Gene action and cancer in eye lens.

Gene action and cancer in eye lens

The lens of the eye is an unusual tissue, constructed for transparency and lacking a blood vessel system. Ophthalmologists have observed that the lens has a special immunity to cancer, even when the nearby retina or iris has a tumor. This resistance is not an inherent property of the lens cells, but rather reflects an inaccessibility to tumor-causing agents, says Heiner Westphal of NICHD. He and his colleagues have demonstrated that a cancer-associated gene experimentally targeted to be expressed in the lens can produce malignant transformation there.

To direct gene expression in the lens, the scientists used a control region of DNA from the gene for alpha-A crystallin, a natural protein of the lens. When this control region was attached to a bacterial gene, and that DNA was injected into single-cell mouse embryos, the gene was expressed only in the lens and only at the time during development when the crystallin gene is normally active. Next the scientists attached the crystallin control region to a viral gene known to cause tumors. This DNA was injected into 50 mouse embryos, resulting in eye tumors for all 50 mice, Westphal reports.