Milky spots: omental functional units and hotbeds for peritoneal cancer metastasis

Morphological differences between the lesser and the greater omenta in albino rats

BACKGROUND

Publications report that all mammals have two omenta, namely, lesser omentum and greater omentum. Basically, these organs, which share the same name except for the adjective "lesser" or "greater," should not differ from each other. However, no clear description of the structure of the lesser omentum, as well as comparative morphological analysis between the lesser and greater omenta have been found in the literature, which necessitates a thorough investigation. Therefore, the aim of our study was to analyze the morphofunctional differences between the greater and lesser omenta in albino rats.

METHOD

The experiment involved 20 mature male albino rats, weighing 298,28±7,36 grams. The material for our study were preparations of lesser and greater omenta, fixed in 10 % of neutral buffered formalin. Paraffin sections were stained with hematoxylin-eosin and Van Gieson stain.

RESULTS

The findings of the study showed that the greater omentum in albino rats, unlike other derivatives of the omentum (ligaments and mesenteries), represents a free extension (mostly from the greater curvature of the stomach), in the form of an "apron," into a specific depth of the peritoneal cavity, duplicating the serous membrane. This duplication is characterized by the composition of two structurally interdependent formations. These include vascular-fatty arcades, associated with lymphoid nodules known as milky spots, and binding serous-reticular membranes. The findings of the study of the lesser omentum have established that in all cases it is located beneath the liver and becomes visualized only after hepatolifting. It is presented in the form of two ligaments: hepatoduodenal and hepatogastric, which contain two main structured formations, which we called vascular-fatty spurs, between these spurs, serous-reticular membranes are located.

CONCLUSION

despite having similar names, the lesser omentum, a derivative of the peritoneum, is fundamentally different. As it is well known, the lesser omentum is represented by ligaments that extend from the liver hilus to the lesser curvature of the stomach and the duodenum. Due to this arrangement, the lesser omentum lacks the mobile activity characteristic of the greater omentum, which plays a crucial role in rapid response to damage in the gastrointestinal tract. Despite sharing the same names, both formations differ in shape, morphological structure, development and function.

Effect of omentum preservation on long-term prognosis of locally advanced gastric cancer: a systematic review and meta-analysis

BACKGROUND

The effect of omentum preservation (OP) on locally advanced gastric cancer (LAGC) remains controversial. This study aimed to investigate the long-term prognosis of LAGC patients with OP versus omentum resection (OR).

METHODS

A comprehensive search of databases including PubMed, Web of Science, Embase, and Cochrane Library was conducted up until February 2024. Statistical analysis was performed using Stata 12.0 software. The primary outcome was to assess the impact of OP on the long-term prognosis of patients with LAGC, including overall survival (OS) and recurrence-free survival (RFS).

RESULTS

A total of six case-control studies were included, encompassing a cohort of 1897 patients. The OP group consisted of 844 patients, while the OR group comprised 1053 patients. The study results showed that the OS (HR = 0.72, 95% CI: 0.58-0.90, P = 0.003) and 5-year RFS (HR = 0.79, 95% CI: 0.63-0.99, P = 0.038) in the OP group were superior to those observed in the OR group. Subgroup analysis indicated that 5-year OS (HR = 0.64, P = 0.003) and 5-year RFS (HR = 0.69, P = 0.005) in the OP group were also better than those in the OR group in Korea. However, the subgroup analysis conducted on stage T3-T4 tumors revealed no statistically significant differences in OS (P = 0.083) and 5-year RFS (P = 0.173) between the two groups.

CONCLUSION

Compared with OR, OP shows non-inferiority in patients with LAGC and can be considered a potential treatment option for radical gastrectomy.

The Peritoneum: Anatomy, Pathologic Findings, and Patterns of Disease Spread

Disease spread in the abdomen and pelvis generally occurs in a predictable pattern in relation to anatomic landmarks and fascial planes. Anatomically, the abdominopelvic cavity is subdivided into several smaller spaces or compartments by key ligaments and fascial planes. The abdominal cavity has been traditionally divided into peritoneal, retroperitoneal, and pelvic extraperitoneal spaces. Recently, more clinically relevant classifications have evolved. Many pathologic conditions affect the abdominal cavity, including traumatic, inflammatory, infectious, and neoplastic processes. These abnormalities can extend beyond their sites of origin through various pathways. Identifying the origin of a disease process is the first step in formulating a differential diagnosis and ultimately reaching a final diagnosis. Pathologic conditions differ in terms of pathways of disease spread. For example, simple fluid tracks along fascial planes, respecting anatomic boundaries, while fluid from acute necrotizing pancreatitis can destroy fascial planes, resulting in transfascial spread without regard for anatomic landmarks. Furthermore, neoplastic processes can spread through multiple pathways, with a propensity for spread to noncontiguous sites. When the origin of a disease process is not readily apparent, recognizing the spread pattern can allow the radiologist to work backward and ultimately arrive at the site or source of pathogenesis. As such, a cohesive understanding of the peritoneal anatomy, the typical organ or site of origin for a disease process, and the corresponding pattern of disease spread is critical not only for initial diagnosis but also for establishing a road map for staging, anticipating further disease spread, guiding search patterns and report checklists, determining prognosis, and tailoring appropriate follow-up imaging studies. ©RSNA, 2024 Supplemental material is available for this article.

Vagus nerve signal has an inhibitory influence on the development of peritoneal metastasis in murine gastric cancer

The vagus nerve is the only pathway for transmitting parasympathetic signals between the brain and thoracoabdominal organs, thereby exhibiting anti-inflammatory functions through the cholinergic anti-inflammatory pathway. Despite often being resected during lymph node dissection in upper gastrointestinal cancer surgery, the impact of vagotomy on postoperative outcomes in gastric cancer patients remains unclear. Sub-diaphragmatic vagotomy was performed on C57BL/6 mice. Three weeks later, syngeneic murine gastric cancer cell line YTN16P was injected into the peritoneal cavity, and the number of peritoneal metastases (PM) on the mesentery and omentum compared with control mice. The phenotypes of immune cells in peritoneal lavage and omental milky spots one day after tumor inoculation were analyzed using flow cytometry and immunohistochemistry. Intraperitoneal transfer of 3 × 105 YTN16P significantly increased the number of metastatic nodules on the mesentery in the vagotomy group compared to the control group. The omental metastasis grade was also significantly higher in the vagotomy group. Phenotypic analysis of immune cells in peritoneal lavage did not reveal significant differences after vagotomy. However, vagotomized mice exhibited a notable increase in milky spot area, with a higher presence of cytokeratin(+) tumor cells, F4/80(+) macrophages, and CD3(+) T cells. Vagus nerve signaling appears to regulate the immune response dynamics within milky spots against disseminated tumor cells and inhibits the development of PM. Preserving the vagus nerve may offer advantages in advanced gastric cancer surgery to reduce peritoneal recurrence.

Reciprocal crosstalk between Th17 and mesothelial cells promotes metastasis-associated adhesion of ovarian cancer cells

BACKGROUND

IL-17A and TNF synergistically promote inflammation and tumorigenesis. Their interplay and impact on ovarian carcinoma (OC) progression are, however, poorly understood. We addressed this question focusing on mesothelial cells, whose interaction with tumor cells is known to play a pivotal role in transcoelomic metastasis formation.

METHODS

Flow-cytometry and immunohistochemistry experiments were employed to identify cellular sources of IL-17A and TNF. Changes in transcriptomes and secretomes were determined by bulk and single cell RNA sequencing as well as affinity proteomics. Functional consequences were investigated by microscopic analyses and tumor cell adhesion assays. Potential clinical implications were assessed by immunohistochemistry and survival analyses.

RESULTS

We identified Th17 cells as the main population of IL-17A- and TNF producers in ascites and detected their accumulation in early omental metastases. Both IL-17A and its receptor subunit IL-17RC were associated with short survival of OC patients, pointing to a role in clinical progression. IL-17A and TNF synergistically induced the reprogramming of mesothelial cells towards a pro-inflammatory mesenchymal phenotype, concomitantly with a loss of tight junctions and an impairment of mesothelial monolayer integrity, thereby promoting cancer cell adhesion. IL-17A and TNF synergistically induced the Th17-promoting cytokines IL-6 and IL-1β as well as the Th17-attracting chemokine CCL20 in mesothelial cells, indicating a reciprocal crosstalk that potentiates the tumor-promoting role of Th17 cells in OC.

