| Abstract | Cilj istraživanja: Transkripcijski faktor povezan s mikroftalmijom (MITF) ima ključnu
ulogu u transkripciji gena koji su specifično izraženi u melanocitima i ima središnju
ulogu u regulaciji diferencijacije, rasta i preživljenja stanica melanocitne loze.
Melanom je najagresivniji tumor kože i sluznica koji nastaje malignom preobrazbom
melanocita. Ispitivanjem međusobnih odnosa proteinske ekspresije MITF-a i
molekula povezanih s regulacijom njegove biološke aktivnosti - ciklina D1 i BCL-2, te
preuredbi u genima BRAF, MITF i CCND1, istražit će se njihov funkcionalni,
dijagnostički i prognostički značaj u nodularnom melanomu (NM).
Materijali i metode: Evaluirano je ukupno 80 uzoraka bioptičkog materijala, 52
uzorka NM i 28 uzoraka displastičnih nevusa. Imunohistokemijske analize učinjene
su metodom tkivnih mikroareja (TMA). Preuredbe MITF, CCND1 i BRAF gena
analizirane su metodama polimerazne lančane reakcije (PCR) i kvantitativnog Realtime PCR-a (QRT-PCR), te sekvenciranjem Sangerovom metodom.
Rezultati: Proteinska ekspresija MITF-a, ciklina D1 i BCL-2 u NM uzorcima je
statistički značajno veća od ekspresije u displastičnim nevusima (p<0,0001).
Ekspresija MITF proteina je udružena s amplifikacijom MITF gena (p<0,001),
ekspresijom BCL-2 proteina (p=0,005) i granično s ekspresijom ciklina D1 (p=0,084).
BRAF V600 mutacije povezane su s ekspresijom ciklina D1 (p=0,018), te granično s
proteinskom ekspresijom MITF-a (p=0,083) i BCL-2 (p=0,085). Multivarijatna analiza
je pokazala da su Clark stupnjevi (4+5), debljina tumora veća od 4mm (po Breslow-u)
i proteinska ekspresija ciklina D1 (25-50%), neovisni prognostički faktori za
sveukupno preživljenje (p <0,05).
Zaključak: Unatoč činjenica da ekspresija MITF proteina i amplifikacija MITF gena
nisu statistički potvrđeni kao neovisni prognostički faktori sveukupnog preživljenja,
bolesnici s visokom ekspresijom MITF proteina (>60%) i amplifikacijom MITF gena,
imaju 2,91 (0,79–10,73; p=0,108), odnosno 1,92 (0,86-4,27; p=0,11) puta veći rizik
kraćeg sveukupnog preživljenja. |
| Abstract (english) | Aim of the study: Microphthalmia-related transcription factor (MITF) plays a key role
in the transcription of genes specifically expressed in melanocytes and plays a
central role in the regulation of melanocyte cell differentiation, growth, and survival.
Melanoma is the most aggressive tumor of the skin and mucous membranes caused
by a malignant transformation of melanocytes. By examining the relationships of
protein expression of MITF and molecules related to the regulation of its biological
activity - cyclin D1 and BCL-2, and rearrangements in the genes BRAF, MITF, and
CCND1, their functional, diagnostic, and prognostic significance in nodular melanoma
(NM) will be investigated.
Materials and methods: A total of 80 bioptic samples, 52 nodular melanoma (NM),
and 28 dysplastic nevus samples were evaluated. Immunohistochemical analyzes
were performed on tumor samples by the tissue microarray (TMA) method. Genetic
rearrangements of MITF, CCND1, and BRAF genes were analyzed by polymerase
chain reaction (PCR), quantitative PCR (QRT-PCR), and Sanger sequencing.
Results: Protein expression of MITF, cyclin D1, and BCL-2 in NM samples was
significantly higher than expression in dysplastic nevi (p<0.0001). MITF expression
was associated with MITF gene amplification (p<0.001), BCL-2 protein expression
(p=0.005), and borderline with cyclin D1 expression (p=0.084). BRAF V600 mutations
were associated with cyclin D1 (p=0.018), and borderline with MITF (p=0.083) and
BCL-2 expression (p=0.085). Multivariate analysis showed that the Clark parameter
(category 4+5), tumor thickness >4mm and cyclin D1 protein expression (25-50%),
were independent prognostic factors for overall survival (p <0.05).
Conclusion: Although MITF protein expression and MITF gene amplification were
not statistically confirmed as independent prognostic factors for overall survival,
patients with high MITF protein expression (> 60%) and MITF gene amplification had
2.91 (0.79-10.73; p= 0.108), and 1.92 (0.86-4.27; p=0.11) times higher risk of shorter
overall survival. |
