Satoru Kyo

NAC1 Regulates PCK2 Expression and Activates Truncated Gluconeogenesis for Growth Advantage in Ovarian Cancer Cells

Nucleus accumbens-associated protein 1 (NAC1), a cancer-related transcriptional regulator, is overexpressed in several malignancies, including ovarian cancer. However, its role in ovarian carcinogenesis remains unclear. We aimed to investigate whether NAC1 contributes to metabolic adaptation in endometriosis-related ovarian neoplasms (ERONs) and elucidate its regulatory mechanisms. The clinical relationship between NAC1 and its potential downstream target, phosphoenolpyruvate carboxykinase isoform 2 (PCK2), was examined using immunohistochemical analysis of ovarian cancer specimens. A cell viability assay was performed to clarify the impact of PCK2 on ovarian cancer cell viability. Reporter and chromatin immunoprecipitation (ChIP) assays were conducted to evaluate transcriptional regulation by NAC1. Metabolomic profiling was performed to assess the functional impact of the NAC1–PCK2 axis. A positive correlation between NAC1 and PCK2 expression was observed, and co-expression was associated with poor long-term survival. Knockdown of PCK2 led to a significant reduction in cell viability, indicating that PCK2 is required for maintaining cell survival. Reporter and ChIP assays confirmed that NAC1 directly binds to the PCK2 promoter via the CATG motif. The metabolomic analysis demonstrated that NAC1 promotes truncated gluconeogenesis and de novo serine synthesis through PCK2 upregulation. These findings suggest that NAC1 contributes to ovarian cancer progression by promoting metabolic adaptation, highlighting the NAC1–PCK2 axis as a potential therapeutic target for ERONs.

NAC1/ACOX2 Axis as a Novel Therapeutic Target for Endometriosis-Related Ovarian Neoplasms

NAC1, a transcription regulator protein associated with cancer, is highly expressed in several tumor types, including ovarian cancer. However, it remains unclear how NAC1 is involved in carcinogenesis. Our previous studies demonstrated that the knockdown of NAC1 in ovarian clear cell carcinoma (OCCC) cell lines induces apoptosis and restores their sensitivity to chemotherapy, suggesting NAC1 as a potential therapeutic target. The present study aimed to identify molecular pathways through which NAC1 is involved in the development of endometriosis-related ovarian neoplasms (ERONs). Immunohistochemistry was performed to clarify the relationship between NAC1 and the potential target protein ACOX2 in surgical specimens of ERONs. Reporter assays were conducted to determine the interaction of NAC1 with the specific cis-element on the ACOX2 promoter. Subsequently, a ChIP assay was performed to investigate the in vivo interaction of NAC1 with the ACOX2 promoter. There was an inverse relationship between NAC1 and ACOX2 expressions in the tumor specimens of ERONs. High NAC1/low ACOX2 expression was found to be a worse prognostic marker for patient survival. Reporter assays demonstrated that NAC1 negatively regulated the ACOX2 promoter via the proximal CATG site. ChIP assays confirmed in vivo binding of NAC1 to the promoter. The present study implicated that NAC1 may contribute to the development of ERONs as a transcriptional repressor by regulating ACOX2 expression via specific binding sites on the promoter, providing a novel insight into the NAC1/ACOX2 axis as a potential therapeutic target of this tumor type.

Exploring the Genetic and Clinical Landscape of Dedifferentiated Endometrioid Carcinoma