CONCLUSIONS

Our findings reveal a novel function for Th17 cells in the OC microenvironment, which entails the IL-17A/TNF-mediated induction of mesothelial-mesenchymal transition, disruption of mesothelial layer integrity and consequently promotion of OC cell adhesion. These effects are potentiated by a positive feedback loop between mesothelial and Th17 cells. Together with the observed clinical associations and accumulation of Th17 cells in omental micrometastases, our observations point to a potential role in early metastases formation and thus to new therapeutic options.

Laparoscopic harvest and free transplantation of great omentum flap for extensive tissue defects in complex wounds

INTRODUCTION

The repair of extensive tissue defects remains a challenge, although great progress has been made in reconstructive surgery. The transplantation of a single huge flap or several flaps in combination will inevitably result in donor-site morbidity. Here we report our experience in the repair of these wounds with laparoscopically harvested great omentum flaps.

METHODS

Twelve patients with extensive tissue defects caused by deep burn injury, avulsion injury, and open fracture underwent free omental flap transplantation and split-thickness skin grafting. The patient demographics, wound characteristics, and complications postsurgical operation were recorded. Prior to omentum flap transplantation, these patients underwent debridement, vacuum sealing drainage treatment, and/or fixation of fractures. All omentum flaps harvested using laparoscopic technique were anastomosed to recipient vessels, and split-thickness skin grafting was performed 14 days after omental flap transplantation.

RESULTS

The mean defect size was 471 cm2 and the mean omental flap size was 751.1 cm2. Among all 12 cases, the omental flaps survived well except for distal partial necrosis in one case. Skin grafting was also achieved in all cases, and all patients achieved complete wound coverage. All donor sites achieved primary healing without major complications. The mean follow-up time was 30 months with satisfactory appearance and functional outcome.

CONCLUSION

For the reconstruction of extensive tissue defects in complex wounds, the free transfer of an omental flap may be an ideal option because of its well-vascularized and pliable tissue with reliable vascular anatomy, as well as minimized donor-site morbidity.

A Recipe for Successful Metastasis: Transition and Migratory Modes of Ovarian Cancer Cells

One of the characteristic features of ovarian cancer is its early dissemination. Metastasis and the invasiveness of ovarian cancer are strongly dependent on the phenotypical and molecular determinants of cancer cells. Invasive cancer cells, circulating tumor cells, and cancer stem cells, which are responsible for the metastatic process, may all undergo different modes of transition, giving rise to mesenchymal, amoeboid, and redifferentiated epithelial cells. Such variability is the result of the changing needs of cancer cells, which strive to survive and colonize new organs. This would not be possible if not for the variety of migration modes adopted by the transformed cells. The most common type of metastasis in ovarian cancer is dissemination through the transcoelomic route, but transitions in ovarian cancer cells contribute greatly to hematogenous and lymphatic dissemination. This review aims to outline the transition modes of ovarian cancer cells and discuss the migratory capabilities of those cells in light of the known ovarian cancer metastasis routes.

Defining the Role of Metastasis-Initiating Cells in Promoting Carcinogenesis in Ovarian Cancer

Ovarian cancer is the deadliest gynecological malignancy with a high prevalence of transcoelomic metastasis. Metastasis is a multi-step process and only a small percentage of cancer cells, metastasis-initiating cells (MICs), have the capacity to finally establish metastatic lesions. These MICs maintain a certain level of stemness that allows them to differentiate into other cell types with distinct transcriptomic profiles and swiftly adapt to external stresses. Furthermore, they can coordinate with the microenvironment, through reciprocal interactions, to invade and establish metastases. Therefore, identifying, characterizing, and targeting MICs is a promising strategy to counter the spread of ovarian cancer. In this review, we provided an overview of OC MICs in the context of characterization, identification through cell surface markers, and their interactions with the metastatic niche to promote metastatic colonization.

Advanced Glycation End Products as a Potential Target for Restructuring the Ovarian Cancer Microenvironment: A Pilot Study

Ovarian cancer is the sixth leading cause of cancer-related death in women, and both occurrence and mortality are increased in women over the age of 60. There are documented age-related changes in the ovarian cancer microenvironment that have been shown to create a permissive metastatic niche, including the formation of advanced glycation end products, or AGEs, that form crosslinks between collagen molecules. Small molecules that disrupt AGEs, known as AGE breakers, have been examined in other diseases, but their efficacy in ovarian cancer has not been evaluated. The goal of this pilot study is to target age-related changes in the tumor microenvironment with the long-term aim of improving response to therapy in older patients. Here, we show that AGE breakers have the potential to change the omental collagen structure and modulate the peritoneal immune landscape, suggesting a potential use for AGE breakers in the treatment of ovarian cancer.

Intraperitoneal metastasis of ovarian cancer: new insights on resident macrophages in the peritoneal cavity

Ovarian cancer metastasis occurs primarily in the peritoneal cavity. Orchestration of cancer cells with various cell types, particularly macrophages, in the peritoneal cavity creates a metastasis-favorable environment. In the past decade, macrophage heterogeneities in different organs as well as their diverse roles in tumor settings have been an emerging field. This review highlights the unique microenvironment of the peritoneal cavity, consisting of the peritoneal fluid, peritoneum, and omentum, as well as their own resident macrophage populations. Contributions of resident macrophages in ovarian cancer metastasis are summarized; potential therapeutic strategies by targeting such cells are discussed. A better understanding of the immunological microenvironment in the peritoneal cavity will provide a stepping-stone to new strategies for developing macrophage-based therapies and is a key step toward the unattainable eradication of intraperitoneal metastasis of ovarian cancer.

A Randomized Double-Blind Controlled Proof-of-Concept Study of Alanyl-Glutamine for Reduction of Post-Myomectomy Adhesions

STUDY OBJECTIVE

To test the hypothesis that intraperitoneal instillation of a single bolus dose of l-alanyl-l-glutamine (AG) will reduce the incidence, extent and/or severity of adhesions following myomectomy and establish preliminary safety and tolerability of AG in humans.

DESIGN

Phase 1,2 Randomized, double-blind, placebo-controlled study (DBRCT).

SETTING

Tertiary care gynecology surgical centre.

PATIENTS

Thirty-eight women who underwent myomectomies by laparoscopy (N = 38; AG-19 vs Placebo-19) or laparotomy (N = 10; AG-5 vs Placebo-5) with a scheduled second-look laparoscopy (SLL) 6-8 weeks later. Thirty-two patients in the laparoscopy arm completed SLL.

INTERVENTIONS

Bolus dose of AG or normal saline solution control (0.9% NaCl) administered intraperitoneally immediately prior to suture closure of the laparoscopic ports. The average dose was 170 mL of AG or control based on a dosing scheme of 1 g/kg bodyweight.

MEASUREMENTS

Digital recordings obtained for all procedures. The primary endpoint was reduction in the incidence, severity and extent of post-operative adhesions analyzed by intention-to-treat (ITT) approach. Three independent, blinded reviewers evaluated all operative video recordings to assess presence of adhesions. Post-hoc analysis assessed presence or absence of adhesions in the peritoneal cavity. Secondary endpoints assessed safety and tolerability of AG.

MAIN RESULTS

Administration of AG reduced the incidence, severity and/or extent of post-operative adhesions (p = 0.046). The presence of adhesions in the AG group was lower than in the Control group (p = 0.041). Adhesion improvement was achieved in 15 of 15 (100%) in the AG group versus 5 of 17 (29.6%) in the placebo group. No serious adverse events were reported. No differences in safety parameters were observed.

CONCLUSIONS

Intraperitoneal l-alanyl-l-glutamine reduced adhesion formation in all patients following laparoscopic myomectomy. Complete absence of adhesions was achieved at all abdominal sites in 93% of patients. Results confirm AG's known effects on cellular mechanisms of adhesiogenesis and lay the foundation for new adhesion prophylaxis research and treatment.

A 3D multi-cellular tissue model of the human omentum to study the formation of ovarian cancer metastasis

Reliable and predictive experimental models are urgently needed to study metastatic mechanisms of ovarian cancer cells in the omentum. Although models for ovarian cancer cell adhesion and invasion were previously investigated, the lack of certain omental cell types, which influence the metastatic behavior of cancer cells, limits the application of these tissue models. Here, we describe a 3D multi-cellular human omentum tissue model, which considers the spatial arrangement of five omental cell types. Reproducible tissue models were fabricated combining permeable cell culture inserts and bioprinting technology to mimic metastatic processes of immortalized and patient-derived ovarian cancer cells. The implementation of an endothelial barrier further allowed studying the interaction between cancer and endothelial cells during hematogenous dissemination and the impact of chemotherapeutic drugs. This proof-of-concept study may serve as a platform for patient-specific investigations in personalized oncology in the future.

