Serous Cells Research Articles

Characteristics of Extracellular Vesicles from a High-Grade Serous Ovarian Cancer Cell Line Derived from a Platinum-Resistant Patient as a Potential Tool for Aiding the Prediction of Responses to Chemotherapy.

Platinum-resistant high-grade serous ovarian cancer (HGSOC) is invariably a fatal disease. A central goal of ovarian cancer research is therefore to develop new strategies to overcome platinum resistance. Treatment is thus moving towards personalized therapy. However, validated molecular biomarkers that predict patients' risk of developing platinum resistance are still lacking. Extracellular vesicles (EVs) are promising candidate biomarkers. EpCAM-specific EVs are largely unexplored biomarkers for predicting chemoresistance. Using transmission electron microscopy, nanoparticle tracking analysis and flow cytometry, we compared the characteristics of EVs released from a cell line derived from a clinically confirmed cisplatin-resistant patient (OAW28) and EVs released from two cell lines from tumors sensitive to platinum-based chemotherapy (PEO1 and OAW42). We demonstrated that EVs released from the HGSOC cell line of chemoresistant patients exhibited greater size heterogeneity, a larger proportion of medium/large (>200 nm) Evs and a higher number of released EpCAM-positive EVs of different sizes, although the expression of EpCAM was predominant in EVs larger than 400 nm. We also found a strong positive correlation between the concentration of EpCAM-positive EVs and the expression of cellular EpCAM. These results may contribute to the prediction of platinum resistance in the future, although they should first be validated in clinical samples.

CDK2 regulates collapsed replication fork repair in CCNE1-amplified ovarian cancer cells via homologous recombination.

CCNE1 amplification is a common alteration in high-grade serous ovarian cancer and occurs in 15-20% of these tumors. These amplifications are mutually exclusive with homologous recombination deficiency, and, as they have intact homologous recombination, are intrinsically resistant to poly (ADP-ribose) polymerase inhibitors or chemotherapy agents. Understanding the molecular mechanisms that lead to this mutual exclusivity may reveal therapeutic vulnerabilities that could be leveraged in the clinic in this still underserved patient population. Here, we demonstrate that CCNE1-amplified high-grade serous ovarian cancer cells rely on homologous recombination to repair collapsed replication forks. Cyclin-dependent kinase 2, the canonical partner of cyclin E1, uniquely regulates homologous recombination in this genetic context, and as such cyclin-dependent kinase 2 inhibition synergizes with DNA damaging agents in vitro and in vivo. We demonstrate that combining a selective cyclin-dependent kinase 2 inhibitor with a DNA damaging agent could be a powerful tool in the clinic for high-grade serous ovarian cancer.

Preclinical testing of farletuzumab ecteribulin (FZEC [MORAb-202]) and MORAb-109, folate receptor α and mesothelin targeting antibody-drug conjugates (ADCs), in rare gynecologic cancers.

e17634 Background: Rare gynecologic cancers, such as ovarian carcinosarcoma (OCS), uterine serous carcinoma (USC) and ovarian clear cell adenocarcinoma (OCCA), have limited treatment options and molecular alterations that drive cell proliferation and drug resistance, resulting in poor overall survival. The anti-microtubule agent (AMA) paclitaxel is used in first-line treatment of most gynecologic cancers; however, the AMA eribulin is known to have additional anticancer properties (Goto et al. Anticancer Res 38:2929, 2018; Ho et al. Cancer Res 82:4457, 2022). Eribulin ADCs have been developed for targeted delivery to limit toxicity and maximize response. FZEC is an anti-folate receptor α (FRA)-eribulin ADC (Shimizu et al. Clin Cancer Res 27:3905, 2021) and MORAb-109 targets eribulin to mesothelin (MSLN; Albone et al. Annals Oncol 31:S491, 2020). Here we provide preclinical data to support clinical trials of FZEC and MORAb-109 in rare gynecologic cancers. Methods: Fresh tumor tissue from patients consented to the WEHI Stafford Fox Rare Cancer Program was used to establish a cohort of patient-derived xenograft (PDX) models of high-grade serous ovarian carcinoma (HGSOC), OCS, USC and OCCA. PDX models were screened for FRA and MSLN expression by IHC and quantified by HALO software, and 15 models were selected for in vivo testing. Tumor-bearing mice were treated with eribulin (1 mg/kg TIW 3 wks), FZEC (12.5 mg/kg Q14Dx3) or MORAb-109 (25 mg/kg Q14Dx3) and compared to standard of care treatments. Results: About 80% of HGSOC PDX models were FRA positive with no difference between models from chemonaïve samples vs multiple lines of prior treatment. FRA expression was frequent in USC and OCCA models, with MSLN seen in a smaller subset. Despite most (80%) models being cisplatin refractory, 11/15 responded to eribulin with the 4 non-responders having high MDR1 expression and being from previously treated patients. Overall, responses to FZEC and MORAb-109 appeared to correlate with FRA and MSLN expression; importantly, some models with moderate to high target antigen expression showed deeper and more durable responses to FZEC and MORAb-109 compared to eribulin. Conclusions: Responses to FZEC and MORAb-109 correlated with FRA and MSLN expression, with equivalent or better activity compared to eribulin in target-positive PDX models of HGSOC, USC and OCCA. [Table: see text]

Preliminary results of a phase II trial with sacituzumab govitecan-hziy in patients with recurrent endometrial carcinoma overexpressing Trop-2.

