Molecularly targeted therapies for p53-mutant cancers

Enhanced pharmacological activities of AKR1C3-activated prodrug AST-3424 in cancer cells with defective DNA repair

AST-3424 is a novel and highly tumor-selective prodrug. AST-3424 is activated by AKR1C3 to release a toxic bis-alkylating moiety, AST 2660. In this study, we have investigated the essential role of DNA repair in AST-3424 mediated pharmacological activities in vitro and in vivo. We show here that AST-3424 is effective as a single therapeutic agent against cancer cells to induce cytotoxicity, DNA damage, apoptosis and cell cycle arrest at G2 phase in a dose- and AKR1C3-dependent manner in both p53-proficient H460 (RRID:CVCL_0459) and p53-deficient HT-29 cells (RRID:CVCL_0320). The combination of abrogators of G2 checkpoint with AST-3424 was only synergistic in HT-29 but not in H460 cells. The enhanced activity of AST-3424 in HT-29 cells was due to impaired DNA repair ability via the attenuation of cell cycle G2 arrest and reduced RAD51 expression. Furthermore, we utilized a BRCA2 deficient cell line and two PDX models with BRCA deleterious mutations to study the increased activity of AST-3424. The results showed that AST-3424 exhibited enhanced in vitro cytotoxicity and superior and durable in vivo anti-tumor effects in cells deficient of DNA repair protein BRCA2. In summary, we report here that when DNA repair capacity is reduced, the in vitro and in vivo activity of AST-3424 can be further enhanced, thus providing supporting evidence for the further evaluation of AST-3424 in the clinic.

The influence of a modified p53 C-terminal peptide by using a tumor-targeting sequence on cellular apoptosis and tumor treatment

The restoration of the function of p53 in tumors is a therapeutic strategy for the highly frequent mutation of the TP53 tumor suppressor gene. P460 is a wild-type peptide derived from the p53 C-terminus and has been proven to be capable of restoring the tumor suppressor function of p53. The poor accumulation of drugs in tumors is a serious hindrance to tumor treatment. For enhancing the activity of P460, the tumor-targeting sequence Arg-Gly-Asp-Arg (RGDR, C-end rule peptide) was introduced into the C-terminus of P460 to generate the new peptide P462. P462 presented better activity than P460 in inhibiting the proliferation of cancer cells and increasing the number of tumor cells undergoing apoptosis. Cell adhesion analysis and tumor imaging results revealed that P462 showed more specific and extensive binding with tumor cells and greater accumulation in tumors than the wild-type peptide. Importantly, treatment with P462 was more efficacious than that with P460 in vivo and was associated with considerably improved tumor-homing activity. This study highlights the importance of the roles of the tumor-homing sequence RGDR in the enhancement in cell attachment and tumor accumulation. The results of this work indicate that P462 could be a novel drug candidate for tumor treatment.

Current and Emerging Diagnostic, Prognostic, and Predictive Biomarkers in Head and Neck Cancer

Head and neck cancers (HNC) are a biologically diverse set of cancers that are responsible for over 660,000 new diagnoses each year. Current therapies for HNC require a comprehensive, multimodal approach encompassing resection, radiation therapy, and systemic therapy. With an increased understanding of the mechanisms behind HNC, there has been growing interest in more accurate prognostic indicators of disease, effective post-treatment surveillance, and individualized treatments. This chapter will highlight the commonly used and studied biomarkers in head and neck squamous cell carcinoma.

Exploring Potentilla nepalensis Phytoconstituents: Integrated Strategies of Network Pharmacology, Molecular Docking, Dynamic Simulations, and MMGBSA Analysis for Cancer Therapeutic Targets Discovery

Potentilla nepalensis belongs to the Rosaceae family and has numerous therapeutic applications as potent plant-based medicine. Forty phytoconstituents (PCs) from the root and stem through n-hexane (NR and NS) and methanolic (MR and MS) extracts were identified in earlier studies. However, the PCs affecting human genes and their roles in the body have not previously been disclosed. In this study, we employed network pharmacology, molecular docking, molecular dynamics simulations (MDSs), and MMGBSA methodologies. The SMILES format of PCs from the PubChem was used as input to DIGEP-Pred, with 764 identified as the inducing genes. Their enrichment studies have shown inducing genes' gene ontology descriptions, involved pathways, associated diseases, and drugs. PPI networks constructed in String DB and network topological analyzing parameters performed in Cytoscape v3.10 revealed three therapeutic targets: TP53 from MS-, NR-, and NS-induced genes; HSPCB and Nf-kB1 from MR-induced genes. From 40 PCs, two PCs, 1b (MR) and 2a (MS), showed better binding scores (kcal/mol) with p53 protein of -8.6 and -8.0, and three PCs, 3a, (NR) 4a, and 4c (NS), with HSP protein of -9.6, -8.7, and -8.2. MDS and MMGBSA revealed these complexes are stable without higher deviations with better free energy values. Therapeutic targets identified in this study have a prominent role in numerous cancers. Thus, further investigations such as in vivo and in vitro studies should be carried out to find the molecular functions and interlaying mechanism of the identified therapeutic targets on numerous cancer cell lines in considering the PCs of P. nepalensis.

The nuclear factor erythroid 2-related factor 2/p53 axis in breast cancer

One of the most important factors involved in the response to oxidative stress (OS) is the nuclear factor erythroid 2-related factor 2 (Nrf2), which regulates the expression of components such as antioxidative stress proteins and enzymes. Under normal conditions, Kelch-like ECH-associated protein 1 (Keap1) keeps Nrf2 in the cytoplasm, thus preventing its translocation to the nucleus and inhibiting its role. It has been established that Nrf2 has a dual function; on the one hand, it promotes angiogenesis and cancer cell metastasis while causing resistance to drugs and chemotherapy. On the other hand, Nrf2 increases expression and proliferation of glutathione to protect cells against OS. p53 is a tumour suppressor that activates the apoptosis pathway in aging and cancer cells in addition to stimulating the glutaminolysis and antioxidant pathways. Cancer cells use the antioxidant ability of p53 against OS. Therefore, in the present study, we discussed function of Nrf2 and p53 in breast cancer (BC) cells to elucidate their role in protection or destruction of cancer cells as well as their drug resistance or antioxidant properties.

The Development of p53-Targeted Therapies for Human Cancers

p53 plays a critical role in tumor suppression and is the most frequently mutated gene in human cancers. Most p53 mutants (mutp53) are missense mutations and are thus expressed in human cancers. In human cancers that retain wtp53, the wtp53 activities are downregulated through multiple mechanisms. For example, the overexpression of the negative regulators of p53, MDM2/MDMX, can also efficiently destabilize and inactivate wtp53. Therefore, both wtp53 and mutp53 have become promising and intensively explored therapeutic targets for cancer treatment. Current efforts include the development of small molecule compounds to disrupt the interaction between wtp53 and MDM2/MDMX in human cancers expressing wtp53 and to restore wtp53-like activity to p53 mutants in human cancers expressing mutp53. In addition, a synthetic lethality approach has been applied to identify signaling pathways affected by p53 dysfunction, which, when targeted, can lead to cell death. While an intensive search for p53-targeted cancer therapy has produced potential candidates with encouraging preclinical efficacy data, it remains challenging to develop such drugs with good efficacy and safety profiles. A more in-depth understanding of the mechanisms of action of these p53-targeting drugs will help to overcome these challenges.

