Mechanisms of peritoneal dissemination in gastric cancer

Prediction of peritoneal free cancer cells in gastric cancer patients by golden-angle radial sampling dynamic contrast-enhanced magnetic resonance imaging

OBJECTIVES

Peritoneal free cancer cells can negatively impact disease progression and patient outcomes in gastric cancer. This study aimed to investigate the feasibility of using golden-angle radial sampling dynamic contrast-enhanced magnetic resonance imaging (GRASP DCE-MRI) to predict the presence of peritoneal free cancer cells in gastric cancer patients.

METHODS

All enrolled patients were consecutively divided into analysis and validation groups. Preoperative magnetic resonance imaging (MRI) scans and perfusion were performed in patients with gastric cancer undergoing surgery, and peritoneal lavage specimens were collected for examination. Based on the peritoneal lavage cytology (PLC) results, patients were divided into negative and positive lavage fluid groups. The data collected included clinical and MR information. A nomogram prediction model was constructed to predict the positive rate of peritoneal lavage fluid, and the validity of the model was verified based on data from the verification group.

RESULTS

There was no statistical difference between the proportion of PLC-positive cases predicted by GRASP DCE-MR and the actual PLC test. MR tumor stage, tumor thickness, and perfusion parameter Tofts-Ketty model volume transfer constant (Ktrans) were independent predictors of positive peritoneal lavage fluid. The nomogram model featured a concordance index (C-index) of 0.785 and 0.742 for the modeling and validation groups, respectively.

CONCLUSIONS

GRASP DCE-MR could effectively predict peritoneal free cancer cells in gastric cancer patients. The nomogram model constructed using these predictors may help clinicians to better predict the risk of peritoneal free cancer cells being present in gastric cancer patients.

Primary omental smooth muscle tumor in an adult male: a diagnostic dilemma for leiomyoma: a case report

BACKGROUND

The greater omentum comprises peritoneal, adipose, vascular, and lymphoid tissues. Most omental malignancies are metastatic tumors, and the incidence of primary tumors is rare. We report on a prior omental smooth muscle tumor case in an adult male patient.

CASE PRESENTATION

A 54-year-old Japanese male patient with no relevant medical history was diagnosed with an abdominal mass during a routine medical checkup. Subsequent contrast-enhanced computed tomography revealed a mass of approximately 3 cm in size in the greater omentum, and a laparotomy was performed. A 27 × 25 × 20 mm raised lesion was found in the omentum. Microscopically, spindle cells were observed and arranged in whorls and fascicles. Individual tumor cells had short spindle-shaped nuclei with slightly increased chromatin and were characterized by a slightly eosinophilic, spindle-shaped cytoplasm. The mitotic count was less than 1 per 50 high-power fields. The tumor cells showed positive immunoreactivity for α smooth muscle actin, HHF35, and desmin on immunohistochemical examination. The Ki-67 labeling index using the average method was 1.76% (261/14806). No immunoreactivity was observed for any of the other tested markers. We considered leiomyoma owing to a lack of malignant findings. However, primary omental leiomyoma has rarely been reported, and it can be difficult to completely rule out the malignant potential of smooth muscle tumors in soft tissues. Our patient was decisively diagnosed with a primary omental smooth muscle tumor considering leiomyoma. Consequently, the patient did not undergo additional adjuvant therapy and was followed up. The patient was satisfied with treatment and showed neither recurrence nor metastasis at the 13-month postoperative follow-up.

DISCUSSION AND CONCLUSION

We encountered a primary smooth muscle tumor of the greater omentum with no histological findings suggestive of malignancy in an adult male patient. However, omental smooth muscle tumors are extremely difficult to define as benign, requiring careful diagnosis. Further case reports with long-term follow-up and case series are required to determine whether a true omental benign smooth muscle tumor (leiomyoma) exists. In addition, proper interpretation of the Ki-67 labeling index should be established. This case study is a foundation for future research.

Intraperitoneal transfer of microRNA-29b-containing small extracellular vesicles can suppress peritoneal metastases of gastric cancer

Small extracellular vesicles (sEV) contain various microRNAs (miRNAs) and play crucial roles in the tumor metastatic process. Although miR-29b levels in peritoneal exosomes were markedly reduced in patients with peritoneal metastases (PM), their role has not been fully clarified. In this study, we asked whether the replacement of miR-29b can affect the development of PM in a murine model. UE6E7T-12, human bone marrow-derived mesenchymal stem cells (BMSCs), were transfected with miR-29b-integrating recombinant lentiviral vector and sEV were isolated from culture supernatants using ultracentrifugation. The sEV contained markedly increased amounts of miR-29b compared with negative controls. Treatment with transforming growth factor-β1 decreased the expression of E-cadherin and calretinin with increased expression of vimentin and fibronectin on human omental tissue-derived mesothelial cells (HPMCs). However, the effects were totally abrogated by adding miR-29b-rich sEV. The sEV inhibited proliferation and migration of HPMCs by 15% (p < 0.005, n = 6) and 70% (p < 0.005, n = 6), respectively, and inhibited adhesion of NUGC-4 and MKN45 to HPMCs by 90% (p < 0.0001, n = 5) and 77% (p < 0.0001, n = 5), respectively. MicroRNA-29b-rich murine sEV were similarly obtained using mouse BMSCs and examined for in vivo effects with a syngeneic murine model using YTN16P, a highly metastatic clone of gastric cancer cell. Intraperitoneal (IP) transfer of the sEV every 3 days markedly reduced the number of PM from YTN16P in the mesentery (p < 0.05, n = 6) and the omentum (p < 0.05, n = 6). Bone marrow mesenchymal stem cell-derived sEV are a useful carrier for IP administration of miR-29b, which can suppress the development of PM of gastric cancer.

Gastric cancer clinical characteristics and their altered trends in South China: An epidemiological study with 2,800 cases spanning 26 years

BACKGROUND

Gastric cancer (GC) is a serious threat to human health. The clinical GC characteristics in China may be impacted by changes in people's lifestyles and the promotion of early GC (EGC) screening. The present study aims to evaluate the recent trends of GC characteristics in South China and search for hazardous factors limiting the survival time of GC patients.

