Restoring p53 Function in Head and Neck Squamous Cell Carcinoma to Improve Treatments

TP53 mutation is one of the most frequent genetic alterations in head and neck squamous cell carcinoma (HNSCC) and results in an accumulation of p53 protein in tumor cells. This makes p53 an attractive target to improve HNSCC therapy by restoring the tumor suppressor activity of this protein. Therapeutic strategies targeting p53 in HNSCC can be divided into three categories related to three subtypes encompassing WT p53, mutated p53 and HPV-positive HNSCC. First, compounds targeting degradation or direct inhibition of WT p53, such as PM2, RITA, nutlin-3 and CH1iB, achieve p53 reactivation by affecting p53 inhibitors such as MDM2 and MDMX/4 or by preventing the breakdown of p53 by inhibiting the proteasomal complex. Second, compounds that directly affect mutated p53 by binding it and restoring the WT conformation and transcriptional activity (PRIMA-1, APR-246, COTI-2, CP-31398). Third, treatments that specifically affect HPV+ cancer cells by targeting the viral enzymes E6/E7 which are responsible for the breakdown of p53 such as Ad-E6/E7-As and bortezomib. In this review, we describe and discuss p53 regulation and its targeting in combination with existing therapies for HNSCC through a new classification of such cancers based on p53 mutation status and HPV infection.

NPC-Exosome Carry Wild and Mutant-type p53 among Nasopharyngeal Cancer Patients

BACKGROUND: Nasopharyngeal cancer (NPC) is known to release a specific exosome. NPC-derived exosome (NPC-Exo) could carry p53. However, information regarding the type of p53 carrier on NPC-Exo remains limited. This study aims to introduce our important findings regarding the type of p53 NPC-Exo cargo.METHODS: Serum from patients with NPC were prepared for exosome isolation with Seramir Exoquick by following the manual instructions. RT-PCR was conducted to determine the expression levels of latent membrane protein 1 (LMP-1) and p53 in the exosome isolate. Partial sequencing of p53 amplicon was conducted to determine mutation type of p53.RESULTS: There were 8 patients enrolled in this study. According to RT-PCR results, the expression levels of LMP-1 and p53 varied in the NPC-Exo isolate. Based on sequencing analysis, 1 case of p53 mutation was noticeable.CONCLUSION: According to current results, the NPC-derived exosome potentially carries not only wild type but also mutant type p53. Further research is needed to explore deeper the effect of the mutant type p53 as an exosome carrier in the clinical application.KEYWORDS: Nasopharyngeal cancer, exosome, p53, mutation

Molecular Evaluation of Endometrial Dedifferentiated Carcinoma, Endometrioid Carcinoma, Carcinosarcoma, and Serous Carcinoma Using a Custom-Made Small Cancer Panel

It is often difficult to histologically differentiate among endometrial dedifferentiated carcinoma (DC), endometrioid carcinoma (EC), serous carcinoma (SC), and carcinosarcoma (CS) due to the presence of solid components. In this study, we aimed to categorize these carcinomas according to The Cancer Genome Atlas (TCGA) classification using a small custom-made cancer genome panel (56 genes and 17 microsatellite regions) for integrated molecular diagnosis. A total of 36 endometrial cancer cases with solid components were assessed using IHC, next-generation sequencing (NGS), and the custom-made panel. Among 19 EC cases, six were categorized as MMR-deficient (MMR-d) and eight were classified as having a nonspecific molecular profile. Three EC cases were classified as POLE mutation (POLEmut)-type, which had a very high tumor mutation burden (TMB) and low microsatellite instability (MSI). Increased TMB and MSI were observed in all three DC cases, classified as MMR-d with mutations in MLH1 and POLD1. Except for one case classified as MMR-d, all SC cases exhibited TP53 mutations and were classified as p53 mutation-type. SC cases also exhibited amplification of CCND1, CCNE1, and MYC. CS cases were classified as three TCGA types other than the POLEmut-type. The IHC results for p53 and ARID1A were almost consistent with their mutation status. NGS analysis using a small panel enables categorization of endometrial cancers with solid proliferation according to TCGA classification. As TCGA molecular classification does not consider histological findings, an integrated analytical procedure including IHC and NGS may be a practical diagnostic tool for endometrial cancers.

