The HNF-1β-USP28-Claspin pathway upregulates DNA damage-induced Chk1 activation in ovarian clear cell carcinoma

CLSPN actives Wnt/β-catenin signaling to facilitate glycolysis and cell proliferation in oral squamous cell carcinoma

OBJECTIVE

Oral squamous cell carcinoma (OSCC) is a common malignancy with a poor prognosis. This study aimed to determine the influence and underlying mechanisms of CLSPN on OSCC.

METHODS

CLSPN expression was tested using quantitative real-time polymerase chain reaction, immunohistochemistry, and western blotting. Flow cytometry, cell counting kit, and colony formation assays were performed to determine OSCC cell apoptosis, viability, and proliferation, respectively. In OSCC cells, the extracellular acidification rate (ECAR), oxygen consumption rate (OCR), glucose uptake, and lactate production were determined using the corresponding kits. Changes in the protein levels of HK2, PKM2, LDHA, Wnt3a, and β-catenin were assessed using western blotting.

RESULTS

CLSPN expression was increased in OSCC tissues. Overexpression of CLSPN in HSC-2 cells promoted cell proliferation, increased the levels of ECAR, glucose uptake, and lactate production, and increased the protein levels of HK2, PKM2, LDHA, Wnt3a, and β-catenin, but inhibited OCR levels and apoptosis. The knockdown of CLSPN in CAL27 cells resulted in the opposite results. Moreover, the effects of CLSPN overexpression on glycolysis and OSCC cell proliferation were reversed by Wnt3a knockdown. In vivo, knockdown of CLSPN restrained tumor growth, glycolysis, and the activation of Wnt/β-catenin signaling.

CONCLUSION

CLSPN promoted glycolysis and OSCC cell proliferation, and reduced apoptosis, which was achieved by the activation of Wnt/β-catenin signaling pathway.

The SUMOylation and ubiquitination crosstalk in cancer

BACKGROUND

The cancer occurrence and progression are largely affected by the post-translational modifications (PTMs) of proteins. Currently, it has been shown that the relationship between ubiquitination and SUMOylation is highly complex and interactive. SUMOylation affects the process of ubiquitination and degradation of substrates. Contrarily, SUMOylation-related proteins are also regulated by the ubiquitination process thus altering their protein levels or activity. Emerging evidence suggests that the abnormal regulation between this crosstalk may lead to tumorigenesis.

PURPOSE

In this review, we have discussed the study of the relationship between ubiquitination and SUMOylation, as well as the possibility of a corresponding application in tumor therapy.

METHODS

The relevant literatures from PubMed have been reviewed for this article.

CONCLUSION

The interaction between ubiquitination and SUMOylation is crucial for the occurrence and development of cancer. A greater understanding of the crosstalk of SUMOylation and ubiquitination may be more conducive to the development of more selective and effective SUMOylation inhibitors, as well as a promotion of synergy with other tumor treatment strategies.

Structure and function of the highly homologous deubiquitinases ubiquitin specific peptidase 25 and 28: Insights into their pathophysiological and therapeutic roles

Deubiquitination is the reverse process of ubiquitination, an important protein post-translational modification. Deubiquitination is assisted by deubiquitinating enzymes (DUBs), which catalyze the hydrolysis and removal of ubiquitin chains from targeted proteins and play an important role in regulating protein stability, cell signaling transduction, and programmed cell death. Ubiquitin-specific peptidases 25 and 28 (USP25 and USP28), important members of the USP subfamily of DUBs, are highly homologous, strictly regulated, and closely associated with various diseases, such as cancer and neurodegenerative diseases. Recently, the development of inhibitors targeting USP25 and USP28 for disease treatment has garnered extreme attention. Several non-selective and selective inhibitors have shown potential inhibitory effects. However, the specificity, potency, and action mechanism of these inhibitors remain to be further improved and clarified. Herein, we summarize the structure, regulation, emerging physiological roles, and target inhibition of USP25 and USP28 to provide a basis for the development of highly potent and specific inhibitors for the treatment of diseases, such as colorectal cancer, breast cancer and so on.

