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.

Background: This study aimed to compare the oncologic and surgical outcomes of patients treated with robot-assisted modified radical hysterectomy (RAMRH) and total laparoscopic modified radical hysterectomy (TLMRH) for endometrial cancer (EC) with those of patients treated with abdominal modified radical hysterectomy (AMRH). Methods: We performed a retrospective analysis of 133 patients with early-stage EC who underwent different surgical approaches (RAMRH, n = 14; TLMRH, n = 94; AMRH, n = 25) between 2018 and 2021 at Shimane University Hospital. The data on clinical outcomes, including estimated blood loss, duration of surgery, duration of hospital stay, and number of dissected lymph nodes were collected from the patients’ electronic medical records. Kaplan–Meier curves were used to plot survival data, and log-rank tests were used to determine the statistical significance of differences in survival rates. Results: RAMRH showed the lowest bleeding volume (RAMRH: 95 ± 123.21 mL; TLMRH: 140.74 ± 172.60 mL; AMRH: 482.6 ± 429 mL) and shortest hospital stay (RAMRH: 6.43 ± 1.09 days; TLMRH: 7.30 ± 3.39 days; AMRH: 9.88 ± 2.65 days) among the three groups. The number of dissected lymph nodes tended to be higher in the RAMRH group than that in the TLMRH or AMRH group. The different surgical approaches did not correlate with progression-free survival and overall survival. Conclusions: Both RAMRH and TLMRH are safe, feasible, innovative, and minimally invasive surgical alternatives to AMRH for patients with EC.

Although endometriosis is a benign disease, it is associated with cancer-related gene mutations, such as KRAS or PIK3CA. Endometriosis is associated with elevated levels of inflammatory factors that cause severe pain. In a previous study, we demonstrated that KRAS or PIK3CA mutations are associated with the activation of cell proliferation, migration, and invasion in a patient-derived immortalized endometriotic cell line, HMOsisEC10. In this study, we investigated the effects of these mutations on progesterone resistance. Since the HMOsisEC10 had suppressed progesterone receptor (PR) expression, we transduced PR-B to HMOsisEc10 cell lines including KRAS mutant and PIK3CA mutant cell lines. We conducted a migration assay, invasion assay, and MTT assay using dienogest and medroxyprogestrone acetate. All cell lines showed progesterone sensitivity with or without mutations. Regarding inflammatory factors, real-time quantitative RT-PCR revealed that the KRAS mutation cell line exhibited no suppression of Cox-2 and mPGES-1 on progesterone treatment, whereas IL-6, MCP-1, VEGF, and CYP19A1 were significantly suppressed by progesterone in both mutated cell lines. Our results suggest that KRAS mutation and PIK3CA mutation in endometriotic cells may not be associated with progesterone resistance in terms of aggressiveness. However, KRAS mutations may be associated with progesterone resistance in the context of pain.

Ovarian cancer is classified as type 1 or 2, representing low- and high-grade serous carcinoma (LGSC and HGSC), respectively. LGSC arises from serous borderline tumor (SBT) in a stepwise manner, while HGSC develops from serous tubal intraepithelial carcinoma (STIC). Rarely, HGSC develops from SBT and LGSC. Herein, we describe the case of a patient with HGSC who presented with SBT and LGSC, and in whom we analyzed the molecular mechanisms of carcinogenesis. We performed primary debulking surgery, resulting in a suboptimal simple total hysterectomy and bilateral salpingo-oophorectomy due to strong adhesions. The diagnosis was stage IIIC HGSC, pT3bcN0cM0, but the tumor contained SBT and LGSC lesions. After surgery, TC (Paclitaxel + Carbopratin) + bevacizumab therapy was administered as adjuvant chemotherapy followed by bevacizumab as maintenance therapy. The tumor was chemo-resistant and caused ileus, and bevacizumab therapy was conducted only twice. Next-Generation Sequencing revealed KRAS (p.G12V) and NF2 (p.W184*) mutations in all lesions. Interestingly, the TP53 mutation was not detected in every lesion, and immunohistochemistry showed those lesions with wild-type p53. MDM2 was amplified in the HGSC lesions. DNA methylation analysis did not show differentially methylated regions. This case suggests that SBT and LGSC may transform into HGSC via p53 dysfunction due to MDM2 amplification.

