Shohei Iyoshi

Mesothelial cells promote peritoneal invasion and metastasis of ascites-derived ovarian cancer cells through spheroid formation

Patients with epithelial ovarian cancer (EOC) are often diagnosed with peritoneal metastasis and ascites, the accumulation of intraperitoneal fluid containing nonmalignant cells. However, the interactions between EOC and nonmalignant cells before peritoneal metastasis remain unclear. To investigate this, whole EOC spheroids were observed using a multiphoton microscope, and their invasion ability was assessed. Mesothelial cells were identified as notable components of ascites through morphological assessment, immunohistochemical/immunofluorescence staining, and single-cell RNA sequencing analyses. Almost all EOC cells were spheroids, with 60% containing mesothelial cells. EOC cells quickly generate aggregated spheroids with mesothelial cells, and these aggregated cancer-mesothelial spheroids (ACMSs) invade collagen or mesothelial layers. Mesothelial cells forming ACMSs initiated the invasion. RNA sequencing analysis revealed marked RNA expression changes in mesothelial cells, whereas the changes in EOC cells were minor. Transforming growth factor–β1–stimulated mesothelial cells showed increased invadopodium formation along with fascin-1 up-regulation. These findings suggest that EOC cells alter mesothelial cells through ACMSs, thereby elucidating the rapid spread of EOC in the abdominal cavity.

Microphthalmia-Associated Transcription Factor-Dependent Melanoma Cell Adhesion Molecule Activation Promotes Peritoneal Metastasis of Ovarian Cancer

Ovarian cancer (OvCa) is one of the leading causes of death due to its high metastasis rate to the peritoneum. Recurrent peritoneal tumors also develop despite the use of conventional platinum-based chemotherapies. Therefore, it is still important to explore the factors associated with peritoneal metastasis, as these predict the prognosis of patients with OvCa. In this study, we investigated the function of microphthalmia-associated transcription factor (MITF), which contributes to the development of melanoma, in epithelial ovarian cancer (OvCa). High MITF expression was significantly associated with a poor prognosis in OvCa. Notably, MITF contributed to the motility and invasion of OvCa cells, and specifically with their peri-mesothelial migration. In addition, MITF-positive cells expressed the melanoma cell adhesion molecule (MCAM/CD146), which was initially identified as a marker of melanoma progression and metastasis, and MCAM expression was regulated by MITF. MCAM was also identified as a significant prognostic factor for poor progression-free survival in patients with OvCa. Collectively, our results suggest that MITF is a novel therapeutic target that potentially promotes peritoneal metastasis of OvCa.

Long-term post-recurrence survival outcomes in young women receiving fertility-sparing surgery for epithelial ovarian cancer

The aim of this study was to investigate long-term post-recurrence survival outcomes in young women receiving fertility-sparing surgery (FSS) to verify the feasibility of the limited surgery for epithelial ovarian cancer (OvCa). We performed a regional multicenter retrospective study from January 1986 and March 2020, using clinical data corrected under the central pathological review system. Patients with recurrent tumor after surgery for stage I epithelial OvCa, aged equal or younger than 45 years were included for this study. We evaluated effect of FSS regarding long-term post-recurrence survival with statistical adjustment of propensity score-based method. With the Kaplan-Meier method, original and adjusted survival curves were estimated for recurrence-after survival of patients with (n = 14) and without FSS (n = 26). Median time to disease-specific death was 18.6 months. In both original and adjusted cohorts, there were no significant difference between the two groups (log rank test; P > 0.05). Hazard ratio of disease-specific death was 1.264 (95% confidence interval, 0.563-2.836; P = 0.570) in original and 1.354 (95% confidence interval, 0.702-2.611; P = 0.366) in adjusted population. This result indicated that patients with FSS was not associated with poorer prognosis for recurrence-after survival than those without. When comparing patients not receiving FSS, patients receiving FSS with recurrence at spared ovary followed not significantly different survival outcome as well as those with extra-ovarian recurrence. There was no significant difference of long-term post-recurrence survival outcomes between patients of epithelial OvCa with and without FSS in young women of reproductive age.

