Clinical implications of the deregulated TP73 isoforms expression in cancer

LINC00963-FOSB-mediated transcription activation of UBE3C enhances radioresistance of breast cancer cells by inducing ubiquitination-dependent protein degradation of TP73

BACKGROUND

The ubiquitin protein ligase E3C (UBE3C) has been reported to play an oncogenic role in breast cancer (BRCA). This work further investigates the effect of UBE3C on the radioresistance of BRCA cells.

METHODS

Molecules linking to radioresistance in BRCA were identified by analyzing two GEO datasets, GSE31863 and GSE101920. UBE3C overexpression or knockdown was induced in parental or radioresistant BRCA cells, followed by irradiation treatment. The malignant properties of cells in vitro, and the growth and metastatic activity of cells in nude mice, were analyzed. Downstream target proteins, as well as upstream transcriptional regulators of UBE3C, were predicted by bioinformatics tools. Molecular interactions were confirmed by immunoprecipitation and immunofluorescence assays. Furthermore, artificial alterations of TP73 and FOSB were induced in the BRCA cells for functional rescue assays.

RESULTS

According to bioinformatics analyses, UBE3C expression was linked to radioresistance in BRCA. UBE3C knockdown in radioresistant BRCA cells reduced while its overexpression in parental BRCA cells increased the radioresistance of cells in vitro and in vivo. UBE3C, which induced ubiquitination-dependent protein degradation of TP73, was transcriptionally activated by FOSB. The radioresistance of cancer cells was blocked by TP73 overexpression or FOSB knockdown. Additionally, LINC00963 was found to be responsible for the recruitment of FOSB to the UBE3C promoter for transcription activation.

CONCLUSION

This work demonstrates that LINC00963 induces nuclear translocation of FOSB and the consequent transcription activation of UBE3C, which enhances radioresistance of BRCA cells by inducing ubiquitination-dependent protein degradation of TP73.

p53 and p63 Proteoforms Derived from Alternative Splicing Possess Differential Seroreactivity in Colorectal Cancer with Distinct Diagnostic Ability from the Canonical Proteins

Colorectal cancer (CRC) is the third most common cancer and the second most frequent cause of cancer-related death worldwide. The detection in plasma samples of autoantibodies against specific tumor-associated antigens has been demonstrated to be useful for the early diagnosis of CRC by liquid biopsy. However, new studies related to the humoral immune response in cancer are needed to enable blood-based diagnosis of the disease. Here, our aim was to characterize the humoral immune response associated with the different p53 and p63 proteoforms derived from alternative splicing and previously described as aberrantly expressed in CRC. Thus, here we investigated the diagnostic ability of the twelve p53 proteoforms and the eight p63 proteoforms described to date, and their specific N-terminal and C-terminal end peptides, by means of luminescence HaloTag beads immunoassays. Full-length proteoforms or specific peptides were cloned as HaloTag fusion proteins and their seroreactivity analyzed using plasma from CRC patients at stages I-IV (n = 31), individuals with premalignant lesions (n = 31), and healthy individuals (n = 48). p53γ, Δ40p53β, Δ40p53γ, Δ133p53γ, Δ160p53γ, TAp63α, TAp63δ, ΔNp63α, and ΔNp63δ, together with the specific C-terminal end α and δ p63 peptides, were found to be more seroreactive against plasma from CRC patients and/or individuals with premalignant lesions than from healthy individuals. In addition, ROC (receiver operating characteristic) curves revealed a high diagnostic ability of those p53 and p63 proteoforms to detect CRC and premalignant individuals (AUC higher than 85%). Finally, electrochemical biosensing platforms were employed in POC-like devices to investigate their usefulness for CRC detection using selected p53 and p63 proteoforms. Our results demonstrate not only the potential of these biosensors for the simultaneous analysis of proteoforms’ seroreactivity, but also their convenience and versatility for the clinical detection of CRC by liquid biopsy. In conclusion, we here show that p53 and p63 proteoforms possess differential seroreactivity in CRC patients in comparison to controls, distinctive from canonical proteins, which should improve the diagnostic panels for obtaining a blood-based biomarker signature for CRC detection.