Clinicopathological characteristics, molecular features and novel diagnostic strategies for the detection of malignant transformation of endometriosis (Review)

Endometriosis is a benign gynecological disease that affects women of reproductive age. Although malignant transformation of endometriosis is rare, physicians must be aware of this due to the high incidence of clear cell carcinoma of the ovary (CCC) in Japan. The most prevalent histological subtype of ovarian cancer is CCC (~70%) followed by endometrioid carcinoma (30%). The present review discusses the clinicopathological and molecular features of endometriosis-associated ovarian cancer (EAOC) as well as prospects for novel diagnostic strategies. Papers published between 2000 and 2022 in the PubMed and Google Scholar databases were included. Contents of the endometriotic cyst fluid may be involved in carcinogenesis, although the underlying mechanisms are largely unknown. Some studies have proposed a possible mechanism wherein excessive hemoglobin, heme and iron could cause an imbalance in intracellular redox homeostasis in endometriotic cells. Combined with DNA damage and mutations, the imbalances may induce the development of EAOC. Endometriotic cells evolve to adapt to the prolonged unfavorable oxidative microenvironmental stress. On the other hand, macrophages enhance the antioxidative defense mechanism and protect endometriotic cells against oxidative damage through intercellular crosstalk and signaling pathways. Therefore, changes in redox signaling, energy metabolism and the tumor immune microenvironment could be the key elements in the malignant transformation of certain endometriotic cell clones. Additionally, non-invasive bioimaging (i.e., magnetic resonance relaxometry) and biomarkers (i.e., tissue factor pathway inhibitor 2) may be promising tools for early-stage detection of the disease. In conclusion, the present review summarizes the latest advancements in research on the biological characteristics and early diagnosis of malignant transformation of endometriosis.

Ubiquitin-specific protease 28: the decipherment of its dual roles in cancer development

As significant posttranslational modifications, ubiquitination and deubiquitination, whose balance is modulated by ubiquitin-conjugating enzymes and deubiquitinating enzymes (DUBs), can regulate many biological processes, such as controlling cell cycle progression, signal transduction and transcriptional regulation. Belonging to DUBs, ubiquitin-specific protease 28 (USP28) plays an essential role in turning over ubiquitination and then contributing to the stabilization of quantities of substrates, including several cancer-related proteins. In previous studies, USP28 has been demonstrated to participate in the progression of various cancers. Nevertheless, several reports have recently shown that in addition to promoting cancers, USP28 can also play an oncostatic role in some cancers. In this review, we summarize the correlation between USP28 and tumor behaviors. We initially give a brief introduction of the structure and related biological functions of USP28, and we then introduce some concrete substrates of USP28 and the underlying molecular mechanisms. In addition, the regulation of the actions and expression of USP28 is also discussed. Moreover, we concentrate on the impacts of USP28 on diverse hallmarks of cancer and discuss whether USP28 can accelerate or inhibit tumor progression. Furthermore, clinical relevance, including impacting clinical prognosis, influencing therapy resistance and being the therapy target in some cancers, is depicted systematically. Thus, assistance may be given to future experimental designs by the information provided here, and the potential of targeting USP28 for cancer therapy is emphasized.

USP28 enables oncogenic transformation of respiratory cells and its inhibition potentiates molecular therapy targeting mutant EGFR, BRAF and PI3K

Oncogenic transformation of lung epithelial cells is a multistep process, frequently starting with the inactivation of tumour suppressors and subsequent development of activating mutations in proto‐oncogenes, such as members of the PI3K or MAPK families. Cells undergoing transformation have to adjust to changes, including altered metabolic requirements. This is achieved, in part, by modulating the protein abundance of transcription factors. Here, we report that the ubiquitin carboxyl‐terminal hydrolase 28 (USP28) enables oncogenic reprogramming by regulating the protein abundance of proto‐oncogenes such as c‐JUN, c‐MYC, NOTCH and ∆NP63 at early stages of malignant transformation. USP28 levels are increased in cancer compared with in normal cells due to a feed‐forward loop, driven by increased amounts of oncogenic transcription factors such as c‐MYC and c‐JUN. Irrespective of oncogenic driver, interference with USP28 abundance or activity suppresses growth and survival of transformed lung cells. Furthermore, inhibition of USP28 via a small‐molecule inhibitor resets the proteome of transformed cells towards a ‘premalignant’ state, and its inhibition synergizes with clinically established compounds used to target EGFR^L858R‐, BRAF^V600E‐ or PI3K^H1047R‐driven tumour cells. Targeting USP28 protein abundance at an early stage via inhibition of its activity is therefore a feasible strategy for the treatment of early‐stage lung tumours, and the observed synergism with current standard‐of‐care inhibitors holds the potential for improved targeting of established tumours.