METHODS

Data on GC patients that were hospitalized in the Department of Digestive Center, the First Affiliated Hospital, Sun Yat-sen University, from 1994 to 2019 were collected and divided into two categories according to the time when the EGC screening began in China: the PRE group (previous 13 years, 1994-2006) and the PAS group (past 13 years, 2007-2019).

RESULTS

We found that, although the 5-year survival rate increased in the PAS group compared with the PRE group (P < 0.0001), patients with age ≥60 years or Borrmann type IV still had a worse prognosis. In the PAS group, the larger percentages of elderly patients and patients with Borrmann type IV in the lymphatic metastases (N1) group (41.0% vs. 51.1%, P = 0.0014) and stage IV subgroup (20.7% vs. 32.2%, P = 0.016), respectively, when compared with the PRE group, may have contributed to the poor outcome of GC. By comparing the odds ratio (OR) of 5-year overall survival (OS) in the two 13-year periods, female sex and T2 turned into risk factors because of a greater proportion of Borrmann type IV or elderly patients in the PAS group (OR = 0.983, 95% CI = 0.723-1.336 vs. OR = 1.277, 95% CI = 1.028-1.586 and OR = 1.545, 95% CI = 0.499-4.775 vs. OR = 2.227, 95% CI = 1.124-4.271, respectively).

CONCLUSIONS

Despite the GC epidemiology changes, the overall prognosis of GC patients has improved in South China. However, old age and Borrmann type IV are still the major restrictions affecting the survival of GC patients, a situation which calls for additional attention.

Practical nomogram based on comprehensive CT texture analysis to preoperatively predict peritoneal occult metastasis of gastric cancer patients

Objectives

This study aims to evaluate whether a nomogram based on comprehensive CT texture analysis of primary tumor and peritoneotome combined with conventional CT signs can preoperatively predict peritoneal occult metastasis in gastric cancer patients.

Methods

A total of 1,251 patients with gastric cancer (GC) were retrospectively analyzed in Fujian Province Hospital between 2008 and 2020. Patients from the occult peritoneal metastasis (PM) group were initially diagnosed as PM-negative on CT and later confirmed as PM-positive through laparoscopy or surgery. The group without PM was randomly sampled from patients without PM. The preoperative CT signs and texture features and clinical characteristics of patients were retrospectively analyzed. Hazard factors of occult PM were identified by univariate analysis and multivariate logistic regression analysis, which were intended for creating prediction models. A nomogram was established based on the model with the highest predictive efficacy and clinical application value.

Results

A total of 31 patients with occult PM and 165 patients without PM were enrolled in this study. The maximum size, thickness, enhancement, serous involvement of primary GC tumor and ascites on CT, and texture features such as inhomogeneity of the primary tumor, standard deviation, and inhomogeneity of the peritoneum were determined as independent predictors that could be jointly applied to predict occult PM. We separately constructed five forecast models using CT signs, primary tumor texture, peritoneum texture, primary tumor texture + peritoneum texture, and their combination for predicting occult PM. These five prediction models achieved an AUC value of 0.832, 0.70, 0.784, 0.838, and 0.941, respectively. The DeLong test and Decision Curve Analysis (DCA) showed that the joint model, containing three meaningful CT signs (maximum size, thickness, and ascites) and two meaningful texture parameters (inhomogeneity of the primary tumor and inhomogeneity of the peritoneum), possessed the best predictive performance and clinical application (p&lt;0.05). A forecast nomogram was subsequently established from the model above-mentioned. The calibration curves of the nomogram indicated a good consistency (a concordance index of 0.807) between the projection and the actual observation of occult PM.

Conclusions

A practical projection nomogram based on the comprehensive CT texture analysis of a primary tumor and peritoneotome combined with conventional CT signs was constructed in our study, which can be conveniently used in preoperative personalized prediction of occult PM for GC patients, and acts as a recommendation for the optimization of clinical management.

Adipocytes contribute to tumor progression and invasion of peritoneal metastasis by interacting with gastric cancer cells as cancer associated fibroblasts

BACKGROUND

Peritoneal metastasis (PM) is one of the most common causes of noncurative surgery and the most frequent recurrence pattern in gastric cancer (GC). During the process of PM, GC cells detached from primary tumor interact with human peritoneal mesothelial cells (HPMC) overlapped with adipose tissues such as the omentum or mesentery. Although the interaction with HPMC promotes the malignancy of GC, the role of adipose tissues remains unclear.

AIMS

We aimed to clarify how adipose tissue are affected by adjacent primary tumors during the expression of adipokines and to elucidate whether GC cells transform adipocytes into CAFs in vitro. In addition, we investigated whether GC cells are affected by adipocytes in their ability to infiltrate.

METHODS

We investigated the phenotypic conversion of adipocytes during the malignant process of GC cells in vivo and in vitro. We evaluated the expression levels of adiponectin in the omental adipose tissue of gastric cancer patients by western blotting. Following adipocytes/gastric cancer cells coculture, adipocyte markers, adiponectin receptors, and inflammatory cytokine markers were detected by real-time PCR and/or western blotting in the single-cultured and co-cultured adipocytes; cancer-associated fibroblast (CAF) markers were detected by immunofluorescence and western blotting in the single-cultured and co-cultured adipocytes; invasion assays were performed in single cultured and co-cultured MKN45 and OCUM.

RESULTS

In omental adipose tissues that are situated close to the primary tumors, the expression of adiponectin tended to decrease in patients with subserosal or serosal invasion. By co-culturing with GC cells, adipocytes were dedifferentiated and the expression levels of CAF marker FSP1 and inflammatory cytokines, PAI-1 and IL-6, significantly increased (p < 0.05). Furthermore, GC cells co-cultured with adipocytes showed enhanced invasion ability.

CONCLUSION

Our findings suggest that the phenotypic conversion of adipocytes may promote the malignancy of GC in the construction of the cancer microenvironment of PM.

