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Expression of stem cell factor and c-kit in human neuroblastoma. The Children's Cancer Group
P S Cohen1, J P Chan, M Lipkunskaya
1Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, CA.
Abstract:
During development, mice with mutations of stem cell factor (SCF) or its receptor c-kit exhibit defects in melanogenesis, as well as hematopoiesis and gonadogenesis. Because melanocytes derive from neural crest cells, the role of SCF and c-kit was investigated in the neural crest-derived childhood tumor neuroblastoma. Using reverse transcription-polymerase chain reaction analysis, simultaneous expression of steady-state mRNA for the SCF ligand and its receptor c-kit was found in 14 of 14 (100%) human neuroblastoma cell lines and clones and in 8 of 18 (45%) human neuroblastoma tumor samples. Functional blockade of c-kit receptors in the cell lines SK-N-BE(2) and SH-SY5Y using the mouse monoclonal anti-c-kit antibody SR-1 resulted in a significant decrease in cellular growth rate when measured by either 3H-thymidine incorporation or clonogenicity. In addition, higher levels of c-kit mRNA expression were associated with parental neuroblastoma cell lines and subclones with a neuronal (N) differentiation phenotype, whereas lower levels of c-kit mRNA were associated with neuroblastoma cell line subclones having a schwannian/glial/melanocytic pattern of differentiation. However, the differentiation phenotype of neuroblastoma cell lines was not directly altered when c-kit expression was blocked using the SR-1 antibody. In summary, these data indicate that c-kit receptor expression may play a significant role in the growth regulation of the two neuroblastoma cell lines examined and suggest that c-kit may also play a similar role in neuroblastoma growth regulation in vivo. Simultaneous expression of SCF and c-kit mRNA in both neuroblastoma cell lines and tumors implies that c-kit may act as part of an autocrine growth loop in conjunction with endogenous production of SCF in this disease.
Insights
Stem cell factor (SCF) and its receptor c-kit are expressed in neuroblastoma, suggesting a role in tumor growth. Blocking c-kit significantly decreased neuroblastoma cell growth, indicating its potential as a therapeutic target.
Area of Science:
- Developmental Biology
- Cancer Research
- Molecular Biology
Background:
- Mutations in stem cell factor (SCF) and its receptor c-kit disrupt development in mice, affecting melanogenesis, hematopoiesis, and gonadogenesis.
- Melanocytes originate from neural crest cells, the same lineage that gives rise to neuroblastoma, a common childhood tumor.
Purpose of the Study:
- To investigate the role of SCF and c-kit in neuroblastoma, a neural crest-derived tumor.
- To determine if SCF and c-kit are expressed in neuroblastoma cell lines and tumors.
- To assess the functional impact of c-kit blockade on neuroblastoma cell growth and differentiation.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect mRNA expression of SCF and c-kit.
- Neuroblastoma cell lines (SK-N-BE(2) and SH-SY5Y) were treated with an anti-c-kit antibody (SR-1) to block receptor function.
- Cellular growth was measured using 3H-thymidine incorporation and clonogenicity assays.
- Correlation between c-kit mRNA levels and differentiation phenotypes (neuronal vs. schwannian/glial/melanocytic) was analyzed.
Main Results:
- SCF and c-kit mRNA were simultaneously expressed in 100% of neuroblastoma cell lines and 45% of tumor samples.
- Blocking c-kit receptors with the SR-1 antibody significantly reduced neuroblastoma cell growth rates.
- Higher c-kit mRNA levels correlated with a neuronal differentiation phenotype, while lower levels were associated with schwannian/glial/melanocytic patterns.
- c-kit blockade did not directly alter the differentiation phenotype of the neuroblastoma cell lines.
Conclusions:
- c-kit receptor expression plays a significant role in the growth regulation of neuroblastoma.
- The simultaneous expression of SCF and c-kit suggests a potential autocrine growth loop in neuroblastoma.
- These findings indicate that c-kit may be a therapeutic target for neuroblastoma growth regulation in vivo.