Pathology and Pathogenesis of Metabolic Dysfunction-Associated Steatotic Liver Disease-Associated Hepatic Tumors.

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive fat accumulation in the livers of patients without a history of alcohol abuse. It is classified as either simple steatosis (nonalcoholic fatty liver) or nonalcoholic steatohepatitis (NASH), which can progress to liver cirrhosis and hepatocellular carcinoma (HCC). Recently, it was suggested that the terms "metabolic dysfunction-associated steatotic liver disease (MASLD)" and "metabolic dysfunction-associated steatohepatitis (MASH)" should replace the terms "nonalcoholic fatty liver disease (NAFLD)" and "nonalcoholic steatohepatitis (NASH)", respectively, with small changes in the definitions. MASLD, a hepatic manifestation of metabolic syndrome, is rapidly increasing in incidence globally, and is becoming an increasingly important cause of HCC. Steatohepatitic HCC, a histological variant of HCC, is characterized by its morphological features resembling non-neoplastic steatohepatitis and is closely associated with underlying steatohepatitis and metabolic syndrome. Variations in genes including patatin-like phospholipase domain-containing protein 3 (PNPLA3), transmembrane 6 superfamily 2 (TM6SF2), and membrane-bound O-acyltransferase domain-containing protein 7 (MBOAT7) are associated with the natural history of MASLD, including HCC development. The mechanisms of HCC development in MASLD have not been fully elucidated; however, various factors, including lipotoxicity, inflammation, reactive oxygen species, insulin resistance, and alterations in the gut bacterial flora, are important in the pathogenesis of MASLD-associated HCC. Obesity and MASLD are also recognized as risk factors for hepatocellular adenomas, and recent meta-analyses have shown an association between MASLD and intrahepatic cholangiocarcinoma. In this review, we outline the pathology and pathogenesis of MASLD-associated liver tumors.

Artificial intelligence and deep learning: New tools for histopathological diagnosis of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) is associated with metabolic syndrome and is rapidly increasing globally with the increased prevalence of obesity. Although noninvasive diagnosis of NAFLD/NASH has progressed, pathological evaluation of liver biopsy specimens remains the gold standard for diagnosing NAFLD/NASH. However, the pathological diagnosis of NAFLD/NASH relies on the subjective judgment of the pathologist, resulting in non-negligible interobserver variations. Artificial intelligence (AI) is an emerging tool in pathology to assist diagnoses with high objectivity and accuracy. An increasing number of studies have reported the usefulness of AI in the pathological diagnosis of NAFLD/NASH, and our group has already used it in animal experiments. In this minireview, we first outline the histopathological characteristics of NAFLD/NASH and the basics of AI. Subsequently, we introduce previous research on AI-based pathological diagnosis of NAFLD/NASH.

In vitro synthesis of mucin-type O-glycans using saccharide primers comprising GalNAc-Ser and GalNAc-Thr residues.

Mucin-type O-glycosylation of serine or threonine residue in proteins is known to be one of the major post-translational modifications. In this study, two novel alkyl glycosides, Nα-lauryl-O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-l-serineamide (GalNAc-Ser-C12) and Nα-lauryl-O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-l-threonineamide (GalNAc-Thr-C12) were synthesized as saccharide primers to prime mucin-type O-glycan biosynthesis in cells. Upon incubating human gastric cancer MKN45 cells with the saccharide primers, 22 glycosylated products were obtained, and their structures were analyzed using liquid chromatography-mass spectrometry and enzyme digestion. The amounts of glycosylated products were dependent on the amino acid residues in the saccharide primers. For example, in vitro synthesis of T antigen (Galß1-3GalNAc), fucosyl-T (Fucα1-2Galß1-3GalNAc), and sialyl-T (NeuAcα2-3Galß1-3GalNAc) preferred a serine residue, whereas sialyl-Tn (NeuAcα2-6GalNAc) preferred a threonine residue. Furthermore, the glycosylated products derived from GalNAc-Ser/Thr-C12 and Gal-GalNAc-Ser/Thr-C12 using cell-free synthesis showed the same amino acid selectivity as those in the cell experiments. These results indicate that glycosyltransferases involved in the biosynthesis of mucin-type O-glycans distinguish amino acid residues conjugated to GalNAc. The saccharide primers developed in this study might be useful for comparing mucin-type oligosaccharides in cells and constructing oligosaccharide libraries to study cell function.

