Clinicopathological and genetic differences between low-grade and high-grade colorectal mucinous adenocarcinomas.

BACKGROUND: Although colorectal mucinous adenocarcinomas (MCs) are conventionally regarded as exhibiting high-grade differentiation, they can be divided by differentiation into 2 groups according to the glandular appearance: low-grade mucinous adenocarcinoma (low-MC) and high-grade mucinous adenocarcinoma (high-MC). METHODS: Patients with colorectal cancer (CRC) who underwent surgical resection between 2000 and 2012 were enrolled in this study. Among the cases with MC, the clinicopathological and genetic differences between low-MC and high-MC were investigated with next-generation sequencing. RESULTS: A total of 1373 patients with CRC were analyzed. Forty patients (2.9%) had MC, and 13 patients had high-MC. Patients with MC had significantly shorter disease-free survival (DFS) and overall survival (OS) periods than those with nonmucinous carcinoma. When low-MC patients and high-MC patients were compared, those with high-MC had significantly shorter DFS and OS periods than those with low-MC. Multivariate analyses revealed that high-MC was significantly associated with both shorter DFS and shorter OS, but low-MC was not. A genome analysis revealed that low-MC had a considerably larger number of mutations than high-MC, and Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations and adenomatous polyposis coli mutations were particularly frequently found in low-MC. In contrast, SMAD family member 4 (SMAD4) mutations were frequently found in high-MC. CONCLUSIONS: High-MC is an independent prognostic factor in CRC (but low-MC is not), and it is genetically different from other CRCs, including low-MC. Both the clinicopathological differences and the genetic differences suggest that low-MC and high-MC should be distinguished in clinical settings.

Inter- and intra-tumor profiling of multi-regional colon cancer and metastasis.

Intra- and inter-tumor heterogeneity may hinder personalized molecular-target treatment that depends on the somatic mutation profiles. We performed mutation profiling of formalin-fixed paraffin embedded tumors of multi-regional colon cancer and characterized the consequences of intra- and inter-tumor heterogeneity and metastasis using targeted re-sequencing. We performed targeted re-sequencing on multiple spatially separated samples obtained from multi-regional primary colon carcinoma and associated metastatic sites in two patients using next-generation sequencing. In Patient 1 with four primary tumors (P1-1, P1-2, P1-3, and P1-4) and one liver metastasis (H1), mutually exclusive pattern of mutations was observed in four primary tumors. Mutations in primary tumors were identified in three regions; KARS (G13D) and APC (R876*) in P1-2, TP53 (A161S) in P1-3, and KRAS (G12D), PIK3CA (Q546R), and ERBB4 (T272A) in P1-4. Similar combinatorial mutations were observed between P1-4 and H1. The ERBB4 (T272A) mutation observed in P1-4, however, disappeared in H1. In Patient 2 with two primary tumors (P2-1 and P2-2) and one liver metastasis (H2), mutually exclusive pattern of mutations were observed in two primary tumors. We identified mutations; KRAS (G12V), SMAD4 (N129K, R445*, and G508D), TP53 (R175H), and FGFR3 (R805W) in P2-1, and NRAS (Q61K) and FBXW7 (R425C) in P2-2. Similar combinatorial mutations were observed between P2-1 and H2. The SMAD4 (N129K and G508D) mutations observed in P2-1, however, were nor detected in H2. These results suggested that different clones existed in primary tumors and metastatic tumor in Patient 1 and 2 likely originated from P1-4 and P2-1, respectively. In conclusion, we detected the muti-clonalities between intra- and inter-tumors based on mutational profiling in multi-regional colon cancer using next-generation sequencing. Primary region from which metastasis originated could be speculated by mutation profile. Characterization of inter- and inter-tumor heterogeneity can lead to underestimation of the tumor genomics landscape and treatment strategy of personal medicine.

[Clinical trial of a seven-peptide vaccine and tegafur-uracil/leucovorin as combination therapy for advanced colorectal cancer].

