Myxofibrosarcoma (MFS) is a rare and aggressive soft tissue sarcoma characterized by high genomic instability, resulting in high local recurrence rates and limited effective therapeutic options in advanced stages. Recent progress in cancer immunology research has encouraged investigation into the Tumor Microenvironment (TME) of sarcomas, including MFS, to identify immune-related biomarkers of prognostic and therapeutic relevance. Although data remain limited in MFS, existing evidence suggests a heterogeneous immune landscape, including: i) variable expression of immune checkpoint molecules such as Programmed Cell Death Protein 1 (PD-1) and Programmed Death-Ligand 1 (PD-L1), ii) presence of tumor-infiltrating lymphocytes, iii) alterations in antigen presentation pathways, and iv) a pronounced angiogenic signature. These findings underscore the potential role of immune biomarkers for patients’ clinical stratification and the consequent possibility of developing new immunotherapeutic strategies. This review will focus on the cellular and molecular architecture of immune infiltration, vascular remodeling, and lymphoid neogenesis, assessing their prognostic and predictive value as potential biomarkers. Finally, we will present ongoing clinical trials aimed at modulating the immune-vascular niche to inform innovative therapeutic strategies for this challenging sarcoma subtype.

The TP53 gene encodes the well-known p53 tumor suppressor protein, which plays a crucial role in preventing cancer development. Germline TP53 variants cause Li-Fraumeni Syndrome (LFS), an autosomal dominant disorder associated with early-onset cancers, including breast cancer, brain tumors, leukemias, bone cancers, and soft tissue sarcomas. Here, we described a germline TP53 variant c.671A>C, located at the penultimate nucleotide of exon 6 and predicted to result in the missense substitution p.E224A. The variant was identified in a 2-year-old child with retroperitoneal rhabdomyosarcoma and with a strong family history suggestive of LFS. Functional assays in yeast and human cells demonstrated wild type-like activity of the protein p.E224A; however, in silico splicing analysis indicated potential splice defects (e.g., SpliceAI score = 0.77). Given this discrepancy, we further investigated this variant using a minigene approach, demonstrating that it causes the skipping of exon 6, likely resulting in a frameshift and the introduction of a premature stop codon. These findings supported the classification of the TP53 germline variant c.671A>C (p.E224A) as likely pathogenic, providing a definitive molecular diagnosis for family counselling. Additionally, the present results sheds light on how certain predicted TP53 missense variants can be linked to disease mechanisms through RNA splicing disruption.

G-quadruplexes (G4s) are noncanonical, four-stranded nucleic acid structures formed in guanine-rich regions that influence many biological processes, including transcription. We previously developed a yeast-based system to study the transcriptional modulation of p53 family proteins by G4-forming sequences (G4FS) using artificial constructs. Here, motivated by the observation of genome-wide enrichment of G4FS in proximity to p53 and NF-κB response elements (REs), we examined how native combinations of G4FS and REs derived from human promoters influence the activity of p53 or NF-κB family proteins. To this end, five pairs of isogenic reporter strains were developed, and the propensity of G4FS to adopt G4 structures was confirmed by in vitro assays. Results in yeast showed that the presence of G4FS enhanced the transcriptional output of partial-function p53 mutants, p63, and p73 relative to wild-type p53, suggesting a general boost in the activity of weaker transcription factor proteins. Conversely, the effect of G4FS on transactivation by NF-κB proteins was context-dependent and mainly inhibitory. In conclusion, our findings highlight the importance of DNA topology in transcriptional regulation by both p53 and NF-κB proteins and demonstrate that the yeast-based system serves as a valuable tool for isolating the contribution of G4FS within a controlled genomic context.

In Chronic Lymphocytic Leukemia (CLL), mutations at the TP53 tumor suppressor gene are an important hallmark since they may strongly influence the therapeutic decision. PRIMA-1Met (also known as APR-246/Eprenetapopt) is a small molecule able to restore the wild-type (wt) p53 conformation to mutant p53 proteins and to stimulate apoptosis in tumor cells; in addition, it can deplete the glutathione reservoir, increasing reactive oxygen species (ROS) production. In this study, we investigated whether combining PRIMA-1Met with Sulfasalazine (SAS), a SLC7A11/xCT inhibitor, reduces CLL cell viability by targeting mutant p53 and the glutathione pathway. The results demonstrated that, in CLL cells, PRIMA-1Met did not restore the wt functions in the mutant p53 proteins, but it strongly reduced the antioxidant defense and induced cell death. PRIMA-1Met and SAS combination synergistically reduced cell survival regardless of p53 status and further impaired antioxidant capacity, especially in mutant p53 cells, linking their cytotoxic effect to redox imbalance. Thus, the association of PRIMA-1Met with drugs targeting the antioxidant response could represent a valid strategy to kill CLL cells carrying either wt or mutant p53.