The Role of Genetic Mutations in Mitochondrial-Driven Cancer Growth in Selected Tumors: Breast and Gynecological Malignancies

There is an increasing understanding of the molecular and cytogenetic background of various tumors that helps us better conceptualize the pathogenesis of specific diseases. Additionally, in many cases, these molecular and cytogenetic alterations have diagnostic, prognostic, and/or therapeutic applications that are heavily used in clinical practice. Given that there is always room for improvement in cancer treatments and in cancer patient management, it is important to discover new therapeutic targets for affected individuals. In this review, we discuss mitochondrial changes in breast and gynecological (endometrial and ovarian) cancers. In addition, we review how the frequently altered genes in these diseases (BRCA1/2, HER2, PTEN, PIK3CA, CTNNB1, RAS, CTNNB1, FGFR, TP53, ARID1A, and TERT) affect the mitochondria, highlighting the possible associated individual therapeutic targets. With this approach, drugs targeting mitochondrial glucose or fatty acid metabolism, reactive oxygen species production, mitochondrial biogenesis, mtDNA transcription, mitophagy, or cell death pathways could provide further tailored treatment.

TP53 Alterations in Myelodysplastic Syndromes and Acute Myeloid Leukemia

TP53 mutations are less frequent in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) than in solid tumors, except in secondary and therapy-related MDS/AMLs, and in cases with complex monosomal karyotype. As in solid tumors, missense mutations predominate, with the same hotspot mutated codons (particularly codons 175, 248, 273). As TP53-mutated MDS/AMLs are generally associated with complex chromosomal abnormalities, it is not always clear when TP53 mutations occur in the pathophysiological process. It is also uncertain in these MDS/AML cases, which often have inactivation of both TP53 alleles, if the missense mutation is only deleterious through the absence of a functional p53 protein, or through a potential dominant-negative effect, or finally a gain-of-function effect of mutant p53, as demonstrated in some solid tumors. Understanding when TP53 mutations occur in the disease course and how they are deleterious would help to design new treatments for those patients who generally show poor response to all therapeutic approaches.

Mechanisms of myeloid leukemogenesis: Current perspectives and therapeutic objectives

Acute myeloid leukemia (AML) is a heterogeneous hematopoietic neoplasm which results in clonal proliferation of abnormally differentiated hematopoietic cells. In this review, mechanisms contributing to myeloid leukemogenesis are summarized, highlighting aberrations of epigenetics, transcription factors, signal transduction, cell cycling, and the bone marrow microenvironment. The mechanisms contributing to AML are detailed to spotlight recent findings that convey clinical impact. The applications of current and prospective therapeutic targets are accentuated in addition to reviews of treatment paradigms stratified for each characteristic molecular lesion - with a focus on exploring novel treatment approaches and combinations to improve outcomes in AML.

Role of p53 in breast cancer progression: An insight into p53 targeted therapy

The transcription factor p53 is an important regulator of a multitude of cellular processes. In the presence of genotoxic stress, p53 is activated to facilitate DNA repair, cell cycle arrest, and apoptosis. In breast cancer, the tumor suppressive activities of p53 are frequently inactivated by either the overexpression of its negative regulator MDM2, or mutation which is present in 30-35% of all breast cancer cases. Notably, the frequency of p53 mutation is highly subtype dependent in breast cancers, with majority of hormone receptor-positive or luminal subtypes retaining the wild-type p53 status while hormone receptor-negative patients predominantly carry p53 mutations with gain-of-function oncogenic activities that contribute to poorer prognosis. Thus, a two-pronged strategy of targeting wild-type and mutant p53 in different subtypes of breast cancer can have clinical relevance. The development of p53-based therapies has rapidly progressed in recent years, and include unique small molecule chemical inhibitors, stapled peptides, PROTACs, as well as several genetic-based approaches using vectors and engineered antibodies. In this review, we highlight the therapeutic strategies that are in pre-clinical and clinical development to overcome p53 inactivation in both wild-type and mutant p53-bearing breast tumors, and discuss their efficacies and limitations in pre-clinical and clinical settings.

Identification of potential target genes of breast cancer in response to Chidamide treatment

Chidamide, a new chemically structured HDACi-like drug, has been shown to inhibit breast cancer, but its specific mechanism has not been fully elucidated. In this paper, we selected ER-positive breast cancer MCF-7 cells and used RNA-seq technique to analyze the gene expression differences of Chidamide-treated breast cancer cells to identify the drug targets of Chidamide's anti-breast cancer effect and to lay the foundation for the development of new drugs for breast cancer treatment. The results showed that the MCF-7 CHID group expressed 320 up-regulated genes and 222 down-regulated genes compared to the control group; Gene Ontology functional enrichment analysis showed that most genes were enriched to biological processes. Subsequently, 10 hub genes for Chidamide treatment of breast cancer were identified based on high scores using CytoHubba, a plug-in for Cytoscape: TP53, JUN, CAD, ACLY, IL-6, peroxisome proliferator-activated receptor gamma, THBS1, CXCL8, IMPDH2, and YARS. Finally, a combination of the Gene Expression Profiling Interactive Analysis database and Kaplan Meier mapper to compare the expression and survival analysis of these 10 hub genes, TP53, ACLY, PPARG, and JUN were found to be potential candidate genes significantly associated with Chidamide for breast cancer treatment. Among them, TP53 may be a potential target gene for Chidamide to overcome multi-drug resistance in breast cancer. Therefore, we identified four genes central to the treatment of breast cancer with Chidamide by bioinformatics analysis, and clarified that TP53 may be a potential target gene for Chidamide to overcome multi-drug resistance in breast cancer. This study lays a solid experimental and theoretical foundation for the treatment of breast cancer at the molecular level with Chidamide and for the combination of Chidamide.

Transcription profiling of feline mammary carcinomas and derived cell lines reveals biomarkers and drug targets associated with metabolic and cell cycle pathways

The molecular heterogeneity of feline mammary carcinomas (FMCs) represents a prognostic and therapeutic challenge. RNA-Seq-based comparative transcriptomic profiling serves to identify recurrent and exclusive differentially expressed genes (DEGs) across sample types and molecular subtypes. Using mass-parallel RNA-Seq, we identified DEGs and performed comparative function-based analysis across 15 tumours (four basal-like triple-negative [TN], eight normal-like TN, and three luminal B fHER2 negative [LB fHER2-]), two cell lines (CL, TiHo-0906, and TiHo-1403) isolated from the primary tumours (LB fHER2-) of two cats included in this study, and 13 healthy mammary tissue controls. DEGs in tumours were predominantly upregulated; dysregulation of CLs transcriptome was more extensive, including mostly downregulated genes. Cell-cycle and metabolic-related DEGs were upregulated in both tumours and CLs, including therapeutically-targetable cell cycle regulators (e.g. CCNB1, CCNB2, CDK1, CDK4, GTSE1, MCM4, and MCM5), metabolic-related genes (e.g. FADS2 and SLC16A3), heat-shock proteins (e.g. HSPH1, HSP90B1, and HSPA5), genes controlling centrosome disjunction (e.g. RACGAP1 and NEK2), and collagen molecules (e.g. COL2A1). DEGs specifically upregulated in basal-like TN tumours were involved in antigen processing and presentation, in normal-like TN tumours encoded G protein-coupled receptors (GPCRs), and in LB fHER2- tumours were associated with lysosomes, phagosomes, and endosomes formation. Downregulated DEGs in CLs were associated with structural and signalling cell surface components. Hence, our results suggest that upregulation of genes enhancing proliferation and metabolism is a common feature among FMCs and derived CLs. In contrast, the dissimilarities observed in dysregulation of membrane components highlight CLs' disconnection with the tumour microenvironment. Furthermore, recurrent and exclusive DEGs associated with dysregulated pathways might be useful for the development of prognostically and therapeutically-relevant targeted panels.