Pro‐tumoral behavior of omental adipocyte‐derived fibroblasts in tumor microenvironment at the metastatic site of ovarian cancer

AbstractAdipocyte‐rich omentum offers “good soil” for disseminating ovarian cancer (OvCa), contributing to therapeutic difficulty. However, little is understood about the association between adipocytes and tumor growth at peritoneal dissemination site. Herein, we report the induction of adipocyte dedifferentiation by OvCa cells and pro‐tumorigenic effects of resulted adipocyte‐derived fibroblasts. We confirmed that malignant ascites promoted the dedifferentiation of the primary human adipocytes obtained from surgical omental specimen into omental adipocyte‐derived fibroblast (O‐ADF) that possess both mesenchymal stem cell and myofibroblast‐like features. This promotion of dedifferentiation by malignant ascites was blocked by addition of Wnt signaling inhibitor. The effects of dedifferentiated adipocytes in proliferation and migration of OvCa cells were analyzed with in vitro coculturing experimental models and in vivo mice model, and we demonstrated that OvCa cell lines showed enhanced proliferative characteristics, as well as increased migratory abilities upon coculturing with O‐ADF. Additionally, exogenous transforming growth factor‐β1 augmented desmoplastic morphological change of O‐ADF, leading to higher proliferative ability. Our results suggest that OvCa cells promote dedifferentiation of peritoneal adipocytes by activating Wnt/β‐catenin signaling, and generated O‐ADFs exhibit pro‐tumoral hallmarks.

Impact of incomplete surgery and adjuvant chemotherapy for the intraoperative rupture of capsulated stage I epithelial ovarian cancer: a multi-institutional study with an in-depth subgroup analysis

The aim of the present study was to examine the effects of incomplete surgery and adjuvant chemotherapy on the prognosis of patients with intraoperative rupture of capsulated stage I epithelial ovarian cancer (OvCa). A regional retrospective study was conducted between 1986 and 2019. Among 4,730 patients with malignant ovarian tumors, 534 women with International Federation of Gynecology and Obstetrics stage IA and IC1 epithelial OvCa were eligible. Differences in survival outcomes were examined between patients with stage IA and IC1 tumors and the effects of uterine preservation, complete-staging lymphadenectomy, and adjuvant chemotherapy were investigated by an in-depth subgroup analysis. To analyze therapeutic effects, baseline imbalances were adjusted using propensity score (PS). The prognosis of patients with stage IC1 tumors was worse than those with stage IA. Surgical spill did not affect the site of recurrence. In the PS-adjusted subgroup analysis, uterine preservation (hazard ratio [HR]=1.669; 95% confidence interval [CI]=1.052-2.744), incomplete-staging lymphadenectomy (HR=1.689; 95% CI=1.211-2.355), and the omission of adjuvant chemotherapy (HR=3.729; 95% CI=2.090-6.653) significantly increased the HR of recurrence for patients with stage IC1 tumors compared to those with stage IA tumors. Adjuvant chemotherapy decreased the impact of rupture with uterine preservation (HR=0.159; 95% CI=0.230-1.168) or incomplete-staging lymphadenectomy (HR=0.987; 95% CI=0.638-1.527). The present results suggest intraoperative rupture of capsulated stage I epithelial OvCa is associated with a poor prognosis. When chemotherapy is given for patients receiving incomplete surgery, there is no longer an increased risk of recurrence observed with the rupture.

