Significance of tumor heterogeneity of p-Smad2 and c-Met in HER2-positive gastric carcinoma with lymph node metastasis.

BACKGROUND: Tumor heterogeneity has frequently been observed in gastric cancer (GC), but the correlation between patients' clinico-pathologic features and the tumoral heterogeneity of GC-associated molecules is unclear. We investigated the correlation between lymph node metastasis and the intra-tumoral heterogeneity of driver molecules in GC. MATERIALS AND METHODS: We retrospectively analyzed the cases of 504 patients who underwent a gastrectomy at the Department of Gastroenterological Surgery, Osaka Metropolitan University and 389 cases drawn from The Cancer Genome Atlas (TCGA) data. We performed a clustering analysis based on eight cancer-associated molecules including HER2, c-Met, and p-Smad2 using the protein expression revealed by our immunohistochemical study of the patients' and TCGA cases. We determined the correlations between HER2 expression and the other molecules based on the degree of lymph node metastasis. RESULTS: Immunohistochemical staining data showed that a 43 of the 504 patients with GC (8.5%) were HER2-positive. In the HER2-positive cases, the expressions of c-Met and p-Smad2 were increased in accord with the lymph-node metastatic level. The overall survival of the HER2-positive GC patients with both p-Smad2 and c-Met expression was significantly (p = 0.030) poorer than that of the patients with p-Smad2-negative and/or c-Met-negative expression. The results of the TCGA data analysis revealed that 58 of the 389 GC cases (14.9%) were ERBB2-positive. MET expression was more frequent in the N1 metastasis group than the N0 group. In the high lymph-node metastasis (N2 and N3) group, SMAD2 expression was more frequent, as was ERBB2 and MET expression. CONCLUSION: p-Smad2 and c-Met signaling might play important roles in lymph node metastasis in HER2-positive GC.

Asporin Expression on Stromal Cells and/or Cancer Cells Might Be A Useful Prognostic Marker in Patients with Diffuse-Type Gastric Cancer.

BACKGROUND: Asporin (ASPN), a member of the proteoglycan family, has been shown to have a close correlation with cancer progression. It is not known whether ASPN is an oncogenic driver or a tumor suppressor in human gastric cancer. We sought herein to determine the relationship between ASPN expression and clinicopathological features of gastric cancer. PATIENTS AND METHODS: A total of 296 gastric cancer patients (diffuse type, n = 144; intestinal type, n = 152) were enrolled. The ASPN expression level in each case was analyzed by immunohistochemistry. RESULTS: ASPN was mainly found on stromal cells, especially on fibroblasts in tumor stroma, i.e., cancer-associated fibroblasts. The ASPN expression on either cancer cells or stromal cells was significantly high in macroscopic scirrhous-type tumors (p < 0.001) and histologically abundant stroma-type tumors (p < 0.001). Interestingly, a Kaplan-Meier survival curve of the 144 cases of diffuse-type gastric cancer revealed a significantly poorer prognosis in patients with ASPN-positive expression (p = 0.043; log rank) compared to those with ASPN-negative expression, but the prognoses were not significantly different in these subgroups of the 152 cases of intestinal-type gastric cancer. A multivariate analysis with respect to overall survival showed that ASPN expression on stromal cells and/or cancer cells was significantly correlated with overall survival in patients with diffuse-type gastric cancer (p = 0.041). CONCLUSION: In gastric cancer, ASPN was expressed mainly on stromal cells and partially on cancer cells. ASPN expression on stromal cells and/or cancer cells might be a useful prognostic marker in patients with diffuse-type gastric cancer.

[Effect of Upfront Dose Reduction in the First Cycle of Chemotherapy for Unresectable/Recurrent Gastric Cancers in Patients Aged Over 80 Years].