5599 Background: Despite recent advances, there remains a significant need for targeted, efficacious treatments for advanced and recurrent endometrial carcinoma (EC). Trop-2 has been demonstrated to be overexpressed in several EC including grade 3 endometrioid adenocarcinoma (96%), and uterine serous carcinoma (65%). Trop-2 overexpression has been found to confer a worse prognosis and predicts disease recurrence. Sacituzumab govitecan-hziy (SG) is an antibody-drug conjugate comprised of a humanized anti-Trop-2 antibody conjugated with the active metabolite of irinotecan, a topoisomerase-I inhibitor. SG is currently FDA-approved for use in metastatic urothelial cancer and metastatic triple-negative breast cancer. Methods: We report results from the stage 1 of an open-label non-randomized phase 2 trial (NCT04251416) established to evaluate the clinical activity of SG in patients with persistent or recurrent EC of epithelial origin with Trop-2 overexpression. Criteria for study participation included radiographically confirmed and measurable persistent or recurrent EC, progression after or during platinum-based chemotherapy, and at least 2+ staining of Trop-2. One target lesion by RECIST v1.1 and adequate bone marrow, renal, and hepatic function were required. Patients were at least two weeks beyond prior treatment, major surgery, or high dose systemic corticosteroid use. Patients were given 10mg/kg of SG administered as an intravenous infusion once weekly on days 1 and 8 of 21-day treatment cycles. This 3-week cycle was continued without rest until disease progression or unacceptable toxicity. Results: Twenty-one patients were enrolled into stage 1. Ten patients (48%) had uterine serous carcinoma, seven (33%) had endometrioid adenocarcinoma, three (14%) had carcinosarcoma, and one patient had mixed serous and clear cell histology. All patients received at least one prior line of chemotherapy, (median 3 lines, range 1-6). At the time of submission, 20 patients were response-evaluable (Table); seven (35%) achieved objective response (5 out of 7 confirmed). Eighteen patients were evaluable for durable disease control; 7 (39%) achieved it. Follow-up durations had a median (IQR) of 15.6 (5.7–22.5) months. Median OS was 22.5 months, and median PFS was 5.7 months. The treatment was well-tolerated with no new or unexpected safety signals reported. Conclusions: Sacituzumab govitecan shows remarkable clinical activity against some of the most historically challenging and chemotherapy-resistant endometrial pathologies and demonstrates a favorable safety profile. With these promising results, we will begin the stage 2 expansion of this phase 2 trial. Clinical trial information: NCT04251416 . [Table: see text]

Structural Features of the Cardia Gastric Region in Domestic Rabbits

The knowledge of normal microscopical peculiarities of the digestive system in mammals is essential, but information regarding certain structures is still scarce in numerous species. Our study aims to highlight the normal morphological features of the cardia region in domestic rabbits, as regards the overall appearance, structure, and dimensions of the gastric pits, including a description of the cells located in gastric glands. The cardia region of five domestic rabbits underwent tissue sampling, followed by fixation in 10% buffered formalin, paraffin embedding, and later sectioned at 5 µm in thickness. Eventually, the samples were stained by Goldner’s trichrome method. The microscopical examination has revealed the presence of gastric pits and glands in the entire cardia region of the rabbit, with a different morphological appearance from one zone to another. Gastric pits have the smallest depth immediately after the oesophagogastric junction, which gradually increases and decreases afterwards as it approaches the fundic zone. The gastric glands contain basically four cell types in various proportions, including serous cells, mucous cells, parietal cells, and chief cells. Other peculiarities of the gastric mucosa in the cardia region in rabbits include a thick mucosa with a loose and prominent lamina propria, and an ill-defined muscularis mucosae that is not organized in distinct layers as in other species. The detailed microanatomical structure of the cardia region of the stomach is necessary for understanding the digestion processes in rabbits, species used as a model in diverse fields of research including the pathology of the digestive system.

Microsatellite instability in non-endometrioid ovarian epithelial tumors: a study of 400 cases comparing immunohistochemistry, PCR, and NGS based testing with mutation status of MMR genes

Testing of microsatellite instability is not only used as a triage for possible Lynch syndrome, but also to predict immunotherapy treatment response. The aim of this study was to assess the frequency of mismatch repair deficiency (MMR-D) / microsatellite instability (MSI) in 400 cases of non-endometrioid ovarian tumors (high-grade serous, low-grade serous, mucinous and clear cell), to compare different methodological approaches of testing, and to assess the optimal approach for next generation sequencing (NGS) MSI testing. For all tumors, we evaluated immunohistochemical (IHC) expression of MMR proteins and assessed microsatellite markers by PCR-based method. Except for high-grade serous carcinoma, we correlated the findings of IHC and PCR with NGS-based MSI testing. We compared the results with somatic and germline mutation in MMR genes. Among the whole cohort, seven MMR-D cases, all clear cell carcinomas (CCC), were found. On PCR analysis, six cases were MSI-high and one was MSS. In all cases, mutation of an MMR gene was found; in two cases, the mutation was germline (Lynch syndrome). An additional five cases with a mutation in MMR gene(s) with MSS status and without MMR-D were identified. We further utilized sequence capture NGS for MSI testing. Employing 53 microsatellite loci provided high sensitivity and specificity. Our study shows that MSI occurs in 7% of CCC while it is rare or absent in other non-endometrioid ovarian neoplasms. Lynch syndrome was present in 2% of patients with CCC. However, some cases with MSH6 mutation can evade all testing methods, including IHC, PCR, and NGS-MSI.