Molecular Mechanisms and Potential Rationale of Immunotherapy in Peritoneal Metastasis of Advanced Gastric Cancer

Peritoneal metastasis (PM) is one of the most frequent metastasis patterns of gastric cancer (GC), and the prognosis of patients with PM is very dismal. According to Paget’s theory, disseminated free cancer cells are seeded and survive in the abdominal cavity, adhere to the peritoneum, invade the subperitoneal tissue, and proliferate through angiogenesis. In these sequential processes, several key molecules are involved. From a therapeutic point of view, immunotherapy with chemotherapy combination has become the standard of care for advanced GC. Several clinical trials of newer immunotherapy agents are ongoing. Understanding of the molecular process of PM and the potential rationale of immunotherapy for PM treatment is necessary. Beyond understanding of the molecular aspect of PM, many studies have been conducted on the modality of treatment of PM. Notably, intraperitoneal approaches, including chemotherapy or immunotherapy, have been conducted, because systemic treatment of PM has limitations. In this study, we reviewed the molecular mechanisms and immunologic aspects of PM, and intraperitoneal approaches under investigation for treating PM.

Impact of Selected Serum Factors on Metastatic Potential of Gastric Cancer Cells

(1) Background: stromal-derived factor-1 (SDF-1/CXCL12), hepatocyte and vascular-endothelial growth factors (HGF and VEGF) have been shown to facilitate cell motility, proliferation and promote local tumor progression and metastatic spread. Recent research shows the important role of these cytokines in gastric cancer (GC) progression. (2) Methods: 21 gastric cancer patients and 19 healthy controls were included in the study. SDF-1, HGF and VEGF levels were evaluated in sera by ELISA. Patients and control sera were used to stimulate CRL-1739 GC cell line, and chemotaxis, adhesion and proliferation potential were assessed. (3) Results: Concentrations of SDF-1, HGF and VEGF were significantly higher in patients than in controls. Chemotaxis and adhesion assays revealed a significant response of GC cells to patients’ serum. Furthermore, significant relationships were seen between chemotactic/adhesion response and tumor stage. Serum from intestinal early GC patients produced significantly stronger chemotactic response when compared to patients with metastatic spread. In turn, serum from patients with distal metastases significantly increased the adhesion of GC cells when compared to sera from the patients with no distal metastases. We also observed that HGF strongly stimulated the proliferation of CRL-1739 cells. (4) Conclusions: We observed that the sera from GC patients, but also SDF-1, HGF and VEGF used alone, have a strong pro-metastatic effect on CRL-1739 cells. We also demonstrated that the concentration of these cytokines is specifically elevated in the sera of patients in an early stage of malignancy. Our results indicate that SDF-1, HGF and VEGF are very important molecules involved in gastric cancer progression.

Oncolytic Virotherapy in Peritoneal Metastasis Gastric Cancer: The Challenges and Achievements

Gastric cancer (GC) is the fourth most common cancer and the second leading cause of cancer death globally. Although the mortality rate in some parts of the world, such as East Asia, is still high, new treatments and lifestyle changes have effectively reduced deaths from this type of cancer. One of the main challenges of this type of cancer is its late diagnosis and poor prognosis. GC patients are usually diagnosed in the advanced stages of the disease, which is often associated with peritoneal metastasis (PM) and significantly reduces survival. This type of metastasis in patients with GC poses a serious challenge due to limitations in common therapies such as surgery and tumor resection, as well as failure to respond to systemic chemotherapy. To solve this problem, researchers have used virotherapy such as reovirus-based anticancer therapy in patients with GC along with PM who are resistant to current chemotherapies because this therapeutic approach is able to overcome immune suppression by activating dendritic cells (DCs) and eventually lead to the intrinsic activity of antitumor effector T cells. This review summarizes the immunopathogenesis of peritoneal metastasis of gastric cancer (PMGC) and the details for using virotherapy as an effective anticancer treatment approach, as well as its challenges and opportunities.

Quantifying the cell morphology and predicting biological behavior of signet ring cell carcinoma using deep learning

Signet ring cell carcinoma (SRCC) is a malignant tumor of the digestive system. This tumor has long been considered to be poorly differentiated and highly invasive because it has a higher rate of metastasis than well-differentiated adenocarcinoma. But some studies in recent years have shown that the prognosis of some SRCC is more favorable than other poorly differentiated adenocarcinomas, which suggests that SRCC has different degrees of biological behavior. Therefore, we need to find a histological stratification that can predict the biological behavior of SRCC. Some studies indicate that the morphological status of cells can be linked to the invasiveness potential of cells, however, the traditional histopathological examination can not objectively define and evaluate them. Recent improvements in biomedical image analysis using deep learning (DL) based neural networks could be exploited to identify and analyze SRCC. In this study, we used DL to identify each cancer cell of SRCC in whole slide images (WSIs) and quantify their morphological characteristics and atypia. Our results show that the biological behavior of SRCC can be predicted by quantifying the morphology of cancer cells by DL. This technique could be used to predict the biological behavior and may change the stratified treatment of SRCC.

MiR-29b may suppresses peritoneal metastases through inhibition of the mesothelial-mesenchymal transition (MMT) of human peritoneal mesothelial cells

Peritoneal dissemination is a major metastatic pathway for gastrointestinal and ovarian malignancies. The miR-29b family is downregulated in peritoneal fluids in patients with peritoneal metastases (PM). We examined the effect of miR-29b on mesothelial cells (MC) which play critical a role in the development of PM through mesothelial-mesenchymal transition (MMT). Human peritoneal mesothelial cells (HPMCs) were isolated from surgically resected omental tissue and MMT induced by stimulation with 10 ng/ml TGF-β1. MiR-29b mimics and negative control miR were transfected by lipofection using RNAiMAX and the effects on the MMT evaluated in vitro. HPMC produced substantial amounts of miR-29b which was markedly inhibited by TGF-β1. TGF-β1 stimulation of HPMC induced morphological changes with decreased expression of E-cadherin and calretinin, and increased expression of vimentin and fibronectin. TGF-β1 also enhanced proliferation and migration of HPMC as well as adhesion of tumor cells in a fibronectin dependent manner. However, all events were strongly abrogated by simultaneous transfection of miR-29b. MiR-29b inhibits TGF-β1 induced MMT and replacement of miR-29b in the peritoneal cavity might be effective to prevent development of PM partly through the effects on MC.