Chemotherapy for elderly patients requires ingenuity in treatment to mitigate its high risk. Therefore, we investigated an upfront dose reduction in the first cycle of chemotherapy for unresectable/recurrent gastric cancers in patients over 80 years old. We examined 6 patients over 80 years old, who underwent S-1 plus L-OHP therapy(SOX)for unresectable/recurrent gastric cancer in our department between January 2020 and January 2021. There were no adverse events over Grade 3 in the upfront dose reduction group(U group), while 1 case(50.0%)in the normal dose group(N group)experienced an adverse event over Grade 3. Moreover, only the U group continued treatment for 4 or more courses, whereas none from the N group did. Partial response(PR)was achieved as a therapeutic effect in 3 patients of the U group. Only 2 cases of the U group advanced to the second-line regimen and both were able to transition to the third-line regimen. However, none were able to even transition to the second-line regimen in the N group. Therefore, it was suggested that by reducing the dose of chemotherapy from the first cycle for elderly patients over 80 years old, the incidence of adverse events can be kept low, which makes it possible to continue long-term chemotherapy.

Serine threonine kinase 11/liver kinase B1 mutation in sporadic scirrhous-type gastric cancer cells.

Scirrhous-type gastric carcinoma (SGC), which is characterized by the rapid proliferation of cancer cells accompanied by extensive fibrosis, shows extremely poor survival. A reason for the poor prognosis of SGC is that the driver gene responsible for SGC has not been identified. To identify the characteristic driver gene of SGC, we examined the genomic landscape of six human SGC cell lines of OCUM-1, OCUM-2M, OCUM-8, OCUM-9, OCUM-12 and OCUM-14, using multiplex gene panel testing by next-generation sequencing. In this study, the non-synonymous mutations of serine threonine kinase 11/liver kinase B1 (STK11/LKB1) gene were detected in OCUM-12, OCUM-2M and OCUM-14 among the six SGC cell lines. Capillary sequencing analysis confirmed the non-sense or missense mutation of STK11/LKB1 in the three cell lines. Western blot analysis showed that LKB1 expression was decreased in OCUM-12 cells and OCUM-14 cells harboring STK11/LKB1 mutation. The mammalian target of rapamycin (mTOR) inhibitor significantly inhibited the proliferation of OCUM-12 and OCUM-14 cells. The correlations between STK11/LKB1 expression and clinicopathologic features of gastric cancer were examined using 708 primary gastric carcinomas by immunochemical study. The low STK11/LKB1 expression group was significantly associated with SGC, high invasion depth and frequent nodal involvement, in compared with the high STK11/LKB1 expression group. Collectively, our study demonstrated that STK11/LKB1 mutation might be responsible for the progression of SGC, and suggested that mTOR signaling by STK11/LKB1 mutation might be one of therapeutic targets for patients with SGC.

Circulating tumor cells with FGFR2 expression might be useful to identify patients with existing FGFR2-overexpressing tumor.

Fibroblast growth factor receptor (FGFR) is associated with proliferation, migration, and angiogenesis of carcinomas, and FGFR signaling inhibitors are considered a key drug for the treatment of solid tumors with FGFR overexpression. Amplification of FGFR2 is reportedly identified in 3%-10% of gastric cancers (GCs). The aim of this study is to clarify whether the identification of the circulating tumor cells (CTCs) with FGFR2 overexpression is useful to detect patients with FGFR2-overexpressing GC. One hundred GC patients who underwent gastrectomy were enrolled. A total volume of 8 mL of peripheral blood was collected from each patient just before gastrectomy, and mononuclear cells were enriched by Ficol density gradient centrifugation. These cells were immunostained with PI/CD45/EpCAM/FGFR2. The number of CTCs with FGFR2 expression in each sample was enumerated by FACScan. The FGFR2 expression level of the resected primary tumor was assessed by immunohistochemistry. The number of FGFR2-positive CTCs in the GC patients' peripheral blood was significantly correlated with the FGFR2 expression level of the primary GC. The relapse-free survival of the patients with FGFR2-positive CTCs (≥5 cells/10 mL blood) was significantly poorer (P = .018, log-rank) than that of the patients without FGFR2-positive CTCs (<5 cell/10 mL blood). These findings suggested that the determination of FGFR2-positive CTCs might help identify an existing tumor with FGFR2 overexpression.