Occult Omental Metastasis in Gastric Adenocarcinoma: An Analysis of Incidence, Predictors, and Outcomes

Negine PaulIntroduction  Traditionally, the concept of complete omentectomy during gastric resection for cancer was based on lymphatic drainage and the occurrence of occult omental metastasis (OM). However, recent emerging evidence has challenged this concept of complete omentectomy. We, therefore, aim to find the incidence and risk factors of occult OM and also evaluate the outcome of patients with and without such metastasis. Methods  This is a single institutional, retrospective study of patients with gastric cancer who underwent curative radical gastrectomy for a period of 3 years (April 1, 2016, to March 31, 2019). A complete omentectomy was performed in all patients and the omentum and nodal stations were dissected in the resected specimen and sent for pathological analysis. Clinical and epidemiological data were collected from the hospital patient database and analysis was done. Results  A total of 185 patients have been included in the study, with a mean age of 53.84 years. Twenty of the 185 patients had OM (10.8%). Age, sex, location of the tumor, and neoadjuvant chemotherapy were not statistically significant in predicting OM. However, tumor size and tumor depth were found to have a significant association with OM. The occurrence of OM was more likely to be associated with disease recurrence, especially in the peritoneum. The mean overall survival was 38.15 months (±3.33 SD), whereas patients with OM had lower survival, 23.31 months (±7.79 SD), with a p -value of 0.012. Conclusion  OM was not encountered in T1 and T2 gastric cancers and the incidence of OM in T3 and T4 tumors was approximately 12.7%. Therefore, complete omentectomy may be omitted in early T1/T2 tumors. OM was associated with poor prognosis, increased peritoneal recurrence, and decreased overall survival, in spite of a complete omentectomy, and may serve as a prognostic indicator for disease recurrence and overall survival.

Microrobotic swarms for selective embolization

Inspired by the collective intelligence in natural swarms, microrobotic agents have been controlled to form artificial swarms for targeted drug delivery, enhanced imaging, and hyperthermia. Different from these well-investigated tasks, this work aims to develop microrobotic swarms for embolization, which is a clinical technique used to block blood vessels for treating tumors, fistulas, and arteriovenous malformations. Magnetic particle swarms were formed for selective embolization to address the low selectivity of the present embolization technique that is prone to cause complications such as stroke and blindness. We established an analytical model that describes the relationships between fluid viscosity, flow rate, branching angle, magnetic field strength, and swarm integrity, based on which an actuation strategy was developed to maintain the swarm integrity inside a targeted region under fluidic flow conditions. Experiments in microfluidic channels, ex vivo tissues, and in vivo porcine kidneys validated the efficacy of the proposed strategy for selective embolization.

Immune response and locoregional treatments for peritoneal carcinomatosis

Peritoneal Carcinomatosis (PC) is considered as a terminal disease with short survival. It is treated with palliative therapies, consisting of repeated drainages and sometimes instillation of chemotherapy. Since the nineties, surgery has been combined with more effective systemic chemotherapy, intraperitoneal chemotherapy and hyperthermic intraperitoneal chemotherapy (HIPEC) for the treatment of PC. This combination therapy significantly increases the overall survival of selected PC patients. The understanding of how intraperitoneal chemotherapy and HIPEC can cure patients is still unclear. Experts hypothesized that the efficacy is obtained by the ability of high peritoneal drug exposure and hyperthermia to directly kill cancer cells. Several studies indicate that cancer cells death directly influences the response of the immune system. For this reason, the protective effect of intraperitoneal chemotherapy and HIPEC could be mediated by its ability to kill cancer cells in an immuno-genic way, causing an efficient anticancer immune response. In this review, we investigate the role of the innate peritoneal or locoregional therapy-induced immune response in PC therapy.

The tumor immune microenvironment in peritoneal carcinomatosis

One in four patients with colorectal cancer, 40% of gastric cancer patients, and 60% of ovarian cancer patients will develop peritoneal metastases (PM) in the course of their disease. The outcome of patients with widespread PM remains poor with currently available treatments. Despite the relatively common occurrence of PM, little is known on the pathophysiology that drives the peritoneal metastatic cascade. It is increasingly recognized that the stromal components of the peritoneal microenvironment play an essential role in tumor progression. However, little is known about the specific interactions and components of the peritoneal tumor microenvironment, particularly with respect the immune cell population. We summarize the current knowledge of the tumor immune microenvironment (TIME) in peritoneal metastases originating from the three most common origins: ovarian, gastric, and colorectal cancer. Clearly, the TIME is highly heterogeneous and its composition and functional activity differ according to tumor type and, within the same patient, according to anatomical location. The TIME in PM remains to be explored in detail, and further elucidation of their immune contexture may allow biology driven design of novel immune modulating or immune targeting therapies.

Spheroid Formation and Peritoneal Metastasis in Ovarian Cancer: The Role of Stromal and Immune Components

Ovarian cancer (OC) is one of the most common gynecological cancers, with the worst prognosis and the highest mortality rate. Peritoneal dissemination (or carcinomatosis) accompanied by ascites formation is the most unfavorable factor in the progression and recurrence of OC. Tumor cells in ascites are present as either separate cells or, more often, as cell aggregates, i.e., spheroids which promote implantation on the surface of nearby organs and, at later stages, metastases to distant organs. Malignant ascites comprises a unique tumor microenvironment; this fact may be of relevance in the search for new prognostic and predictive factors that would make it possible to personalize the treatment of patients with OC. However, the precise mechanisms of spheroid formation and carcinomatosis are still under investigation. Here, we summarize data on ascites composition as well as the activity of fibroblasts and macrophages, the key stromal and immune components, in OC ascites. We describe current knowledge about the role of fibroblasts and macrophages in tumor spheroid formation, and discuss the specific functions of fibroblasts, macrophages and T cells in tumor peritoneal dissemination and implantation.

Immune Niche Within the Peritoneal Cavity

There are numbers of leukocytes present in peritoneal cavity, not only protecting body cavity from infection but also contributing to peripheral immunity including natural antibody production in circulation. The peritoneal leukocytes compose unique immune compartment, the functions of which cannot be replaced by other lymphoid organs. Atypical lymphoid clusters, called "milky spots", that are located in visceral adipose tissue omentum have the privilege of immune niche in terms of differentiation, recruitment, and activation of peritoneal immunity, yet mechanisms underlying the regulation are underexplored. In this review, I discuss the emerging views of peritoneal immune system in the contexts of its development, organization, and functions.

Integrating Cancer Vaccines in the Standard-of-Care of Ovarian Cancer: Translating Preclinical Models to Human

Simple Summary

The overall survival of ovarian cancer (OC) remains poor for most patients. Despite incorporation of novel therapeutic agents such as bevacizumab and PARP inhibitors to OC standard-of-care, efficacy is only observed in a subset of patients. Cancer vaccination has demonstrated effectiveness in OC patients and could be considered for potential incorporation into OC standard-of-care. This review provides an overview of the different types of cancer vaccination strategies and discusses the use of murine OC tumor models to evaluate combinatorial regimens comprising cancer vaccines and OC standard-of-care.

Abstract

As the majority of ovarian cancer (OC) patients are diagnosed with metastatic disease, less than 40% will survive past 5 years after diagnosis. OC is characterized by a succession of remissions and recurrences. The most promising time point for immunotherapeutic interventions in OC is following debulking surgery. Accumulating evidence shows that T cells are important in OC; thus, cancer vaccines capable of eliciting antitumor T cells will be effective in OC treatment. In this review, we discuss different cancer vaccines and propose strategies for their incorporation into the OC standard-of-care regimens. Using the murine ID8 ovarian tumor model, we provide evidence that a cancer vaccine can be effectively combined with OC standard-of-care to achieve greater overall efficacy. We demonstrate several important similarities between the ID8 model and OC patients, in terms of response to immunotherapies, and the ID8 model can be an important tool for evaluating combinatorial regimens and clinical trial designs in OC. Other emerging models, including patient-derived xenograft and genetically engineered mouse models, are continuing to improve and can be useful for evaluating cancer vaccination therapies in the near future. Here, we provide a comprehensive review of the completed and current clinical trials evaluating cancer vaccines in OC.