Human RAD51 Protein Forms Amyloid-like Aggregates In Vitro

RAD51 is a central protein of homologous recombination and DNA repair processes that maintains genome stability and ensures the accurate repair of double-stranded breaks (DSBs). In this work, we assessed amyloid properties of RAD51 in vitro and in the bacterial curli-dependent amyloid generator (C-DAG) system. Resistance to ionic detergents, staining with amyloid-specific dyes, polarized microscopy, transmission electron microscopy (TEM), X-ray diffraction and other methods were used to evaluate the properties and structure of RAD51 aggregates. The purified human RAD51 protein formed detergent-resistant aggregates in vitro that had an unbranched cross-β fibrillar structure, which is typical for amyloids, and were stained with amyloid-specific dyes. Congo-red-stained RAD51 aggregates demonstrated birefringence under polarized light. RAD51 fibrils produced sharp circular X-ray reflections at 4.7 Å and 10 Å, demonstrating that they had a cross-β structure. Cytoplasmic aggregates of RAD51 were observed in cell cultures overexpressing RAD51. We demonstrated that a key protein that maintains genome stability, RAD51, has amyloid properties in vitro and in the C-DAG system and discussed the possible biological relevance of this observation.

Clinical Profile and Survival Outcome of Endometrial Cancer with p53 Mutation

Clinicopathologic classification of endometrial cancer imperfectly reflects the tumor biology. Pathologic categorization - especially in high-grade tumors - results in an imprecise estimation of the risk of disease, recurrence, and death. Molecular subtyping is emerging as the standard of care in diagnosis and treatment of endometrial cancers. Molecular markers are important prognostic factors in tumor dissemination and early recurrence of endometrial cancers. TP53 mutation is an important prognostic factor for both serous and endometrioid cancers. The study aims to compare the clinical profile and overall survival of endometrial cancers with and without p53 mutation. Sixty-three patients who underwent surgical staging for carcinoma endometrium were included in the study.TP53 mutation status was determined based on p53 expression by immunohistochemistry (IHC) as a p53 wild or p53 mutant type. Data were analyzed for the clinical profile, p53 mutation status on IHC, histological pattern, tumor grade, stage of the disease, lymph node spread, recurrence pattern, treatment received, 2-year disease-free survival, and overall survival. Recurrence was noted in 12.7% patients after 2-year follow-up, of which 75% patients had p53 mutation. Significant association was seen between p53 expression and high-grade tumors, stage, cervical involvement, and adnexal involvement. The 2-year overall survival of the p53 wild type was 97.2% and the p53 mutant type was 91.7%. The 2-year disease-free survival for the p53 wild type was 94.3% and the disease-free survival of the p53 mutant variety was 83.5%. The 2-year disease-free survival for endometrioid carcinoma with p53 wild type was 100% and p53 mutant variety was 86.2% (p value 0.033). About 15.9% (10) patients were reassigned to the high-risk group needing chemotherapy and radiation according to the ESGO ESTRO 2021 consensus classification, due to their p53 mutation status. IHC to assess somatic p53 mutation may be done in endometrial biopsies irrespective of their histology. This may help to identify that the aggressive tumors thereby help in tailoring surgery, planning adjuvant treatment, and follow-up.

Targeting TP53-Mutated Acute Myeloid Leukemia: Research and Clinical Developments

TP53 is a key tumor suppressor gene that plays an important role in regulating apoptosis, senescence, and DNA damage repair in response to cellular stress. Although somewhat rare, TP53-mutated AML has been identified as an important molecular subgroup with a prognosis that is arguably the worst of any. Survival beyond one year is rare after induction chemotherapy with or without consolidative allogeneic stem cell transplant. Although response rates have been improved with hypomethylating agents, outcomes remain particularly poor due to short response duration. Improvements in our understanding of AML genetics and biology have led to a surge in novel treatment options, though the clinical applicability of these agents in TP53-mutated disease remains largely unknown. This review will focus on the epidemiology, molecular characteristics, and clinical significance of TP53 mutations in AML as well as emerging treatment options that are currently being studied.

Activating transcription factor 3 mediates apoptotic functions through a p53-independent pathway in human papillomavirus 18 infected HeLa cells

Activating transcription factor 3 (ATF3) is the first p53 stability regulator that interferes with the ubiquitination of p53. However, the E6 oncoprotein of high-risk human papillomaviruses (HPVs) binds to and induces proteasome-dependent degradation of the host p53 protein. Herein, we investigate the effects of ATF3 overexpression on cell cycle progression and apoptosis in HPV-18-infected HeLa cells, and further examine whether ATF3 could alter the apoptosis level of HeLa cells through the inhibition of E6-mediated p53 degradation. Cytological function of HeLa cells prior and subsequent to the overexpression of ATF3 was assessed using cell cycle and annexin V/PI flow cytometry analysis. Western blotting assays revealed no significant effect of ATF3 on the levels of p53 and E6 in HeLa cells. However, annexin V staining demonstrated increases in apoptosis. ATF3 acts as a tumor suppressor factor in HPV18-related cervical cancer which mediates apoptotic functions through a p53-independent pathway.

[Research Advances of EGFR-TP53 Co-mutation in Advanced Non-small Cell Lung Cancer]

With the rapid development and wide application of next generation sequencing (NGS) technology, a series of researches have revealed that concurrent genetic alterations play an important role in the response and resistance of epidermal growth factor receptor (EGFR)-mutant NSCLC to EGFR-tyrosine kinase inhibitor (TKI). Besides, TP53 mutation is the most common co-mutation gene in EGFR-mutant NSCLC, which has been proved to confer a worse prognosis in EGFR-mutated patients treated with first, second and third generation of EGFR-TKIs. Currently, it is still being explored how to select the best treatment strategies for patients with concomitant presence of TP53 mutation in EGFR-mutant NSCLC. Here, we review the literature on recent research progress of TP53 concurrent mutation in EGFR-mutant advanced NSCLC.
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Allicin induces cell cycle arrest and apoptosis of breast cancer cells in vitro via modulating the p53 pathway

BACKGROUND

The tumor suppressor protein p53 is a most promising target for the development of anticancer drugs. Allicin (diallylthiosulfinate) is one of the most active components of garlic (Alliium sativum L.) and possesses a variety of health-promoting properties with pharmacological applications. However, whether allicin plays an anti-cancer role against breast cancer cells through the induction of p53-mediated apoptosis remains unknown.