Application of Immunohistochemistry in the Pathological Diagnosis of Liver Tumors.

Although radiological diagnostics have been progressing, pathological diagnosis remains the most reliable method for diagnosing liver tumors. In some cases, definite pathological diagnosis cannot be obtained by histological evaluation alone, especially when the sample is a small biopsy; in such cases, immunohistochemical staining is very useful. Immunohistochemistry is the most frequently used technique for molecular pathological diagnosis due to its broad application, ease of performance and evaluation, and reasonable cost. The results occasionally reflect specific genetic mutations. The immunohistochemical markers of hepatocellular carcinoma include those of hepatocellular differentiation-such as hepatocyte paraffin 1 and arginase-1-and those of malignant hepatocytes-such as glypican-3, heat shock protein 70, and glutamine synthetase (GS). To classify the subtypes of hepatocellular adenoma, examination of several immunohistochemical markers, such as liver fatty acid-binding protein, GS, and serum amyloid A, is indispensable. Immunohistochemical staining for GS is also important for the diagnosis of focal nodular hyperplasia. The representative immunohistochemical markers of intrahepatic cholangiocarcinoma include cytokeratin (CK) 7 and CK19. In this article, we provide an overview of the application of immunohistochemistry in the pathological diagnosis of liver tumors referring to the association with genetic alterations. Furthermore, we aimed to explain the practical points in the differential diagnosis of liver tumors by immunohistochemical staining.

The Efficacy of Vitamin K, A Member Of Naphthoquinones in the Treatment of Cancer: A Systematic Review and Meta-Analysis.

BACKGROUND: Redox dysregulation originating from metabolic alterations in cancer cells contributes to their proliferation, invasion, and resistance to therapy. Conversely, these features represent a specific vulnerability of malignant cells that can be selectively targeted by redox chemotherapeutics. Amongst them, Vitamin K (VitK) carries the potential against cancer stem cells, in addition to the rest of tumor mass. OBJECTIVES: To assess the possible benefits and safety of VitK for cancer treatment using a systematic review and meta-analysis with a mixed-methods approach. METHODS: We performed a systematic search on several electronic databases for studies comparing VitK treatment with and without combination to the control groups. For quantitative studies, fully or partially reported clinical outcomes such as recurrence rates, survival, overall response and adverse reactions were assessed. For qualitative studies, a narrative synthesis was accomplished. RESULTS: Our analysis suggested that the clinical outcome of efficacy, the pooled hazard ratio for progression-free survival, and the pooled relative risk for overall survival, and overall response were significantly higher in the VitK therapy group compared to the placebo group (p<0.05). We did not observe any significant difference in the occurrence of adverse events between groups. Among qualitative studies, VitK treatment targeting myelodysplastic syndrome and advanced solid tumors resulted in 24.1% and 10% of clinical response, respectively. CONCLUSION: VitK not only exerts antitumor effects against a wide range of tumor types, but it also has excellent synergism with other therapeutic agents.

Effects of Caffeine and Chlorogenic Acid on Nonalcoholic Steatohepatitis in Mice Induced by Choline-Deficient, L-Amino Acid-Defined, High-Fat Diet.

Several recent experimental studies have investigated the effects of caffeine and chlorogenic acid (CGA), representative ingredients of coffee, on nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). However, the results are conflicting, and their effects are yet to be clarified. In the present study, we examined the effects of caffeine and CGA on choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD)-fed mice, relatively new model mice of NASH. Seven-week-old male C57BL/6J mice were divided into the following groups: Control diet (control), CDAHFD (CDAHFD), CDAHFD supplemented with 0.05% (w/w) caffeine (caffeine), and CDAHFD supplemented with 0.1% (w/w) CGA (CGA). After seven weeks, the mice were killed and serum biochemical, histopathological, and molecular analyses were performed. Serum alanine aminotransferase (ALT) levels were significantly higher in the caffeine and CGA groups than in the CDAHFD group. On image analysis, the prevalence of Oil red O-positive areas (reflecting steatosis) was significantly higher in the caffeine group than in the CDAHFD group, and that of CD45R-positive areas (reflecting lymphocytic infiltration) in the hepatic lobule was significantly higher in the caffeine and CGA groups than in the CDAHFD group. Hepatic expression of interleukin (IL)-6 mRNA was higher in the caffeine and CGA groups than in the CDAHFD group, and the difference was statistically significant for the caffeine group. In conclusion, in the present study, caffeine and CGA significantly worsened the markers of liver cell injury, inflammation, and/or steatosis in NASH lesions in mice.

