estimate of the glutamine dependence of each cell line by assaying proliferation over 6 days in culture medium containing either 2.0 or 0.1 mM glutamine (Supplementary Fig. 3). We then collected cells at ∼60% confluency from complete RPMI medium (10% FBS, 2 mM glutamine) and probed whole-cell lysates by western blot, with samples ordered by increasing glutamine dependence of the cell line, left to right. This revealed a very strong correlation (R=0.85) between relative levels of c-Jun and GLS (Fig. 4a and Supplementary Fig. 4a). In particular, cell lines with high endogenous c-Jun levels (BT-549, Hs 578T, MDA-MB-231 and TSE) all showed highly elevated GLS levels. The level of c-Jun also correlated very strongly with the glutamine dependence of the cell lines (R=0.83; see Supplementary Fig. 4b) and moderately strongly with their proliferation rates (R=0.63; see Supplementary Fig. 4c). The abundance of activated c-Jun, as indicated by phosphorylation at residue S73 (a JNK target residue), similarly correlated very strongly with GLS (Fig. 4a), whereas the related Jun-family transcription factors, JunB and JunD, showed less correlation (Fig. 4b). Relative levels of glutamate dehydrogenase (GLUD1/2) showed little variation among the cell lines (Supplementary Fig. 5).

Bottom Line: We show that c-Jun directly binds to the GLS promoter region, and is sufficient to increase gene expression.Furthermore, ectopic overexpression of c-Jun renders breast cancer cells dependent on GLS activity.These findings reveal a role for c-Jun as a driver of cancer cell metabolic reprogramming, and suggest that cancers overexpressing JUN may be especially sensitive to GLS-targeted therapies.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA.

ABSTRACT
Many transformed cells exhibit altered glucose metabolism and increased utilization of glutamine for anabolic and bioenergetic processes. These metabolic adaptations, which accompany tumorigenesis, are driven by oncogenic signals. Here we report that the transcription factor c-Jun, product of the proto-oncogene JUN, is a key regulator of mitochondrial glutaminase (GLS) levels. Activation of c-Jun downstream of oncogenic Rho GTPase signalling leads to elevated GLS gene expression and glutaminase activity. In human breast cancer cells, GLS protein levels and sensitivity to GLS inhibition correlate strongly with c-Jun levels. We show that c-Jun directly binds to the GLS promoter region, and is sufficient to increase gene expression. Furthermore, ectopic overexpression of c-Jun renders breast cancer cells dependent on GLS activity. These findings reveal a role for c-Jun as a driver of cancer cell metabolic reprogramming, and suggest that cancers overexpressing JUN may be especially sensitive to GLS-targeted therapies.

No MeSH data available.


Related in: MedlinePlus