Dedifferentiated endometrioid carcinoma (DDEC) is rare, has a poor prognosis, and the genes responsible for dedifferentiation remain unclear. This study aimed to clarify the characteristics of DDEC in Japanese patients and develop treatment strategies. Eighteen DDEC cases were included; their clinicopathological features and prognoses were analyzed and compared to those of other histological subtypes. The samples were divided into well-differentiated and undifferentiated components; immunostaining and whole-exome sequencing (n = 3 cases) were conducted. The incidence of DDEC was 2.0% among endometrial cancers. The 5-year progression-free survival and the 5-year overall survival for DDEC was approximately 40% and 30%, respectively. Immunohistochemistry showed that 66.7% of patients were mismatch repair deficient. The rate of p53 mutations was higher than that reported in previous studies, and patients with p53 mutations in the undifferentiated components had a poor prognosis. Whole-exome sequencing revealed different gene mutations and mutation signatures between well-differentiated and undifferentiated components. New genetic mutations in undifferentiated regions were uncommon in all three cases. One case (case 1) exhibited homologous recombination deficiency, whereas the other two showed microsatellite instability-high and hypermutator phenotypes. Genetic analysis suggests that immune checkpoint and poly (ADP-ribose) polymerase inhibitors and drugs targeting the p53 pathway may be effective against DDEC.

Frequent PIK3CA mutation in normal endometrial gland drives spheroid formation and may be involved in stem cell propagation

AbstractRecent studies reported the presence of oncogenic mutations in normal endometrial glands, but the biological significance remains unclear. The present study investigated the status of KRAS/PIK3CA driver mutations in normal endometrial glands as well as spheroids derived from single glands. The normal endometria of surgically removed uteri (n = 3) were divided into nine regions, and 40 endometrial single glands were isolated from each region. The DNAs of 10 glands in each region were extracted and subjected to Sanger sequencing for KRAS or PIK3CA driver mutations, while the remaining 30 glands were conferred to a long‐term spheroid culture, followed by Sanger sequencing. Immunohistochemical analyses of stem cell (Axin2, ALDH1A1, SOX9) markers were undertaken for spheroids. Sanger sequencing successfully detected oncogenic mutations of KRAS or PIK3CA in a single gland. Twenty‐five of the 270 glands (9.3%) had mutations in either KRAS or PIK3CA, and the mutation frequency in each endometrial region varied from 0% to 50%. The droplet digital PCR showed high mutation allele frequency (MAF) of PIK3CA mutation, suggestive of clonal expansion of mutated cells within a gland. Over 60% of the collected spheroids had PIK3CA mutations, but no KRAS mutations were detected. Immunohistochemically, spheroids were mainly composed of cells with stem cell marker expressions. High MAF of PIK3CA mutation in a single gland as well as frequent PIK3CA mutation in stem cell‐rich spheroids that originated from a single gland suggest the role of PIK3CA mutation in stem cell propagation. This information could improve our understanding of endometrial physiology as well as stem cell‐oriented endometrial regeneration and carcinogenesis.

The fallopian tube as origin of ovarian cancer: Change of diagnostic and preventive strategies

AbstractOvarian cancer is the leading cause of gynecologic cancer death in the world, and its prevention and early diagnosis remain the key to its treatment, especially for high‐grade serous carcinoma (HGSC). Accumulating epidemiological and molecular evidence has shown that HGSC originates from fallopian tube secretory cells through serous tubal intraepithelial carcinoma. Comprehensive molecular analyses and mouse studies have uncovered the key driver events for serous carcinogenesis, providing novel molecular targets. Risk‐reducing bilateral salpingo‐oophorectomy (RRSO) has been proposed to reduce the subsequent occurrence of serous carcinoma in high‐risk patients with BRCA mutations. However, there is no management strategy for isolated precursors detected at RRSO, and the role of subsequent surgery or chemotherapy in preventing serous carcinoma remains unclear. Surgical menopause due to RRSO provides a variety of problems related to patients’ quality of life, and the risks and benefits of hormone replacement are under investigation, especially for women without a previous history of breast cancer. An additional surgical option, salpingectomy with delayed oophorectomy, has been proposed to prevent surgical menopause. The number of opportunistic salpingectomies at the time of surgery for benign disease to prevent the future occurrence of HGSC has increased worldwide. Thus, the changing concept of the origin of serous carcinoma has provided us a great opportunity to develop novel diagnostic and therapeutic approaches.

