Konference: 2013 18th Congress of the European Hematology Association - účast ČR
Kategorie: Maligní lymfomy a leukémie
Téma: Chronic lymphocytic leukemia - Immune triggering and microenvironmental interactions
Číslo abstraktu: P692
Autoři: Markéta Kaucká; Mgr. Pavlína Janovská; Mgr. Šárka Pavlová, PhD; Mgr. Karla Plevová, Ph.D.; Mgr. Hana Mádrová; Mgr. Lucie Poppová; prof. RNDr. Šárka Pospíšilová, Ph.D.; Mgr. Vitezslav Bryja, Ph.D.
Background: T
ransmembrane receptor tyrosine-protein kinase (ROR1) is almost uniformly uP-regulated in patients with chronic lymphocytic leukemia (CLL). ROR1 is a receptor for ligands of the Wnt family, which activate the noncanonical Wnt pathway, so called planar cell polarity - PCP-pathway. We have shown recently that PCP pathway is required for the migration of CLL cells in the chemokine gradient and the expression of PCP genes corresponds with the clinical course of CLL (Kaucka et al., Cancer Res 2013).
Aims:
In the present study we investigated the role of Wnt5a, the putative ligand of ROR1 and the activator of PCP pathway, in CLL.
Methods:
B-lymphocytes of CLL patients were negatively separated using RosetteSep (StemCell) and gradient density centrifugation. The expression of Wnt-5a was assessed by quantitative RT-PCR using B2M and actin as endogenous controls. The migration of CLL cells in chemokine gradient of CXCL12 was conducted in HTS Transwell-96 well plates.
Results:
Quantitative RT-PCR analysis of 80 CLL samples taken up to two years from diagnosis showed highly variable expression of Wnt-5a. The expression ranged from low levels comparable to healthy controls (peripheral B-cells) to high levels (102 fold change) indicating autocrine production of this ligand in a subgroup of patients. Significantly, patients with unmutated IGHV (N=46) showed higher levels of Wnt-5a (P=0.0014) which was also reflected by the worse treatment-free survival in Wnt-5a-high cohort (P<0.05). Furthermore, analysis of follow-up samples from 26 patients have shown that in several cases CLL cells uP-regulated Wnt-5a during disease progression. In patients treated in the interim, this effect was the most prominent. Functional data revealed that Wnt-5a promotes chemotaxis of CLL cells whereas inhibitors of Wnt-5a production (IWP2) block it.
Summary and Conclusions:
Based on expression analysis and functional assays we propose that Wnt-5a is a ligand of Ror1/PCP in CLL responsible for the autocrine stimulation of the PCP pathway, chemotaxis and disease progression.
Supported by 301/11/0747, NT11217-5/2010, MSM0021622430, MUNI/A/ 0723/2012, FR-TI2/254
Datum přednesení příspěvku: 15. 6. 2013