METHODS AND RESULTS

In this study, we investigate the anti-breast cancer effect of allicin in vitro by using MCF-7 and MD-MBA-231 cells. We found that allicin reduces cell viability, induces apoptosis and cell cycle arrest in both cells. Allicin activated p53 and caspase 3 expressions in both cells but produced different effects on the expression of p53-related biomarkers. In MDA-MB-231 cells, allicin up-regulated the mRNA and protein expression of A1BG and THBS1 while down-regulated the expression of TPM4. Conversely, the mRNA and protein expression of A1BG, THBS1 and TPM4 were all reduced in MCF-7 cells. Hence, allicin induces cell cycle arrest and apoptosis in breast cancer cells through p53 activation but it effects on the expression of p53-related biomarkers were dependent upon the specific type of breast cancer involved.

CONCLUSIONS

These findings suggest that allicin induces apoptosis and regulates biomarker expression in breast cancer cell lines through modulating the p53 signaling pathway. Furthermore, our results promote the utility of allicin as compound for further studies as an anticancer drug targeting p53.

Development and Validation of a Gene Mutation-Associated Nomogram for Hepatocellular Carcinoma Patients From Four Countries

Background: Genomic alteration is the basis of occurrence and development of carcinoma. Specific gene mutation may be associated with the prognosis of hepatocellular carcinoma (HCC) patients without distant or lymphatic metastases. Hence, we developed a nomogram based on prognostic gene mutations that could predict the overall survival of HCC patients at early stage and provide reference for immunotherapy.

Methods: HCC cohorts were obtained from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) databases. The total patient was randomly assigned to training and validation sets. Univariate and multivariate cox analysis were used to select significant variables for construction of nomogram. The support vector machine (SVM) and principal component analysis (PCA) were used to assess the distinguished effect of significant genes. Besides, the nomogram model was evaluated by concordance index, time-dependent receiver operating characteristics (ROC) curve, calibration curve and decision curve analysis (DCA). Gene Set Enrichment Analysis (GSEA), CIBERSORT, Tumor Immune Dysfunction and Exclusion (TIDE) and Immunophenoscore (IPS) were utilized to explore the potential mechanism of immune-related process and immunotherapy.

Results: A total of 695 HCC patients were selected in the process including 495 training patients and 200 validation patients. Nomogram was constructed based on T stage, age, country, mutation status of DOCK2, EYS, MACF1 and TP53. The assessment showed the nomogram has good discrimination and high consistence between predicted and actual data. Furthermore, we found T cell exclusion was the potential mechanism of malignant progression in high-risk group. Meanwhile, low-risk group might be sensitive to immunotherapy and benefit from CTLA-4 blocker treatment.

Conclusion: Our research established a nomogram based on mutant genes and clinical parameters, and revealed the underlying association between these risk factors and immune-related process.

Synthesis and biological evaluation of a novel anticancer agent CBISC that induces DNA damage response and diminishes levels of mutant-p53

A novel nitrogen mustard CBISC has been synthesized and evaluated as an anticancer agent. CBISC has been shown to exhibit enhanced cell proliferation inhibition properties against mutant p53 cell lines colorectal cancer WiDr, pancreatic cancer (MIAPaCa-2 and PANC-1), and triple negative breast cancer (MDA-MB-231 and MDA-MB-468). In vitro mechanism of action studies revealed perturbations in the p53 pathway and increased cell death as evidenced by western blotting, immunofluorescent microscopy and MTT assay. Further, in vivo studies revealed that CBISC is well tolerated in healthy mice and exhibited significant in vivo tumor growth inhibition properties in WiDr and MIAPaCa-2 xenograft models. These studies illustrate the potential utility of CBISC as an anticancer agent.

Synergistic Therapy for Cervical Cancer by Codelivery of Cisplatin and JQ1 Inhibiting Plk1-Mutant Trp53 Axis

JQ1, a specific inhibitor of bromodomain-containing protein 4 (BRD4), could have great potential in the treatment of cervical cancer. However, its clinical application is limited by its short plasma half-life and limited antitumor efficacy. In this work, cisplatin (CDDP) was first utilized as the stabilizer and cooperator in the nanosystem (mPEG₁₁₃-b-P(Glu₁₀-co-Phe₁₀)-CDDP/JQ1, called PGP-CDDP/JQ1) to break through the efficiency limitation of JQ1. The PGP-CDDP/JQ1 had a combination index (CI) of 0.21, exerting a strong cytotoxic synergistic effect. In vivo experiments revealed that PGP-CDDP/JQ1 had a significantly higher tumor inhibition effect (tumor inhibition rate: 85% vs 14%) and plasma stability of JQ1 (area under the curve (AUC_0-∞): 335.97 vs 16.88 μg × h/mL) than free JQ1. The mechanism underling the synergism of JQ1 with CDDP in PGP-CDDP/JQ1 was uncovered to be inhibiting Plk1-mutant Trp53 axis. Thus, this study provides an optional method for improving the clinical application of JQ1 in cervical cancer.

High-resolution melting effectively pre-screens for TP53 mutations before direct sequencing in patients with diffuse glioma

TP53 mutations are important molecular markers in diffuse astrocytic tumors and medulloblastomas. We examined the efficacy of a pre-screening method for high-resolution melting (HRM) analysis of TP53 mutation before direct sequencing using samples from patients with diffuse glioma. Surgical samples from 64 diffuse gliomas were classified based on the 2016 World Health Organization (WHO) histopathological grading system and the cIMPACT-NOW (consortium to inform molecular and practical approaches to CNS tumor taxonomy-not official WHO) update. TP53 mutations from exon 5 to exon 8 were assessed by direct sequencing. The results of HRM and p53 immunohistochemistry (IHC) analysis were compared by recording the sensitivity, specificity, and false negative and false positive rates. Direct sequencing detected TP53 mutations in 18 of 64 samples (28.1%): diffuse astrocytoma, IDH-mutant (n = 3); diffuse astrocytoma, IDH-wild type (n = 1); anaplastic astrocytoma, IDH-mutant (n = 3); anaplastic astrocytoma, IDH-wild type (n = 4); and glioblastoma, IDH-wild type (n = 7). A total of 22 mutations was detected in the 18 samples; 4 samples exhibited duplicate missense mutations. Sensitivity and specificity were 0.96 and 0.96, respectively, for HRM analysis; they were 0.89 and 0.52, respectively, for p53 IHC. Overall accuracy was 0.98 for HRM and 0.63 for IHC. HRM analysis is a good pre-screening method for the detection of TP53 mutation before direct sequencing.

SILAC-Based Quantitative Proteomic Analysis of Oxaliplatin-Resistant Pancreatic Cancer Cells

Simple Summary

Resistance to oxaliplatin remains a major challenge in pancreatic cancer therapy. However, molecular mechanisms underlying oxaliplatin resistance in pancreatic cancer is still unclear. The aim of this study was to identify global changes of proteins involved in oxaliplatin resistance in pancreatic cancer cells, thereby elucidating the multiple mechanisms of oxaliplatin resistance in pancreatic cancer. We presented the quantitative proteomic profiling of oxaliplatin-resistant pancreatic cancer cells via a stable isotope labelling by amino acids in cell culture (SILAC)-based shotgun proteomic approach. Multiple biological processes including DNA repair, cell cycle process, and type I interferon signaling pathway were enriched in oxaliplatin-resistant pancreatic cancer cells. Furthermore, we demonstrated that both Wntless homolog protein (WLS) and myristoylated alanine-rich C-kinase substrate (MARCKS) could participate in oxaliplatin resistance in pancreatic cancer cells.