Obesity contributes to the stealth peritoneal dissemination of ovarian cancer: a multi‐institutional retrospective cohort study

AbstractObjectiveThe clinical significance of a higher BMI on the prognosis of ovarian cancer remains controversial; therefore, a more detailed analysis is demanded. This study investigated the impact of BMI on peritoneum‐specific recurrence to clarify the involvement of adipose tissue in the proliferation of cancer cells at sites of peritoneal dissemination.MethodsAmong 4,730 patients with malignant ovarian tumors, 280 diagnosed with International Federation of Gynecology and Obstetrics (FIGO) stage IIB to IIIC epithelial ovarian cancer and who underwent complete resection in the primary surgery were included in the present study.ResultsThere were 42, 201, and 37 women in the low, normal, and high BMI groups, respectively. Peritoneum‐specific recurrence‐free survival and overall survival were both significantly shorter in patients with a high BMI than in those with a normal BMI (p = 0.028 and 0.018, respectively). No significant differences were observed in the distribution of sites of recurrence between these two groups. A multivariate analysis identified obesity as an independent prognostic factor in addition to pT3 tumor staging and positive ascites cytology.ConclusionsPatients with a high BMI had a significantly worse prognosis than those with a normal BMI, and peritoneal adipose tissue may have contributed to this difference.

Metastatic Voyage of Ovarian Cancer Cells in Ascites with the Assistance of Various Cellular Components

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and has a unique metastatic route using ascites, known as the transcoelomic root. However, studies on ascites and contained cellular components have not yet been sufficiently clarified. In this review, we focus on the significance of accumulating ascites, contained EOC cells in the form of spheroids, and interaction with non-malignant host cells. To become resistant against anoikis, EOC cells form spheroids in ascites, where epithelial-to-mesenchymal transition stimulated by transforming growth factor-β can be a key pathway. As spheroids form, EOC cells are also gaining the ability to attach and invade the peritoneum to induce intraperitoneal metastasis, as well as resistance to conventional chemotherapy. Recently, accumulating evidence suggests that EOC spheroids in ascites are composed of not only cancer cells, but also non-malignant cells existing with higher abundance than EOC cells in ascites, including macrophages, mesothelial cells, and lymphocytes. Moreover, hetero-cellular spheroids are demonstrated to form more aggregated spheroids and have higher adhesion ability for the mesothelial layer. To improve the poor prognosis, we need to elucidate the mechanisms of spheroid formation and interactions with non-malignant cells in ascites that are a unique tumor microenvironment for EOC.

Peritoneal restoration by repurposing vitamin D inhibits ovarian cancer dissemination via blockade of the TGF-β1/thrombospondin-1 axis

Ovarian cancer (OvCa), a lethal gynecological malignancy, disseminates to the peritoneum. Mesothelial cells (MCs) act as barriers in the abdominal cavity, preventing the adhesion of cancer cells. However, in patients with OvCa, they are transformed into cancer-associated mesothelial cells (CAMs) via mesenchymal transition and form a favorable microenvironment for tumors to promote metastasis. However, attempts for restoring CAMs to their original state have been limited. Here, we investigated whether inhibition of mesenchymal transition and restoration of MCs by vitamin D suppressed the OvCa dissemination in vitro and in vivo. The effect of vitamin D on the mutual association of MCs and OvCa cells was evaluated using in vitro coculture models and in vivo using a xenograft model. Vitamin D restored the CAMs, and thrombospondin-1 (component of the extracellular matrix that is clinically associated with poor prognosis and is highly expressed in peritoneally metastasized OvCa) was found to promote OvCa cell adhesion and proliferation. Mechanistically, TGF-β1 secreted from OvCa cells enhanced thrombospondin-1 expression in CAMs via Smad-dependent TGF-β signaling. Vitamin D inhibited mesenchymal transition in MCs and suppressed thrombospondin-1 expression via vitamin D receptor/Smad3 competition, contributing to the marked reduction in peritoneal dissemination in vivo. Importantly, vitamin D restored CAMs from a stabilized mesenchymal state to the epithelial state and normalized thrombospondin-1 expression in preclinical models that mimic cancerous peritonitis in vivo. MCs are key players in OvCa dissemination and peritoneal restoration and normalization of thrombospondin-1 expression by vitamin D may be a novel strategy for preventing OvCa dissemination.