[Experience with Using the EnCor ENSPIRE®System in Mammary Tissue Biopsy].

We investigated the usefulness of vacuum-assisted biopsy(VAB)using the EnCor ENSPIRE®system for initial biopsy of breast tumors. We analyzed 24 cases of VAB using the EnCor ENSPIRE®system performed for breast tumors. Of 24 mammary lesions, 12 cases(50.0%)were diagnosed as malignant. Among them, 7 cases(29.2%)were invasive ductal carcinoma(IDC) and 5 cases(20.8%)were ductal carcinoma in situ(DCIS). Six cases required tumor resection for definitive diagnosis; 1 case was diagnosed with IDC, 2 cases with DCIS, 2 cases with intraductal papilloma(IDP), and 1 case with atypical ductal hyperplasia( ADH). Moreover, EnCor ENSPIRE®system biopsy was performed in 15 cases because malignancy could not be diagnosed using core needle biopsy. There were 4 cases of IDC, 4 cases of DCIS, 2 cases of IDP, 2 cases of usual ductal hyperplasia, and 2 cases of ADH. There were no complications due to a series of procedures. We believe that the EnCor ENSPIRE®system is an effective technique having both convenience and great diagnostic accuracy.

Two families with gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS): case reports and literature review.

Background: Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), a hereditary gastric polyposis syndrome that presents with fundic gastric polyposis, is associated with an increased risk of gastric adenocarcinoma. The four patterns of point mutation in the adenomatous polyposis coli (APC) promoter 1B region have been identified as the cause of GAPPS. GAPPS was first reported in 2012, and only 33 families with GAPPS have been reported worldwide to date. Therefore, the clinical management for GAPPS are still controversial. We herein report two unrelated GAPPS families with the same point mutation site. Case Description: Total seven patients of two families had >100 carpeting polyps in the gastric body and fundus, and one of them (69-year-old female) had gastric adenocarcinoma. As a result of germline analysis, both families harbored a point mutation (c.-192A>G) in APC promoter 1B region, previously reported in only one family. Three of seven patients underwent total gastrectomy, and others were followed-up with regular esophagogastroduodenoscopy (EGD) and biopsy every 6 months. To summarize the reported cases, total 42 patients of 35 families have developed gastric adenocarcinoma. Conclusions: This report may contribute to determining the appropriate guidelines for the clinical practice of GAPPS. When EGD reveals gastric polyposis localized to the gastric body and fundus, it is important to obtain a detailed family history and perform germline mutational analysis. And more, point mutation type of our family cases was a rare pattern, suggested that c.-192A>G pattern might be a pathogenic variant.

Establishment of a gastric cancer cell line with high microsatellite instability, OCUM-13, derived from Borrmann type-2 primary tumor.

Gastric cancer (GC) with microsatellite instability (MSI) has been reported to be sensitive to immunotherapy, however some of GC cases with MSI remain resistant to immunotherapy. Cancer cell lines showing MSI might be useful for the analysis of mechanisms of immunotherapy, while only a few GC cell lines with MSI are available so far. In this study, we established a unique GC cell line with MSI, OCUM-13, from a primary GC with abundant tumor-infiltrating lymphocytes. MSI assay indicated that OCUM-13 cells as well as the primary tumor showed a band shift in more than 3 of 5 microsatellite loci, suggesting that OCUM-13 did have high MSI. The subcutaneous inoculation of OCUM-13 cells into mice performed tumor formation. Insulin-like growth factor 1 receptor inhibitor decreased the growth of OCUM-13 cells. The newly established cell line with MSI, OCUM-13, might be useful for the analysis of cancer therapy for GC with MSI.

