Mutant p53 Promotes Epithelial Ovarian Cancer by Regulating Tumor Differentiation, Metastasis, and Responsiveness to Steroid Hormones

Fatty acid metabolism-related lncRNA prognostic signature for serous ovarian carcinoma

Background: To explore the role of fatty acid metabolism (FAM)-related lncRNAs in the prognosis and antitumor immunity of serous ovarian cancer (SOC). Materials & methods: A SOC FAM-related lncRNA risk model was developed and evaluated by a series of analyses. Additional immune-related analyses were performed to further assess the associations between immune state, tumor microenvironment and the prognostic risk model. Results: Five lncRNAs associated with the FAM genes were found and used to create a predictive risk model. The patients with a low-risk profile exhibited favorable prognostic outcomes. Conclusion: The established prognostic risk model exhibits better predictive capabilities for the prognosis of patients with SOC and offers novel potential therapy targets for SOC.

Molecular profile is a strong predictor of the pattern of recurrence in patients with endometrial cancer

OBJECTIVES

To investigate the pattern of first recurrence of disease in patients with endometrial cancer according to molecular classification, and to assess the independent role of molecular profiling in each type of failure.

METHODS

Retrospective single-center study including patients diagnosed with endometrial cancer stage I-IVB (International Federation of Gynecology and Obstetrics 2009) between December 1994 and May 2022, who underwent primary surgical treatment and had a complete molecular profile. First recurrence was classified as isolated or multiple, and as vaginal, pelvic, peritoneal, nodal, and distant according to its location. The log-rank test and univariate and multivariate adjusted Cox regression models were used for comparison between groups.

RESULTS

A total of 658 patients were included. Recurrence was observed in 122 patients (18.5%) with a recurrence rate of 12.4% among mismatch-repair deficient tumors, 14.5% among non-specific molecular profile, 2.1% among POLE-mutated, and 53.7% among p53-abnormal tumors. Recurrences were found to be isolated in 80 (65.6%) and multiple in 42 (34.4%) patients, with no differences in molecular subtype (p=0.92). Patients with p53-abnormal tumors had a recurrence mainly as distant (28.4%) and peritoneal (21.1%) disease, while patients with non-specific molecular profile tumors presented predominantly with distant failures (10.3%), and mismatch-repair deficient tumors with locoregional recurrences (9.4%).On multivariate analysis, p53-abnormal molecular profile was the only independent risk factor for peritoneal failure (OR=8.54, 95% CI 2.0 to 36.3). Vaginal recurrence was independently associated with p53-abnormal molecular profile (OR=6.51, 95% CI 1.1 to 37.4) and lymphovascular space invasion. p53-abnormal and non-specific molecular profiles were independent predictors for distant recurrence (OR=3.13, 95% CI 1.1 to 8.7 and OR=2.35, 95% CI 1.1 to 5.0, respectively), along with lymphovascular space invasion and high-grade tumors. Molecular profile was not independently associated with pelvic and nodal recurrences.

CONCLUSIONS

Endometrial cancer featured different patterns of recurrence depending on the molecular profile. p53-abnormal molecular profiling was the only independent risk factor for peritoneal relapse, while non-specific molecular profile showed a strong association with distant failures.

Regulation of ULK1 by WTAP/IGF2BP3 axis enhances mitophagy and progression in epithelial ovarian cancer

There is a pressing need for innovative therapeutic strategies for patients with epithelial ovarian cancer (EOC). Previous studies have shown that UNC-51-like kinase 1 (ULK1), a serine/threonine kinase, is crucial in regulating cellular autophagy and mitophagy across various tumor types. However, the clinical implications, biological functions, and potential mechanisms of ULK1 in EOC remain poorly understood. This study demonstrates that ULK1 expression is upregulated in EOC tissue samples and EOC cell lines, with increased ULK1 expression correlating with poor prognosis. Functionally, overexpressed ULK1 enhances the proliferation and migration abilities of EOC cells both in vitro and in vivo. Mechanistically, ULK1 was identified as an m6A target of WTAP. WTAP-mediated m6A modification of ULK1 enhanced its mRNA stability in an IGF2BP3-dependent manner, leading to elevated ULK1 expression and enhanced mitophagy in EOC. In summary, our research reveals that the WTAP/IGF2BP3-ULK1 axis significantly influences protective mitophagy in EOC, contributing to its progression. Therefore, the regulatory mechanisms and biological function of ULK1 identify it as a potential molecular target for therapeutic intervention in EOC.

Biology-driven therapy advances in high-grade serous ovarian cancer

Following a period of slow progress, the completion of genome sequencing and the paradigm shift relative to the cell of origin for high grade serous ovarian cancer (HGSOC) led to a new perspective on the biology and therapeutic solutions for this deadly cancer. Experimental models were revisited to address old questions, and improved tools were generated. Additional pathways emerging as drivers of ovarian tumorigenesis and key dependencies for therapeutic targeting, in particular, VEGF-driven angiogenesis and homologous recombination deficiency, were discovered. Molecular profiling of histological subtypes of ovarian cancer defined distinct genetic events for each entity, enabling the first attempts toward personalized treatment. Armed with this knowledge, HGSOC treatment was revised to include new agents. Among them, PARP inhibitors (PARPis) were shown to induce unprecedented improvement in clinical benefit for selected subsets of patients. Research on mechanisms of resistance to PARPis is beginning to discover vulnerabilities and point to new treatment possibilities. This Review highlights these advances, the remaining challenges, and unsolved problems in the field.

P53 and TLR4 expression are prognostic markers informing progression free survival of advanced stage high grade serous ovarian cancer

OBJECTIVE

New prognostic biomarkers, and bio-signatures, are urgently needed to facilitate a precision medicine-based approach to more effectively treat patients with high-grade serous ovarian cancer (HGSC). In this study, we analysed the expression patterns of a series of candidate protein biomarkers.

METHODS

The panel of markers which included MyD88, TLR4, MAD2, PR, OR, WT1, p53, p16, CD10 and Ki67 was assessed using immunohistochemistry in a tissue microarray (TMA) cohort of n = 80 patients, composed of stage 3-4 HGSCs. Each marker was analysed for their potential to predict both overall survival (OS) and progression-free survival (PFS).

RESULTS

TLR4 and p53 were found to be individually predictive of poorer PFS (Log Rank, p = 0.017, p = 0.030 respectively). Cox regression analysis also identified high p53 and TLR4 expression as prognostic factors for reduced PFS (p53; HR=1.785, CI=1.036-3.074, p = 0.037 and TLR4; HR=2.175, CI=1.112-4.253, p = 0.023). Multivariate forward conditional Cox regression analysis, examining all markers, identified a combined signature composed of p53 and TLR4 as prognostic for reduced PFS (p = 0.023).

CONCLUSION

Combined p53 and TLR4 marker assessment may help to aid treatment stratification for patients diagnosed with advanced-stage HGSC.