Characterization of ZG16b protein exocrine function and biomarker potential for salivary gland damage in chronic graft vs. host disease

Abstract The oral cavity is a frequent target of chronic Graft versus Host Disease (cGVHD) following allogenic hematopoietic stem cell transplant (allo-HSCT). Detection of early cGVHD-induced damage to exocrine tissues, such as salivary glands, is challenging to detect prior to irreversible tissue fibrosis. Recent work in our laboratory used shotgun proteomics to identify putative salivary biomarkers at salivary gland cGVHD onset. Saliva samples from patients affected with oral cGVHD post allo-HSCT had a drop in protein content of zymogen granule 16b (ZG16b), recapitulated in immunohistochemical staining of human minor salivary gland (MSG) biopsy sections. ZG16b loss correlated with CD45+ cells infiltration. This protein is poorly characterized, and immunofluorescence tissue staining suggested ZG16b protein localization to acinar cells. ZG16b cellular expression localized to serous and serous mucous acinar cell populations in single cell RNAseq (scRNA seq) data from healthy human labial MSG. Little is known about the function of this ZG16b in other exocrine tissues such as pancreas. scRNA seq analysis of repository data suggests ZG16b colonization in the pancreatic ductal cells. Similar to MSG, the pancreatic Zg16b gene was expressed in mucus secretion pathways and additional interactions with cell migration and homeostasis markers. Ongoing work is being done to further probe for binding partners for ZG16b (endogenous proteins, components of the oral microbiome and immune cell receptors) to distinguish the protein from its homologs. In parallel, the utility of salivary ZG16b as a cGVHD and general salivary gland damage biomarker is being tested. This work will bring clarity Zg16b’s role in exocrine tissues and alloimmune disease. NIH, NIDCR Intramural program

Water and heat exchanges in mammalian lungs

A secondary function of the respiratory system of the mammals is, during inspiration, to heat the air to body temperature and to saturate it with water before it reaches the alveoli. Relying on a mathematical model, we propose a comprehensive analysis of this function, considering all the terrestrial mammals (spanning six orders of magnitude of the body mass, M) and focusing on the sole contribution of the lungs to this air conditioning. The results highlight significant differences between the small and the large mammals, as well as between rest and effort, regarding the spatial distribution of heat and water exchanges in the lungs, and also in terms of regime of mass transfer taking place in the lumen of the airways. Interestingly, the results show that the mammalian lungs appear to be designed just right to fully condition the air at maximal effort (and clearly over-designed at rest, except for the smallest mammals): all generations of the bronchial region of the lungs are mobilized for this purpose, with calculated values of the local evaporation rate of water from the bronchial mucosa that can be very close to the maximal ability of the serous cells to replenish this mucosa with water. For mammals with a mass above a certain threshold (simeq 5 kg at rest and simeq 50 g at maximal effort), it appears that the maximal value of this evaporation rate scales as M^{-1/8} at rest and M^{-1/16} at maximal effort and that around 40% (at rest) or 50% (at maximal effort) of the water/heat extracted from the lungs during inspiration is returned to the bronchial mucosa during expiration, independently of the mass, due to a subtle coupling between different phenomena. This last result implies that, above these thresholds, the amounts of water and heat extracted from the lungs by the ventilation scale with the mass such as the ventilation rate does (i.e. as M^{3/4} at rest and M^{7/8} at maximal effort). Finally, it is worth to mention that these amounts appear to remain limited, but not negligible, when compared to relevant global quantities, even at maximal effort (4–6%).

Frequencies, clinicopathological features, and risk factors of type I and type II endometrial cancer; a retrospective observational study at a tertiary care hospital in Pakistan

Background: Endometrial cancer (EC) is the most common gynecological malignancy worldwide. The death rates for EC have increased by more than 100% over the past 2 decades. EC is subdivided into two types based on distinct histological and clinical features: type I and type II. Our study aims to determine the risk factors and clinicopathological features of both type I and type II EC and draw a comparison between the two types based on frequency, risk factors and clinicopathological features. Methods: It was a retrospective observational study including patients of a single tertiary care center. The study included Patients diagnosed, treated, and followed up for type I and type II endometrial cancer at the study center over the past 19 years from 1st January 2000 to 31st December 2018. All the patients with metastatic endometrial cancer were excluded from the study. SPSS version 26 was used for statistical analysis. Results: A total of 376 patients were included in this study. Among these 343 (91.7) patients had endometroid adenocarcinoma (Type I) and 32 (8.3) had serous and clear cell tumor (type II). Type I EC had a mean age of 57.56 (SD±10.42) while patients with type II EC presented with a mean age of64.97 (SD±6.59). Hypertension and Diabetes were the most common comorbid in EC patients. HRT prior to EC was found to have an association with risk of EC. Compared to patients who were on HRT, patients who were not on HRT prior to diagnosis of EC had 80% less chance of developing endometrial cancer. (Confidence interval: 0.056-0.114, p=0.016). Conclusions: In summary our study demonstrates that both sub types of endometrial cancer have many risk factors that are similar to each other. Despite the difference between the population of both subgroups we were able to prove associations between risk factors and endometrial cancer. However further research is needed at provincial and national level with larger and relatively comparable sample sizes for both subgroups to recognize risk factors and numerically associate them to EC for Pakistani population.