Clinicopathological significance of claspin overexpression and its efficacy as a novel biomarker for the diagnosis of urothelial carcinoma

We previously reported that claspin is a key regulator in the progression of gastric cancer and renal cell carcinoma. However, the clinicopathological significance of claspin in urothelial carcinoma (UC) has not been investigated. We analyzed the expression and distribution of claspin in UC cases by immunohistochemistry. In the non-neoplastic urothelium, the expression of claspin was either weak or absent, whereas UC tissues showed nuclear staining. The expression of claspin was detected in 58 (42%) of a total of 138 upper tract UC cases treated by radical nephroureterectomy without neoadjuvant chemotherapy. Claspin-positive UC cases were associated with nodular/flat morphology, variant histology, high tumor grade, high pathological T grade, and lymphatic and venous invasion. The expression of claspin was significantly associated with decreased progression-free survival and cancer-specific survival. In addition, claspin was co-expressed with Ki-67, PD-L1, HER2, EGFR, and p53 in consecutive tumor sections of UC. An immunohistochemical analysis of claspin in biopsy specimens revealed that strong to moderate claspin staining was more frequently observed in carcinoma in situ in comparison to dysplasia or the benign urothelium. Furthermore, immunocytochemistry for claspin on urine cytology slides demonstrated that the proportion of claspin-positive cells was significantly greater in high-grade UC than in benign cases. These results suggest that claspin may be a novel prognostic marker and a possible therapeutic target molecule for UC. Moreover, claspin could be a useful diagnostic biomarker of urothelial neoplasia.

Targeting DNA Damage Response Pathway in Ovarian Clear Cell Carcinoma

Ovarian clear cell carcinoma (OCCC) is one of the major types of ovarian cancer and is of higher relative prevalence in Asians. It also shows higher possibility of resistance to cisplatin-based chemotherapy leading to poor prognosis. This may be attributed to the relative lack of mutations and aberrations in homologous recombination-associated genes, which are crucial in DNA damage response (DDR), such as BRCA1, BRCA2, p53, RAD51, and genes in the Fanconi anemia pathway. On the other hand, OCCC is characterized by a number of genetic defects rendering it vulnerable to DDR-targeting therapy, which is emerging as a potent treatment strategy for various cancer types. Mutations of ARID1A, PIK3CA, PTEN, and catenin beta 1 (CTNNB1), as well as overexpression of transcription factor hepatocyte nuclear factor-1β (HNF-1β), and microsatellite instability are common in OCCC. Of particular note is the loss-of-function mutations in ARID1A, which is found in approximately 50% of OCCC. ARID1A is crucial for processing of DNA double-strand break (DSB) and for sustaining DNA damage signaling, rendering ARID1A-deficient cells prone to impaired DNA damage checkpoint regulation and hence sensitive to poly ADP ribose polymerase (PARP) inhibitors. However, while preclinical studies have demonstrated the possibility to exploit DDR deficiency in OCCC for therapeutic purpose, progress in clinical application is lagging. In this review, we will recapitulate the preclinical studies supporting the potential of DDR targeting in OCCC treatment, with emphasis on the role of ARID1A in DDR. Companion diagnostic tests (CDx) for predicting susceptibility to PARP inhibitors are rapidly being developed for solid tumors including ovarian cancers and may readily be applicable on OCCC. The potential of various available DDR-targeting drugs for treating OCCC by drawing analogies with other solid tumors sharing similar genetic characteristics with OCCC will also be discussed.