The prognostic impact of macroscopic serosal change on resectable advanced gastric cancer

BACKGROUND

Advanced gastric cancer sometimes causes macroscopic serosal change (MSC) due to direct invasion or inflammation. However, the prognostic significance of MSC remains unclear.

METHODS

A total of 1410 patients who had been diagnosed with deeper-than-pathological-T2 gastric cancer and undergone R0 gastrectomy with lymph node dissection at the National Cancer Center Hospital during January 2000 and December 2012 were restrospectively reviewed.

RESULTS

MSC was not found in 108 of the 506 patients with pathological T4a (21.3%), whereas it was detected in 250 of the 904 patients with pathological T2-T3 (27.7%). The sensitivity, specificity and accuracy for diagnosing pathological serosa exposed (SE) by MSC were 78.7, 72.3 and 74.6%, respectively. The MSC-positive cases had a worse 5-year overall survival (OS) than the MSC-negative cases in pT3 (72.9% vs. 84.3%, p = 0.001), pT4a (56.2% vs. 73.4%, p = 0.001), pStageIIB (76.0% vs. 88.4%, p = 0.005), pStageIIIA (63.4% vs. 75.6%, p = 0.019), pStageIIIB (53.6% vs. 69.2%, p = 0.029) and pStage IIIC (27.6% vs. 50.0%, p = 0.062). A multivariate analysis showed that MSC was a significant independent predictor for the OS (hazard ratio [HR]: 1.587, 95%CI 1.209-2.083, p = 0.001) along with the tumor depth (HR: 7.742, 95%CI: 2.935-20.421, p < 0.001), nodal status (HR:5.783, 95% CI 3.985-8.391, p < 0.001) and age (HR:2.382, 95%CI: 1.918-2.957, p < 0.001). Peritoneal recurrence rates were higher in the MSC-positive cases than in the MSC-negative cases at each pT stage.

CONCLUSIONS

In this study, the MSC was one of the independent prognostic factors in patients with resectable locally advanced gastric cancer.

Slug and CD133 expression are associated with peritoneal carcinomatosis and survival in gastric cancer

Background

Slug is an activating transcription factor involved in epithelial-mesenchymal transition, and CD133 is a cancer stem cell marker found in various cancers, including gastric cancer (GC). We investigated the relationship between Slug and CD133 and the occurrence of peritoneal carcinomatosis and survival in patients with GC.

Methods

This retrospective study included 196 patients with stage 2 or 3 GC who underwent curative surgery with D2 lymph node dissection and adjuvant chemotherapy between 2001 and 2009. We analyzed the expression of Slug, CD133, ABCG2, E-cadherin, vimentin, NEDD9, and SMAD4 in surgical tissue specimens using immunohistochemical analysis to determine their prognostic value.

Results

Among the 196 patients, expression of Slug was elevated in 157 tumors (81%) while the expression of CD133 was high in 153 tumors (81%). The expression of Slug and CD133 in combination significantly predicted peritoneal relapse (P=0.002). High Slug and high CD133 expression were significantly associated with poor peritoneal relapse-free survival [hazard ratio (HR), 7.239; P=0.007] and overall survival (HR, 1.682; P=0.027) in multivariate Cox analysis.

Conclusions

Our study shows that a high Slug and high CD133 expression status is predictive of peritoneal recurrence in high-risk resected GC patients. They are also a poor prognostic factor for peritoneal relapse-free survival and overall survival.

SHP2 as a Potential Therapeutic Target in Diffuse-Type Gastric Carcinoma Addicted to Receptor Tyrosine Kinase Signaling

Simple Summary

Diffuse-type gastric carcinoma (DGC) is characterized by rapid infiltrative growth associated with massive stroma and frequent peritoneal dissemination, which leads to poor patient outcomes. In this study, we found that the oncogenic tyrosine phosphatase SHP2 is tyrosine-phosphorylated downstream of the amplified receptor tyrosine kinases (RTKs) Met and fibroblast growth factor receptor 2 (FGFR2) in DGC cell lines. SHP2 knockdown or pharmacological inhibition selectively suppressed the growth of DGC addicted to amplified Met and FGFR2. Moreover, targeting SHP2 abrogated malignant phenotypes, including peritoneal dissemination, of Met-addicted DGC and could overcome acquired resistance to Met inhibitors. Our findings suggest that SHP2 is a potential target for the treatment of DGC addicted to amplified RTK signaling.

Abstract

Diffuse-type gastric carcinoma (DGC) exhibits aggressive progression associated with rapid infiltrative growth, massive fibrosis, and peritoneal dissemination. Gene amplification of Met and fibroblast growth factor receptor 2 (FGFR2) receptor tyrosine kinases (RTKs) has been observed in DGC. However, the signaling pathways that promote DGC progression downstream of these RTKs remain to be fully elucidated. We previously identified an oncogenic tyrosine phosphatase, SHP2, using phospho-proteomic analysis of DGC cells with Met gene amplification. In this study, we characterized SHP2 in the progression of DGC and assessed the therapeutic potential of targeting SHP2. Although SHP2 was expressed in all gastric carcinoma cell lines examined, its tyrosine phosphorylation preferentially occurred in several DGC cell lines with Met or FGFR2 gene amplification. Met or FGFR inhibitor treatment or knockdown markedly reduced SHP2 tyrosine phosphorylation. Knockdown or pharmacological inhibition of SHP2 selectively suppressed the growth of DGC cells addicted to Met or FGFR2, even when they acquired resistance to Met inhibitors. Moreover, SHP2 knockdown or pharmacological inhibition blocked the migration and invasion of Met-addicted DGC cells in vitro and their peritoneal dissemination in a mouse xenograft model. These results indicate that SHP2 is a critical regulator of the malignant progression of RTK-addicted DGC and may be a therapeutic target.

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.

