Differential gene expression in growth factors, epithelial mesenchymal transition and chemotaxis in the diffuse type compared with the intestinal type of gastric cancer

Establishment and verification of prediction model of occult peritoneal metastasis in advanced gastric cancer

BACKGROUND

To investigate the risk factors associated with the development of occult peritoneal metastasis in advanced gastric cancer, and establish and externally validate a nomogram for predicting the occurrence of occult peritoneal metastasis in patients with advanced gastric cancer.

METHODS

A total of 111 patients with advanced gastric cancer who underwent laparoscopic exploration or peritoneal lavage cytology examination at the Affiliated Drum Tower Hospital of Nanjing University Medical School from August 2014 to December 2021 were retrospectively analyzed. The patients diagnosed between 2019 and 2021 were assigned to the training set (n = 64), while those diagnosed between 2014 and 2016 constituted the external validation set (n = 47). In the training set, patients were classified into two groups based on preoperative imaging and postoperative pathological data: the occult peritoneal metastasis group (OPMG) and the peritoneal metastasis negative group (PMNG). In the validation set, patients were classified into the occult peritoneal metastasis group (CY1P0, OPMG) and the peritoneal metastasis negative group (CY0P0, PMNG) based on peritoneal lavage cytology results. A nomogram was constructed using univariate and multivariate analyses. The performance of the nomogram was evaluated using Harrell's C-index, the area under the receiver operating characteristic curve (AUC), decision curve analysis (DCA), and calibration plots.

RESULTS

This study analyzed 22 potential variables of OPM in 111 gastric cancer patients who underwent laparoscopic exploration or peritoneal lavage cytology examination. Logistic regression analysis results showed that Lauren classification, CLDN18.2 score and CA125 were independent risk factors for OPM in patients with gastric cancer. We developed a simple and easy-to-use prediction nomogram of occult peritoneal metastasis in advanced gastric cancer. This nomogram had an excellent diagnostic performance. The AUC of the bootstrap model in the training set was 0.771 and in the validation set was 0.711. This model showed a good fitting and calibration and positive net benefits in decision curve analysis.

CONCLUSION

We have developed a prediction nomogram of OPM for gastric cancer. This novel nomogram has the potential to enhance diagnostic accuracy for occult peritoneal metastasis in gastric cancer patients.

Diffuse-type Gastric Cancer

Gastric cancer is the most prevalent malignant tumor in Korea. Histologically, it is often classified into intestinal-type and diffuse-type. Intestinal-type gastric cancer is known to occur mainly from chronic gastritis caused by Helicobacter pylori (H. pylori) through atrophic gastritis and intestinal metaplasia, a precancerous change of the mucosa, whereas diffuse-type gastric cancer is caused by H. pylori infection, wherein active inflammation of the gastric mucosa occurs without precancerous changes in the mucosa. Compared with intestinal-type gastric cancer, it occurs at a young age, there is no difference in male to female ratio, or tends to occur more in women, and is more aggressive than intestinal-type gastric cancer. Intestinal-type gastric cancer is predominant in East Asian populations such as Koreans and Japanese, whereas diffuse-type gastric cancer has more uniform geographic distribution. In the present manuscript, I have reviewed diffuse-type gastric cancer, distinct from intestinal-type gastric cancer.

Differential Expression of Genes Involved in Metabolism and Immune Response in Diffuse and Intestinal Gastric Cancers, a Pilot Ptudy

Gastric cancer (GC) is one of the major causes of cancer-related mortality worldwide. The vast majority of GC cases are adenocarcinomas including intestinal and diffuse GC. The incidence of diffuse GCs, often associated with poor overall survival, has constantly increased in USA and Europe The molecular basis of diffuse GC aggressivity remains unclear. Using mRNA from diffuse and intestinal GC tumor samples of a Western cohort, this study reports the expression level of the immunomodulatory aryl-hydrocarbon receptor (AhR), and genes involved in immune suppression (PD1, PD-L1, PD-L2) and the early steps of tryptophan metabolism (IDO1, IDO2, TDO2). Strongly increased expression of IDO1 (p < 0.001) and PD1 (p < 0.003) was observed in the intestinal sub-type. The highest expression of IDO1 and PDL1 correlated with early clinical stage and absence of lymphatic invasion (×25 p = 0.004, ×3 p = 0.04, respectively). Our results suggest that kynurenine, produced by tryptophan catabolism, and AhR activation play a central role in creating an immunosuppressive environment. Correspondingly, as compared to intestinal GCs, expression levels of IDO1-TDO2 and PD-L1 were less prominent in diffuse GCs which also had less infiltration of immune cells, suggesting an inactive immune response in the advanced diffuse GC. Confirmation of these patterns of gene expression will require a larger cohort of early and advanced stages of diffuse GC samples.