Oral Recombinant Methioninase Prevents Nonalcoholic Fatty Liver Disease in Mice on a High Fat Diet.

BACKGROUND/AIM: We have recently shown that oral recombinant methionase (o-rMETase) prevents obesity and diabetes onset in mice on a high-fat (HF) diet. The present study aimed to determine if o-rMETase can inhibit the onset of nonalcoholic fatty liver disease (NAFLD) onset in mice on a high-fat diet. MATERIALS AND METHODS: Male C57BL/6J mice in the control group were fed a normal-fat diet (NFD) (+6.5% fat), and other mice were fed a high-fat (HF) diet (+34.3% fat). Then, the mice on the HF diet were divided into two dietary groups: i) HF+phosphate buffered saline (PBS) group, and ii) HF+o-rMETase group. RESULT: The fatty change score in the livers of mice treated with HF+PBS increased to an average of 2.6 during the experimental period of 8 weeks. In contrast, the fatty change in the livers of mice on the HF+o-rMETase group had an average score of 0.92 (p=0.04, HF+PBS vs HF+o-rMETase). CONCLUSION: o-rMETase inhibited the onset of NAFLD as well as prevented obesity and the onset of diabetes on a high-fat diet, offering a possibility of a new paradigm to prevent liver cirrhosis or liver cancer via NAFLD.

Direct Factor X sequestration by systemic amyloid light-chain amyloidosis.

We present a lymphoplasmacytic lymphoma patient with Factor X (FX) deficiency. Despite the absence of FX inhibitor, the administration of fresh frozen plasma and anti-inhibitor coagulant complex did not increase the FX level. The autopsy showed that massive amyloid depositions to multiple organs and FX existed in union with amyloidosis.

[A Case of Transverse Colon Cancer with Liver Metastasis and Tumor Thrombosis of Portal Vein Effectively Treated with Chemotherapy].

The patient was a 70-year-old man. He was diagnosed with advanced transverse colon cancer. A computed tomography (CT)revealed liver metastasis and tumor thrombosis of portal vein. We started combination chemotherapy with capecita- bine/oxaliplatin(CapeOX). Perforation of the tumor was observed 5 days after CapeOX therapy was started. Treatment with abscess drainage and ileostmy, infection was controlled and general condition was improved. After 9 courses of CapeOX, we changed chemotherapy regimen to irinotecan/tegafur-gimeracil-oteracilpotassium (IRIS)due to strong side effects. In CT and FDG-PET examination after 8 courses of IRIS, the tumor of transverse colon, liver metastasis, and the tumor thrombosis of portalvein became unclear. A year and 6 months have passed since chemotherapy was started, recurrence was not observed. For the patients with unresectable colorectal cancer, it is necessary to consider multidisciplinary treatments including chemotherapy while considering the general condition of them.

Nivolumab-Induced Myocarditis Concomitant with Myasthenia Gravis.

We report a 69-year-old female patient with advanced lung cancer who developed myocarditis concomitant with myasthenia gravis (MG), also known as "Herzmyasthenie," after 3 cycles of nivolumab administration. Her initial symptoms were general malaise and double vision. However, her myocarditis deteriorated rapidly the following day, necessitating a temporary pacemaker and noninvasive positive pressure ventilation in the intensive care unit. Immunohistochemical examination of a myocardial biopsy suggested an immune response on the basis of HLA associations. The patient also developed impaired adduction of her left eye and elevated serum levels of acetylcholine receptor antibody, suggesting the onset of MG. Her condition gradually improved after immediate methylprednisolone pulse therapy. This case of nivolumab-induced "Herzmyasthenie" highlights the need to be aware that fulminant myocarditis might occur at the same time as MG during treatment with anti-programmed cell death-1 monoclonal antibodies.

Ras inhibitors display an anti-metastatic effect by downregulation of lysyl oxidase through inhibition of the Ras-PI3K-Akt-HIF-1α pathway.