USP28: Oncogene or Tumor Suppressor? A Unifying Paradigm for Squamous Cell Carcinoma

Squamous cell carcinomas are therapeutically challenging tumor entities. Low response rates to radiotherapy and chemotherapy are commonly observed in squamous patients and, accordingly, the mortality rate is relatively high compared to other tumor entities. Recently, targeting USP28 has been emerged as a potential alternative to improve the therapeutic response and clinical outcomes of squamous patients. USP28 is a catalytically active deubiquitinase that governs a plethora of biological processes, including cellular proliferation, DNA damage repair, apoptosis and oncogenesis. In squamous cell carcinoma, USP28 is strongly expressed and stabilizes the essential squamous transcription factor ΔNp63, together with important oncogenic factors, such as NOTCH1, c-MYC and c-JUN. It is presumed that USP28 is an oncoprotein; however, recent data suggest that the deubiquitinase also has an antineoplastic effect regulating important tumor suppressor proteins, such as p53 and CHK2. In this review, we discuss: (1) The emerging role of USP28 in cancer. (2) The complexity and mutational landscape of squamous tumors. (3) The genetic alterations and cellular pathways that determine the function of USP28 in squamous cancer. (4) The development and current state of novel USP28 inhibitors.

Claspin Overexpression Promotes Tumor Progression and Predicts Poor Clinical Outcome in Prostate Cancer

Background: Claspin (CLSPN) expression is acknowledged as a poor clinical prognostic factor in various tumors. However, the clinical characteristics and biological functions of CLSPN in prostate cancer (PCa) are still to be clarified. The aim of our study was to evaluate the association of CLSPN expression during PCa progression and its potential role in prognosis. Methods: We analyzed mRNA expression of the CLSPN gene with various clinicopathological features using the Cancer Genome Atlas and GSE21032 dataset. Immunohistochemical assays were used to detect the protein expression levels of CLSPN in human PCa tissue microarrays. Furthermore, we characterized the role of CLSPN in PCa progression through in vitro experiments using a CLSPN knockout. Results: Immunohistochemistry and public datasets revealed that CLSPN expression was increased in PCa with: a high Gleason score; advanced pathological stage; and positive surgical margins. In addition, upregulation of CLSPN was correlated with shorter biochemical recurrence (BCR)-free survival and overall survival. After we knocked-out CLSPN in DU145 and LNCaP cells, the in vitro phenotypic results showed that the ability of the knockouts to proliferate, migrate, and invade was attenuated; but that apoptosis was promoted. Conclusions: Our data support an oncogenic role for CLSPN in PCa progression. Moreover, increased CLSPN expression was identified as an independent factor in predicting bCR-free survival and disease-free survival in PCa patients.

Overexpression of claspin promotes docetaxel resistance and is associated with prostate-specific antigen recurrence in prostate cancer

Although docetaxel (DTX) confers significant survival benefits in patients with castration‐resistant prostate cancer (CRPC), resistance to DTX inevitably occurs. Therefore, clarifying the mechanisms of DTX resistance may improve survival in patients with CRPC. Claspin plays a pivotal role in DNA replication stress and damage responses and is an essential regulator for the S‐phase checkpoint. CLSPN is an oncogenic gene that contributes to tumor proliferation in several human solid tumors. However, the clinical significance of claspin in prostate cancer (PCa) has not been examined. The present study aimed to elucidate the role of claspin and its relationship with DTX resistance in PCa. We immunohistochemically analyzed the expression of claspin in 89 PCa cases, of which 31 (35%) were positive for claspin. Claspin‐positive cases were associated with higher Gleason score, venous invasion, and perineural invasion. Kaplan–Meier analysis showed that high claspin expression was related to poor prostate‐specific antigen (PSA) relapse‐free prognosis. In a public database, high CLSPN expression was associated with poor PSA relapse‐free prognosis, Gleason score, T stage, lymph node metastasis, CRPC, and metastatic PCa. Claspin knockdown by siRNA decreased cell proliferation, upregulated DTX sensitivity, and suppressed the expression of Akt, Erk1/2, and CHK1 phosphorylation in DU145 and PC3 cell lines. Furthermore, claspin expression was much more upregulated in DTX‐resistant DU145 (DU145‐DR) than in parental DU145 cells. Claspin knockdown significantly upregulated the sensitivity to DTX in DU145‐DR cells. These results suggest that claspin plays an important role in PCa tumor progression and DTX resistance.