Detection of Persistent Organic Pollutants in Omental Adipose Tissue from Patients with Diffuse-Gastric Cancer: A Pilot Study

Simple Summary

This pilot study reported the observation that great omentum could be analyzed to detect persistent organic pollutants (POPs). Diffuse gastric cancer is an increasing disease that could be associated with pollutants’ exposition. Here, we report a specific POP profile regarding a patient not affected by cancer, nor by diffuse gastric cancer or other abdominal cancers. The widespread presence of a substantial list of POPs (PCDDs/Fs, PCBs, and brominated flame retardants) was found in the omentum from patients with diffuse gastric cancer with minor presence of some organochlorine pesticides.

Abstract

The greater omentum represents a specific adipose tissue resected with gastric surgery for cancer. Diffuse gastric adenocarcinoma (diffuse-GC) is of major relevance among gastric cancers due to its unknown origin, aggressiveness, and metastasis in the peritoneal cavity. We postulated that persistent organic pollutants (POPs) could be detected in the greater omentum. Great omentum from patients with (i) diffuse-GC, or (ii) with other peritoneal metastatic cancer, and (iii) control group without cancer disease were analyzed for the distribution of a large panel of 96 POPs. POPs include polychlorinated dioxins/furans (PCDD/Fs), polychlorobiphenyls (PCBs), polybrominated diphenyl ethers (PBDE), polybrominated biphenyls (PBB), hexabromocyclododecanes, organochlorine pesticides, and polycyclic aromatic hydrocarbons (PAHs). The widespread presence of a substantial list of POPs (PCDDs/Fs, PCBs, and brominated flame retardants) was found in the omentum from patients with aggressive diffuse-GC, with minor presence of some organochlorine pesticides and PAHs at the low analyzed levels. Some chemicals appeared in larger concentrations in diffuse-GC or other cancer groups, including some PCDDs, PCB105, 123, 138, PBDE209, and PBB153. Overall, the present pilot study provides novel information regarding POPs levels in the omental fat, which is an understudied fat depot in terms of POPs load, and diffuse-GC association.

Serine/threonine-protein kinase 24 is an inhibitor of gastric cancer metastasis through suppressing CDH1 gene and enhancing stemness

Gastric cancer patients often present with distant metastasis and advanced stages. Suppressing serine/threonine-protein kinase 24 (STK24, also known as MST3) is known to promote gastric tumorigenesis. Here, we investigated the effects from STK24 on the metastasis of gastric cancer. We used CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 technology for genetic knockout of STK24 at the genomic DNA level in human MKN45 and mouse M12 gastric cancer cells. To assess the consequences of STK24 knockdown, western blot, cell migration, and wound healing assays were conducted in vitro. An in vivo mouse model of liver metastasis was established and tested, and bioinformatics analyses were performed. The knockdown of the STK24 gene enhanced cell migration and increased liver metastasis in the mouse model of gastric cancer. STK24-silenced tumors suppressed CD4+ T cells and enhanced the expansion of CD11b+Ly6C+ myeloid-derived suppressor cells (MDSCs) and F4/80+ macrophages in the spleen of the mice. In MKN45 cells, STK24 silencing resulted in downregulation of E-cadherin (gene CDH1, Cadherin-1, or epithelial cadherin). In 38 paired specimens of gastric adenocarcinomas and normal tissues, we examined STK24 and CDH1 expression levels via western blot; a positive correlation between the expression levels of STK24 and CDH1 was found (R2 = 0.5507, P = 9.72 × 10-8). Furthermore, in Oncomine database and Kaplan-Meier plotter analysis, the loss of CDH1, increase in CCL2, and upregulation of CD44 were correlated with poor prognosis of gastric cancer patients. Our results demonstrate that knockdown of STK24 increases cell migration through suppressing CDH1 and enhancing CD44. In experimental model of metastatic gastric cancer in syngeneic inbred mice, STK24 is important for immune suppression through expansion of CD11b+Ly6C+ MDSCs and F4/80+ macrophages. We confirmed that STK24 is an inhibitor of gastric cancer metastasis.

Histological differentiation impacts the tumor immune microenvironment in gastric carcinoma: Relation to the immune cycle

BACKGROUND

Various histological types of gastric carcinomas (GCs) differ in terms of their pathogenesis and their preexisting background, both of which could impact the tumor immune microenvironment (TIME). However, the current understanding of the immune contexture of GC is far from complete.

