Peritoneal Metastasis Of Ovarian Cancer Research Articles

Abstract 6527: Fucosyltransferase 5 promotes immune evasion in ovarian cancer by suppressing double negative T cells

Abstract Emerging evidence suggests that aberrant glycosylation in cancer impact on various stages in the disease progression including immunomodulation, but the underlying mechanisms remain poorly understood. Our previous data demonstrated that fucosyltransferase 5 (FUT5), a glycosyltransferase responsible for the terminal step in synthesizing Lewis antigens, may contribute to peritoneal metastasis of ovarian cancer. In this study, using clinical samples of high grade serous ovarian cancer (HGSOC), the most common subtype, we found that high expression of FUT5 is associated with a worse outcome. By employing multiplex immunohistochemistry (IHC) to examine T cell subsets, we found a significant decrease in CD3+CD4−CD8− (double negative, DN) T cells in FUT5high (n=10) compared to FUT5low samples (n=10), while there is no difference in the abundance of CD8+ cytotoxic T cells, CD4+ helper T cells or CD4+Foxp3+ regulatory T cells. Tumor-infiltrating DN T cells has been shown to mediate potent anti-tumor response. In addition to their cytotoxic capabilities, DN T cells largely exhibit modulatory functions on other T cell subsets. To further investigate, we performed additional IHC staining and observed a significant increase in proliferating (Ki67+) CD8+ tissue resident memory cells, which are known to be important for cancer immunity. In addition, we observed a decrease in metastases in the FUT5 knockdown group, accompanied by an increase in DN T cells in ascites and omental metastatic tumors in humanised mice, as revealed by flow cytometry, confirming a direct immunomodulatory role of FUT5. Together, these findings reveal a novel role of FUT5 in promoting immune evasion by suppressing anti-tumor DN T cells, which could provide novel insights for immunotherapy in HGSOC, which has a low response rate to immune checkpoint inhibitors (This research is supported by RGC SRFS2223-7S05, HMRF 08192286 and LSCCB under the Health@InnoHK Program launched by ITC, HKSAR). Citation Format: S. W. Fung, Sally K. Y. To, A. A. Hassan, Phillip P.C. Ip, Alice S. T. Wong. Fucosyltransferase 5 promotes immune evasion in ovarian cancer by suppressing double negative T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6527.

Senolytic drugs dasatinib and quercetin combined with Carboplatin or Olaparib reduced the peritoneal and adipose tissue metastasis of ovarian cancer

Chemotherapy and targeted drugs-induced senescent ovarian cancer cells that accumulate in peritoneal adipose tissue contribute significantly to chronic inflammation, disrupt homeostasis, and may fuel various aspects of cancer progression. However, the pro-senescence effects of chemotherapy and targeted drugs on adipose derived stem cells (ADSCs) within peritoneal adipose tissue remain poorly understood. In this study, we show that the first-line chemotherapy and targeted drugs can induce the cellular senescence of ADSCs in vitro and increase the aging of peritoneal adipose tissue in vivo. These treatments significantly promoted the dysregulation of glucose and lipid metabolism, including insulin resistance and liver lipid accumulation. Our study shows that dasatinib and quercetin, as senolytics, effectively restore glucose homeostasis in mice with ovarian cancer and significantly reduce adipose tissue aging. Importantly, combining these drugs with Carboplatin or Olaparib results in a marked decrease in both peritoneal and adipose tissue metastasis of ovarian cancer cells. Mechanistically, we revealed that there is crosstalk between ovarian cancer cells and senescent ADSCs. The crosstalk increases inflammatory cytokines and chemokines production in ADSCs and notably upregulates chemokine receptors on cancer cells. Collectively, these data indicate that senescent ADSCs induced by chemotherapy and targeted therapy drugs impair adipose tissue function. However, the senolytic drugs dasatinib and quercetin, can significantly ameliorate organ aging and damage induced by these treatments. Notably, dasatinib and quercetin combined with Carboplatin or Olaparib reduced the peritoneal and adipose tissue metastasis of ovarian cancer, ultimately benefiting the mice undergoing chemotherapy and targeted therapy.

