Differential sensitivity of chemoresistant neuroblastoma subtypes to MAPK-targeted treatment correlates with ERK, p53 expression, and signaling response to U0126.

Abstract

PURPOSE:

Neuroblastoma tumors are comprised of neuroblastic (N), substrate-adherent (S), and intermediate (I) cells. Because cell growth and differentiation often involve p44/p42 mitogen-activated protein kinase (MAPK) pathway signaling, we explored MAPK signaling and growth response in three NB cell types after MAPK kinase (MEK) inhibition to evaluate the feasibility of MAPK-targeted treatment strategies.

METHODS:

Three human NB cell cultures, SH-SY5Y (N-type), BE(2)-C (I-type), and SK-N-AS (S-type), were treated in monolayer cultures with increasing concentrations of the MEK inhibitor U0126. MAPK pathway intermediates MEK and ERK, their activated (phosphorylated) forms p-MEK and p-ERK, and p53 expression were assessed by Western blot at 1 and 24 hours. At 72 hours, cell counts determined growth inhibition and DNA fragmentation ELISA assessed apoptosis.

RESULTS:

Among all three lines, total ERK and MEK expression were unaffected by U0126. However, constitutive total ERK and p53 expression were significantly greater in BE(2)-C (I-type) cells than in SH-SY5Y (N-type) and SK-N-AS (S-type). Active ERK (p-ERK) levels decreased in dose response to U0126 at 1 and 24 hours in all lines. Conversely, p-MEK levels increased with increasing U0126 concentrations at 1 hour in SH-SY5Y (N-type) and at 24 hours in all lines. BE(2)-C (I-type) cell counts decreased in concentration-dependent fashion with U0126, whereas SH-SY5Y (N-type) and SK-N-AS (S-type) showed a biphasic response with increased cell counts at 1 micromol/L U0126 and slightly decreased cell counts at 10 mumol/L U0126.

CONCLUSION:

This study demonstrates that BE(2)-C (I-type) cells exhibit greater constitutive total ERK and p53 expression than SH-SY5Y (N-type) and SK-N-AS (S-type). Although all three lines exhibit p-ERK decreases with MEK inhibition, only BE(2)-C (I-type) cells significantly decrease their proliferation with U0126 treatment. Although MEK inhibition holds promise in targeting I-type NB cells, successfully treating this heterogeneous tumor may require combining agents against N- and S-type cells.

• Authors: Andrew C Eppstein, John A Sandoval, Patrick J Klein, Heather A Woodruff, Jay L Grosfeld, Robert J Hickey, Linda H Malkas, C Max Schmidt
• Journal: Journal of pediatric surgery (J Pediatr Surg) Vol. 41 Issue 1 Pg. 252-9 (Jan 2006) ISSN: 1531-5037 [Electronic] United States
• PMID: 16410143 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Butadienes
• Enzyme Inhibitors
• Nitriles
• Tumor Suppressor Protein p53
• U 0126
• Extracellular Signal-Regulated MAP Kinases
• Mitogen-Activated Protein Kinase Kinases

Topics

• Apoptosis (physiology)
• Butadienes (pharmacology)
• Drug Resistance, Neoplasm
• Enzyme Inhibitors (pharmacology)
• Extracellular Signal-Regulated MAP Kinases (metabolism)
• Gene Expression Profiling
• Humans
• Mitogen-Activated Protein Kinase Kinases (metabolism)
• Neuroblastoma (enzymology, pathology)
• Nitriles (pharmacology)
• Phosphorylation
• Signal Transduction
• Tumor Cells, Cultured
• Tumor Suppressor Protein p53 (metabolism)