Background: AT-rich interaction domain 1A (ARID1A) has been proposed as a new biomarker for predicting response to immune checkpoint inhibitors (ICIs). The predictive value of ARID1A for predicting ICI effectiveness has not been reported for endometrial cancer. Therefore, we investigated whether ARID1A negativity predicts ICI effectiveness for endometrial cancer treatment. Methods: We evaluated ARID1A expression, tumor-infiltrating lymphocytes (CD8+), and immune checkpoint molecules (PD-L1/PD-1) by immunostaining endometrial samples from patients with endometrial cancer. Samples in which any of the four mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2) were determined to be negative via immunostaining were excluded. In the ARID1A-negative group, microsatellite instability (MSI) status was confirmed via MSI analysis. Results: Of the 102 samples investigated, 25 (24.5%) were ARID1A-negative. CD8 and PD-1 expression did not differ significantly between the ARID1A-negative group and the ARID1A-positive group; however, the ARID1A-negative group showed significantly lower PD-L1 expression. Only three samples (14.2%) in the ARID1A-negative group showed high MSI. Sanger sequencing detected three cases of pathological mutation in the MSH2-binding regions. We also established an ARID1A-knockout human ovarian endometriotic epithelial cell line (HMOsisEC7 ARID1A KO), which remained microsatellite-stable after passage. Conclusion: ARID1A negativity is not suitable as a biomarker for ICI effectiveness in treating endometrial cancer.

Type II endometrial cancer (EC) is responsible for most endometrial cancer-related deaths due to its aggressive nature, late-stage detection, and high tolerance to standard therapies. Thus, novel treatment strategies for type II EC are imperative. For patients with mismatch repair-deficient (dMMR) tumors, immunotherapy with immune checkpoint inhibitors represents a promising therapeutic strategy. However, the prevalence of dMMR tumors in type II EC patients remains unclear. In this study, using immunohistochemistry, we evaluated the expression of mismatch repair (MMR) proteins, tumor-infiltrating lymphocytes (CD8+), and immune checkpoint molecules (PD-L1) in 60 patients with type II EC (16, 5, 17, and 22 were endometrioid G3, serous, de-differentiated, and carcinosarcoma cases, respectively) to investigate the therapeutic effect of immune checkpoint inhibitors. Approximately 24 cases (40%) had a loss of MMR protein expression. The positivity rate of CD8+ (p = 0.0072) and PD-L1 (p = 0.0061) expression was significantly associated with the dMMR group. These results suggest immune checkpoint inhibitors (anti-PD-L1/PD-1 antibodies) could effectively treat type II EC with dMMR. The presence of dMMR might be a biomarker for a positive response to PD-1/PD-L1 immunotherapy in type II EC.

Background: Since malignant struma ovarii is a very rare disease, its carcinogenic mechanism has not been elucidated. Here, we sought to identify the genetic lesions that may have led to the carcinogenesis of a rare case of malignant struma ovarii (follicular carcinoma) with peritoneal dissemination. Methods: DNA was extracted from the paraffin-embedded sections of normal uterine tissues and malignant struma ovarii for genetic analysis. Whole-exome sequencing and DNA methylation analysis were then performed. Results: Germline variants of RECQL4, CNTNAP2, and PRDM2, which are tumor-suppressor genes, were detected by whole-exome sequencing. Somatic uniparental disomy (UPD) was also observed in these three genes. Additionally, the methylation of FRMD6-AS2, SESN3, CYTL1, MIR4429, HIF3A, and ATP1B2, which are associated with tumor growth suppression, was detected by DNA methylation analysis. Conclusions: Somatic UPD and DNA methylation in tumor suppressor genes may be associated with the pathogenesis of malignant struma ovarii. To our knowledge, this is the first report of whole-exome sequencing and DNA methylation analysis in malignant struma ovarii. Genetic and DNA methylation analysis may help elucidate the mechanism of carcinogenesis in rare diseases and guide treatment decisions.

Recent 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.

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.

