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| Author(s): |
Raquel Tognon Ribeiro
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2011-10-11 |
| Examining board members: |
Fabíola Attié de Castro;
Andréia Machado Leopoldino;
Katia Borgia Barbosa Pagnano;
Eduardo Magalhães Rego
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| Advisor: | Fabíola Attié de Castro |
| Abstract | |
Chronic Myeloproliferative Neoplasms (cMPN) - Essential Thrombocythemia (ET), Primary Myelofibrosis (PMF) and Polycythemia Vera (PV) - are clonal hematopoietic stem cell malignancies characterized by an accumulation of mature myeloid cells in bone marrow and peripheral blood. It seems that apoptotic machinery deregulation contribute to ET and PMF pathogenesis. Despite the advances in the molecular knowledge, the physiopathology of these diseases remains unknown. This study investigated cellular and molecular mechanisms involved in apoptosis process regulation in bone marrow haematopoietic progenitor CD34+ cells and leukocytes from ET and PMF patients. The specifics aims were: (1) to evaluate death receptors family members and Bcl-2 related genes expression as well apoptosis-related microRNAs by Real Time PCR; (2) apoptosis-related protein expression by Western Blot; (3) access mononuclear cells apoptosis resistance by flow cytometry and (4) to correlate the results with JAK2V617F mutation, PRV-1 gene expression and as well clinical data. In ET CD34+ cells, we found overexpression of a1, mcl-1, bid, bok e noxa and a decrease of bax compared to controls, while in leukocytes a1, bcl-2, bcl-w e bcl-xL, bad e bok expression was increased and bid and bimEL expression was lower than in controls. In PMF, a1, bcl-w bak, bok e noxa were overexpressed and bcl-2 downregulated in CD34+ cells. In PMF leukocytes bcl-2, bcl-w e bcl-xL, bad e bok mRNA levels were increased. c-iap-1 was increased in ET and PMF CD34+ cells and c-iap-2 expression elevated in ET and PMF CD34+ cells and leukocytes. Death receptor related genes showed overexpression of fas, fas-L, faim and dr4 in patients CD34+ cells and downregulation of fas-L and trail in ET and PMF leukocytes. We found differential expression of several genes between patients JAK2V617F positive and negative, as well we found correlation between gene expression and JAK2V617F allele burden, white blood cells and platelets count and splenomegaly. PRV-1 gene was overexpressed in ET and PMF leukocytes and showed correlation with JAK2V617F mutation and a1, bcl-w, bik, bax, c-iap-2 and trail gene expression. Regarding protein expression, BCL-XL was increased and TRAIL decreased in PMF leukocytes and BID was decreased in ET leukocytes. miRNA26a, let 7d e miR15a was overexpressed in ET and PMF leukocytes, while miR130b was increased only in ET and miR198 only in PMF. miR16 was downregulated in ET leukocytes comparing to controls. We also detected a resistance to apoptosis-inducers in ET and PMF lymphocytes and we observed correlation between apoptosis percentage and the expression of many studied genes. In conclusion, the results indicate the participations of Bcl-2 family genes and Death Receptor pathway genes, as well PRV-1 and JAK2V617F mutation in these disorders, which contribute to elucidate cMPN physiopathology and might lead to the discovery of new cMPN therapies and molecular markers. (AU) | |