Long non-coding RNA tumor protein 73 antisense RNA 1 influences an interaction between lysine demethylase 5A and promoter of tumor protein 73 to enhance the malignancy of colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide. The aim of the present study was to explore the expression level of tumor protein 73 (TP73) in highly malignant CRC tumors and how the long non-coding RNA tumor protein 73 antisense RNA 1 (TP73-AS1) influences that transcription. We found that TP73-AS1 was highly expressed in malignant CRC samples in The Cancer Genome Atlas (TCGA) database. We also demonstrated TP73-AS1 was expressed in thirty samples of CRC tissues collected from China Medical University patients as well as in HCT116, RKO and SW480 CRC cell lines but not in HCoEpiC or CCD-18Co normal colon cells. Only wild-type TP73-AS1, but not any of its alternate splicing isoforms, was positively correlated with tumor malignancy. TP73-AS1 transcripts were shown to be located in cell nuclei especially in close proximity to the TP73 promoter in CRC cells, but not in normal colon cells. In addition, an interaction between lysine demethylase 5A (KDM5A) and TP73-AS1 in CRC cells, but not normal colon cells, and KDM5A localization on the TP73 promoter were influenced by TP73-AS1. Interestingly, the H3K4me3 level on the TP73 promoter was reduced, but was elevated by TP73-AS1 knockdown in CRC cells. In conclusion, these results suggest a novel epigenetic role of TP73-AS1 on histone demethylation that influences TP73 transcription, and shed light on malignancy in CRC.

Overexpression of splicing factor poly(rC)-binding protein 1 elicits cycle arrest, apoptosis induction, and p73 splicing in human cervical carcinoma cells

PURPOSE

Splicing factor poly(rC)-binding protein 1 (PCBP1) is a novel tumor suppressor that is downregulated in several cancers thereby regulating tumor formation and metastasis. However, the involvement of PCBP1 in apoptosis of cancer cells and the molecular mechanism remains elusive. On this basis, we sought to investigate the role of splicing factor PCBP1 in the apoptosis in human cervical cancer cells.

METHODS

To investigate PCBP1 functions in vitro, we overexpressed PCBP1 in human cervical cancer cells. A series of cytological function assays were employed to study to the role of PCBP1 in cell proliferation, cell cycle arrest and apoptosis.

RESULTS

Overexpression of PCBP1 was found to greatly repress proliferation of HeLa cells in a time-dependent manner. It also induced a significant increase in G2/M phase arrest and apoptosis. Furthermore, overexpressed PCBP1 favored the production of long isoforms of p73, thereby inducing upregulated ratio of Bax/Bcl-2, the release of cytochrome c and the expression of caspase-3.

CONCLUSION

Our results revealed that PCBP1 played a vital role in p73 splicing, cycle arrest and apoptosis induction in human cervical carcinoma cells. Targeting PCBP1 may be a potential therapeutic strategy for cervical cancer therapy.

RENORT: a project to analyze patterns of care in radiation oncology in Spain

PURPOSE

RENORT is an application (app) developed to assess the role of radiotherapy in the treatment of cancer using the oncology information systems (OIS).

METHODS/PATIENTS

The RENORT app was used to analyze the data for all patients seen and/or treated at six radiation oncology departments in Spain in 2019. This app can be used to extract the demographic data, treatment sequence, disease status, and radiotherapy treatments from the ARIA and Mosaiq OIS.

RESULTS

A total of 6564 treatments were performed at these six centers in 2019. Most patients (56.9%) were males (females 43.1%). The mean patient age was 64.9 years. The most common treatment types and sites were as follows: metastases/palliative care (25.9%), followed by breast (19.0%), genitourinary (13.7%), lung (10.1%), head and neck (6.0%), rectal (6.0%), gynecological (4.9%), and other (< 4%) cancers. Distribution by disease stage was as follows: breast cancer: 75.5% early stage (stages 0, I, and II); lung: 63.1% advanced stage (III and IV); and head and neck: 72.1% advanced. Treatment intent was curative in 76.5% of cases and palliative in 23.5%. The most common techniques were intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) (41.4%), followed by three-dimensional conformal radiation therapy (3D-CRT) (39.2%); stereotactic body radiotherapy (SBRT) (8.1%); brachytherapy (5.5%); radiosurgery (2.1%); fractionated stereotactic radiotherapy to the brain (1.4%); and intraoperative radiotherapy (1.4%). Hypofractionation was used in 62.3% of curative treatments (mean number of fractions = 16.5).