CCNE1 Is a Putative Therapeutic Target for ARID1A-Mutated Ovarian Clear Cell Carcinoma

Background: Ovarian clear cell carcinoma (OCCC) is resistant to platinum chemotherapy and is characterized by poor prognosis. Today, the use of poly (ADP-ribose) polymerase (PARP) inhibitor, which is based on synthetic lethality strategy and characterized by cancer selectivity, is widely used for new types of molecular-targeted treatment of relapsed platinum-sensitive ovarian cancer. However, it is less effective against OCCC. Methods: We conducted siRNA screening to identify synthetic lethal candidates for the ARID1A mutation; as a result, we identified Cyclin-E1 (CCNE1) as a potential target that affects cell viability. To further clarify the effects of CCNE1, human OCCC cell lines, namely TOV-21G and KOC7c (ARID1A mutant lines), and RMG-I and ES2 (ARID1A wild type lines) were transfected with siRNA targeting CCNE1 or a control vector. Results: Loss of CCNE1 reduced proliferation of the TOV-21G and KOC7c cells but not of the RMG-I and ES2 cells. Furthermore, in vivo interference of CCNE1 effectively inhibited tumor cell proliferation in a xenograft mouse model. Conclusion: This study showed for the first time that CCNE1 is a synthetic lethal target gene to ARID1A-mutated OCCC. Targeting this gene may represent a putative, novel, anticancer strategy in OCCC treatment.

A novel hemocompatible core@shell nanosystem for selective targeting and apoptosis induction in cancer cells

Synthesis, characterization and evaluation of transferrin-decorated mesoporous silica-coated silver nanoparticles as a novel hemocompatible core@shell nanosystem for selective targeting and apoptosis induction in cancer cells.

GSK-3β mediates the effects of HNF-1β overexpression in ovarian clear cell carcinoma

Deubiquitinase USP28 is a target gene of the transcription factor HNF1 homeobox β (HNF-1β), which promotes the survival of ovarian clear cell carcinoma (OCCC) cell lines. However, the pharmacological inhibition of HNF-1β can cause several adverse effects as it is abundantly expressed in numerous organ systems, including the kidney, liver, pancreas and digestive tract. Therefore, small interfering RNA (siRNA) screening was performed in the current study to identify other potential downstream targets of the HNF-1β-mediated pathway. The results revealed that glycogen synthase kinase-3β (GSK-3β) may be a potential downstream target affecting cell viability. To further clarify the effects of GSK-3β, two human OCCC cell lines, TOV-21G (HNF-1β overexpressing line) and ES2 (HNF-1β negative) were transfected with siRNA targeting GSK-3β or control vectors. Loss-of-function studies using RNAi-mediated gene silencing indicated that HNF-1β facilitated GSK-3β expression, resulting in the loss of phosphorylated nuclear factor-κB (p-NFκB) and the reduction of TOV-21G cell proliferation. The cell proliferation assay also revealed that GSK-3β inhibitors rescued the effects of HNF-1β silencing on cell viability in a dose-dependent manner. Furthermore, the GSK-3β inhibitor, AR-A014418, effectively inhibited tumor cell proliferation in a xenograft mouse model. In conclusion and to the best of our knowledge, the current study was the first to determine that GSK-3β is a target gene of HNF-1β. In addition, the results of the present study revealed the novel HNF-1β-GSK-3β-p-NFκB pathway, occurring in response to DNA damage. Targeting this pathway may therefore represent a putative, novel, anticancer strategy in patients with OCCC.

Claspin overexpression is associated with high-grade histology and poor prognosis in renal cell carcinoma

Renal cell carcinoma (RCC) is one of the most common human cancers. We previously reported that claspin is a key regulator in the progression of gastric cancer, and it likely plays an important role in cancer stem cells of gastric cancer. However, the significance of claspin in RCC has not been examined. First, we analyzed the expression and distribution of claspin in 95 RCC cases by immunohistochemistry. In the nonneoplastic kidney, the staining of claspin was either weak or absent, whereas RCC tissue showed nuclear staining. In total, claspin expression was detected in 45 (47%) of 95 RCC cases. The claspin staining appeared relatively stronger in high nuclear grade RCC than in low nuclear grade RCC. Claspin-positive RCC cases were associated with higher T grade, tumor stage, nuclear grade, vein invasion, and poorer prognosis. CLSPN siRNA treatment decreased RCC cell proliferation. The levels of phosphorylated Erk and Akt were lower in CLSPN siRNA-transfected RCC cells than in control cells. In addition, claspin was coexpressed with CD44, epidermal growth factor receptor, p53, and programmed death ligand-1. These results suggest that claspin plays an important role in tumor progression in RCC and might be a prognostic marker and novel therapeutic target molecule.

