Mieap forms membrane-less organelles involved in cardiolipin metabolism.

Biomolecular condensates (BCs) are formed by proteins with intrinsically disordered regions (IDRs) via liquid-liquid phase separation. Mieap/Spata18, a p53-inducible protein, participates in suppression of colorectal tumors by promoting mitochondrial quality control. However, the regulatory mechanism involved remains unclear. Here, we report that Mieap is an IDR-containing protein that drives formation of BCs involved in cardiolipin metabolism. Mieap BCs specifically phase separate the mitochondrial phospholipid, cardiolipin. Mieap directly binds to cardiolipin in vitro. Lipidomic analysis of cardiolipin suggests that Mieap promotes enzymatic reactions in cardiolipin biosynthesis and remodeling. Accordingly, four cardiolipin biosynthetic enzymes, TAMM41, PGS1, PTPMT1, and CRLS1 and two remodeling enzymes, PLA2G6 and TAZ, are phase-separated by Mieap BCs. Mieap-deficient cells exhibit altered crista structure, leading to decreased respiration activity and ATP production in mitochondria. These results suggest that Mieap may form membrane-less organelles to compartmentalize and facilitate cardiolipin metabolism, thus potentially contributing to mitochondrial quality control.

Analysis of RHOA mutations and their significance in the proliferation and transcriptome of digestive tract cancer cells.

The ras homolog family member A (RHOA) gene encodes a member of the Rho family of small GTPases and is known to function in reorganization of the actin cytoskeleton, which is associated with regulation of cell shape, attachment and motility. RHOA has been found to be recurrently mutated in gastrointestinal cancer; however, the functional significance of the mutated RHOA protein in digestive tract cancers remains to be uncovered. The aim of the present study was to understand the role of mutant RHOA in the proliferation and transcriptome of digestive tract cancer cells. Mutations of RHOA in one esophageal cancer cell line, OE19, eight gastric cancer cell lines, namely, AGS, GCIY, HGC-27, KATO III, MKN1, MKN45, SNU16 and SNU719, as well as two colon cancer cell lines, CCK-81 and SW948, were determined using Sanger sequencing. The results uncovered several mutations, including p.Arg5Gln and p.Tyr42Cys in CCK-81, p.Arg5Trp and p.Phe39Leu in SNU16, p.Gly17Glu in SW948, p.Tyr42Ser in OE19, p.Ala61Val in SNU719, p.Glu64del in AGS. Wild-type RHOA was identified in GCIY, HGC-27, KATO III, MKN1 and MKN45. Knockdown of RHOA using small interfering RNA attenuated the in vitro proliferation in the three-dimensional culture systems of GCIY, MKN1, OE19 and SW948, whereas no apparent changes were seen in CCK-81, HGC-27 and SNU719. Transcriptome analysis revealed that downregulation of the long non-coding RNA (lnc)-DERA-1 was observed in all tested cell lines following RHOA knockdown in the RHOA-mutated cell lines. Gene Ontology analysis showed that the genes associated with small molecule metabolic process, oxidation-reduction processes, protein kinase activity, transport, and cell junction were commonly downregulated in cells whose proliferation was attenuated by the knockdown of RHOA. These results suggested that certain RHOA mutations may result in upregulation of lnc-DERA-1 and genes associated with cellular metabolism and proliferation in digestive tract cancers.

Development of a system combining comprehensive genotyping and organoid cultures for identifying and testing genotype-oriented personalised medicine for pancreatobiliary cancers.

BACKGROUND: Pancreatobiliary cancer is a highly aggressive tumour with a dismal prognosis. Personalised medicine represents a promising and effective therapeutic approach for this intractable disease. In this study, we aimed to establish a system for identifying and testing genotype-oriented targeted drugs for pancreatobiliary cancers by combining exome sequencing and organoid culture of primary tumours. METHODS: Tumour cells isolated from resected tumours were subjected to organoid cultures based on published protocols with modifications. Exome sequencing was performed on the primary tumours. Histopathological and molecular features of the primary tumours were validated in the corresponding organoids. Genotype-oriented candidate targeted drugs were identified from exome sequencing, and their efficacies were tested in the organoids. RESULTS: Organoid cultures succeeded in 30 of 54 (55.6%) cases. Six primary cancers of the biliary tract and gall bladder were subjected to exome sequencing, which revealed a variety of somatic mutations of genes involved in signalling pathways, epigenetic modifiers, genome maintenance and metabolic enzymes. Most of the organoids of these 6 cases showed identical histopathological features and genomic aberrations as those of the primary tumours. Some of the aberrations were candidates for targeted therapies. Integrin-linked kinase (ILK) was one such candidate target, and an ILK inhibitor was confirmed to suppress proliferation of patient-derived organoids. CONCLUSIONS: By combining exome sequencing and organoid culture, our model enabled to identify genotype-oriented targets for personalised medicine and to test efficacies of candidate targeted drugs in the organoids. The current proof-of-concept approach could increase therapeutic opportunities for patients with pancreatobiliary cancers.