Refined criteria for p53 expression in ovarian mucinous tumours are highly concordant with TP53 mutation status, but p53 expression/TP53 status lack prognostic significance

In gynecological neoplasms, immunohistochemical (IHC) expression of p53 is generally an accurate predictor of TP53 mutation status if correctly interpreted by the pathologist. However, the literature concerning cut-offs, frequency and prognostic significance of p53 staining in ovarian mucinous tumours is limited and heterogeneous. We performed an analysis of 123 primary ovarian mucinous tumours including mucinous borderline tumours (MBT), mucinous carcinomas (MC), and tumours with equivocal features between MBT and MC. We assessed p53 expression for the three recognised patterns of aberrant staining in ovarian carcinoma [overexpression ('all'), null and cytoplasmic] but using a recently suggested cut-off for aberrant overexpression in ovarian mucinous tumours (strong nuclear p53 staining in ≥12 consecutive tumour cells) and correlated the results with next generation sequencing (NGS) in all qualitatively sufficient cases (92/123). Aberrant p53 expression was present in 25/75 (33.3%) MBT, 23/33 (69.7%) MC (75% of MC with expansile invasion and 61.5% with infiltrative invasion), and 10/15 (66.7%) tumours equivocal between MBT and MC. Regarding the 92 tumours with paired IHC and mutation results, 86 showed concordant results and six cases were discordant. Three discordant MBT cases showed aberrant expression but were TP53 wild-type on sequencing. Three cases had normal p53 expression but contained a TP53 mutation. Overall, IHC predicted the TP53 mutation status with high sensitivity (94.1%) and specificity (92.7%). The accuracy of IHC was 93.5% with a positive predictive value of 94.1% and a negative predictive value of 92.7%. When comparing MC cases with wild-type TP53 versus those with TP53 mutation, there were no significant differences concerning disease-free survival, local recurrence-free survival, or metastases-free survival (p>0.05). In the MBT subgroup, there were no events for survival analyses. In conclusion, using an independent large sample set of ovarian mucinous tumours, the results of our study confirm that the suggested refined cut-off of strong nuclear p53 staining in ≥12 consecutive tumour cells reflect high accuracy, sensitivity and specificity for an underlying TP53 mutation but the TP53 mutation status has no prognostic significance in either MC or MBT.

RNA sequencing and expression analysis reveal a role for Lhx9 in the haploinsufficient adult mouse ovary

Understanding the molecular pathways that underpin ovarian development and function is vital for improving the research approaches to investigating fertility. Despite a significant improvement in our knowledge of molecular activity in the ovary, many questions remain unanswered in the quest to understand factors influencing fertility and ovarian pathologies such as cancer. Here, we present an investigation into the expression and function of the developmental transcription factor LIM Homeobox 9 (LHX9) in the adult mouse ovary. We have characterized Lhx9 expression in several cell types of the mature ovary across follicle stages. To evaluate possible LHX9 function in the adult ovary, we investigated ovarian anatomy and transcription in an Lhx9^+/- knockout mouse model displaying subfertility. Despite a lack of gross anatomical differences between genotypes, RNA-sequencing found that 90 differentially expressed genes between Lhx9^{+/ -} and Lhx9^+/+ mice. Gene ontology analyses revealed a reduced expression of genes with major roles in ovarian steroidogenesis and an increased expression of genes associated with ovarian cancer. Analysis of the ovarian epithelium revealed Lhx9^{+/ -} mice have a disorganized epithelial phenotype, corresponding to a significant increase in epithelial marker gene expression. These results provide an analysis of Lhx9 in the adult mouse ovary, suggesting a role in fertility and ovarian epithelial cancer.

Primary Mucinous Tumors of the Ovary: An Interobserver Reproducibility and Detailed Molecular Study Reveals Significant Overlap Between Diagnostic Categories

Primary ovarian mucinous tumors represent a heterogeneous group of neoplasms, and their diagnosis may be challenging. We analyzed 124 primary ovarian mucinous tumors originally diagnosed as mucinous borderline tumors (MBTs) or mucinous carcinomas (MCs), with an emphasis on interobserver diagnostic agreement and the potential for diagnostic support by molecular profiling using a next-generation sequencing targeted panel of 727 DNA and 147 RNA genes. Fourteen experienced pathologists independently assigned a diagnosis from preset options, based on a review of a single digitized slide from each tumor. After excluding 1 outlier participant, there was a moderate agreement in diagnosing the 124 cases when divided into 3 categories (κ = 0.524, for mucinous cystadenoma vs MBT vs MC). A perfect agreement for the distinction between mucinous cystadenoma/MBT as a combined category and MC was found in only 36.3% of the cases. Differentiating between MBTs and MCs with expansile invasion was particularly problematic. After a reclassification of the tumors into near-consensus diagnostic categories on the basis of the initial participant results, a comparison of molecular findings between the MBT and MC groups did not show major and unequivocal differences between MBTs and MCs or between MCs with expansile vs infiltrative pattern of invasion. In contrast, HER2 overexpression or amplification was found only in 5.3% of MBTs and in 35.3% of all MCs and in 45% of MCs with expansile invasion. Overall, HER2 alterations, including mutations, were found in 42.2% of MCs. KRAS mutations were found in 65.5% and PIK3CA mutations in 6% of MCs. In summary, although the diagnostic criteria are well-described, diagnostic agreement among our large group of experienced gynecologic pathologists was only moderate. Diagnostic categories showed a molecular overlap. Nonetheless, molecular profiling may prove to be therapeutically beneficial in advanced-stage, recurrent, or metastatic MCs.

Progress in Anticancer Drug Development Targeting Ubiquitination-Related Factors

Ubiquitination is extensively involved in critical signaling pathways through monitoring protein stability, subcellular localization, and activity. Dysregulation of this process results in severe diseases including malignant cancers. To develop drugs targeting ubiquitination-related factors is a hotspot in research to realize better therapy of human diseases. Ubiquitination comprises three successive reactions mediated by Ub-activating enzyme E1, Ub-conjugating enzyme E2, and Ub ligase E3. As expected, multiple ubiquitination enzymes have been highlighted as targets for anticancer drug development due to their dominant effect on tumorigenesis and cancer progression. In this review, we discuss recent progresses in anticancer drug development targeting enzymatic machinery components.

Aberrant MAPK Signaling Offers Therapeutic Potential for Treatment of Ovarian Carcinoma

Ovarian cancer remains the most lethal gynecological malignancy worldwide due to lack of effective screening, vague early symptoms, poor description of biomarkers, and absence of effective treatment regimes. Epithelial ovarian carcinoma (EOC) is categorized into five distinct disease subtypes which collectively account for ~90% of ovarian carcinomas. Most women present at advanced stages contributing to a poor overall 5-year survival rate. Standard treatment for EOC is cytoreductive surgery and platinum-based chemotherapy; however, most patients suffer from recurrence and platinum-resistant disease, which highlights an urgent need for targeted therapy. The high frequency of molecular alterations affecting gain-of-function signaling through the RAS mitogen-activated protein kinase (MAPK) pathway in EOC has prompted pre-clinical and clinical efforts toward research into the effectiveness of MAPK pathway inhibition as a second-line treatment. The RAS/MAPK pathway is a highly conserved signal transduction cascade, often disrupted in cancer, that regulates tumorigenic phenotypes including cellular proliferation, survival, migration, apoptosis, and differentiation. Herein, the role of the MAPK pathway in EOC with emphasis on targetability of the pathway is described. Pre-clinical and clinical efforts to target MAPK signaling in EOC have identified several MAPK pathway inhibitors that offer efficacious potential for monotherapy and in combination with other compounds. Thus, inhibition of the RAS/MAPK pathway is emerging as a tractable strategy for treatment of ovarian cancer that may permit development of personalized therapy and improved prognosis for women challenged by this disease.

