Mutant P53 Protein Research Articles

Novel Therapies for De Novo or Relapsed/Refractory AML with TP53 Mutations : A Glimmer of Hope

Background: The prognosis of TP53 mutated acute myeloid leukemia (AML) is dismal. Due to their correlation with universally bad outcomes, TP53 mutations play a crucial role in risk assessment and treatment selection in 5-10% of AML cases. Traditional Therapies have shown limited response and poor overall survival (OS). With current therapy, the median OS of a patient with newly diagnosed TP53m-AML is 6-9 months, and only around 10% of patients survive three years after allogenic hematopoietic stem cell transplantation (alloHCT). We present the safety and efficacy of novel therapeutic agents that target specifically TP53 mutated AML. Materials & Method: A comprehensive literature search was performed on PubMed, Cochrane Library, Embase, and Web of Science. We used the following mesh terms and Emtree terms, "acute myeloid leukemia" OR "AML" AND "TP53 mutations" from the inception of literature till 06/01/2022. We screened 2300 articles and included articles citing novel therapies such as "Venetoclax" (VEN), "Hypomethylating agents (HMA), 5-azacytidine (5-AZA), "checkpoint inhibitors, and "MDM2 inhibitors". We extracted data for "complete response (CR), Overall Survival (OS), and Progression-free survival (PFS) and safety variables such as grade III-IV adverse events. We excluded case reports, case series, preclinical trials, single-arm studies, review articles, meta-analyses, and controlled. STATA version 14.2 was used. Results: A total of 1814 patients were included in three-phase III and eleven phase II trials. Bcl-2 inhibitors :For VEN in combination with two phase III trials incorporating 641 patients were evaluated; In both trials, encouraging remission rates were reported in de-nov or relapsed or refractory patients harboring TP53 mutations. However, the median OS was 14.7 vs 5.17 (mTP53 vs wTP53) months in the treatment group compared to 4.9 vs 9.6 (mTP53 vs wTp53) months in the control group respectively. For VEN +AZA combination group, CR rates in mTP53 patients was 55% versus 0% in AZA alone (p < 0.001). VEN with low-dose cytarabine (LDAC) had 27% CR, whereas LDAC alone had 7%. Checkpoint inhibitors such as nivolumab showed favorable responses, as in the phase II study of nivolumab in combination with azacitidine in relapsed/refractory (R/R) AML; it demonstrated acceptable toxicity and an overall response rate (ORR) of 33%. However, increased response rates were seen in HMA-naïve patients. HDAC inhibitors : In two phase II trials incorporating AZA vs AZA + entinostat, the CR was 46% vs 44% . The mOS achieved in AZA was 18 months vs. combination therapy with entinostat. In the study by Manero et al. , the combination therapy of Decitabine and valproic acid showed CR of 34% and mOS of 11.9 months. The results of other trials with respect to TP53 mutation is shown in table 1. APR-246 inhibitors: In two phase II trials combining Eprentapopt with AZA , 29 patients were enrolled and CR of 41% was achieved.Sallman et al. described a remission of 82% with a median OS of 14.7 months in Eprenetapopt + 5-AZA. The most common grade ≥ 3 hematological adverse events were anemia, neutropenia, thrombocytopenia, and leukopenia. MDM2 Inhibitors : In the MIRROS trial, a phase III trial incorporating idasanutlin + cytarabine + placebo + cytarabine in R/R AML;436 patients were enrolled. The CR was 20.3%vs 17.1%(odds ratio [OR], 1.23; 95%CI, 0.70-2.18). Common any-grade adverse events (≥ 10%incidence in any arm) were diarrhea (87.0%vs 32.9%), febrile neutropenia (52.8%vs 49.3%), and nausea (52.5%vs 31.5%). The grade ≥3 hematological and non-hematological adverse events have been reported in Table 1. Conclusion: Emerging therapies employ unique therapeutic pathways that have led to increased optimism regarding the therapeutic potential of TP53 mutations. Although the median OS remains approximately a year with these therapies, hypomethylating drugs in combination with VEN or as independent therapy demonstrated greater response rates than induction chemotherapy. Initial progress has resulted from eprenetapopt's direct targeting of mutant p53 protein, showing a favorable 82% complete response. Still a daunting challenge, a combination of these therapies may ultimately be necessary to obtain adequate and sustained responses. Participation in clinical trials for all newly diagnosed AML patients should be encouraged to promote the development of innovative therapeutics. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