Identification of a Mimicry of the Protein that Potentially Isolates the Mutated p53 Material and Prevents Further Protein Accumulation

The team first screened a set of protein mimics originally designed to target Alzheimer's disease and type 2 diabetes. The results identify a mimicry of the protein that potentially isolates the mutated p53 material and prevents further protein accumulation. The researchers then showed that segregation of mutated p53 grains by protein mimicking restored the suppressive function of the p53 tumor, leading to the death of a wide range of cancer cells. Importantly, protein mimicry therapy effectively reduces tumors that contain mutated p53 while showing no significant toxins for healthy tissue, resulting in significantly longer survival. "As the prevalence of cancer increases worldwide, there is an urgent need for new cancer therapies to complement or replace existing therapies," said the study's lead author. Here we show the first successful use of a small molecule amyloid inhibitor as an anticancer agent. We believe that this will have a far-reaching impact, as it effectively bridges the gap between amyloid disease and cancer and is the basis for passing on information approaches in the design of new and robust cancer mutation therapies for the p53 mutation. Keywords: Cancer; Cells; Tissues; Tumors; Prevention; Prognosis; Diagnosis; Imaging; Screening, Treatment; Management

Efficient Generation of P53 Biallelic Mutations in Diannan Miniature Pigs Using RNA-Guided Base Editing

The base editing 3 (BE3) system, a single-base gene editing technology developed using CRISPR/Cas9n, has a broad range of applications for human disease model construction and gene therapy, as it is highly efficient, accurate, and non-destructive. P53 mutations are present in more than 50% of human malignancies. Due to the similarities between humans and pigs at the molecular level, pig models carrying P53 mutations can be used to research the mechanism of tumorigenesis and improve tumor diagnosis and treatment. According to pathogenic mutations of the human P53 gene at W146* and Q100*, sgRNAs were designed to target exon 4 and exon 5 of the porcine P53 gene. The target editing efficiencies of the two sgRNAs were 61.9% and 50.0%, respectively. The editing efficiency of the BE3 system was highest (about 60%) when C (or G) was at the 5th base. Puromycin screening revealed that 75.0% (21/28) and 68.7% (22/32) of cell colonies contained a P53 mutation at sgRNA-Exon5 and sgRNA-Exon4, respectively. The reconstructed embryos from sgRNA-Exon5-5# were transferred into six recipient gilts, all of which aborted. The reconstructed embryos from sgRNA-Exon4-7# were transferred into 6 recipient gilts, 3 of which became pregnant, resulting in 14 live and 3 dead piglets. Sequencing analyses of the target site confirmed 1 P53 monoallelic mutation and 16 biallelic mutations. The qPCR analysis showed that the P53 mRNA expression level was significantly decreased in different tissues of the P53 mutant piglets (p < 0.05). Additionally, confocal microscopy and western blot analysis revealed an absence of P53 expression in the P53 mutant fibroblasts, livers, and lung tissues. In conclusion, a porcine cancer model with a P53 point mutation can be obtained via the BE3 system and somatic cell nuclear transfer (SCNT).

Sex- and Mutation-Specific p53 Gain-of-Function Activity in Gliomagenesis

In cancer, missense mutations in the DNA-binding domain of TP53 are common. They abrogate canonical p53 activity and frequently confer gain-of-oncogenic function (GOF) through localization of transcriptionally active mutant p53 to noncanonical genes. We found that several recurring p53 mutations exhibit a sex difference in frequency in patients with glioblastoma (GBM). In vitro and in vivo analysis of three mutations, p53R172H, p53Y202C, and p53Y217C, revealed unique interactions between cellular sex and p53 GOF mutations that determined each mutation's ability to transform male versus female primary mouse astrocytes. These phenotypic differences were correlated with sex- and p53 mutation–specific patterns of genomic localization to the transcriptional start sites of upregulated genes belonging to core cancer pathways. The promoter regions of these genes exhibited a sex difference in enrichment for different transcription factor DNA-binding motifs. Together, our data establish a novel mechanism for sex-specific mutant p53 GOF activity in GBM with implications for all cancer. Significance: Sex differences in cancer, including glioblastoma, have been observed in both incidence and outcome. We reveal that TP53, the most commonly mutated gene in cancer, contributes to sex differences through differential GOF activity. This discovery has critical implications for our understanding of p53 mutations and the importance of sex as a biological variable.