Deubiquitinase USP28 inhibits ubiquitin ligase KLHL2-mediated uridine-cytidine kinase 1 degradation and confers sensitivity to 5'-azacytidine-resistant human leukemia cells

Resistance to the chemotherapeutic drug 5'-azacytidine (5'-AZA) is a major obstacle in the treatment of patients with acute myeloid leukemia (AML). The uridine-cytidine kinase 1 (UCK1) has an established role in activating 5'-AZA and its protein level is significantly downregulated in patients resistant to the drug. However, the underlying molecular mechanism for the reduced UCK1 expression remains to be elucidated. Methods: Using mass spectrometry and molecular biochemistry analyses, we identified specific enzymes mediating UCK1 degradation. Human AML cell lines and murine AML model were used to characterize the effects of these enzymes on 5'-AZA resistance. Results: We demonstrated that the ubiquitin E3 ligase KLHL2 interacted with UCK1 and mediated its polyubiquitination at the K81 residue and degradation. We showed that deubiquitinase USP28 antagonized KLHL2-mediated polyubiquitylation of UCK1. We also provided evidence that ATM-mediated phosphorylation of USP28 resulted in its disassociation from KLHL2 and UCK1 destabilization. Conversely, UCK1 phosphorylation by 5'-AZA-activated ATM enhanced the KLHL2-UCK1 complex formation. Importantly, silencing KLHL2 or USP28 overexpression not only inhibited AML cell proliferation but also sensitized AML cells to 5'-AZA-induced apoptosis in vitro and in vivo. These results were no longer observed in USP28-deficient cells. Conclusions: Our study revealed a novel mechanism by which the KLHL2/USP28/ATM axis mediates resistance of AML cells to 5'-AZA by regulating UCK1 ubiquitination and phosphorylation. These results have direct clinical implications and provide a rationale for the combination drug treatment of AML patients.

Basal CHK1 activity safeguards its stability to maintain intrinsic S-phase checkpoint functions

The essential kinase CHK1 controls cell cycle checkpoint signaling and S-phase progression. Michelena et al. reveal that steady-state activity of CHK1 is required to sustain its own stability and that failure to do so results in CHK1 degradation and sensitizes cells to replication stress.

The DNA replication machinery frequently encounters impediments that slow replication fork progression and threaten timely and error-free replication. The CHK1 protein kinase is essential to deal with replication stress (RS) and ensure genome integrity and cell survival, yet how basal levels and activity of CHK1 are maintained under physiological, unstressed conditions is not well understood. Here, we reveal that CHK1 stability is controlled by its steady-state activity during unchallenged cell proliferation. This autoactivatory mechanism, which depends on ATR and its coactivator ETAA1 and is tightly associated with CHK1 autophosphorylation at S296, counters CHK1 ubiquitylation and proteasomal degradation, thereby preventing attenuation of S-phase checkpoint functions and a compromised capacity to respond to RS. Based on these findings, we propose that steady-state CHK1 activity safeguards its stability to maintain intrinsic checkpoint functions and ensure genome integrity and cell survival.

A diagnostic challenge of seromucinous borderline tumor: A case report

INTRODUCTION

Magnetic resonance (MR) relaxometry provides a noninvasive predictive tool to discriminate between benign ovarian endometrioma (OE) and endometriosis-associated ovarian cancer (EAOC). Transverse relaxation rate R2 value was determined using a single-voxel, multi-echo MR sequence (HISTO) by a 3T-MR system. R2 with cutoff value of 12.1 s was established to discriminate between benign and malignant tumors.

PATIENT CONCERNS

We present a case of a 39-year-old woman who was initially thought to be malignant transformation of endometriosis by diagnostic MR imaging of the vascularized solid components.