Dipeptidyl Peptidase-4 from Cancer-associated Fibroblasts Stimulates the Proliferation of Scirrhous-type Gastric Cancer Cells.

BACKGROUND/AIM: Cancer-associated fibroblasts (CAFs) may promote the malignancy of human scirrhous gastric cancer (SGC) cells. We conducted the present study to identify novel growth factors from CAFs. MATERIALS AND METHODS: OCUM-12 and 2 CAF cell lines were used. The proliferation of cancer cells was determined by the number of cancer cells or the MTT assay. The growth factor(s) were purified and characterized by the gel filtration chromatography and protein array. RESULTS: The molecular weight of the growth-stimulating factor was estimated to be approximately 66-669 kDa. Protein array of conditioned medium (CM) from CAFs indicated that dipeptidyl peptidase-4 (DPP-4) was one of the growth factors. The addition of CM increased the phosphorylation of C-X-C chemokine receptor 4 (CXCR4). The DPP-4 inhibitor significantly inhibited the growth-stimulating activity of CM. CONCLUSION: DPP-4 from CAFs might be one of the growth-stimulating factors for SGC through CXCR4.

CXCR2 signaling might have a tumor-suppressive role in patients with cholangiocarcinoma.

BACKGROUND: We reported that chemokine C-X-C motif receptor 2 (CXCR2) signaling appears to play an important role in the pathogenic signaling of gastric cancer (GC), and although CXCR2 may have a role in other solid cancers, the significance of CXCR2 in cholangiocarcinoma (CCA) has not been evaluated. Herein, we determined the clinicopathologic significance of CXCL1-CXCR2 signaling in CCA. MATERIALS AND METHODS: Two human CCA cell lines, OCUG-1 and HuCCT1, were used. CXCR2 expression was examined by western blotting. We investigated the effects of CXCL1 on the proliferation (by MTT assay) and migration activity (by a wound-healing assay) of each cell line. Our immunohistochemical study of the cases of 178 CCA patients examined the expression levels of CXCR2 and CXCL1, and we analyzed the relationship between these expression levels and the patients' clinicopathologic features. RESULTS: CXCR2 was expressed on both CCA cell lines. CXCL1 significantly inhibited both the proliferative activity and migratory activity of both cell lines. CXCL1 and CXCR2 were immunohistochemically expressed in 73% and 18% of the CCA cases, respectively. The CXCL1-positive group was significantly associated with negative lymph node metastasis (p = 0.043). The CXCR2-positive group showed significantly better survival (p = 0.042, Kaplan-Meier). A multivariate logistic regression analysis revealed that CXCR2 expression (p = 0.031) and lymph node metastasis (p = 0.004) were significantly correlated with the CCA patients' overall survival. CONCLUSION: CXCR2 signaling might exert a tumor-suppressive effect on CCA cells. CXCR2 might be a useful independent prognostic marker for CCA patients after surgical resection.

Candidate Oncogenes, ARHGAP4, NOS3, and OR51B5, for the Development of Scirrhous-type Gastric Cancer.

BACKGROUND/AIM: Scirrhous-type gastric cancer (SGC), one of the most intractable cancer subtypes, is characterized by rapid cancer cell proliferation and infiltration accompanied by extensive stromal fibrosis. One of the reasons for its poor prognosis may be the lack of molecular target drugs for SGC, because of the unknown driver genes. Exploration of somatic mutations in the human samples of SGC using next-generation sequencing (NGS) has been hampered by abundant fibrous tissues in these samples. Therefore, this study aimed to determine a novel oncogene by RNA-sequencing using SGC cell lines, avoiding contamination with fibrosis. MATERIALS AND METHODS: In silico analysis of RNA-sequencing public data of the gastric cancer cell line, and RNA- sequencing using five of our unique SGC cell lines, OCUM1, OCUM2MLN, OCUM8, OCUM12, and OCUM14 were performed. RESULTS: We found three differentially expressed genes, ARHGAP4, NOS3, and OR51B5 that are significantly over-expressed in SGC cells. Immunohistochemical analysis indicated that the protein expression levels of these three genes were significantly higher in SGC than in other types of gastric cancer. The prognosis of patients with positive expression of these three genes was significantly poorer than those with negative expression. In particular, ARHGAP4 expression was an independent predictor of poor prognosis and recurrence. CONCLUSION: ARHGAP4, NOS3, and OR51B5 may be candidate driver genes for SGC. ARHGAP4 may be a promising molecular target for SGC.

