1. Academic Validation
  2. Functional cooperativity of p97 and histone deacetylase 6 in mediating DNA repair in mantle cell lymphoma cells

Functional cooperativity of p97 and histone deacetylase 6 in mediating DNA repair in mantle cell lymphoma cells

  • Leukemia. 2019 Jul;33(7):1675-1686. doi: 10.1038/s41375-018-0355-y.
Pratikkumar H Vekaria 1 Amar Kumar 1 Dharmalingam Subramaniam 2 Neil Dunavin 1 Anusha Vallurupalli 1 Frank Schoenen 3 Siddhartha Ganguly 1 Shrikant Anant 2 Joseph P McGuirk 1 Roy A Jensen 4 Rekha Rao 5 6
Affiliations

Affiliations

  • 1 Division of Hematologic Malignancies and Cellular Therapeutics, The University of Kansas Cancer Center, Kanas City, KS, USA.
  • 2 Department of Cancer Biology, The University of Kansas Cancer Center, Kanas City, KS, USA.
  • 3 Higuchi Biosciences Center, University of Kansas, Lawrence, KS, USA.
  • 4 Department of Pathology & Laboratory Medicine, The University of Kansas Cancer Center, Kansas City, KS, USA.
  • 5 Division of Hematologic Malignancies and Cellular Therapeutics, The University of Kansas Cancer Center, Kanas City, KS, USA. rraomanepalli@kumc.edu.
  • 6 Department of Cancer Biology, The University of Kansas Cancer Center, Kanas City, KS, USA. rraomanepalli@kumc.edu.
Abstract

p97 is an ATPase that works in concert with histone deacetylase 6 (HDAC6), to facilitate the degradation of misfolded proteins by autophagosomes. p97 has also been implicated in DNA repair and maintaining genomic stability. In this study, we determined the effect of combined inhibition of p97 and HDAC6 activities in mantle cell lymphoma (MCL) cells. We report that treatment with p97 inhibitors induces dose-dependent Apoptosis in MCL cells. The p97 Inhibitor CB-5083 induces ER stress markers GRP78 and CHOP and results in the accumulation of polyubiquitylated proteins. Co-treatment with CB-5083 and the HDAC6 Inhibitor ACY-1215 result in marked downregulation of CDK4, Cyclin D1, and BRCA1 levels without inhibiting autophagic flux. Consequently, treatment with CB-5083 accentuates DNA damage in response to treatment with ACY-1215 resulting in enhanced accumulation of H2AX-γ and synergistic Apoptosis. Furthermore, ATM loss severely impairs phosphorylation of 53BP1 following co-treatment with CB-5083 and ACY-1215 in response to gamma irradiation. Finally, co-treatment CB-5083 and ACY-1215 results in reduced tumor volumes and improves survival in Z138C and Jeko-1 xenografts in NSG mice. These observations suggest that combined inhibition of p97 and HDAC6 abrogates resolution of proteotoxic stress and impairs DNA repair mechanisms in MCL cells.

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