INNV-06. DETECTION OF MUTANT P53 POSITIVE GLIOBLASTOMA CELLS IN CEREBROSPINAL FLUID (CSF) USING A MICROFLUIDIC BASED IMMUNOASSAY

Abstract BACKGROUND Metastatic involvement of the CSF by non-CNS neoplasms surpasses that of primary brain tumors, although conventional glioblastoma (GBM) can occasionally be identified in the CSF. Here, we apply Biocept’s CNSide test to examine a patient CSF sample with GBM, verified with an antibody against mutant p53. The p53 pathway is deregulated in 84% of glioblastoma patients and point mutations lead to expression of mutant p53 protein. METHODS A CSF sample from 65-year-old male patient, with GBM diagnosed by MRI &amp; CT, and prior identified p53 mutation on R273C by NGS was collected into Biocept’s CSF collection tubes at Providence Saint John’s Health Center. CSF-cells were incubated, 2 days post collection, with a proprietary antibody cocktail, including anti-CD9, followed with a biotinylated secondary, which enables enrichment of capture antibody labeled cells in a streptavidin coated microfluidic device. Cells were fixed and permeabilized immunofluorescence was performed against mutant p53, CD45, fluorescently labeled streptavidin, for capture antibody detection, and DAPI. Microfluidic chips were scanned and analyzed on a Bioview system. The specificity of the mutant p53 antibody was verified using the same test on tumor cells with either wildtype p53 vs various p53 mutations. RESULTS CSF analysis by the CNSide platform detected 3 tumor cells / mL. Immunofluorescence confirmed strong expression of mutant p53 protein on about 1/3 of cells identified as tumor cells. Besides the patient R273C mutation, we demonstrated detection of P223L/V274F, E285K and Q331R mutations on tumor cell lines. DISCUSSION Our work suggests that a microfluidic based GBM capture test paired with appropriate biomarkers can be used as sensitive means to detect GBM cells in CSF and may be useful for diagnostics and treatment monitoring. Further, we demonstrated the utility of a mutant p53 antibody to identify tumor cells. Technical and clinical studies are needed to substantiate this hypothesis.

Anti-cancer activity of C. cainito leaves explained using its compounds docked with p53.

Extensive research on the mutant P53 protein has identified its pivotal role in anti-apoptosis mechanisms, drug resistance, and cancer progression in OSCC. The mass spectrum revealed the pharmacologically significant bioactive compounds reported for the first time in C cainito. Molecular docking investigation has identified four potential new P53 inhibitors compared with the standard P53 inhibitors. Hence, this analysis reinforces the likelihood of anti-cancer activities in C. cainito leaves.

GOF Mutant p53 in Cancers: A Therapeutic Challenge.

Simple SummaryIn normal cells, p53 is a protein which regulates the cell cycle progression to ensure normal cell division, growth, and development. However, in cancer, changes in the p53 DNA sequence, called genetic mutation, results in the protein either losing its normal function or exhibiting advanced pro-tumorigenic functions that lead to cancer. Importantly, cancers with mutations in the p53 protein often represent ones which are more aggressive and more resistant to chemotherapy. As a result, many studies have and continue to investigate multiple ways to target mutant p53-bearing cancer using targeted therapy, gene therapy, immunotherapy, and combination therapies. Knowledge of these strategies is important in improving the overall therapeutic response of cancers with mutant p53. This review highlights new strategies and discusses the progression of such therapies.TP53 is mutated in the majority of human cancers. Mutations can lead to loss of p53 expression or expression of mutant versions of the p53 protein. These mutant p53 proteins have oncogenic potential. They can inhibit any remaining WTp53 in a dominant negative manner, or they can acquire new functions that promote tumour growth, invasion, metastasis and chemoresistance. In this review we explore some of the mechanisms that make mutant p53 cells resistant to chemotherapy. As mutant p53 tumours are resistant to many traditional chemotherapies, many have sought to explore new ways of targeting mutant p53 tumours and reinstate chemosensitivity. These approaches include targeting of mutant p53 stability, mutant p53 binding partners and downstream pathways, p53 vaccines, restoration of WTp53 function, and WTp53 gene delivery. The current advances and challenges of these strategies are discussed.

A Water-Stable and Red-Emissive Radical Cation for Mutp53 Cancer Therapy.