Abstract LB039: Ovarian cancer cell-derived exosomal UCA1 reprograms glucose metabolism in stromal fibroblasts

Abstract Tumor progression is stringently regulated by the co-ordinated signaling between the tumor cells and the tumor microenvironment (TME) through diverse autocrine, paracrine and exocrine signaling mechanisms. Recent studies have shown that the exosomes that play a crucial role in the transfer of oncogenic macromolecules and oncometabolites to different cellular components of the TME can be targeted for therapy. Therefore, with the focus on identifying the exosomal long non-coding RNA (lncRNA) that can be therapeutically targeted, we investigated the profile of ovarian cancer cell derived lncRNAs and their functional role in ovarian cancer pathophysiology. Analysis of exosomes derived from a panel of high grade serous ovarian cancer cell lines indicated that UCA1 (Urothelial Cancer Associated 1) is the most abundantly packaged lncRNA in the exosomes. Similarly, exosomes from patient-derived ovarian cancer cells exhibited higher levels of UCA1. Ascites from ovarian cancer patients also indicated high levels of UCA1 in the ascites-derived exosomes. Results using PKH67-labelled ovarian cancer cell-derived exosomes and MRC5 fibroblast cell line indicated the exosomal transfer of UCA1 to the fibroblasts. Since paracrine signaling has been shown to induce metabolic reprogramming of peritumoral fibroblasts, we interrogated whether exosomal transfer of UCA1 could reprogram the glucose metabolism in the fibroblasts. Results from the Agilent Seahorse glycolytic stress assay indicate that the exosomal UCA1 promotes reprogramming of glucose metabolism in fibroblast cells while depleting of UCA1 in the exosomes failed to induce such metabolic reprogramming. Results from the analysis of the key glycolytic enzymes in the stromal fibroblasts, post-exosomal UCA1 uptake also corroborate this conclusion. Thus our results provide primary evidence that the exosomal-UCA1 induces pro-tumorigenic metabolic reprogramming in peri-tumoral fibroblasts. Together with the known oncogenic role of UCA1 in many different cancer cells, our findings indicate that targeting UCA1 could form a productive precision cancer strategy in ovarian cancer, targeting both the tumor cells and tumor stromal cells. This research was supported by the Department of Defense Ovarian Cancer Research Program Award W81XWH-18-1-0066, W81XWH-22-1-0415, the National Institute of General Medical Sciences grant P20 GM103639 and The National Cancer Institute of the National Institutes of Health grant P30 CA225520. Citation Format: Revathy Nadhan, Ji Hee Ha, Muralidharan Jayaraman, Srishti Kashyap, Danny N. Dhanasekaran. Ovarian cancer cell-derived exosomal UCA1 reprograms glucose metabolism in stromal fibroblasts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr LB039.

HISTOMORPHOLOGY OF PANCREATIC TISSUE IN MEDAKA FISH (Oryzias javanicus): STUDY OF DIABETIC ANIMAL MODEL DEVELOPMENT

This study aimed to explore the histomorphology of the pancreatic tissue of medaka fish to develop medaka fish as a diabetic animal model. Adult medaka fish were obtained with a body length of 2.53±0.22 cm and a weight of 265.8±25 g. Medaka fish were fixed using Boiun's fixative solution. Macro anatomical observations of the pancreas were conducted using a stereomicroscope. Histological preparations were made according to the Hematoxylin-eosin staining standard procedure. Pancreatic histomorphology of medaka fish was carried out using a light microscope with 100x and 400x magnification. The macro anatomy observations of the pancreas showed the interconnection with several tissues, such as spleen, gallbladder, liver, fat, and intestines. The pancreas was located toward the liver, oversees the intestines, and covered with fat. Pancreatic histomorphological observations showed exocrine cells composed of serous pyramidal acinar cells and endocrine cells (islets of Langerhans). Intralobular and intercalated ducts (ducts of Boll) were composed of simple cuboidal epithelium. This study concluded that the pancreas organ in medaka fish is a single organ, and histomorphologically has both of exocrine and endocrine cells.