Harnessing preclinical models for the interrogation of ovarian cancer

Ovarian cancer (OC) is a heterogeneous malignancy with various etiology, histopathology, and biological feature. Despite accumulating understanding of OC in the post-genomic era, the preclinical knowledge still undergoes limited translation from bench to beside, and the prognosis of ovarian cancer has remained dismal over the past 30 years. Henceforth, reliable preclinical model systems are warranted to bridge the gap between laboratory experiments and clinical practice. In this review, we discuss the status quo of ovarian cancer preclinical models which includes conventional cell line models, patient-derived xenografts (PDXs), patient-derived organoids (PDOs), patient-derived explants (PDEs), and genetically engineered mouse models (GEMMs). Each model has its own strengths and drawbacks. We focus on the potentials and challenges of using these valuable tools, either alone or in combination, to interrogate critical issues with OC.

The senescence-associated secretory phenotype in ovarian cancer dissemination

Ovarian cancer is a highly aggressive disease with poor survival rates in part due to diagnosis after dissemination throughout the peritoneal cavity. It is well-known that inflammatory signals affect ovarian cancer dissemination. Inflammation is a hallmark of cellular senescence, a stable cell cycle arrest induced by a variety of stimuli including many of the therapies used to treat patients with ovarian cancer. Indeed, recent work has illustrated that ovarian cancer cells in vitro, mouse models, and patient tumors undergo senescence in response to platinum-based or poly(ADP-ribose) polymerase (PARP) inhibitor therapies, standard-of-care therapies for ovarian cancer. This inflammatory response, termed the senescence-associated secretory phenotype (SASP), is highly dynamic and has pleiotropic roles that can be both beneficial and detrimental in cell-intrinsic and cell-extrinsic ways. Recent data on other cancer types suggest that the SASP promotes metastasis. Here, we outline what is known about the SASP in ovarian cancer and discuss both how the SASP may promote ovarian cancer dissemination and strategies to mitigate the effects of the SASP.

Preclinical models of epithelial ovarian cancer: practical considerations and challenges for a meaningful application

Despite many improvements in ovarian cancer diagnosis and treatment, until now, conventional chemotherapy and new biological drugs have not been shown to cure the disease, and the overall prognosis remains poor. Over 90% of ovarian malignancies are categorized as epithelial ovarian cancers (EOC), a collection of different types of neoplasms with distinctive disease biology, response to chemotherapy, and outcome. Advances in our understanding of the histopathology and molecular features of EOC subtypes, as well as the cellular origins of these cancers, have given a boost to the development of clinically relevant experimental models. The overall goal of this review is to provide a comprehensive description of the available preclinical investigational approaches aimed at better characterizing disease development and progression and at identifying new therapeutic strategies. Systems discussed comprise monolayer (2D) and three-dimensional (3D) cultures of established and primary cancer cell lines, organoids and patient-derived explants, animal models, including carcinogen-induced, syngeneic, genetically engineered mouse, xenografts, patient-derived xenografts (PDX), humanized PDX, and the zebrafish and the laying hen models. Recent advances in tumour-on-a-chip platforms are also detailed. The critical analysis of strengths and weaknesses of each experimental model will aid in identifying opportunities to optimize their translational value.

Deciphering the Increased Prevalence of TP53 Mutations in Metastatic Prostate Cancer

The prevalence of TP53 mutations in advanced prostate cancers (PCa) is 3 to 5 times of the quantity in primary PCa. By an integrative analysis of the Cancer Genome Atlas and Catalogue of Somatic Mutations in Cancer data, we revealed the supporting evidence for 2 complementary hypotheses: H₁ - TP53 abnormalities promote metastasis or therapy-resistance of PCa cells, and H₂—part of TP53 mutations in PCa metastases occur after the diagnosis of original cancers. The plausibility of these hypotheses can explain the increased prevalence of TP53 mutations in PCa metastases. With H₁ and H₂ as the general assumptions, we developed mathematical models to decipher the change of the percentage frequency (prevalence) of TP53 mutations from primary tumors to metastases. The following results were obtained. Compared to TP53-normal patients, TP53-mutated patients had poorer biochemical relapse-free survival, higher Gleason scores, and more advanced t-stages (P < .01). Single-nucleotide variants in metastases more frequently occurred on G bases of the coding sequence than those in primary cancers (P = .03). The profile of TP53 hotspot mutations was significantly different between primary and metastatic PCa as demonstrated in a set of statistical tests (P < .05). By the derived formulae, we estimated that about 40% TP53 mutation records collected from metastases occurred after the diagnosis of the original cancers. Our study provided significant insight into PCa progression. The proposed models can also be applied to decipher the prevalence of mutations on TP53 (or other driver genes) in other cancer types.

Estrogen Receptor-Beta2 (ERβ2)-Mutant p53-FOXM1 Axis: A Novel Driver of Proliferation, Chemoresistance, and Disease Progression in High Grade Serous Ovarian Cancer (HGSOC)

Simple Summary

High grade serous ovarian cancer (HGSOC) is the most common and lethal subtype of ovarian cancer without effective therapeutic options. The high prevalence of mutations (~96%) in tumor suppressor p53 is a hallmark of HGSOC. Estrogen receptor-beta (ERβ) has been reported to be another important player in HGSOC, although the pro-versus anti-tumorigenic role of its different isoforms remains unclear. The aim of this study was to analyze the crosstalk between ERβ and mutant p53 and its impact on the pro-tumorigenic processes in HGSOC. Using the HGSOC cell line models and patient tumor tissue specimens, we demonstrated functional interaction between the ERβ2 isoform and mutant p53 and their ability to co-dependently increase FOXM1 gene transcription, decrease cell death, increase cell proliferation, and mediate resistance to carboplatin treatment. Furthermore, high levels of ERβ2 as well as FOXM1 correlated with worse patient survival. Collectively, our data suggest that the ERβ2-mutant p53-FOXM1 axis could be a novel therapeutic target for HGSOC.

Abstract

High grade serous ovarian cancer (HGSOC) is the most common and lethal subtype of epithelial ovarian cancer. Prevalence (~96%) of mutant p53 is a hallmark of HGSOC. Estrogen receptor-beta (ERβ) has been reported to be another important player in HGSOC, although the pro-versus anti-tumorigenic role of its different isoforms remains unsettled. However, whether there is functional interaction between ERβ and mutant p53 in HGSOC is unknown. ERβ1 and ERβ2 mRNA and protein analysis in HGSOC cell lines demonstrated that ERβ2 is the predominant isoform in HGSOC. Specificity of ERβ2 antibody was ascertained using cells depleted of ERβ2 and ERβ1 separately with isoform-specific siRNAs. ERβ2-mutant p53 interaction in cell lines was confirmed by co-immunoprecipitation and in situ proximity ligation assay (PLA). Expression levels of ERβ2, ERα, p53, and FOXM1 proteins and ERβ2-mutant p53 interaction in patient tumors were determined by immunohistochemistry (IHC) and PLA, respectively. ERβ2 levels correlate positively with FOXM1 levels and negatively with progression-free survival (PFS) and overall survival (OS). Quantitative chromatin immunoprecipitation (qChIP) and mRNA expression analysis revealed that ERβ2 and mutant p53 co-dependently regulated FOXM1 gene transcription. The combination of ERβ2-specific siRNA and PRIMA-1^MET that converts mutant p53 to wild type conformation increased apoptosis. Our work provides the first evidence for a novel ERβ2-mutant p53-FOXM1 axis that can be exploited for new therapeutic strategies against HGSOC.