Compared with conventional closed-shell fluorophores, radical cations provide an opportunity for development of red-to-NIR fluorophores with small sizes and easy preparation. However, most radical cations reported in the literature suffer from poor stability in water solution and are almost non-emissive. To tackle this challenge, we herein develop a deep-red-emissive and water-stable pyrrole radical cation P⋅+ -DPA-Zn, which can be easily generated from P-DPA-Zn by air oxidation. The deep-red-emissive P⋅+ -DPA-Zn can be used for imaging-guided mitochondria-targeted delivery of Zn2+ into cancer cells to promote mutant p53 proteins degradation and abrogate mutp53-manifested gain of function, including reduced chemotherapy resistance, inhibited cancer cell migration, decreased tumor cell colony and sphere formation. The water-stable and deep-red emissive pyrrole radical cation is thus promising for cancer theranostic applications.

A Water‐Stable and Red‐Emissive Radical Cation for Mutp53 Cancer Therapy

AbstractCompared with conventional closed‐shell fluorophores, radical cations provide an opportunity for development of red‐to‐NIR fluorophores with small sizes and easy preparation. However, most radical cations reported in the literature suffer from poor stability in water solution and are almost non‐emissive. To tackle this challenge, we herein develop a deep‐red‐emissive and water‐stable pyrrole radical cation P⋅+−DPA−Zn, which can be easily generated from P−DPA−Zn by air oxidation. The deep‐red‐emissive P⋅+−DPA−Zn can be used for imaging‐guided mitochondria‐targeted delivery of Zn2+ into cancer cells to promote mutant p53 proteins degradation and abrogate mutp53‐manifested gain of function, including reduced chemotherapy resistance, inhibited cancer cell migration, decreased tumor cell colony and sphere formation. The water‐stable and deep‐red emissive pyrrole radical cation is thus promising for cancer theranostic applications.

Drugging p53 in cancer: one protein, many targets.

Mutations in the TP53 tumour suppressor gene are very frequent in cancer, and attempts to restore the functionality of p53 in tumours as a therapeutic strategy began decades ago. However, very few of these drug development programmes have reached late-stage clinical trials, and no p53-based therapeutics have been approved in the USA or Europe so far. This is probably because, as a nuclear transcription factor, p53 does not possess typical drug target features and has therefore long been considered undruggable. Nevertheless, several promising approaches towards p53-based therapy have emerged in recent years, including improved versions of earlier strategies and novel approaches to make undruggable targets druggable. Small molecules that can either protect p53 from its negative regulators or restore the functionality of mutant p53 proteins are gaining interest, and drugs tailored to specific types of p53 mutants are emerging. In parallel, there is renewed interest in gene therapy strategies and p53-based immunotherapy approaches. However, major concerns still remain to be addressed. This Review re-evaluates the efforts made towards targeting p53-dysfunctional cancers, and discusses the challenges encountered during clinical development.

76P Modulation of mutant p53 activity using indazole derivatives

Oncogenic mutation p53 Y220C is the ninth most common mutation of p53 protein. The Y220C mutation creates an expanded surface pocket in the DNA-binding domain, rapidly unfolds and denatures under physiological conditions, which effectively cancels p53 signaling and leads to the development of a tumor. In this work the novel indazole derived compounds were tested. It was found that these molecules bind to the mutated p53 protein and stabilize its structure in vitro.

Expression of Different Tumor Biomarkers in Oral Lichen Planus: A Meta-analysis

Background: Oral lichen planus (OLP) is a potentially malignant oral disorder that affects 0.5-2% of the general population with a malignant transformation rate of around 1.1%. Malignant transformation is characterized by the increased proliferation of basal layer cells under the influence of biomarkers released from the inflammatory infiltrate. This study was conducted to assess the expression of biomarkers in OLP and their possible predictive value for malignant transformation of these lesions. Methods: A search for studies on tumor biomarkers in OLP was performed in the following databases: PubMed (MEDLINE, Cochrane Library), Web of Science, and Scopus. Data were analyzed using the statistical software RevMan 5.4 (The Cochrane Collaboration, Oxford, UK). For continuous outcomes, the estimates of effects of an intervention were expressed as mean differences (MD) using the inverse variance (IV) method, and for dichotomous outcomes, the estimates of effects of an intervention were expressed as odds ratios (OR) using Mantel-Haenszel (M-H) method, all with 95% confidence intervals. Results: A total of 30 studies were included in this meta-analysis. OLP patients compared to controls without the disease had a significantly higher expression of mutated p53 protein (P&lt;0.001), Ki-67 antigen (P&lt;0.001), p16 protein (P&lt;0.001), and cell proliferation nuclear antigen (PCNA) (P=0.04), but not blc-2 protein. In contrast, OLP patients showed 3.71 times higher probability of bcl-2 protein detection (P=0.01). Conclusions: The expression of tumor biomarkers in OLP suggests the potentially malignant nature of some of these lesions

Multi-Omic Analysis of Two Common P53 Mutations: Proteins Regulated by Mutated P53 as Potential Targets for Immunotherapy.