Abstract 5512: TIC10/ONC201 in combination with ceralasertib exhibits potent synergy in high grade serous ovarian cancer cells

Abstract High-grade serous ovarian cancer (HGSOC) is the most common and malignant form of ovarian cancer. Although patients with HGSOC are likely to respond to treatment, it is common for the cancer to recur and become resistant to treatment, therefore there is a need to develop new targets and novel combinations to increase patient survival rates. ATRi’s (Ataxia telangiectasia and Rad3 related inhibitors) have shown efficacy in HGSOC. Considering ATRi’s have shown moderate efficacy as a single treatment in HGSOC patients, we hypothesized that combining ATRi’s with ONC201 would enhance efficacy. ONC201 is a pro-apoptotic TRAIL-inducing compound that activates the integrated stress response and inactivates the Akt pathway which is upregulated in over 70% of HGSOC. Inactivation of the Akt pathway may result in a synergistic effect that could be translated for use in patients with HGSOC. Three HGSOC cell lines were treated with the novel drug combination of ceralasertib (ATRi) and ONC201 and CellTiterGLO viability assays were performed after 72 hours to evaluate the synergistic effect of combination treatment. Western blots were performed to investigate the synergistic effect of combination treatment on the Akt pathway as well as expression of the cellular metabolic stress protein ATF4. Cytokine profiling using the Luminex 200 technology was performed to study treatment-induced changes in the tumor microenvironment. Cell viability after ceralasertib and ONC201 combination treatment showed synergy in HGSOC cell lines (OVCAR3, KURAMOCHI, TOV21G). In TOV21G cell line, combination studies of ONC201 and ceralasertib calculated by compusyn software demonstrated a synergistic effect of both drugs, Combination indexes below one were observed at concentration of 0.008-2 μM of ceralasertib with 0.31-5 μM of ONC201 with the best combination index of 0.65. We similarly observed synergy in the two other cell line between ONC201 and ceralasertib. Western blotting showed reduction in total Akt and Erk expression and an increase in ATF4, consistent with the observed synergetic effect of ceralasertib and ONC201 combination. Our ongoing studies are exploring potential mechanisms of synergy between ceralasertib and ONC201 and effects on immune–mediated killing of HGSOC cells. Our results suggest a rational and potentially effective novel therapy combination of ATRi ceralasertib and ONC201 that maybe further developed for HGSOC. Citation Format: Maryam Ghandali, Kadir Mert Selvi, Kelsey E. Huntington, Andrew George, Anna Ochsner, Benedito A. Carneiro, Donn S. Dizon, Wafik S. El-Deiry. TIC10/ONC201 in combination with ceralasertib exhibits potent synergy in high grade serous ovarian cancer cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5512.

Abstract 773: Early detection of ovarian cancer using cell-free DNA fragmentomes

Abstract Introduction: Ovarian cancer is the leading cause of death from gynecological related cancers worldwide. Most patients are diagnosed at late stages due to asymptomatic disease and lack of effective screening modalities. Additionally, in women with an ovarian mass the diagnosis of ovarian cancer can be challenging with many women having surgery only to discover a benign pathology. Liquid biopsies, including analyses of cell-free DNA (cfDNA) fragmentomes in the circulation, have shown promise for the early detection of cancer and may provide a useful avenue for detection of ovarian cancer. Methods: To evaluate cfDNA fragmentomes for detecting ovarian cancer, we assessed plasma from 507 women, including 128 with ovarian cancers comprising high grade serous, endometrioid, mucinous and clear cell subtypes, 48 with benign masses, and 223 without cancer, as well as a validation cohort of 108 women with (n=14) and without (n=94) ovarian cancers from a separate institution. We obtained cfDNA from each individual and performed low-coverage (1-2x) whole genome sequencing. The cfDNA fragmentome data were analyzed with our DELFI (DNA evaluation of fragments for early interception) approach optimized for high specificity. We used a cross-validated machine learning model, and the fixed DELFI model was evaluated in the external validation cohort. Results: Individuals with ovarian cancer had significantly higher DELFI scores than those without cancer (mean 0.59 vs 0.18, respectively, p < 0.0001) resulting in an AUC of 0.85 (95% CI = 0.80-0.90). DELFI was successful in identifying high-grade serous ovarian cancer across all stages, with sensitivities of 56%, 60%, 58% and 100% for stages I - IV, respectively, at 99% specificity. We further applied DELFI to evaluate women with ovarian masses in a prospective observational cohort (NL58253.031.16). Women with benign masses had DELFI scores lower than those with ovarian cancer (mean 0.23 vs 0.59, p< .0001) and were distinguished with an overall AUC of 0.80 (95% CI = 0.73-0.86). In the external validation cohort, women with cancer were distinguished from women without cancer with an AUC of 0.88 (95% CI = 0.72 - 1.0). At the DELFI score threshold with 99% specificity in the cross-validated cohort, the external validation cohort had specificity of 97% with an overall sensitivity of 79%. The cfDNA fragmentome profiles reflected chromosomal, chromatin, transcription factor binding site, and disease-specific pathway changes known to be altered in ovarian cancer. We are extending these efforts to over 1000 individuals with and without ovarian cancer and the integrated results will be presented. Conclusion: Overall, we demonstrate the utility of cfDNA fragmentomes for noninvasive detection of ovarian cancer. These results may provide a feasible approach for ovarian cancer screening and management of patients with ovarian masses. Citation Format: Akshaya V. Annapragada, Jamie E. Medina, Pien Lof, Dimitrios Mathios, Zachariah H. Foda, Michaël Noë, Sarah Short, Adrianna Bartolomucci, Daniel C. Bruhm, Euihye Jung, Jenna Canzoniero, Noushin Niknafs, Stephen Cristiano, Vilmos Adleff, Heather Symecko, Daan van de Broek, Stephen B. Baylin, Michael F. Press, Dennis Slamon, Gottfried Konecny, Susan Domchek, Ronny Drapkin, Jillian Phallen, Robert B. Scharpf, Christianne Lok, Victor E. Velculescu. Early detection of ovarian cancer using cell-free DNA fragmentomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 773.