Integrated Molecular and Functional Characterization of Cervical Small-Cell Neuroendocrine Carcinoma Using a 3D Organoid Model

Cervical small-cell neuroendocrine carcinoma (SCNEC) is a rare cervical cancer with high metastatic potential and is frequently associated with high-risk human papillomavirus (HPV) infection. Because of its low incidence, SCNEC remains understudied and treatment options are limited, posing major therapeutic challenges. This study aimed to characterize SCNEC at the molecular and functional levels to support more informed therapeutic strategies. Organoids and spheroids were generated from a cervical SCNEC biopsy, and a matched organoid-derived xenograft was established in immunodeficient mice. Model fidelity was evaluated by histopathology and immunohistochemistry. HPV status was assessed by p16 immunostaining and HPV18 PCR, and viral–host integration sites were inferred using whole-exome sequencing (WES) junction reads. WES was also used to compare shared somatic variants and copy-number alterations across the patient tumor, organoid, and xenograft. Drug responses were assessed in organoids and spheroids following exposure to a panel of chemotherapeutic agents and a targeted inhibitor. Organoids exhibited robust growth, morphologic maturation, and efficient recovery after cryopreservation. The organoids and matched xenografts faithfully recapitulated SCNEC, with preserved neuroendocrine differentiation (CD56, synaptophysin, and NSE positivity), a high Ki-67 proliferative index (>80%), and strong p16 expression. HPV18 status was conserved across the primary tumor, organoids, and xenografts, with an integration site at chr8 (8q24.21) associated with increased MYC expression. WES revealed strong cross-model concordance, including 26 shared somatic variants with a canonical PIK3CA hotspot mutation (p.E542K) and conserved oncogenic copy-number gains of PIK3CA, TERT, and MYC, as well as copy number loss of TP53. Functional assays showed dose-dependent loss of viability following exposure to conventional cytotoxic agents or an mTOR pathway inhibitor. This study presents the first integrated molecular and functional analyses of patient tumors and matched organoid and xenograft models in cervical SCNEC. These models offer robust resources for mechanistic studies and may enable precision therapeutic strategies for this rare malignancy.

A Comparative Analysis of Usual- and Gastric-Type Cervical Adenocarcinoma in a Japanese Population Reveals Distinct Clinicopathological and Molecular Features with Prognostic and Therapeutic Insights

Gastric-type cervical adenocarcinoma (GCA) is a rare and aggressive subtype of cervical adenocarcinoma. Despite its clinical significance, its molecular carcinogenesis and therapeutic targets remain poorly understood. This study aimed to compare the clinicopathological, immunohistochemical, and molecular profiles of GCA and usual-type cervical adenocarcinoma (UCA), exploring prognostic and therapeutic biomarkers in a Japanese population. A total of 110 cervical adenocarcinoma cases, including 16 GCA and 94 UCA cases, were retrospectively analyzed for clinicopathological features, and a panel of immunohistochemical markers was assessed. Sanger sequences were performed for the KRAS, PIK3CA, and BRAF genes, and survival and clinicopathological correlations were assessed using Kaplan–Meier and Cox regression analyses. GCA was significantly associated with more aggressive features than UCA, including lymph node involvement, advanced FIGO stages, increasing recurrence rate, and poor survival status. High ARID1B expression was observed in a subset of GCA cases and correlated with worse progression-free and overall survival. Additionally, PD-L1 expression was more frequent in GCA than UCA and was associated with unfavorable prognostic factors. Conversely, UCA cases showed strong p16 expression, supporting their HPV-driven pathogenesis. Molecular profiling revealed KRAS and PIK3CA mutations in both subtypes, while BRAF mutations were identified exclusively in GCA. These findings reveal distinct clinical and molecular profiles for both tumor types and underscore ARID1B and PD-L1 as predictive prognostic and therapeutic biomarkers in GCA, implicating the use of subtype-specific treatment strategies.