Simple SummaryTP53 is the most frequently mutated gene in many cancers, but it has failed to be a very effective target for treatment to date. To overcome this, we have examined what else changes in cells when the TP53 gene is mutated. We modified cells that had no TP53 expression to have one of the two most common mutations, either R175H or R273H. We examined how the presence of these TP53 mutations caused cellular changes including microscopic, gene expression and peptide presentation to the immune system. This has allowed us to identify new (secondary) targets that could be used to facilitate the treatment of tumors that harbor p53 mutations.The p53 protein is mutated in more than 50% of human cancers. Mutated p53 proteins not only lose their normal function but often acquire novel oncogenic functions, a phenomenon termed mutant p53 gain-of-function. Mutant p53 has been shown to affect the transcription of a range of genes, as well as protein–protein interactions with transcription factors and other effectors; however, no one has intensively investigated and identified these proteins, or their MHC presented epitopes, from the viewpoint of their ability to act as targets for immunotherapeutic interventions. We investigated the molecular changes that occurred after the TP53 null osteosarcoma cells, SaOS-2, were transfected with one of two conformational p53-mutants, either R175H or R273H. We then examined the phenotypic and functional changes using macroscopic observations, proliferation, gene expression and proteomics alongside immunopeptidome profiling of peptide antigen presentation in the context of major histocompatibility complex (MHC) class I molecules. We identified several candidate proteins in both TP53 mutant cell lines with differential expression when compared to the TP53 null vector control, SaOS-V. Quantitative SWATH proteomics combined with immune-peptidome analysis of the class-I eluted peptides identified several epitopes presented on pMHC and in silico analysis shortlisted which antigens were expressed in a range of cancerous but not adjacent healthy tissues. Out of all the candidates, KLC1 and TOP2A showed high levels of expression in every tumor type examined. From these proteins, three A2 and four pan HLA-A epitopes were identified in both R175H and R273H from TOP2A. We have now provided a short list of future immunotherapy targets for the treatment of cancers harboring mutated TP53.

Proteasomal and autophagy-mediated degradation of mutp53 proteins through mitochondria-targeting aggregation-induced-emission materials

Close to half of human cancers harbor point mutations in the tumor-suppressor p53 gene, giving rise to the cellular accumulation of mutant p53 (mutp53) proteins with novel neomorphic gain-of-function (GOF) properties. The destruction of mutp53 proteins through either autophagic or proteasomal degradation is a viable strategy for the targeted therapy of p53-mutated cancers. Several nanomaterials, including zinc-iron and ZIF-8 nanoparticles (NPs), have been reported to induce the proteasomal degradation of mutp53 proteins. However, how autophagy, the other major cellular degradative pathway, influences NP-induced mutp53 degradation has not been investigated. This article shows that AIE-Mit-TPP, a mitochondria-targeting material with aggregation-induced emission (AIE) characteristics, elicits ubiquitination-dependent proteasomal degradation of a broad range of mutp53 proteins. Meanwhile, AIE-Mit-TPP also induces massive mitochondrial damage and autophagy. The inhibition of autophagy further increases AIE-Mit-TPP-elicited mutp53 degradation, revealing the negative impact of autophagy on AIE-Mit-TPP-induced mutp53 degradation. As expected, the degradation of mutp53 proteins by AIE-Mit-TPP abrogated mutp53-manifested GOF, leading to reductions in cell proliferation and migration and increases in cell cycle arrest and cell death. Consequently, AIE-Mit-TPP inhibited the growth of mutp53 tumors. This paper unravels the interesting interplay between the proteasomal and autophagic degradative pathways and pinpoints the modulation of autophagy as a potential strategy for optimizing NP-induced mutp53 degradation and p53-targeted cancer therapy. Statement of significanceWe have designed three different types of AIE materials: non-targeting (AIE-Br), mitochondria-targeting (AIE-Mit-TPP), lysosome-targeting (AIE-Lyso). Our results proved that mitochondria-targeting AIE material induced degradation of mutp53 proteins via the proteasome degradation pathway and abrogated mutp53-conferred GOF phenotypes. Furthermore, we performed in vitro studies on the effect of the tested materials in mutp53-expressing cancer cells and demonstrated our findings via in vivo investigations in a mouse subcutaneous p53R175H TOV112D ovarian cancer model. Our results confirmed the link between the proteasome pathway and autophagy and thus proposed a strategy of combining AIE-Mit-TPP with autophagy inhibitors for the targeted treatment of mutp53-associated tumors. Finally, we found that AIE-Mit-TPP could induce degradation of a wide-spectrum mutp53 proteins, which makes mitochondria-targeting AIE materials an effective therapeutic strategy for p53-mutated cancers.

