Kenji Okita

Bio: Kenji Okita is an academic researcher from Sapporo Medical University. The author has contributed to research in topics: Colorectal cancer & Medicine. The author has an hindex of 16, co-authored 68 publications receiving 1070 citations.

Association of Fusobacterium nucleatum with clinical and molecular features in colorectal serrated pathway

Abstract: Human gut microbiota is being increasingly recognized as a player in colorectal cancers (CRCs). Evidence suggests that Fusobacterium nucleatum (F. nucleatum) may contribute to disease progression and is associated with CpG island methylator phenotype (CIMP) and microsatellite instability (MSI) in CRCs; however, to date, there are no reports about the relationship between F. nucleatum and molecular features in the early stage of colorectal tumorigenesis. Therefore, we investigated the presence of F. nucleatum in premalignant colorectal lesions. In total, 465 premalignant lesions (343 serrated lesions and 122 non-serrated adenomas) and 511 CRCs were studied. We determined the presence of F. nucleatum and analyzed its association with molecular features including CIMP, MSI and microRNA-31 status. F. nucleatum was detected in 24% of hyperplastic polyps, 35% of sessile serrated adenomas (SSAs), 30% of traditional serrated adenomas (TSAs) and 33% of non-serrated adenomas. F. nucleatum was more frequently detected in CIMP-high premalignant lesions than in CIMP-low/zero lesions (p = 0.0023). In SSAs, F. nucleatum positivity increased gradually from sigmoid colon to cecum (p = 0.042). F. nucleatum positivity was significantly higher in CRCs (56%) than in premalignant lesions of any histological type (p < 0.0001). In conclusion, F. nucleatum was identified in premalignant colorectal lesions regardless of histopathology but was more frequently associated with CIMP-high lesions. Moreover, F. nucleatum positivity increased according to histological grade, suggesting that it may contribute to the progression of colorectal neoplasia. Our data also indicate that F. nucleatum positivity in SSAs may support the "colorectal continuum" concept.

Association of microRNA-31 with BRAF mutation, colorectal cancer survival and serrated pathway.

Abstract: BRAF is an important gene in colorectal cancers (CRCs) that is associated with molecular characterization and resistance to targeted therapy. Although microRNAs (miRNAs) are useful biomarkers of various cancers, the association between miRNA and BRAF in CRCs is undefined. Therefore, this study was conducted to identify a relationship between specific miRNA molecules and BRAF mutation in CRCs and serrated lesions. miRNA array was used for the measurement of 760 miRNAs in 29 CRCs. To assess the identified miRNAs, quantitative reverse transcription-PCR was performed on 721 CRCs, 381 serrated lesions and 251 non-serrated adenomas. Moreover, proliferation and invasion assays were conducted using cell lines. miRNA array analysis revealed that microRNA-31 (miR-31)-5p was the most up-regulated miRNA in CRCs with mutated BRAF (V600E) compared with CRCs possessing wild-type BRAF (including cases with KRAS mutation). High miR-31 expression was associated with BRAF and KRAS mutations and proximal location (P < 0.0001). High miR-31 expression was related to cancer-specific mortality [multivariate hazard ratio = 2.06, 95% confidence interval: 1.36-3.09, P = 0.0008]. Functional analysis demonstrated that miR-31 inhibitor decreased cell invasion and proliferation. With regard to serrated lesions, high miR-31 expression was less frequently detected in hyperplastic polyps compared with other serrated lesions. In conclusion, associations were identified between miR-31, BRAF and prognosis in CRC. Transfection of miR-31 inhibitor had an antitumour effect. Thus, miR-31 may be a promising diagnostic biomarker and therapeutic target in colon cancers. Moreover, high miR-31 expression in serrated lesions suggested that miR-31 may be a key molecule in serrated pathway.

Japanese Society of Clinical Oncology clinical practice guidelines 2010 for antiemesis in oncology: executive summary

Abstract: The purpose of this article is to disseminate the standard of antiemetic therapy for Japanese clinical oncologists. On the basis of the Appraisal of Guidelines for Research and Evaluation II instrument, which reflects evidence-based clinical practice guidelines, a working group of the Japanese Society of Clinical Oncology (JSCO) reviewed clinical practice guidelines for antiemesis and performed a systematic review of evidence-based domestic practice guidelines for antiemetic therapy in Japan. In addition, because health-insurance systems in Japan are different from those in other countries, a consensus was reached regarding standard treatments for chemotherapy that induce nausea and vomiting. Current evidence was collected by use of MEDLINE, from materials from meetings of the American Society of Clinical Oncology National Comprehensive Cancer Network, and from European Society of Medical Oncology/Multinational Association of Supportive Care in Cancer guidelines for antiemesis. Initially, 21 clinical questions (CQ) were selected on the basis of CQs from other guidelines. Patients treated with highly emetic agents should receive a serotonin (5-hydroxytryptamine; 5HT3) receptor antagonist, dexamethasone, and a neurokinin 1 receptor antagonist. For patients with moderate emetic risk, 5HT3 receptor antagonists and dexamethasone were recommended, whereas for those receiving chemotherapy with low emetic risk dexamethasone only is recommended. Patients receiving high-emetic-risk radiation therapy should also receive a 5HT3 receptor antagonist. In this paper the 2010 JSCO clinical practice guidelines for antiemesis are presented in English; they reveal high concordance of Japanese medical circumstances with other antiemetic guidelines that are similarly based on evidence.