Pathogenic germline variants in the TP53 gene cause Li-Fraumeni syndrome (LFS), a highly penetrant cancer predisposition disorder. Most of these variants arise from single-nucleotide variations (SNVs) in TP53 exons, causing missense mutations. However, some of these SNVs may also alter mRNA splicing, defining spliceogenic single nucleotide variants (SE-SNVs) of uncertain clinical significance. We reassessed previously classified TP53 missense variants for spliceogenic effects using SpliceAI predictions, in vitro minigene assays, and transcriptomic data from TCGA. Genotype-phenotype correlations were evaluated using clinical data from carriers of TP53 germline variants across multiple databases and registries. Among 58 identified SE-SNVs, 40 were missense and 18 synonymous. Experimental validation showed that most induce aberrant splicing events, frequently via cryptic splice site activation, leading to frameshift and premature stop codons. Several missense variants previously classified as having mild or low pathogenicity were found instead to have strong spliceogenic effects and were associated with early-onset cancers typical of LFS, suggesting that splicing alterations may override their protein-coding impact. The frequent SNV c.375G>A leading to the synonymous variant p.T125= shows intermediate severity, likely due to partial retention of normal splicing activity. Our study highlights the underestimated pathogenic potential of SE-SNVs affecting the TP53 gene. These findings underscore the importance of integrating splicing predictions, functional assays, and transcript-level analyses into TP53 variant interpretation to improve risk stratification in LFS. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Studies on TP53 variants at IAB Grenoble were supported by the ERiCAN program of the Fondation MSD Avenir (to P.H. and E.M.); A.R. and D.S. were supported by an Inserm Research Chair (Inserm Chaire de Recherche) to A.R.; C.P.K. was supported by the BMBF ADDRess program (01GM2205A) and by the Deutsche Kinderkrebsstiftung (DKS 2024.03); P.M. was supported by E.T.S. Engineering Ship Technology Pte Ltd. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study used existing public and controlled-access datasets and previously approved patient registries. Public datasets: The IARC/NCI TP53 Database (R21), COSMIC (v94), and gnomAD (v4.1.0) are publicly available resources. No ethical approval was required for their use. TCGA dataset: Controlled-access TCGA RNA-Seq data were obtained under dbGaP approval (NCI dbGaP Study Accession: phs000178.v11.p8). Use of de-identified TCGA data did not require additional ethical approval, in accordance with dbGaP and TCGA data access policies. LFS registries dataset: LFS Registry, Hannover, Germany: Ethics committee of Hannover Medical School gave ethical approval for this work. French LFS Cohort: French National Ethics Committee gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are either publicly available or contained within the manuscript and supplementary files. Public datasets were obtained from the IARC/NCI TP53 Database, COSMIC, gnomAD, and TCGA (NCI dbGaP Study Accession: phs000178.v11.p8). Data generated from minigene assays are available within the manuscript and supplementary materials.

Uveal melanoma (UM) is the most common intraocular tumor, and despite being rare, it accounts for nearly 13% of melanoma-related deaths. Indeed, patients with metastatic disease have typically survival rates of less than one year, with little improvement over the past few decades. Although TP53 mutations are uncommon in UM, recent findings highlight a dysfunctional p53 pathway in this cancer. Given its crucial role in mediating DNA damage responses, we analyzed the p53 protein functionality and downstream target activation in a panel of UM cell lines in response to standard-of-care treatments (i.e., cisplatin and proton-beam irradiation). Although most of the analyzed cells retained a wild-type p53, we observed a wide range of p53 protein stabilization and targets' activation. Recently, p53 isoforms have been recognized as modifiers of p53 activity, and their biology and functions depend on cellular context. We observed that UM cells express a broad spectrum of p53 isoforms, including Δ160p53α and Δ133p53β and the longer variants Δ40p53β and p53β. Interestingly, the down-regulation of the short p53 isoforms (Δ133/Δ160) revealed their contribution to promoting cell growth and in mitigating cell death triggered by standard-of-care therapies. Moreover, we verified the wild-type p53 status in a panel of 32 UM cases and analyzed the expression levels of p53 isoforms. Our results indicated a correlation between higher expression levels of Δ40p53α or Δ133p53γ isoforms and the development of more aggressive cancers. Our findings suggest that shorter p53 isoforms can promote cancer aggressiveness and therapy resistance, thereby providing crucial insights into UM pathogenesis.

