The Finnish Society of Medical Genetics (Suomen lääketieteellisen genetiikan yhdistys ry., SLGY) awarded the award for young researchers for M.Sc Anni Niskakoski from Prof. Päivi Peltomäki’s group. She received the award based on her excellent talk, entitled “Gynecological cancers in Lynch syndrome” in SLGY spring meeting in March the 23rd 2018.
PhD Denis Dermadi Bebek was awarded The best journal article prize for his article: Western Diet Deregulates Bile Acid Homeostasis, Cell Proliferation, and Tumorigenesis in Colon (Cancer Res. 2017 Jun 15;77(12):3352-3363. doi: 10.1158/0008-5472.CAN-16-2860. Epub 2017 Apr 17; PMID 28416481).
The Faculty of Biological and Environmental Sciences awarded article prizes for two young researchers (doctoral student and postdoctoral researcher) for the first time in April the 4th 2018. Denis Dermadi Bebek, from Prof. Minna Nyströms group, received the award for postdoctoral researches. The prize for doctoral students was awarded for Albert Spoljaric.
Niskakoski A, Pasanen A, Lassus H, Renkonen-Sinisalo L, Kaur S, Mecklin J-P, Bützow R and Peltomäki P
Molecular alterations preceding endometrial and ovarian cancer and the sequence of events are unknown. Consecutive specimens from lifelong surveillance for Lynch syndrome provides a natural setting to address such questions. To molecularly define the multistep gynecological tumorigenesis, DNA mismatch repair gene mutation carriers with endometrial or ovarian carcinoma or endometrial hyperplasia were identified from a nation-wide registry and endometrial biopsy specimens taken from these individuals during 20 years of screening were collected. A total of 213 endometrial and ovarian specimens from Lynch syndrome individuals and 197 histology-matched (non-serous) samples from sporadic cases were available for this investigation. The specimens were profiled for markers linked to endometrial and ovarian tumorigenesis, including ARID1A protein expression, mismatch repair status, and tumor suppressor gene promoter methylation. In Lynch syndrome-associated endometrial and ovarian carcinomas, ARID1A protein was lost in 61–100% and mismatch repair was deficient in 97–100%, compared to 0–17% and 14–44% in sporadic cases (P = 0.000). ARID1A loss appeared in complex hyperplasia and deficient mismatch repair and tumor suppressor gene promoter methylation in histologically normal endometrium. Despite quantitative differences between Lynch syndrome and sporadic cases, ARID1A expression, mismatch repair, and tumor suppressor gene promoter methylation divided endometrial samples from both patient groups into three categories of increasing abnormality, comprising normal endometrium and simple hyperplasia (I), complex hyperplasia with or without atypia (II), and endometrial cancer (III). Complex hyperplasias without vs. with atypia were molecularly indistinguishable. In conclusion, surveillance specimens from Lynch syndrome identify mismatch repair deficiency, tumor suppressor gene promoter methylation, and ARID1A loss as early changes in tumor development. Our findings are clinically relevant for the classification of endometrial hyperplasias and have potential implications in cancer prevention in Lynch syndrome and beyond.
Mod Pathol. 2018 Mar 27. doi: 10.1038/s41379-018-0044-4. [Epub ahead of print]
Porkka N, Valo S, Nieminen TT, Olkinuora A, Mäki-Nevala S, Eldfors S and Peltomäki P
Genomic instability and epigenetic aberrations are important classifiers of human tumors, yet, their interrelations are poorly understood. We used Lynch syndrome (LS) to address such relationships. Forty-five tumors (11 colorectal adenomas, 18 colorectal carcinomas, and 16 ovarian carcinomas) were profiled for CpG Island Methylator Phenotype (CIMP) and somatic mutations. All tumors showed high-degree microsatellite instability. Panel sequencing of 578 cancer-relevant genes revealed the average number of 1433, 1124, and 657 non-synonymous somatic mutations per colorectal adenoma, colorectal carcinoma, and ovarian carcinoma, respectively. Genes harboring mutations with allele frequency 25 % or higher in at least 31 % of tumors were regarded to be possible drivers. Among 72 and 10 such genes identified in colorectal and ovarian tumors, respectively, the most frequently mutated genes BRD4 and MLL2 (62 % of colorectal tumors) and ARID1A (50 % of ovarian carcinomas) are involved in epigenetic regulation. The total number of somatic mutations or mutant genes per tumor were significantly associated with CIMP. Our results suggest that even in an inherited disease, tumor type-specific epigenetic changes are significant and may result from regulatory changes (CIMP) or structural events (mutations of epigenetic regulatory genes). The findings are clinically relevant since many of the affected pathways can be therapeutically targeted.
