Analiza metilacije tumor supresorskih genov pri raku glave in vratu

magistrsko delo

Staša Hamzić Gregorčič (Author), Maja Leitgeb (Mentor), Uroš Potočnik (Co-mentor), Špela Stangler Herodež (Co-mentor)

Abstract

Rak glave in vratu predstavlja heterogeno skupino malignih tumorjev. Mednje uvrščamo malignome nosu, obnosnih votlin, ustne votline, žrela, grla in žlez slinavk. Ti tumorji se med seboj razlikujejo ne le po mestu, od koder izvirajo, temveč tudi po bolezenskih znakih, histološki sliki, načinu in pogostosti metastaziranja, hitrosti napredovanja ter ne nazadanje tudi po načinu zdravljenja in izidu bolezni. Resno ogrožajo bolnikovo življenje, hkrati pa prizadenejo del telesa z izredno pomembnimi fiziološkimi funkcijami, ki so bistvenega pomena v človekovem psihičnem, emocionalnem in socialnem življenju. V nastanek raka sta vpleteni predvsem dve skupini genov, in sicer protoonkogeni in tumor supresorski geni. Prvi so med procesom karcenogeneze spodbujeni k čim večjemu izražanju, medtem ko so drugi spremenjeni tako, da je njihovo izražanje zmanjšano ali da je njihov produkt funkcionalno neaktiven. Na sam proces karcenogeneze vplivajo tudi drugi dejavniki, ki ne povzročajo sprememb v nukleotidnem zaporedju DNA in jih imenujemo epigenetski dejavniki. Epigenetski dejavniki se izražajo predvsem tako, da celico vzpodbujajo in jo stalno silijo v izražanje določenih genov. Med karcenogenezo se spremeni metilacija protoonkogenov, tumor supresorskih genov ter genov, ki so odgovorni za popravljalne mehanizme DNA v celici. Hipermetilirajo in s tem se utišajo tumor supresorski geni ter geni, odgovorni za popravljanje nastalih napak na DNA. Hipometilirajo in s tem se aktivirajo protoonkogeni in geni, odgovorni za tumorsko metastaziranje. Namen magistrske naloge je analiza mutacij in metilacije tumor supresorskih genov pri raku glave in vratu. Določali smo tudi prisotnost humanih papiloma virusov (HPV) v tumorskih vzorcih, saj je predvideno, da je status metilacije povezan s HPV povezanimi tumorji raka glave in vratu. Uporabili smo referenčne vzorce zdravega tkiva in testne vzorce tumorskega tkiva. V študijo je bilo vključenih 59 bolnikov, starih med 46 in 80 let. Okužbo s HPV smo odkrili pri petih bolnikih. Mutacije v tumor supresorskem genu predstavljajo povečano verjetnost za nastanek raka v ORL področju. Za testiranje prisotnosti mutacij v tumor supresorskem genu smo uporabili metodo metilacije specifičnega hkratnega pomnoževanja od ligacije odvisnih prob, MS – MLPA. Pri 49 bolnikih je bila ugotovoljena prisotnost metilacije v več kot enem genu. Najpogosteje hipermetilirani geni so RARB, TIMP3, DAPK1 in CDH13, in jih lahko povežemo z razvojem raka glave in vratu. Pravočasno odkrivanje mutacij v genih, povezanih z nastankom raka, je za nosilce mutacij pomembno, saj je dokazana mutacija razlog za prilagojeno klinično spremljanje in preventivne ukrepe pri nosilcih mutacije.

Keywords

rak glave;rak vratu;ORL področje;protoonkogeni;tukor supresorski geni;metilacija;hipermetilacija;HPV;MS-MLPA;

Data

Language:	Slovenian
Year of publishing:	2015
Typology:	2.09 - Master's Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[S. Hamzić Gregorčič]
UDC:	[575.224+66.095.253]:616.2/.32-006.04(043.2)
COBISS:	19445782
Views:	1708
Downloads:	233
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	METHYLATION ANALYSIS OF TUMOR SUPPRESSOR GENES IN HEAD AND NECK CANCER
Secondary abstract:	Cancer of the head and neck is characterized by a heterogeneous group of malignant tumours. These include malignancies of the nose, the paranasal sinuses, the oral cavity, the pharynx, the larynx and the salivary glands. The tumors can be differentiated not only by place of origin, but also by their symptoms, histological slides, method and frequency of metastasis, progression rate, method of treatment and the outcome of the disease. These tumors pose a serious threat to the patient's life, while affecting a part of the body that controls important physiological functions, which are an essential part of our psychological, emotional and social well-being. Two groups of genes have been shown to be involved in the development of cancer: proto-oncogenes and tumor suppressor genes. During carcinogenesis, the first type of gene increases activity, while the second type is modified to decrease activity so that its product is functionally inactive. The process of carcinogenesis is also impacted by other factors that do not cause changes within the nucleotide sequence of DNA; these compounds are called epigenetic factors. Epigenetic factors assert themselves by stimulating cells and forcing them to express certain genes. During carcinogenesis, the methylation of proto-octogens, tumor suppressor genes and the genes responsible for DNA reparative mechanisms in cells, is changed. This leads to hypermethylation, which in turn suppresses the tumor suppressor genes and the genes responsible for correcting any DNA errors. It also leads to hypomethylation and the activation of proto-oncogenes and the genes responsible for tumor metastasis. The purpose of this master's thesis is to analyse the mutations and methylation of tumor suppressor genes in cancer of the head and neck. We also determined the presence of human papilloma virus (HPV) in tumor samples, since a connection between the status of methylation and HPV-associated head and neck tumors has been predicted. We used reference samples of healthy tissue and test samples of tumor tissue. The study included 59 patients aged between 46 and 80. We discovered five instances of HPV infection in our samples. Mutations in the tumor suppressor gene suggest a greater likelihood of developing cancer in the ORL region. We used the method of methylation-specific multiplex ligation-dependent probe amplification, MS – MLPA, to test for the presence of mutations in the tumor suppressor genes. In 49 cases we found methylation in more than one gene. The most common genes to be hypermethylated are RARB, TIMP3, DAPK1 and CDH13, and these can be connected to the development of head and neck cancer. Discovering gene mutations is important for the carriers of mutations, since this provides sufficient grounds for personalized clinical monitoring and other preventive measures.
Secondary keywords:	head cancer;neck cancer;ORL region;proto-oncogenes;tumor suppressor genes;methylation;hypermethylation;HPV;MS-MLPA;
URN:	URN:SI:UM:
Type (COBISS):	Master's thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	X, 64 str.
ID:	9079002