Abstract

Oxaliplatin is a commonly used chemotherapeutic drug for the treatment of pancreatic cancer. Understanding the cellular mechanisms of oxaliplatin resistance is important for developing new strategies to overcome drug resistance in pancreatic cancer. In this study, we performed a stable isotope labelling by amino acids in cell culture (SILAC)-based quantitative proteomics analysis of oxaliplatin-resistant and sensitive pancreatic cancer PANC-1 cells. We identified 107 proteins whose expression levels changed (thresholds of 2-fold changes and p-value ≤ 0.05) between oxaliplatin-resistant and sensitive cells, which were involved in multiple biological processes, including DNA repair, cell cycle process, and type I interferon signaling pathway. Notably, myristoylated alanine-rich C-kinase substrate (MARCKS) and Wntless homolog protein (WLS) were upregulated in oxaliplatin-resistant cells compared to sensitive cells, as confirmed by qRT-PCR and Western blot analysis. We further demonstrated the activation of AKT and β-catenin signaling (downstream targets of MARCKS and WLS, respectively) in oxaliplatin-resistant PANC-1 cells. Additionally, we show that the siRNA-mediated suppression of both MARCKS and WLS enhanced oxaliplatin sensitivity in oxaliplatin-resistant PANC-1 cells. Taken together, our results provide insights into multiple mechanisms of oxaliplatin resistance in pancreatic cancer cells and reveal that MARCKS and WLS might be involved in the oxaliplatin resistance.

TP53 Mutations in Acute Myeloid Leukemia: Still a Daunting Challenge?

TP53 is a key tumor suppressor gene with protean functions associated with preservation of genomic balance, including regulation of cellular senescence, apoptotic pathways, metabolism functions, and DNA repair. The vast majority of de novo acute myeloid leukemia (AML) present unaltered TP53 alleles. However, TP53 mutations are frequently detected in AML related to an increased genomic instability, such as therapy‐related (t-AML) or AML with myelodysplasia-related changes. Of note, TP53 mutations are associated with complex cytogenetic abnormalities, advanced age, chemoresistance, and poor outcomes. Recent breakthroughs in AML research and the development of targeted drugs directed at specific mutations have led to an explosion of novel treatments with different mechanisms. However, optimal treatment strategy for patients harboring TP53 mutations remains a critical area of unmet need. In this review, we focus on the incidence and clinical significance of TP53 mutations in de novo and t-AML. The influence of these alterations on response and clinical outcomes as well as the current and future therapeutic perspectives for this hardly treatable setting are discussed.

Mutant p53 as a Regulator and Target of Autophagy

One of the most notoriously altered genes in human cancer is the tumor-suppressor TP53, which is mutated with high frequency in more cancers than any other tumor suppressor gene. Beyond the loss of wild-type p53 functions, mutations in the TP53 gene often lead to the expression of full-length proteins with new malignant properties. Among the defined oncogenic functions of mutant p53 is its effect on cell metabolism and autophagy. Due to the importance of autophagy as a stress adaptive response, it is frequently dysfunctional in human cancers. However, the role of p53 is enigmatic in autophagy regulation. While the complex action of the wild-type p53 on autophagy has extensively been described in literature, in this review, we focus on the conceivable role of distinct mutant p53 proteins in regulating different autophagic pathways and further discuss the available evidence suggesting a possible autophagy stimulatory role of mutant p53. Moreover, we describe the involvement of different autophagic pathways in targeting and degrading mutant p53 proteins, exploring the potential strategies of targeting mutant p53 in cancer by autophagy.

Tumor-specific lytic path “hyperploid progression mediated death”: Resolving side effects through targeting retinoblastoma or p53 mutant

A major advance was made to reduce the side effects of cancer therapy via the elucidation of the tumor-specific lytic path “hyperploid progression-mediated death” targeting retinoblastoma (Rb) or p53-mutants defective in G1 DNA damage checkpoint. The genetic basis of human cancers was uncovered through the cloning of the tumor suppressor Rb gene. It encodes a nuclear DNA-binding protein whose self-interaction is regulated by cyclin-dependent kinases. A 3D-structure of Rb dimer is shown, confirming its multimeric status. Rb assumes a central role in cell cycle regulation and the “Rb pathway” is universally inactivated in human cancers. Hyperploidy refers to a state in which cells contain one or more extra chromosomes. Hyperploid progression occurs due to continued cell-cycling without cytokinesis in G1 checkpoint-defective cancer cells. The evidence for the triggering of hyperploid progression-mediated death in RB-mutant human retinoblastoma cells is shown. Hence, the very genetic mutation that predisposes to cancer can be exploited to induce lethality. The discovery helped to establish the principle of targeted cytotoxic cancer therapy at the mechanistic level. By triggering the lytic path, targeted therapy with tumor specificity at the genetic level can be developed. It sets the stage for systematically eliminating side effects for cytotoxic cancer therapy.

Small molecule CDS-3078 induces G2/M phase arrest and mitochondria-mediated apoptosis in HeLa cells

The tumor suppressor p53 serves important roles in cell cycle arrest and apoptosis, and its activation increases the sensitivity of cancer cells to radiotherapy or chemotherapy. In the present study, the small molecule 2-[1-(4-(benzyloxy)phenyl)-3-oxoisoindolin-2-yl)-2-(4-methoxyphenyl)] acetic acid (CDS-3078) significantly increased p53 mRNA expression levels in a dose-dependent manner. Treatment with CDS-3078 increased p53 expression levels and p53-mediated activation of its downstream target genes in HeLa cells. Additionally, p53^+/+ HeLa cells treated with CDS-3078 presented with dysfunctional mitochondria, as indicated by the decrease in Bcl-2 levels, the increase in Bcl-2 homologous antagonist killer and the increase in cytochrome c release from the mitochondria to the cytoplasm. The present results suggested that CDS-3078 treatment significantly induced G₂/M phase cell cycle arrest. Therefore, CDS-3078 administration induced apoptosis via p53-mediated cell cycle arrest, causing mitochondrial dysfunction and resulting in apoptotic cell death in cervical cancer cells. Collectively, the present results suggested that CDS-3078 may be a potential anticancer agent.

Exploring the multiple roles of guardian of the genome: P53

Background

Cells have evolved balanced mechanisms to protect themselves by initiating a specific response to a variety of stress. TheTP53gene, encoding P53 protein, is one of the many widely studied genes in human cells owing to its multifaceted functions and complex dynamics. The tumour-suppressing activity of P53 plays a principal role in the cellular response to stress. The majority of the human cancer cells exhibit the inactivation of the P53 pathway. In this review, we discuss the recent advancements in P53 research with particular focus on the role of P53 in DNA damage responses, apoptosis, autophagy, and cellular metabolism. We also discussed important P53-reactivation strategies that can play a crucial role in cancer therapy and the role of P53 in various diseases.

