scholarly journals Abstract 4091: Knockout of genes in the DNA mismatch repair pathway to model colorectal cancer hypermutation

2018 ◽  
Author(s):  
Abbey Y. Jin ◽  
Peter Westcott ◽  
Olivia Smith ◽  
Amanda Cruz ◽  
Mary Clare Beytagh ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Repair Pathway ◽  
Dna Mismatch ◽  
Mismatch Repair Pathway

scholarly journals Additional Evidence of Mismatch Repair Pathway As Relapse-Specific Alteration in B-Cell Precursor Acute Lymphoblastic Leukemia: Discovery of Novel Somatic Mutation in MLH1 and Establishment of New Cell Line with MLH1 Mutation

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 10-10
Author(s):  
Keisuke Kato ◽  
Ai Yoshimi ◽  
Norihito Ikenobe ◽  
Chie Kobayashi ◽  
Kazutoshi Koike ◽  
...  
Keyword(s):  
Dna Repair ◽  
Cell Line ◽  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Lymphoblastic Leukemia ◽  
Repair Pathway ◽  
Dna Mismatch ◽  
Mismatch Repair Pathway ◽  
Ion Proton ◽  
Somatic Alterations

<Introduction>Extensive molecular analysis revealed genetic alterations related to relapse such as mutations of CREEB, MSH2, or NT5C2 in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Recently Li B, et al. have established relationship between relapse-specific somatic alterations and timing of relapse (Blood 2020;135:41-55). They identified close link between alterations of DNA mismatch repair genes, including MSH2, MSH6, and PMS2 and early relapse of BCP-ALL as a result of alteration of thiopurine response and resistance to treatment. However, it remains to be clarified which subtype of BCP-ALL is prone to acquisition of particular type of relapse-specific molecular alteration. To further elucidate mechanism of recurrence we have analyzed childhood BCP-ALL cases, particularly focusing on DNA mismatch repair pathway. <Procedure> We analyzed diagnosis-relapse pair samples of recurrent 16 BCP-ALL cases, who had been treated in our institution to find single nucleotide variant (SNV), small Indel, and copy number variation in the coding exons, particularly focusing on mismatch repair pathway using the data captured by Ion AmpliSeq Exome kit and Ion Proton (Thermo Fisher Scientific, MA, USA). The identified variants were confirmed by Sanger sequence. Additionally, we performed RNA-seq using SMART-Seq Ultra Low Input RNA Kit (Clontech Laboratories, Inc, CA, USA), Ion Plus Fragment Library Kit, and Ion Proton, and in vitro cell culture of the leukemic blasts for several cases. <Result> Of several DNA mismatch repair pathway genes, we have identified somatic SNV of MLH1 in a case. The index case, three years old male had diploid BCP-ALL with t(7;9) and PAX5 alteration at diagnosis, who developed early relapse (11 months from diagnosis) and died of the disease. From the sample at 1st and 2nd relapse we have identified somatic MLH1 variant (NM_000249.4:c.901C>T;p.Gln301*). This SNV was detected in small fraction of the diagnostic sample. Furthermore, we have established permanently growing cell line, ICH-BCP-1 from the sample obtained at 2nd relapse. The doubling time is approximately 37 hours and the karyotype was, 46,XY. The same MLH1 variant was identified in the cell line. Of note is that the number of detected SNV increased rapidly at 1st relapse and 2nd relapse as suggested by function of MLH1 product. No other alteration of DNA mismatch repair pathway was observed in the cohort. As previously discovered relapse-specific alterations, we identified somatic SNV of NT5C2 in one hyperdiploid BCP-ALL case and somatic SNV of CREBBP in one hyperdiploid BCP-ALL case. The former case with SNV of NT5C2 gained deletion of IKZF1 and formation of P2RY8-CRLF2 fusion gene at recurrence. Throughout the cohort, hyperdiploid BCP-ALL cases had tendency to have RAS pathway somatic SNVs (KRAS, NRAS, FLT3, and PTPN11). In addition, one low hypodiploid BCP-ALL case had germline small Indel of TP53 and somatic SNV of RB. <Discussion> We add MLH1 alteration to the list of DNA repair pathway relapse-specific somatic alterations, further supporting the particular significance of DNA repair pathway as mechanism of BCP-ALL recurrence, probably related to massive acquisition of complex genetic alteration as a result of loss of DNA repair. In our cohort, the prevalence of previously reported relapse-specific mutation is relatively low, which may be caused by detection method and different ethnicity. Our novel cell line is useful staff for investigation to identify the role of DNA mismatch repair pathway in BCP-ALL leukemogenesis. Disclosures No relevant conflicts of interest to declare.

