Presenter Status

Fellow

Abstract Type

Research

Primary Mentor

Dr. Tomoo Iwakuma

Start Date

6-5-2022 11:30 AM

End Date

6-5-2022 1:30 PM

Presentation Type

Poster Presentation

Description

Background: Accumulation of oncogenic mutant p53 (mutp53) greatly contributes to cancer progression. DNAJA1, which is a member of heat shock protein 40 (HSP40), also known as J-domain proteins (JDPs), plays a crucial role in the stabilization of misfolded forms of mutp53. Knockdown of DNAJA1 results in proteasomal degradation of misfolded mutp53, leading to tumor suppression. Currently, no HSP40/JDPs inhibitors are available in clinics.

Objectives/Goal: The goal of this study is to identify and characterize potential anti-cancer compounds which can induce mutp53 degradation by inhibiting HSP40/JDPs.

Methods/Design: To identify compounds that potentially bind to DNAJA1, we performed an in-silico docking study for the J-domain of DNAJA1, whose NMR structure is available, using the ZINC database of commercially available compounds. Identified compounds and their analogs were validated for their abilities to deplete p53 and/or DNAJA1 in cancer cells with different p53 status by western blotting and immunofluorescence.

Results: One of the top candidates, namely #7-3, effectively reduced the levels of DNAJA1 and misfolded mutp53. Also, an analog of #7-3, namely A#11, showed an even stronger activity to deplete both DNAJA1 and misfolded mutp53. Importantly, A#11 had minimal effects on the levels of wild-type p53 and DNA contact type of mutp53. Moreover, A#11 suppressed migration and filopodia formation in a mutp53-dependent manner. The docking study also predicted that three amino acids at tyrosine 7 (Y7), lysine 44 (K44), and glutamine 47 (Q47) in the J-domain are crucial for binding of A#11 to DNAJA1. Inserting missense mutations in these amino acids (Y7A, K44A, Q47A) attenuated the effects of A#11 on depleting DNAJA1 and mutp53 levels. Other HSP40/JDPs having Y7, K44 and Q47, including DNAJA2, DNAJA3, and DNAJB6 were also depleted by A#11. However, The response to A#11 was attenuated in HSP40/JDPs lacking one of these three amino acids, such as DNAJA4, DNAJB1, DNAJB2, DNAJB12, DNAJC3, and DNAJC7. Moreover, HSP40/JDPs lacking all of these three amino acids, such as DNAJC6 and DNAJC10 failed to respond to A#11.

Conclusions: Our study has identified a small compound that inhibits DNAJA1 and other HSP40/JDPs, leading to depletion of misfolded mutp53 and reduced cancer malignancy.

MeSH Keywords

HSP40/JDP; mutant p53

Share

COinS
 
May 6th, 11:30 AM May 6th, 1:30 PM

Identifying a novel HSP40/J-domain protein inhibitor that depletes mutant p53 to inhibit cancer malignancy

Background: Accumulation of oncogenic mutant p53 (mutp53) greatly contributes to cancer progression. DNAJA1, which is a member of heat shock protein 40 (HSP40), also known as J-domain proteins (JDPs), plays a crucial role in the stabilization of misfolded forms of mutp53. Knockdown of DNAJA1 results in proteasomal degradation of misfolded mutp53, leading to tumor suppression. Currently, no HSP40/JDPs inhibitors are available in clinics.

Objectives/Goal: The goal of this study is to identify and characterize potential anti-cancer compounds which can induce mutp53 degradation by inhibiting HSP40/JDPs.

Methods/Design: To identify compounds that potentially bind to DNAJA1, we performed an in-silico docking study for the J-domain of DNAJA1, whose NMR structure is available, using the ZINC database of commercially available compounds. Identified compounds and their analogs were validated for their abilities to deplete p53 and/or DNAJA1 in cancer cells with different p53 status by western blotting and immunofluorescence.

Results: One of the top candidates, namely #7-3, effectively reduced the levels of DNAJA1 and misfolded mutp53. Also, an analog of #7-3, namely A#11, showed an even stronger activity to deplete both DNAJA1 and misfolded mutp53. Importantly, A#11 had minimal effects on the levels of wild-type p53 and DNA contact type of mutp53. Moreover, A#11 suppressed migration and filopodia formation in a mutp53-dependent manner. The docking study also predicted that three amino acids at tyrosine 7 (Y7), lysine 44 (K44), and glutamine 47 (Q47) in the J-domain are crucial for binding of A#11 to DNAJA1. Inserting missense mutations in these amino acids (Y7A, K44A, Q47A) attenuated the effects of A#11 on depleting DNAJA1 and mutp53 levels. Other HSP40/JDPs having Y7, K44 and Q47, including DNAJA2, DNAJA3, and DNAJB6 were also depleted by A#11. However, The response to A#11 was attenuated in HSP40/JDPs lacking one of these three amino acids, such as DNAJA4, DNAJB1, DNAJB2, DNAJB12, DNAJC3, and DNAJC7. Moreover, HSP40/JDPs lacking all of these three amino acids, such as DNAJC6 and DNAJC10 failed to respond to A#11.

Conclusions: Our study has identified a small compound that inhibits DNAJA1 and other HSP40/JDPs, leading to depletion of misfolded mutp53 and reduced cancer malignancy.

 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.