Gastric cancer stem cells survive in stress environments via their autophagy system.

Cancer stem cells (CSCs) play an important role in the progression of carcinoma and have a high potential for survival in stress environments. However, the mechanisms of survival potential of CSCs have been unclear. The aim of this study was to clarify the significance of autophagy systems of CSCs under stress environments. Four gastric cancer cell line were used. Side population (SP) cells were sorted from the parent cells, as CSC rich cells. The expression of stem cell markers was examined by RT-PCR. The viability of cancer cells under starvation and hypoxia was evaluated. The expression level of the autophagy molecule LC3B-II was examined by western blot. The numbers of autophagosomes and autolysosomes were counted by electron microscope. SP cells of OCUM-12 showed a higher expression of stem cell markers and higher viability in starvation and hypoxia. Western blot and electron microscope examinations indicated that the autophagy was more induced in SP cells than in parent cells. The autophagy inhibitor significantly decreased the viability under the stress environments. These findings suggested that Cancer stem cells of gastric cancer might maintain their viability via the autophagy system. Autophagy inhibitors might be a promising therapeutic agent for gastric cancer.

Clinicopathologic significance of TROP2 and phospho-TROP2 in gastric cancer.

Trophoblast cell-surface antigen 2 (TROP2) is a transmembrane glycoprotein expressed in epithelial cells. Increased TROP2 expression has been reported to be associated with malignant progression in most carcinomas; however, TROP2 has a tumor-suppressive function in certain types of cancer. Since the function of TROP2 is controversial, the present study subsequently aimed to clarify the clinicopathologic significance of TROP2 and pTROP2 expression in human gastric cancer (GC). The cases of 704 patients with GC who underwent gastrectomy were retrospectively analyzed. The expression levels of TROP2 and pTROP2 in each tumor were evaluated by immunohistochemistry. The association between the clinicopathologic features of patients with GC and the levels of TROP2 and pTROP2 in their tumors was analyzed. Increased TROP2 and pTROP2 expression was identified in 330 (46.9%) and 306 (43.5%) of the 704 patients with GC, respectively. Increased TROP2 expression was associated with the histological intestinal type, high tumor invasion depth (T3/T4), lymph node metastasis, lymphatic invasion and venous invasion. By contrast, increased pTROP2 expression was associated with intestinal type, low tumor invasion depth (T1/2), no lymph node metastasis and no lymphatic invasion. Increased TROP2 expression was associated with poorer overall survival (OS) (P<0.01; log rank test), whereas increased pTROP2 expression was significantly associated with improved OS (P<0.01; log rank test). In conclusion, increased expression levels of TROP2, but not pTROP2, may be associated with the metastatic ability of GC, resulting in poor prognosis of patients with GC.

EMMPRIN in extracellular vesicles from peritoneal mesothelial cells stimulates the invasion activity of diffuse-type gastric cancer cells.