Zinc-doped Prussian blue nanoparticles for mutp53-carrying tumor ion interference and photothermal therapy

Quite a great proportion of known tumor cells carry mutation in TP53 gene, expressing mutant p53 proteins (mutp53) missing not only original genome protective activities but also acquiring gain-of-functions that favor tumor progression and impede treatment of cancers. Zinc ions were reported as agents cytocidal to mutp53-carrying cells by recovering p53 normal functions and abrogating mutp53. Meanwhile in a hyperthermia scenario, the function of wild type p53 is required to ablate tumors upon heat treatment hence the effects might be hindered in a mutp53 background. We herein synthesized zinc-doped Prussian blue (ZP) nanoparticles (NPs) to combine Zn2+ based and photothermal therapeutic effects. An efficient release of Zn2+ in a glutathione-enriched tumor intracellular microenvironment and a prominent photothermal conversion manifested ZP NPs as zinc ion carriers and photothermal agents. Apoptotic death and autophagic mutp53 elimination were found to be induced by ZP NPs in R280K mutp53-containing MDA-MB-231 cells and hyperthermia was rendered to ameliorate the treatment in vitro through further mutp53 elimination and increased cell death. The combinatorial therapeutic effect was also confirmed in vivo in a mouse model. This study might expand zinc delivery carriers and shed a light on potential interplay of hyperthermia and mutp53 degradation in cancer treatment.

Berberine inhibits glioma cell migration and invasion by suppressing TGF-β1/COL11A1 pathway

Glioma is a clinically heterogeneous disease with a poor prognosis. Berberine (BBR), as a multi-target anti-tumor alkaloid, has the ability to penetrate the blood-brain barrier and shows cytotoxicity to glioma cells. In previous studies, we demonstrated that berberine inhibits glioma cell proliferation by inhibiting mutant p53 protein and promoting mitochondrial damage. In addition, berberine has been shown to reduce collagen accumulation in pulmonary fibrosis, diabetic nephropathy and arthritis. However, its effect on collagen in cancer needs to be further elucidated. In this study, we proved that the collagen XI alpha 1 chain (COL11A1) is highly expressed in glioma cell lines and associated with migration and invasion of glioma cells. Knocking down COL11A1 caused decreased expression of MMPs. Berberine could inhibit the migration and invasion of glioma cells by suppressing the TGF-β1/COL11A1 pathway and changes actin cytoskeleton arrangement. Nude mouse subcutaneous xenografts model also showed that berberine inhibited the expression of COL11A1 in vivo. Collectively, berberine that targets COL11A1 to inhibit glioma migration and invasion, may serve as a promising candidate for the development of anti-glioma drugs in the future.

Structural Basis of Mutation-Dependent p53 Tetramerization Deficiency

The formation of a tetrameric assembly is essential for the ability of the tumor suppressor protein p53 to act as a transcription factor. Such a quaternary conformation is driven by a specific tetramerization domain, separated from the central DNA-binding domain by a flexible linker. Despite the distance, functional crosstalk between the two domains has been reported. This phenomenon can explain the pathogenicity of some inherited or somatically acquired mutations in the tetramerization domain, including the widespread R337H missense mutation present in the population in south Brazil. In this work, we combined computational predictions through extended all-atom molecular dynamics simulations with functional assays in a genetically defined yeast-based model system to reveal structural features of p53 tetramerization domains and their transactivation capacity and specificity. In addition to the germline and cancer-associated R337H and R337C, other rationally designed missense mutations targeting a significant salt-bridge interaction that stabilizes the p53 tetramerization domain were studied (i.e., R337D, D352R, and the double-mutation R337D plus D352R). The simulations revealed a destabilizing effect of the pathogenic mutations within the p53 tetramerization domain and highlighted the importance of electrostatic interactions between residues 337 and 352. The transactivation assay, performed in yeast by tuning the expression of wild-type and mutant p53 proteins, revealed that p53 tetramerization mutations could decrease the transactivation potential and alter transactivation specificity, in particular by better tolerating negative features in weak DNA-binding sites. These results establish the effect of naturally occurring variations at positions 337 and 352 on p53’s conformational stability and function.