Histological and Genetic Diversity in Ovarian Mucinous Carcinomas: A Pilot Study

Tumor heterogeneity remains an ongoing challenge in the field of cancer therapy. Intratumor heterogeneity significantly complicates the diagnosis of cancer and presents challenging clinical problems due to resistance to drug therapy. This study aimed to elucidate the genetic changes histologically (mucinous cystadenoma (MCA), mucinous borderline tumor (MBT), and mucinous ovarian carcinoma (MOC)) in a portion of mucinous ovarian tumors within the same sample. Seven tumor samples obtained from different patients were used to evaluate the genetic mutations in each component. Intratumor genetic heterogeneity was observed in all patients; among them, BRAF (V600E) and p53 (T118I, P142S, T150I, and T170M) point mutations were observed in the MBT component, while KRAS (G12D and G13D) and PIK3CA (E545K) mutations were found in the MOC component. The current findings suggest that diverse genetic alterations occur in mucinous tumors, according to tumor histology. Tumor heterogeneity and genetic diversity in mucinous ovarian tumors might be the cause of treatment failure. Knowledge of intertumor heterogeneity may lead to an increased understanding of the tumor response to treatment.

Promising Therapeutic Impact of a Selective Estrogen Receptor Downregulator, Fulvestrant, as Demonstrated In Vitro upon Low-Grade Serous Ovarian Carcinoma Cell Lines

Few studies have reported hormonal agent use in the treatment of low-grade serous ovarian carcinomas (LGSOCs), which are chemoresistant. Considering the need for novel effective therapies, we investigated the hormone receptor expression and hormonal inhibition efficacy in LGSOCs. Using immunohistochemistry, we assessed the estrogen receptor (ER) expression status in 33 cases of histologically confirmed serous ovarian tumors, including 10, 11, and 12 cases of LGSOCs, serous borderline tumors (SBTs), and serous cystadenomas (SCAs), respectively. The genetic background reported in our previous study was used in the current study. MPSC1 cells, which were established from LGSOCs, were used in cell proliferation assays. We observed a higher ER expression in LGSOCs and SBTs than in SCAs (70%, 81%, and 50%, respectively). Thus, LGSOCs and SBTs exhibit higher ER expression than SCAs. Moreover, the PIK3CA mutation positively correlated with ER expression in LGSOCs (p = 0.0113). MPSC1 cells showed low ER expression on Western blotting. MPSC1 cell proliferation was significantly inhibited by fulvestrant (a selective ER downregulator). The activation of ER and PI3K/AKT signaling pathways may play an important role in LGSOC carcinogenesis. ER downregulation with fulvestrant or combination therapy with PI3K inhibitors is a possible novel treatment for patients with LGSOCs.

FOXP4 inhibits squamous differentiation of atypical cells in cervical intraepithelial neoplasia via an ELF3‐dependent pathway

AbstractAlthough the human papillomavirus (HPV) vaccine is effective for preventing cervical cancers, this vaccine does not eliminate pre‐existing infections, and alternative strategies have been warranted. Here, we report that FOXP4 is a new target molecule for differentiation therapy of cervical intraepithelial neoplasia (CIN). An immunohistochemical study showed that FOXP4 was expressed in columnar epithelial, reserve, and immature squamous cells, but not in mature squamous cells of the normal uterine cervix. In contrast with normal mature squamous cells, FOXP4 was expressed in atypical squamous cells in CIN and squamous cell carcinoma lesions. The FOXP4‐positive areas significantly increased according to the CIN stages from CIN1 to CIN3. In monolayer cultures, downregulation of FOXP4 attenuated proliferation and induced squamous differentiation in CIN1‐derived HPV 16‐positive W12 cells via an ELF3‐dependent pathway. In organotypic raft cultures, FOXP4‐downregulated W12 cells showed mature squamous phenotypes of CIN lesions. In human keratinocyte‐derived HaCaT cells, FOXP4 downregulation also induced squamous differentiation via an ELF3‐dependent pathway. These findings suggest that downregulation of FOXP4 inhibits cell proliferation and promotes the differentiation of atypical cells in CIN lesions. Based on these results, we propose that FOXP4 is a novel target molecule for nonsurgical CIN treatment that inhibits CIN progression by inducing squamous differentiation.