Clinical importance of carcinoembryonic antigen messenger RNA level in peritoneal lavage fluids measured by transcription-reverse transcription concerted reaction for advanced gastric cancer in laparoscopic surgery

BACKGROUND

Transcription-reverse transcription concerted reaction (TRC) is recognized as a useful method for detecting free cancer cells in the peritoneal cavity and predicting peritoneal recurrence in patients with gastric cancer. Nonetheless, the clinical significance of TRC in laparoscopic surgery remains unclear. This study aimed to evaluate the clinical importance of carcinoembryonic antigen (CEA) messenger RNA (mRNA) level in peritoneal lavage fluids measured by TRC in laparoscopic surgery for locally advanced gastric cancer.

METHODS

We enrolled patients with locally advanced gastric cancer who underwent laparoscopic gastrectomy. Peritoneal lavage fluids were collected prior to gastrectomy, and the TRC method was employed to quantify CEA mRNA in peritoneal washes. Overall survival (OS), recurrence-free survival (RFS), and peritoneal recurrence-free survival (PRFS) were analyzed using the Kaplan-Meier method and compared using the log-rank test. Adjusted Cox proportional hazards regression models were used to calculate the hazard ratios (HRs) for CEA mRNA positivity.

RESULTS

A total of 100 patients were analyzed in this study. Overall, 22 patients (22%) exhibited CEA mRNA positivity in peritoneal lavage fluids, as measured by TRC. No significant association between CEA mRNA levels and clinicopathological characteristics was observed. Patients who were CEA mRNA-positive in peritoneal lavage fluids had significantly worse OS, RFS, and PRFS than those who were CEA mRNA-negative (p = 0.0059, p < 0.0001, and p = 0.0022, respectively). In the univariate Cox model, the HR for all-cause mortality in CEA mRNA-positive versus CEA mRNA-negative patients was 3.60 (95% CI, 1.33-9.55; p = 0.0129). Multivariate analysis revealed that CEA mRNA positivity was a significant independent factor for recurrence.

CONCLUSIONS

TRC enables the detection of free cancer cells in the peritoneal cavity and CEA mRNA levels can help predict the prognosis, even in laparoscopic gastrectomy.

LIMK1 promotes peritoneal metastasis of gastric cancer and is a therapeutic target

Peritoneal metastasis is a common form of metastasis among advanced gastric cancer patients. In this study, we reported the identification of LIM domain kinase 1 (LIMK1) as a promoter of gastric cancer peritoneal metastasis, and its potential to be a therapeutic target of dabrafenib (DAB). Using transcriptomic sequencing of paired gastric cancer peritoneal metastasis, primary tumors, and normal gastric tissues, we first unveiled that LIMK1 is selectively up-regulated in metastatic tumors. Increased LIMK1 in gastric cancer peritoneal metastasis was validated by immunohistochemistry analysis of an independent patient cohort. In vitro functional studies demonstrated that LIMK1 knockout or knockdown significantly inhibited cell migration and invasion of gastric cancer cells. LIMK1 knockout also abrogated peritoneal and liver metastases of gastric cancer cells in nude mice in vivo. Dabrafenib, a small molecule targeting LIMK1, was found to decrease cell migration and invasion of gastric cancer cells in vitro and abolish peritoneal and liver metastasis formation in vivo. Mechanistically, either LIMK1 knockout or Dabrafenib inhibited LIMK1 expression and phosphorylation of its downstream target cofilin. Taken together, our results demonstrated that LIMK1 functions as a metastasis promoter in gastric cancer by inhibiting LIMK1-p-cofilin and that Dabrafenib has the potential to serve as a novel treatment for gastric cancer peritoneal metastasis.

Hepatic metastasis of gastric cancer is associated with enhanced expression of ethanolamine kinase 2 via the p53-Bcl-2 intrinsic apoptosis pathway

BACKGROUND

Gastric cancer (GC) with hepatic metastasis has a poor prognosis. Understanding the molecular mechanisms involved in hepatic metastasis may contribute to the development of sensitive diagnostic biomarkers and novel therapeutic strategies.

METHODS

We performed transcriptome analysis of surgically resected specimens from patients with advanced GC. One of the genes identified as specifically associated with hepatic metastasis was selected for detailed analysis. GC cell lines with knockout of the candidate gene were evaluated in vitro and in vivo. Expression of the candidate gene was analysed in GC tissues from 300 patients.

RESULTS

Ethanolamine kinase 2 (ETNK2) was differentially upregulated in GC patients with hepatic metastasis. ETNK2 expression was elevated in GC cell lines derived from haematogenous metastases. ETNK2 knockout significantly suppressed proliferation, invasion, and migration; increased apoptosis; reduced Bcl-2 protein expression; and increased phosphorylated p53 expression. In mouse xenograft models, ETNK2 knockout virtually abolished hepatic metastasis. Stratification of GC patients based on ETNK2 mRNA level revealed significant associations between high ETNK2 tumour expression and both hepatic recurrence and worse prognosis.

CONCLUSIONS

Upregulation of ETNK2 in GC enhances hepatic metastasis, possibly via dysregulation of p53-Bcl-2-associated apoptosis. ETNK2 expression may serve as a biomarker for predicting hepatic recurrence and a therapeutic target.

PLEKHA5 regulates the survival and peritoneal dissemination of diffuse-type gastric carcinoma cells with Met gene amplification

Met gene amplification has been found in a subset of malignant carcinomas, including diffuse-type gastric carcinoma (DGC), which has a poor prognosis owing to rapid infiltrative invasion and frequent peritoneal dissemination. Met is considered a promising therapeutic target for DGC. However, DGC cells with Met gene amplification eventually acquire resistance to Met inhibitors. Therefore, identification of alternate targets that mediate Met signaling and confer malignant phenotypes is critical. In this study, we conducted a phosphoproteomic analysis of DGC cells possessing Met gene amplification and identified Pleckstrin Homology Domain Containing A5 (PLEKHA5) as a protein that is tyrosine-phosphorylated downstream of Met. Knockdown of PLEKHA5 selectively suppressed the growth of DGC cells with Met gene amplification by inducing apoptosis, even though they had acquired resistance to Met inhibitors. Moreover, PLEKHA5 silencing abrogated the malignant phenotypes of Met-addicted DGC cells, including peritoneal dissemination in vivo. Mechanistically, PLEKHA5 knockdown dysregulates glycolytic metabolism, leading to activation of the JNK pathway that promotes apoptosis. These results indicate that PLEKHA5 is a novel downstream effector of amplified Met and is required for the malignant progression of Met-addicted DGC.