Potential Role of Diabetes Mellitus-Associated T Cell Senescence in Epithelial Ovarian Cancer Omental Metastasis

Epithelial ovarian cancer (EOC) is one of the most common causes of cancer-related deaths among women and is associated with age and age-related diseases. With increasing evidence of risks associated with metabolic inflammatory conditions, such as obesity and type 2 diabetes mellitus (T2DM), it is important to understand the complex pathophysiological mechanisms underlying cancer progression and metastasis. Age-related conditions can lead to both genotypic and phenotypic immune function alterations, such as induction of senescence, which can contribute to disease progression. Immune senescence is a common phenomenon in the ageing population, which is now known to play a role in multiple diseases, often detrimentally. EOC progression and metastasis, with the highest rates in the 75-79 age group in women, have been shown to be influenced by immune cells within the "milky spots" or immune clusters of the omentum. As T2DM has been reported to cause T cell senescence in both prediabetic and diabetic patients, there is a possibility that poor prognosis in EOC patients with T2DM is partly due to the accumulation of senescent T cells in the omentum. In this review, we explore this hypothesis with recent findings, potential therapeutic approaches, and future directions.

Evaluating Targeted Therapies in Ovarian Cancer Metabolism: Novel Role for PCSK9 and Second Generation mTOR Inhibitors

BACKGROUND

Dysregulated lipid metabolism is emerging as a hallmark in several malignancies, including ovarian cancer (OC). Specifically, metastatic OC is highly dependent on lipid-rich omentum. We aimed to investigate the therapeutic value of targeting lipid metabolism in OC. For this purpose, we studied the role of PCSK9, a cholesterol-regulating enzyme, in OC cell survival and its downstream signaling. We also investigated the cytotoxic efficacy of a small library of metabolic (n = 11) and mTOR (n = 10) inhibitors using OC cell lines (n = 8) and ex vivo patient-derived cell cultures (PDCs, n = 5) to identify clinically suitable drug vulnerabilities. Targeting PCSK9 expression with siRNA or PCSK9 specific inhibitor (PF-06446846) impaired OC cell survival. In addition, overexpression of PCSK9 induced robust AKT phosphorylation along with increased expression of ERK1/2 and MEK1/2, suggesting a pro-survival role of PCSK9 in OC cells. Moreover, our drug testing revealed marked differences in cytotoxic responses to drugs targeting metabolic pathways of high-grade serous ovarian cancer (HGSOC) and low-grade serous ovarian cancer (LGSOC) PDCs. Our results show that targeting PCSK9 expression could impair OC cell survival, which warrants further investigation to address the dependency of this cancer on lipogenesis and omental metastasis. Moreover, the differences in metabolic gene expression and drug responses of OC PDCs indicate the existence of a metabolic heterogeneity within OC subtypes, which should be further explored for therapeutic improvements.

New insights into M1/M2 macrophages: key modulators in cancer progression

Infiltration of macrophages in and around tumor nest represents one of the most crucial hallmarks during tumor progression. The mutual interactions with tumor cells and stromal microenvironment contribute to phenotypically polarization of tumor associated macrophages. Macrophages consist of at least two subgroups, M1 and M2. M1 phenotype macrophages are tumor-resistant due to intrinsic phagocytosis and enhanced antitumor inflammatory reactions. Contrastingly, M2 are endowed with a repertoire of tumor-promoting capabilities involving immuno-suppression, angiogenesis and neovascularization, as well as stromal activation and remodeling. The functional signature of M2 incorporates location-related, mutually connected, and cascade-like reactions, thereby accelerating paces of tumor aggressiveness and metastasis. In this review, mechanisms underlying the distinct functional characterization of M1 and M2 macrophages are demonstrated to make sense of M1 and M2 as key regulators during cancer progression.

Pentraxin-3 inhibits milky spots metastasis of gastric cancer by inhibiting M2 macrophage polarization

Purpose: Recent studies have indicated that Pentraxin-3 (PTX3) is related to invasion, migration and metastasis of gastric cancer cells (GCCs). However, the function of PTX3 in stemness and tumor-associated macrophages (TAMs) polarization in GC has not yet been revealed. Here, we investigated the role of PTX3 in TAMs polarization and stemness in gastric cancer (GC), and further explored the effect of PTX3 on milky spot metastasis of gastric cancer.

Methods: PTX3 expression in human gastric cancer tissues was examined with immunohistochemistry (IHC). The influence on stemness of gastric cancer cells was examined by sphere formation assay and western blot. qRT-PCR, IHC and flow cytometry were used to evaluate M1/M2 macrophage signatures. The effects of PTX3 on TAM polarization and milky spots were investigated in vitro and in vivo. The possible mechanism of PTX3 on targeted cytokines and pathway were analyzed by qRT-PCR and western blot.

Results: We found that PTX3 was low expressed in gastric carcinoma tissues and associated with stemness and polarization of macrophages. The upregulation of PTX3 inhibited the stemness of GCCs. Furthermore, PTX3 suppressed the polarization of M2 macrophages in the milky spots in vivo and in vitro and inhibited the metastasis of GC into milky spots. PTX3 restrained the expression of interleukin-4 (IL-4) and IL-10 via the inhibition of phosphorylation of the c-Jun N-terminal protein kinase 1/2 (JNK1/2) in GCCs.

Conclusion: These results revealed a novel mechanism of PTX3 in GC, which may participate in the development and metastasis of GC by affecting stemness and macrophage polarization. PTX3 should be considered as a crucial biomarker and may be potentially used in targeted therapy in GC progression.

Hyperthermia generated by magnetic nanoparticles for effective treatment of disseminated peritoneal cancer in an orthotopic nude-mouse model

Magnetic hyperthermia (MHT), which combines magnetic nanoparticles (MNPs) with an alternating magnetic field (AMF), holds promise as a cancer therapy. There have been many studies about hyperthermia, most of which have been performed by direct injection of MNPs into tumor tissues. However, there have been no reports of treating peritoneal disseminated disease with MHT to date. In the present study, we treated peritoneal metastasis of gastric cancer with MHT using superparamagnetic iron oxide (Fe3O4) nanoparticle (SPION) coated with carboxydextran as an MNP, in an orthotopic mouse model mimicking early peritoneal disseminated disease of gastric cancer. SPIONs of an optimal size were intraperitoneally administered, and an AMF (390 kHz, 28 kAm-1) was applied for 10 minutes, four times every three days. Three weeks after the first MHT treatment, the peritoneal metastases were significantly inhibited compared with the AMF-alone group or the untreated-control group. The results of the present study show that MHT can be applied as a new treatment option for disseminated peritoneal gastric cancer.Abbreviations: AMF: alternating magnetic field; Cy1: cytology-positive; DMEM: Dulbecco's Modified Eagle's Medium; FBS: fetal bovine serum; H&E: hematoxylin and eosin; HIPEC: hyperthermic intraperitoneal chemotherapy; MEM: Minimum Essential Medium; MHT: magnetic hyperthermia; MNPs: magnetic nanoparticles; P0: macroscopic peritoneal dissemination; RFP: red fluorescent protein; SPION: superparamagnetic iron oxide (Fe3O4) nanoparticle.

Humanized anti-DEspR IgG4S228P antibody increases overall survival in a pancreatic cancer stem cell-xenograft peritoneal carcinomatosis ratnu/nu model

BACKGROUND

Pancreatic peritoneal carcinomatosis (PPC), with the worst median overall-survival (mOS), epitomizes the incurability of metastatic cancer. Cancer stem cells (CSCs) underpin this incurability. However, inhibitors of CSC-stemness fail to increase mOS in cancer patients despite preclinical tumor-reduction. This shortfall reinforces that preclinical efficacy should be defined by increased mOS in the presence of cancer comorbidities, CSC-heterogeneity and plasticity. The primary objectives of this study are: to test the dual endothelin-1/signal peptide receptor, DEspR, as a nodal therapeutic target in PPC, given DEspR induction in anoikis-resistant pancreatic CSCs, and to validate humanized anti-DEspR antibody, hu-6g8, as a potential therapeutic for PPC.

METHODS

We used heterogeneous pools of CSCs selected for anoikis resistance from reprogrammed Panc1 and MiaPaCa2 tumor cells (TCs), and adherent TCs reprogrammed from CSCs (cscTCs). We used multiple anti-DEspR blocking antibodies (mAbs) with different epitopes, and a humanized anti-DEspR recombinant mAb cross-reactive in rodents and humans, to test DEspR inhibition effects. We measured DEspR-inhibition efficacy on multiple prometastatic CSC-functions in vitro, and on tumorigenesis and overall survival in a CSC-derived xenograft (CDX) nude rat model of PPC with comorbidities.