Statins inhibit proliferation and induce apoptosis in triple-negative breast cancer cells

TP53 (p53) is mutated in 80–90% of cases of triple-negative breast cancer (TNBC). Statins, which are widely used to treat elevated cholesterol, have recently been shown to degrade mutant p53 protein and exhibit anti-cancer activity. The aim of this work was to evaluate the potential of statins in the treatment of TNBC. The anti-proliferative effects of 2 widely used statins were investigated on a panel of 15 cell lines representing the different molecular subtypes of breast cancer. Significantly lower IC50 values were found in triple-negative (TN) than in non-TN cell lines (atorvastatin, p < 0.01; simvastatin p < 0.05) indicating greater sensitivity. Furthermore, cell lines containing mutant p53 were more responsive to both statins than cell lines expressing wild-type p53, suggesting that the mutational status of p53 is a potential predictive biomarker for statin response. In addition to inhibiting proliferation, simvastatin was also found to promote cell cycle arrest and induce apoptosis. Using an apoptosis array capable of detecting 43 apoptosis-associated proteins, a novel protein shown to be upregulated by simvastatin was the IGF-signalling modulator, IGBP4, a finding we confirmed by Western blotting. Finally, we found synergistic growth inhibition between simvastatin and the IGF-1R inhibitor, OSI-906 as well as between simvastatin and doxorubicin or docetaxel. Our work suggests repurposing of statins for clinical trials in patients with TNBC. Based on our findings, we suggest that these trials investigate statins in combination with either doxorubicin or docetaxel and include p53 mutational status as a potential predictive biomarker.

Cytoplasmic p53 aggregates accumulated in p53-mutated cancer correlate with poor prognosis.

Recent studies suggested that aggregates of mutant p53 proteins may propagate and impair normal p53 functioning in recipient cells. Our previous study showed that cancer cell-derived p53 aggregates that cells internalized interfered with p53-dependent apoptosis in recipient cells. However, involvement of p53 aggregate propagation in cancer pathology has not been fully elucidated. Here, we screened patients with high-grade serous ovarian carcinoma, which is characterized by an extremely high frequency of TP53 gene mutations, to show that patients with cytoplasmic p53 deposits have a poor prognosis compared with patients with complete p53 absence or strong nuclear p53 positivity. Cytoplasmic p53 in the patients with poor prognosis consisted of protein aggregates, which suggests that p53 aggregates are oncogenic drivers. Indeed, an inhibitor of p53 aggregation restored cellular apoptosis, a proper p53 function, in p53 aggregate-bearing patient-derived tumor organoids. In cell-based assays, endogenous and exogenous mutant p53 aggregates hindered chemotherapeutic activity of cisplatin, which depends on normal p53 functions. This inhibition was reduced by blocking p53 aggregation or internalization of p53 aggregates. Our study, thus indicates the involvement of p53 aggregate transmission in poor prognosis and in chemotherapy resistance in cancers.

Carrier-free nanoprodrug for p53-mutated tumor therapy via concurrent delivery of zinc-manganese dual ions and ROS.

Human cancers typically express a high level of tumor-promoting mutant p53 protein (Mutp53) with a minimal level of tumor-suppressing wild-type p53 protein (WTp53). In this regard, inducing Mutp53 degradation while activating WTp53 is a viable strategy for precise anti-tumor therapy. Herein, a new carrier-free nanoprodrug (i.e., Mn-ZnO2 nanoparticles) was developed for concurrent delivery of dual Zn-Mn ions and reactive oxygen species (ROS) within tumor to regulate the p53 protein for high anti-tumor efficacy. In response to the mild tumor acidic environment, the released Zn2+ and H2O2 from Mn-ZnO2 NPs induced ubiquitination-mediated proteasomal degradation of Mutp53, while the liberative Mn2+ and increased ROS level activated the ATM-p53-Bax pathway to elevate WTp53 level. Both in vitro and in vivo results demonstrated that pH-responsive decomposition of Mn-ZnO2 NPs could effectively elevate the intracellular dual Zn-Mn ions and ROS level and subsequently generate the cytotoxic hydroxyl radical (•OH) through the Fenton-like reaction. With the integration of multiple functions (i.e., carrier-free ion and ROS delivery, tumor accumulation, p53 protein modulation, toxic •OH generation, and pH-activated MRI contrast) in a single nanosystem, Mn-ZnO2 NPs demonstrate its superiority as a promising nanotherapeutics for p53-mutated tumor therapy.