Abstract B091: Mechanisms underlying the omental support of ovarian cancer peritoneal metastasis

Abstract More than 80% of ovarian cancer (OC) cases have metastasized to the peritoneal cavity at diagnosis. The five-year survival rate for these patients is 25%. Within the peritoneal cavity, the most common and early site of metastasis is the omentum, a well-vascularized, specialized adipose tissue that arises off the greater curvature of the stomach. Because OC homes to the omentum, it is removed as a standard of care for patients with peritoneal metastases. In mouse models, the omentum is also an early metastatic site, and omentectomy reduces tumor expansion. The mechanism by which the omentum promotes OC growth is unknown, perhaps due to the complex omental microenvironment. The omentum contains many features that could impact OC seeding. It is covered by a mesothelial lining that extends in a sheet anchoring the omentum to surrounding tissues and is highly perfused by blood vessels. It contains lymphoid aggregates or milky spots that may contribute to pro- and anti-tumor immunity. This study explores the association of OC metastases with specific omentum features. We intraperitoneally injected luciferase-expressing ID8 OC cells to mimic high-grade serous OC metastasis. Using high-resolution, spatial ex vivo bioluminescence imaging (BLI), we found that tumor nodules preferentially formed in adipocyte-rich regions of the omentum and the mesentery, another peritoneal tissue favorable for OC seeding. To determine whether adipocytes, the most abundant omental cell type, are the primary support of OC, we crossed Adiponectin Cre+ and DTA mice to generate mice lacking white and brown adipocytes from birth. To overcome the metabolic syndrome the fatless mice develop, they receive subcutaneous fat transplants dorsally, referred to as distal adipocyte rescue of lipodystrophy (DARL) mice. Littermate controls receive sham surgeries. The blood triglyceride, glucose, and insulin levels are normalized post-transplant. Thus, the peritoneal cavity lacks mature adipocytes, but the mice have typical metabolic profiles, allowing us to study the role of omental adipocytes in peritoneal metastasis. Once the mice recovered from surgery, they were intraperitoneally injected with luciferase-expressing ID8s. While it was hypothesized that OC metastatic seeding within the adipocyte-free omentum and associated peritoneum would be impaired without local mature adipocytes, BLI revealed that the tumor burden was not decreased in DARL mice. Notably, specific regions of OC seeding, where mature adipocytes would have localized if present, such as the omentum and mesentery, retained tumor nodules in DARL mice. This conserved OC localization suggests that other cells in this specific microenvironment might be responsible for metastatic spread. To identify these cells, studies are ongoing to profile these regions in the DARL and control mice via flow cytometry and single-cell RNA sequencing. By unraveling the support for OC cells in the omentum, therapeutic strategies can be identified to repolarize the metastatic milieu and halt further spread to improve patient outcomes. Citation Format: Rachel Mintz, Alexandre Gallerand, Jichang Han, Sarah Ning, Wei Zou, Mary Wohltmann, Bernd Zinselmeyer, Gwendalyn Randolph. Mechanisms underlying the omental support of ovarian cancer peritoneal metastasis [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B091.

Prognostic value of peritoneal scar-like tissue in patients with peritoneal metastases of ovarian origin presenting for curative-intent cytoreductive surgery

BackgroundComplete cytoreductive surgery (CRS), remain the gold standard in the treatment of peritoneal metastases of ovarian cancer (PMOC). Given the increasing rate of neoadjuvant chemotherapy in patients with high PCI, prior abdominal surgeries, inflammation and fibrotic changes, the benefit of removing any “peritoneal scar-like tissues” (PST) during CRS, hasn’t been thoroughly investigated. Our objective in this retrospective cohort was to identify the proportion of malignant cells positivity in PST of patients with PMOC, undergoing curative-intent CRS ± HIPEC.MethodsThis is a retrospective study, conducted at our comprehensive cancer center, including patients with PMOC, presenting for curative-intent CRS. During CRS, benign-looking peritoneal lesions, lacking the typical hard nodular, aggressive, and invasive morphology, were systematically resected or electro fulgurated. PSTs were analyzed for the presence of tumoral cells by our pathologist. Correlations between the presence of PST and their positivity, and the different patients’ variables, were studied.ResultsIn 51% of patients, PST harbored malignant cells. Those were associated with poorly differentiated serous tumors, a high PCI (> 8) and a worse DFS: 17 months in the positive PST group versus 29 months in the negative PST group (p = 0.05), on univariate analysis. Multivariate analysis revealed that PCI > 8 and poorly differentiated primary tumor histology were correlated with a worse DFS, and that higher PCI and advanced FIGO were correlated with a worse OS.ConclusionBenign-looking PST harbors malignancy in 51% of cases. The benefit of their systematic resection and their prognostic value should be further investigated in larger cohorts.

EZH2 Contributes to Anoikis Resistance and Promotes Epithelial Ovarian Cancer Peritoneal Metastasis by Regulating m6A.