RESULTS

Here we show that DEspR, a stress-survival receptor, is present on subsets of PDAC Panc1-TCs, TC-derived CSCs, and CSC-differentiated TCs (cscTCs), and that DESpR-inhibition decreases apoptosis-resistance and pro-metastatic mesenchymal functions of CSCs and cscTCs in vitro. We resolve the DNA-sequence/protein-function discordance by confirming ADAR1-RNA editing-dependent DEspR-protein expression in Panc1 and MiaPaCa2 TCs. To advance DEspR-inhibition as a nodal therapeutic approach for PPC, we developed and show improved functionality of a recombinant, humanized anti-DEspR IgG4S228P antibody, hu-6g8, over murine precursor anti-DEspR mabs. Hu-6g8 internalizes and translocates to the nucleus colocalized with cyto-nuclear shuttling galectins-1/3, and induces apoptotic cell changes. DEspR-inhibition blocks transperitoneal dissemination and progression to peritoneal carcinomatosis of heterogeneous DEspR±/CD133 ± Panc1-derived CSCs in xenografted nude rats, improving mOS without chemotherapy-like adverse effects. Lastly, we show DEspR expression in Stage II-IV primary and invasive TCs in the stroma in PDAC-patient tumor arrays.

CONCLUSION

Collectively, the data support humanized anti-DEspR hu-6g8 as a potential targeted antibody-therapeutic with promising efficacy, safety and prevalence profiles for PPC patients.

Targeting the tumour microenvironment in platinum-resistant ovarian cancer

Ovarian cancer typically presents at an advanced stage, and although the majority of cases initially respond well to platinum-based therapies, chemoresistance almost always occurs leading to a poor long-term prognosis. While various cellular autonomous mechanisms contribute to intrinsic or acquired platinum resistance, the tumour microenvironment (TME) plays a central role in resistance to therapy and disease progression by providing cancer stem cell niches, promoting tumour cell metabolic reprogramming, reducing chemotherapy drug perfusion and promoting an immunosuppressive environment. As such, the TME is an attractive therapeutic target which has been the focus of intense research in recent years. This review provides an overview of the unique ovarian cancer TME and its role in disease progression and therapy resistance, highlighting some of the latest preclinical and clinical data on TME-targeted therapies. In particular, it focuses on strategies targeting cancer-associated fibroblasts, tumour-associated macrophages, cancer stem cells and cancer cell metabolic vulnerabilities.

Possible Role of Metformin as an Immune Modulator in the Tumor Microenvironment of Ovarian Cancer

Growing evidence suggests that the immune component of the tumor microenvironment (TME) may be highly involved in the progression of high-grade serous ovarian cancer (HGSOC), as an immunosuppressive TME is associated with worse patient outcomes. Due to the poor prognosis of HGSOC, new therapeutic strategies targeting the TME may provide a potential path forward for preventing disease progression to improve patient survival. One such postulated approach is the repurposing of the type 2 diabetes medication, metformin, which has shown promise in reducing HGSOC tumor progression in retrospective epidemiological analyses and through numerous preclinical studies. Despite its potential utility in treating HGSOC, and that the immune TME is considered as a key factor in the disease’s progression, little data has definitively shown the ability of metformin to target this component of the TME. In this brief review, we provide a summary of the current understanding of the effects of metformin on leukocyte function in ovarian cancer and, coupled with data from other related disease states, posit the potential mechanisms by which the drug may enhance the anti-tumorigenic effects of immune cells to improve HGSOC patient survival.

Modeling the Early Steps of Ovarian Cancer Dissemination in an Organotypic Culture of the Human Peritoneal Cavity

The majority of ovarian cancer patients present clinically with wide-spread metastases throughout the peritoneal cavity, metastasizing to the mesothelium-lined peritoneum and visceral adipose depots within the abdomen. This unique metastatic tumor microenvironment is comprised of multiple cell types, including mesothelial cells, fibroblasts, adipocytes, macrophages, neutrophils, and T lymphocytes. Modeling advancements, including complex 3D systems and organoids, coupled with 2D cocultures, in vivo mouse models, and ex vivo human tissue cultures have greatly enhanced our understanding of the tumor-stroma interactions that are required for successful metastasis of ovarian cancer cells. However, advanced multifaceted model systems that incorporate frequency and spatial distribution of all cell types present in the tumor microenvironment of ovarian cancer are needed to enhance our knowledge of ovarian cancer biology in order to identify methods for preventing and treating metastatic disease. This review highlights the utility of recently developed modeling approaches, summarizes some of the resulting progress using these techniques, and suggests how these strategies may be implemented to elucidate signaling processes among cell types of the tumor microenvironment that promote ovarian cancer metastasis.

Toward a Consensus View of Mammalian Adipocyte Stem and Progenitor Cell Heterogeneity

White adipose tissue (WAT) is a cellularly heterogeneous endocrine organ that not only serves as an energy reservoir, but also actively participates in metabolic homeostasis. Among the main constituents of adipose tissue are adipocytes, which arise from adipose stem and progenitor cells (ASPCs). While it is well known that these ASPCs reside in the stromal vascular fraction (SVF) of adipose tissue, their molecular heterogeneity and functional diversity is still poorly understood. Driven by the resolving power of single-cell transcriptomics, several recent studies provided new insights into the cellular complexity of ASPCs among different mammalian fat depots. In this review, we present current knowledge on ASPCs, their population structure, hierarchy, fat depot-specific nature, function, and regulatory mechanisms, and discuss not only the similarities, but also the differences between mouse and human ASPC biology.

Long-term outcomes of omentum-preserving versus resecting gastrectomy for locally advanced gastric cancer with propensity score analysis

Omentectomy is conducted for advanced gastric cancer (AGC) patients as radical surgery without an adequate discussion of the effect. This study was conducted to reveal the impact of omentum-preserving gastrectomy on postoperative outcomes. AGC patients with cT3 and 4 disease who underwent total or distal gastrectomy with R0 resection were identified retrospectively. They were divided into the omentum-preserved group (OPG) and the omentum-resected group (ORG) and matched with propensity score matching with multiple imputation for missing values. Three-year overall survival (OS) and 3-year relapse-free survival (RFS) were compared, and the first recurrence site and complications were analysed. The numbers of eligible patients were 94 in the OPG and 144 in the ORG, and after matching, the number was 73 in each group. No significant difference was found in the 3-year OS rate (OPG: 78.9 vs. ORG: 78.9, P = 0.54) or the 3-year RFS rate (OPG: 77.8 vs. ORG: 68.2, P = 0.24). The proportions of peritoneal carcinomatosis and peritoneal dissemination as the first recurrence site and the rate and severity of complications were similar in the two groups. Omentectomy is not required for radical gastrectomy for AGC.

Omental macrophages secrete chemokine ligands that promote ovarian cancer colonization of the omentum via CCR1

The omentum is the most common site of ovarian cancer metastasis. Immune cell clusters called milky spots are found throughout the omentum. It is however unknown if these immune cells contribute to ovarian cancer metastasis. Here we report that omental macrophages promote the migration and colonization of ovarian cancer cells to the omentum through the secretion of chemokine ligands that interact with chemokine receptor 1 (CCR1). We found that depletion of macrophages reduces ovarian cancer colonization of the omentum. RNA-sequencing of macrophages isolated from mouse omentum and mesenteric adipose tissue revealed a specific enrichment of chemokine ligand CCL6 in omental macrophages. CCL6 and the human homolog CCL23 were both necessary and sufficient to promote ovarian cancer migration by activating ERK1/2 and PI3K pathways. Importantly, inhibition of CCR1 reduced ovarian cancer colonization. These findings demonstrate a critical mechanism of omental macrophage induced colonization by ovarian cancer cells via CCR1 signaling.

Krishnan et al. find that CCR1 ligands CCL6 and CCL23 secreted by murine and human macrophages, respectively, enhance metastatic colonization of ovarian cancer cells to the omentum in manner dependent on chemokine receptor 1 (CCR1). This study suggests that targeting CCR1 or CCL23 in ovarian cancer may be a therapeutic strategy.

Epithelial Ovarian Cancer and the Immune System: Biology, Interactions, Challenges and Potential Advances for Immunotherapy

Recent advances in the understanding of immune function and the interactions with tumour cells have led to the development of various cancer immunotherapies and strategies for specific cancer types. However, despite some stunning successes with some malignancies such as melanomas and lung cancer, most patients receive little or no benefit from immunotherapy, which has been attributed to the tumour microenvironment and immune evasion. Although the US Food and Drug Administration have approved immunotherapies for some cancers, to date, only the anti-angiogenic antibody bevacizumab is approved for the treatment of epithelial ovarian cancer. Immunotherapeutic strategies for ovarian cancer are still under development and being tested in numerous clinical trials. A detailed understanding of the interactions between cancer and the immune system is vital for optimisation of immunotherapies either alone or when combined with chemotherapy and other therapies. This article, in two main parts, provides an overview of: (1) components of the normal immune system and current knowledge regarding tumour immunology, biology and their interactions; (2) strategies, and targets, together with challenges and potential innovative approaches for cancer immunotherapy, with attention given to epithelial ovarian cancer.