Abstract 1826: Rapid and specific degradation of mutant p53 proteins by cupric diethyldithiocarbamate, the active cytotoxic component of disulfiram-copper repurposing in human cancers

Abstract Background: Disulfiram (DSF) in combination with copper pills has emerged as a safe and exciting anticancer strategy and is undergoing clinical trials in multiple human cancers. However, DSF breaks down in the gut or blood immediately and chances of cupric diethyldithiocarbamate (Cu-DDC), the active cytotoxic principle being formed at tumor sites is very low. Therefore, we have found that synthetic Cu-DDC is directly and potently cytotoxic against p53 mutant cancers. We report here for the first time the differential effects of Cu-DDC in robustly eliminating the mutant p53 proteins from tumor cells in contrast to its augmentation of the wild-type p53 protein and activation. Destabilization of Gain Of Function (GOF) p53 mutant proteins for overcoming oncogenic addiction and improving the therapeutic efficacy has been a long-sought, but unmet anticancer avenue. Methods: A panel of 7 P53 mutant cell lines (R248W, R273H,R173H), and p53 wt tumor and normal cells (HPBLs, dental pulp stem cells, IMR90 and HUVEC) were used. Immunoprecipitation, Western blotting, Annexin-V apoptotic assays, flow cytometry, immunocytochemistry were used to quantitate p53 protein. Mia-Paca2 xenografts developed in nude mice were administered Cu-DDC/BSA. Results: Cu-DDC generated peroxides but not superoxides in tumor cells. The GOF mutant p53 proteins, R248W and R273H in three different tumor cell lines were eliminated after Cu-DDC treatment in a time- and concentration-dependent manner. The loss of mutant p53 proteins was confirmed by three different procedures. The degradation occurred rapidly in 8-10 h at 100 nM Cu-DDC and was inhibited by proteasome blockers. The expression of the GRO-α oncogene, positively regulated by GOF R248W was decreased in Cu-DDC treated Mia-Paca2 cells. Cellular proteasome activity was not inhibited by Cu-DDC. Ubiquitination of mutant p53 proteins was not altered by Cu-DDC. In contrast, the wild-type p53 present in HCT116 and MCF-7 cells, and normal cell counterparts (HPBL, IMR-90 lung cells) was significantly upregulated and activated with enhanced p21cip1 expression. Cu-DDC triggered strong apoptosis irrespective of the p53 status, although the mutant p53 containing cells were 2 to 3-fold more sensitive in cytotoxicity assays (IC50 range 0.25-0.66 µM). A significant tumor growth delay accompanied by loss of mutant p53 protein was observed in MiaPaca2 xenografts. Conclusions: In moving the DSF anticancer repurposing forward, we describe the unique ability of Cu-DDC to rapidly eliminate oncogenic p53 mutant proteins and confer potent antitumor efficacy. The degradation was unrelated to the proteostasis involving the inactivation of NPL4 by Cu-DDC described previously (supported by a Cancer Prevention and Research Institute of Texas [CPRIT] grant RP170207 to KSS). Citation Format: Viswanath Arutla, Kalkunte S. Srivenugopal. Rapid and specific degradation of mutant p53 proteins by cupric diethyldithiocarbamate, the active cytotoxic component of disulfiram-copper repurposing in human cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1826.

Abstract 1295: Small molecule reactivators of Y220C mutant p53 modulate tumor infiltrating leukocytes and synergize with immune checkpoint inhibitors

