Koh Miura

Inhibitor of apoptosis protein family as diagnostic markers and therapeutic targets of colorectal cancer

The apoptosis and antiapoptotic signaling pathways are important for regulating carcinogenesis and cancer progression, and for determining prognosis. Molecules involved in apoptosis represent potential cancer diagnostic markers and therapeutic targets. The inhibitor of apoptosis protein (IAP) family includes several important molecules involved in apoptosis that might represent such targets. Increasing evidence has demonstrated that the IAP family of proteins is integral for antiapoptotic and nuclear factor-κB signal transduction, and enhanced expression of IAPs contributes to colon carcinogenesis and its poor prognosis, as well as to drug resistance of tumors. X-linked IAP, cIAP1, cIAP2, and survivin are prognostic markers of colorectal cancer, and survivin and cIAP2 are also utilized to predict the effect of anticancer treatment in colorectal cancer patients. Novel therapies such as YM155 and LY2181308 targeting survivin, AEG35156 and phenoxodiol targeting X-linked IAP, AT-406 as a Smac mimetic, and survivin peptides are currently being evaluated in clinical trials. This report reviews the involvement of the IAP family in colorectal adenocarcinoma in order to summarize the role of the IAP family members as diagnostic and therapeutic targets, and to provide an overview of the future course of research in this area.

Down‐regulation of cIAP2 enhances 5‐FU sensitivity through the apoptotic pathway in human colon cancer cells

Currently 5‐fluorouracil (5‐FU) plays a central role in the chemotherapeutic regimens for colorectal cancers and thus it is important to understand the mechanisms that determine 5‐FU sensitivity. The expression profiles of human colon cancer cell line DLD‐1, its 5‐FU‐resistant subclone DLD‐1/FU and a futher 21 types of colon cancer cell lines were compared to identify the novel genes defining the sensitivity to 5‐FU and to estimate which population of genes is responsible for 5‐FU sensitivity. In the hierarchical clustering, DLD‐1 and DLD‐1/FU were most closely clustered despite over 100 times difference in their 50% inhibitory concentration of 5‐FU. In DLD‐1/FU, the population of genes differentially expressed compared to DLD‐1 was limited to 3.3%, although it ranged from 4.8% to 24.0% in the other 21 cell lines, thus indicating that the difference of 5‐FU sensitivity was defined by a limited number of genes. Next, the role of the cellular inhibitor of apoptosis 2 (cIAP2) gene, which was up‐regulated in DLD‐1/FU, was investigated for 5‐FU resistance using RNA interference. The down‐regulation of cIAP2 efficiently enhanced 5‐FU sensitivity, the activation of caspase 3/7 and apoptosis under exposure to 5‐FU. The immunohistochemistry of cIAP2 in cancer and corresponding normal tissues from colorectal cancer patients in stage III revealed that cIAP2 was more frequently expressed in cancer tissues than in normal tissues, and cIAP2‐positive patients had a trend toward early recurrence after fluorouracil‐based chemotherapy. Although the association between drug sensitivity and the IAP family in colorectal cancer has not yet been discussed, cIAP2 may therefore play an important role as a target therapy in colorectal cancer. (Cancer Sci 2009; 100: 903–913)

Identification of a new adhesin-like protein from Lactobacillus mucosae ME-340 with specific affinity to the human blood group A and B antigens.

Aims:  To identify and characterize a new adhesin‐like protein of probiotics that show specific adhesion to human blood group A and B antigens.

cIAP2 as a therapeutic target in colorectal cancer and other malignancies

Colorectal cancer is one of the most common malignancies worldwide and 70% of tumors are resectable, but patients with metastatic diseases cannot be cured with current treatment modalities. Inhibition of the apoptotic pathway is one of the factors that may be responsible for carcinogenesis and drug resistance, and the inhibitor of apoptosis protein (IAP) family is thought to prevent apoptosis through inhibition of direct caspases and pro-caspases. Recently an increasing amount of evidence has been accumulated regarding cIAP2 and other IAP proteins of the antiapoptotic pathway and NF-κB signal transduction. IAPs are abnormally regulated and expressed in the majority of human malignancies at elevated levels. As a result, they have recently been reported to be therapeutic targets. The downregulation of cIAP2 efficiently enhances apoptosis through the activation of caspase 3/7 and 5-fluorouracil (5-FU) sensitivity in colorectal cancer cells exposed to 5-FU. This report reviews the evidence for cIAP2 and other IAP molecules as a therapeutic target for malignancies including colorectal cancer. So far, the information on colorectal cancer is limited; so this study includes other malignancies as well, in order to summarize the current knowledge of drug development targeting IAP molecules and provide an overview of the future course.