Identification of GNA12-driven gene signatures and key signaling networks in ovarian cancer

With the focus on defining the oncogenic network stimulated by lysophosphatidic acid (LPA) in ovarian cancer, the present study sought to interrogate the oncotranscriptome regulated by the LPA-mediated signaling pathway. LPA, LPA-receptor (LPAR) and LPAR-activated G protein 12 α-subunit, encoded by G protein subunit α 12 (GNA12), all serve an important role in ovarian cancer progression. While the general signaling mechanism regulated by LPA/LPAR/GNA12 has previously been characterized, the global transcriptomic network regulated by GNA12 in ovarian cancer pathophysiology remains largely unknown. To define the LPA/LPAR/GNA12-orchestrated oncogenic networks in ovarian cancer, transcriptomic and bioinformatical analyses were conducted using SKOV3 cells, in which the expression of GNA12 was silenced. Array analysis was performed in Agilent SurePrint G3 Human Comparative Genomic Hybridization 8×60 microarray platform. The array results were validated using Kuramochi cells. Gene and functional enrichment analyses were performed using Database for Annotation, Visualization and Integrated Discovery, Search Tool for Retrieval of Interacting Genes and Cytoscape algorithms. The results indicated a paradigm in which GNA12 drove ovarian cancer progression by upregulating a pro-tumorigenic network with AKT1, VEGFA, TGFB1, BCL2L1, STAT3, insulin-like growth factor 1 and growth hormone releasing hormone as critical hub and/or bottleneck nodes. Moreover, GNA12 downregulated a growth-suppressive network involving proteasome 20S subunit (PSM) β6, PSM α6, PSM ATPase 5, ubiquitin conjugating enzyme E2 E1, PSM non-ATPase 10, NDUFA4 mitochondrial complex-associated, NADH:ubiquinone oxidoreductase subunit B8 and anaphase promoting complex subunit 1 as hub or bottleneck nodes. In addition to providing novel insights into the LPA/LPAR/GNA12-regulated oncogenic networks in ovarian cancer, the present study identified several potential nodes in this network that could be assessed for targeted therapy.

Inactivation of TRP53, PTEN, RB1, and/or CDH1 in the ovarian surface epithelium induces ovarian cancer transformation and metastasis

Ovarian cancer (OvCa) remains the most common cause of death from gynecological malignancies. Genetically engineered mouse models have been used to study initiation, origin, progression, and/or mechanisms of OvCa. Based on the clinical features of OvCa, we examined a quadruple combination of pathway perturbations including PTEN, TRP53, RB1, and/or CDH1. To characterize the cancer-promoting events in the ovarian surface epithelium (OSE), Amhr2cre/+ mice were used to ablate floxed alleles of Pten, Trp53, and Cdh1, which were crossed with TgK19GT121 mice to inactivate RB1 in KRT19-expressing cells. Inactivation of PTEN, TRP53, and RB1 with or without CDH1 led to the development of type I low-grade OvCa with enlarged serous papillary carcinomas and some high-grade serous carcinomas (HGSCs) in older mice. Initiation of epithelial hyperplasia and micropapillary carcinoma started earlier at 1 month in the triple mutations of Trp53, Pten, and Rb1 mice as compared to 2 months in quadruple mutations of Trp53, Pten, Rb1, and Cdh1 mice, whereas both genotypes eventually developed enlarged proliferating tumors that invaded into the ovary at 3-4 months. Mice with triple and quadruple mutations developed HGSC and/or metastatic tumors, which disseminated into the peritoneal cavity at 4-6 months. In summary, inactivation of PTEN, TRP53, and RB1 initiates OvCa from the OSE. Additional ablation of CDH1 further increased persistence of tumor dissemination and ascites fluid accumulation enhancing peritoneal metastasis.

Polyploid giant cancer cells and ovarian cancer: new insights into mitotic regulators and polyploidy†

Current first-line treatment of patients with high-grade serous ovarian cancer (HGSOC) involves the use of cytotoxic drugs that frequently lead to recurrent tumors exhibiting increased resistance to the drugs and poor patient survival. Strong evidence is accumulating to show that HGSOC tumors and cell lines contain a subset of cells called polyploidy giant cancer cells (PGCCs) that act as stem-like, self-renewing cells. These PGCCs appear to play a key role in tumor progression by generating drug-resistant progeny produced, in part, as a consequence of utilizing a modified form of mitosis known as endoreplication. Thus, developing drugs to target PGCCs and endoreplication may be an important approach for reducing the appearance of drug-resistant progeny. In the review, we discuss newly identified regulatory factors that impact mitosis and which may be altered or repurposed during endoreplication in PGCCs. We also review recent papers showing that a single PGCC can give rise to tumors in vivo and spheroids in culture. To illustrate some of the specific features of PGCCs and factors that may impact their function and endoreplication compared to mitosis, we have included immunofluorescent images co-localizing p53 and specific mitotic regulatory, phosphoproteins in xenografts derived from commonly used HGSOC cell lines.

Cellular models of development of ovarian high-grade serous carcinoma: A review of cell of origin and mechanisms of carcinogenesis

High-grade serous carcinoma (HGSC) is the most common and malignant histological type of epithelial ovarian cancer, the origin of which remains controversial. Currently, the secretory epithelial cells of the fallopian tube are regarded as the main origin and the ovarian surface epithelial cells as a minor origin. In tubal epithelium, these cells acquire TP53 mutations and expand to a morphologically normal 'p53 signature' lesion, transform to serous tubal intraepithelial carcinoma and metastasize to the ovaries and peritoneum where they develop into HGSC. This shifting paradigm of the main cell of origin has revolutionarily changed the focus of HGSC research. Various cell lines have been derived from the two cellular origins by acquiring immortalization via overexpression of hTERT plus disruption of TP53 and the CDK4/RB pathway. Malignant transformation was achieved by adding canonical driver mutations (such as gain of CCNE1) revealed by The Cancer Genome Atlas or by noncanonical gain of YAP and miR181a. Alternatively, because of the extreme chromosomal instability, spontaneous transformation can be achieved by long passage of murine immortalized cells, whereas in humans, it requires ovulatory follicular fluid, containing regenerating growth factors to facilitate spontaneous transformation. These artificially and spontaneously transformed cell systems in both humans and mice have been widely used to discover carcinogens, oncogenic pathways and malignant behaviours in the development of HGSC. Here, we review the origin, aetiology and carcinogenic mechanism of HGSC and comprehensively summarize the cell models used to study this fatal cancer having multiple cells of origin and overt genomic instability.

