Washington, Nov 15 : Researchers at the David Geffen School of Medicine (UCLA) have found that two genes, called p16(Ink4a) and Arf, play a major role in aging and offer resistance to cancer.
Led by Dr. Kenneth Dorshkind, the researchers found that the two genes sensitise lymphoid progenitor cells to the effects of aging, and confer resistance to leukemogenesis.
The development of blood cells, a process called Hematopoiesis involves two main pathways: myelopoiesis (the formation of the red and white myeloid cells) and lymphopoiesis (the formation of B- and T-cells).
While myelopoiesis remains constant throughout life, lymphopoiesis declines with age.
The researchers showed that older B lymphoid progenitor cells preferentially express p16(Ink4a) and Arf, which regulate cell cycle progression to effectively mediate senescence and tumor suppression in these aged cells.
On the other hand, myeloid progenitor cells consistently expressed much lower levels of these proteins.
In the study, the scientists showed that p16(Ink4a) and Arf contribute to the age-related decline in B-cell lymphopoiesis.
They also demonstrated that inhibition of p16(Ink4a) and Arf in B-cell progenitors rejuvenates their growth potential and facilitates the development of acute lymphoblastic leukemia.
The finding provides genetic insight into the high incidence of lymphoid leukemias in younger patients, as well as brings to light the fact that adult leukemias generally involve the myeloid cell lineages.
The authors said: "In addition to providing a basis for understanding the clinical presentation of lymphoid leukemias, these results raise the possibility that p16Ink4a and Arf may be potential therapeutic targets for rejuvenating the aged immune system".
The study is published in the latest issue of G and D.