The 2020 Japan Society of Gynecologic Oncology guidelines for the treatment of ovarian cancer, fallopian tube cancer, and primary peritoneal cancer

The fifth edition of the Japan Society of Gynecologic Oncology guidelines for the treatment of ovarian cancer, fallopian tube cancer, and primary peritoneal cancer was published in 2020. The guidelines contain 6 chapters-namely, (1) overview of the guidelines; (2) epithelial ovarian cancer, fallopian tube cancer, and primary peritoneal cancer; (3) recurrent epithelial ovarian cancer, fallopian tube cancer, and primary peritoneal cancer; (4) borderline epithelial tumors of the ovary; (5) malignant germ cell tumors of the ovary; and (6) malignant sex cord-stromal tumors. Furthermore, the guidelines comprise 5 algorithms-namely, (1) initial treatment for ovarian cancer, fallopian tube cancer, and primary peritoneal cancer; (2) treatment for recurrent ovarian cancer, fallopian tube cancer, and primary peritoneal cancer; (3) initial treatment for borderline epithelial ovarian tumor; (4) treatment for malignant germ cell tumor; and (5) treatment for sex cord-stromal tumor. Major changes in the new edition include the following: (1) revision of the title to "guidelines for the treatment of ovarian cancer, fallopian tube cancer, and primary peritoneal cancer"; (2) involvement of patients and general (male/female) participants in addition to physicians, pharmacists, and nurses; (3) clinical questions (CQs) in the PICO format; (4) change in the expression of grades of recommendation and level of evidence in accordance with the GRADE system; (5) introduction of the idea of a body of evidence; (6) categorization of references according to research design; (7) performance of systematic reviews and meta-analysis for three CQs; and (8) voting for each CQ/recommendation and description of the consensus.

Establishment of a Novel In Vitro and In Vivo Model to Understand Molecular Carcinogenesis of Endometriosis-Related Ovarian Neoplasms

The molecular mechanisms through which endometriosis-related ovarian neoplasms (ERONs) develop from benign endometrioma remain unclear. It is especially a long-standing mystery why ovarian endometrioma has the potential to develop into two representative histological subtypes: endometrioid ovarian carcinoma or clear cell ovarian carcinoma. This study aimed to investigate the molecular carcinogenesis of ERONs using newly developed in vitro and in vivo carcinogenesis models. Epithelial cells were isolated and purified from surgically removed benign endometrioma samples, followed by immortalization by overexpressing cyclinD1/CDK4 in combination with the human TERT gene. Immortalized cells were subjected to various molecular manipulations by combining knockout or overexpression of several candidate drivers, including ARID1A, KRAS, PIK3CA, AKT, and MYC, based on previous comprehensive genome-wide studies of ERONs. These cells were then inoculated into immunocompromised mice and evaluated for malignant transformation. Inoculated cells harboring a combination of three genetic alterations successfully developed tumors with malignant features in mice, whereas those with two genetic manipulations failed to do so. Especially, ARID1A gene knockout, combined with overexpressing the KRAS oncogenic mutant allele (or overexpressing AKT) and c-Myc overexpression led to efficient tumor formation. Of note, these three combinations of genetic alterations produced tumors that histologically represented typical clear cell carcinoma in SCID mice, while the same combination led to tumors with endometrioid histology in nude mice. A combination of ARID1A mutation, KRAS mutation or AKT activation, and c-Myc overexpression were confirmed to be the main candidate drivers for the development of ERONs, as suggested by comprehensive genetic analyses of ERONs. A tumor immune microenvironment involving B-cell signaling may contribute to the diverse histological phenotypes. The present model may help to clarify the molecular mechanisms of ERON carcinogenesis and understand their histological diversity and novel molecular targets.