Risk of Omental Metastases in Patients Undergoing Cytoreductive Surgery for Colorectal Peritoneal Metastases

BACKGROUND

Complete cytoreductive surgery of macroscopic tumor is a potentially curative treatment for patients with colorectal peritoneal metastases.

OBJECTIVE

This study aims to determine the risk of microscopic tumor involvement of the greater omentum in patients with normal-looking omentum at the time of cytoreductive surgery for colorectal peritoneal metastases.

DESIGN

This was a cohort study.

SETTINGS

The prospective BIG-RENAPE database (NCT02823860) was analyzed.

PATIENTS

All patients who underwent a complete cytoreductive surgery with greater omentectomy for colorectal peritoneal metastases at a single institution between January 2005 and December 2017 were included.

MAIN OUTCOME MEASURE

Data regarding involvement of the greater omentum were extracted from surgical and pathological records.

RESULTS

Of 337 patients who underwent cytoreductive surgery for colorectal peritoneal metastases, 241 (71.51%) presented macroscopic omental invasion. Among the 96 patients who underwent a complete cytoreductive surgery with no macroscopic evidence of disease in the greater omentum during surgical exploration, 17 patients (17.70%) had microscopic evidence of tumor in the omentum. Patients with pathological evidence of omental tumor involvement were more likely to have a higher peritoneal cancer index (median 9 vs 4, p = 0.006).

LIMITATIONS

No survival analysis could be provided regarding the impact of omentectomy.

CONCLUSION

In patients with a normal-looking omentum during surgery for colorectal peritoneal metastases, microscopic tumor was present in 17%. Routine greater omentectomy should be considered in these patients to ensure complete cytoreduction. See Video Abstract at http://links.lww.com/DCR/B262.ClinicalTrials.gov Identifier: NCT02823860 RIESGO DE METÁSTASIS OMENTALES EN PACIENTES SOMETIDOS A CIRUGÍA CITORREDUCTORA, POR METÁSTASIS PERITONEALES COLORRECTALES: La cirugía citorreductora completa del tumor macroscópico, es un tratamiento potencialmente curativo, en pacientes con metástasis peritoneales colorrectales.Determinar el riesgo de afectación tumoral microscópica del epiplón mayor, en pacientes con epiplón de aspecto normal, al momento de la cirugía citorreductora por metástasis peritoneales colorrectales.Este fue un estudio de cohorte.Se analizó la base de datos prospectiva BIG-RENAPE (NCT02823860).Se incluyeron a todos los pacientes sometidos a una cirugía citorreductora completa con omentectomía mayor, por metástasis peritoneales colorrectales, de una sola institución, entre enero de 2005 y diciembre de 2017.Se extrajeron los datos de la afectación del epiplón mayor, de los registros quirúrgicos y patológicos.De 337 pacientes sometidos a cirugía citorreductora por metástasis peritoneales colorrectales, 241 (71.51%) presentaron invasión omental macroscópica. Entre los 96 pacientes sometidos a cirugía citorreductora completa, sin evidencia macroscópica de enfermedad en el epiplón mayor, durante la exploración quirúrgica, 17 pacientes (17,70%) tuvieron en el epiplón, evidencia microscópica de tumor. Los pacientes con evidencia patológica de afectación del tumor omental, fueron más propensos a tener un índice de cáncer peritoneal más alto (mediana 9 frente a 4, p = 0,006).No se pudo obtener ningún análisis de supervivencia, sobre el impacto de la omentectomía.En pacientes con epiplón de aspecto normal, durante la cirugía por metástasis peritoneales colorrectales, estuvo presente el tumor microscópico, en el 17% de los casos. Se debe considerar una omentectomía mayor de rutina en estos pacientes, para asegurar una citorreducción completa. Consulte Video Resumen http://links.lww.com/DCR/B262.Identificador de ClinicalTrials.gov: NCT02823860.

The Contribution of the Omentum to the Outcome From Sepsis: An Experimental Animal Study

The omentum is a large mesenchymal fibro-fatty tissue with remarkable healing capability. It is also rich in immune cells, including macrophages and lymphocytes, within particular structures named milky spots. Clinical observations indicate a high incidence of peritonitis after the removal of the omentum suggesting that it may play a role in sepsis. To test this possibility, male CD-1 mice underwent simultaneous omentectomy and cecal ligation and puncture (CLP), omentectomy-sham operation and CLP alone, and mortality was documented within 72 h post the insults. A significant increase in mortality was observed in mice subjected to omentectomy and CLP in comparison with CLP alone. Mortality was correlated with an increase in cytokine gene expression within the lung after omentectomy and CLP as opposed to CLP alone. However, no differences in bacterial load were observed within the peritoneum or blood between groups. To test the long-term effect of omentectomy, mice were subjected to omentum removal or sham operation, allowed to recover from surgery for 14 or 28 days, and then both were subjected to CLP. In these cases, no differences in mortality were observed between the groups suggesting that the lack of omentum triggers a compensatory mechanism. Finally, omentectomy and sham operation altered the composition of peritoneal immune cells with the disappearance of F4/80 macrophages and the appearance of a new population of F4/80 macrophages within 1 or 14 days post-surgery. The F4/80 positive cells reappeared after 28 days following the procedures. All of these observations suggest that the omentum plays an early role in the outcome from sepsis.

Neutrophils in Tuberculosis-Associated Inflammation and Lung Pathology

Protective immunity to Mycobacterium tuberculosis (Mtb)—the causative agent of tuberculosis (TB)—is not fully understood but involves immune responses within the pulmonary airways which can lead to exacerbated inflammation and immune pathology. In humans, this inflammation results in lung damage; the extent of which depends on specific host pro-inflammatory processes. Neutrophils, though increasingly linked to the development of inflammatory disorders, have been less well studied in relation to TB-induced lung pathology. Neutrophils mode of action and their specialized functions can be directly linked to TB-specific lung tissue damage observed on patient chest X-rays at diagnosis and contribute to long-term pulmonary sequelae. This review discusses aspects of neutrophil activity associated with active TB, including the resulting inflammation and pulmonary impairment. It highlights the significance of neutrophil function on TB disease outcome and underlines the necessity of monitoring neutrophil function for better assessment of the immune response and severity of lung pathology associated with TB. Finally, we propose that some MMPs, ROS, MPO, S100A8/A9 and Glutathione are neutrophil-related inflammatory mediators with promising potential as targets for developing host-directed therapies for TB.

Current insights into the metastasis of epithelial ovarian cancer - hopes and hurdles

BACKGROUND

Ovarian cancer is the most lethal gynecologic cancer and the fifth leading cause of cancer-related mortality in women worldwide. Despite various attempts to improve the diagnosis and therapy of ovarian cancer patients, the survival rate for these patients is still dismal, mainly because most of them are diagnosed at a late stage. Up to 90% of ovarian cancers arise from neoplastic transformation of ovarian surface epithelial cells, and are usually referred to as epithelial ovarian cancer (EOC). Unlike most human cancers, which are disseminated through blood-borne metastatic routes, EOC has traditionally been thought to be disseminated through direct migration of ovarian tumor cells to the peritoneal cavity and omentum via peritoneal fluid. It has recently been shown, however, that EOC can also be disseminated through blood-borne metastatic routes, challenging previous thoughts about ovarian cancer metastasis.

CONCLUSIONS

Here, we review our current understanding of the most updated cellular and molecular mechanisms underlying EOC metastasis and discuss in more detail two main metastatic routes of EOC, i.e., transcoelomic metastasis and hematogenous metastasis. The emerging concept of blood-borne EOC metastasis has led to exploration of the significance of circulating tumor cells (CTCs) as novel and non-invasive prognostic markers in this daunting cancer. We also evaluate the role of tumor stroma, including cancer associated fibroblasts (CAFs), tumor associated macrophages (TAMs), endothelial cells, adipocytes, dendritic cells and extracellular matrix (ECM) components in EOC growth and metastasis. Lastly, we discuss therapeutic approaches for targeting EOC. Unraveling the mechanisms underlying EOC metastasis will open up avenues to the design of new therapeutic options. For instance, understanding the molecular mechanisms involved in the hematogenous metastasis of EOC, the biology of CTCs, and the detailed mechanisms through which EOC cells take advantage of stromal cells may help to find new opportunities for targeting EOC metastasis.

