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Activated RET/PTC oncogene elicits immediate early and delayed response genes in PC12 cells
D Califano1, C Monaco, G de Vita
1Centro di Endocrinologia ed Oncologia Sperimentale del C.N.R., Dipartimento di Biologia e Patologia Cellulare e Molecolare Università di Napoli Federico II, Italy.
Abstract:
The expression of the receptor-like tyrosine kinase RET is associated with tumors, tissues or cell lines of neural crest origin. In addition RET products (Ret) are involved in determining cell fate during the differentiation of the enteric nervous system and during renal organogenesis. However, as yet, no direct evidence exists to indicate that the Ret kinase activity might interfere in a specific way with cellular differentiation, or proliferation, of a neural crest derived cell line. By using two constitutively activated forms of RET (RET/PTC1 and RET/PTC3) in transient transfection experiments, we have obtained evidence that active RET could reprogramme the gene expression pattern in the rat pheochromocytoma PC12 cell line. Transcription driven by gene promoters, such as NGFI-A and vgf, which belong, respectively, to primary and delayed response genes to nerve growth factor (NGF), and by the neuron-specific enolase (NSE) promoter, is rapidly induced by the expression of activated RET oncogenes. This induction is not elicited in other non neural derived cell types tested. We also demonstrate that endogenous ras activity is required for RET induction of these neural markers. Finally, in the RET/PTC transfected PC12 cells, NGF is unable to induce further their transcription. This suggests that RET/PTC could share an intracellular signalling pathway with the NGF-receptor.
Insights
Activated RET oncogenes reprogram gene expression in neural crest cells, inducing neural markers. This suggests RET oncogenes share signaling pathways with nerve growth factor receptors, impacting cell differentiation.
Area of Science:
- Oncology
- Molecular Biology
- Neuroscience
Background:
- The receptor-like tyrosine kinase RET is linked to neural crest tumors and plays a role in nervous system and kidney development.
- Previous research lacked direct evidence on RET kinase activity's specific impact on neural crest cell differentiation or proliferation.
Purpose of the Study:
- To investigate if activated RET kinase activity can influence gene expression and differentiation in neural crest-derived cells.
- To explore the signaling pathways involved in RET-mediated cellular changes.
Main Methods:
- Transient transfection of rat pheochromocytoma PC12 cells with constitutively activated RET forms (RET/PTC1 and RET/PTC3).
- Analysis of gene transcription driven by promoters of neural-specific genes (NGFI-A, vgf, NSE).
- Assessment of endogenous ras activity and response to nerve growth factor (NGF) in transfected cells.
Main Results:
- Activated RET oncogenes rapidly induced transcription of neural markers (NGFI-A, vgf, NSE) in PC12 cells, but not in non-neural cells.
- Endogenous ras activity was essential for RET-induced neural marker expression.
- PC12 cells expressing RET/PTC showed no further transcriptional induction by NGF, suggesting pathway overlap.
Conclusions:
- Constitutively activated RET oncogenes can reprogram gene expression in neural crest-derived cells, promoting a neural phenotype.
- RET signaling likely converges with the nerve growth factor receptor pathway, influencing cellular differentiation processes.