Histone modification has a significant effect on gene expression. Enhancer of zeste homolog 2 (EZH2) contributes to the epigenetic silencing of target chromatin through its roles as a histone-lysine N-methyltransferase enzyme. The development of anoikis resistance in tumor cells is considered to be a critical step in the metastatic process of primary malignant tumors. The purpose of this study was to investigate the effect and mechanism of anoikis resistance in ovarian adenocarcinoma peritoneal metastasis. In addition to examining EZH2 protein expression in ovarian cancer omental metastatic tissues, we established a model of ovarian cancer cell anoikis and a xenograft tumor model in nude mice. Anoikis resistance and ovarian cancer progression were tested after EZH2 and N6-methyladenosine (m6A) levels were modified. EZH2 expression was significantly higher in ovarian cancer omental metastatic tissues than in normal ovarian tissues. Reducing the level of EZH2 decreased the level of m6A and ovarian cancer cell anoikis resistance in vitro and inhibited ovarian cancer progression in vivo. M6a regulation altered the effect of EZH2 on anoikis resistance. Our results indicate that EZH2 contributes to anoikis resistance and promotes ovarian adenocarcinoma abdominal metastasis by m6A modification. Our findings imply the potential of the clinical application of m6A and EZH2 for patients with ovarian cancer.

Prognostic value of preoperative serological biomarkers in patients undergoing cytoreductive surgery for ovarian cancer peritoneal metastases.

Peritoneal metastases of ovarian cancer (PMOC) are common at initial presentation. Cytoreductive surgery (CRS) of curative intent has been proven to be efficient in increasing the overall survival (OS) and the disease-free survival (DFS) of these patients. Nevertheless, CRS is associated with high postoperative morbidity, which makes patient selection a major concern. Appropriate prognostic factors that can predict patient outcomes after surgery are still lacking. Preoperative biomarkers and their ratios have been shown to be predictive of patient prognosis for various solid tumors. We aimed to study their correlation with the prognosis of patients undergoing CRS for PMOC. This retrospective study included patients with PMOC operated by CRS. Preoperative biomarkers and other clinicopathological characteristics were studied to determine their prognostic value in terms OS and DFS. 216 patients were included. Patients with preoperative hemoglobin (Hb) <11.7 g/dL had a poorer prognosis in terms of OS (p=0.0062) and DFS (p=0.0077). Additionally, increased neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR) >0.32, and platelet-to-lymphocyte ratio (PLR) >214.5 were associated with worse OS (p=0.022, p=0.0028, and p=0.0018, respectively) and worse DFS (p=0.028, p=0.003, and p=0.019, respectively). Multivariate analysis showed that the variables mentioned above were independent predictive factors for OS and DFS. Preoperative Hb level, NLR, MLR, and PLR are prognostic factors for OS and DFS in PMOC patients operated by curative CRS.

Deep epigastric lymph nodes implication in patients’ recurrence pattern after cytoreductive surgery in ovarian peritoneal metastases

IntroductionAlthough complete cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC) offers a good prognosis in patients with peritoneal metastasis of ovarian cancer (PMOC), recurrences are quite common. These recurrences can be intra-abdominal or systemic in nature. Our objective was to study and illustrate the global recurrence pattern in patients operated for PMOC, shedding light on a previously overlooked lymphatic basin at the level of the epigastric artery, the deep epigastric lymph nodes (DELN) basin. Patients and methodsThis was a retrospective study including patients with PMOC who underwent surgery with curative-intent, from 2012 until 2018, at our cancer center, and who presented with any type of disease recurrence on follow-up. CT-scans, MRIs and PET-scans were reviewed in order to determine solid organs and lymph nodes (LN) recurrences. ResultsDuring the study period, 208 patients underwent CRS ± HIPEC, 115 (55.3%) presented with organ or lymphatic recurrence over a median follow-up of 81 months. Sixty percent of these patients had radiologically enlarged LN involvement. The pelvis/pelvic peritoneum was the most common intra-abdominal organ recurrence site (47%), while the retroperitoneal LN was the most common lymphatic recurrence site (73.9%). Previously overlooked DELN were found in 12 patients, with 17.4% implication in lymphatic basin recurrence patterns. ConclusionOur study revealed the potential role of the DELN basin, previously overlooked in the systemic dissemination process of PMOC. This study sheds light on a previously unrecognized lymphatic pathway, as an intermediate checkpoint or relay, between the peritoneum, an intra-abdominal organ, and the extra-abdominal compartment.

Omental cancer-associated fibroblast-derived exosomes with low microRNA-29c-3p promote ovarian cancer peritoneal metastasis.

