Povezanost učestalosti BRAF V600E mutiranih alela sa stupnjem proširenosti papilarnog karcinoma štitnjače

doctoral thesis

• Title (english): Association of BRAF V600E mutant allele proportion with the dissemination stage of papillary thyroid cancer
• Author: Ivan Blažeković
• Mentor: Tomislav Jukić (mentor)
• Mentor: Ivan Šamija (komentor)
• Committee member: Dražen Huić (predsjednik povjerenstva)
• Committee member: Koraljka Gall Trošelj (član povjerenstva)
• Committee member: Leo Pažanin (član povjerenstva)
• Granter: University of Zagreb; School of Medicine; Zagreb
• Defense date and country: 2023-04-04, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Clinical Medical Sciences; Oncology
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Clinical Medical Sciences; Nuclear Medicine
• Universal decimal classification (UDC): 616 - Pathology. Clinical medicine

Abstract

Jedan od primarnih izazova u liječenju učestalog, no najčešće indolentnog papilarnog karcinoma štitnjače (PKŠ), je mogućnost ranijeg identificiranja agresivnijih oblika bolesti. Proširenost bolesti u obliku udaljenih metastaza je glavni čimbenik koji utječe na preživljenje bolesnika. Upotreba molekularnih biljega poput BRAF V600E mutacije korisna je kao pokazatelj stupnja rizika za recidiv bolesti. Postojanje heterogenosti BRAF V600E mutacije u primarnom tumoru, kao i njen utjecaj na stupanj proširenosti PKŠ, nisu razjašnjene.
Cilj ovoga istraživanja je utvrditi povezanost učestalosti BRAF V600E mutiranih alela u stanicama PKŠ sa stupnjem proširenosti bolesti.
Navedeni cilj je postignut određivanjem postojanja mutacije V600E gena BRAF u primarnom tumoru metodom qPCR te kvantifikacijom mutiranih alela i njihovom normalizacijom u odnosu na procijenjeni udio stanica tumora u tkivu. Potvrdni eksperiment metode qPCR na proteinskoj razini je proveden u obliku semikvantitativne imunohistokemijske analize BRAF V600E mutiranog proteina.
Analizom 173 uzroka PKŠ utvrđena je prisutnost BRAF V600E mutacije u 60% bolesnika. Ustanovljeno je i postojanje heterogene distribucije mutacije s normaliziranim udjelom mutiranih alela BRAF u rasponu od 1.55% do 92,06%. Statističkom analizom nije utvrđena značajna povezanost postojanja mutacije BRAF V600E , kao niti udjela mutiranih alela, sa stupnjem proširenosti bolesti. Ukoliko su u statističku analizu uključene i ostale patohistološke karakteristike tumora, postojanje BRAF mutacije nije statistički značajno povezano s analiziranim karakteristikama primarnog tumora osim s angioinvazijom, dok udio mutiranih alela gena BRAF nije pokazao statistički značajnu povezanost. Dob i spol bolesnika također nisu značajno povezani niti s postojanjem, niti s udjelom mutiranih alela BRAF. Pokazana je podudarnost detekcije mutacije BRAF metodom qPCR i imunohistokemijskom analizom BRAF V600E mutiranog proteina. Rezultati istraživanja upućuju na heterogenost BRAF mutacije i postojanje oligoklonalnih oblika PKŠ. S obzirom na učestalost BRAF mutacije i njenu nepovezanost sa stupnjem proširenosti bolesti, kao i većinom nepovoljnih patohistoloških karakateristika bolesti, moguće je da BRAF mutacija samostalno nije dovoljna za procjenu agresivnosti PKŠ.

Abstract (english)

One of the primary challenges in the treatment of papillary thyroid cancer (PTC) is early identification of more aggressive forms. Disease disemination, especially in the form of distant metastases is a major factor influencing patient survival. The use of molecular markers such as BRAF V600E mutation is useful as an indicator in risk stratification for disease recurrence. However, the heterogeneity of the BRAF V600E mutation in the primary tumor and its influence on PTC disemination have not been deciphered. The aim of this study was to determine the association of the frequency of mutated BRAF V600E alleles in PTC with disease disemination.
The BRAF V600E gene mutation in the primary tumor was quantified by qPCR and normalized using the estimated proportion of tumor cells. Semiquantitative immunohistochemical analysis of the BRAF V600E mutant protein was also performed.
Analysis of 173 PTCs revealed the presence of the BRAF V600E mutation in 60% of patients. Normalized frequency of mutated BRAF alleles was from 1.55% to 92,06%. There was no significant association between the presence nor proportion of the BRAF V600E mutation with the degree of disease disemination. The presence of the BRAF mutation was not significantly associated with studied pathohistological tumor characteristics except angioinvasion. Age and sex also did not present significant association with BRAF mutation or proportion of BRAF mutated alleles. Detection of the BRAF mutation by qPCR and immunohistochemical analysis were in agreement.
The results of the study suggest the heterogeneity of the BRAF mutation and the existence of oligoclonal forms of PTC. However, given the frequency of BRAF mutation in PTC and the lack of association with both the disease disemination and majority of unfavorable pathohistological characteristics of the disease, it is possible that the BRAF mutation alone is not sufficient to assess the aggressiveness of PTC.

• Keywords: protoonkogeni proteini B-raf; aleli; papilarni rak štitnjače; mutirani proteini
• Keywords (english): proto-oncogene proteins B-raf; alleles; papillary thyroid cancer; mutant proteins
• Language: croatian
• URN:NBN: urn:nbn:hr:105:236266
• Study programme: Title: Biomedicine and Health Sciences; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje biomedicine i zdravstvo (doktor/doktorica znanosti, područje biomedicine i zdravstvo)
• Type of resource: Text
• Extent: 95 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-04-19 12:37:05