Staging of gastric cancer with the Clinical Stage Prediction score.

BACKGROUND: Chemotherapy with or without surgery is the first-line treatment for stage III/IV gastric cancer, while surgery is the first-line treatment for stage I/II gastric cancer. Accordingly, it is important to distinguish between stage III/IV and stage I/II gastric cancer, but clinical staging is less accurate than pathological staging. This study was performed to develop a clinical score that could distinguish stage III/IV gastric cancer from stage I/II gastric cancer. METHODS: We reviewed 2722 patients who underwent gastrectomy at our hospital from January 1996 to December 2015. As pretreatment factors potentially related to tumor stage, we assessed age, sex, tumor markers, tumor diameter, tumor location, tumor histology, and macroscopic type. Factors showing significance on multivariate analysis were used to develop the Clinical Stage Prediction score (CSP score), and a cutoff value for the score was determined by receiver operating characteristics analysis. RESULTS: According to multivariate analysis, clinical factors associated with stage III/IV disease were elevation of the carcinoembryonic antigen level, tumor diameter ≥ 60 mm, circumferential gastric involvement, esophageal infiltration, mucinous adenocarcinoma, and macroscopic types 2-4. The CSP score was obtained by weighting these factors according to the non-standardized ß-coefficient. Receiver operating characteristics analysis indicated that the optimum cutoff value of the CSP score was 17 points. Among 1042 patients with a CSP score ≥ 17 points, 820 patients (78.7%) had stage III/IV gastric cancer. Conversely, among 1680 patients with a CSP score < 17 points, 1547 patients (92.1%) had stage I/II gastric cancer. When discrimination of stage III/IV gastric cancer from stage I/II gastric cancer by the CSP score was assessed, the sensitivity was 78.7%, specificity was 92.1%, positive predictive value was 86.0%, and negative predictive value was 87.5%. CONCLUSIONS: The CSP score can be helpful for differentiating stage III/IV gastric cancer from stage I/II gastric cancer based on pretreatment clinical factors.

Near-Comprehensive Resequencing of Cancer-Associated Genes in Surgically Resected Metastatic Liver Tumors of Gastric Cancer.

Liver metastasis is a major cause of death in patients with gastric cancer. The molecular alterations in clinically resected liver metastases of gastric cancer were evaluated to identify candidate biomarkers and therapeutic targets. Seventy-four patients, including 37 with liver metastasis who underwent gastrectomy and hepatectomy for gastric cancer and 37 without liver metastasis who underwent gastrectomy for gastric cancer, were studied. Next-generation resequencing was performed for 412 cancer-associated genes in metastatic and/or primary tumors from 30 patients and somatic mutations in TP53, LRP1B, PIK3CA, ADAMTS20, PAX7, FN1, FOXO3, WRN, PTEN, ETV4, and RNF213 were found in metastatic tumors. TP53 mutations were studied by Sanger sequencing in the remaining patients; the number of patients with TP53 mutations in metastatic tumors was significantly higher among those with liver metastasis (86.5%, 32/37) versus those without liver metastasis (40.5%; 15/37; P < 0.0001). TP53 mutations in metastatic liver tumors and corresponding primary tumors were identical in 96.9% (31/32), including some patients with heterogeneous primary tumor components. Immunohistochemical analyses showed aberrant p53 expression in tumors with TP53 mutations. In silico functional evaluations indicated functional loss of missense-mutated TP53. Thus, the p53 pathway may facilitate the development of biomarkers and therapeutic approaches to treat gastric cancer metastases to the liver.

Mutations in BRCA1, BRCA2, and PALB2, and a panel of 50 cancer-associated genes in pancreatic ductal adenocarcinoma.

