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Paracrine action of transforming growth factors
Abstract:
Polypeptide growth factors form a class of regulatory molecules which exert their effects by binding to specific receptors present on the cell surface. Most of the time the exact role of these factors in the healthy body is unknown. Some, like PDGF and TGF beta, seem to be involved in wound healing. Others, like EGF, promote epithelial cell growth and differentiation. The site of synthesis of most polypeptide growth factors is unknown. Their target can be identified by detecting the cells which present the specific receptors at their surface. It is though that polypeptide growth factors have a paracrine mode of action. Many different cancerous cells produce polypeptide growth factors and the appropriate receptors. Thus, they are able to stimulate their own growth in an autocrine fashion. Recently, some polypeptide growth factors and receptor genes or cDNAs have been molecularly cloned. Growth factor genes and messengers are much more complex than would be expected from the size of the polypeptide. Some cDNAs have been introduced into bacterial expression vectors and large amounts of the factors have been produced by bacteria. New tools, such as molecular probes and specific antibodies, are thus now available to investigate the production of the growth factors and their receptors. The same tools will facilitate the identification and understanding of the molecular mechanism whereby cancerous cells produce the growth factors and the appropriate receptors simultaneously. The importance of growth factors and receptors in cancer is stressed by the finding that three oncogenes are in fact the genes coding for one growth factor and two receptors. Finally, the molecular probes and the specific antibodies raised against these molecules can be used to identify precisely the growth factor(s) and receptor(s) produced abnormally in cancers. Antibodies that inhibit specifically the interaction of this very growth factor with its receptor could then be developed, thus allowing human tumour cell growth to be controlled.
Insights
Polypeptide growth factors and their receptors play a role in cell regulation and cancer. New molecular tools help understand their abnormal production in tumors, potentially leading to targeted cancer therapies.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- Polypeptide growth factors regulate cellular functions by binding to specific cell surface receptors.
- Their precise roles in healthy individuals are often unknown, but they are implicated in processes like wound healing and cell growth.
- Cancerous cells can produce these factors and receptors, leading to self-stimulation of growth (autocrine fashion).
Purpose of the Study:
- To explore the role of polypeptide growth factors and their receptors in cellular regulation and cancer.
- To highlight the significance of molecular cloning and new tools in studying these molecules.
- To investigate the potential for therapeutic interventions targeting growth factor-receptor interactions in cancer.
Main Methods:
- Molecular cloning of growth factor and receptor genes/cDNAs.
- Production of recombinant growth factors using bacterial expression vectors.
- Development and application of molecular probes and specific antibodies.
Main Results:
- Molecular tools like probes and antibodies are now available for studying growth factor and receptor production.
- These tools facilitate understanding the mechanisms of abnormal production in cancer cells.
- Three oncogenes have been identified as genes for a growth factor and two receptors, underscoring their importance in cancer.
Conclusions:
- New molecular tools enable precise identification of abnormally produced growth factors and receptors in cancers.
- Understanding these mechanisms is crucial for developing targeted cancer therapies.
- Antibodies inhibiting growth factor-receptor interactions offer a potential strategy for controlling human tumor cell growth.