Peritoneal metastasis of gastric cancer (GC) results in extremely poor prognoses. The peritoneal cavity is covered by a monolayer of peritoneal mesothelial cells (PMCs). Interactions between GC cells and PMCs might play a pivotal role in peritoneal metastasis. Extracellular vesicles (EVs) correlate with intercellular communication. Although intercellular communication between cancer cells and PMCs might be associated with the peritoneal metastatic process, the role of EVs from PMCs remains unclear. We investigated the effects of EVs from PMCs on GC cells. Three GC cell lines (OCUM-12, NUGC-3, and MKN74) and four mesothelial cell lines were used. The effects of EVs derived from the PMCs on the invasion and migration of GC cells were evaluated by Matrigel invasion assay. Factors contained in the PMC EVs were analyzed; extra-cellular matrix metalloproteinase inducer (EMMPRIN) was detected in the EVs. The effects of an EMMPRIN inhibitor on the invasion-stimulating activity of EVs were examined. The EMMPRIN expressions of 110 GCs were evaluated by immunohistochemistry. PMC EVs significantly promoted the invasion of diffuse-type GC cells, i.e., OCUM-12 and NUGC-3 cells. EMMPRIN in the EVs stimulated the invasion of OCUM-12 and NUGC-3 cells. The invasion-stimulating activity of PMC EVs was inhibited by the EMMPRIN inhibitor. A high EMMPRIN expression in PMCs was significantly associated with worse cancer-specific survival and peritoneal-recurrence-free survival. EMMPRIN in EVs from PMCs might stimulate the malignant progression of diffuse-type GC. EMMPRIN might be a useful prognostic marker of recurrence in GC patients.

Clinical difference between fibroblast growth factor receptor 2 subclass, type IIIb and type IIIc, in gastric cancer.

Fibroblast growth factor receptor 2 (FGFR2) has two isoforms: IIIb type and IIIc type. Clinicopathologic significance of these two FGFR2 subtypes in gastric cancer remains to be known. This study aimed to clarify the clinicopathologic difference of FGFR2IIIb and/or FGFR2IIIc overexpression. A total of 562 patients who underwent gastrectomy was enrolled. The expressions of FGFR2IIIb and FGFR2IIIc were retrospectively examined by immunohistochemistry or fluorescence in situ hybridization (FISH) using the 562 gastric tumors. We evaluated the correlation between clinicopathologic features and FGFR2IIIb overexpression and/or FGFR2IIIc overexpression in gastric cancer. FGFR2IIIb overexpression was observed in 28 cases (4.9%), and FGFR2IIIc overexpression was observed in four cases (0.7%). All four FGFR2IIIc cases were also positive for FGFR2IIIb, but not in the same cancer cells. FGFR2IIIb and/or FGFR2IIIc overexpression was significantly correlated with lymph node metastasis and clinical stage. Both FGFR2IIIb and FGFR2IIIc were significantly associated with poor overall survival. A multivariate analysis showed that FGFR2IIIc expression was significantly correlated with overall survival. FISH analysis indicated that FGFR2 amplification was correlated with FGFR2IIIb and/or FGFR2IIIc overexpression. These findings suggested that gastric tumor overexpressed FGFR2IIIc and/or FGFR2IIIb at the frequency of 4.9%. FGFR2IIIc overexpression might be independent prognostic factor for patients with gastric cancer.

SDF1α/CXCR4 axis may be associated with the malignant progression of gastric cancer in the hypoxic tumor microenvironment.

Stromal cell-derived factor 1α (SDF1α) and its receptor C-X-C chemokine receptor type 4 (CXCR4) have been reported to form an important chemokine signaling pathway. Our previous study reported that SDF1α from tumor stromal cells may stimulate the proliferation of gastric cancer (GC) cells through the CXCR4 axis in a hypoxic microenvironment. However, a limited number of studies have addressed the clinicopathological significance of the expression of SDF1α and CXCR4 in GC, particularly at hypoxic regions. Immunohistochemistry was used to investigate the expression levels of SDF1α, CXCR4 and the hypoxic marker carbonic anhydrase 9 (CA9) in 185 patients with stage II and III GC. The results demonstrated that CA9 was expressed on cancer and stromal cells in hypoxic lesions, CXCR4 was mainly expressed in cancer cells, and SDFα was mainly expressed in stromal cells. CXCR4 expression in cancer cells and SDFα expression in stromal cells were associated with the hypoxic regions with CA9 expression. The CA9 and CXCR4 expression in the cancer cells, and the SDF1α expression in the stromal cells (CA9/CXCR4/SDF1α) was significantly associated with macroscopic type 4 tumor (P=0.012) and the pattern of tumor infiltration into the surrounding tissue (P<0.001). The prognosis of the all CA9/CXCR4/SDF1α-positive patients was significantly poorer compared with that of patients with CA9-, CXCR4- or SDF1α-negative GC at Stage III (P=0.041). These results indicated that hypoxia may upregulate SDFα production in stromal cells and CXCR4 expression in cancer cells. The SDF1α/CXCR4 axis may serve an important role in the progression of GC.

