Molecular analysis of HRAS and KRAS genes in thyroid cancer in the Greek population
1. Alexandra Papadopoulou | Molecular analysis of HRAS and KRAS genes in thyroid cancer in the Greek population
1
UNIVERSITY OF THESSALY
FACULTY OF HEALTH SCIENCES
DEPARTMENT OF BIOCHEMISTRYAND BIOTECHNOLOGY
MASTER OF SCIENCE: “MOLECULAR NIOLOGY AND GENETICS
APPLICATIONS - DIAGNOSTIC MARKERS”
MASTER THESIS
MOLECULAR ANALYSIS OF HRAS AND KRAS GENES IN
THYROID CANCER IN THE GREEK POPULATION
ALEXANDRA PAPADOPOULOU
ABSTRACT
Thyroid cancer is the most common type of endocrine malignancy and its frequency
is increasing steadily over the last decades. Based on histopathological characteristics,
thyroid tumors are classified into four major types (papillary, follicular, medullary
and anaplastic), while additional variants exist between these major types, with the
most common being the follicular subtype of papillary carcinoma. Previous studies
have shown that certain signaling pathways play a fundamental role in the
pathogenesis of thyroid cancer, and thus can be considered as potential targets for
therapy. For example, activation of the MAPK signaling pathway, due to genetic
mutations, is commonly found in different types of thyroid cancer. These include
point mutations of the BRAF gene (BRAFV600E
), point mutations of the RAS (HRAS,
KRAS and NRAS) genes (codons 12, 13 and 61) as well as RET / PTC and PAX8 /
PPARγ genetic rearrangements. It should be noted that the above mutations are
reported to be mutually exclusive. Limited data are available on the frequency of
these mutations in the Greek population. The purpose of this study was to investigate
the correlation of point mutations of the KRAS gene (codons 12, 13, 61) and the
HRAS gene (codon 61) with different types of thyroid cancer in the Greek population.
The study involved 33 patients with differentiated thyroid cancer, including 11
papillary, 14 follicular variants of papillary carcinoma, 7 follicular and 2 medullary
carcinomas. The experimental procedure included the isolation of genomic DNA from
paraffin-embedded tissue biopsies, the amplification of specific regions of the RAS
genes using Polymerase Chain Reaction (PCR), and the direct sequencing of the
2. Alexandra Papadopoulou | Molecular analysis of HRAS and KRAS genes in thyroid cancer in the Greek population
2
purified PCR products. The results of the study did not identify any mutation at
codons 12, 13 and 61 of the KRAS gene and at codon 61 of the HRAS gene in all the
tested samples. However, in order to be able to draw firm conclusions, this study must
be extended to include additional mutations of the RAS and the BRAF genes, as well
as genetic rearrangements, in a larger sample population.