Ovarian cancer (OC) is characterized by frequent widespread peritoneal metastasis. Cancer-associated fibroblasts (CAFs) represent a critical stromal component of metastatic niche and promote omentum metastasis in OC patients. However, the role of exosomes derived from omental CAFs in metastasis remains unclear. We isolated exosomes from primary omental normal fibroblasts (NFs) and CAFs from OC patients (NF-Exo and CAF-Exo, respectively) and assessed their effect on metastasis. In mice bearing orthotopic OC xenografts, CAF-Exo treatment led to more rapid intraperitoneal tumor dissemination and shorter animal survival. Similar results were observed in mice undergoing intraperitoneal injection of tumor cells. Among the miRNAs downregulated in CAF-Exo, miR-29c-3p in OC tissues was associated with metastasis and survival in patients. Moreover, increasing miR-29c-3p in CAF-Exo significantly weakened the metastasis-promoting effect of CAF-Exo. Based on RNA sequencing, expression assays, and luciferase assays, matrix metalloproteinase 2 (MMP2) was identified as a direct target of miR-29c-3p. These results verify the significant contribution of exosomes from omental CAFs to OC peritoneal metastasis, which could be partially due to the relief of MMP2 expression inhibition mediated by low exosomal miR-29c-3p.

New Insights into Ferroptosis Initiating Therapies (FIT) by Targeting the Rewired Lipid Metabolism in Ovarian Cancer Peritoneal Metastases

Ovarian cancer is one of the most lethal gynecological cancers worldwide. The poor prognosis of this malignancy is substantially attributed to the inadequate symptomatic biomarkers for early diagnosis and effective remedies to cure the disease against chemoresistance and metastasis. Ovarian cancer metastasis is often relatively passive, and the single clusters of ovarian cancer cells detached from the primary ovarian tumor are transcoelomic spread by the peritoneal fluid throughout the peritoneum cavity and omentum. Our earlier studies revealed that lipid-enriched ascitic/omental microenvironment enforced metastatic ovarian cancer cells to undertake metabolic reprogramming and utilize free fatty acids as the main energy source for tumor progression and aggression. Intriguingly, cell susceptibility to ferroptosis has been tightly correlated with the dysregulated fatty acid metabolism (FAM), and enhanced iron uptake as the prominent features of ferroptosis are attributed to the strengthened lipid peroxidation and aberrant iron accumulation, suggesting that ferroptosis induction is a targetable vulnerability to prevent cancer metastasis. Therefore, the standpoints about tackling altered FAM in combination with ferroptosis initiation as a dual-targeted therapy against advanced ovarian cancer were highlighted herein. Furthermore, a discussion on the prospect and challenge of inducing ferroptosis as an innovative therapeutic approach for reversing remedial resistance in cancer interventions was included. It is hoped this proof-of-concept review will indicate appropriate directions for speeding up the translational application of ferroptosis-inducing compounds (FINs) to improve the efficacy of ovarian cancer treatment.

ALG3 Promotes Peritoneal Metastasis of Ovarian Cancer through Increasing Interaction of α1,3-mannosylated uPAR and ADAM8.

Peritoneal metastasis is the main cause of poor prognoses and high mortality in ovarian cancer patients. Abnormal protein glycosylation modification is associated with cancer malignancy. Elevated α1,3-mannosyltransferase 3 (ALG3), which catalyzes the α1,3-mannosylation of glycoproteins, has been found in some malignant tumors. However, the pathological significance of ALG3 and its regulatory mechanism in ovarian cancer metastasis is unclear. The results showed that the level of ALG3/α1,3-mannosylation was higher in human ovarian cancer tissues compared with normal ovarian tissues, as measured by Lectin chip, Western blot and Lectin blot analyses, as well as ovarian tissue microarray analysis. ALG3 was also correlated with the poor prognosis of ovarian cancer patients, according to survival analysis. The downregulation of ALG3 decreased the proliferation, stemness and peritoneal metastasis of ovarian cancer cells. The increase in urokinase plasminogen activator receptor (uPAR) α1,3-mannosylation catalyzed by ALG3 enhanced urokinase plasminogen activator (uPA)/uPAR activation and the interaction of uPAR with a disintegrin and metalloproteinase 8 (ADAM8), which promoted ovarian cancer peritoneal metastasis via the ADAM8/Ras/ERK pathway. Furthermore, decreased ALG3 suppressed ascites formation and the peritoneal metastasis of ovarian cancer cells in mice. This study highlights ALG3 as a potential diagnostic biomarker and prospective therapeutic target for ovarian cancer.