CONCLUSIONS

RENORT is a free app that is available for the two main oncology information systems used in most radiation oncology departments. This app has demonstrated the capacity to extract data from these systems, which in turns allows for a comprehensive analysis and better understanding of the role of radiotherapy in the treatment of cancer.

In-depth proteomics characterization of ∆Np73 effectors identifies key proteins with diagnostic potential implicated in lymphangiogenesis, vasculogenesis and metastasis in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer‐related death worldwide. Alterations in proteins of the p53‐family are a common event in CRC. ΔNp73, a p53‐family member, shows oncogenic properties and its effectors are largely unknown. We performed an in‐depth proteomics characterization of transcriptional control by ∆Np73 of the secretome of human colon cancer cells and validated its clinical potential. The secretome was analyzed using high‐density antibody microarrays and stable isotopic metabolic labeling. Validation was performed by semiquantitative PCR, ELISA, dot‐blot and western blot analysis. Evaluation of selected effectors was carried out using 60 plasma samples from CRC patients, individuals carrying premalignant colorectal lesions and colonoscopy‐negative controls. In total, 51 dysregulated proteins were observed showing at least 1.5‐foldchange in expression. We found an important association between the overexpression of ∆Np73 and effectors related to lymphangiogenesis, vasculogenesis and metastasis, such as brain‐derived neurotrophic factor (BDNF) and the putative aminoacyl tRNA synthase complex‐interacting multifunctional protein 1 (EMAP‐II)–vascular endothelial growth factor C–vascular endothelial growth factor receptor 3 axis. We further demonstrated the usefulness of BDNF as a potential CRC biomarker able to discriminate between CRC patients and premalignant individuals from controls with high sensitivity and specificity.

Lactate Upregulates the Expression of DNA Repair Genes, Causing Intrinsic Resistance of Cancer Cells to Cisplatin

Intrinsic or acquired drug resistance is one of the major problems compromising the success of antineoplastic treatments. Several evidences correlated some therapeutic failures with changes in cell metabolic asset and in line with these findings, hindering the glycolytic metabolism of cancer cells via lactate dehydrogenase (LDH) inhibition was found to overcome the resistance to chemotherapeutic agents. Lactate, the product of LDH reaction, was shown to be involved in epigenetic regulation of gene expression. The experiments described in this paper were aimed at highlighting a possible direct effect of lactate in modifying the response of cancer cells to a chemotherapeutic treatment. To discriminate between the effects potentially caused by glycolytic metabolism from those directly referable to lactate, we selected cancer cell lines able to grow in glucose deprived conditions and evaluated the impact of lactate on the cellular response to cisplatin-induced DNA damage. In lactate-exposed cells we observed a reduced efficacy of cisplatin, which was associated with reduced signatures of DNA damage, enhanced DNA recombination competence and increased expression of a panel of genes involved in DNA repair. The identified genes take part in mismatch and nucleotide excision repair pathways, which were found to contribute in restoring the cisplatin-induced DNA damage. The obtained results suggest that this metabolite could play a role in reducing the efficacy of antineoplastic treatments.

Identifying and Validating of an Autophagy-Related Gene Signature for the Prediction of Early Relapse in Breast Cancer

BACKGROUND

Compelling evidence has demonstrated the pivotal role of autophagy in the prognosis of breast cancer. Breast cancer (BC) patients with early relapse consistently exhibited worse survival.

METHODS

The autophagy-related genes were derived from the Human Autophagy Database (HADb) and high-sequencing data were obtained from The Cancer Genome Atlas (TCGA). Discrepantly expressed autophagy genes (DEAGs) between early relapse and long-term survival groups were performed using the Linear Models for Microarray data (LIMMA) method. Lasso Cox regression analysis was conducted for the selection of the 4-gene autophagy-related gene signature. GSE42568 and GSE21653 databases were enrolled in this study for the external validation of the signature. Then patients were divided into high and low-risk groups based on the specific score formula. GSEA was used to discover the related signaling pathway. The Kaplan-Meier curves and the receiver operating characteristic (ROC) curves were used to evaluate the discrimination and accuracy of the 4-gene signature.