AIM

To clarify the tumor-host immune interplay through histopathological features and the tumor immune cycle concept.

METHODS

In total, 50 GC cases were examined (15 cases of diffuse GC, 31 patients with intestinal-type GC and 4 cases of mucinous GC). The immunophenotype of GC was assessed and classified as immune desert (ID), immune excluded (IE) or inflamed (Inf) according to CD8+ cell count and spatial pattern. In addition, CD68+ and CD163+ macrophages and programmed death-ligand 1 (PD-L1) expression were estimated.

RESULTS

We found that GCs with different histological differentiation demonstrated distinct immune contexture. Most intestinal-type GCs had inflamed TIMEs rich in both CD8+ cells and macrophages. In contrast, more aggressive diffuse-type GC more often possessed ID characteristics with few CD8+ lymphocytes but abundant CD68+ macrophages, while mucinous GC had an IE-TIME with a prevalence of CD68+ macrophages and CD8+ lymphocytes in the peritumor stroma. PD-L1 expression prevailed mostly in intestinal-type Inf-GC, with numerous CD163+ cells observed. Therefore, GCs of different histological patterns have specific mechanisms of immune escape. While intestinal-type GC was more often related to PD-L1 expression, diffuse and mucinous GCs possessing more aggressive behavior demonstrated low immunogenicity and a lack of tumor antigen recognition or immune cell recruitment into the tumor clusters.

CONCLUSION

These data help to clarify the links between tumor histogenesis and immunogenicity for a better understanding of GC biology and more tailored patient management.

CXCR4 and CXCR7 Signaling Pathways: A Focus on the Cross-Talk Between Cancer Cells and Tumor Microenvironment

The chemokine receptor 4 (CXCR4) and 7 (CXCR7) are G-protein-coupled receptors (GPCRs) activated through their shared ligand CXCL12 in multiple human cancers. They play a key role in the tumor/tumor microenvironment (TME) promoting tumor progression, targeting cell proliferation and migration, while orchestrating the recruitment of immune and stromal cells within the TME. CXCL12 excludes T cells from TME through a concentration gradient that inhibits immunoactive cells access and promotes tumor vascularization. Thus, dual CXCR4/CXCR7 inhibition will target different cancer components. CXCR4/CXCR7 antagonism should prevent the development of metastases by interfering with tumor cell growth, migration and chemotaxis and favoring the frequency of T cells in TME. Herein, we discuss the current understanding on the role of CXCL12/CXCR4/CXCR7 cross-talk in tumor progression and immune cells recruitment providing support for a combined CXCR4/CXCR7 targeting therapy. In addition, we consider emerging approaches that coordinately target both immune checkpoints and CXCL12/CXCR4/CXCR7 axis.

A global and physical mechanism of gastric cancer formation and progression

Gastric cancer is regarded as a major health issue for human being nowadays. The Helicobacter pylori (H. pylori) infection has been found to accelerate the development of gastritis and gastric cancer. Significant efforts have been made towards the understanding of the biology of gastric cancer on both genetic and epigenetic levels. However the physical mechanism behind the gastric cancer formation is still elusive. In this study, we constructed a model for investigating gastric cancer formation by explored the gastric cancer landscape and the flow flux. We uncovered three stable state attractors on the landscape: normal, gastritis and gastric cancer. The definition of each attractor is based on the biological function and gene expression levels. The global stabilities and the switching processes were quantified through the barrier heights and dominant kinetic paths. To investigate the underlying mechanism of the process from normal through the gastritis to the gastric cancer caused by genetic or epigenetic factors, we simulate the oncogenesis of gastric cancer through changes of several gene regulation strengths and H. pylori infection. The simulated results can illustrate the developmental and metastasis process of gastric cancer. Different H. pylori infection degrees accelerating the process from gastritis to gastric cancer can be quantified. Then we applied global sensitivity analysis, one key gene and four key regulations were found. These results are consist with the experimental results and can be used to design the polygenic anti-cancer agents through multiple key genes or regulations. The landscape approach provides a physical and simple strategy for analyzing gastric cancer in a systematic and quantitative way. It also offers new insight into treatment strategy for gastric cancer by adjusting relevant polygenic genes and regulations.