568P First-in-human anti-ALPP CAR-T cell immunotherapy for ovarian and endometrial cancer

Ovarian and endometrial cancers are commonly occurring cancers in women with very limited treatment options for relapse and metastasis. While immune checkpoint inhibitors have generated unprecedented responses in certain other cancer types, results from early attempts in ovarian and endometrial cancers have been suboptimal. To develop a CAR-T therapy against these cancers, multi-omics data mining identified ALPP (alkaline phosphatase, placental), a cell surface protein with expression restricted to female reproductive tissues, as a potential target. To validate its tumor-specific expression, immunohistochemical arrays were performed to assess cell surface display of ALPP in normal and cancerous tissues. An anti-ALPP CAR (TC-A101) was developed and validated for its targeting specificity against multiple ALP homologs, as well as its killing efficacy in vitro. The pre-clinical efficacy of this CAR was validated in an animal model of ovarian cancer peritoneal metastasis. A phase I clinical trial of TC-A101 for recurring and metastatic ovarian and endometrial cancer treatment was initiated to evaluate the safety, maximum tolerated dose, and clinical efficacy of this anti-ALPP CAR-T. Preclinical models demonstrate that TC-A101 T cell administration significantly reduces tumor burdens and extends the survival of mice bearing metastatic SiHa tumors and ascites. Three patients have been treated with low dose of TC-A101 without cytokine release syndrome manifestation or any other CAR-T related adverse events. We observed objective tumor regression in two of these three patients, with one patient reaching the threshold of partial response. The preclinical and initial clinical findings reported here indicate that TC-A101 T cell immunotherapy is safe and potentially efficacious against female reproductive cancers expressing ALPP.

Retro-inversion follicle-stimulating hormone peptide-modified nanoparticles for delivery of PDK2 shRNA against chemoresistant ovarian cancer by switching glycolysis to oxidative phosphorylation

BackgroundMost ovarian cancers are diagnosed at advanced stages characterized by abdominal dissemination and frequently exhibit chemoresistance. Pyruvate dehydrogenase kinase 2 (PDK2) regulates the switch between glycolysis and oxidative phosphorylation and contributes to tumor progression and chemoresistance. Here, we investigated the effects of PDK2 blockade on metabolic reprogramming and cisplatin sensitivity and evaluated the in vivo antitumor effects of PDK2 shRNA in chemoresistant ovarian cancer using retro-inverso follicle-stimulating hormone peptide-modified nanoparticle as carriers.MethodsThe expression of PDK2 was detected by immunohistochemistry, Western blot and real-time PCR. Cell proliferation and apoptosis were detected using CCK-8 and flow cytometry. Cell migration was detected by Transwell assay. Seahorse Analyzer was used to evaluate metabolic changes. The cisplatin-resistant ovarian cancer cells A2780cp were used to establish the mouse model of peritoneal metastatic ovarian cancer.ResultsA higher expression level of PDK2 was observed in chemoresistant ovarian cancer tissues and cell lines and was associated with shorter progression-free survival. PDK2 knockdown inhibited proliferation and migration and promoted apoptosis of both cisplatin-sensitive and cisplatin-resistant ovarian cancer cells. Cisplatin sensitivity was increased even in cisplatin-resistant ovarian cancer cells. Mechanistically, PDK2 knockdown resulted in an increased oxygen consumption rate and decreased extracellular acidification rate, along with reduced lactate production, increased PDHC activity and increased levels of electron transport chain complexes III and V. The metabolism switched from glycolysis to oxidative phosphorylation. Finally, to specifically and effectively deliver PDK2 shRNA in vivo, we formulated a targeted delivery system containing retro-inverso follicle-stimulating hormone peptide as a targeting moiety and polyethylene glycol–polyethylenimine copolymers as carriers. The nanoparticle complex significantly suppressed tumor growth and peritoneal metastasis of cisplatin-resistant ovarian cancer without obvious toxicities.ConclusionsOur findings showed the link between metabolic reprogramming and chemoresistance in ovarian cancer and provided an effective targeting strategy for switching metabolic pathways in cancer therapy.