5-FU Metabolism in Cancer and Orally-Administrable 5-FU Drugs

5-Fluorouracil (5-FU) is a key anticancer drug that for its broad antitumor activity, as well as for its synergism with other anticancer drugs, has been used to treat various types of malignancies. In chemotherapeutic regimens, 5-FU has been combined with oxaliplatin, irinotecan and other drugs as a continuous intravenous infusion. Recent clinical chemotherapy studies have shown that several of the regimens with oral 5-FU drugs are not inferior compared to those involving continuous 5-FU infusion chemotherapy, and it is probable that in some regimens continuous 5-FU infusion can be replaced by oral 5-FU drugs. Historically, both the pharmaceutical industry and academia in Japan have been involved in the development of oral 5-FU drugs, and this review will focus on the current knowledge of 5-FU anabolism and catabolism, and the available information about the various orally-administrable 5-FU drugs, including UFT, S-1 and capecitabine. Clinical studies comparing the efficacy and adverse events of S-1 and capecitabine have been reported, and the accumulated results should be utilized to optimize the treatment of cancer patients. On the other hand, it is essential to elucidate the pharmacokinetic mechanism of each of the newly-developed drugs, to correctly select the drugs for each patient in the clinical setting, and to further develop optimized drug derivatives.

siRNA-mediated knockdown against CDCA1 and KNTC2, both frequently overexpressed in colorectal and gastric cancers, suppresses cell proliferation and induces apoptosis

Ndc80 has been shown to play an important role in stable microtubule-kinetochore attachment, chromosome alignment, and spindle checkpoint activation in mitosis. It is composed of two heterodimers, CDCA1-KNTC2 and SPC24-SPC25. Overexpression of CDCA1 and KNTC2 is reported to be associated with poor prognosis in non-small cell lung cancers (NSCLC), and siRNA-mediated knockdown against CDCA1 or KNTC2 has been found to inhibit cell proliferation and induction of apoptosis in NSCLC, ovarian cancer, cervical cancer and glioma. Therefore, CDCA1 and KNTC2 can be considered good candidates for molecular target therapy as well as diagnosis in some cancers. However, the role of the Ndc80 complex in colorectal and gastric cancers (CRC and GC) still remains unclear. In the present study, we used qRT-PCR to evaluate the expression levels of CDCA1, KNTC2, SPC24 and SPC25 in CRC and GC and employed siRNA-mediated knockdown to examine cell proliferation and apoptosis. mRNA overexpression of these four genes was observed in CRCs and GCs when compared with the corresponding normal mucosae. Additionally, the expression levels of tumor/normal ratios of CDCA1, KNTC2, SPC24 and SPC25 correlated with each other in CRCs. MTT assays revealed that cell growths after the siRNA-mediated knockdown of either CDCA1 or KNTC2 were significantly suppressed, and flow cytometry analyses revealed significant increases of the subG1 fractions after knockdown against both genes. Our present results suggest that expressional control of component molecules of Ndc80 can be utilized for molecular target therapy of patients with CRC and GC.

Alternative pre‐mRNA splicing in digestive tract malignancy

Alternative precursor messenger RNA (pre‐mRNA) splicing plays an important role in the generation of functional diversity of the genome. The process of pre‐mRNA splicing is regulated by cis‐ and trans‐elements, and their deregulations result in aberrantly spliced individual variants and aberrant expression profiles. Accumulating evidence has revealed that aberrant splicing contributes to a number of diseases including human neoplasms. It is well known that germ line mutations in the cis‐element of tumor suppressor genes such as mismatch repair (MMR) genes, the adenomatous polyposis coli (APC) gene and the E‐cadherin (CDH1) gene are involved in Lynch syndrome, familial adenomatous polyposis and hereditary diffuse gastric cancer, respectively. In addition, somatic mutations in cis‐elements also play a role in tumorigenesis. These genetic alterations including nonsense, missense or silent mutations in cis‐elements led to aberrant transcripts by exon skipping, retention of the intron or introduction of a new splice site. The majority of erroneous transcripts with a premature termination codon are eliminated through nonsense‐mediated mRNA decay. However, it is difficult to accurately predict the resulting transcripts with current in silico strategies. Correct interpretation of genetic alterations and the investigation of aberrant transcripts are crucial for genetic diagnosis of hereditary diseases and elucidation of the molecular characteristics of neoplasms from a clinical point of view. In this review we summarize the current knowledge of the regulatory mechanism underlying alternative pre‐mRNA splicing and aberrant splicing, with particular focus on digestive tract malignancies. (Cancer Sci 2011; 102: 309–316)