Metastasis stands as the major obstacle for the survival from cancers. Nonetheless most existing anti-cancer drugs inhibit only cell proliferation, and discovery of agents having both anti-proliferative and anti-metastatic properties would be more beneficial. We previously reported the discovery of small-molecule Ras inhibitors, represented by Kobe0065, that displayed anti-proliferative activity on xenografts of human colorectal cancer (CRC) cell line SW480 carrying the K-rasG12Vgene. Here we show that treatment of cancer cells carrying the activated ras genes with Kobe0065 or a siRNA targeting Ras downregulates the expression of lysyl oxidase (LOX), which has been implicated in metastasis. LOX expression is enhanced by co-expression of RasG12V through activation of phosphatidylinositol 3-kinase (PI3K)/Akt and concomitant accumulation of hypoxia-inducible factor (HIF)-1α. Furthermore, Kobe0065 effectively inhibits not only migration and invasion of cancer cells carrying the activated ras genes but also lung metastasis of human CRC cell line SW620 carrying the K-rasG12V gene. Collectively, these results indicate that Kobe0065 prevents metastasis through inhibition of the Ras-PI3K-Akt-HIF-1α-LOX signaling and suggest that Ras inhibitors in general might exhibit both anti-proliferative and anti-metastatic properties toward cancer cells carrying the activated ras genes.

[Four Cases of Occult Breast Cancer Treated with Breast Conserving Therapy after Neoadjuvant Chemotherapy].

We report 4 patients with occult breast cancer(OBC)who underwent breast conserving therapy(BCT)after neoadjuvant chemotherapy(NAC). All patients complained of axillary tumor and were diagnosed by core needle biopsy. Pathological examination of the axillary lymph nodes proved that 3 cases were adenocarcinomas and 1 case was squamous cell carcinoma, but imaging studies could not depict any primary lesions in the breast and other organs. Since distant metastasis was not observed, BCT with axillary lymph node dissection(ALND)was performed after NAC. All patients were undergoing whole breast irradiation. There were no residual cancer cells in the axillary lymph nodes in case 1 due to the treatment effect of NAC, but lymph node metastasis remained in other 3 cases. In the second case, she followed a rapid outcome, and pulmonary metastasis appeared in 7 months after surgery and died in 10 months. In the other 3 cases, there has not been found local and distant recurrence. Although OBC requires appropriate systemic treatment, present observation indicated that ALND with breast irradiation after NAC could be a useful option.

Immunohistochemical study of hepatocyte, cholangiocyte and stem cell markers of hepatocellular carcinoma: the second report: relationship with tumor size and cell differentiation.

BACKGROUND: The purpose of this study is to investigate whether ordinary hepatocellular carcinomas (HCCs) show positivity of stem/progenitor cell markers and cholangiocyte markers during the process of tumor progression. METHODS: Ninety-four HCC lesions no larger than 8 cm from 94 patients were immuno-histochemically studied using two hepatocyte markers (Hep par 1 and α-fetoprotein), five cholangiocyte markers (cytokeratin CK7, CK19, Muc1, epithelial membrane antigen and carcinoembryonic antigen) and three hepatic stem/progenitor cell markers (CD56, c-Kit and EpCAM). The tumors were classified into three groups by tumor size: S1, < 2.0 cm; S2, 2.0-5.0 cm; S3, 5.0-8.0 cm. The tumors were also classified according to tumor differentiation: well, moderately and poorly differentiated. The relationship between the positive ratios of these markers, tumor size and tumor differentiation was examined. RESULTS: The positive ratios of cholangiocyte markers tended to be higher in larger sized and more poorly differentiated tumors (except for CK7). The positive ratios of stem/progenitor cell markers tended to be higher in larger sized and more poorly differentiated tumors (except for c-Kit). CONCLUSION: Ordinary HCC can acquire the characteristic of positivity of cholangiocyte and stem/progenitor cell markers during the process of tumor progression.

Current pharmacological therapies for nonalcoholic fatty liver disease/nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) is considered to be a hepatic manifestation of metabolic syndrome, and its incidence is rapidly increasing worldwide. It is currently the most common chronic liver disease. NASH can progress to liver cirrhosis and hepatocellular carcinoma, and may result in liver-related death. Currently, the principal treatment for NAFLD/NASH is lifestyle modification by diet and exercise. However, pharmacological therapy is indispensable because obese patients with NAFLD often have difficulty maintaining improved lifestyles. The pathogenesis of NAFLD/NASH has not been completely elucidated. However, insulin resistance, inflammatory cytokines, and oxidative stress are thought to be important in the development and/or progression of the disease. Currently, insulin sensitizers (thiazolidinediones) and antioxidants (vitamin E) seem to be the most promising therapeutic agents for NAFLD/NASH, and lipid-lowering drugs, pentoxifylline, angiotensin receptor blockers, and n-3 polyunsaturated fatty acids also have promise. However, there is a lack of consensus regarding the most effective and appropriate pharmacotherapy for NAFLD/NASH. Animal experiments suggest that herbal medicines and natural products may be promising therapeutic agents for NAFLD/NASH, but their efficacy and safety are yet to be investigated in human studies. In this paper, we review the existing and potential pharmacological therapies for NAFLD/NASH.