RESULTS

A signature composed of four autophagy-related mRNA including APOL1, HSPA8, SIRT1, and TP73, was identified as significantly associated with the early relapse in BC patients. Time-dependent receiver-operating characteristic at 1 year suggested remarkable accuracy of the signature [area under the curve (AUC = 0.748)]. The risk score model based on the autophagy-related signature showed favorable predicting value in 1-, 2-, and 3-year relapse-free survival (RFS) in training and two validating cohorts. The GSEA displayed gene sets were remarkably enriched in carcinogenic activation pathways and autophagy-related pathways. The nomogram involving three variables (progesterone receptor status, T stage, and 4-gene signature) exhibited relatively good discrimination with a C-index of 0.766.

CONCLUSIONS

Our study establishes an autophagy-related 4-gene signature that can effectively stratify the high-risk and low-risk BC patients for early relapse. Combined with the clinicopathological variables, the signature could significantly help oncologists tailor more efficient treatment strategies for BC patients.

D-SCRIPT translates genome to phenome with sequence-based, structure-aware, genome-scale predictions of protein-protein interactions

We combine advances in neural language modeling and structurally motivated design to develop D-SCRIPT, an interpretable and generalizable deep-learning model, which predicts interaction between two proteins using only their sequence and maintains high accuracy with limited training data and across species. We show that a D-SCRIPT model trained on 38,345 human PPIs enables significantly improved functional characterization of fly proteins compared with the state-of-the-art approach. Evaluating the same D-SCRIPT model on protein complexes with known 3D structure, we find that the inter-protein contact map output by D-SCRIPT has significant overlap with the ground truth. We apply D-SCRIPT to screen for PPIs in cow (Bos taurus) at a genome-wide scale and focusing on rumen physiology, identify functional gene modules related to metabolism and immune response. The predicted interactions can then be leveraged for function prediction at scale, addressing the genome-to-phenome challenge, especially in species where little data are available.

Identification of response signatures for tankyrase inhibitor treatment in tumor cell lines

Small-molecule tankyrase 1 and tankyrase 2 (TNKS1/2) inhibitors are effective antitumor agents in selected tumor cell lines and mouse models. Here, we characterized the response signatures and the in-depth mechanisms for the antiproliferative effect of tankyrase inhibition (TNKSi). The TNKS1/2-specific inhibitor G007-LK was used to screen 537 human tumor cell lines and a panel of particularly TNKSi-sensitive tumor cell lines was identified. Transcriptome, proteome, and bioinformatic analyses revealed the overall TNKSi-induced response signatures in the selected panel. TNKSi-mediated inhibition of wingless-type mammary tumor virus integration site/β-catenin, yes-associated protein 1 (YAP), and phosphatidylinositol-4,5-bisphosphate 3-kinase/AKT signaling was validated and correlated with lost expression of the key oncogene MYC and impaired cell growth. Moreover, we show that TNKSi induces accumulation of TNKS1/2-containing β-catenin degradasomes functioning as core complexes interacting with YAP and angiomotin proteins during attenuation of YAP signaling. These findings provide a contextual and mechanistic framework for using TNKSi in anticancer treatment that warrants further comprehensive preclinical and clinical evaluations.

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TNKSi-responding tumor cell lines were identified

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TNKSi targets WNT/β-catenin, YAP, and PI3K/AKT signaling

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Reduced MYC expression leads to impaired tumor cell growth

p53/p73 Protein Network in Colorectal Cancer and Other Human Malignancies

Simple Summary

The p53 family of proteins comprises p53, p63, and p73, which share high structural and functional similarity. The two distinct promoters of each locus, the alternative splicing, and the alternative translation initiation sites enable the generation of numerous isoforms with different protein-interacting domains and distinct activities. The co-expressed p53/p73 isoforms have significant but distinct roles in carcinogenesis. Their activity is frequently impaired in human tumors including colorectal carcinoma due to dysregulated expression and a dominant-negative effect accomplished by some isoforms and p53 mutants. The interactions between isoforms are particularly important to understand the onset of tumor formation, progression, and therapeutic response. The understanding of the p53/p73 network can contribute to the development of new targeted therapies.

