Cancer Cell Signaling

Growth Factors and Growth Factor Receptors in Cancer

• Normal tissue architecture is maintained by communication between cells, which receive signals from their surroundings through growth factors
• Growth factors are proteins released in the extracellular space, binding to specific growth factor receptors on recipient cells, triggering an intracellular signalling cascade
• Growth factor receptors are often involved in cancer, inducing differences in cell shape, survival, and motility
• Deregulation of growth factor signalling is central to the development of cancer, allowing cancer cells to generate their own internal signals to stimulate proliferation

Deregulation of Growth Factor Signalling in Cancer

• Normal cells require ligand binding for signalling, whereas cancer cells use tactics like mutations, truncation, and overexpression to deregulate receptor signalling
• This leads to constitutive, ligand-independent receptor signalling, making cancer cells independent of their environment
• Tyrosine kinase growth factor receptors are often altered in human tumours

Autocrine Growth Factors in Cancer

• In normal cells, growth factors are not produced by the cells that express cognate receptors
• In cancer, tumour cells can produce growth factors and express cognate receptors, creating an autocrine loop leading to uncontrolled receptor activation and cancer cell proliferation

Molecular Target Therapy: Growth Factor Receptors

• Deregulated growth factor receptor signalling is a target for cancer treatment

Hormones and Hormone Signalling in Cancer

• Hormones are signalling molecules that control development and function of many organs
• Hormones influence cancer development, and hormone signalling pathways are targets in diagnosis and treatment for a range of cancers

Estrogen and Progesterone in Cancer

• Estrogen and progesterone are essential for normal reproductive development and function
• Both hormones are implicated in the development of breast cancer, and estrogen also stimulates uterine cancer growth

Hormone Signalling

• Hormones signal through receptors, which receive a specific signal from outside the cell to cause a physiological change
• Receptors for protein hormones and small polar ligands are located at the cell membrane
• Non-polar steroid hormones passively traverse the cell membrane to activate signalling via nuclear receptors
• Nuclear receptors are ligand-activated transcription factors