Mutations in genes of the breast cancer susceptibility gene (BRCA) pathway, namely, BRCA1, BRCA2, and PALB2, can provide useful information for the efficacy of platinum-based or poly ADP-ribose polymerase inhibitors chemotherapeutic regimens. Pancreatic ductal adenocarcinoma (PDAC) is an important target for such precision chemotherapies because of its dismal prognosis. We analyzed mutations in the entire coding regions of the BRCA pathway genes, expression of breast cancer 2 (BRCA2), and mutations in hotspots of 50 cancer-associated genes in 42 surgically resected PDACs, and evaluated their associations with clinicopathological features. We identified 13 rare germline mutations in the BRCA pathway genes; 68 somatic mutations in KRAS, TP53, SMAD4, CDKN2A, GNAS, SMARCB1, and RB1; and 2 germline variations in MLH1. Among them, BRCA2S2148fs was known to be pathogenic. BRCA2R18H and BRCA2G2044V were enriched in tumor tissues. BRCA2K799R and BRCA2R2964T were novel germline variations. Patients harboring potentially deleterious mutations in the BRCA pathway genes showed significantly better prognosis than those with benign mutations or no mutation. These results indicate that rare germline variations in BRCA pathway genes could be found more frequently than previously anticipated and, more importantly, potentially deleterious mutations of them could be a favorable prognostic factor in patients with resectable PDACs.

Somatic mutations and increased lymphangiogenesis observed in a rare case of intramucosal gastric carcinoma with lymph node metastasis.

BACKGROUND AND AIM: Intramucosal gastric adenocarcinoma of the well-moderately differentiated type only exhibits lymph node metastasis in extremely rare cases. We encountered such case and investigated both the lymphangiogenic properties and somatic mutations in the cancer to understand the prometastatic features of early-stage gastric cancer. METHODS: We quantitatively measured the density of lymphatic vessels and identified mutations in 412 cancer-associated genes through next-generation target resequencing of DNA extracted from tumor cells in a formalin-fixed and paraffin-embedded tissue. Functional consequence of the identified mutation was examined in vitro by means of gene transfection, immunoblot, and the quantitative real-time polymerase chain reaction assay. RESULTS: The intramucosal carcinoma was accompanied by abundant lymphatic vessels. The metastatic tumor harbored somatic mutations in NBN, p.P6S, and PAX8, p.R49H. The PAX8R49H showed significantly higher transactivation activity toward E2F1 than the wild-type PAX8 (P< 0.001). CONCLUSIONS: Our data suggest that increased lymphangiogenesis and somatic mutations of NBN and/or PAX8 could facilitate lymph node metastasis from an intramucosal gastric carcinoma. These findings may potentially inform evaluations of the risk of developing lymph node metastasis in patients with intramucosal gastric cancer.

Pancreatic intraductal tubulopapillary neoplasm is genetically distinct from intraductal papillary mucinous neoplasm and ductal adenocarcinoma.

Intraductal tubulopapillary neoplasm is a relatively recently described member of the pancreatic intraductal neoplasm family. The more common member of this family, intraductal papillary mucinous neoplasm, often carries genetic alterations typical of pancreatic infiltrating ductal adenocarcinoma (KRAS, TP53, and CDKN2A) but additionally has mutations in GNAS and RNF43 genes. However, the genetic characteristics of intraductal tubulopapillary neoplasm have not been well characterized. Twenty-two intraductal tubulopapillary neoplasms were analyzed by either targeted next-generation sequencing, which enabled the identification of sequence mutations, copy number alterations, and selected structural rearrangements involving all targeted (≥300) genes, or whole-exome sequencing. Three of these intraductal tubulopapillary neoplasms were also subjected to whole-genome sequencing. All intraductal tubulopapillary neoplasms revealed the characteristic histologic (cellular intraductal nodules of back-to-back tubular glands lined by predominantly cuboidal cells with atypical nuclei and no obvious intracellular mucin) and immunohistochemical (immunolabeled with MUC1 and MUC6 but were negative for MUC2 and MUC5AC) features. By genomic analyses, there was loss of CDKN2A in 5/20 (25%) of these cases. However, the majority of the previously reported intraductal papillary mucinous neoplasm-related alterations were absent. Moreover, in contrast to most ductal neoplasms of the pancreas, MAP-kinase pathway was not involved. In fact, 2/22 (9%) of intraductal tubulopapillary neoplasms did not reveal any mutations in the tested genes. However, certain chromatin remodeling genes (MLL1, MLL2, MLL3, BAP1, PBRM1, EED, and ATRX) were found to be mutated in 7/22 (32%) of intraductal tubulopapillary neoplasms and 27% harbored phosphatidylinositol 3-kinase (PI3K) pathway (PIK3CA, PIK3CB, INPP4A, and PTEN) mutations. In addition, 4/18 (18%) of intraductal tubulopapillary neoplasms had FGFR2 fusions (FGFR2-CEP55, FGFR2-SASS6, DISP1-FGFR2, FGFR2-TXLNA, and FGFR2-VCL) and 1/18 (5.5%) had STRN-ALK fusion. Intraductal tubulopapillary neoplasm is a distinct clinicopathologic entity in the pancreas. Although its intraductal nature and some clinicopathologic features resemble those of intraductal papillary mucinous neoplasm, our results suggest that intraductal tubulopapillary neoplasm has distinguishing genetic characteristics. Some of these mutated genes are potentially targetable. Future functional studies will be needed to determine the consequences of these gene alterations.

