A protein involved in cancer can also stimulate new hair growth in mice, suggesting a possible approach for curing baldness. The protein, called b-catenin, is part of a biochemical pathway that leads to most cases of colon cancer. But mice with extra b-catenin in their skin develop new hair follicles, a team reports in tomorrow's Cell.
To test whether b-catenin was involved in hair follicle development in embryos, Elaine Fuchs and her postdoc Uri Gat of the University of Chicago created mice with extra copies of the b-catenin gene. Before introducing the gene into the animals, Gat linked it to a regulatory sequence that would cause the gene to be expressed only in skin cells.
Mice with the extra b-catenin got new hair follicles even as adults. (Mice and humans normally are born with all of their hair follicles.) These follicles filled in the spaces between existing ones, but not did not appear where no hair existed before, such as on foot pads. On the dark side, however, the researchers found that benign tumors sometimes formed in the hair follicles b-catenin mice. Thus, while the demonstration that b-catenin plays a role in hair follicle formation is a "breakthrough," says Randall Moon, a developmental biologist at the University of Washington in Seattle, "we must be very careful" about b-catenin's tumor-promoting potential.
Because b-catenin activity can also contribute to tumor development, Fuchs hopes to learn which specific genes trigger hair growth, and how b-catenin activity differs in embryonic versus tumor cells. The question is, "can we separate tumorigenesis from hair follicle morphogenesis," she says. If they can, then perhaps her ideas about manipulating this growth pathway to cure baldness wouldn't be so hair-raising.
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