Preserved or enhanced OATP1B3 expression in hepatocellular adenoma subtypes with nuclear accumulation of ß-catenin.

AIM: Recent studies have indicated that hepatocellular adenoma (HCA) is a heterogenous group of benign tumors with various genetic and clinicopathological characteristics. We delineated the clinicopathological characteristics of HCA subtypes and evaluated the expression of transporter protein OATP1B3 in HCA. METHODS: HCA in 34 Japanese patients were investigated immunohistochemically and classified into four subtypes (HNF1α-inactivated type, H-HCA; ß-catenin-activated type, b-HCA; inflammatory type, I-HCA; unclassified type, u-HCA). Immunostaining of OATP1B3 protein in HCA tissue sections was performed to determine the association between OATP1B3 expression and HCA subtypes. RESULTS: HCA was categorized into the following four subtypes and two combined subtypes: 10 H-HCA (29%), 10 I-HCA (29%), seven b-HCA (21%), two b-HCA/H-HCA (6%), two b-HCA/I-HCA (6%) and three u-HCA (9%). The male-to-female ratio was 18:16. Oral contraceptive use was rare but seven HCA were found in patients with glycogen storage disease, congenital absence of the portal vein and idiopathic portal hypertension. OATP1B3 expression was decreased in 24 HCA but was preserved or increased in 10 HCA. All nine HCA with nuclear staining for ß-catenin showed preserved or enhanced OATP1B3 expression, indicating a significant association between nuclear ß-catenin accumulation and OATP1B3 expression in HCA. CONCLUSION: HCA subtype classification was validated in 91% of our Japanese subjects although their clinical backgrounds including rare contraceptive use were different from European subjects. A close association between preserved or enhanced OATP1B3 expression and b-HCA subtype indicated important modalities for clinical decisions in the treatment and follow up of patients with HCA.

Significance of downregulation of liver fatty acid-binding protein in hepatocellular carcinoma.

AIM: To investigate the significance of downregulation of liver fatty acid-binding protein (L-FABP) expression in hepatocellular carcinoma (HCC). METHODS: Tissue microarrays of 146 cases of HCC were used to perform immunohistochemical staining for L-FABP. For each L-FABP-negative HCC, further immunohistochemical staining was performed using a representative whole-tissue section to confirm the downregulation of L-FABP expression and to assess the intratumoral heterogeneity of the staining pattern. Clinical data were retrieved from the clinical files, and histological slides were reviewed. Immunohistochemical staining for cytokeratin (CK) 7, CK 19, ß-catenin, glutamine synthetase (GS), and serum amyloid A were also performed on the tissue microarrays. Clinicopathological features of the L-FABP-negative and L-FABP-positive HCC cases were compared. Furthermore, L-FABP and GS gene expression in HCC and cholangiocarcinoma cell lines were analyzed using real-time reverse transcription polymerase chain reaction. Mutation analysis of HNF1A [encoding hepatocyte nuclear factor 1 (HNF1)α] was performed for L-FABP-negative HCC cases. RESULTS: Sixteen (10.9%) of the 146 cases of HCC stained negative for L-FABP. When we examined the correlation between the downregulation pattern of L-FABP and tumor size, most cases of smaller HCC (≤ 2 cm in diameter) exhibited focal downregulation, while most cases of larger HCC (> 2 cm in diameter) exhibited diffuse downregulation. The correlation was statistically significant (P = 0.036). When the HCC was smaller, the L-FABP-negative area often corresponded to a "nodule-in-nodule" appearance. Among the small HCC cases, tumor differentiation was significantly lower, and the frequency of intratumoral inflammation was significantly lower in L-FABP-negative cases than in L-FABP-positive cases (P = 0.032 and P = 0.009, respectively). The frequency of positivity for ß-catenin and GS staining was significantly higher in L-FABP-negative cases of small HCC than in L-FABP-positive cases of small HCC (P = 0.009 and P = 0.000, respectively). Among six HCC cell lines examined, four showed higher expression of L-FABP, and the remaining two cell lines showed lower or no expression of L-FABP. Two of the 16 L-FABP-negative HCC cases possessed a mutation in exon 4 of HNF1A. CONCLUSION: In smaller HCC, L-FABP downregulation probably occurs because of phenotypic changes during tumor progression. Moreover, this downregulation correlated with tumor differentiation and intratumoral inflammation.

