Supervisors info:
ΣΙΔΕΡΗΣ ΔΙΑΜΑΝΤΗΣ, Αναπληρωτής Καθηγητής, Τμήμα Βιολογίας, ΕΚΠΑ
ΣΚΟΡΙΛΑΣ ΑΝΔΡΕΑΣ, Καθηγητής, Τμήμα Βιολογίας, ΕΚΠΑ
ΚΟΝΤΟΣ ΧΡΗΣΤΟΣ, Επίκουρος Καθηγητής, Τμήμα Βιολογίας, ΕΚΠΑ
Summary:
Acute lymphocytic leukemia (ALL) is a form of a malignant neoplasm of lymphocytes, characterized by the accumulation of immature blood cells in the bone marrow. Acute leukemias are nowadays one of the most important malignant diseases, with ALL having the highest incidence rate among children aged between 2 and 5 years. Many markers are used to diagnose this disease. Ribonucleases belong to the nuclease class, which means they are molecules that degrade RNAs in smaller segments, and it has been proved that they have a crucial role in some carcinogenic events. The purpose of this postgraduate thesis is to study the expression levels of three new transcripts of the ribonuclease κ gene, in cases of children with ALL. In total, 60 patients with childhood ALL and 40 healthy controls were studied, from which total RNA was extracted from marrow samples and cDNA was synthesized by the RT-PCR reaction. The study of expression levels of the three transcripts (the 1st, the 4th and the 14th variant) was performed by quantitative real-time PCR (qPCR) analysis using the SYBR-Green I dye and then a statistical analysis took place in order to the correlate the expression levels of these variants with the clinical/pathological characteristics of each patient and their survival.
The results of the study demonstrate that the expression levels of the three transcripts are reduced in patients in comparison with the healthy (p1=0.001, pv4=0.012, pv14<0.001). As for the first transcript, it exhibits increased expression in the presence of unfavorable markers such as the B-ALL/CALLA(-) and T-ALL phenotype (p1=0.564), WBC>50.000 cells/μL and prednisone response >1000 blasts/μL (pclas = 0.124). Correspondingly, transcript 4 shows elevated levels of expression in the presence of the B-ALL/CALLA(-) and T-ALL (pv4=0.383), Philadelphia chromosome
(pv4 =0.230) and prednisone response >1000 blasts /μL (pv4=0.293). Finally, transcript 14 is overexpressed in the presence of the same markers, namely the B-ALL/CALLA (-) and T-ALL phenotype (pv14=0.304), Philadelphia chromosome (pv14=0.150) and prednisone response >1000 blasts/μL (pv14=0.420). As we can seen, transcripts 4 and 14 follow a similar pattern of expression compared to patients' clinical and pathological data, as evidenced by Spearman's correlation analysis (rs = 0.808, p<0.001).
Kaplan Meier survival analysis and Cox regression analysis show that those patients that are over-expressing the first transcript have an increased risk of death and relapse (HR=1,670, p=0,469 for DFS and HR=1,770, p = 0.408 for OS), whereas patients overexpressing transcripts 4 and 14 have an increased risk of death (HR= 2.240, p=0.254 for transcript 4 and HR=2,089, p=0,298 for transcript 14).
In conclusion, expression levels of the three transcripts, 1, 4 and 14, may provide information on the likelihood of relapse in patients with childhood ALL and can be correlated with various poor prognostic markers. It is important to note that most results are not statistically significant due to the small number of samples analyzed and this is the reason why a bigger amount of patients must be analyzed, in order to provide more reliable results.