Ovulatory Follicular Fluid Facilitates the Full Transformation Process for the Development of High-Grade Serous Carcinoma

Background: High-grade serous carcinoma (HGSC) is mainly derived from the stepwise accumulation of driver mutations in the fallopian tube epithelium (FTE), and it subsequently metastasizes to the ovary and peritoneum that develops into a clinically evident ovarian carcinoma. The developmental process involves cell proliferation/clonal expansion, cell migration, anoikis resistance, anchorage-independent growth (AIG), peritoneum attachment, and cell invasion. Previously, we discovered FTE could be transformed by follicular fluid (FF) released from ovulation, the most crucial risk factor of ovarian cancer, and IGF axis proteins in FF confers stemness activation and clonal expansion via IGF-1R/AKT pathway. However, whether other phenotypes in advanced cancer development are involved is unknown. Methods: A panel of FTE and ovarian HGSC cell lines with different severity of transformation were treated with FF with or without IGF-1R and AKT inhibitors and analyzed for the transformation phenotypes in vitro, ex vivo, and in vivo. Results: FF largely promotes (by order of magnitude) cell migration, AIG, cell invasion, peritoneum attachment, anoikis resistance, and cell proliferation. Most of these activities worked in the full panel of cell lines. The AIG activity largely depends on IGF-1R/AKT phosphorylation, and the proliferation activity depends on an AKT phosphorylation not mediated by IGF-1R. In contrast, both AKT- and non-AKT-mediated signals are responsible for the other transformation activities. Conclusions: Our data demonstrate an extensive transformation activity of FF in the full journey of carcinogenesis, and endorsed ovulation-inhibition for the prevention and AKT-inhibition for the treatment of ovarian HGSC.

Clinical Significance of CLDN18.2 Expression in Metastatic Diffuse-Type Gastric Cancer

Purpose

Isoform 2 of tight junction protein claudin-18 (CLDN18.2) is a potential target for gastric cancer treatment. A treatment targeting CLDN18.2 has shown promising results in gastric cancer. We investigated the clinical significance of CLDN18.2 and other cell-adherens junction molecules (Rho GTPase-activating protein [RhoGAP] and E-cadherin) in metastatic diffuse-type gastric cancer (mDGC).

Materials and Methods

We evaluated CLDN18.2, RhoGAP, and E-cadherin expression using two-plex immunofluorescence and quantitative data analysis of H-scores of 77 consecutive mDGC patients who received first-line platinum-based chemotherapy between March 2015 and February 2017.

Results

CLDN18.2 and E-cadherin expression was significantly lower in patients with peritoneal metastasis (PM) than those without PM at the time of diagnosis (P=0.010 and 0.013, respectively), whereas it was significantly higher in patients who never developed PM from diagnosis to death than in those who did (P=0.001 and 0.003, respectively). Meanwhile, CLDN18.2 and E-cadherin expression levels were significantly higher in patients with bone metastasis than in those without bone metastasis (P=0.010 and 0.001, respectively). Moreover, we identified a positive correlation between the expression of CLDN18.2 and E-cadherin (P<0.001), RhoGAP and CLDN18.2 (P=0.004), and RhoGAP and E-cadherin (P=0.001). Conversely, CLDN18.2, RhoGAP, and E-cadherin expression was not associated with chemotherapy response and survival.

Conclusions

CLDN18.2 expression was reduced in patients with PM but significantly intact in those with bone metastasis. Furthermore, CLDN18.2 expression was positively correlated with other adherens junction molecules, which is clinically associated with mDGC and PM pathogenesis.

A Case of Peritoneal Dissemination and Splenic Metastasis after Gastric Cancer Surgery That Could Be Controlled with Multidisciplinary Treatment

Splenic metastasis is known to occur at the terminal stage of cancer. While peritoneal dissemination is the most frequent recurrence of gastric cancer, metastasis to the spleen from gastric cancer is very rare. Splenectomy is currently the most effective probable treatment for solitary splenic metastasis of gastric cancer; it provides a good patient prognosis. However, careful consideration of surgical indications is required, as splenic metastasis is typically accompanied by multi-organ metastasis and dissemination. One of the main cancer treatment methods is the “wait-and-see” approach using chemotherapy. In general, patients with gastric cancer are treated with systemic chemotherapy for distant metastases including peritoneal dissemination. Radiotherapy is not commonly used to prolong life in patients with gastric cancer as gastric cancer is predominantly adenocarcinoma. However, a recent report indicated that chemo-radiotherapy was performed successfully for unresectable gastric cancer, including peritoneal dissemination. Here, we present the case of a 67-year-old patient who was observed to have peritoneal dissemination and splenic metastasis after gastric cancer surgery. Once the peritoneal dissemination was localized, surgical excision and chemo-radiotherapy were performed. We treated the splenic metastasis with the “wait-and-see” strategy with chemotherapy. A complete response on imaging in accordance with the Response Evaluation Criteria in Solid Tumors was achieved using multidisciplinary treatment. Our strategy of intensive multidisciplinary therapy could be a treatment option for cases with peritoneal dissemination or splenic metastasis of gastric cancer.

