Srcasm (sic) may cure breast, head and neck and skin cancer via gene therapy

[Lani]

Hope For Targeted Gene Therapy Of Selected Cancers


08 Nov 2006



A protein with the ironic name "Srcasm" can counteract the effects of tumor-promoting molecules in skin cells, according to new research by investigators at the University of Pennsylvania School of Medicine. Using animal models, the researchers discovered that Srcasm acts like a brake in epithelial cells, preventing uncontrolled cell growth caused by a family of proteins called Src kinases. This finding, published online in the Journal of Biological Chemistry, suggests a target for future gene therapy to treat skin, head, neck, colon, and breast cancers.

Investigators have known for decades that Src kinase proteins can promote tumor formation. Src kinase activity is elevated in most skin cancers and in common carcinomas, including those of the breast and colon. At the same time, levels of the signaling molecule Srcasm are typically low in tumor cells, notes senior author John Seykora, MD, PhD, Assistant Professor of Dermatology. The current findings show that Srcasm can reduce the amount of Src kinases in cells; they have also shown that increased activity of these kinases is associated with cancerous skin lesions.

Src kinase proteins act like messengers, sending signals that control cellular growth. Found just inside the cell membrane, they conduct signals from cell surface receptors to the proteins that promote growth. Src kinases can be activated during cell division or through mutation. If these proteins are too active, they promote rapid cell growth that can spin out of control. In skin cells, Src kinases and Srcasm are involved in signaling pathways that control cell growth and differentiation.

See Saw Action
The researchers decided to test whether Srcasm could counteract the errant effects of Src kinases. They developed strains of mice with high levels of Srcasm, which had normal skin, and other strains that over-expressed the Src-kinase called Fyn, which resulted in uncontrolled cell growth with thick, scaly, hairless plaques on the skin. These plaques, or lesions, resembled precursors of cancer. Breeding experiments with the mice indicated that high Srcasm levels counteracted the effects of Fyn.

The findings reveal that levels of Fyn and Srcasm work in a kind of see-saw - when Srcasm production is low, dangerous amounts of Fyn can build up in cells. But when Srcasm production is increased, Fyn levels go down.