Abstract

The p53 tumor suppressor protein is crucial for cell growth control and the maintenance of genomic stability. Later discovered, p63 and p73 share structural and functional similarity with p53. To understand the p53 pathways more profoundly, all family members should be considered. Each family member possesses two promoters and alternative translation initiation sites, and they undergo alternative splicing, generating multiple isoforms. The resulting isoforms have important roles in carcinogenesis, while their expression is dysregulated in several human tumors including colorectal carcinoma, which makes them potential targets in cancer treatment. Their activities arise, at least in part, from the ability to form tetramers that bind to specific DNA sequences and activate the transcription of target genes. In this review, we summarize the current understanding of the biological activities and regulation of the p53/p73 isoforms, highlighting their role in colorectal tumorigenesis. The analysis of the expression patterns of the p53/p73 isoforms in human cancers provides an important step in the improvement of cancer therapy. Furthermore, the interactions among the p53 family members which could modulate normal functions of the canonical p53 in tumor tissue are described. Lastly, we emphasize the importance of clinical studies to assess the significance of combining the deregulation of different members of the p53 family to define the outcome of the disease.

ΔNp73, TAp73 and Δ133p53 Extracellular Vesicle Cargo as Early Diagnosis Markers in Colorectal Cancer

Simple Summary

The survival of colorectal cancer patients largely relies on the stage at diagnosis. The identification of early and non-invasive biomarkers to be used in screening programs for the diagnosis of the disease at the premalignant stage is mandatory. The aim of this study is to validate in plasma-derived extracellular vesicles secreted by malignant cells the diagnostic potential of well-known tumor-associated genes, ΔNp73, TAp73, and Δ133p53, in healthy subjects (n = 29), individuals with premalignant lesions (n = 49), and colorectal cancer patients (n = 42). Our data support ΔNp73 levels contained in extracellular vesicles as such a non-invasive and premature biomarker for the early diagnosis of colorectal cancer.

Abstract

The early diagnosis of colorectal cancer is a key factor in the overall survival of the patients. The actual screening programs include different approaches with significant limitations such as unspecificity, high invasiveness, and detection at late stages of the disease. The specific content of extracellular vesicles derived from malignant cells may represent a non-invasive technique for the early detection of colorectal cancer. Here, we studied the mRNA levels of ΔNp73, TAp73, and Δ133p53 in plasma-derived extracellular vesicles from healthy subjects (n = 29), individuals with premalignant lesions (n = 49), and colorectal cancer patients (n = 42). Extracellular vesicles’ ΔNp73 levels were already significantly high in subjects with premalignant lesions. Δ133p53 levels were statistically increased in colorectal cancer patients compared to the other two groups and were associated with patients’ survival. Remarkably, TAp73 mRNA was not detected in any of the individuals. The evaluation of ΔNp73, Δ133p53 and CEA sensitivity, specificity and AUC values supports ΔNp73 as a better early diagnosis biomarker and CEA as the best to identify advanced stages. Thus, low levels of CEA and a high content of ΔNp73 may identify in screening programs those individuals at higher risk of presenting a premalignant lesion. In addition, Δ133p53 emerges as a potential prognosis biomarker in colorectal cancer.

Statistical and bioinformatic analysis of hemimethylation patterns in non-small cell lung cancer

Background

DNA methylation is an epigenetic event involving the addition of a methyl-group to a cytosine-guanine base pair (i.e., CpG site). It is associated with different cancers. Our research focuses on studying non-small cell lung cancer hemimethylation, which refers to methylation occurring on only one of the two DNA strands. Many studies often assume that methylation occurs on both DNA strands at a CpG site. However, recent publications show the existence of hemimethylation and its significant impact. Therefore, it is important to identify cancer hemimethylation patterns.

Methods

In this paper, we use the Wilcoxon signed rank test to identify hemimethylated CpG sites based on publicly available non-small cell lung cancer methylation sequencing data. We then identify two types of hemimethylated CpG clusters, regular and polarity clusters, and genes with large numbers of hemimethylated sites. Highly hemimethylated genes are then studied for their biological interactions using available bioinformatics tools.