Effects of ileal interposition on glucose metabolism in obese rats with diabetes

BACKGROUND Ileal interposition (IT), in which the distal ileum is transposed isoperistaltically into the proximal jejunum, is considered as a procedure for metabolic or antidiabetes surgery. Our aim was to study the effects of IT on glycemic control, fat metabolism, and hormonal changes in obese rats with spontaneous diabetes. METHODS Animals were divided into either an IT or a sham (SH) group. They underwent an oral glucose tolerance test (OGTT) before and 4 and 8 weeks after the operation. All animals were killed 10 weeks after operation for analyses of tissue weight (liver, pancreas, epididymal fat, brown fat), immunoblotting of uncoupling protein-1 (UCP1) protein in brown adipose tissue (BAT), and fasting plasma levels of glucose, insulin, glucagon-like peptide (GLP)-1, peptide YY (PYY), glucose-dependent insulinotropic polypeptide (GIP), and leptin. RESULTS Body weight increased postoperatively in both groups compared with preoperative weight, but it did not differ between the 2 groups. Eight weeks postoperatively, integrated blood glucose levels during the OGTT were decreased in IT compared with SH (P < .05). Fasting plasma levels of insulin, GLP-1, and GIP did not differ between the 2 groups, but PYY levels were higher in the IT animals (P < .01). The weight of epididymal and BATs, homeostasis model assessment insulin resistance, and fasting plasma leptin levels were decreased in the IT group (P < .05). Expression of UCP1 was higher in IT than SH animals (P < .05). CONCLUSION These results suggest that IT improves glucose and lipid metabolism by decreasing insulin resistance and epididymal fat, and increased expression of UCP1 in BAT might be among the mechanisms responsible.

Cronkhite-Canada syndrome complicated with huge intramucosal gastric cancer

Cronkhite-Canada syndrome (CCS) is a rare nonhereditary disorder with gastrointestinal polyposis and associated ectodermal changes. This report documents a 59-year-old Japanese man with CCS who underwent a total gastrectomy for gastric tumors. The resected specimen showed a huge gastric adenocarcinoma with numerous polyps throughout the stomach. The cancer was pathologically limited to within the mucosa and its histological structure resembled that of hyperplasia in CCS polyps, which led us to suppose that the carcinoma had arisen from hyperplastic CCS polyps. These results urged us to study the phenotypic expression of mucins, which revealed MUC2(−) and MUC5AC(+) and supported the diagnosis of the tumor as a gastric-type well-differentiate adenocarcinoma. A literature search revealed that 32 gastric carcinomas which developed in patients with CCS were mostly limited to within the submucosa in spite of their huge sizes, and such cancer development in CCS polyposis is therefore not considered to be unusual.

S-1 as a core anticancer fluoropyrimidine agent

Introduction: 5-FU is a core anticancer agent for GI and other malignancies, and infusional 5-FU regimens have been widely utilized. Orally administrable fluoropyrimidine prodrugs have been developed to enhance the anticancer efficacy of 5-FU and to reduce its adverse reactions. Areas covered: S-1 is an FT-based oral 5-FU prodrug in combination with a DPD inhibitor (CDHP) and an OPRT inhibitor (Oxo), which exerts the following effects: i) maintaining normal gut immunity, Oxo can decrease GI toxicities of 5-FU; ii) sustaining high plasma 5-FU concentrations, Cmax of FBAL after S-1 administration is extremely low, which dramatically decreases adverse reactions such as HFS, neurotoxicities and cardiotoxicities; iii) plasma 5-FU concentrations vary less extensively after S-1 administration and iv) S-1 can be safely administered to patients with DPD deficiency. Furthermore, the alternate-day S-1 administration can reduce the GI toxicities and myelotoxicities of 5-FU without reducing its anticancer efficacy, enabling patients to continue the oral administration for 6 – 12 months. Expert opinion: Replacement of regimens with infusional 5-FU and other fluoropyrimidines by the alternate-day S-1 administration may be recommended because the latter procedure is efficient for patients while sustaining the enhanced anticancer efficacy of 5-FU and without reducing its dose intensity.