Establishment of a piglet model for peritoneal metastasis of ovarian cancer

BackgroundA piglet model for peritoneal metastasis (PM) of ovarian cancer was developed. It will contribute to establishing innovative chemotherapeutical and surgical strategies without any limitation on rodent models.MethodsA total of 12 four- to five-week-old piglets of 7 to 8 kg were used. Two phases of ovarian cancer cell injections were performed with laparoscopic surgery.In phase I trial, 5.0 × 106 SK-OV-3 cells in 0.1 ml suspension were inoculated into the omentum, peritoneum, and uterine horns of two piglets twice with a one-week interval. In the phase II trial, 5.0 × 106 SNU-008 cells in 0.1 ml suspension were injected only into uterine horns within the same time frame because tumor implantation after inoculation of SK-OV-3 cells was not observed at the omentum or peritoneum in the phase I trial. Modified peritoneal cancer index (PCI) score was used to monitor tumorigenesis up to 4 weeks after inoculation. Tumor tissues disseminated in the peritoneum 4 weeks after injection were used for histological examination with hematoxylin and eosin (H&E) and paired-box gene 8 (PAX-8) staining.ResultsIn the phase I trial, two piglets showed PM with modified PCI scores of 5 and 4 at 3 weeks after the first inoculation, which increased to 14 and 15 after 4 weeks, respectively. In the phase II trial, PM was detected in eight of ten piglets, which showed modified PCI scores of 6 to 12 at 4 weeks after the first inoculation. The overall incidence of PM from the total of 12 piglets after inoculation was 75%. Immunohistochemical H&E and PAX-8 staining confirmed metastatic tumors.ConclusionsThis study provides strong evidence that piglets can be employed as a model for PM by inoculating ovarian cancer cell lines from humans. Using two cell lines, the PM rate is 75%.

ALCAM/CD166 Is Involved in the Binding and Uptake of Cancer-Derived Extracellular Vesicles.

Colorectal cancer (CRC) and ovarian cancer (OvC) patients frequently develop peritoneal metastasis, a condition associated with a very poor prognosis. In these cancers, tumor-derived extracellular vesicles (EVs) cause immunosuppression, facilitate the direct attachment and invasion of cancer cells through the mesothelium, induce the conversion of peritoneal mesothelial cells (PMCs) into cancer-associated fibroblasts (CAFs) and transfer a more aggressive phenotype amongst cancer cells. Although the promoting role of EVs in CRC and OvC peritoneal metastasis is well established, the specific molecules that mediate the interactions between tumor-derived EVs and immune and non-immune target cells remain elusive. Here, we employed the SKOV-3 (ovarian adenocarcinoma) and Colo-320 (colorectal adenocarcinoma) human cell lines as model systems to study the interactions and uptake of EVs produced by ovarian carcinoma and colorectal carcinoma cells, respectively. We established that the adhesion molecule ALCAM/CD166 is involved in the interaction of cancer-derived EVs with recipient cancer cells (a process termed “EV binding” or “EV docking”) and in their subsequent uptake by these cells. The identification of ALCAM/CD166 as a molecule mediating the docking and uptake of CRC and OvC-derived EVs may be potentially exploited to block the peritoneal metastasis cascade promoted by EVs in CRC and OvC patients.

Synergy between the Levels of Methylation of microRNA Gene Sets in Primary Tumors and Metastases of Ovarian Cancer Patients.

We studied the correlations between the levels of methylation of a group of 21 microRNA genes in 99 primary tumors and 29 macroscopic peritoneal metastases of ovarian cancer. Analysis of the level of methylation by quantitative methylation-specific PCR showed that co-methylation was detected for 13 pairs of microRNA genes in primary tumors and for 22 pairs in metastases. Pairs of microRNA genes that have shown significant co-methylation can be involved in common processes and pathways of gene regulation and interaction and can have common target genes. The results are highly significant and pairs of microRNA genes can be proposed as new potential markers for the diagnosis and prognosis of ovarian cancer metastasis.

MPEG-PDLLA Micelles Potentiate Docetaxel for Intraperitoneal Chemotherapy in Ovarian Cancer Peritoneal Metastasis.

