Mutant p53 Depletion by Novel Inhibitors for HSP40/J-Domain Proteins Derived from the Natural Compound Plumbagin

Abstract

Accumulation of missense mutant p53 (mutp53) in cancers promotes malignant progression. DNAJA1, a member of HSP40 (also known as J-domain proteins: JDPs), is shown to prevent misfolded or conformational mutp53 from proteasomal degradation. Given frequent addiction of cancers to oncogenic mutp53, depleting mutp53 by DNAJA1 inhibition is a promising approach for cancer therapy. However, there is no clinically available inhibitor for DNAJA1. Our in silico molecular docking study with a natural compound-derived small molecule library identified a plumbagin derivative, PLIHZ (plumbagin–isoniazid analog), as a potential compound binding to the J domain of DNAJA1. PLIHZ efficiently reduced the levels of DNAJA1 and several conformational mutp53 with minimal impact on DNA contact mutp53 and wild-type p53 (wtp53). An analog, called PLTFBH, which showed a similar activity to PLIHZ in reducing DNAJA1 and mutp53 levels, inhibited migration of cancer cells specifically carrying conformational mutp53, but not DNA contact mutp53, p53 null, and wtp53, which was attenuated by depletion of DNAJA1 or mutp53. Moreover, PLTFBH reduced levels of multiple other HSP40/JDPs with tyrosine 7 (Y7) and/or tyrosine 8 (Y8) but failed to deplete DNAJA1 mutants with alanine substitution of these amino acids. Our study suggests PLTFBH as a potential inhibitor for multiple HSP40/JDPs.

A unique chaperoning mechanism in Class A JDPs recognizes and stabilizes mutant p53

“…Interestingly, such a tumor-protective function was recently described for the DNAJA1 chaperone, which is a homologue of DNAJA2 bearing 67% sequence similarity. DNAJA1 depletion enhanced the degradation of mutant p53 and substantially reduced the malignant properties of cancer cells 64–67 . In light of these findings, we hypothesized that our newly identified interaction of DNAJA2 chaperones with mutant p53 variants may also stabilize and protect the mutant forms of the protein from proteasomal degradation, thus promoting its GOF cancer-associated effects 3 .…”

Targeting Heat Shock Proteins in Malignant Brain Tumors: From Basic Research to Clinical Trials

“…One of the molecules reported to bind Hsp40 was phenoxy-N-arylcetamides (IC 50 = 130 nM) that also disrupted the Hsp70-mediated luciferase refolding activity [ 141 ]. Other inhibitors were also reported, including benzylidene lactam compound (KNK437, N -formyl-3,4-methylenedioxy-benzylidene-γbutyrolactam) [ 142 ], natural compound-derived plumbagin derivate (PLIHZ, plumbagin-isoniazid analog) [ 143 ], and bioflavonoid quercetin (3,3′,4′,5,7-pentahydroxyflavon) [ 144 ]. Presumably, future preclinical trials will elucidate the therapeutic efficacy of HSP40 inhibitors in neuro-oncology.…”

Mechanistic Aspects of Biphenyl Urea-Based Analogues in Triple-Negative Breast Cancer Cell Lines

“…Destabilization of p53 can involve multiple pathways that we have started to explore. We observed that heat shock proteins, such as HSP40 and HSP90, that act as chaperones for p53 had been downregulated in treated cells. It has been shown that reduction in HSP90 releases mutated p53 and reactivates endogenous MDM2 for p53 degradation .…”

“…Among cancer patients, somatic mutations in TP53 across 20 different tissues have one of the highest frequencies, suggesting the importance of p53 misfunction in tumorogenesis. TNBC cell lines used in this study carry mutations in p53 that affect p53/DNA contact, 28 including R280 K in MDA-MB-231 cells, and R273H mutations in MDA-MB-468 cells. 29 Both of these mutations are responsible for the loss of apoptotic and tumor-suppressant activities.…”