The role of bursectomy in the surgical management of gastric cancer: a meta-analysis and systematic review

In order to delineate the exact role of bursectomy (BS) in gastric cancer surgery, we designed and conducted the present meta-analysis. This meta-analysis adhered to the PRISMA guidelines and the Cochrane Handbook for Systematic Reviews of Interventions. A systematic literature review of the electronic databases (Medline, Scopus, Web of Science) was performed. Trial sequential analysis (TSA) was introduced for the validation of the pooled analyses. The level of evidence was attributed based on the GRADE approach. Overall, nine studies and 3599 patients were included in our meta-analysis. BS did not lead to an increase in the overall morbidity rate (OR 1.17, 95% CI 0.97-1.42, p = 0.09). Equivalence was, also, identified in all specific postoperative complications. Similarly, mortality rates were comparable (p = 0.69). Moreover, BS was related to a significantly higher operative time (p < 0.001) and perioperative blood loss (p = 0.002). Finally, resection of the omental bursa was not associated with improved R0 excision rates (p = 0.92), lymph node harvest (p = 0.1) or survival outcomes (OS p = 0.15 and DFS p = 0.97). BS displayed a suboptimal perioperative performance without any significant oncological efficacy. Due to certain limitations and the low level of evidence, further high-quality RCTs are required.

Rare Abdominal Wall Metastasis following Curative Resection of Gastric Cancer: What Can Be Learned from the Use of Percutaneous Catheters?

In cancer care, tissue seeding after curative resections is a known potential complication, despite precautions taken during surgical treatment. We present an uncommon case of an abdominal wall metastasis along the tract of a surgical drain following gastrectomy for gastric adenocarcinoma. To our knowledge, this is the first case of such an occurrence in the setting of a negative staging peritoneal lavage. Aside from the rarity of such a recurrence, this instance highlights an opportunity to reevaluate best practices with regard to the extent of coverage of postoperative salvage radiotherapy. The oncologic patient provides many challenges and may require multiple catheters for drainage and at times infusion of nutrition or therapeutic agents. These foreign bodies should be scrutinized both clinically and radiographically, as they may create vulnerabilities in keeping malignant diseases contained and controlled. We provide a review of the literature with reasonable treatment options for the benefit of future patients.

Immunological Aspects of the Tumor Microenvironment and Epithelial-Mesenchymal Transition in Gastric Carcinogenesis

Infection with Helicobacter pylori, a Gram-negative, microaerophilic pathogen often results in gastric cancer in a subset of affected individuals. This explains why H. pylori is the only bacterium classified as a class I carcinogen by the World Health Organization. Several studies have pinpointed mechanisms by which H. pylori alters signaling pathways in the host cell to cause diseases. In this article, the authors have reviewed 234 studies conducted over a span of 18 years (2002-2020). The studies investigated the various mechanisms associated with gastric cancer induction. For the past 1.5 years, researchers have discovered new mechanisms contributing to gastric cancer linked to H. pylori etiology. Alongside alteration of the host signaling pathways using oncogenic CagA pathways, H. pylori induce DNA damage in the host and alter the methylation of DNA as a means of perturbing downstream signaling. Also, with H. pylori, several pathways in the host cell are activated, resulting in epithelial-to-mesenchymal transition (EMT), together with the induction of cell proliferation and survival. Studies have shown that H. pylori enhances gastric carcinogenesis via a multifactorial approach. What is intriguing is that most of the targeted mechanisms and pathways appear common with various forms of cancer.

Free cancer cells in gastric cancer - methods of detection, clinical and prognostic importance (meta-analysis)

Gastric cancer (GC) is one of the most common malignant cancers worldwide. Intraperitoneal dissemination is the typical mechanism of the formation of metastases in GC. The diagnosis of the presence of intraperitoneal free cancer cells (IFCCs) is treated equally to the M (metastasis) category according to the 8^th edition of the TNM classification by the American Joint Committee on Cancer. IFCCs are cells which have detached from the primary tumour through exfoliation into the peritoneal cavity. The source of IFCCs may be iatrogenic due to improper surgical technique during resection of the tumour and may lead to intraperitoneal dissemination. Cytological examination of peritoneal lavage is considered as a gold standard in the confirmation of the presence of IFCCs; however, its sensitivity is very low. In order to increase the sensitivity and reliability of the examination, molecular biology techniques should be applied. In the case of detection of the presence of IFCCs in patients with GC, the patient should be qualified for chemotherapy, or possibly the use of hyperthermic intraperitoneal chemotherapy should be considered.

Transcriptomic and Genomic Testing to Guide Individualized Treatment in Chemoresistant Gastric Cancer Case

Gastric cancer is globally the fifth leading cause of cancer death. We present a case report describing the unique genomic characteristics of an Epstein–Barr virus-negative gastric cancer with esophageal invasion and regional lymph node metastasis. Genomic tests were performed first with the stomach biopsy using platforms FoundationOne, OncoDNA, and Oncopanel at Dana Farber Institute. Following neoadjuvant chemotherapy, residual tumor was resected and the stomach and esophageal residual tumor samples were compared with the initial biopsy by whole exome sequencing and molecular pathway analysis platform Oncobox. Copy number variation profiling perfectly matched the whole exome sequencing results. A moderate agreement was seen between the diagnostic platforms in finding mutations in the initial biopsy. Final data indicate somatic activating mutation Q546K in PIK3CA gene, somatic frameshifts in PIH1D1 and FBXW7 genes, stop-gain in TP53BP1, and a few somatic mutations of unknown significance. RNA sequencing analysis revealed upregulated expressions of MMP7, MMP9, BIRC5, and PD-L1 genes and strongly differential regulation of several molecular pathways linked with the mutations identified. According to test results, the patient received immunotherapy with anti-PD1 therapy and is now free of disease for 2 years. Our data suggest that matched tumor and normal tissue analyses have a considerable advantage over tumor biopsy-only genomic tests in stomach cancer.

Rational design of small molecule RHOA inhibitors for gastric cancer

Previously, we identified Ras homologous A (RHOA) as a major signaling hub in gastric cancer (GC), the third most common cause of cancer death in the world, prompting us to rationally design an efficacious inhibitor of this oncogenic GTPase. Here, based on that previous work, we extend those computational analyses to further pharmacologically optimize anti-RHOA hydrazide derivatives for greater anti-GC potency. Two of these, JK-136 and JK-139, potently inhibited cell viability and migration/invasion of GC cell lines, and mouse xenografts, diversely expressing RHOA. Moreover, JK-136's binding affinity for RHOA was >140-fold greater than Rhosin, a nonclinical RHOA inhibitor. Network analysis of JK-136/-139 vs. Rhosin treatments indicated downregulation of the sphingosine-1-phosphate, as an emerging cancer metabolic pathway in cell migration and motility. We assert that identifying and targeting oncogenic signaling hubs, such as RHOA, represents an emerging strategy for the design, characterization, and translation of new antineoplastics, against gastric and other cancers.