Association of MicroRNA-31-5p with Clinical Efficacy of Anti-EGFR Therapy in Patients with Metastatic Colorectal Cancer

Abstract: Gene mutations in the pathway downstream of epidermal growth factor receptor (EGFR) are considered to induce resistance to anti-EGFR therapy in colorectal cancer (CRC). We recently reported that microRNA-31 (miR-31)-5p may regulate BRAF activation and play a role in the signaling pathway downstream of EGFR in CRC. Therefore, we hypothesized that miR-31-5p can be a useful biomarker for anti-EGFR therapy in CRC. We evaluated miR-31-5p expression and gene mutations [KRAS (codon 61 or 146), NRAS (codon 12, 13, or 61), and BRAF (V600E)] in the EGFR downstream pathway in 102 CRC patients harboring KRAS (codon 12 or 13) wild-type who were treated with anti-EGFR therapeutics. Progression-free survival (PFS) and overall survival (OS) were evaluated. KRAS (codon 61 or 146), NRAS, and BRAF mutations were detected in 6.9, 6.9, and 5.9 % patients, respectively. Compared with CRCs with at least one mutation (n = 20), significantly better PFS (P = 0.0003) but insignificantly better OS were observed in CRCs harboring all wild-type genes (KRAS, NRAS, and BRAF). High miR-31-5p expression was identified in 11 % (n = 11) patients and was significantly associated with shorter PFS (P = 0.003). In CRCs carrying all wild-type genes, high miR-31-5p was associated with shorter PFS (P = 0.027). High miR-31-5p expression was associated with shorter PFS in patients with CRC treated with anti-EGFR therapeutics. Moreover, in CRCs carrying all wild-type genes, high miR-31-5p was associated with shorter PFS, suggesting that it may be a useful and additional prognostic biomarker for anti-EGFR therapy.

Analysis of Fusobacterium persistence and antibiotic response in colorectal cancer

Abstract: Colorectal cancers comprise a complex mixture of malignant cells, nontransformed cells, and microorganisms. Fusobacterium nucleatum is among the most prevalent bacterial species in colorectal cancer tissues. Here we show that colonization of human colorectal cancers with Fusobacterium and its associated microbiome—including Bacteroides , Selenomonas , and Prevotella species—is maintained in distal metastases, demonstrating microbiome stability between paired primary and metastatic tumors. In situ hybridization analysis revealed that Fusobacterium is predominantly associated with cancer cells in the metastatic lesions. Mouse xenografts of human primary colorectal adenocarcinomas were found to retain viable Fusobacterium and its associated microbiome through successive passages. Treatment of mice bearing a colon cancer xenograft with the antibiotic metronidazole reduced Fusobacterium load, cancer cell proliferation, and overall tumor growth. These observations argue for further investigation of antimicrobial interventions as a potential treatment for patients with Fusobacterium -associated colorectal cancer.

Dynamic transcriptomic m6A decoration: writers, erasers, readers and functions in RNA metabolism.

Abstract: N6-methyladenosine (m6A) is a chemical modification present in multiple RNA species, being most abundant in mRNAs. Studies on enzymes or factors that catalyze, recognize, and remove m6A have revealed its comprehensive roles in almost every aspect of mRNA metabolism, as well as in a variety of physiological processes. This review describes the current understanding of the m6A modification, particularly the functions of its writers, erasers, readers in RNA metabolism, with an emphasis on its role in regulating the isoform dosage of mRNAs.

Rethinking m6A Readers, Writers, and Erasers.

Abstract: In recent years, m6A has emerged as an abundant and dynamically regulated modification throughout the transcriptome. Recent technological advances have enabled the transcriptome-wide identification of m6A residues, which in turn has provided important insights into the biology and regulation of this pervasive regulatory mark. Also central to our current understanding of m6A are the discovery and characterization of m6A readers, writers, and erasers. Over the last few years, studies into the function of these proteins have led to important discoveries about the regulation and function of m6A. However, during this time our understanding of these proteins has also evolved considerably, sometimes leading to the reversal of early concepts regarding the reading, writing and erasing of m6A. In this review, we summarize recent advances in m6A research, and we highlight how these new findings have reshaped our understanding of how m6A is regulated in the transcriptome.

Diffusion-weighted MR imaging of the liver.

Abstract: Magnetic resonance (MR) imaging plays an increasingly important role in the evaluation of patients with liver disease because of its high contrast resolution, lack of ionizing radiation, and the possibility of performing functional imaging sequences. With advances in hardware and coil systems, diffusion-weighted (DW) MR imaging can now be applied to liver imaging with improved image quality. DW MR imaging enables qualitative and quantitative assessment of tissue diffusivity (apparent diffusion coefficient) without the use of gadolinium chelates, which makes it a highly attractive technique, particularly in patients with severe renal dysfunction at risk for nephrogenic systemic fibrosis. In this review, acquisition parameters, postprocessing, and quantification methods applied to liver DW MR imaging will be discussed. The current clinical uses of DW MR imaging (liver lesion detection and characterization, compared and combined with conventional sequences) and the emerging applications of DW MR imaging (tumor treatment response and diagnosis of liver fibrosis and cirrhosis) will be reviewed. Also, limitations, mainly image quality and reproducibility of diffusion parameters, and future directions of liver DW MR imaging will be discussed.