A “watch and wait” strategy, delaying treatment until active disease manifests, is adopted for most CLL cases; however, prognostic models incorporating biomarkers have shown to be useful to predict treatment requirement. In our prospective O-CLL1 study including 224 patients, we investigated the predictive role of 513 microRNAs (miRNAs) on time to first treatment (TTFT). In the context of this study, six well-established variables (i.e., Rai stage, beta-2-microglobulin levels, IGVH mutational status, del11q, del17p, and NOTCH1 mutations) maintained significant associations with TTFT in a basic multivariable model, collectively yielding a Harrell’s C-index of 75% and explaining 45.4% of the variance in the prediction of TTFT. Concerning miRNAs, 73 out of 513 were significantly associated with TTFT in a univariable model; of these, 16 retained an independent relationship with the outcome in a multivariable analysis. For 8 of these (i.e., miR-582-3p, miR-33a-3p, miR-516a-5p, miR-99a-5p, and miR-296-3p, miR-502-5p, miR-625-5p, and miR-29c-3p), a lower expression correlated with a shorter TTFT, whereas in the remaining eight (i.e., miR-150-5p, miR-148a-3p, miR-28-5p, miR-144-5p, miR-671-5p, miR-1-3p, miR-193a-3p, and miR-124-3p), the higher expression was associated with shorter TTFT. Integrating these miRNAs into the basic model significantly enhanced predictive accuracy, raising the Harrell’s C-index to 81.1% and the explained variation in TTFT to 63.3%. Moreover, the inclusion of the miRNA scores enhanced the integrated discrimination improvement (IDI) and the net reclassification index (NRI), underscoring the potential of miRNAs to refine CLL prognostic models and providing insights for clinical decision-making. In silico analyses on the differently expressed miRNAs revealed their potential regulatory functions of several pathways, including those involved in the therapeutic responses. To add a biological context to the clinical evidence, an miRNA–mRNA correlation analysis revealed at least one significant negative correlation between 15 of the identified miRNAs and a set of 50 artificial intelligence (AI)-selected genes, previously identified by us as relevant for TTFT prediction in the same cohort of CLL patients. In conclusion, the identification of specific miRNAs as predictors of TTFT holds promise for enhancing risk stratification in CLL to predict therapeutic needs. However, further validation studies and in-depth functional analyses are required to confirm the robustness of these observations and to facilitate their translation into meaningful clinical utility.

The effect of mutations in the P53 family of transcription factors on their biological functions, including partial or complete loss of transcriptional activity, has been confirmed several times. At present, P53 family proteins showing partial loss of activity appear to be promising potential candidates for the development of novel therapeutic strategies which could restore their transcriptional activity. In this context, it is important to employ tools to precisely monitor their activity; in relation to this, non-canonical DNA secondary structures in promoters including G-quadruplexes (G4s) were shown to influence the activity of transcription factors. Here, we used a defined yeast assay to evaluate the impact of differently modeled G4 forming sequences on a panel of partial function P53 family mutant proteins. Specifically, a 22-mer G4 prone sequence (derived from the KSHV virus) and five derivatives that progressively mutate characteristic guanine stretches were placed upstream of a minimal promoter, adjacent to a P53 response element in otherwise isogenic yeast luciferase reporter strains. The transactivation ability of cancer-associated P53 (TA-P53α: A161T, R213L, N235S, V272L, R282W, R283C, R337C, R337H, and G360V) or Ectodermal Dyplasia syndromes-related P63 mutant proteins (ΔN-P63α: G134D, G134V and inR155) were tested. Our results show that the presence of G4 forming sequences can increase the transactivation ability of partial function P53 family proteins. These observations are pointing to the importance of DNA structural characteristics for accurate classification of P53 family proteins functionality in the context of the wide variety of TP53 and TP63 germline and somatic mutations.