Microscopic distance from tumor invasion front to serosa might be a useful predictive factor for peritoneal recurrence after curative resection of T3-gastric cancer

Background

Peritoneal recurrence is one of the most frequent recurrent diseases in gastric cancer. Although the exposure of cancer cells to the serosal surface is considered a common risk factor for peritoneal recurrence, there are some cases of peritoneal recurrence without infiltration to the serosal surface even after curative surgery. This study sought to clarify the risk factors of peritoneal recurrence in the absence of invasion to the serosal surface.

Materials and methods

Ninety-six patients with gastric cancer who underwent curative surgery were enrolled. In all 96 cases, the depth of tumor invasion was subserosal (T3). The microscopic distance from the tumor invasion front to the serosa (DIFS) was measured using tissue slides by H&E staining and pan-cytokeratin staining. E-cadherin expression was evaluated by immunohistochemical staining.

Results

Among the 96 patients, 16 developed peritoneal recurrence after curative surgery. The DIFS of the tumors with peritoneal recurrence (156±220 μm) was significantly shorter (p = 0.011) than that without peritoneal recurrence (360±478 μm). Peritoneal recurrence was significantly correlated with DIFS ≤234 μm (p = 0.023), but not with E-cadherin expression. The prognosis of DIFS ≤234 μm was significantly poorer than that of DIFS >234 μm (log rank, p = 0.007). A multivariate analysis of the patients' five-year overall survival revealed that DIFS ≤234 μm and lymph node metastasis were significantly correlated with survival (p = 0.005, p = 0.032, respectively).

Conclusion

The measurement of the DIFS might be useful for the prediction of peritoneal recurrence in T3-gastric cancer patients after curative surgery.

Issues on peritoneal metastasis of gastric cancer: an update

Background

Peritoneal metastasis (PM) is one of the most common forms of metastasis with a very poor prognosis in patients with gastric cancer (GC). The mechanisms, diagnosis, and management of PM remain controversial.

Main body

Stephen Paget’s “seed-and-soil” hypothesis gives us an illustration of the mechanisms of PM. Recently, hematogenous metastasis and exosomes from GC are identified as novel mechanisms for PM. Diagnostic accuracy of conventional imaging modalities for PM is not satisfactory, but texture analysis may be a useful adjunct for the prediction of PM. Biological markers in peritoneal washings are helpful in identifying patients at high risk of PM, but many limitations remain to be overcome. Response of PM from systemic chemotherapy alone is very limited. However, conversion therapy is confirmed to be safe and able to prolong the survival of GC patients with PM. As an important part of conversion therapy, intraperitoneal chemotherapy with taxanes has become an ideal approach with several advantages. Additionally, gastrectomy should be considered in patients who would tolerate surgery if a remarkable response to chemotherapy was observed.

Conclusion

Texture analysis is a reliable adjunct for the prediction of PM, and conversion therapy provides a new choice for GC patients with PM. The underlying mechanisms and new biological markers for GC patients with PM should be the direction of future studies. Furthermore, significant aspects of conversion therapy, such as timing and method of the operation, and the indications remain to be clarified.

A self-enforcing HOXA11/Stat3 feedback loop promotes stemness properties and peritoneal metastasis in gastric cancer cells

Rationale: Peritoneal metastasis is one of the most common and life-threatening metastases in gastric cancer patients. The disseminated gastric cancer cells forming peritoneal metastasis exhibit a variety of characteristics that contrast with those of adjacent epithelial cell of gastric mucosa and even primary gastric cancer cells. We hypothesized that the gene expression profiles of peritoneal foci could reveal the identities of genes that might function as metastatic activator.

Methods: In this study, we show, using in vitro, in vivo, in silico and gastric cancer tissues studies in humans and mice, that Homoebox A11 (HOXA11) potently promote peritoneal metastasis of gastric cancer cells.

Results: Its mechanism of action involves alternation of cancer stemness and subsequently enhancement of the adhesion, migration and invasion and anti-apoptosis. This is achieved, mainly, through formation of a positive feedback loop between HOXA11 and Stat3, which is involved in the stimulation of Stat3 signaling pathway.

Conclusions: These observations uncover a novel peritoneal metastatic activator and demonstrate the association between HOXA11, Stat3 and cancer stemness of gastric cancer cells, thereby revealing a previously undescribed mechanism of peritoneal metastasis.

Development and Biological Analysis of a Novel Orthotopic Peritoneal Dissemination Mouse Model Generated Using a Pancreatic Ductal Adenocarcinoma Cell Line

OBJECTIVES

Peritoneal dissemination (PD) is an important cause of morbidity and mortality among patients with pancreatic ductal adenocarcinoma (PDAC). We sought to develop and characterized a novel PD mouse model by using a previously established PDAC cell line TCC-Pan2.

METHODS

TCC-Pan2 cell line was characterized for growth rate, tumor markers, histology, and somatic mutations. TCC-Pan2 cells were implanted orthotopically to produce PD. TCC-Pan2 cells from these metastatic foci were expanded in vitro and then implanted orthotopically in mice. This PD model was used for comparing the antitumor effect of paclitaxel and NK105.

RESULTS

Orthotopically implanted TCC-Pan2 cells caused tumor formation and PD with high frequency in mice. A potent metastatic subline-Pan2M-was obtained. NK105 exerted a stronger antitumor effect than paclitaxel against Pan2M cells harboring a luciferase gene (Pan2MmLuc). Notably, the survival rate on day 80 in the Pan2MmLuc mouse model was 100% for the NK105 group and 0% for the paclitaxel group.

CONCLUSION

TCC-Pan2 cell line and Pan2MmLuc PD model can serve as useful tools for monitoring the responses to antineoplastic agents and for studying PDAC biology.