Constant maintenance of an alternative route of coronary flow in radical surgery for gastric cancer following coronary artery bypass grafting involving the right gastroepiploic artery: a case report.

We describe a 64-year-old man diagnosed as having gastric cancer with a patent right gastroepiploic artery (RGEA) used for coronary artery bypass grafting (CABG). Before gastrectomy, the native coronary artery was revascularized to safely dissect the infrapyloric lymphatic tissue along the layer recently identified as an appropriate layer for radical lymphadenectomy, in anticipation of preserving the radically skeletonized RGEA. The perioperative strategy was feasible. Postoperatively, hemorrhage extended the stopping period of antiplatelet therapy. However, since the RGEA was preserved, an alternative route was available for coronary flow. After a 41-month postoperative follow-up, the patient remained in good health, with no recurrence or cardiac ischemia. In this case, the alternative route of coronary flow could be constantly maintained, although radical infrapyloric lymphadenectomy had been performed. Preoperative revascularization and preserving the RGEA with radical skeletonization can be a safe yet permissibly radical strategy for gastric cancer treatment following CABG involving the RGEA.

A primary tumor of mixed histological type is a novel poor prognostic factor for patients undergoing resection of liver metastasis from gastric cancer.

BACKGROUND: Surgical resection can be an option for the treatment of metastatic liver tumors originating from gastric cancer; however, its prognostic impact is controversial. The aim of this study was to identify prognostic factors in patients with surgical resection of liver metastasis from gastric cancer. METHODS: We retrospectively analyzed the clinicopathological features of 38 consecutive patients undergoing hepatectomy for metastatic tumors from gastric cancer in our institution between 1990 and 2014. RESULTS: The median overall survival of the patients was 28 months. The 5-year survival rate was 33.9%. Primary tumors of a mixed histological type, and residual tumors during the course of treatment were identified as significant independent poor prognostic factors. CONCLUSIONS: Histological evaluation of primary tumors may aid to identify patients suitable for undergoing surgical resection of liver metastasis from gastric cancer.

[Pancreatic and gastric metastases occurring a decade after nephrectomy for renal cell carcinoma].

We report the case of a 64-year-old man who underwent resection on two occasions for recurrent renal cell carcinoma. He first underwent right nephrectomy for renal cell carcinoma, and 10 years later, he underwent pylorus-preserving pancreaticoduodenectomy for pancreatic metastasis. Microscopic extracapsular invasion without lymph node metastasis was observed at that time. Twelve years after the first surgery, he was diagnosed with stomach metastasis. Clinically, metastases to other organs was not observed, and endoscopic ultrasonography revealed no changes in the submucosal layer; endoscopic submucosal dissection was subsequently performed. Pathologically, the tumor was found to be localized in the mucosal layer. There has been no occurrence of metastases for 2 years and 6 months since the last surgery.

HER2-positive gastric cancer with paraaortic nodal metastasis successfully resected after chemotherapy with trastuzumab: a case report.

We report on a case of human epidermal growth factor receptor-2 (HER2)-positive gastric cancer with paraaortic lymph node metastasis. The patient (a 49-year-old female) received chemotherapy (capecitabine and cisplatin) plus molecular-targeted therapy (trastuzumab), followed by curative resection. Interestingly, the resected residual cancer was HER2-negative. Intra-tumor heterogeneity hinders molecular-targeted therapy for gastric cancer. In our case, continued trastuzumab administration presented few benefits since the residual cancer cells were HER2-negative. No consensus exists regarding the appropriate therapy for unresectable gastric cancers whose non-curative factors disappear following trastuzumab chemotherapy. The principal options are treatment with surgery or continued chemotherapy with trastuzumab. In our case, resection treated the HER2-negative residual cancer effectively, resulting in curative therapy. This is the first case of positive-to-negative change in the HER2 expression of residual tumor cells following trastuzumab therapy. It suggests that, due to intra-tumor heterogeneity, the risks presented by remnant HER2-negative cancer cells persist despite trastuzumab therapy.