Results

In this paper, we have conducted the first-ever investigation of hemimethylation in lung cancer. Our results show that hemimethylation does exist in lung cells either as singletons or clusters. Most clusters contain only two or three CpG sites. Polarity clusters are much shorter than regular clusters and appear less frequently. The majority of clusters found in tumor samples have no overlap with clusters found in normal samples, and vice versa. Several genes that are known to be associated with cancer are hemimethylated differently between the cancerous and normal samples. Furthermore, highly hemimethylated genes exhibit many different interactions with other genes that may be associated with cancer. Hemimethylation has diverse patterns and frequencies that are comparable between normal and tumorous cells. Therefore, hemimethylation may be related to both normal and tumor cell development.

Conclusions

Our research has identified CpG clusters and genes that are hemimethylated in normal and lung tumor samples. Due to the potential impact of hemimethylation on gene expression and cell function, these clusters and genes may be important to advance our understanding of the development and progression of non-small cell lung cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07990-7.

Altered Gene Expression Encoding Cytochines, Grow Factors and Cell Cycle Regulators in the Endometrium of Women with Chronic Endometritis

To evaluate the expression of genes encoding cytokines, grow factors and cell cycle regulators in the proliferative endometrium of women with chronic endometritis (CE) compared to controls. We performed a case-control study on seven women with CE as diagnosed by hysteroscopy and histology (Cases) compared to six women without CE (Controls). All women underwent diagnostic hysteroscopy plus endometrial biopsy during the mid-proliferative phase of the menstrual cycle. Endometrial samples were divided into two different aliquots for histological and molecular analyses. The endometrial expression profile of 16 genes encoding proteins involved in the inflammatory process, proliferation and cell cycle regulation/apoptosis was assessed by using high-throughput qPCR. Study endpoints were between-group differences in the expression of VEGF A, VEGF B, VEGF C, EGF, TNF, TGF B1, IFNG, TP73, TP73L, BAXva, CDC2, CDC2va, CCND3, CCNB1, BAX and IL12. RESULTS: VEGF A, VEGF B, VEGF C, EGF, TNF, TGF B1, IFNG, TP73, TP73L, BAXva, CDC2, CDC2va, CCND3, CCNB1 were significantly overexpressed in women with CE compared to controls, while BAX and IL12 had similar expression between groups. In women with CE, we found an altered endometrial expression of genes involved in inflammatory, cell proliferation, and apoptosis processes. The dominance of proliferative and anti-apoptotic activity in CE may potentially promote the development of polyps and hyperplastic lesions.

MCL1 binds and negatively regulates the transcriptional function of tumor suppressor p73

MCL1, an anti-apoptotic protein that controls chemosensitivity and cell fate through its regulation of intrinsic apoptosis, has been identified as a high-impact target in anti-cancer therapeutic development. With MCL1-specific inhibitors currently in clinical trials, it is imperative that we understand the roles that MCL1 plays in cells, especially when targeting the Bcl-2 homology 3 (BH3) pocket, the central region of MCL1 that mediates apoptotic regulation. Here, we establish that MCL1 has a direct role in controlling p73 transcriptional activity, which modulates target genes associated with DNA damage response, apoptosis, and cell cycle progression. This interaction is mediated through the reverse BH3 (rBH3) motif in the p73 tetramerization domain, which restricts p73 assembly on DNA. Here, we provide a novel mechanism for protein-level regulation of p73 transcriptional activity by MCL1, while also framing a foundation for studying MCL1 inhibitors in combination with platinum-based chemotherapeutics. More broadly, this work expands the role of Bcl-2 family signaling beyond cell fate regulation.