Main body

We used electronic databases like PubMed and Google Scholar for literature search. In response to a variety of cellular stress such as genotoxic stress, ischemic stress, oncogenic expression, P53 acts as a sensor, and suppresses tumour development by promoting cell death or permanent inhibition of cell proliferation. It controls several genes that play a role in the arrest of the cell cycle, cellular senescence, DNA repair system, and apoptosis. P53 plays a crucial role in supporting DNA repair by arresting the cell cycle to purchase time for the repair system to restore genome stability. Apoptosis is essential for maintaining tissue homeostasis and tumour suppression. P53 can induce apoptosis in a genetically unstable cell by interacting with many pro-apoptotic and anti-apoptotic factors.

Furthermore, P53 can activate autophagy, which also plays a role in tumour suppression. P53 also regulates many metabolic pathways of glucose, lipid, and amino acid metabolism. Thus under mild metabolic stress, P53 contributes to the cell’s ability to adapt to and survive the stress.

Conclusion

These multiple levels of regulation enable P53 to perform diversified roles in many cell responses. Understanding the complete function of P53 is still a work in progress because of the inherent complexity involved in between P53 and its target proteins. Further research is required to unravel the mystery of this Guardian of the genome “TP53”.

The head and neck cancer genome in the era of immunotherapy

The recent success of immunotherapy in head and neck squamous cell carcinoma (HNSCC) has necessitated a new perspective on the cancer genome. Here we review recent advances in the carcinogenesis and molecular genetics of HNSCC with an eye on their implications for cancer immunity. Newer sequencing technologies have recently facilitated dissection of the complex interaction between the HPV virus, tumor, host factors, and the tumor microenvironment (TME) that help shed light on how the immune system interacts with head and neck malignancies.

Targeting PARP and autophagy evoked synergistic lethality in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), one of the most lethal malignancies worldwide, has limited efficient therapeutic options. Here, we first demonstrated that simultaneously targeting poly (ADP-ribose) polymerase (PARP) and autophagy could evoke striking synergistic lethality in HCC cells. Specifically, we found that the PARP inhibitor Niraparib induced cytotoxicity accompanied by significant autophagy formation and autophagic flux in HCC cells. Further experiments showed that Niraparib induced suppression of the Akt/mTOR pathway and activation of the Erk1/2 cascade, two typical signaling pathways related to autophagy. In addition, the accumulation of reactive oxygen species was triggered, which was involved in Niraparib-induced autophagy. Blocking autophagy by chloroquine (CQ) in combination with Niraparib further enhanced cytotoxicity, induced apoptosis and inhibited colony formation in HCC cells. Synergistic inhibition was also observed in Huh7 xenografts in vivo. Mechanistically, we showed that autophagy inhibition abrogated Niraparib-induced cell-cycle arrest and checkpoint activation. Cotreatment with CQ and Niraparib promoted the formation of γ-H2AX foci while inhibiting the recruitment of the homologous recombination repair protein RAD51 to double-strand break sites. Thus, the present study developed a novel promising strategy for the management of HCC in the clinic and highlighted a potential approach to expand the application of PARP inhibitors.

2-(6-Hydroxyhexylthio)-5,8-dimethoxy-1,4-naphthoquinone Induces Apoptosis through ROS-Mediated MAPK, STAT3, and NF-κB Signalling Pathways in Lung Cancer A549 Cells

Two novel compounds, 2-(2-hydroxyethylthio)-5,8-dimethoxy-1,4-naphthoquinone (HEDMNQ) and 2-(6-hydroxyhexylthio)-5,8-dimethoxy-1,4-naphthoquinone (HHDMNQ), were synthesized to investigate the kill effects and mechanism of 1,4-naphthoquinone derivatives in lung cancer cells. The results of the CCK-8 assay showed that HEDMNQ and HHDMNQ had significant cytotoxic effects on A549, NCI-H23, and NCI-H460 NSCLC cells. Flow cytometry and western blot results indicated that HHDMNQ induced A549 cell cycle arrest at the G2/M phase by decreasing the expression levels of cyclin-dependent kinase 1/2 and cyclin B1. Fluorescence microscopy and flow cytometry results indicated that HHDMNQ could induce A549 cell apoptosis, and western blot analysis showed that HHDMNQ induced apoptosis through regulating the mitochondria pathway, as well as the MAPK, STAT3, and NF-κB signalling pathways. Flow cytometry results showed that intracellular reactive oxygen species (ROS) levels were increased after HHDMNQ treatment, and western blot showed that ROS could modulate the intrinsic pathway and MAPK, STAT3, and NF-κB signalling pathways. These effects were blocked by the ROS inhibitor N-acetyl-L-cysteine in A549 cells. Our findings suggest that compared with HEDMNQ, HHDMNQ had the stronger ability to inhibit the cell viability of lung cancer cells and induce apoptosis by regulating the ROS-mediated intrinsic pathway and MAPK/STAT3/NF-κB signalling pathways. Thus, HHDMNQ might be a potential antitumour compound for treating lung cancer.

Follow the Mutations: Toward Class-Specific, Small-Molecule Reactivation of p53

The mutational landscape of p53 in cancer is unusual among tumor suppressors because most of the alterations are of the missense type and localize to a single domain: the ~220 amino acid DNA-binding domain. Nearly all of these mutations produce the common effect of reducing p53’s ability to interact with DNA and activate transcription. Despite this seemingly simple phenotype, no mutant p53-targeted drugs are available to treat cancer patients. One of the main reasons for this is that the mutations exert their effects via multiple mechanisms—loss of DNA contacts, reduction in zinc-binding affinity, and lowering of thermodynamic stability—each of which involves a distinct type of physical impairment. This review discusses how this knowledge is informing current efforts to develop small molecules that repair these defects and restore function to mutant p53. Categorizing the spectrum of p53 mutations into discrete classes based on their inactivation mechanisms is the initial step toward personalized cancer therapy based on p53 allele status.

Advances in Genomic Profiling and Risk Stratification in Acute Myeloid Leukemia

OBJECTIVE

To review the current state of molecular and genetic profiling of acute myeloid leukemia (AML) and its implications.

DATA SOURCE

Peer-reviewed journal articles.

CONCLUSION

Significant advances in the understanding of the pathology of acute myeloid leukemia have led to refined risk stratification of patients and application of novel targeted therapies based on genetic profiles. Minimal residual disease testing allows for highly sensitive disease surveillance that can be used to predict relapse and assess treatment response.

IMPLICATIONS FOR NURSING PRACTICE

Accurate prognostication and therapeutic decision-making for patients with acute myeloid leukemia is dependent on molecular profiling. Being knowledgeable of the implications of minimal residual disease testing is critical for patient-centered care.

TP53 Gain-of-Function Mutations in Circulating Tumor DNA in Men With Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

Circulating tumor DNA (ctDNA), which can be assessed by liquid biopsy, can provide valuable genomic information that may affect treatment response in prostate cancer. The aim of this study was to characterize TP53 mutations and treatment history in prostate cancer.