Ovarian cancer is the second most common cause of gynecological cancer death in women. It is usually diagnosed late and accompanied by peritoneal metastasis. For ovarian cancer with peritoneal metastasis, intraperitoneal (IP) chemotherapy can maintain a high drug concentration in the abdominal cavity and reduce local and systemic toxicity. Recently, docetaxel (DTX) has shown broad-spectrum antitumor activity against various malignant tumors, including ovarian cancer with peritoneal metastasis. However, DTX has limited clinical applications due to its poor water solubility, predisposition to hypersensitivity, fluid retention, and varying degrees of neurotoxicity. In this study, we prepared methoxy-poly(ethylene glycol)-block-poly(D,L-lactide) (mPEG-PDLLA) micelles loaded with DTX and developed an alternative, less toxic, more effective DTX formulation, without Tween 80, and evaluated its pharmacokinetics in the abdominal cavity and its efficacy in ovarian cancer with peritoneal metastasis. The mean diameter of DTX-mPEG-PDLLA was about 25 nm, and the pharmacokinetics of BALB/c mice via IP showed that the plasma exposure of DTX-mPEG-PDLLA was about four times lower than that of DTX. Importantly, DTX-mPEG-PDLLA was significantly more effective than DTX and prolonged the survival period in a SKOV-3 ovarian cancer peritoneal metastasis model. Moreover, the apoptosis rate was significantly increased in vitro. Based on these findings, it is expected that DTX-mPEG-PDLLA can enhance efficacy against ovarian cancer peritoneal metastasis, while reducing toxic side effects, and has the potential to be used in the clinical treatment of peritoneal metastatic cancer.

Value of 3T diffusion weighted MRI in comparison with CECT in detection of ovarian cancer and ovarian cancer recurrence

Purpose: To investigate the value of 3T diffusion weighted magnetic resonance imaging (DW-MRI) compared to contrast enhanced computed tomography (CECT), in the preoperative staging of patients with suspected ovarian cancer (OC) or with suspected recurrence of ovarian cancer (ROC). Materials and methods: Thirty-two women (mean age 65 ± 14) with suspected (n = 23) or recurrent (n = 9) ovarian cancer were included prospectively in a single center study. CECT and abdominal 3T DW-MRI were performed. Both methods were used to independently score the presence of 1) ovarian tumor, 2) peritoneal or omental carcinomatosis, 3) pathological lymph nodes (LN), along with 4) liver parenchymal, 5) liver capsular, 6) diaphragmatic, and 7) extra-abdominal metastases. Findings were scored as: 0=benign, 1=suspicious for malignancy, or 2=definitely malignant. In addition, the lowest ADC values were measured in existing primary tumors. The extent of disease burden and correlation to histopathological findings were analyzed. Results: The mean disease score was higher in DW-MRI than in CT (4.9 ± 2.6 vs. 3.5 ± 2.2, P &lt; 0.001). Compared to CT, DW-MRI depicted more LN (P = 0.001) and diaphragmatic (P = 0.024) lesions. The lowest ADC values were significantly lower in malignant tumors (n = 18) than in benign tumors (n = 5) (0.640 x10-3mm2 /s ± 159 vs. 0.992 x10-3mm2 /s ± 218, P = 0.002). Conclusion: The results of our prospective single center study show incremental value of abdominal 3T DW-MRI in comparison with CECT, especially in detecting diaphragmatic and peritoneal ovarian cancer metastases, excluding lymph nodal metastases and in differentiating malignant adnexal tumors from benign.

Mesothelial-to-Mesenchymal Transition and Exosomes in Peritoneal Metastasis of Ovarian Cancer.

Most patients with ovarian cancer (OvCA) present peritoneal disseminated disease at the time of diagnosis. During peritoneal metastasis, cancer cells detach from the primary tumor and disseminate through the intraperitoneal fluid. The peritoneal mesothelial cell (PMC) monolayer that lines the abdominal cavity is the first barrier encountered by OvCA cells. Subsequent progression of tumors through the peritoneum leads to the accumulation into the peritoneal stroma of a sizeable population of carcinoma-associated fibroblasts (CAFs), which is mainly originated from a mesothelial-to-mesenchymal transition (MMT) process. A common characteristic of OvCA patients is the intraperitoneal accumulation of ascitic fluid, which is composed of cytokines, chemokines, growth factors, miRNAs, and proteins contained in exosomes, as well as tumor and mesothelial suspended cells, among other components that vary in proportion between patients. Exosomes are small extracellular vesicles that have been shown to mediate peritoneal metastasis by educating a pre-metastatic niche, promoting the accumulation of CAFs via MMT, and inducing tumor growth and chemoresistance. This review summarizes and discusses the pivotal role of exosomes and MMT as mediators of OvCA peritoneal colonization and as emerging diagnostic and therapeutic targets.

Epigenetic Silencing of miR-33b Promotes Peritoneal Metastases of Ovarian Cancer by Modulating the TAK1/FASN/CPT1A/NF-κB Axis.