Anti-fibrotic properties of an adiponectin paralog protein, C1q/TNF-related protein 6 (CTRP6), in diffuse gastric adenocarcinoma

Patients with advanced gastric cancer, especially diffuse-type gastric cancer, which is often accompanied by stromal fibrosis, commonly exhibit a poor prognosis. This study was designed to unravel the potential roles of C1q/TNF-related protein 6 (CTRP6) in the fibrotic cancer microenvironment of diffuse-type gastric adenocarcinoma. A total of 49 diffuse-type gastric cancer samples were evaluated in this study, and 23 of these samples exhibited focal CTRP6 immunoreactivity. CTRP6 immunoreactivity was found to be correlated with favorable survival outcomes, in terms of both overall and relapse-free survival rates, but this trend did not reach significance (P = 0.15). By contrast, CTRP6 immunoreactivity was significantly correlated with relapse-free survival rates in patients with diffuse-type gastric cancer at a distal site (P = 0.028). Notably, most gastric cancer cells at the cancer invasive front were CTRP6 negative, especially in areas of robust fibrosis. Double immunohistochemical staining demonstrated an inverse expression profile for CTRP6 and the activated fibroblast marker alpha smooth muscle actin (α-sma) in stromal and gastric cancer cells at the cancer invasion front. The addition of recombinant CTRP6 protein attenuated the TGF-β-induced α-sma expression in cultured human fibroblasts but did not alter the proliferation rate or Matrigel-invasion activity of the cultured gastric cancer cells. In addition, CTRP6 did not affect the viability of normal human gastric epithelial cells. This study suggests that CTRP6 may have potential application in combating stromal fibrosis in diffuse-type gastric cancers.

CXCL12 Signaling in the Tumor Microenvironment

Tumor microenvironment (TME) is the local environment of tumor, composed of tumor cells and blood vessels, extracellular matrix (ECM), immune cells, and metabolic and signaling molecules. Chemokines and their receptors play a fundamental role in the crosstalk between tumor cells and TME, regulating tumor-related angiogenesis, specific leukocyte infiltration, and activation of the immune response and directly influencing tumor cell growth, invasion, and cancer progression. The chemokine CXCL12 is a homeostatic chemokine that regulates physiological and pathological process such as inflammation, cell proliferation, and specific migration. CXCL12 activates CXCR4 and CXCR7 chemokine receptors, and the entire axis has been shown to be dysregulated in more than 20 different tumors. CXCL12 binding to CXCR4 triggers multiple signal transduction pathways that regulate intracellular calcium flux, chemotaxis, transcription, and cell survival. CXCR7 binds with high-affinity CXCL12 and with lower-affinity CXCL11, which binds also CXCR3. Although CXCR7 acts as a CXCL12 scavenger through ligand internalization and degradation, it transduces the signal mainly through β-arrestin with a pivotal role in endothelial and neural cells. Recent studies demonstrate that TME rich in CXCL12 leads to resistance to immune checkpoint inhibitors (ICI) therapy and that CXCL12 axis inhibitors sensitize resistant tumors to ICI effect. Thus targeting the CXCL12-mediated axis may control tumor and tumor microenvironment exerting an antitumor dual action. Herein CXCL12 physiology, role in cancer biology and in composite TME, prognostic role, and the relative inhibitors are addressed.

Molecular Network Profiling in Intestinal- and Diffuse-Type Gastric Cancer

Epithelial-mesenchymal transition (EMT) plays an important role in the acquisition of cancer stem cell (CSC) feature and drug resistance, which are the main hallmarks of cancer malignancy. Although previous findings have shown that several signaling pathways are activated in cancer progression, the precise mechanism of signaling pathways in EMT and CSCs are not fully understood. In this study, we focused on the intestinal and diffuse-type gastric cancer (GC) and analyzed the gene expression of public RNAseq data to understand the molecular pathway regulation in different subtypes of gastric cancer. Network pathway analysis was performed by Ingenuity Pathway Analysis (IPA). A total of 2815 probe set IDs were significantly different between intestinal- and diffuse-type GC data in cBioPortal Cancer Genomics. Our analysis uncovered 10 genes including male-specific lethal 3 homolog (Drosophila) pseudogene 1 (MSL3P1), CDC28 protein kinase regulatory subunit 1B (CKS1B), DEAD-box helicase 27 (DDX27), golgi to ER traffic protein 4 (GET4), chromosome segregation 1 like (CSE1L), translocase of outer mitochondrial membrane 34 (TOMM34), YTH N6-methyladenosine RNA binding protein 1 (YTHDF1), ribonucleic acid export 1 (RAE1), par-6 family cell polarity regulator beta (PARD6B), and MRG domain binding protein (MRGBP), which have differences in gene expression between intestinal- and diffuse-type GC. A total of 463 direct relationships with three molecules (MYC, NTRK1, UBE2M) were found in the biomarker-filtered network generated by network pathway analysis. The networks and features in intestinal- and diffuse-type GC have been investigated and profiled in bioinformatics. Our results revealed the signaling pathway networks in intestinal- and diffuse-type GC, bringing new light for the elucidation of drug resistance mechanisms in CSCs.

