Chikashi Ishioka

Dr. Chikashi Ishioka

orcid

Research Focus & Metrics

Academic Career Length

35Years (1992-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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25 June 2003 in Proceedings of the National Academy of Sciences
Verified
Journal Article
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SKShunsuke Kato
Shunsuke Kato
SHShuang-Yin Han
Shuang-Yin Han
WLWen Liu
Wen Liu
KOKazunori Otsuka
Kazunori Otsuka
HSHiroyuki Shibata
Hiroyuki Shibata
CIChikashi Ishioka
Chikashi Ishioka
Inactivation of the tumor suppressor p53 by missense mutations is the most frequent genetic alteration in human cancers. The common missense mutations in the TP53 gene disrupt the ability of p53 to bind to DNA and consequently to transactivate downstream genes. However, it is still not fully understood how a large number of the remaining mutations affect p53 structure and function. Here, we used a comprehensive site-directed mutagenesis technique and a yeast-based functional assay to construct, express, and evaluate 2,314 p53 mutants representing all possible amino acid substitutions caused by a point mutation throughout the protein (5.9 substitutions per residue), and correlated p53 function with structure- and tumor-derived mutations. This high-resolution mutation analysis allows evaluation of previous predictions and hypotheses through interrelation of function, structure and mutation.

10 April 2018 in Oncotarget
Verified
Journal Article
Open access
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AOAkira Okita
Akira Okita
STShin Takahashi
Shin Takahashi
KOKota Ouchi
Kota Ouchi
MIMasahiro Inoue
Masahiro Inoue
MWMika Watanabe
Mika Watanabe
CIChikashi Ishioka
Chikashi Ishioka
Consensus molecular subtypes classification of colorectal cancer as a predictive factor for chemotherapeutic efficacy against metastatic colorectal cancer Consensus molecular subtypes classification of colorectal cancer as a predictive factor for chemotherapeutic efficacy against metastatic colorectal cancer

3 February 2024 in ESMO Open
Verified
Journal Article
Open access
KSKohei Shitara
Kohei Shitara
TFTania Fleitas
Tania Fleitas
HKH. Kawakami
H. Kawakami
GCGiuseppe Curigliano
Giuseppe Curigliano
YNYukiya Narita
Yukiya Narita
ESE. Smyth
E. Smyth
The European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with gastric cancer (GC), published in late 2022 and the updated ESMO Gastric Cancer Living Guideline published in July 2023, were adapted in August 2023, according to previously established standard methodology, to produce the Pan-Asian adapted (PAGA) ESMO consensus guidelines for the management of Asian patients with GC. The adapted guidelines presented in this manuscript represent the consensus opinions reached by a panel of Asian experts in the treatment of patients with GC representing the oncological societies of China (CSCO), Indonesia (ISHMO), India (ISMPO), Japan (JSMO), Korea (KSMO), Malaysia (MOS), the Philippines (PSMO), Singapore (SSO), Taiwan (TOS) and Thailand (TSCO), coordinated by ESMO and the Japanese Society of Medical Oncology (JSMO). The voting was based on scientific evidence and was independent of the current treatment practices, drug access restrictions and reimbursement decisions in the different Asian regions represented by the 10 oncological societies. The latter are discussed separately in the manuscript. The aim is to provide guidance for the optimisation and harmonisation of the management of patients with GC across the different regions of Asia, drawing on the evidence provided by both Western and Asian trials, whilst respecting the differences in screening practices, molecular profiling and age and stage at presentation. Attention is drawn to the disparity in the drug approvals and reimbursement strategies, between the different regions of Asia.

22 June 2017 in PLOS ONE
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Journal Article
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MTMasanobu Takahashi
Masanobu Takahashi
KKKeigo Komine
Keigo Komine
HYHideharu Yamada
Hideharu Yamada
YKYuki Kasahara
Yuki Kasahara
SCSonoko Chikamatsu
Sonoko Chikamatsu
CIChikashi Ishioka
Chikashi Ishioka
Some elderly cancer patients, even with good Eastern Cooperative Oncology Group performance status (ECOG-PS), have poor survival outcomes and cannot tolerate standard therapy. Few studies have detailed the associations between the G8 screening tool, ECOG-PS, and overall survival (OS) in such patients. Cancer patients, aged 70 years or older, were assessed for G8 and classified into three groups according to their G8 score: 14 as the high score group. We retrospectively analyzed the association between G8 score and OS in all patients and for each ECOG-PS-categorized group. Out of 264 enrolled patients, most patients (87%) with solid tumor were categorized as TNM stage IV. ECOG-PS was 0 or 1 in 215 patients and ≥2 in 48; there was missing data for one patient. Among all patients, the low score group with a median OS of 7.7 months survived significantly less than both the high score group with a median OS of 25.6 months [Hazard ratio (HR) 3.48; 95% confidence interval (CI), 1.96–6.63; p < 0.0001] and the intermediate score group with a median of 15.6 months (HR 1.83; 95% CI, 1.28–2.65; p < 0.001). In the multivariate analysis, TNM stage and G8 score were independent prognostic factors for OS. When patients with an ECOG-PS of 0 or 1 were analyzed, patients with a lower G8 score showed significantly shorter OS than patients with a higher score when any two groups were compared. This novel classification of the G8 score contributes to prompt identification of patients with poor prognosis and improved the prognostic value of ECOG-PS. Using G8 with ECOG-PS may be helpful in deciding treatment for elderly patients with advanced cancer.

20 June 2005 in Oncogene
Verified
Journal Article
Closed access
TKTomohiro Kawaguchi
Tomohiro Kawaguchi
SKShunsuke Kato
Shunsuke Kato
KOKazunori Otsuka
Kazunori Otsuka
GWGou Watanabe
Gou Watanabe
TKToshihiro Kumabe
Toshihiro Kumabe
CIChikashi Ishioka
Chikashi Ishioka

15 March 2005 in Cancer Research
Verified
Journal Article
Closed access
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YKYuichi Kakudo
Yuichi Kakudo
HSHiroyuki Shibata
Hiroyuki Shibata
KOKazunori Otsuka
Kazunori Otsuka
SKShunsuke Kato
Shunsuke Kato
CIChikashi Ishioka
Chikashi Ishioka
Tumor suppressor p53-dependent apoptosis is thought to be one of the most important tumor-suppressive functions in human tumorigenesis. However, whether the major mechanism underlying the p53-dependent apoptosis is transactivation dependent or independent remains unclear. Using 179 mutant p53s with diverse transcriptional activities for distinct p53-binding sequences in yeast, we evaluated both their sequence-specific transcriptional activities on six p53 target genes and their ability to induce apoptosis in Saos-2 cells. These mutant p53s also represented diversity in their ability to both transactivate target genes and induce apoptosis. We identified 17 mutant p53s with superior ability to induce apoptosis than wild-type p53 that tend to cluster at residues 121 or 290 to 292. There was no significant correlation between the two functional properties on any single target gene examined. Furthermore, the 17 mutant p53s were not classified in a specific cluster by hierarchical cluster analysis on their diverse transcriptional activities, indicating that these mutant p53s were not similar in the transcriptional activity of downstream genes. These results suggested that transactivation-dependent apoptosis does not always play a major role in p53-dependent apoptosis, indirectly supporting the importance role of the transactivation-independent mechanism.