We conducted a clinical trial of a seven-peptide vaccine in combination with tegafur-uracil/Leucovorin for advanced colorectal cancer. These antigenic peptides were derived from 5 proteins identified as cancer-testis antigens(ring finger protein 43 [RNF43], translocase of outer mitochondrial membrane 34[TOMM34], maternal embryonic leucine zipper kinase[MELK], forkhead box M1[FOXM1], and holliday junction recognition protein[HJURP])and 2 vascular endothelial growth factor receptors(VEGFR1 and VEGFR2). Thirty patients with advanced colorectal cancer were enrolled. We found that 25 patients had Grade 1 injection-site redness/induration and 1 patient had Grade 3 anaphylaxis. Tumor imaging revealed that 3 patients had a partial response (PR), 15 had stable disease(SD)and 12 had progressive disease(PD). This trial showed that treatment with the seven-peptide vaccine and UFT/LV was well tolerated and feasible for advanced colorectal cancer.

[Treatment outcome of peptide vaccination for advanced colorectal cancer].

Complementary DNA( cDNA) microarray technology coupled with laser microdissection has been used to identify human leukocyte antigen (HLA)-A24-restricted epitope peptides as potential targets for cancer vaccination in colorectal cancer patients. These antigenic peptides were derived from 2 different cancer-testis antigens, ring finger protein 43 (RNF43) and translocase of outer mitochondrial membrane 34( TOMM34). We conducted a clinical trial of colorectal cancer-specific peptide( RNF43, TOMM34) vaccines with uracil/tegafur( UFT)+Leucovorin( LV) for the treatment of advanced or recurrent colorectal cancer. The vaccinations were well tolerated without any serious adverse events. There were long-term survivors in the group showing cytotoxic T lymphocyte (CTL) responses against both RNF43 and TOMM34, as well as in the group showing CTL responses against either RNF43 or TOMM34. A new study has been planned to obtain more immunological responses. We started a clinical trial of vaccines against multiple peptides (RNF43, TOMM34, forkhead box protein M1 [FOXM1], maternal embryonic leucine zipper kinase [MELK], holliday junction recognition protein[HJURP], vascular endothelial growth factor receptor 1[VEGFR1], and VEGFR2) for the treatment of advanced or recurrent colorectal cancer.

Liver Abscess due to Streptococcus intermedius Bacteremia and Its Association with Colonic Carcinoma: Is Bacteremia with Streptococcus intermedius an Alert for Colonic Carcinoma?

Liver abscess caused by some kinds of Streptococcus group such as Streptococcus bovis group has been recognized to associate with colorectal cancer. Streptococcus milleri group with liver abscess has not been received much attention in this point of view. Here, we report the case of a 63-year-old man who developed liver abscess with S. intermedius, which belongs to the S. milleri group. We confirmed that this case was accompanied by cecal carcinoma by colonoscopy. The tumor was a pathological lead point of intussusception of cecum. On the 26th day, open right hemicolectomy was performed. In this case, bacterial endophthalmitis was a complication due to bacteremia. The patient underwent ophthalmic surgery on the 98th day. Research investigating 16S rRNA of the mucosal colon microbiome reported that the S. intermedius gene was upregulated in patients with colorectal carcinoma. It is recommended that liver abscess with S. intermedius bacteremia should alert the clinician about the risks of carcinoma of the colon and abscess formation in distant organs. We here list the case reports of liver abscess caused by Streptococcus other than S. bovis group, which was associated with colonic carcinoma, and suggest the need for further research about S. milleri group.

Activin signal promotes cancer progression and is involved in cachexia in a subset of pancreatic cancer.

We previously reported that activin produces a signal with a tumor suppressive role in pancreatic cancer (PC). Here, the association between plasma activin A and survival in patients with advanced PC was investigated. Contrary to our expectations, however, patients with high plasma activin A levels had a significantly shorter survival period than those with low levels (median survival, 314 days vs. 482 days, P = 0.034). The cellular growth of the MIA PaCa-2 cell line was greatly enhanced by activin A via non-SMAD pathways. The cellular growth and colony formation of an INHBA (beta subunit of inhibin)-overexpressed cell line were also enhanced. In a xenograft study, INHBA-overexpressed cells tended to result in a larger tumor volume, compared with a control. The bodyweights of mice inoculated with INHBA-overexpressed cells decreased dramatically, and these mice all died at an early stage, suggesting the occurrence of activin-induced cachexia. Our findings indicated that the activin signal can promote cancer progression in a subset of PC and might be involved in cachexia. The activin signal might be a novel target for the treatment of PC.