MicroRNA-381-A Key Transcriptional Regulator: Its Biological Function and Clinical Application Prospects in Cancer

MicroRNAs (miRNAs) are small non-coding RNA molecules that function by regulating messenger RNAs. Recent studies have shown that miRNAs play important roles in multiple processes of cancer development. MiR-381 is one of the most important miRNAs in cancer progression. MiR-381 is downregulated in some cancers and upregulated in other cancers, including glioma, epithelial sarcoma, and osteosarcoma. MiR-381 regulates epithelial-mesenchymal transition (EMT), chemotherapeutic resistance, radioresistance, and immune responses. Thus, miR-381 participates in tumor initiation, progression, and metastasis. Moreover, miR-381 functions in various oncogenic pathways, including the Wnt/β-catenin, AKT, and p53 pathways. Clinical studies have shown that miR-381 could be considered a biomarker or a novel prognostic factor. Here, we summarize the present studies on the role of miR-381 in cancer development, including its biogenesis and various affected signaling pathways, and its clinical application prospects. MiR-381 expression is associated with tumor stage and survival time, making miR-381 a novel prognostic factor.

Preoperative Radiotherapy Is Associated With Significant Survival Benefits for Patients With Gastric Signet Ring Cell Carcinoma: A SEER-Based Approach

Objective:

To explore the clinical and pathological features of gastric signet ring cell carcinoma, and evaluate the survival impact of preoperative radiotherapy on these patients.

Methods:

The Surveillance, Epidemiology, and End Results database was used to extract eligible patients from 2004 to 2015. The patients were divided into those with and without preoperative radiotherapy. The categorical variables were described by chi-square tests. The patients’ survival was compared between the 2 groups by Kaplan-Meier method with log-rank tests. Cox proportional hazard model was adopted to identify prognostic factors of cancer-specific survival.

Results:

Totally 4771 patients were recruited, of whom 218(4.6%) patients received preoperative radiotherapy, while 4553(95.4%) patients didn’t receive this treatment. Survival analysis of the entire cohort demonstrated that preoperative radiotherapy improved both cancer-specific survival and overall survival (p < 0.001) of the patients. Cox proportional hazard models identified age >60, tumor size >50 mm, TNM stage II-IV as independent risk factors for poor prognosis (HR > 1, p < 0.05). Notably, preoperative radiotherapy was identified as an independent protective factor for favorable prognosis (HR < 1, p < 0.05). Subgroup survival analysis showed that preoperative radiotherapy exerted significant survival benefits for the stages III and IV patients.

Conclusions:

In this population-based study, preoperative radiotherapy is associated with significant survival benefits for the patients with advanced gastric signet ring cell carcinoma. Hence preoperative radiotherapy is feasible for these patients.

Radiotherapy benefited the survival of patients with intestinal-type gastric adenocarcinoma: a SEER population-based study

BACKGROUND

Currently, the role of adjuvant radiotherapy (RT) in the treatment of patients with intestinal-type gastric adenocarcinoma (IGA) has not been well established. This study aimed to elucidate the survival impact of RT on such patients.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database was utilized to select eligible patients. The recruited patients were dichotomized into those not received RT versus those received RT. The 1:1 propensity score matching (PSM) analysis was conducted to balance the confounding factors between the two comparison groups. The categorical variables were assessed by Chi-square test. Cancer-specific survival (CSS) and overall survival (OS) of the patients were compared by Kaplan-Meier (KM) methods. Cox proportional hazard models were used to identify prognostic factors associated with CSS.

RESULTS

A total of 3572 eligible patients were enrolled for our analysis, of which, 2896(81.1%) patients did not receive RT and 676(18.9%) patients received RT. Before PSM, except race and tumor size, significant differences in patients' baseline characteristics were observed in no RT versus RT group. The KM plots before PSM indicated that RT exerted significant survival benefits for the recruited patients (p < 0.001). After PSM, most confounders were well balanced between the two comparison groups. The KM plots showed significantly superior CSS and OS in the RT group (p < 0.05). Grade IV, stage II-IV, and N3 were identified as independent risk factors, while LN examined > 15 and RT were independent protective factors for favorable prognosis. Subgroup survival analysis revealed that RT brought a significant CSS advantage for the stage IV patients.

CONCLUSION

Based on PSM analysis of the cohort from SEER database, RT showed significant survival benefits for patients with IGA. Our study supports adjuvant RT for this specific cohort.