Abstract Half of human cancers possess mutations in the TP53 gene, with most clustering as hotspots in the DNA binding domain. A tyrosine to cysteine substitution at amino acid 220 of the p53 protein (Y220C) is one such hotspot mutation (~1% of all solid tumors). Small molecules that reactivate Y220C mutant p53 activity to be like wild type have been developed at PMV Pharmaceuticals and the lead compound PC14586 is in Phase I clinical development. The molecules were designed to bind tightly to a crevice within the Y220C p53 mutant protein and stabilize it to a wild type conformation allowing reactivation of p53 transcriptional activity and expression of target proteins (e.g. p21, MDM2), resulting in tumor regression in Y220C p53 mutant xenograft models grown in immunocompromised mice. p53 has been documented to contribute to immune responses by activating regulators of immune signaling pathways and to result in T-cell exclusion in tumor models. To investigate the role of p53 and the immune system in tumorigenesis, a Y220C human p53 knock-in (HUPKI) mouse was generated. Mice that are homozygous mutant for the Y220C humanized alleles succumbed to lymphomas and sarcomas within 6 months and cell lines generated from these tumors were shown to be sensitive in an in vitro proliferation assay to Y220C p53 reactivators (IC50 ~ 192-722 nM) and used to generate Y220C mutant syngeneic mouse models. Administration of Y220C p53 reactivators in Y220C p53 syngeneic mouse models resulted in a dose responsive anti-tumor effect, with maximally efficacious doses resulting in durable cures in nearly all animals, more than observed in immunocompromised mouse models. Addition of checkpoint agents with sub-efficacious administration of Y220C reactivating compounds resulted in synergistic increases in mean survival time of mice, longer than with either single agent. Immunophenotyping analysis of HUPKI Y220C mutant tumors exposed to p53 reactivator compounds showed modulation of the tumor immune environment. Changes include dose responsive increases in T-cells (CD4+, CD8+), T-regulatory cells, natural killer T cells and dose responsive decreases in macrophages (M2) and g-MDSC cells. The synergy observed with an anti-PD-1 combination appears driven by an increase in CD8+ T cells, given a decrease in efficacy in mice depleted of CD8+ T cells, following exposure to anti-CD8. Further investigation into the role of Y220C p53 reactivation in immune modulation showed decreased cytokines and chemokines involved in inflammation (i.e. CXCL10, Ccl2) and an increase in a Tumor Inflammation Signature (nanoString) in a dose and time dependent manner. Taken together, these data suggest a role for p53 signaling in encouraging an immunologically hot tumor microenvironment and provide support for testing small molecule reactivators of mutant p53 in combination with immune checkpoint inhibitors. Citation Format: Anna M. Puzio-Kuter, Chris Mulligan, Brandon Russo, Amy Wiebesiek, Lizhong Xu, Hong Yang, Binh Vu, Melissa Dumble. Small molecule reactivators of Y220C mutant p53 modulate tumor infiltrating leukocytes and synergize with immune checkpoint inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1295.

Clinical significance and immunogenomic landscape analysis of glycolysis-associated prognostic model to guide clinical therapy in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a common malignant tumor with a poor prognosis and high mortality rate worldwide. Glucose metabolism disorder is one of the most important characteristics of HCC. However, as the primary risk factors for the prognosis of HCC patients are unclear, the survival prognosis and therapy response of patients cannot be accurately predicted. First, gene sets of 29 cancer hallmarks were collected from public databases. The z-score of various cancer hallmarks were quantitively analyzed by a single-sample gene set enrichment analysis (ssGSEA) of HCC patients. Next, a glycolysis-related gene signature (GRS) was constructed using a series of bioinformatics methods, which were used to predict the survival prognosis of HCC patients and the immunotherapy benefits. The prediction accuracy of the GRS was validated in different HCC cohorts and clinical subgroups. Additionally, a decision tree and nomogram were also established based on the GRS and other clinical variables. Finally, the genomic alterations and tumor immune microenvironment of the HCC patients were examined. Among the 29 cancer hallmarks, glycolysis was the most predominant risk factor for a poor prognosis in HCC. We subsequently constructed a novel GRS comprising 12 glycolysis-related genes. The high-GRS patients had a poorer survival prognosis than the low-GRS patients. The GRS exhibited a powerful ability to predict survival prognosis in different HCC cohorts and clinical feature subgroups. Additionally, the decision tree and nomogram aided in the risk stratification and prognosis evaluations of HCC patients. Further, we found that a high GRS was characterized by a severe tumor stage, pathological grade, and other clinical features. There were significant differences in the genomic alterations, immune cells, and immune checkpoints between the low- and high-GRS patients, especially in relation to the tumor protein p53 mutation and immunosuppressive cells. Notably, we also found that the GRS could be used to identify HCC patients who are more sensitive to chemotherapy and immunotherapy. In summary, the GRS may be a useful tool for predicting the prognosis and guiding the clinical therapy of HCC patients.