Abstract 2440: HOTAIR functionality and regulation in ovarian cancer stem cells

Abstract Ovarian cancer (OC) is the fifth leading cause of cancer-related death among American women. Persistence of OC stem cells (OCSCs) is believed to contribute to resistance to platinum-based chemotherapy and disease relapse. We have previously shown that epigenetic changes in OCSCs play a role in post-therapy OCSC persistence and demonstrated the potential to target OCSC using epigenetic therapies. HOXC transcript antisense RNA (HOTAIR) has been shown to be associated with chemoresistance and overexpressed in high-grade serous OC (HGSOC). HOTAIR interacts with Polycomb Repressive Complex 2 (PRC2) and plays a key role in chromatin remodeling. Because HOTAIR is a known epigenetic regulator of differentiation and developmental genes in OC, we hypothesized that HOTAIR regulates OCSCs and epigenetic targeting HOTAIR will prevent tumor relapse. To produce loss-of-function phenotypes of HOTAIR and investigate the function of this gene, we utilized the paired CRISPR guide RNA design to delete the functional sites of HOTAIR in a panel high grade serous OC cell lines (Kuramochi, OVCAR3) without affecting nearby protein-coding gene. Knockout of HOTAIR re-sensitized OC cells to platinum treatment and significantly decreased (P<0.001) the OCSC population and stemness-related phenotypes, including inhibiting stemness-associated gene expression ALDH1A1, Notch3, Sox9, and PROM1 and in vitro spheroid forming ability under low attachment conditions. Integrated analysis of RNA-seq and ATAC-seq on control and HOTAIR knockout cells revealed HOTAIR altered global chromatin dynamics to change downstream gene expression, particularly, the NF-kB pathway. In xenograft assays using HGSOC cells, combining a HOTAIR inhibitor with an EZH2 inhibitor and chemotherapy significantly decreased in vivo tumor formation and increased mouse survival. In summary, depletion of HOTAIR functionally decreased OCSC phenotypes and malignant potential and reprogrammed HGSOC to a less stem-like phenotype. There is an urgent need to develop new therapeutic strategies to target OCSCs and overcome chemoresistant OC, and the results of this study suggest that targeting HOTAIR in combination with epigenetic therapies may represent a novel therapeutic strategy to prevent tumor relapse in OC. Citation Format: Weini Wang, Yanchi Zhou, Ji Wang, Ali Ozes, Heather M. O’Hagan, Anirban Mitra, Kenneth P. Nephew. HOTAIR functionality and regulation in ovarian cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2440.

Abstract 5804: Targeting methyl donor synthesis inhibits platinum-induced enrichment of ovarian cancer stem cells

Abstract Ovarian cancer (OC) is one of the deadliest gynecologic cancers in US. Platinum (Pt)-based chemotherapy can reprogram cancer cells to ovarian cancer stem cells (OCSCs) and contribute to incurable recurrence. We have previously shown that Pt-containing drugs, e.g., cisplatin, enrich for OCSCs and Pt-induced alterations in DNA methylation enhanced OCSC malignant properties. CSCs have been shown to be dependent on methionine (Met) in many cancers, and in the current study, we investigated the role of Met and the interplay between methylation and Met metabolism in OCSC enrichment. In high grade serous ovarian cancer cell lines (OVCAR5, OVCAR3), cisplatin treatment (IC50, 16hr) increased (p<0.01) the percentage of cells that were positive for aldehyde dehydrogenase (ALDH+ cells), a known OCSCs marker. Cisplatin treatment also increased (p<0.05) the whole cell level of 5-methylcytosine, indicating Pt-induced methylation changes. In addition, Met metabolism was altered by cisplatin, demonstrated by decreased (p<0.01) level of Met derivative, S-adenosyl-methionine (SAM), and increased (p<0.01) expression of Met utilization enzyme, methionine adenosyltransferase 2A (MAT2A). To investigate a possible role of Met metabolism in Pt-induced enrichment of OCSCs, OVCAR5 cells were cultured in complete or Met-depleted (Met-) media, treated with cisplatin or vehicle and examined for CSC properties, including ALDH+ cells and the ability to form spheroids under low-attachment conditions. Met depletion blocked (p<0.01) both the Pt-induced increase of ALDH+ cells and spheroid formation. Both Met- only and Met- in combination with cisplatin activated p38, determined by increased phosphorylated p38, which may have responded to Met depletion and promoted cell cycle arrest. In addition, MAT2A expression was higher (p<0.01) in ALDH+ compared to ALDH- OC cells. MAT2A inhibitor FIDAS-5 combined with cisplatin blocked the Pt-induced increase in ALDH+ cells (p<0.01), demonstrating a requirement for Met utilization in Pt-induced OCSC enrichment. As MAT2A is a therapeutic target in cancer, MAT2A inhibition could represent a therapeutic approach for inhibiting CSC in ovarian cancer. We are further investigating the mechanism of MAT2A-mediated inhibition on Pt-induced OCSCs enrichment by examining the OC methylome and cell cycle arrest. Citation Format: Shu Zhang, Tara X. Metcalfe, Christiane A. Hassel, Heather M. O'Hagan, Kenneth P. Nephew. Targeting methyl donor synthesis inhibits platinum-induced enrichment of ovarian cancer stem cells. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5804.