Neuroblastoma (NB) is a paediatric cancer with noteworthy heterogeneity ranging from spontaneous regression to high-risk forms that are characterised by cancer relapse and the acquisition of drug resistance. The most-used anticancer drugs exert their cytotoxic effect by inducing oxidative stress, and long-term therapy has been demonstrated to cause chemoresistance by enhancing the antioxidant response of NB cells. Taking advantage of an in vitro model of multidrug-resistant (MDR) NB cells, characterised by high levels of glutathione (GSH), the overexpression of the oncoprotein BMI-1, and the presence of a mutant P53 protein, we investigated a new potential strategy to fight chemoresistance. Our results show that PTC596, an inhibitor of BMI-1, exerted a high cytotoxic effect on MDR NB cells, while PRIMA-1MET, a compound able to reactivate mutant P53, had no effect on the viability of MDR cells. Furthermore, both PTC596 and PRIMA-1MET markedly reduced the expression of epithelial–mesenchymal transition proteins and limited the clonogenic potential and the cancer stemness of MDR cells. Of particular interest is the observation that PTC596, alone or in combination with PRIMA-1MET and etoposide, significantly reduced GSH levels, increased peroxide production, stimulated lipid peroxidation, and induced ferroptosis. Therefore, these findings suggest that PTC596, by inhibiting BMI-1 and triggering ferroptosis, could be a promising approach to fight chemoresistance.

Non-canonical secondary structures in DNA are increasingly being revealed as critical players in DNA metabolism, including modulating the accessibility and activity of promoters. These structures comprise the so-called G-quadruplexes (G4s) that are formed from sequences rich in guanine bases. Using a well-defined transcriptional reporter system, we sought to systematically investigate the impact of the presence of G4 structures on transcription in yeast Saccharomyces cerevisiae. To this aim, different G4 prone sequences were modeled to vary the chance of intramolecular G4 formation, analyzed in vitro by Thioflavin T binding test and circular dichroism and then placed at the yeast ADE2 locus on chromosome XV, downstream and adjacent to a P53 response element (RE) and upstream from a minimal CYC1 promoter and Luciferase 1 (LUC1) reporter gene in isogenic strains. While the minimal CYC1 promoter provides basal reporter activity, the P53 RE enables LUC1 transactivation under the control of P53 family proteins expressed under the inducible GAL1 promoter. Thus, the impact of the different G4 prone sequences on both basal and P53 family protein-dependent expression was measured after shifting cells onto galactose containing medium. The results showed that the presence of G4 prone sequences upstream of a yeast minimal promoter increased its basal activity proportionally to their potential to form intramolecular G4 structures; consequently, this feature, when present near the target binding site of P53 family transcription factors, can be exploited to regulate the transcriptional activity of P53, P63 and P73 proteins.

Analyzing gene expression profiles (GEP) through artificial intelligence provides meaningful insight into cancer disease. This study introduces DeepSHAP Autoencoder Filter for Genes Selection (DSAF-GS), a novel deep learning and explainable artificial intelligence-based approach for feature selection in genomics-scale data. DSAF-GS exploits the autoencoder's reconstruction capabilities without changing the original feature space, enhancing the interpretation of the results. Explainable artificial intelligence is then used to select the informative genes for chronic lymphocytic leukemia prognosis of 217 cases from a GEP database comprising roughly 20,000 genes. The model for prognosis prediction achieved an accuracy of 86.4%, a sensitivity of 85.0%, and a specificity of 87.5%. According to the proposed approach, predictions were strongly influenced by CEACAM19 and PIGP, moderately influenced by MKL1 and GNE, and poorly influenced by other genes. The 10 most influential genes were selected for further analysis. Among them, FADD, FIBP, FIBP, GNE, IGF1R, MKL1, PIGP, and SLC39A6 were identified in the Reactome pathway database as involved in signal transduction, transcription, protein metabolism, immune system, cell cycle, and apoptosis. Moreover, according to the network model of the 3D protein-protein interaction (PPI) explored using the NetworkAnalyst tool, FADD, FIBP, IGF1R, QTRT1, GNE, SLC39A6, and MKL1 appear coupled into a complex network. Finally, all 10 selected genes showed a predictive power on time to first treatment (TTFT) in univariate analyses on a basic prognostic model including IGHV mutational status, del(11q) and del(17p), NOTCH1 mutations, β2-microglobulin, Rai stage, and B-lymphocytosis known to predict TTFT in CLL. However, only IGF1R [hazard ratio (HR) 1.41, 95% CI 1.08-1.84, P=0.013), COL28A1 (HR 0.32, 95% CI 0.10-0.97, P=0.045), and QTRT1 (HR 7.73, 95% CI 2.48-24.04, P<0.001) genes were significantly associated with TTFT in multivariable analyses when combined with the prognostic factors of the basic model, ultimately increasing the Harrell's c-index and the explained variation to 78.6% (versus 76.5% of the basic prognostic model) and 52.6% (versus 42.2% of the basic prognostic model), respectively. Also, the goodness of model fit was enhanced (χ2 = 20.1, P=0.002), indicating its improved performance above the basic prognostic model. In conclusion, DSAF-GS identified a group of significant genes for CLL prognosis, suggesting future directions for bio-molecular research.