BCL7C suppresses ovarian cancer growth by inactivating mutant p53

B-cell CLL/lymphoma 7 protein family member C (BCL7C) located at chromosome 16p11.2 shares partial sequence homology with the other two family members, BCL7A and BCL7B. Its role in cancer remains completely unknown. Here, we report our finding of its tumor-suppressive role in ovarian cancer. Supporting this is that BCL7C is downregulated in human ovarian carcinomas, and its underexpression is associated with unfavorable prognosis of ovarian cancer as well as some other types of human cancers. Also, ectopic BCL7C restrains cell proliferation and invasion of ovarian cancer cells. Consistently, depletion of BCL7C reduces apoptosis and promotes cell proliferation and invasion of these cancer cells. Mechanistically, BCL7C suppresses mutant p53-mediated gene transcription by binding to mutant p53, while knockdown of BCL7C enhances the expression of mutant p53 target genes in ovarian cancer cells. Primary ovarian carcinomas that sustain low levels of BCL7C often show the elevated expression of mutant p53 target genes. In line with these results, BCL7C abrogates mutant p53-induced cell proliferation and invasion, but had no impact on proliferation and invasion of cancer cells with depleted p53 or harboring wild-type p53. Altogether, our results demonstrate that BCL7C can act as a tumor suppressor to prevent ovarian tumorigenesis and progression by counteracting mutant p53 activity.

The hallmarks of ovarian cancer: proliferation and cell growth

Epithelial ovarian cancer (EOC) is a heterogeneous group of diseases with distinct biological and clinical behaviour. Despite the differences between them, the capability of tumour cells to continuously proliferate and avoid death is maintained among histotypes. This ability is the result of alterations at different levels, causing the deregulation of cell cycle and proliferative-related pathways. Even if the leading role is played by RB and TP53, changes in other molecular pathways are involved in the development of EOC. This ability can be exploited to generate in vitro and in vivo models resembling the conditions of tumour development in a patient. In vivo models, such as patient-derived xenografts (PDX) or genetically engineered mouse models (GEMM), represent a fundamental tool in the study of the molecular mechanisms implicated in each EOC biotype for testing new therapeutic approaches. Herein we describe the major proliferation-related pathways and its disruption found in EOC and how these features can be used to establish in vivo models for translational research.

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Epithelial ovarian cancer (EOC) molecular biotypes are defined by distinct biology and clinical behaviour.

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Sustained proliferation and resistance to cell death mechanisms characterised tumour cells.

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RB and TP53 tumour-suppressor genes are highly implicated in EOC pathogenesis.

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In vitro and in vivo models have a key role in the study of molecular mechanisms involved in EOC pathogenesis.

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Development of animal models that mimic disease features constitute essential tools for new drugs testing.

Ubiquitin ligase DTX3 empowers mutant p53 to promote ovarian cancer development

The deltex family protein DTX3 is believed to possess E3 ubiquitin ligase activity, as it contains a classic RING finger domain. However, its biological role and the underlying mechanism in cancer remain largely elusive. Here, we identified DTX3 as a novel mutant p53-interacting protein in ovarian carcinoma. Mechanistically, DTX3 mediated mutant p53 ubiquitination and stabilization by perturbing the MDM2-mutant p53 interaction, consequently leading to activation of diverse mutant p53 target genes. Importantly, a positive correlation between the expression of DTX3 and mutant p53 target genes was further validated in ovarian carcinomas. Ectopic DTX3 promoted, while depletion of DTX3 suppressed, ovarian cancer cell proliferation and invasion. Remarkably, the pro-tumorigenic effect of DTX3 is dependent on mutant p53, because ablation of mutant p53 significantly impaired DTX3-induced gene expression and ovarian cancer cell growth and propagation. Furthermore, DTX3 elevated the expression of mutant p53 target genes and boosted ovarian tumor growth in vivo. Finally, DTX3 was amplified and overexpressed in ovarian carcinomas, which is significantly associated with unfavorable prognosis. Altogether, our findings unveil the oncogenic role of DTX3 in ovarian cancer development by bolstering mutant p53 activity.

Murine Cytomegalovirus M25 Proteins Sequester the Tumor Suppressor Protein p53 in Nuclear Accumulations

To ensure productive infection, herpesviruses utilize tegument proteins and nonstructural regulatory proteins to counteract cellular defense mechanisms and to reprogram cellular pathways. The M25 proteins of mouse cytomegalovirus (MCMV) belong to the betaherpesvirus UL25 gene family that encodes viral proteins implicated with regulatory functions. Through affinity purification and mass spectrometric analysis, we discovered the tumor suppressor protein p53 as a host factor interacting with the M25 proteins. M25-p53 interaction in infected and transfected cells was confirmed by coimmunoprecipitation. Moreover, the proteins colocalized in nuclear dot-like structures upon both infection and inducible expression of the two M25 isoforms. p53 accumulated in wild-type MCMV-infected cells, while this did not occur upon infection with a mutant lacking the M25 gene. Both M25 proteins were able to mediate the effect, identifying them as the first CMV proteins responsible for p53 accumulation during infection. Interaction with M25 proteins led to substantial prolongation of the half-life of p53. In contrast to the higher abundance of the p53 protein in wild-type MCMV-infected cells, the transcript levels of the prominent p53 target genes Cdkn1a and Mdm2 were diminished compared to cells infected with the ΔM25 mutant, and this was associated with reduced binding of p53 to responsive elements within the respective promoters. Notably, the productivity of the M25 deletion mutant was partially rescued on p53-negative fibroblasts. We propose that the MCMV M25 proteins sequester p53 molecules in the nucleus of infected cells, reducing their availability for activating a subset of p53-regulated genes, thereby dampening the antiviral role of p53.IMPORTANCE Host cells use a number of factors to defend against viral infection. Viruses are, however, in an arms race with their host cells to overcome these defense mechanisms. The tumor suppressor protein p53 is an important sensor of cell stress induced by oncogenic insults or viral infections, which upon activation induces various pathways to ensure the integrity of cells. Viruses have to counteract many functions of p53, but complex DNA viruses such as cytomegaloviruses may also utilize some p53 functions for their own benefit. In this study, we discovered that the M25 proteins of mouse cytomegalovirus interact with p53 and mediate its accumulation during infection. Interaction with the M25 proteins sequesters p53 molecules in nuclear dot-like structures, limiting their availability for activation of a subset of p53-regulated target genes. Understanding the interaction between viral proteins and p53 may allow to develop new therapeutic strategies against cytomegalovirus and other viruses.

WOMEN IN REPRODUCTIVE SCIENCE: Discovering science and the ovary: a career of joy

My career has been about discovering science and learning the joys of the discovery process itself. It has been a challenging but rewarding process filled with many exciting moments and wonderful colleagues and students. Although I went to college to become a French major, I ultimately stumbled into research while pursuing a Masters Degree in teaching. Thus, my research career began in graduate school where I was studying NAD kinase in the ovary as a possible regulator of steroidogenesis, a big issue in the late 1960s. After a short excursion of teaching in North Dakota, I became a postdoctoral fellow at the University of Michigan, where radio-immuno assays and radio receptor assays had just come on the scene and were transforming endocrinology from laborious bioassays to quantitative science and of course these assays related to the ovary. From there I went to Baylor College of Medicine, a mecca of molecular biology, cloning genes and generating mouse models. It has been a fascinating and joyous journey.