p53 Missense Mutation is Associated with Immune Cell PD-L1 Expression in Triple-negative Breast Cancer

BackgroundImmunotherapy is an important treatment for triple-negative breast cancer (TNBC). The programmed death ligand 1 (PD-L1) is a pivotal biomarker in TNBC, and its expression is closely related to immunotherapy response. Therefore, the association of p53 expression and mutation and PD-L1 expression was explored. Methods and Results PD-L1 expression and p53 mutation and expression were evaluated by immunohistochemistry. PD-L1 expression and expression levels between p53 mutation (missense and nonsense) and wild type; no-expression/loss vs. expression; and missense vs. nonsense groups were compared. PD-L1 expression was found mainly in tumor-infiltrating immune cells (ICs) in TNBC. Positive PD-L1 expression was associated with a high Ki67 index. There was a significant association between p53 mutation, especially missense mutation and higher histological grade, and PD-L1 expression in ICs. Compared with p53 nonsense mutation, cases with missense mutations tended to display more PD-L1 positive ICs. However, PD-L1 expression in ICs was not significantly different between the p53 mutation and expression groups. Conclusionsp53 missense mutation is partially involved in the regulatory expression of PD-L1. Both p53 missense mutation and PD-L1 expression may be potential targets for improving immunotherapy response in TNBC.

Targeting the Prion-Like Aggregation of Mutant p53 to Combat Cancer

The team first screened a set of protein mimics originally designed to target Alzheimer's disease and type 2 diabetes. The results identify a mimicry of the protein that potentially isolates the mutated p53 material and prevents further protein accumulation. The researchers then showed that segregation of mutated p53 grains by protein mimicking restored the suppressive function of the p53 tumor, leading to the death of a wide range of cancer cells. Importantly, protein mimicry therapy effectively reduces tumors that contain mutated p53 while showing no significant toxins for healthy tissue, resulting in significantly longer survival. "As the prevalence of cancer increases worldwide, there is an urgent need for new cancer therapies to complement or replace existing therapies," said the study's lead author. Here we show the first successful use of a small molecule amyloid inhibitor as an anticancer agent. We believe that this will have a far-reaching impact, as it effectively bridges the gap between amyloid disease and cancer and is the basis for passing on information approaches in the design of new and robust cancer mutation therapies for the p53 mutation. Keywords: Cancer; Cells; Tissues, Tumors; Prevention, Prognosis; Diagnosis; Imaging; Screening; Treatment; Management

Akt inhibitor augments anti-proliferative efficacy of a dual mTORC1/2 inhibitor by FOXO3a activation in p53 mutated hepatocarcinoma cells

Hepatocellular carcinoma (HCC) is one of the most common malignancy-related deaths. p53 mutation in HCC associates with worse clinicopathologic features including therapeutic limitation. A combination of targeted therapy may have some advantages. Akt/mTOR signaling contributes to the regulation of cell proliferation and cell death. Akt inhibitor (AZD5363) and mTORC1/2 dual inhibitor (AZD8055) are in a clinical trial for HCC and other cancers. In this study, we examined whether these inhibitors successfully induce antiproliferative activity in p53 mutant HCC cells, and the underlying mechanisms. We observed that a combination of AZD5363 and AZD8055 treatment synergizes antiproliferative activity on p53 mutated or wild-type HCC cell lines and induces apoptotic cell death. Mechanistic insights indicate that a combination of AZD5363 and AZD8055 activated FOXO3a to induce Bim-associated apoptosis in p53 mutated HCC cells, whereas cells retaining functional p53 enhanced Bax. siRNA-mediated knock-down of Bim or Bax prevented apoptosis in inhibitor-treated cells. We further observed a combination of treatment inhibits phosphorylation of FOXO3a and protects FOXO3a from MDM2 mediated degradation by preventing the phosphorylation of Akt and SGK1. FOXO3a accumulates in the nucleus under these conditions and induces Bim transcription in p53 mutant HCC cells. Combination treatment in the HCC cells expressing wild-type p53 causes interference of FOXO3a function for direct interaction with functional p53 and unable to induce Bim-associated cell death. On the other hand, Bim-associated cell death occurs in p53 mutant cells due to uninterrupted FOXO3a function. Overall, our findings suggested that a combined regimen of dual mTORC1/2 and Akt inhibitors may be an effective therapeutic strategy for HCC patients harboring p53 mutation.