Herein, we present the successful treatment of a 92-year-old woman who experienced recurrent EC in the vaginal stump and para-aortic lymph nodes. The patient was first treated with paclitaxel and carboplatin for recurrent EC, which was abandoned after two cycles of chemotherapy because of G4 hematologic toxicity. Later, the patient was treated with letrozole for early-stage breast cancer, which was diagnosed simultaneously with EC recurrence. After four months of hormonal therapy, a partial response was observed not only in the lesions in the breast, but also those in the vaginal stump and para-aortic lymph nodes. She had no recurrence of breast cancer or EC, even after six years of treatment with letrozole-based hormonal therapy. Subsequent whole-exome sequencing using the genomic DNA isolated from the surgical specimen in the uterine tumor identified several genetic variants, including actionable mutations, such as CTNNB1 (p.S37F), PIK3R1 (p.M582Is_10), and TP53 c.375 + 5G>T. These data suggest that the efficacy of letrozole is mediated by blocking the mammalian target of the rapamycin pathway. The findings of this study, substantiated via genetic analysis, suggest the possibility of long-term disease-free survival, even in elderly patients with recurrent EC, which was thought to be difficult to cure completely.

The survival of patients with advanced or recurrent ovarian cancer has improved tremendously in the past decade, mainly due to the establishment of maintenance therapy with poly (ADP-ribose) polymerase (PARP) inhibitors (PARPis) after conservative chemotherapies. Despite their superior efficacy, resistance to PARPis has been reported, and patients with resistance have a much worse prognosis. Therefore, the development of novel treatment strategies to overcome PARPi resistance is urgently needed. The present review article focuses on the molecular mechanisms of how PARPis exert cytotoxic effects on cancer cells through DNA repair processes, especially the genetic background and tumor microenvironment favored by PARPis. Furthermore, currently available information on PARPi resistance mechanisms is introduced and discussed to develop a novel therapeutic approach against them.

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.

Despite the knowledge about numerous genetic mutations essential for the progression of low-grade serous ovarian carcinoma (LGSOC), the specific combination of mutations required remains unclear. Here, we aimed to recognize the oncogenic mutations responsible for the stepwise development of LGSOC using immortalized HOVs-cyst-1 cells, developed from ovarian serous cystadenoma cells, and immortalized via cyclin D1, CDK4R24C, and hTERT gene transfection. Furthermore, oncogenic mutations, KRAS and PIK3CA, were individually and simultaneously introduced in immortalized HOV-cyst-1 cells. Cell functions were subsequently analyzed via in vitro assays. KRAS or PIK3CA double mutant HOV-cyst-1 cells exhibited higher cell proliferation and migration capacity than the wild-type cells, or those with either a KRAS or a PIK3CA mutation, indicating that these mutations play a causative role in LGSOC tumorigenesis. Moreover, KRAS and PIK3CA double mutants gained tumorigenic potential in nude mice, whereas the cells with a single mutant exhibited no signs of tumorigenicity. Furthermore, the transformation of HOV-cyst-1 cells with KRAS and PIK3CA mutants resulted in the development of tumors that were grossly and histologically similar to human LGSOCs. These findings suggest that simultaneous activation of the KRAS/ERK and PIK3CA/AKT signaling pathways is essential for LGSOC development.

Endometriosis-harboring cancer-associated somatic mutations of PIK3CA and KRAS provides new opportunities for studying the multistep processes responsible for the functional and molecular changes in this disease. We aimed to establish a novel in vitro endometriosis model to clarify the functional behavior and molecular pathogenesis of this disorder. Immortalized HMOsisEC10 human ovarian endometriotic epithelial cell line was used in which KRAS and PIK3CA mutations were introduced. Migration, invasion, proliferation, and microarray analyses were performed using KRAS and PIK3CA mutant cell lines. In vitro assays showed that migration, invasion, and proliferation were significantly increased in KRAS and PIK3CA mutant cell lines, indicating that these mutations played causative roles in the aggressive behavior of endometriosis. Microarray analysis identified a cluster of gene signatures; among them, two significantly upregulated cancer-related genes, lysyl oxidase (LOX) and pentraxin3 (PTX3), were associated with cell proliferation, invasion, and migration capabilities. Furthermore, siRNA knockdown of the two genes markedly reduced the metastatic ability of the cells. These results suggest that endometriosis with KRAS or PIK3CA mutations can significantly enhance cell migration, invasion, and proliferation by upregulating LOX and PTX3. We propose that LOX and PTX3 silencing using small molecules could be an alternative therapeutic regimen for severe endometriosis.