Modelling Epithelial Ovarian Cancer in Mice: Classical and Emerging Approaches

High-grade serous epithelial ovarian cancer (HGSC) is the most aggressive subtype of epithelial ovarian cancer. The identification of germline and somatic mutations along with genomic information unveiled by The Cancer Genome Atlas (TCGA) and other studies has laid the foundation for establishing preclinical models with high fidelity to the molecular features of HGSC. Notwithstanding such progress, the field of HGSC research still lacks a model that is both robust and widely accessible. In this review, we discuss the recent advancements and utility of HGSC genetically engineered mouse models (GEMMs) to date. Further analysis and critique on alternative approaches to modelling HGSC considers technological advancements in somatic gene editing and modelling prototypic organs, capable of tumorigenesis, on a chip.

Ovarian BDNF promotes survival, migration, and attachment of tumor precursors originated from p53 mutant fallopian tube epithelial cells

High-grade serous ovarian carcinoma (HGSOC) is the most lethal gynecological malignancy. New evidence supports a hypothesis that HGSOC can originate from fallopian tube epithelium (FTE). It is unclear how genetic alterations and pathophysiological processes drive the progression of FTE tumor precursors into widespread HGSOCs. In this study, we uncovered that brain-derived neurotrophic factor (BDNF) in the follicular fluid stimulates the tropomyosin receptor kinase B (TrkB)-expressing FTE cells to promote their survival, migration, and attachment. Using in vitro and in vivo models, we further identified that the acquisition of common TP53 gain-of-function (GOF) mutations in FTE cells led to enhanced BDNF/TrkB signaling compared to that of FTE cells with TP53 loss-of-function (LOF) mutations. Different mutant p53 proteins can either increase TrkB transcription or enhance TrkB endocytic recycling. Our findings have demonstrated possible interplays between genetic alterations in FTE tumor precursors (i.e., p53 GOF mutations) and pathophysiological processes (i.e., the release of follicular fluid upon ovulation) during the initiation of HGSOC from the fallopian tube. Our data revealed molecular events underlying the link between HGSOC tumorigenesis and ovulation, a physiological process that has been associated with risk factors of HGSOC.

Ubiquitin ligase TRIM71 suppresses ovarian tumorigenesis by degrading mutant p53

Hotspot p53 mutants augment cancer cell proliferation, metastasis and metabolism through their gain-of-function (GOF). Ovarian cancer sustains the highest frequency of TP53 mutations, but the mechanisms underlying regulation of mutant p53s’ GOF in this type of cancer remain incompletely understood. Herein, we identified the E3-ubiquitin ligase TRIM71 as a novel mutant p53-binding protein. Ectopic TRIM71-induced ubiquitination and proteasomal degradation of mutant p53 by binding to its transactivation (TA) domain, and inhibited the expression of a broad spectrum of mutant p53 target genes. Ectopic TRIM71 also restrained, whereas ablation of TRIM71 endorsed, ovarian carcinoma cell growth in vitro and in vivo. Significantly, TRIM71 overexpression is highly associated with favorable prognosis, particularly, in TP53-mutated ovarian carcinomas. Altogether, our findings unveil the anti-tumor function of TRIM71 in ovarian cancer development and prognosis by downregulating mutant p53s.

Characteristics of in Vivo Model Systems for Ovarian Cancer Studies

An understanding of the molecular pathogenesis and heterogeneity of ovarian cancer holds promise for the development of early detection strategies and novel, efficient therapies. In this review, we discuss the advantages and limitations of animal models available for basic and preclinical studies. The fruit fly model is suitable mainly for basic research on cellular migration, invasiveness, adhesion, and the epithelial-to-mesenchymal transition. Higher-animal models allow to recapitulate the architecture and microenvironment of the tumor. We discuss a syngeneic mice model and the patient derived xenograft model (PDX), both useful for preclinical studies. Conditional knock-in and knock-out methodology allows to manipulate selected genes at a given time and in a certain tissue. Such models have built our knowledge about tumor-initiating genetic events and cell-of-origin of ovarian cancers; it has been shown that high-grade serous ovarian cancer may be initiated in both the ovarian surface and tubal epithelium. It is postulated that clawed frog models could be developed, enabling studies on tumor immunity and anticancer immune response. In laying hen, ovarian cancer develops spontaneously, which provides the opportunity to study the genetic, biochemical, and environmental risk factors, as well as tumor initiation, progression, and histological origin; this model can also be used for drug testing. The chick embryo chorioallantoic membrane is another attractive model and allows the study of drug response.

LINC01127 promotes the development of ovarian tumors by regulating the cell cycle

BACKGROUND

Ovarian cancer is characterized by the high mortality rate and poor prognosis. Nevertheless, the oncogenesis mechanisms of ovarian cancer remain unclear. In our study, we focused on the potential role of lncRNA LINC01127 in the pathogenesis of ovarian cancer and its underlying mechanism.

METHODS

LINC01127, which may participate in the development of ovarian cancer, was screened out by bioinformatics analysis. GSEA was used to analyze the function of LINC01127. QRT-PCR was used to analyze the LINC01127 level in 72 cases of ovarian cancer tissues and 53 cases of normal ovarian tissues. LINC01127 level in ovarian cancer cell lines was also determined by qRT-PCR. Subsequently, the selected ovarian tumor cells were transfected with LINC01127 siRNA by Lipofectamine 2000, followed by cell cycle detection using flow cytometry. The regulatory effects of LINC01127 on tumor growth and cell cycle in nude mice were verified by tumor formation assay. The mechanism of LINC01127 involving in cell cycle regulation was further explored by Western Blot.

RESULTS

LINC01127 expression in ovarian cancer tissues was significantly higher than that in normal ovary tissues. The expression level of LINC01127 was negatively correlated with the prognosis of patients with ovarian cancer. GSEA analysis showed that LINC01127 was mainly enriched in the regulation of cell cycle. After transfection with LINC01127 siRNA, the proliferative abilities of SKOV3 and HO8910 cells were inhibited and cell cycle was arrested at G1/G0 phase. Tumorigenicity assay in nude mice showed that low expression of LINC01127 inhibited the growth of ovarian tumors. Further study found that LINC01127 knockdown upregulated expression levels of Cyclin D, Cyclin E and CDK4, but dramatically upregulated expression levels of P16 and P21. Meanwhile, the AKT and ERK pathways were inhibited by LINC01127 knockdown.

CONCLUSIONS

LINC01127 was up-regulated in ovarian cancer tissues. LINC01127 may be involved in the development of ovarian cancer by accelerating cell cycle progression through promoting the phosphorylation of ERK and AKT.

