Retrospective analysis of prognosis for scirrhous-type gastric cancer: one institution's experience

Long Noncoding RNA HOTAIR Promotes Epithelial-Mesenchymal Transition and Is a Suitable Target to Inhibit Peritoneal Dissemination in Human Scirrhous Gastric Cancers

OBJECTIVES

Scirrhous gastric cancer, which accounts for approximately 10% of all gastric cancers, often disseminates to the peritoneum, leading to intractable cases with poor prognosis. There is an urgent need for new treatment approaches for this difficult cancer.

METHODS

We previously established an original cell line, HSC-60, from a scirrhous gastric cancer patient and isolated a peritoneal-metastatic cell line, 60As6, in nude mice following orthotopic inoculations. In the present study, we focused on the expression of long noncoding ribonucleic acid (RNA) (lncRNA) in the cell lines and investigated the mechanism on peritoneal dissemination.

RESULTS

We demonstrated that an lncRNA, HOX transcript antisense RNA (HOTAIR), is expressed significantly more highly in 60As6 than HSC-60 cells. Then, using both HOTAIR knockdown and overexpression experiments, we showed that high-level expression of HOTAIR promotes epithelial-mesenchymal transition (EMT) in 60As6 cells. By luciferase assay, we found that HOTAIR directly targets and binds to miR-217, and that miR-217 directly binds to Zinc finger E-box-binding homeobox 1 (ZEB1). The knockdown of HOTAIR in 60As6 cells significantly reduced the invasion activity and peritoneal dissemination - and significantly prolonged the survival - in the orthotopic tumor mouse model.

CONCLUSION

An EMT-associated pathway (the HOTAIR-miR-217-ZEB1 axis) appears to inhibit peritoneal dissemination and could lead to a novel therapeutic strategy against scirrhous gastric cancer in humans.

Efficacy of a Third-Generation Oncolytic Herpes Virus G47Δ in Advanced Stage Models of Human Gastric Cancer

Advanced gastric cancer, especially scirrhous gastric cancer with peritoneal dissemination, remains refractory to conventional therapies. G47Δ, a third-generation oncolytic herpes simplex virus type 1, is an attractive novel therapeutic agent for solid cancer. In this study, we investigated the therapeutic potential of G47Δ for human gastric cancer. In vitro, G47Δ showed good cytopathic effects and replication capabilities in nine human gastric cancer cell lines tested. In vivo, intratumoral inoculations with G47Δ (2 × 10⁵ or 1 × 10⁶ plaque-forming units [PFU]) significantly inhibited the growth of subcutaneous tumors (MKN45, MKN74, and 44As3). To evaluate the efficacy of G47Δ for advanced-stage models of gastric cancer, we generated an orthotopic tumor model and peritoneal dissemination models of human scirrhous gastric cancer (MKN45-luc and 44As3Luc), which have features mimicking intractable scirrhous cancer patients. G47Δ (1 × 10⁶ PFU) was constantly efficacious whether administered intratumorally or intraperitoneally in the clinically relevant models. Notably, G47Δ injected intraperitoneally readily distributed to, and selectively replicated in, disseminated tumors. Furthermore, flow cytometric analyses of tumor-infiltrating cells in subcutaneous tumors revealed that intratumoral G47Δ injections markedly decreased M2 macrophages while increasing M1 macrophages and natural killer (NK) cells. These findings indicate the usefulness of G47Δ for treating human gastric cancer, including scirrhous gastric cancer and the ones in advanced stages.

Endoscopic ultrasound-guided fine-needle aspiration used in diagnosing gastric linitis plastica: Metastatic lymph nodes can be valuable targets

BACKGROUND AND AIM

The aim of this study was to assess the performance of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for the diagnosis of gastric linitis plastic (GLP).

METHODS

We retrospectively reviewed all the cases undergoing EUS for suspected GLP from January 2012 to September 2017. We included patients with GLP confirmed pathologically with white-light endoscopy (WLE)-guided biopsy or EUS-FNA. Diagnostic value of WLE biopsy and EUS-FNA was further analyzed.

RESULTS

A total of 107 cases of suspected GLP were referred for EUS examination in our center. Twenty-six patients were eligible and included. GLP was confirmed in 15 cases by EUS-FNA, nine cases by WLE biopsy, and eight cases by surgical pathology. The positive rate of EUS-FNA and WLE biopsy for involved gastric wall was 71.43% (15/21) and 47.37% (9/19). EUS-FNA of metastatic lymph nodes was also performed in 16 cases, and 15 (93.75%) were proved to be malignant, including all 13 that were positive for peri-gastric lymph nodes, and two of three (66.67%) that were positive rate for retroperitoneal lymph nodes. Diameters of punctured lymph nodes ranged from 3.30 to 22.70 mm, with an average of 12.12 mm.

CONCLUSIONS

Pathological diagnosis of GLP by invasive endoscopy is still intractable, even at a late stage. Positive results can be obtained even in small or distant lymph nodes.