FDXR regulates TP73 tumor suppressor via IRP2 to modulate aging and tumor suppression

Ferredoxin reductase (FDXR) is a mitochondrial flavoprotein that initiates electron transport from NADPH to several cytochromes P450 via two electron carriers, ferredoxin 1 (FDX1) and FDX2. FDXR is the sole ferredoxin reductase in humans and plays a critical role in steroidogenesis and biosynthesis of heme and iron-sulfur clusters. However, much less is known about the role of FDXR in cancer. Here, we show that FDXR plays a role in tumorigenesis by modulating expression of the tumor suppressor p73. By using genetically modified mouse models, we recently showed that mice deficient in either Fdxr or Trp73 had a shorter lifespan and were prone to spontaneous tumors as compared with wild-type (WT) mice. Interestingly, compound Trp73 ^+/- ;Fdxr ^+/- mice lived longer and developed fewer tumors when compared with Fdxr ^+/- or Trp73 ^+/- mice. Moreover, we found that cellular senescence was increased in Trp73 ^+/- and Fdxr ^+/- mouse embryonic fibroblasts (MEFs), which was further increased in Trp73 ^+/- ;Fdxr ^+/- MEFs, as compared with that in WT MEFs. As FDXR is regulated by p73, we examined whether there was a feedback regulation between p73 and FDXR. Indeed, we found that Trp73 expression was decreased by loss of Fdxr in MEFs and that FDXR is required for p73 expression in multiple human cancer cell lines independent of p53. Mechanistically, we found that loss of FDXR, via FDX2, increased expression of iron-binding protein 2 (IRP2), which subsequently repressed TP73 mRNA stability. We also showed that TP73 transcript contained an iron response element in its 3'UTR, which was required for IRP2 to destabilize TP73 mRNA. Together, these data reveal a novel regulation of p73 by FDXR via IRP2 and that the FDXR-p73 axis plays a critical role in aging and tumor suppression. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Genome wide DNA methylation profiling identifies specific epigenetic features in high-risk cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer. Although most cSCCs have good prognosis, a subgroup of high-risk cSCC has a higher frequency of recurrence and mortality. Therefore, the identification of molecular risk factors associated with this aggressive subtype is of major interest. In this work we carried out a global-scale approach to investigate the DNA-methylation profile in patients at different stages, from premalignant actinic keratosis to low-risk invasive and high-risk non-metastatic and metastatic cSCC. The results showed massive non-sequential changes in DNA-methylome and identified a minimal methylation signature that discriminates between stages. Importantly, a direct comparison of low-risk and high-risk stages revealed epigenetic traits characteristic of high-risk tumours. Finally, a prognostic prediction model in cSCC patients identified a methylation signature able to predict the overall survival of patients. Thus, the analysis of DNA-methylation in cSCC revealed changes during the evolution of the disease through the different stages that can be of great value not only in the diagnosis but also in the prognosis of the disease.

DNA Methylation Activates TP73 Expression in Hepatocellular Carcinoma and Gastrointestinal Cancer

The complexity of TP73 expression and its functionality, as well as the role of TP73 in tumorigenesis, unlike its cousin TP53, which is an established tumor suppressor, have remained elusive to date. In this study, we isolated two stem cell lines (HepCY & HepCO) from normal young and old human liver tissues. We determined TP73 expression in HepCY and HepCO, hepatocellular cancer (HCC) cell lines (HepG2, SNU398, SNU449 and SNU475), gastrointestinal cancer (GI) cell lines (Caco2 and HCT116) and normal skin fibroblasts cell line (HS27). Immunohistochemical analyses of TP73 expression was also performed in non-cancerous and adjacent cancerous liver tissues of HCC patients. The results show that TP73 expression is exclusive to the cancer cell lines and not the adjacent normal liver tissues. Moreover, methylation-specific PCR and bisulfite sequencing studies revealed that TP73 promoter is activated only in cancer cell lines by DNA methylation. Furthermore, ChIP assay results demonstrated that a chromosomal networking protein (CTCF) and tumor protein p53 (TP53) bind to TP73 promoter and regulate TP73 expression. Our observations demonstrate that a positive correlation in tumorigenesis exists between TP73 expression and DNA methylation in promoter regions of TP73. These findings may prove significant for the development of future diagnostic and therapeutic applications.