Cell Origins of High-Grade Serous Ovarian Cancer

High-grade serous ovarian cancer, also known as high-grade serous carcinoma (HGSC), is the most common and deadliest type of ovarian cancer. HGSC appears to arise from the ovary, fallopian tube, or peritoneum. As most HGSC cases present with widespread peritoneal metastases, it is often not clear where HGSC truly originates. Traditionally, the ovarian surface epithelium (OSE) was long believed to be the origin of HGSC. Since the late 1990s, the fallopian tube epithelium has emerged as a potential primary origin of HGSC. Particularly, serous tubal intraepithelial carcinoma (STIC), a noninvasive tumor lesion formed preferentially in the distal fallopian tube epithelium, was proposed as a precursor for HGSC. It was hypothesized that STIC lesions would progress, over time, to malignant and metastatic HGSC, arising from the fallopian tube or after implanting on the ovary or peritoneum. Many clinical studies and several mouse models support the fallopian tube STIC origin of HGSC. Current evidence indicates that STIC may serve as a precursor for HGSC in high-risk women carrying germline BRCA1 or 2 mutations. Yet not all STIC lesions appear to progress to clinical HGSCs, nor would all HGSCs arise from STIC lesions, even in high-risk women. Moreover, the clinical importance of STIC remains less clear in women in the general population, in which 85–90% of all HGSCs arise. Recently, increasing attention has been brought to the possibility that many potential precursor or premalignant lesions, though composed of microscopically—and genetically—cancerous cells, do not advance to malignant tumors or lethal malignancies. Hence, rigorous causal evidence would be crucial to establish that STIC is a bona fide premalignant lesion for metastatic HGSC. While not all STICs may transform into malignant tumors, these lesions are clearly associated with increased risk for HGSC. Identification of the molecular characteristics of STICs that predict their malignant potential and clinical behavior would bolster the clinical importance of STIC. Also, as STIC lesions alone cannot account for all HGSCs, other potential cellular origins of HGSC need to be investigated. The fallopian tube stroma in mice, for instance, has been shown to be capable of giving rise to metastatic HGSC, which faithfully recapitulates the clinical behavior and molecular aspect of human HGSC. Elucidating the precise cell(s) of origin of HGSC will be critical for improving the early detection and prevention of ovarian cancer, ultimately reducing ovarian cancer mortality.

From Follicular Development and Ovulation to Ovarian Cancers: An Unexpected Journey

Follicular development and ovulation are complex development processes that are regulated by multiple, interacting pathways and cell types. The oocyte, cumulus cells, granulosa cells, and theca cells communicate to impact follicular development and ovulation. Many hormones and cytokines control intracellular regulatory networks and transcription factors, some of which are cell type specific. Molecular biology approaches and mutant mouse models have contributed immensely to our knowledge of what genes and signaling cascades impact each stage of follicular development and ovulation, and how the alteration of gene expression profiles and the activation of specific signaling pathways can impact ovarian cancer development in ovarian surface epithelial cells as well as granulosa cells. This chapter explores how pathways controlling normal follicle development and ovulation can be diverted to abnormal development.

Autophagy as an emerging therapy target for ovarian carcinoma

Autophagy is a conserved cellular self-digestion pathway for maintenance of homeostasis under basal and stressed conditions. Autophagy plays pivotal roles in the pathogenesis of many diseases, such as aging-related diseases, autoimmune diseases, cardiovascular diseases, and cancers. Of special note is that accumulating data suggest an intimate relationship between autophagy and ovarian carcinoma. Autophagy is well identified to act as either as a tumor-suppressor or as a tumor-promoter in ovarian carcinoma. The exact function of autophagy in ovarian carcinoma is highly dependent on the circumstances of cancer including hypoxic, nutrient-deficient, chemotherapy and so on. However, the mechanism underlying autophagy associated with ovarian carcinoma remains elusive, the precise role of autophagy in ovarian carcinoma also remains undetermined. In this review, we tried to sum up and discuss recent research achievements of autophagy in ovarian cancer. Moreover, waves of novel therapies ways for ovarian carcinoma based on the functions of autophagy were collected.

Quinacrine upregulates p21/p27 independent of p53 through autophagy-mediated downregulation of p62-Skp2 axis in ovarian cancer

We have previously shown that the anti-malarial compound Quinacrine (QC) inhibits ovarian cancer (OC) growth by modulating autophagy. In the present study we extended these studies to identify the molecular pathways regulated by QC to promote apoptosis independent of p53 status in OC. QC exhibited strong anti-cancer properties in OC cell lines in contrast to other anti-malarial autophagy inhibiting drugs. QC treatment selectively upregulated cell cycle inhibitor p21, and downregulated F box protein Skp2 and p62/SQSTM1 expression independent of p53 status. Genetic downregulation of key autophagy protein ATG5 abolished QC-mediated effects on both cell cycle protein p21/Skp2 as well as autophagic cargo protein p62. Furthermore, genetic silencing of p62/SQSTM1 resulted in increased sensitivity to QC-mediated apoptosis, downregulated Skp2 mRNA and increased accumulation of p21 expression. Likewise, genetic knockdown of Skp2 resulted in the upregulation of p21 and p27 and increased sensitivity of OC cells to QC treatment. In contrast, transient overexpression of exogenous p62-HA plasmid rescued the QC-mediated Skp2 downregulation indicating the positive regulation of Skp2 by p62. Collectively, these data indicate that QC-mediated effects on cell cycle proteins p21/Skp2is autophagy-dependent and p53-independent in high grade serious OC cells.

Mutant p53 stimulates cell invasion through an interaction with Rad21 in human ovarian cancer cells

Missense mutations of TP53 are extremely common, and mutant p53 accumulation and gain-of-function play crucial roles in human ovarian cancer. Here, we investigated the role of mutant p53 in cell migration and invasion as well as its underlying molecular mechanisms in human ovarian cancer cells. Overexpression of mutant p53 significantly increased migration and invasion in p53-null SKOV3 cells. In contrast, knockdown of mutant p53 significantly compromised mutant p53-induced cell migration and invasion. Microarray analysis revealed that several migration/invasion-related genes, including S1PR1 (Sphingosine-1-phosphate receptor 1) and THBS1 (Thrombospodin 1), were significantly upregulated in SKOV3 cells that overexpressed mutant p53-R248 (SKOV3^R248). We found that Rad21 is involved in the transcriptional regulation of the migration/invasion-related genes induced by mutant p53-R248. Knockdown of Rad21 significantly attenuated the mutant p53-R248-induced invasion and the expressions of S1PR1 and THBS1. Moreover, co-immunoprecipitation and chromatin immunoprecipitation assays revealed that mutant p53 interacts with Rad21 and binds to the Rad21-binding elements in the S1PR1 and THBS1 genes. Finally, downregulation of S1PR1 significantly attenuated the invasion driven by mutant p53-R248. These novel findings reveal that mutant p53-R248 maintains gain-of-function activity to stimulate cell invasion and induces the related gene expressions through an interaction with Rad21 in human ovarian cancer cells.