Kansikas M, Nyström M & Peltomäki P.
The mismatch repair (MMR) system is necessary for the maintenance of genomic stability. The primary role of MMR is to correct errors such as base/base mismatches and small insertions/deletions that arise during DNA (deoxyribonucleic acid) synthesis. Loss of functional MMR results in increased rates of point mutations and microsatellite instability. Post-replicative MMR is strand-specific and serves mutation avoidance. Outside replication, discrimination between old and newly synthesised DNA strands is no longer necessary, and the MMR system can be mutagenic. Such non-canonical actions of MMR are required, for example, for the generation of immunoglobulin diversity. The anti-mutator and mutator activities of MMR play important roles in human diseases. Notably, germline mutations in MMR genes cause predisposition to Lynch syndrome, whereas epigenetic inactivation of the MMR gene MLH1 underlies 15% of sporadic colorectal and other cancers.
Link to updated article. eLS, 2017.
PhD Taina Nieminen gave her Docent Lecture on September 12th 2017 at 11AM in Ympäristötalo, room 2070.
The 7th biennial International Society for Gastrointestinal Hereditary tumors Incorporated (InSIGHT) meeting was organized in Florence, Italy on 5-8th of July.
Both Prof. Minna Nyström’s and Prof. Päivi Peltomäki’s groups were represented in the meeting.
PhD, Marjaana Pussila (Prof. Nyström’s group)
M.Sc, Mariann Kasela (Prof. Nyström’s group)
M.Sc, Anni Niskakoski (Prof. Peltomäki’s group)
PhD, Satu Mäki-Nevala (Prof. Peltomäki’s group) (study based on PhD Satu Valo’s work)
M.Sc, Noora Porkka (Prof. Peltomäki’s group)
Alongside the research groups, LS CancerDiag participated in the biennial InSiGHT meeting held in Florence, Italy by sponsoring the event as well as presenting the most recent results from the DiagMMR test development.
LS CancerDiag at InSiGHT 2017
Minttu Kansikas, PhD
(Photos by Lynch syndrome Research Groups, Finland)
Public PhD defence on 16th of June 2017, at 12 noon
Biocenter 2, Lecture hall 2041
Author: M.Sc. Marjaana Pussila
University of Helsinki, Faculty of Biological and Environmental Sciences, Department of Biosciences, perinnöllisyystiede
Opponent: Professor Theodore Fotsis, MD, PhD
Foundation for Research & Technology-Hellas (FORTH)
Institute of Molecular Biology and Biotechnology (IMBB)
Department of Biomedical Research (Ioannina)
Prof. Theodore Fotsis, M.Sc Marjaana Pussila and Prof. Minna Nyström
Western-style diets (WD) high in fat and scarce in fiber and vitamin D increase risk of colorectal cancer. Here, we performed a long-term diet study in mice to follow tumorigenesis and characterize structural and metabolic changes in colon mucosa associated with WD and predisposition to colorectal cancer. WD increased colon tumor numbers, and mucosa proteomic analysis indicated severe deregulation of intracellular bile acid (BA) homeostasis and activation of cell proliferation. WD also increased crypt depth and colon cell proliferation. Despite increased luminal BA, colonocytes from WD-fed mice exhibited decreased expression of the BA transporters FABP6, OSTβ, and ASBT and decreased concentrations of secondary BA deoxycholic acid and lithocholic acid, indicating reduced activity of the nuclear BA receptor FXR. Overall, our results suggest that WD increases cancer risk by FXR inactivation, leading to BA deregulation and increased colon cell proliferation.
Cancer Res; 77(12); 3352–63. ©2017 AACR.