PATIENTS AND METHODS

This study included 143 patients with metastatic castration-resistant prostate cancer who had undergone ctDNA sequencing via Guardant360 testing. The presence or absence of TP53 mutations was analyzed along with treatment history for this group. TP53 mutations were further classified as gain of function (GOF) or not GOF, and analyzed with prior therapies.

RESULTS

Chi-square analysis was performed for treatment history and TP53 status (further specified as all TP53 mutations or only TP53 GOF mutations). There were no associations between prior receipt of abiraterone/enzalutamide therapy and all TP53 mutations, or between docetaxel therapy and all TP53 mutations. However, TP53 GOF mutations had a positive association with prior abiraterone/enzalutamide therapy (P = .047). There was no association of TP53 GOF mutations with prior docetaxel therapy. The most frequent alterations co-occurring with all TP53 mutations were in AR, BRAF, EGFR, MYC, and PIK3CA. Common coalterations with TP53 GOF mutations included AR, BRAF, EGFR, RB1, NF1, and PIK3CA. There was an association of RB1 mutations with TP53 GOF mutations, versus RB1 mutations and no TP53 GOF mutations (P = .0036).

CONCLUSION

TP53 GOF mutations may provide a valuable pathway to delineate metastatic castration-resistant prostate cancer TP53 mutations into therapeutic categories. Association with disease progression while receiving abiraterone/enzalutamide therapy was apparent in this study; however, further studies are needed to elaborate the therapeutic and prognostic implications.

P21 and P27 promote tumorigenesis and progression via cell cycle acceleration in seminal vesicles of TRAMP mice

Transgenic adenocarcinoma mouse prostate (TRAMP) model is established to mimic human prostate cancer progression, where seminal vesicle lesions often occur and has been described as phyllodes-like epithelial-stromal tumors. However, the molecular mechanism regulating tumorigenesis and progression in seminal vesicles of TRAMP mice remains largely unknown. In this study, C57BL/6 TRAMP mice were found to have a significantly shorter lifespan than wild-type (WT) mice and all of the seminal vesicles were markedly increased in size and weight with age from 24 weeks exhibiting a clearly papillary-phyllode pattern, though no obvious difference was observed in multiple organs including heart, liver, spleen, lungs, kidneys, testicles and bone between TRAMP and WT mice, and less than 10% of TRAMP mice developed prostate tumors. Western blotting showed Cyclin (CCN) B1 and CCND1 were remarkably overexpressed in seminal vesicle tumors of TRAMP mice at 24 weeks of age and increased with age till the end of trial, which was confirmed by Immunohistochemistry (IHC). P21 and P27 were also significantly augmented, whereas P53 and phosphorylated P53 (p-P53) were constantly expressed in normal controls and P53 did not appear to be mutated. Not only cyclin-dependent kinase (CDK) 1 and phosphorylated forkhead box protein (FOX) O1 but also CDK4, CDK6 and phosphorylated retinoblastoma-associated protein (RB) had similar increase trends, so did epidermal growth factor receptor (EGFR), AKT serine/threonine kinase (AKT), and their respective phosphorylation levels. Signal transducer and activator of transcription (STAT) 3, p-STAT3, enhancer of zeste homolog 2 (EZH2) and EZH2 mediated trimethylation of histone H3 lysine 27 (H3K27me3) were considerably elevated, too. Taken together, this finding suggests P21 and P27 promote carcinogenesis and development in seminal vesicles of TRAMP mice via accelerating cell cycle progression, in which oncogenic transformation of P21 and P27 might be through regulation of EGFR-AKT signaling.

The Effect of Bacterial Peptide p28 on Viability and Apoptosis Status of P53-null HeLa Cells

Purpose: Despite all the efforts for discovery of efficient anti-cancer therapeutics, cancer is still a major health concern worldwide. p28 is a bacterial small peptide which has been widely investigated due to its preferential cell internalization and anti-cancer activities. Intracellularly, p28 offers its anti-cancer traits by impeding the degradation of tumor-suppressor protein "p53". In this study, we investigated the potency of p28 in inducing apoptosis or decreasing cell viability in p53-null "HeLa" cell line. Methods: The coding sequence for p28 peptide was obtained from Pseudomonas aeruginosa by PCR amplification of the p28 gene. The coding gene was cloned in pET-28a vector and transformed into E. coli bacterial host. Subsequently, the expressed peptide was purified using Ni-NTA chromatography system and introduced into the target cells. The anti-proliferative and apoptotic activity of p28 on HeLa and HEK-293 cells were investigated using MTT and PEAnnexin V Flowcytometry assays. Results: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting confirmed the expression of p28 peptide in the bacterial host. Bradford assay revealed a concentration of 0.05 mg/mL for the purified p28. MTT assay of cells treated with p28 at concentrations of 0, 0.5, 1, 2 and 2.5 µM indicated 24h viability values of 97%, 89%, 88%, 87% and 84% for HeLa cells, respectively. Data obtained from flowcytometry analyses revealed 24h apoptosis rate of 7.17%, 8.05%, 8.63% and 8.84% for HeLa cells treated with 0, 0.5, 1, and 2 µM p28, respectively. Conclusion: MTT and flowcytometry apoptosis assays suggest no statistically significant effect of p28 on the viability and apoptosis status of p53-null HeLa cells when results compared to data obtained from HEK-293 cells (P>0.05). These results imply that anti-cancer efficacy of p28 is directly dependent on the presence of p53, suggesting p28 as an inappropriate therapeutic agent for treatment of cancers with negative p53 status.

Computer-aided drug repurposing for cancer therapy: Approaches and opportunities to challenge anticancer targets

Despite huge efforts made in academic and pharmaceutical worldwide research, current anticancer therapies achieve effective treatment in a limited number of neoplasia cases only. Oncology terms such as big killers - to identify tumours with yet a high mortality rate - or undruggable cancer targets, and chemoresistance, represent the current therapeutic debacle of cancer treatments. In addition, metastases, tumour microenvironments, tumour heterogeneity, metabolic adaptations, and immunotherapy resistance are essential features controlling tumour response to therapies, but still, lack effective therapeutics or modulators. In this scenario, where the pharmaceutical productivity and drug efficacy in oncology seem to have reached a plateau, the so-called drug repurposing - i.e. the use of old drugs, already in clinical use, for a different therapeutic indication - is an appealing strategy to improve cancer therapy. Opportunities for drug repurposing are often based on occasional observations or on time-consuming pre-clinical drug screenings that are often not hypothesis-driven. In contrast, in-silico drug repurposing is an emerging, hypothesis-driven approach that takes advantage of the use of big-data. Indeed, the extensive use of -omics technologies, improved data storage, data meaning, machine learning algorithms, and computational modeling all offer unprecedented knowledge of the biological mechanisms of cancers and drugs' modes of action, providing extensive availability for both disease-related data and drugs-related data. This offers the opportunity to generate, with time and cost-effective approaches, computational drug networks to predict, in-silico, the efficacy of approved drugs against relevant cancer targets, as well as to select better responder patients or disease' biomarkers. Here, we will review selected disease-related data together with computational tools to be exploited for the in-silico repurposing of drugs against validated targets in cancer therapies, focusing on the oncogenic signaling pathways activation in cancer. We will discuss how in-silico drug repurposing has the promise to shortly improve our arsenal of anticancer drugs and, likely, overcome certain limitations of modern cancer therapies against old and new therapeutic targets in oncology.