Identification and Characterization of CXCR4-Positive Gastric Cancer Stem Cells

Diffuse-type solid tumors are often composed of a high proportion of rarely proliferating (i.e., dormant) cancer cells, strongly indicating the involvement of cancer stem cells (CSCs) Although diffuse-type gastric cancer (GC) patients have a poor prognosis due to high-frequent development of peritoneal dissemination (PD), it is limited knowledge that the PD-associated CSCs and efficacy of CSC-targeting therapy in diffuse-type GC. In this study, we established highly metastatic GC cell lines by in vivo selection designed for the enrichment of PD-associated GC cells. By microarray analysis, we found C-X-C chemokine receptor type 4 (CXCR4) can be a novel marker for highly metastatic CSCs, since CXCR4-positive cells can grow anchorage-independently, initiate tumors in mice, be resistant to cytotoxic drug, and produce differentiated daughter cells. In clinical samples, these CXCR4-positive cells were found from not only late metastasis stage (accumulated ascites) but also earlier stage (peritoneal washings). Moreover, treatment with transforming growth factor-β enhanced the anti-cancer effect of docetaxel via induction of cell differentiation/asymmetric cell division of the CXCR4-positive gastric CSCs even in a dormant state. Therefore, differentiation inducers hold promise for obtaining the maximum therapeutic outcome from currently available anti-cancer drugs through re-cycling of CSCs.

Endoscopic ultrasound-guided deep and large biopsy for diagnosis of gastric infiltrating tumors with negative malignant endoscopy biopsies

AIM: To assess the diagnostic yield and safety of a deep and large biopsy technique under the guidance of endoscopic ultrasound (EUS) for diagnosis of gastric infiltrating tumors with negative malignant endoscopy biopsies.

METHODS: From January 2009 to March 2014, 36 patients in whom gastric infiltrating tumors had been diagnosed by EUS received negative results for malignancy after endoscopic biopsies. The deep and large biopsy technique combined bite-on-bite technique with or without endoscopic mucosal resection (EMR) to obtain submucosal tissue from lesions. EUS was used to select the appropriate biopsy sites. If the lesion protruded into the cavity, EMR was performed for removal of the overlying mucosa and then bite-on-bite technique was conducted in the resected area to obtain submucosal tissue. If the lesion appeared to be flat or was difficult to lift by injection, the bite-on-bite technique was directly used.

RESULTS: Twenty-eight of the 36 patients were treated by EMR followed by bite-on-bite technique, while 8 patients only underwent bite-on-bite technique. Histological results showed 23 of the 36 lesions were poorly differentiated adenocarcinomas, 2 diffuse large B cell lymphomas, 4 mucosa-associated lymphoid tissue-type lymphomas, and 7 undiagnosed. The deep and large biopsy technique provided a definitive and conclusive diagnosis in 29 (80.6%) of the 36 patients. The 12 gastric linitis plastica and 6 lymphoma patients received chemotherapy and avoided surgery. Minor oozing of blood in 2 mucosal resection wounds was managed by argon plasma coagulation and in 5 cases after deep biopsies by epinephrine (0.001%). Neither severe hemorrhage nor perforation occurred in any patient.

CONCLUSION: The deep and large biopsy technique is superior to ordinary endoscopic biopsy for achieving an accurate diagnosis of gastric infiltrating tumors. This procedure guided by EUS is an effective and safe diagnostic method for gastric infiltrating tumors in which endoscopic biopsy results were negative for malignancy.

Type-specific diagnosis and evaluation of longitudinal tumor extent of borrmann type IV gastric cancer: CT versus gastroscopy

Objective

To compare the accuracy of computed tomography (CT) with that of gastroscopy for the extent of evaluation of longitudinal tumor and type-specific diagnosis of Borrmann type IV gastric cancer.

Materials and Methods

Fifty-nine patients (35 men with mean age of 60 years and 24 women with mean age of 55 years) who underwent surgical resection of Borrmann type IV gastric cancer were included in this study. Histopathological analysis data was used as a reference standard to confirm the clinical interpretations of gastroscopy and CT for the diagnosis of Borrmann type IV and evaluation of longitudinal tumor extent. For the evaluation of longitudinal extent, gastroscopic and CT results were classified as underestimated, accurate, or overestimated. The McNemar test was used to identify statistically significant differences in the accuracy between gastroscopy and CT.

Results

For the diagnosis of Borrmann type IV gastric cancer, the accuracy of CT was significantly higher than that of gastroscopy (74.6% [44/59] vs. 44.1% [26/59], p < 0.001). CT was significantly more accurate in assessing the overall tumor extent than gastroscopy (61.4% [35/57] vs. 28.1% [16/57], p < 0.001). The proximal (75.4% [43/57] vs. 50.9% [29/57], p = 0.003) and distal tumor extent (71.9% [41/57] vs. 43.9% [25/57], p < 0.05) were more accurately predicted by CT compared with gastroscopy. The underestimation of tumor extent was a major source of error in both examinations.