Abstract 2553: Elucidation of the downstream signaling of PIK3CA genomic alterations in serous ovarian cancer

Abstract Genomic aberrations of PIK3CA, which encodes the catalytic subunit p110α of the class IA phosphatidylinositol 3-kinase (PI3K), is frequently observed in cancers. In ovarian cancer of the serous subtype (the most common histotype of the disease), PIK3CA amplification is dominant over single nucleotide mutations in multiple patient cohorts, suggesting the possibility that PIK3CA amplification is an alternative to PIK3CA “hot spot” mutation for serous ovarian tumorigenesis. However, whether PIK3CA amplification and mutation exert the same functional consequences on serous ovarian tumorigenesis remains uncertain. This study aims to explore and compare the functional roles between the two types of PIK3CA gene aberrations on tumorigenicity, cellular signaling, and therapeutic responses in serous ovarian cancer. We confirmed that both PIK3CA amplification and E545K mutation could induce multiple tumorigenic phenotypes in CRISPR/Cas9-mediated E545K knock-in or wild-type PIK3CA overexpressing serous ovarian cancer cell lines. Signaling pathway analyses showed that E545K knock-in cells, but not PIK3CA-overexpressing cells, had the MAPK signaling pathway activated and were sensitive to MAPK pathway inhibition. An induction of AKT phosphorylation and PDK1 phosphorylation was observed in both E545K knock-in cells and wild-type PIK3CA-overexpressing cells. Accordingly, these cells displayed higher sensitivity towards p110α or AKT inhibitors. Intriguingly, in line with previous report which demonstrated YAP as AKT substrate, the activation of AKT associated with an increase in YAP S127 phosphorylation in the knock-in or PIK3CA-overexpressing cells. AKT inhibition suppressed YAP phosphorylation. Corroborating with the role of S127 in nuclear exclusion of YAP, YAP accumulated in the cytoplasm of these cells, leading to reduced transcriptional activity of YAP. While the functional significance of YAP cytoplasmic accumulation is yet to be investigated, our results reveal the common and distinct downstream pathways between PIK3CA amplification and mutation. These findings may be applicable to p110α-targeting therapies in serous ovarian cancer. Citation Format: Shibo Zhang, Hei Ip Hong, Victor CY Mak, Yuan Zhou, Panpan Wang, Lydia Wai Ting Cheung. Elucidation of the downstream signaling of PIK3CA genomic alterations in serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2553.

Extracellular matrix in high-grade serous ovarian cancer: Advances in understanding of carcinogenesis and cancer biology.

High-grade serous ovarian cancer (HGSOC) is notoriously known as the "silent killer" of post-menopausal women as it has an insidious progression and is the deadliest gynaecological cancer. Although a dual origin of HGSOC is now widely accepted, there is growing evidence that most cases of HGSOC originate from the fallopian tube epithelium. In this review, we will address the fallopian tube origin and involvement of the extracellular matrix (ECM) in HGSOC development. There is limited research on the role of ECM at the earliest stages of HGSOC carcinogenesis. Here we aim to synthesise current understanding of the contribution of ECM to each stage of HGSOC development and progression, beginning at serous tubal intraepithelial carcinoma (STIC) precursor lesions and proceeding across key events including dissemination of tumourigenic fallopian tube epithelial cells to the ovary, survival of these cells in peritoneal fluid as multicellular aggregates, and colonisation of the ovary. Likewise, as part of the metastatic series of events, serous ovarian cancer cells survive travel in peritoneal fluid, attach to, migrate across the mesothelium and invade into the sub-mesothelial matrix of secondary sites in the peritoneal cavity. Halting cancer at the pre-metastatic stage and finding ways to stop the dissemination of ovarian cancer cells from the primary site is critical for improving patient survival. The development of drug resistance also contributes to poor survival statistics in HGSOC. In this review, we provide an update on the involvement of the ECM in metastasis and drug resistance in HGSOC. Interplay between different cell-types, growth factor gradients as well as evolving ECM composition and organisation, creates microenvironment conditions that promote metastatic progression and drug resistance of ovarian cancer cells. By understanding ECM involvement in the carcinogenesis and chemoresistance of HGSOC, this may prompt ideas for further research for developing new early diagnostic tests and therapeutic strategies for HGSOC with the end goal of improving patient health outcomes.