Exo1 Independent DNA Mismatch Repair Pathway in Hematopoiesis.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2526-2526
Author(s):  
Amar Desai ◽  
Yulan Qing ◽  
Min Liu ◽  
Jonathan Kenyon ◽  
Uchenna Nwafor ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Conflicts Of Interest ◽  
Alternative Pathway ◽  
Repair Pathway ◽  
Post Transplantation ◽  
Dna Mismatch ◽  
Mismatch Repair Pathway ◽  
Single Strand Breaks ◽  
Mispaired Bases

Abstract Abstract 2526 Poster Board II-503 The DNA mismatch repair pathway (MMR) is a fundamental process in cells that functions to correct mispaired bases and insertion/deletion loops caused by errors in replication. Failure in MMR can lead to the accumulation of mutations and carcinogenesis, notably hereditary nonpolyposis colorectal cancer (HNPCC). In hematopoiesis, loss of MMR results in methylating agent resistance and an HSC repopulation defect. Our research focused on the significance of Exonuclease 1, the enzyme responsible for excising mispaired bases in MMR. Interestingly Exo1−/− mice display a much milder pathogenic phenotype when compared to the MMR deficient MSH2−/− mice; characterized by lower mutation rates, lower levels of microsatellite instability, and in humans no association with HNPCC. These findings led us to hypothesize that the limited phenotype observed in Exo1−/− mice is due to (a) complementation through another exonuclease occurs which restores the proficiency of the MMR pathway or (b) an alternative pathway exists which allows for exonuclease independent repair. To test this hypothesis we derived primary MEFs from WT, Exo1−/− and MSH2−/− mice and performed temozolomide sensitivity assays. We observed that Exo1−/− MEFs are similarly sensitive as WT cells when treated with the drug, confirming proficient MMR, while MSH2−/− MEFs display a decreased sensitivity. Additionally, comet assays with the same cell populations show a persistence of DNA single strand breaks in the Exo1−/− and WT cells 24 hours post temozolomide treatment, consistent with proficient MMR activity, while MSH2−/− MEFs show no such damage. To confirm functional MMR in hematopoiesis of Exo1−/− mice we conducted a competitive repopulation study. We found that Exo1−/− and WT marrow engraft at similar levels 8 and 16 weeks post transplantation. We subsequently treated these mice with 80 mg/kg temozolomide to determine if Exo1−/− marrow progenitors would confer a competitive survival advantage post treatment. Consistent with our hypothesis we found that the ratio of marrow cells remained approximately 50:50 (Exo1:WT) in contrast to data obtained from MSH2−/− mice in which the MSH2−/− cells display a strong 95:5 (MSH2:WT) advantage post drug treatment. This strongly suggests functional MMR in the Exo1 deficient mice. We next coimmunoprecipitated the MMR complex by pulling down Mlh1 in Exo1−/− and WT MEFs. Exo1, a key exonuclease in mismatch repair, does not modulate hematopoietic function as do the other MMR proteins and appears to be complemented by an as yet undefined exonuclease. Disclosures: No relevant conflicts of interest to declare.

Recognition of oxidative DNA lesions by the DNA mismatch repair pathway

2003 ◽  
Vol 57 (2) ◽  
pp. S143
Author(s):  
P Hungspreugs ◽  
T.M Sofinowski ◽  
L.A Uzdilla ◽  
S.M Matthews ◽  
D.M Wilson ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Dna Lesions ◽  
Repair Pathway ◽  
Dna Mismatch ◽  
Mismatch Repair Pathway

Duodenal Reflux Leads to Down Regulation of DNA Mismatch Repair Pathway in an Animal Model of Esophageal Cancer

2007 ◽  
Vol 83 (2) ◽  
pp. 433-440 ◽  
Author(s):  
Pramod Bonde ◽  
Daqing Gao ◽  
Lei Chen ◽  
Tomoharu Miyashita ◽  
Elizabeth Montgomery ◽  
...  
Keyword(s):  
Animal Model ◽  
Esophageal Cancer ◽  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Repair Pathway ◽  
Down Regulation ◽  
Dna Mismatch ◽  
Mismatch Repair Pathway ◽  
Duodenal Reflux

Helicobacter pyloriinfection modulates the expression of miRNAs associated with DNA mismatch repair pathway

2016 ◽  
Vol 56 (4) ◽  
pp. 1372-1379 ◽  
Author(s):  
Juliana C. Santos ◽  
Mitsue T. Brianti ◽  
Victor R. Almeida ◽  
Manoela M. Ortega ◽  
Wolfgang Fischer ◽  
...  
Keyword(s):  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Repair Pathway ◽  
Dna Mismatch ◽  
Mismatch Repair Pathway

scholarly journals Therapeutic Targeting of the DNA Mismatch Repair Pathway

2010 ◽  
Vol 16 (21) ◽  
pp. 5107-5113 ◽  
Author(s):  
Sarah A. Martin ◽  
Christopher J. Lord ◽  
Alan Ashworth
Keyword(s):  
Mismatch Repair ◽  
Dna Mismatch Repair ◽  
Repair Pathway ◽  
Therapeutic Targeting ◽  
Dna Mismatch ◽  
Mismatch Repair Pathway
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