Intrinsic adriamycin resistance in p53-mutated breast cancer is related to the miR-30c/FANCF/REV1-mediated DNA damage response

Adriamycin(ADR) is still considered to be one of the most effective agents in the treatment of breast cancer (BrCa), its efficacy is compromised by intrinsic resistance or acquire characteristics of multidrug resistance. At present, there are few genetic alterations that can be exploited as biomarkers to guide targeted use of ADR in clinical. Therefore, exploring the determinants of ADR sensitivity is pertinent for their optimal clinical application. TP53 is the most frequently mutated gene in human BrCa, p53 mutation has been reported to be closely related to ADR resistance, whereas the underlying mechanisms that cause endogenous ADR resistance in p53-mutant BrCa cells are not completely understood. The aim of the present study was to investigate the potential roles of miRNA in the response to ADR in p53-mutated breast cancer. Here, we report that BrCa cells expressing mutp53 are more resistant to ADR than cells with wild-type p53 (wtp53). The DNA repair protein- Fanconi anemia complementation group F protein (FANCF) and the translesion synthesis DNA polymerase REV1 protein is frequently abundant in the context of mutant p53 of BrCa. By targeting two key factors, miR-30c increases the sensitivity of BrCa cells to ADR. Furthermore, p53 directly activates the transcription of miR-30c by binding to its promoter. Subsequent analyses revealed that p53 regulates REV1 and FANCF by modulating miR-30c expression. Mutation of the p53 abolished this response. Consistently, reduced miR-30c expression is highly correlated with human BrCa with p53 mutational status and is associated with poor survival. We propose that one of the pathways affected by mutant p53 to increase intrinsic resistance to ADR involves miR-30c downregulation and the consequent upregulation of FANCF and REV1. The novel miRNA-mediated pathway that regulates chemoresistance in breast cancer will facilitate the development of novel therapeutic strategies.

Methylation-regulated ZNF545 inhibits growth of the p53-mutant KYSE150 cell line by inducing p21 and Bax

The Krüppel-associated box zinc-finger protein 545 (ZNF545) was recently identified as a tumor suppressor in esophageal squamous cell carcinoma (ESCC). However, the role of ZNF545 in the tumorigenesis of esophageal cancer cells expressing loss-of-function mutant p53 has not been elucidated. In the present study, the role of ZNF545 in esophageal tumors and the p53-mutant ESCC cell line, KYSE150, was investigated. ZNF545 mRNA was significantly downregulated in tumors when compared with adjacent normal tissues. Methylated ZNF545 was detected in 76.6% of tumor tissues compared with 28.1% of adjacent normal tissues. Combined pharmacological treatment of KYSE150 cells with a demethylating reagent and deacetylase inhibitor restored the expression of ZNF545. Ectopic expression of ZNF545 activated p53 transcription and upregulated the protein expression levels of pivotal effectors p21 and Bax, which are associated with cell proliferation and apoptosis, respectively, in p53-mutant KYSE150 cells; while suppressing colony formation and inducing apoptosis. ZNF545 was therefore proposed as a potential tumor suppressor responsible for inhibiting the growth of p53-mutant ESCC cell lines. In addition, tumor-specific methylation of ZNF545 may represent an epigenetic diagnostic biomarker and a therapeutic target in patients with esophageal cancer.

Magnolol induces apoptosis in osteosarcoma cells via G0/G1 phase arrest and p53-mediated mitochondrial pathway

Osteosarcoma is a highly invasive primary malignancy of bone. Magnolol is biologically active, which shows antitumor effects in a variety of cancer cell lines. However, it has not been elucidated magnolol's effects on human osteosarcoma cells (HOC). This study aimed to determine antitumor activity of magnolol and illustrate the molecular mechanism in HOC. Magnolol showed significant inhibition effect of growth on MG-63 and 143B cells and induced apoptosis and cell cycle arrest at G0/G1. In osteosarcoma cells, magnolol upregulated expressions of proapoptosis proteins and suppressed expressions of antiapoptosis proteins. Additionally, under the pretreatment of pifithrin-a (PFT-a, a p53 inhibitor), the magnolol-induced apoptosis was significantly reversed. The results above indicated that magnolol induces apoptosis in osteosarcoma cells may via G0/G1 phase arrest and p53-mediated mitochondrial pathway.

Current status and new treatment approaches in TP53 mutated AML

Mutations in the essential tumor suppressor gene, TP53, are observed in only 5-10% of acute myeloid leukemia (AML) cases, but are highly associated with therapy-related AML and cases with complex karyotype. The mutational status of TP53 is a critical prognostic indicator, with dismal outcomes consistently observed across studies. Response rates to traditional cytotoxic chemotherapy are poor and long-term survival after allogeneic hematopoietic stem cell transplant is rare. Therapy with hypomethylating agents has resulted in a modest improvement in outcomes over intensive chemotherapy, but durable responses are seldom observed. In view of the intrinsic resistance to standard chemotherapies conferred by mutations in TP53, novel treatment approaches are required. In this review, we examine the current treatment landscape in TP53 mutated AML and discuss emerging therapeutic approaches currently under clinical investigation.

Multiple Defects Sensitize p53-Deficient Head and Neck Cancer Cells to the WEE1 Kinase Inhibition

The p53 gene is the most commonly mutated gene in solid tumors, but leveraging p53 status in therapy remains a challenge. Previously, we determined that p53 deficiency sensitizes head and neck cancer cells to AZD1775, a WEE1 kinase inhibitor, and translated our findings into a phase I clinical trial. Here, we investigate how p53 affects cellular responses to AZD1775 at the molecular level. We found that p53 modulates both replication stress and mitotic deregulation triggered by WEE1 inhibition. Without p53, slowing of replication forks due to replication stress is exacerbated. Abnormal, γH2AX-positive mitoses become more common and can proceed with damaged or underreplicated DNA. p53-deficient cells fail to properly recover from WEE1 inhibition and exhibit fewer 53BP1 nuclear bodies despite evidence of unresolved damage. A faulty G1-S checkpoint propagates this damage into the next division. Together, these deficiencies can intensify damages in each consecutive cell cycle in the drug. IMPLICATIONS: The data encourage the use of AZD1775 in combination with genotoxic modalities against p53-deficient head and neck squamous cell carcinoma.

Mutant p53 in cancer therapy-the barrier or the path

Since wild-type p53 is central for maintaining genomic stability and preventing oncogenesis, its coding gene TP53 is highly mutated in ~50% of human cancers, and its activity is almost abrogated in the rest of cancers. Approximately 80% of p53 mutations are single point mutations with several hotspot mutations. Besides loss of function and dominant-negative effect on the wild-type p53 activity, the hotspot p53 mutants also acquire new oncogenic functions, so-called 'gain-of-functions' (GOF). Because the GOF of mutant p53 is highly associated with late-stage malignance and drug resistance, these p53 mutants have become hot targets for developing novel cancer therapies. In this essay, we review some recent progresses in better understanding of the role of mutant p53 GOF in chemoresistance and the underlying mechanisms, and discuss the pros and cons of targeting mutant p53 for the development of anti-cancer therapies.