DIAGNOSIS

A R2 value of 42.62 s on MR relaxometry demonstrated that this case is non-malignant.

INTERVENTIONS

To confirm the diagnose, left salpingo-oophorectomy by laparoscopic surgery was performed.

OUTCOMES

Histopathological results revealed seromucinous borderline tumor (SMBT). Our experience suggests that preoperative MR relaxometry may be useful for discriminating "borderline (SMBT)" from "malignancy (EAOC)." Furthermore, immunohistochemical studies of this case demonstrated ovarian SMBT cells were positive for estrogen receptor, progesterone receptor, and hepatocyte nuclear factor-1beta. A similar expression pattern was also observed in patients with benign OE.

LESSONS

In many respects, SMBT characteristics differ from those of EAOC but resemble those of benign OE. MR relaxometry unveils a new clinical approach as an adjunctive modality for discriminating SMBT from EAOC.

Magnetic resonance imaging findings for discriminating clear cell carcinoma and endometrioid carcinoma of the ovary

Background

Common cancerous histological types associated with endometriosis are clear cell carcinoma (CCC) and endometrioid carcinoma (EC). CCC is regarded as an aggressive, chemoresistant histological subtype. Magnetic resonance imaging (MRI) offers some potential advantages to diagnose ovarian tumors compared with ultrasonography or computed tomography. This study aimed to identify MRI features that can be used to differentiate between CCC and EC.

Methods

We searched medical records of patients with ovarian cancers who underwent surgical treatment at Nara Medical University Hospital between January 2008 and September 2018; we identified 98 patients with CCC or EC who had undergone preoperative MRI. Contrasted MRI scans were performed less than 2 months before surgery. Patients were excluded from the study if they had no pathology, other pathological subtype of epithelial ovarian cancer, and/or salvage treatment for recurrence and metastatic ovarian cancer at the time of study initiation. Clinically relevant variables that were statistically significant by univariate analysis were selected for subsequent multivariate regression analysis to identify independent factors to distinguish CCC from EC.

Results

MRI of CCC and EC showed a large cystic heterogeneous mixed mass with mural nodules protruding into the cystic space. Univariate logistic regression analysis revealed that the growth pattern (broad-based nodular structures [multifocal/concentric sign] or polypoid structures [focal/eccentric sign]), surface irregularity (a smooth/regular surface or a rough/irregular/lobulated surface), “Width” of mural nodule, “Height-to-Width” ratio (HWR), and presence of preoperative ascites were factors that significantly differed between CCC and EC. In the multivariate logistic regression analysis, the growth pattern of the mural nodule (odds ratio [OR] = 0.69, 95% confidence interval [CI]: 0.013–0.273, p = 0.0004) and the HWR (OR = 3.71, 95% CI: 1.128–13.438, p = 0.036) were independent predictors to distinguish CCC from EC.

Conclusions

In conclusion, MRI data showed that the growth pattern of mural nodules and the HWR were independent factors that could allow differentiation between CCC and EC. This finding may be helpful to predict patient prognosis before operation.

Conceptual frameworks of synthetic lethality in clear cell carcinoma of the ovary

Targeting non-oncogenes may result in the selective death of cancer cells. Clear cell carcinoma of the ovary (CCC) may exhibit resistance against conventional chemotherapy and is associated with poor prognosis. The aim of the present report was to review synthetic lethality-based therapies for CCC. Previous English-language studies were reviewed to accumulate preclinical and clinical data on targeting synthetic lethal partners. Synthetic lethal interactions have a variety of types, involving components of a backup or parallel pathway with overlapping functions, components encoded by paralogous pairs, subunit components that form heteromeric complexes and components that are arranged in a single linear pathway. A set of candidate gene targets potentially resulting in synthetic lethality have been previously identified. HNF class homeobox, AT-rich interaction domain 1A, ATR serine/threonine kinase, ATM serine/threonine kinase, checkpoint kinase 1 and phosphatase and tensin homolog may be the key partner genes. A variety of loss of function genes in CCC are driver or passenger events and may function as synthetic lethal pairs under replication stress conditions. Further clinical studies will be required to investigate the safety and therapeutic effect of synthetic lethality pairs in CCC tumor types with replication stress.