Histopathology of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD), a hepatic manifestation of metabolic syndrome, is the most common chronic liver disease, and the prevalence is rapidly increasing worldwide. Nonalcoholic steatohepatitis (NASH), the severe form of NAFLD, can progress to liver cirrhosis and hepatocellular carcinoma (HCC). Although noninvasive clinical scores and image-based diagnosis for NAFLD have improved, histopathological evaluation of biopsy specimens remains the gold standard for diagnosing NAFLD/NASH. Steatosis, lobular inflammation, and hepatocellular ballooning are all necessary components for the diagnosis of NASH; fibrosis is also typically observed. Other histopathological abnormalities commonly observed in NASH include hepatocellular glycogenated nuclei, lipogranulomas, and acidophil bodies. The characteristics of pediatric NAFLD/NASH differ from adult NAFLD/NASH. Specifically, steatosis and portal inflammation are more severe in pediatric NAFLD, while intralobular inflammation and perisinusoidal fibrosis are milder. Although interobserver agreement for evaluating the extent of steatosis and fibrosis is high, agreement is low for intralobular and portal inflammation. A recently reported histological variant of HCC, steatohepatitic HCC (SH-HCC), shows features that resemble non-neoplastic steatohepatitis, and is thought to be strongly associated with underlying NASH. In this report, we review the histopathological features of NAFLD/NASH.

High-dose methotrexate monotherapy followed by radiation for CD30-positive, anaplastic lymphoma kinase-1-positive anaplastic large-cell lymphoma in the brain of a child.

The authors report the case of an 11-year-old immunocompetent boy with primary CNS CD30-positive anaplastic large-cell lymphoma (ALCL) that was also positive for anaplastic lymphoma kinase-1. His initial clinical manifestation was acute meningitis of unknown etiology. Findings on CT scanning were normal. Although he received empirical treatment against infection, his systemic and neurological status deteriorated. Subsequent MRI revealed newly emerged enhanced lesions and concomitant edema in the left parietal lobe. Diagnosis was confirmed following a brain biopsy and immunohistochemical staining. Three courses of systemic high-dose methotrexate (HD-MTX) treatment with 2-week intervals was started, followed by whole-brain radiation. His clinical course improved, and he has remained disease-free for more than 8 years without any additional treatment. Because ALCL originating in the brain is extremely rare and difficult to diagnose, no standard treatment has been established. This report suggests that systemic HD-MTX monotherapy can be an effective and worthwhile tailored therapeutic option for pediatric primary CNS ALCL.

Stromal miR-21 is more important than miR-21 of tumour cells for the progression of gastric cancer.

BACKGROUND: Gastric cancer (GC) is a common cancer globally. miRNA-21 (miR-21) appears to be important in the tumourigenesis of almost all types of human cancer. However its precise localization in GC has yet to be clarified. We thus examined miR-21 localization in GC and revealed its clinicopathological importance. METHODS: Tissue arrays of 469 GCs from 454 patients were examined for miR-21 using in situ hybridization (ISH). The positivity was evaluated separately in tumour cells and stromal cells. Conventional sections of 10 GCs were also stained. Eight cases were examined by quantitative RT-PCR (qRT-PCR). RESULTS: miR-21 was highly expressed in tumour cells of 44% of cases and in cancer stroma of 51% of cases. miR-21 of tumour cells was not related to clinicopathological factors, whereas stromal miR-21 was related to many factors including tumour stage, size, and nodal metastasis. Stromal miR-21 gradually increased during tumour progression. ISH of whole sections showed stronger stromal positivity in invasive areas with desmoplastic reaction. Cancer stroma also showed higher miR-21 expression than tumour and non-tumourous tissue in the qRT-PCR study. CONCLUSION: Stromal miR-21 is closely related to tumour progression in GC. Stromal miR-21 of tumours might be a target of treatment.