Conclusion

CT was found to be more predictive than gastroscopy in type-specific diagnosis and the evaluation of longitudinal tumor extent in patients with Borrmann type IV gastric cancer.

Intraperitoneal delivery of a small interfering RNA targeting NEDD1 prolongs the survival of scirrhous gastric cancer model mice

The prognosis of patients with advanced diffuse-type gastric cancer (GC), especially scirrhous gastric cancer (SGC) remains extremely poor. Peritoneal carcinomatosis is a frequent form of metastasis of SGC. With survival rates of patients with peritoneal metastasis at 3 and 5 years being only 9.8% and 0%, respectively, development of a new treatment is urgently crucial. For such development, the establishment of a therapeutic mouse model is required. Among the 11 GC cell lines we examined, HSC-60 showed the most well-preserved expression profiles of the Hedgehog and epithelial-mesenchymal transition pathways found in primary SGCs. After six cycles of harvest of ascitic tumor cells and their orthotopic inoculation in scid mice, a highly metastatic subclone of HSC-60, 60As6 was obtained, by means of which we successfully developed peritoneal metastasis model mice. The mice treated with small interfering (si) RNA targeting NEDD1, which encodes a gamma-tubulin ring complex-binding protein, by the atelocollagen-mediated delivery system showed a significantly prolonged survival. Our mouse model could thus be useful for the development of a new therapeutic modality. Intraperitoneal administration of siRNAs of targeted genes such as NEDD1 could provide a new opportunity in the treatment of the peritoneal metastasis of SGC.

Biological significance of localized Type IV scirrhous gastric cancer

The prognosis of type IV scirrhous gastric cancer (SGC) is extremely poor. Linitis plastica (LP), the so-called 'leather bottle stomach', is believed to be a typical case of SGC, which is usually diagnosed as a far-advanced gastric cancer. The pathogenesis of this disease remains unclear. Although typical SGC often invades the entire stomach, atypical cases show SGC localized to one region of the stomach. The aim of the present study was to investigate localized SGC (LSGC) and its biological significance. A total of 509 patients with advanced gastric cancer who underwent gastrectomy were evaluated. These patients were divided into three groups as follows: 19 patients with type IV scirrhous lesions invading the whole stomach (defined as LP), 60 patients with type IV scirrhous lesions localized in less than two thirds of the stomach (defined as LSGC) and the remaining 430 patients with all other types of gastric cancer (OGC), and then clinicopathologically compared. Results showed that LP had deeper invasion (p=0.006), more frequent peritoneal dissemination including positive cytology (p=0.01 and p=0.018) and lower curability (p=0.03) compared with LSGC, whereas LSGC showed a higher malignant potential in a number of clinicopathological factors compared with OGC. Univariate analysis showed that survival in patients with LP was significantly poorer than in those with LSGC (p=0.002) whose survival was, in turn, inferior to those with OGC. By contrast, LSGC was not a prognostic factor in SGC according to the multivariate analysis. The findings of this study suggested that the malignant status of LSGC differs from that of LP, and that curative gastrectomy is effective in improving the outcome for LSGC but not for LP, as LSGC may represent the prelinitis condition.

Resequencing and copy number analysis of the human tyrosine kinase gene family in poorly differentiated gastric cancer

The tyrosine kinase (TK) family is an important regulator of signaling pathways that control a variety of physiological and pathological conditions, and a substantial proportion of TK genes are genetically altered in cancer. To clarify the somatic mutation profile of TK genes and discover potential targets for gastric cancer (GC) therapy, we undertook a systematic screening of mutations in the kinase domains of all human TK genes (636 exons of 90 genes) in 17 GC cell lines and 52 microdissected primary GCs with poorly differentiated histology. We identified 26 non-synonymous alterations (22 genes in total) that included 11 sequence alterations in cell lines and 15 somatic mutations in primary tumors. Recurrent mutations were found in four genes including a known oncogene (NTRK3), the Src kinase family (LTK and CSK) and a potential Wnt signal activator (ROR2). In addition, we analyzed copy number alterations of all the TK gene loci in the same cohort samples by array-based comparative genomic hybridization analysis and identified 24 high-level amplifications and two homozygous deletions. Both sequence alteration and frequent copy number aberration were detected in two TK genes (HCK and ERBB2), strongly suggesting that they encode potential oncogenes in GC. Our focused and integrated analyses of systemic resequencing and gene copy number have revealed the novel onco-kinome profile of GC and pave the way to a comprehensive understanding of the GC genome.

Recent results of therapy for scirrhous gastric cancer

The prognosis of patients with scirrhous gastric cancer (SGC) is extremely poor. However, recent advances in therapeutic strategies against SGC, using effective anticancer drugs, have prolonged the survival of patients with SGC. This paper reviews the recent therapeutic outcomes of this type of gastric cancer and introduces a new treatment protocol for SGC.