Deregulation of apoptosis-related genes is associated with PRV1 overexpression and JAK2 V617F allele burden in Essential Thrombocythemia and Myelofibrosis.
BACKGROUND
Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF) are Chronic Myeloproliferative Neoplasms (MPN) characterized by clonal myeloproliferation/myeloaccumulation without cell maturation impairment. The JAK2 V617F mutation and PRV1 gene overexpression may contribute to MPN physiopathology. We hypothesized that deregulation of the apoptotic machinery may also play a role in the pathogenesis of ET and PMF. In this study we evaluated the apoptosis-related gene and protein expression of BCL2 family members in bone marrow CD34+ hematopoietic stem cells (HSC) and peripheral blood leukocytes from ET and PMF patients. We also tested whether the gene expression results were correlated with JAK2 V617F allele burden percentage, PRV1 overexpression, and clinical and laboratory parameters.


RESULTS
By real time PCR assay, we observed that A1, MCL1, BIK and BID, as well as A1, BCLW and BAK gene expression were increased in ET and PMF CD34+ cells respectively, while pro-apoptotic BAX and anti-apoptotic BCL2 mRNA levels were found to be lower in ET and PMF CD34+ cells respectively, in relation to controls. In patients' leukocytes, we detected an upregulation of anti-apoptotic genes A1, BCL2, BCL-XL and BCLW. In contrast, pro-apoptotic BID and BIMEL expression were downregulated in ET leukocytes. Increased BCL-XL protein expression in PMF leukocytes and decreased BID protein expression in ET leukocytes were observed by Western Blot. In ET leukocytes, we found a correlation between JAK2 V617F allele burden and BAX, BIK and BAD gene expression and between A1, BAX and BIK and PRV1 gene expression. A negative correlation between PRV1 gene expression and platelet count was observed, as well as a positive correlation between PRV1 gene expression and splenomegaly.


CONCLUSIONS
Our results suggest the participation of intrinsic apoptosis pathway in the MPN physiopathology. In addition, PRV1 and JAK2 V617F allele burden were linked to deregulation of the apoptotic machinery.
Department of Clinical, Toxicological and Bromatological Analysis, University of São Paulo, Ribeirão Preto, Brazil.
Raquel
R
Tognon
Elainy P L
EP
Gasparotto
Renata P
RP
Neves
Natália S
NS
Nunes
Aline F
AF
Ferreira
Patrícia V B
PV
Palma
Simone
S
Kashima
Dimas T
DT
Covas
Mary
M
Santana
Elizabeth X
EX
Souto
Maria Aparecida
MA
Zanichelli
Belinda P
BP
Simões
Ana Maria
AM
de Souza
Fabíola A
FA
Castro
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D015153:Blotting, Western; D016022:Case-Control Studies; D005260:Female; D058851:GPI-Linked Proteins / Q000378:metabolism; D006801:Humans; D007519:Isoantigens / Q000378:metabolism*; D053614:Janus Kinase 2 / Q000235:genetics*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008875:Middle Aged; D024101:Mitochondrial Proteins; D009154:Mutation / Q000235:genetics*; D055728:Primary Myelofibrosis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013920:Thrombocythemia, Essential / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051028:bcl-2-Associated X Protein / Q000378:metabolism*; D051025:bcl-Associated Death Protein / Q000378:metabolism*
D051017:Apoptosis Regulatory Proteins; C494819:BAD protein, human; C494826:BAX protein, human; C096820:BIK protein, human; C407242:CD177 protein, human; D058851:GPI-Linked Proteins; D007519:Isoantigens; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; C507924:JAK2 protein, human; D053614:Janus Kinase 2