Inhibition of the aryl hydrocarbon receptor/polyamine biosynthesis axis suppresses multiple myeloma
Anna Bianchi-Smiraglia, Archis Bagati, Emily E. Fink, Hayley C. Affronti, Brittany C. Lipchick, Sudha Moparthy, Mark D. Long, Spencer R. Rosario, Shivana M. Lightman, Kalyana Moparthy, David W. Wolff, Dong Hyun Yun, Zhannan Han, Anthony Polechetti, Matthew V. Roll, Ilya I. Gitlin, Katerina I. Leonova, Aryn M. Rowsam, Eugene S. Kandel, Andrei V. Gudkov, P. Leif Bergsagel, Kelvin P. Lee, Dominic J. Smiraglia, Mikhail A. Nikiforov
Anna Bianchi-Smiraglia, Archis Bagati, Emily E. Fink, Hayley C. Affronti, Brittany C. Lipchick, Sudha Moparthy, Mark D. Long, Spencer R. Rosario, Shivana M. Lightman, Kalyana Moparthy, David W. Wolff, Dong Hyun Yun, Zhannan Han, Anthony Polechetti, Matthew V. Roll, Ilya I. Gitlin, Katerina I. Leonova, Aryn M. Rowsam, Eugene S. Kandel, Andrei V. Gudkov, P. Leif Bergsagel, Kelvin P. Lee, Dominic J. Smiraglia, Mikhail A. Nikiforov
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Research Article Cell biology Oncology

Inhibition of the aryl hydrocarbon receptor/polyamine biosynthesis axis suppresses multiple myeloma

Abstract

Polyamine inhibition for cancer therapy is, conceptually, an attractive approach but has yet to meet success in the clinical setting. The aryl hydrocarbon receptor (AHR) is the central transcriptional regulator of the xenobiotic response. Our study revealed that AHR also positively regulates intracellular polyamine production via direct transcriptional activation of 2 genes, ODC1 and AZIN1, which are involved in polyamine biosynthesis and control, respectively. In patients with multiple myeloma (MM), AHR levels were inversely correlated with survival, suggesting that AHR inhibition may be beneficial for the treatment of this disease. We identified clofazimine (CLF), an FDA-approved anti-leprosy drug, as a potent AHR antagonist and a suppressor of polyamine biosynthesis. Experiments in a transgenic model of MM (Vk*Myc mice) and in immunocompromised mice bearing MM cell xenografts revealed high efficacy of CLF comparable to that of bortezomib, a first-in-class proteasome inhibitor used for the treatment of MM. This study identifies a previously unrecognized regulatory axis between AHR and polyamine metabolism and reveals CLF as an inhibitor of AHR and a potentially clinically relevant anti-MM agent.

Authors

Anna Bianchi-Smiraglia, Archis Bagati, Emily E. Fink, Hayley C. Affronti, Brittany C. Lipchick, Sudha Moparthy, Mark D. Long, Spencer R. Rosario, Shivana M. Lightman, Kalyana Moparthy, David W. Wolff, Dong Hyun Yun, Zhannan Han, Anthony Polechetti, Matthew V. Roll, Ilya I. Gitlin, Katerina I. Leonova, Aryn M. Rowsam, Eugene S. Kandel, Andrei V. Gudkov, P. Leif Bergsagel, Kelvin P. Lee, Dominic J. Smiraglia, Mikhail A. Nikiforov

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Figure 4

CLF inhibits polyamines in MM cells.

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CLF inhibits polyamines in MM cells. (A) Survival distribution of patien...
(A) Survival distribution of patients with MM (GEO GSE4581, https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi), separated by AHR expression levels. The cohort consisted of 256 patients, 64 of whom were classified as “high AHR” (average expression value = 340.14) and 192 as “low AHR” (average expression value = 27.45). Statistical analysis was performed with a log-rank test. (B) Cell extracts of the human MM cells MM.1S, RPMI-8226, and U266 were probed by immunoblotting with the indicated antibodies. (C) Cell extracts as in B were treated for 2 hours with 2 μM CLF and probed by immunoblotting. Quantification of band intensity was performed with ImageJ. (D) Extracts of MM.1S and 8226 cells were transduced with control shRNA (Ctrl-sh) or 2 independent shRNA against AHR (sh3 and sh4) and probed by immunoblotting with the indicated antibodies. (E) Extracts of MM.1S and 8226 cells transduced with empty vector (Ctrl) or CA-AHR were probed by immunoblotting as in D. Quantification of band intensity was performed with ImageJ. (F) Polyamine content in MM.1S and 8226 cells transduced with control or CA-AHR. Data represent the average ± SEM of 4 (MM1.S) or 2 (RPMI-8226) independent experiments. Cell proliferation of MM.1S (G) or 8226 (H) cells transduced with control or CA-AHR and treated for 48 hours with increasing concentrations of CLF. Control cells were supplemented with 10 μM spermidine and 1 mM aminoguanidine. IC50 values were determined using GraphPad Prism. Viability of MM.1S (I) or RPMI-8226 (J) cells (WT or resistant to BTZ-R) treated with the indicated drugs and doses for 24 hours. Data represent the average ± SEM of 2 experiments performed in duplicate. *P < 0.05 and **P < 0.001 compared with the untreated control, by 2-tailed Student’s t test (F, I, and J) and sum-of-squares F test with GraphPad Prism (G and H).