The Greater Omentum-A Vibrant and Enigmatic Immunologic Organ Involved in Injury and Infection Resolution

Once thought of as an inert fatty tissue present only to provide insulation for the peritoneal cavity, the omentum is currently recognized as a vibrant immunologic organ with a complex structure uniquely suited for defense against pathogens and injury. The omentum is a source of resident inflammatory and stem cells available to participate in the local control of infection, wound healing, and tissue regeneration. It is intimately connected with the systemic vasculature and communicates with the central nervous system and the hypothalamic pituitary adrenal axis. Furthermore, the omentum has the ability to transit the peritoneal cavity and sequester areas of inflammation and injury. It contains functional, immunologic units commonly referred to as "milky spots" that contribute to the organ's immune response. These milky spots are complex nodules consisting of macrophages and interspersed lymphocytes, which are gateways for the infiltration of inflammatory cells into the peritoneal cavity in response to infection and injury. The omentum contains far greater complexity than is currently conceptualized in clinical practice and investigations directed at unlocking its beneficial potential may reveal new mechanisms underlying its vital functions and the secondary impact of omentectomy for the staging and treatment of a variety of diseases.

Nonproliferative and Proliferative Lesions of the Rat and Mouse Hematolymphoid System

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative changes in rats and mice. The purpose of this publication is to provide a standardized nomenclature for classifying changes observed in the hematolymphoid organs, including the bone marrow, thymus, spleen, lymph nodes, mucosa-associated lymphoid tissues, and other lymphoid tissues (serosa-associated lymphoid clusters and tertiary lymphoid structures) with color photomicrographs illustrating examples of the lesions. Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. The nomenclature for these organs is divided into 3 terminologies: descriptive, conventional, and enhanced. Three terms are listed for each diagnosis. The rationale for this approach and guidance for its application to toxicologic pathology are described in detail below.

Epigenetic Therapy as a Putative Molecular Target to Modulate B Cell Biology and Behavior in the Context of Immunological Disorders

Histone Deacetylase- (HDAC-) dependent epigenetic mechanisms have been widely explored in the last decade in different types of malignancies in preclinical studies. This effort led to the discovery and development of a range of new HDAC inhibitors (iHDAC) with different chemical properties and selective abilities. In fact, hematological malignancies were the first ones to have new iHDACs approved for clinical use, such as Vorinostat and Romidepsin for cutaneous T cell lymphoma and panobinostat for multiple myeloma. Besides these promising already approved iHDACs, we highlight a range of studies focusing on the HDAC-dependent epigenetic control of B cell development, behavior, and/or function. Here, we highlight 21 iHDACs which have been studied in the literature in the context of B cell development and/or dysfunction mostly focused on B cell lymphomagenesis. Regardless, we have identified 55 clinical trials using 6 out of 21 iHDACs to approach their putative roles on B cell malignancies; none of them focuses on peritoneal B cell populations. Since cells belonging to this peculiar body compartment, named B1 cells, may contribute to the development of autoimmune pathologies, such as lupus, a better understanding of the HDAC-dependent epigenetic mechanisms that control its biology and behavior might shed light on iHDAC use to manage these immunological dysfunctions. In this sense, iHDACs might emerge as a promising new approach for translational studies in this field. In this review, we discuss a putative role of iHDACs in the modulation of peritoneal B cell subpopulation's balance as well as their role as therapeutic agents in the context of chronic diseases mediated by peritoneal B cells.

Cytokine TNF-α promotes invasion and metastasis of gastric cancer by down-regulating Pentraxin3

As a novel multifaceted player in cancer, Pentraxin3(PTX3) was recognized to be a possible factor related with tumor development. Recent researches have indicated that PTX3 is involved in immune response, inflammation, as well as cancer, and is greatly controlled by numerous cytokines. Tumor necrosis factor (TNF-α) is an imperative cytokine that demonstrates an extensive array of biological consequences in gastric cancer advancement. Here, we inspected the expression of PTX3 in gastric carcinoma tissues along with gastric cell lines and established that PTX3 was suggestively inferior in gastric cancer tissue and cells. The treatment of the gastric cell lines BGC-823 as well as SGC-7901 with rhTNF-α caused substantial decrease in the expression of PTX3. Furthermore, PTX3 controlled the capability of cell migration, invasion as well as epithelial-mesenchymal transition (EMT) in gastric cancer cell lines mediated by TNF-α. Additionally, PTX3 upregulation inhibited tumorigenicity in vivo and could be reversed by exogenous TNF-α. Conversely, overexpression of PTX3 inhibited progress both in vitro as well as in vivo in gastric cancer mediated by TNF-α. Further studies are necessary to demonstrate the mechanism of interaction between PTX3 and cytokines.

Roles of omental and bone marrow adipocytes in tumor biology

Accumulating evidence highlights the importance of interactions between tumour cells and stromal cells for tumour initiation, progression, and metastasis. In tumours that contain adipocyte in their stroma, adipocytes contribute to modification of tumour microenvironment and affect metabolism of tumour and tumour progression by production of cytokines and adipokines from the lipids. The omentum and bone marrow (BM) are highly adipocyte-rich and are also common metastatic and primary tumour developmental sites. Omental adipocytes exhibit metabolic cross-talk, immune modulation, and angiogenesis. BM adipocytes secrete adipokines, and participate in solid tumour metastasis through regulation of the CCL2/CCR2 axis and metabolic interactions. BM adipocytes also contribute to the progression of hematopoietic neoplasms. Here, we here provide an overview of research progress on the cross-talks between omental/BM adipocytes and tumour cells, which may be pivotal modulators of tumour biology, thus highlighting novel therapeutic targets.

Abbreviations: MCP-1, monocyte chemoattractant protein 1IL, interleukinSTAT3, signal transducer and activator of transcription 3FABP4, fatty acid binding protein 4PI3K/AKT, phosphoinositide 3-kinase/protein kinase BPPAR, peroxisome proliferator-activated receptorPUFA, polyunsaturated fatty acidTAM, tumour-associated macrophagesVEGF, vascular endothelial growth factorVEGFR, vascular endothelial growth factor receptorBM, bone marrowBMA, bone marrow adipocytesrBMA, regulated BMAcBMA, constitutive BMAUCP-1, uncoupling protein-1TNF-α, tumour necrosis factor-alphaRANKL, receptor activator of nuclear factor kappa-Β ligandVCAM-1, vascular cell adhesion molecule 1JAK2, Janus kinase 2CXCL (C–X–C motif) ligandPGE2, prostaglandin E2COX-2, cyclooxygenase-2CCL2, C-C motif chemokine ligand 2NF-κB, nuclear factor-kappa BMM, multiple myelomaALL, acute lymphoblastic leukemiaAML, acute myeloid leukemiaGDF15, growth differentiation factor 15AMPK, AMP-activated protein kinaseMAPK, mitogen-activated protein kinaseAPL, acute promyelocytic leukemiaCCR2, C-C motif chemokine receptor 2SDF-1α, stromal cell-derived factor-1 alphaFFA, free fatty acidsLPrA, leptin peptide receptor antagonistMCD, malonyl-CoA decarboxylase.

Foliate Lymphoid Aggregates as Novel Forms of Serous Lymphocyte Entry Sites of Peritoneal B Cells and High-Grade B Cell Lymphomas

The cellular homeostasis of lymphoid tissues is determined by the continuous interactions of mobile hematopoietic cells within specialized microenvironments created by sessile stromal cells. In contrast to the lymph nodes and mucosal lymphoid tissues with well-defined entry and exit routes, the movement of leukocytes in the peritoneal cavity is largely unknown. In this study, we report that, in addition to the omental milky spots and fat-associated lymphoid clusters, in mice, the serous surface of the mesenteric adipose streaks contains lymphocyte-rich organoids comprised of a highly compacted leaf-like part connected to the adipose tissue that can also efficiently bind B cells and high-grade B cell lymphoma (diffuse large B cell lymphoma) cells. Denoted as foliate lymphoid aggregates (FLAgs), these structures show incomplete T/B segregation and a partially differentiated stromal architecture. LYVE-1-positive macrophages covering FLAgs efficiently bind i.p. injected normal B cells as well as different types of diffuse large B cell lymphoma cells. Within FLAgs, the lymphocytes compartmentalize according to their chemokine receptor pattern and subsequently migrate toward the mesenteric lymph nodes via the mesenteric lymphatic capillaries. The blood supply of FLAgs includes short vascular segments displaying peripheral lymph node addressin, and the extravasation of lymphocytes to the omental and mesenteric adipose tissues is partly mediated by L-selectin. The appearance of i.p. injected cells in mesenteric lymph nodes suggests that the mesentery-associated lymphatics may also collect leukocytes from the fat-associated lymphoid clusters and FLAgs, thus combining the mucosal and serous exit of mobile leukocytes and increasing the range of drainage sites for the peritoneal expansion of lymphoid malignancies.