Supplementary Figure S1; Supplementary Tables S1-S3.

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.

Background and aim of the study: Mutations in the G alpha-genes GNAQ and GNA11 are found in 85-90% of uveal melanomas (UM). Aim of the study is to understand whether the mutations in both genes differentially affect tumor characteristics and outcome and if so, to identify potential mechanisms. Methods: We analyzed the association between GNAQ and GNA11 mutations with disease specific survival, gene expression profiles, and cytogenetic alterations in 219 UMs. We used tandem-affinity-purification, mass spectrometry and immunoprecipitation to identify protein interaction partners of the two G-proteins and analyzed their impact on DNA-methylation. Results: GNA11 mutation was associated with: i) an increased frequency of loss of BRCA1- associated protein 1 (BAP1) expression (p = 0.0005), ii) monosomy of chromosome 3 (p < 0.001), iii) amplification of chr8q (p = 0.038), iv) the combination of the latter two (p = 0.0002), and inversely with v) chr6p gain (p = 0.003). Our analysis also showed a shorter disease-specific survival of GNA11-mutated cases as compared to those carrying a GNAQ mutation (HR = 1.97 [95%CI 1.12-3.46], p = 0.02). GNAQ and GNA11 encoded G-proteins have different protein interaction partners. Specifically, the Tet Methylcytosine Dioxygenase 2 (TET2), a protein that is involved in DNA demethylation, physically interacts with the GNAQ protein but not with GNA11, as confirmed by immunoprecipitation analyses. High risk UM cases show a clearly different DNA-methylation pattern, suggesting that a different regulation of DNA methylation by the two G-proteins might convey a different risk of progression. Conclusions: GNA11 mutated uveal melanoma has worse prognosis and is associated with high risk cytogenetic, mutational and molecular tumor characteristics that might be determined at least in part by differential DNA-methylation. (C) 2022 Elsevier Ltd. All rights reserved.

Abstract Chronic lymphocytic leukemia (CLL) cells express the interleukin-23 receptor (IL-23R) chain, but the expression of the complementary IL-12Rβ1 chain requires cell stimulation via surface CD40 molecules (and not via the B-cell receptor [BCR]). This stimulation induces the expression of a heterodimeric functional IL-23R complex and the secretion of IL-23, initiating an autocrine loop that drives leukemic cell expansion. Based on the observation in 224 untreated Binet stage A patients that the cases with the lowest miR-146b-5p concentrations had the shortest time to first treatment (TTFT), we hypothesized that miR-146b-5p could negatively regulate IL-12Rβ1 side chain expression and clonal expansion. Indeed, miR-146b-5p significantly bound to the 3′-UTR region of the IL-12Rβ1 mRNA in an in vitro luciferase assay. Downregulation of miR-146b-5p with specific miRNA inhibitors in vitro led to the upregulation of the IL-12Rβ1 side chain and expression of a functional IL-23R complex similar to that observed after stimulation of the CLL cell through the surface CD40 molecules. Expression of miR-146b-5p with miRNA mimics in vitro inhibited the expression of the IL-23R complex after stimulation with CD40L. Administration of a miR-146b-5p mimic to NSG mice, successfully engrafted with CLL cells, caused tumor shrinkage, with a reduction of leukemic nodules and of IL-12Rβ1–positive CLL cells in the spleen. Our findings indicate that IL-12Rβ1 expression, a crucial checkpoint for the functioning of the IL-23 and IL-23R complex loop, is under the control of miR-146b-5p, which may represent a potential target for therapy since it contributes to the CLL pathogenesis. This trial is registered at www.clinicaltrials.gov as NCT00917540.