Simple SummaryOmental metastasis and peritoneal dissemination are frequently observed in ovarian cancer peritoneal metastases and are associated with high mortality and poor prognosis. The tumor microenvironment is known to influence cancer epigenomics, which plays an essential role in promoting tumor development and metastatic progression. Therefore, investigation of the epigenetic mechanisms underlying the growth of ovarian cancer cells in the omental metastatic microenvironment is of great importance. Here, we report that miR-33b is significantly silenced by DNA hypermethylation in metastatic ovarian cancer cells to adapt to a lipid-rich microenvironment. Restoration of miR-33b was shown to impair lipid metabolic activities and reduce the oncogenic properties of ovarian cancer cells by negatively regulating the TAK1/FASN/CPT1A/NF-κB pathway, indicating that targeting this signaling cascade may be a molecular therapeutic choice for ovarian cancer metastatic progression.Peritoneal metastases are frequently found in high-grade serous carcinoma (HGSOC) patients and are commonly associated with a poor prognosis. The tumor microenvironment (TME) is a complex milieu that plays a critical role in epigenetic alterations driving tumor development and metastatic progression. However, the impact of epigenetic alterations on metastatic ovarian cancer cells in the harsh peritoneal microenvironment remains incompletely understood. Here, we identified that miR-33b is frequently silenced by promoter hypermethylation in HGSOC cells derived from metastatic omental tumor tissues. Enforced expression of miR-33b abrogates the oncogenic properties of ovarian cancer cells cocultured in omental conditioned medium (OCM), which mimics the ascites microenvironment, and in vivo tumor growth. Of note, restoration of miR-33b inhibited OCM-upregulated de novo lipogenesis and fatty acid β-oxidation in ovarian cancer cells, indicating that miR-33b may play a novel tumor suppressor role in the lipid-mediated oncogenic properties of metastatic ovarian cancer cells found in the omentum. Mechanistic studies demonstrated that miR-33b directly targets transforming growth factor beta-activated kinase 1 (TAK1), thereby suppressing the activities of fatty acid synthase (FASN) and carnitine palmitoyltransferase 1A (CPT1A) in modulating lipid metabolic activities and simultaneously inhibiting the phosphorylation of NF-κB signaling to govern the oncogenic behaviors of ovarian cancer cells. Thus, our data suggest that a lipid-rich microenvironment may cause epigenetic silencing of miR-33b, which negatively modulates ovarian cancer peritoneal metastases, at least in part, by suppressing TAK1/FASN/CPT1A/NF-κB signaling.

The Stress-Inducible BCL2A1 Is Required for Ovarian Cancer Metastatic Progression in the Peritoneal Microenvironment.

Simple SummaryCancer metastasis is still the main cause of cancer-related mortality. Peritoneal metastases are the first presentation of advanced ovarian cancer, and metastatic cancer cells tend to disseminate trans-peritoneally in the peritoneal cavity. Hypoxia is a critical factor in governing transcoelomic metastases of ovarian cancer. Therefore, targeting hypoxia appears to be a promising approach to arrest cancer metastasis. In the present work, we identified that BCL2A1, a BCL2 family member, is significantly induced by hypoxia and other physiological stresses by NF-κB signaling and followed by a gradual degradation. The upregulated BLC2A1 has been shown to enhance ovarian cancer survival, tumor growth, and tumor dissemination by suppressing intrinsic cell apoptosis. These data indicate BCL2A1 is an early response factor in the stressed tumor microenvironment, and targeting BCL2A1 may be a potential therapeutic approach in eradicating peritoneal metastases of ovarian cancer.Emerging evidence indicates that hypoxia plays a critical role in governing the transcoelomic metastasis of ovarian cancer. Hence, targeting hypoxia may be a promising approach to prevent the metastasis of ovarian cancer. Here, we report that BCL2A1, a BCL2 family member, acts as a hypoxia-inducible gene for promoting tumor progression in ovarian cancer peritoneal metastases. We demonstrated that BCL2A1 was induced not only by hypoxia but also other physiological stresses through NF-κB signaling and then was gradually reduced by the ubiquitin-proteasome pathway in ascites-derived ovarian cancer cells. The upregulated BCL2A1 was frequently found in advanced metastatic ovarian cancer cells, suggesting its clinical relevance in ovarian cancer metastatic progression. Functionally, BCL2A1 enhanced the foci formation ability of ovarian cancer cells in a stress-conditioned medium, colony formation in an ex vivo omental tumor model, and tumor dissemination in vivo. Under stress conditions, BCL2A1 accumulated and colocalized with mitochondria to suppress intrinsic cell apoptosis by interacting with the BH3-only subfamily BCL2 members HRK/BAD/BID in ovarian cancer cells. These findings indicate that BCL2A1 is an early response factor that maintains the survival of ovarian cancer cells in the harsh tumor microenvironment.