The clinicopathologic significance of Tks5 expression of peritoneal mesothelial cells in gastric cancer patients.

BACKGROUND: Gastric cancer (GC) patients frequently develop peritoneal metastasis. Recently, it has been reported that peritoneal mesothelial cells (PMCs) activated by GC cells acquire a migratory capacity and promote GC cell invasion. The invasiveness of PMCs reportedly depends on the activity of Tks5, an adaptor protein required for invadopodia formation. However, the relationship between clinicopathologic features and Tks5 expression in PMCs has been poorly documented. In this study, we evaluated the clinicopathologic significance of the Tks5 expression of PMCs in GC patients. MATERIALS AND METHODS: A total of 110 GC patients who underwent gastrectomy were enrolled in this study. Tks5 expressions in PMCs from the greater omentum, lesser omentum and retroperitoneum were evaluated by immunohistochemistry. We analyzed the correlation between Tks5 expressions in PMCs and the patients' clinicopathologic features. RESULTS: Tks5 expression was found in 71 (64.5%) of the 110 patients, while 39 (35.5%) were Tks5-negative. Tks5 positivity was significantly (p = 0.038) associated with a greater tumor depth (i.e., T3/4 compared with T1/T2). Peritoneal recurrence was found in 12 of 98 cases within 3 years of surgery. The 3-year peritoneal recurrence-free survival (PRFS) rate in Tks5-positive cases was significantly poorer than that in Tks5-negative cases (80.1% vs 97.4%, p = 0.024). Multivariate analysis revealed that Tks5 positivity and lymph node metastasis were independent factors for PRFS. CONCLUSION: Tks5 is frequently expressed in PMCs in advanced-stage gastric cancer. Tks5 might be a useful predictor for peritoneal recurrence in GC patients.

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

[This corrects the article DOI: 10.1371/journal.pone.0225958.].

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.

The Clinicopathological Significance of the CXCR2 Ligands, CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, and CXCL8 in Gastric Cancer.

BACKGROUND/AIM: We have previously reported that chemokine (C-X-C motif) receptor 2 (CXCR2) signaling was associated with the malignant progression of gastric cancer (GC). We thus examined the clinicopathological significance of CXCR2 ligands, CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, and CXCL8, in GC. PATIENTS AND METHODS: The expression of CXCR2 ligands in 590 GC cases was investigated by immunohistochemistry. RESULTS: The expression was as follows: CXCL1, 46.2% (257/557); CXCL2, 20.7% (122/590); CXCL3, 17.1% (101/589); CXCL5/CXCL6, 2.9% (17/589); CXCL7, 36.4% (215/590); and CXCL8 1.7% (10/585) of the cases. High invasion depth was correlated with CXCL1 expression. Lymph node metastasis and peritoneal cytology positivity were correlated with high expression of CXCL1 and CXCL7. The prognoses of the CXCL1-positive patients were significantly poorer than those of the CXCL1-negative patients (p<0.001). CONCLUSION: Among the CXCR2 ligands, CXCL7 and especially CXCL1, might play an important role in the malignant progression of GC via CXCR2 signaling.