Activated MET acts as a salvage signal after treatment with alectinib, a selective ALK inhibitor, in ALK-positive non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) carrying echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) rearrangements is hypersensitive to ALK inhibitors, including crizotinib and alectinib. Crizotinib was initially designed as a MET inhibitor, whereas alectinib is a selective ALK inhibitor. The MET signal, which is inhibited by crizotinib but not by alectinib, is dysregulated in many human cancers. However, the role of the MET signal in ALK-positive NSCLC remains unclear. In this study, we found that hepatocyte growth factor (HGF), ligand of MET, mediated the resistance to alectinib, but not to crizotinib, via the MET signal in ALK-positive NSCLC cell lines (H3122 and H2228 cell lines). In addition, alectinib activated the MET signal even in the absence of HGF and the inhibition of the MET signal enhanced the efficacy of alectinib. These findings suggest that activated MET acts as a salvage signal in ALK-positive NSCLC. This novel role of the MET signal in ALK-positive NSCLC may pave the way for further clinical trials examining MET inhibitors.

Hypoxia induces resistance to ALK inhibitors in the H3122 non-small cell lung cancer cell line with an ALK rearrangement via epithelial-mesenchymal transition.

Patients with non-small cell lung cancer (NSCLC) with echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase (ALK) rearrangements generally respond to ALK inhibitors such as crizotinib. However, some patients with EML4-ALK rearrangements respond poorly to crizotinib. Hypoxia is involved in the resistance to chemotherapeutic treatments in several cancers, and we investigated the association between the responses to ALK inhibitors and hypoxia. Sensitivity of the H3122 NSCLC cell line (EML4-ALK rearrangement) to ALK inhibitors (crizotinib or alectinib) was investigated during a normoxic or hypoxic state using an MTT assay. We found that the cell line was resistant to the inhibitors during hypoxia. Hypoxia mediated morphologic changes, including cell scattering and the elongation of the cell shape, that are characteristic of the epithelial-mesenchymal transition (EMT). A migration assay demonstrated that the number of migrating cells increased significantly during hypoxia, compared with during normoxia. Regarding EMT-related molecules, the expressions of slug, vimentin, and fibronectin were increased while that of E-cadherin was decreased by hypoxia. In addition, hypoxia inducible factor 1A-knockdown cancelled the hypoxia-induced EMT and resistance. Our findings indicate that hypoxia induces resistance to ALK inhibitors in NSCLC with an EML4-ALK rearrangement via the EMT.

MEK inhibitor for gastric cancer with MEK1 gene mutations.

The prognosis for patients with unresectable advanced or recurrent gastric cancer remains poor. The identification of additional oncogenes with influences similar to those of epidermal growth factor receptor gene mutations, upon which the growth of cancer cells is dependent, is needed. In this study, we evaluated sensitivity to MEK inhibitors (GSK1120212 and PD0325901) in several gastric cancer cell lines in vitro and found three poorly differentiated gastric cancer cell lines that were hypersensitive to the inhibitors. The sequence analyses in these three cell lines revealed that one cell line had a novel MEK1 mutation, while the other two had previously reported KRAS and MEK1 mutations, respectively; the gene statuses of the other resistant cell lines were all wild-type. Experiments using MEK1 expression vectors demonstrated that the MEK1 mutations induced the phosphorylation of ERK1/2 and had a transforming potential, enhancing the tumorigenicity. The MEK inhibitor dramatically reduced the phosphorylation of ERK1/2 and induced apoptosis in the cell lines with MEK1 mutations. In vivo, tumor growth was also dramatically decreased by an inhibitor. One of the 46 gastric cancer clinical samples that were examined had a MEK1 mutation; this tumor had a poorly differentiated histology. Considering the addiction of cancer cells to active MEK1 mutations for proliferation, gastric cancer with such oncogenic MEK1 mutations might be suitable for targeted therapy with MEK inhibitors.