Role of Cancer-Associated Fibroblast in Gastric Cancer Progression and Resistance to Treatments

Although the survival of gastric cancer (GC) patients has gradually improved, the outcomes of advanced GC patients remain unsatisfactory despite standard treatment with conventional chemotherapy or targeted agents. Several studies have shown that cancer-associated fibroblasts (CAFs), a major component of tumor stroma in GC, may have significant roles in GC progression and resistance to treatments. CAFs are a major source of various secreted molecules in the tumor microenvironment, which stimulate cancer cells and other noncancerous components of GC. Surprisingly, these factors could be involved in gastric carcinogenesis. Cytokines, including interleukin-6 and interleukin-11, or growth factors, such as fibroblast growth factor produced from CAFs, can directly activate GC cells and consequently lead to the development of an aggressive phenotype. Galectin-1 or hepatocyte growth factor can be involved in CAF-derived neovascularization in GC. In addition, recent studies showed that CAFs can affect tumor immunity through M2 polarization of tumor-associated macrophages. Finally, the current study aimed to introduce several inhibitory agents and evaluate their suppressive effects on CAFs in patients with GC progression. However, further studies are required to evaluate their safety and select appropriate patients for application in clinical settings.

Pressurized intraperitoneal aerosol chemotherapy and its effect on gastric-cancer-derived peritoneal metastases: an overview

This manuscript aspires to portray a review of the current literature focusing on manifest peritoneal metastasis (PM) derived from gastric cancer and its treatment options. Despite the development of chemotherapy and multimodal treatment options during the last decades, mortality remains high worldwide. After refreshing important epidemiological considerations, the molecular mechanisms currently accepted through which PM occurs are revised. Palliative chemotherapy is the only recommended treatment option for patients with PM of gastric cancer according to the National Comprehensive Cancer Network guidelines, although cytoreductive surgery in combination with hyperthermic intraperitoneal chemotherapy demonstrated promising results in selected patients with regional PM and localized intraabdominal tumor spread. A novel treatment named pressurized intraperitoneal aerosol chemotherapy may have a promising future in improving overall survival with an acceptable postoperative complication rate and stabilizing quality of life during treatment. Additionally, the procedure has been proved to be safe for the patient and medical personnel and a feasible, repeatable method to deter metastatic proliferation. This overview comprehensively addresses this novel and promising treatment in the context of a scientifically and clinically challenging disease.

An evolving story of the metastatic voyage of ovarian cancer cells: cellular and molecular orchestration of the adipose-rich metastatic microenvironment

Metastasis is a complex multistep process that involves critical interactions between cancer cells and a variety of stromal components in the tumor microenvironment, which profoundly influence the different aspects of the metastatic cascade and organ tropism of disseminating cancer cells. Ovarian cancer is the most lethal gynecological malignancy and is characterized by peritoneal disseminated metastasis. Evidence has demonstrated that ovarian cancer possesses specific metastatic tropism for the adipose-rich omentum, which has a pivotal role in the creation of the metastatic tumor microenvironment in the intraperitoneal cavity. Considering the distinct biology of ovarian cancer metastasis, the elucidation of the cellular and molecular mechanisms underlying the reciprocal interplay between ovarian cancer cells and surrounding stromal cell types in the adipose-rich metastatic microenvironment will provide further insights into the development of novel therapeutic approaches for patients with advanced ovarian cancer. Herein, we review the biological mechanisms that regulate the highly orchestrated crosstalk between ovarian cancer cells and various cancer-associated stromal cells in the metastatic tumor microenvironment with regard to the omentum by illustrating how different stromal cells concertedly contribute to the development of ovarian cancer metastasis and metastatic tropism for the omentum.

Stimulation of Peritoneal Mesothelial Cells to Secrete Matrix Metalloproteinase-9 (MMP-9) by TNF-α: A Role in the Invasion of Gastric Carcinoma Cells

It has recently been recognized that inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), upregulate the secretion of matrix metalloproteinase-9 (MMP-9) from cancer cells and thereby promote peritoneal dissemination. In this study, we found that TNF-α also stimulated peritoneal mesothelial cells to secrete MMP-9 as assessed by zymography. MMP-9 gene expression in mesothelial cells induced by TNF-α was confirmed by quantitative RT-PCR analysis. We then utilized the reconstituted artificial mesothelium, which was composed of a monolayer of mesothelial cells cultured on a Matrigel layer in a Boyden chamber system, to examine the effects of TNF-α on carcinoma cell invasion. The transmigration of MKN1 human gastric carcinoma cells through the reconstituted mesothelium was promoted by TNF-α in a dose-dependent manner. The increased MKN1 cell migration was partially inhibited by the anti-α3 integrin antibody, indicating that the invasion process involves an integrin-dependent mechanism. Finally, we observed that the invasion of MMP-9-knockdown MKN1 cells into Matrigel membranes was potentiated by the exogenous addition of purified proMMP-9. These results suggest that TNF-α-induced MMP-9 secretion from mesothelial cells plays an important role in the metastatic dissemination of gastric cancer.

Stromal fibroblast activation protein alpha promotes gastric cancer progression via epithelial-mesenchymal transition through Wnt/ β-catenin pathway

BACKGROUND

To investigate the influence of fibroblast activation protein alpha (FAP) derived from cancer-associated fibroblasts (CAFs), as well as potential mechanism of epithelial mesenchymal transition (EMT), on gastric cancer (GC) progression.

METHODS

Correlation between CAFs-derived FAP and clinical results has been studied by using 60 GC cases. To confirm this relationship, SGC7901 cells were co-cultured with pre-established FAP-overexpressed fibroblasts in vitro and the characteristics including proliferation, migration, invasion and apoptosis abilities were detected subsequently. Meanwhile, SGC and GES1 cells cocultured with FAP-overexpressed fibroblasts were treated with cis-platinum for apoptotic analysis. The underlying EMT was detected by analyzing expression level of E-cadherin, ZO-1, N-cadherin, Vimentin, α-SMA, DKK1 and LEF-1 through western blot and immunofluorescence staining assay. Finally, the tumor-promoting ability of FAP was investigated by utlizing a xenograft gastric cancer nude mouse model.

RESULTS

It show that FAP has a high-risk correlation with the malignant level of clinical outcomes in GC patients. FAP promotes the ability of proliferation, migration, invasion, apoptosis-inhibition of SGC7901 cells and induces apoptosis of GES1 cells in vitro. The mechanism study shows that epithelial markers have been down-regulated and mesenchymal markers and Wnt/β-catenin signal pathway related proteins have been up-regulated. Animal assay suggests that tumor burden has been enhanced by FAP significantly in vivo.

CONCLUSIONS

Stromal FAP could be a potential prognostic biomarker in GC by promoting cancer progression via EMT through Wnt/ β-catenin signal pathway.

Evitar (l-Alanyl-l-Glutamine) Regulates Key Signaling Molecules in the Pathogenesis of Postoperative Tissue Fibrosis

Aims:

Hypoxia and the resulting oxidative stress play a major role in postoperative tissue fibrosis. The objective of this study was to determine the effect of l-alanyl-l-glutamine (Ala-Gln) on key markers of postoperative tissue fibrosis: hypoxia-inducible factor (HIF) 1α and type I collagen.

Methods:

Primary cultures of human normal peritoneal fibroblasts (NPF) established from normal peritoneal tissue were treated with increasing doses of Ala-Gln (0, 1, 2, or 10 mM) with hypoxia ([2% O2] 0-48 hours; continuous hypoxia) or after hypoxia (0.5, 1, 2, 4 hours) and restoration of normoxia (episodic hypoxia) with immediate treatment with Ala-Gln. Hypoxia-inducible factor 1α and type 1 collagen levels were determined by enzyme-linked immunosorbent assay. Data were analyzed with 1-way analysis of variance followed by Tukey tests with Bonferroni correction.

Results:

Hypoxia-inducible factor 1α and type I collagen levels increased in untreated controls by 3- to 4-fold in response to continuous and episodic hypoxia in human NPF. Under continuous hypoxia, HIF-1α and type I collagen levels were suppressed by Ala-Gln in a dose-dependent manner. l-alanyl-l-glutamine treatment after episodic hypoxia also suppressed HIF-1α and type I collagen levels for up to 24 hours for all doses and up to 48 hours at the highest dose, regardless of exposure time to hypoxia.

Conclusions:

l-alanyl-l-glutamine significantly suppressed hypoxia-induced levels of key tissue fibrosis (adhesion) phenotype markers under conditions of continuous as well as episodic hypoxia in vitro. This effect of glutamine on molecular events involved in the cellular response to insult or injury suggests potential therapeutic value for glutamine in the prevention of postoperative tissue fibrosis.