Mass spectrometric profiling reveals association of N-glycan patterns with epithelial ovarian cancer progression

Aberrant changes of N-glycan modifications on proteins have been linked to various diseases including different cancers, suggesting possible avenue for exploring their etiologies based on N-glycomic analysis. Changes in N-glycan patterns during epithelial ovarian cancer development have so far been investigated mainly using serum, plasma, ascites, and cell lines. However, changes in patterns of N-glycans in tumor tissues during epithelial ovarian cancer progression have remained largely undefined. To investigate whether changes in N-glycan patterns correlate with oncogenesis and progression of epithelial ovarian cancer, we profiled N-glycans from formalin-fixed paraffin-embedded tissue slides using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and quantitatively compared among different pathological grades of epithelial ovarian cancer and healthy controls. Our results show that among the 80 compositions of N-glycan detected, expression levels of high-mannose type were higher in epithelial ovarian cancer samples than that observed in healthy controls, accompanied by reduced levels of hybrid-type glycans. By applying receiver operating characteristic analysis, we show that a combined panel composed of four high-mannose and three fucosylated neutral complex N-glycans allows for good discrimination of epithelial ovarian cancer from healthy controls. Furthermore, using a statistical analysis of variance assay, we found that different N-glycan patterns, including 2 high-mannose-type, 2 fucosylated and sialylated complex structures, and 10 fucosylated neutral complex N-glycans, exhibited specific changes in N-glycan abundance across epithelial ovarian cancer grades. Together, our results provide strong evidence that N-glycomic changes are a strong indicator for epithelial ovarian cancer pathological grades and should provide avenues to identify novel biomarkers for epithelial ovarian cancer diagnosis and monitoring.

Novel siRNA formulation to effectively knockdown mutant p53 in osteosarcoma

Objectives

The tumor suppressor p53 plays a crucial role in the development of osteosarcoma. The primary objective of this study is to develop and optimize lipid based nanoparticle formulations that can carry siRNA and effectively silence mutant p53 in 318–1, a murine osteosarcoma cell line.

Methods

The nanoparticles were composed of a mixture of two lipids (cholesterol and DOTAP) and either PLGA or PLGA-PEG and prepared by using an EmulsiFlex-B3 high pressure homogenizer. A series of studies that include using different nanoparticles, different amount of siRNAs, cell numbers, incubation time, transfection media volume, and storage temperature was performed to optimize the gene silencing efficiency.

Key findings

Replacement of lipids by PLGA or PLGA-PEG decreased the particle size and overall cytotoxicity. Among all lipid-polymer nanoformulations, nanoparticles with 10% PLGA showed highest mutant p53 knockdown efficiency while maintaining higher cell viability when a nanoparticle to siRNA ratio equal to 6.8:0.66 and 75 nM siRNA was used. With long term storage the mutant p53 knockdown efficiency decreased to a greater extent.

Conclusions

This study warrants a future evaluation of this formulation for gene silencing efficiency of mutant p53 in tissue culture and animal models for the treatment of osteosarcoma.

p53 and its mutants on the slippery road from stemness to carcinogenesis

Normal development, tissue homeostasis and regeneration following injury rely on the proper functions of wide repertoire of stem cells (SCs) persisting during embryonic period and throughout the adult life. Therefore, SCs employ robust mechanisms to preserve their genomic integrity and avoid heritage of mutations to their daughter cells. Importantly, propagation of SCs with faulty DNA as well as dedifferentiation of genomically altered somatic cells may result in derivation of cancer SCs, which are considered to be the driving force of the tumorigenic process. Multiple experimental evidence suggest that p53, the central tumor suppressor gene, plays a critical regulatory role in determination of SCs destiny, thereby eliminating damaged SCs from the general SC population. Notably, mutant p53 proteins do not only lose the tumor suppressive function, but rather gain new oncogenic function that markedly promotes various aspects of carcinogenesis. In this review, we elaborate on the role of wild type and mutant p53 proteins in the various SCs types that appear under homeostatic conditions as well as in cancer. It is plausible that the growing understanding of the mechanisms underlying cancer SC phenotype and p53 malfunction will allow future optimization of cancer therapeutics in the context of precision medicine.

TP53 mutation-mediated genomic instability induces the evolution of chemoresistance and recurrence in epithelial ovarian cancer

BACKGROUND

Genomic instability caused by mutation of the checkpoint molecule TP53 may endow cancer cells with the ability to undergo genomic evolution to survive stress and treatment. We attempted to gain insight into the potential contribution of ovarian cancer genomic instability resulted from TP53 mutation to the aberrant expression of multidrug resistance gene MDR1.

METHODS

TP53 mutation status was assessed by performing nucleotide sequencing and immunohistochemistry. Ovarian cancer cell DNA ploidy was determined using Feulgen-stained smears or flow cytometry. DNA copy number was analyzed by performing fluorescence in situ hybridization (FISH).

RESULTS

In addition to performing nucleotide sequencing for 5 cases of ovarian cancer, TP53 mutations were analyzed via immunohistochemical staining for P53. Both intensive P53 immunohistochemical staining and complete absence of signal were associated with the occurrence of TP53 mutations. HE staining and the quantification of DNA content indicated a significantly higher proportion of polyploidy and aneuploidy cells in the TP53 mutant group than in the wild-type group (p < 0.05). Moreover, in 161 epithelial ovarian cancer patients, multivariate logistic analysis identified late FIGO (International Federation of Gynecology and Obstetrics) stage, serous histotype, G3 grade and TP53 mutation as independent risk factors for ovarian cancer recurrence. In relapse patients, the proportion of chemoresistant cases in the TP53 wild-type group was significantly lower than in the mutant group (63.6% vs. 91.8%, p < 0.05). FISH results revealed a higher percentage of cells with >6 MDR1 copies and chromosome 7 amplication in the TP53 mutant group than in the wild-type group [11.7 ± 2.3% vs. 3.0 ± 0.7% and 2.1 ± 0.7% vs. 0.3 ± 0.05%, (p < 0.05), respectively]. And we observed a specific increase of MDR1 and chromosome 7 copy numbers in the TP53 mutant group upon disease regression (p < 0.01).

CONCLUSIONS

TP53 mutation-associated genomic instability may promote chromosome 7 accumulation and MDR1 amplification during ovarian cancer chemoresistance and recurrence. Our findings lay the foundation for the development of promising chemotherapeutic approaches to treat aggressive and recurrent ovarian cancer.

Emerging Non-Canonical Functions and Regulation by p53: p53 and Stemness

Since its discovery nearly 40 years ago, p53 has ascended to the forefront of investigated genes and proteins across diverse research disciplines and is recognized most exclusively for its role in cancer as a tumor suppressor. Levine and Oren (2009) reviewed the evolution of p53 detailing the significant discoveries of each decade since its first report in 1979. In this review, we will highlight the emerging non-canonical functions and regulation of p53 in stem cells. We will focus on general themes shared among p53's functions in non-malignant stem cells and cancer stem-like cells (CSCs) and the influence of p53 on the microenvironment and CSC niche. We will also examine p53 gain of function (GOF) roles in stemness. Mutant p53 (mutp53) GOFs that lead to survival, drug resistance and colonization are reviewed in the context of the acquisition of advantageous transformation processes, such as differentiation and dedifferentiation, epithelial-to-mesenchymal transition (EMT) and stem cell senescence and quiescence. Finally, we will conclude with therapeutic strategies that restore wild-type p53 (wtp53) function in cancer and CSCs, including RING finger E3 ligases and CSC maintenance. The mechanisms by which wtp53 and mutp53 influence stemness in non-malignant stem cells and CSCs or tumor-initiating cells (TICs) are poorly understood thus far. Further elucidation of p53's effects on stemness could lead to novel therapeutic strategies in cancer research.