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Chronic myeloid leukemia granulocytes exhibit reduced actin polymerization after chemotactic peptide stimulation
A Tarachandani1, S H Advani, A N Bhisey
1Cancer Research Institute, Bombay, India.
Abstract:
Polymorphonuclear leukocytes (PMNL) from chronic myeloid leukemia (CML) patients are defective for chemotaxis in response to the synthetic chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (fMLP) as compared to normal PMNL. The present study investigated whether the defective chemotactic response was mediated through altered actin polymerization induced with fMLP. Granulocytes isolated from seven normal subjects and seven CML patients were stimulated with fMLP and lysed with Triton containing buffer at time points of 0, 30 seconds, and 1, 2, and 10 minutes. The Triton insoluble cytoskeleton containing polymerized actin was analyzed by SDS-PAGE and densitometry. The CML PMNL polymerized significantly lesser actin than normal PMNL on stimulation with 10 nM (p > 0.05) and 1 nM (p > 0.01) fMLP. This lower actin polymerization observed in fMLP-stimulated CML PMNL may be responsible for the defective chemotaxis seen in these cells.
Insights
Chronic myeloid leukemia (CML) polymorphonuclear leukocytes (PMNL) show defective chemotaxis due to impaired actin polymerization. This study reveals CML PMNL exhibit reduced actin polymerization in response to fMLP, explaining their impaired cell movement.
Area of Science:
- Hematology
- Cell Biology
- Biochemistry
Background:
- Polymorphonuclear leukocytes (PMNL) from chronic myeloid leukemia (CML) patients exhibit defective chemotaxis.
- The synthetic chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (fMLP) is used to study PMNL function.
Purpose of the Study:
- To investigate if defective chemotaxis in CML PMNL is due to altered actin polymerization induced by fMLP.
- To compare actin polymerization dynamics between normal and CML PMNL upon fMLP stimulation.
Main Methods:
- Granulocytes were isolated from seven normal subjects and seven CML patients.
- Cells were stimulated with fMLP (10 nM and 1 nM) and lysed at various time points (0-10 minutes).
- Triton insoluble cytoskeleton, containing polymerized actin, was analyzed using SDS-PAGE and densitometry.
Main Results:
- CML PMNL demonstrated significantly less actin polymerization compared to normal PMNL after fMLP stimulation.
- This reduction in actin polymerization was observed at both 10 nM (p > 0.05) and 1 nM (p > 0.01) fMLP concentrations.
- A time-dependent analysis revealed impaired polymerization dynamics in CML cells.
Conclusions:
- The defective chemotaxis in CML PMNL may be attributed to their impaired actin polymerization response to fMLP.
- Altered actin dynamics represent a potential mechanism underlying the functional deficits in CML leukocytes.
- Further research could explore therapeutic strategies targeting actin polymerization pathways in CML.