The specific seroreactivity to ∆Np73 isoforms shows higher diagnostic ability in colorectal cancer patients than the canonical p73 protein

The p53-family is tightly regulated at transcriptional level. Due to alternative splicing, up to 40 different theoretical proteoforms have been described for p73 and at least 20 and 10 for p53 and p63, respectively. However, only the canonical proteins have been evaluated as autoantibody targets in cancer patients for diagnosis. In this study, we have cloned and expressed in vitro the most upregulated proteoforms of p73, ΔNp73α and ΔNp73β, for the analysis of their seroreactivity by a developed luminescence based immunoassay test using 145 individual plasma from colorectal cancer, premalignant individuals and healthy controls. ∆Np73α seroreactivity showed the highest diagnostic ability to discriminate between groups. The combination of ∆Np73α, ∆Np73β and p73 proteoforms seroreactivity were able to improve their individual diagnostic ability. Competitive inhibition experiments further demonstrated the presence of unique specific epitopes in ΔNp73 isoforms not present in p73, with several colorectal patients showing unique and specific seroreactivity to the ΔNp73 proteoforms. Overall, we have increased the complexity of the humoral immune response to the p53-family in cancer patients, showing that the proteoforms derived from the alternative splicing of p73 possess a higher diagnostic ability than the canonical protein, which might be extensive for p53 and p63 proteins.

TP73 is a credible biomarker for predicting clinical progression and prognosis in cervical cancer patients

Tumor protein p73 (TP73) has been reported to be dysregulated in various types of human cancer and associated with clinical progression and outcome. Owing to the lack of reports on the correlation between TP73 protein expression and clinicopathologic features of cervical cancer, the aim of our research was to explore the clinical and prognostic significance of TP73 protein expression in cervical cancer patients. In our study, TP73 protein expression was detected by immunochemistry in 118 paraffin-embedded cervical cancer tissue specimens and 40 paraffin-embedded normal cervical epithelium tissue specimens. In the results, we found cervical cancer tissues exhibited high TP73 expression in comparison with normal cervical epithelium tissues, which was consistent with the expression status of TP73 in The Cancer Genome Atlas (TCGA) database. Furthermore, we analyzed the relationships between TP73 expression and clinicopathologic features through using the chi-square test or Fisher’s exact test, and found high expression of TP73 was markedly associated with early clinical stage, less lymph node metastasis, absent distant metastasis, squamous cell carcinoma and favorable histological grade. The Kaplan–Meier method and log-rank test were performed based on the expression level of TP73 in a cervical cancer cohort from the TCGA database, and showed that TP73 expression was positively correlated with overall survival time in cervical cancer patients. Moreover, univariate and multivariate Cox proportional hazards regression model indicated that high TP73 expression was identified as an independent factor for predicting favorable overall survival in cervical cancer patients. In conclusion, TP73 expression is increased in cervical cancer tissues and cells, and acts as a credible biomarker for predicting favorable overall survival in cervical cancer patients.

TP73 G4C14-A4T14 polymorphism and cancer susceptibility: evidence from 36 case-control studies

G4C14-A4T14 polymorphism of TP73 gene has been reported with a potential association in cancer risks through affected cell homeostasis; however the results were not consistent. We performed a comprehensive meta-analysis to explore the associations between G4C14-A4T14 polymorphism and cancer susceptibility. Extensive retrieve was performed in PubMed, EMBASE, Google Scholar, Web of Science, Wanfang database and CNKI database up to May 20, 2018. Odds ratios (ORs) and 95% confidence intervals (CIs) were conducted to evaluate the overall strength of the associations in five genetic models, as well as in subgroup analyses. Q-test, false-positive report probability analysis and trial sequential analysis, Egger’s test and Begg’s funnel plot were applied to evaluate the robustness of the results. In silico analysis was managed to demonstrate the relationship of TP73 expression correlated with cancer tissues. Finally, 36 case–control studies with a total of 9493 cancer cases and 13,157 healthy controls were enrolled into the meta-analysis. The pooled results present a significantly higher risk of G4C14-A4T14 polymorphism in all the five genetic models, as well as in the subgroups of Caucasian, cervical cancer, colorectal cancer, H-B subgroup and comfort to Hardy–Weinberg equilibrium subgroup. In silico analysis revealed that the expression of TP73 in cervical cancer tissue is higher than it in corresponding normal tissue, as well as in cervical cancer. All in all, TP73 G4C14-A4T14 polymorphism causes an upgrade cancer risk, especially in Caucasian population. G4C14-A4T14 polymorphism might be a potential biomarker for judging the tumorigenesis of cervical cancer and colorectal cancer.