Morpho-structural adaptations of the integument in different aquatic organisms

The integument acts as a barrier to protect the body from harmful pathogenic infectious agents, parasites, UV rays, trauma, and germs. The integument of invertebrates and vertebrates are structurally different: while invertebrates usually have a simple monolayer epidermis frequently covered by mucus, cuticles, or mineralized structures, vertebrates possess a multilayered epidermis with several specialized cells. This study aims to describe by morphological, histological, and immunohistochemical analyses, the morpho-structural adaptations throughout evolution of the integument of gastropod Aplysia depilans (Gmelin, 1791), ascidian Styela plicata (Lesuer, 1823), myxine hagfish Eptatretus cirrhatus (Forster, 1801) and teleost Heteropneustes fossilis (Bloch, 1794) for the first time, with special reference to sensory epidermal cells. Different types of cells could be identified that varied according to the species; including mucous cells, serous glandular cells, clavate cells, club cells, thread cells, and support cells. In all integuments of the specimens analyzed, sensory solitary cells were identified in the epidermis, immunoreactive to serotonin and calbindin. Our study provided an essential comparison of integuments, adding new information about sensory epidermal cells phylogenetic conservation and on the structural changes that invertebrates and vertebrates have undergone during evolution.

High ATP6V1B1 expression is associated with poor prognosis and platinum‑based chemotherapy resistance in epithelial ovarian cancer.

The vacuolar ATPase H+ transporting V1 subunit B1 (ATP6V1B1) belongs to the family of ATP6Vs, which functions to transport hydrogen ions. The expression of ATP6V1B1 and associated clinicopathological features have been linked to various cancers; however, its role in epithelial ovarian cancer (EOC) has remained to be explored. The present study aimed to unveil the function, molecular mechanisms and clinical significance of ATP6V1B1 in EOC. The mRNA levels of ATP6V1 subunits A, B1 and B2 in EOC tissues were determined using data from the Gene Expression Profiling Interactive Analysis database and RNA sequencing. Protein levels of ATP6V1B1 were evaluated through immunohistochemistry staining of EOC, borderline, benign and normal epithelial tissues. The association between ATP6V1B1 expression and clinicopathological features and prognosis of patients with EOC was analyzed. Furthermore, the biological role of ATP6V1B1 in ovarian cancer cell lines was also assessed. RNA sequencing and public dataset analyses revealed elevated ATP6V1B1 mRNA levels in EOCs. High ATP6V1B1 protein levels were also observed in EOC compared with those of borderline and benign tumors and nonadjacent normal epithelial tissues. High ATP6V1B1 expression was associated with the serous cell type, advanced International Federation of Gynecology and Obstetrics stage, high/advanced tumor grade, elevated serum cancer antigen 125 levels and platinum resistance (P<0.001, P<0.001, P=0.035, P=0.029 and P=0.011, respectively). High expression levels of ATP6V1B1 were also associated with poor overall and disease‑free survival (P<0.001). Knockdown of ATP6V1B1 decreased cancer cell proliferation and colony‑forming abilities (P<0.001) invitro by inducing cell cycle arrest in G0/G1 phase. Significant upregulation of ATP6V1B1 was observed in EOC and the prognostic significance and association with chemotherapy resistance of ATP6V1B1 in EOC was demonstrated, rendering it an EOC‑related biomarker for prognostic evaluation and chemotherapy resistance, as well as a potential therapeutic target for patients with EOC.

Morphology of the esophagus of ferrets and expression profile of molecular markers

To examine the morphological characteristics and the expression profile of molecular markers of ferret esophagus and assess the feasibility of using ferrets as animal models for studying human esophageal diseases. Frozen sections and paraffin- embedded specimens of the esophageal tissues were obtained from adult ferrets (aged 6 to 8 months) and ferrets aged 1 day, 3 days, 5 days, 1 week and 2 weeks. HE staining and periodic acid-Schiff (PAS) staining were used for morphological analysis of the esophageal submucosal glands (SMGs) of adult ferrets, and the expressions of MUC5B and MUC5AC were tested using Mucin staining; The expressions of cytokeratins (CK4, CK5, CK7, CK8, CK14, CK17, CK18, CK19, and CK20) in adult ferret esophagus were examined using HE staining and immunofluorescence assay. The expressions of LEF1 in the esophageal epithelium and SMGs were detected with immunofluorescence assay. In adult ferrets, the esophageal SMGs were connective tissues below the muscularis mucosa of the esophagus with secretory functions. Cytokeratins were expressed differentially in different esophageal cells: CK4, CK8 and CK20 were expressed mainly in the mucous cells, ductal cells and epithelial cells, respectively, while the mucous cells expressed the largest variety of cytokeratins. Mucin staining showed positive MUC5B and MUC5AC expression in the cytoplasm and lumen of adult ferret esophageal glands. Lectin from DBA, ECL, GSLI, GSL Ⅱ, SBA, Tacalin bioylated, ULEX, WGA, GSL Ⅰ and GSL Ⅱ were expressed on ductal cell membrane, and ECL, PNA and WGA were detected on epithelial cell membrane. Lectin with ConA, PHA-E and PHA-L were expressed on serous cell membrane. Immunofluorescence assay showed that LEF1 in the developing glands were visible from 3 days to 1 week of age and then disappeared as the glands matured. The intensity of LEF1 expression in the esophageal glands differed significantly between ferrets aged 1 to 7 days and those aged two weeks. Ferrets and human share similar esophageal tissue structures and some common molecular markers, suggesting the possibility of using ferrets as animal models of human esophageal diseases.