Chronic lymphocytic leukemia (CLL) is a hematological disorder with complex clinical and biological behavior. TP53 mutational status and cytogenetic assessment of the deletion of the corresponding locus (17p13.1) are considered the most relevant biomarkers associated with pharmaco-predictive response, chemo-refractoriness, and worse prognosis in CLL patients. The implementation of Next Generation Sequencing (NGS) methodologies in the clinical laboratory allows for comprehensively analyzing the TP53 gene and detecting mutations with allele frequencies ≤10%, that is, "subclonal mutations". We retrospectively studied TP53 gene mutational status by NGS in 220 samples from 171 CLL patients. TP53 mutations were found in 60/220 (27.3%) samples and 47/171 (27.5%) patients. Interestingly, subclonal mutations could be detected in 31/60 samples (51.7%) corresponding to 25 patients (25/47, 53.2%). We identified 44 distinct subclonal TP53 mutations clustered in the central DNA-binding domain of p53 protein (exons 5-8, codons 133-286). Missense mutations were predominant (>80%), whereas indels, nonsense, and splice site variants were less represented. All subclonal TP53 variants but one [p.(Pro191fs)] were already described in NCI and/or Seshat databases as "damaging" and/or "probably damaging" mutations (38/44, 86% and 6/44, 14%, respectively). Longitudinal samples were available for 37 patients. Almost half of them displayed at least one TP53 mutant subclone, which could be alone (4/16, 25%) or concomitant with other TP53 mutant clonal ones (12/16, 75%); different patterns of mutational dynamics overtimes were documented. In conclusion, utilization of NGS in our "real-life" cohort of CLL patients demonstrated an elevated frequency of subclonal TP53 mutations. This finding indicates the need for precisely identifying these mutations during disease since the clones carrying them may become predominant and be responsible for therapy failures.

The TP53 tumor suppressor gene is one of the most studied gene in virtue of its ability to prevent cancer development by regulating apoptosis, cell cycle arrest, DNA repair, autophagy and senescence. Furthermore, the modulation of metabolism by P53 is fundamental for tumor suppressor activity. Studies in mouse models showed that mice carrying TP53 mutations affecting the acetylation in the DNA binding domain still retain the ability to transactivate genes involved in metabolism. Noteworthy, mice expressing the triple 3KR or the single K117R mutant do not show early on-set tumor development in contrast to TP53 −/− mice. Interestingly, the mouse K117R mutation corresponds to the human tumor-derived K120R modification, which abrogates P53-dependent activation of apoptosis without affecting growth arrest. In this study, we investigated the property of the human P53 K120R mutant in the regulation of metabolism by analyzing the transcriptional specificity in yeast- and mammalian-based reporter assays, the metabolic phenotype associated to its expression in colon cancer HCT116 TP53−/− cells and the induction of P53 targets and proteins involved in the antioxidant response. These properties were analyzed in comparison to wild type P53 protein, the human triple mutant corresponding to mouse 3KR and the cancer hot-spot R273H mutant. We confirm the selective functionality of P53 K120R mutant, which shows a transcriptional activity on cell cycle arrest but not on apoptotic targets. Interestingly, this mutant shows a partial transactivation activity on p53 response element belonging to the metabolic target TIGAR. Moreover, we observe a significant uncoupling between oxygen consumption and ATP production associated with higher lipid peroxidation level in all P53 mutants carrying cells with respect to wild type P53 expressing cells. Noteworthy, in the absence of a pro-oxidative challenge, cells expressing K120R mutant retain a partial capacity to modulate glucose metabolism, limiting lipid peroxidation with respect to the other P53 mutants carrying cells. Lastly, especially in presence of human 3KR mutant, a high expression of proteins involved in the antioxidant response is found. However, this response does not avoid the increased lipid peroxidation, confirming that only wild type P53 is able to completely counteract the oxidative stress and relative damages.

Because of its role in the regulation of the cell cycle, DNA damage response, apoptosis, DNA repair, cell migration, autophagy, and cell metabolism, the TP53 tumor suppressor gene is a key player for cellular homeostasis. TP53 gene is mutated in more than 50% of human cancers, although its overall dysfunction may be even more frequent. TP53 mutations are detected in a lower percentage of hematological malignancies compared to solid tumors, but their frequency generally increases with disease progression, generating adverse effects such as resistance to chemotherapy. Due to the crucial role of P53 in therapy response, several molecules have been developed to re-establish the wild-type P53 function to mutant P53. PRIMA-1 and its methylated form PRIMA-1Met (also named APR246) are capable of restoring the wild-type conformation to mutant P53 and inducing apoptosis in cancer cells; however, they also possess mutant P53-independent properties. This review presents the activities of PRIMA-1 and PRIMA-1Met/APR246 and describes their potential use in hematological malignancies.