New Clues to Vitamin A Resistance in Lung Cancer Found

November 15, 2005 08:41:10 PM PST

The findings appear in the Nov. 16 issue of the Journal of the National Cancer Institute.

Laboratory studies have associated vitamin A deficiency with the development of lung cancer, according to background information in the study. However, human clinical trials of retinoids -- natural and synthetic derivatives of vitamin A -- for lung cancer prevention have been mostly unsuccessful.

This study, from researchers at Dartmouth, concluded that targeting a previously unknown variant of a common retinoid receptor called RAR-beta may help restore the beneficial effects of retinoids in lung cancer cells.

They found that this variant -- called RAR-beta-1' -- was expressed in normal lung cells and in cells sensitive to retinoic acid, but was not expressed in lung cancer cells or in cells resistant to retinoic acid treatment.

When the researchers treated cancer cells with a compound called azacytidine, RAR-beta-2 expression was restored but not RAR-beta-1' expression. This suggests that RAR-beta-1' has different characteristics and functions than other known forms of RAR-beta, and that it may play a role in retinoid resistance.

"Taken together, the data presented here directly implicate a critical role for RAR-beta-1' in mediating retinoid biologic effects in the lung and perhaps other organ sites," the study authors wrote.

"The frequent expression of RAR-beta-1' in lung carcinogenesis underscores its likely important biologic or clinical role," they wrote. "Identification of pharmacologic approaches that restore RAR-beta-1' expression would provide a basis for future retinoid-based combination strategies for lung cancer therapy or chemoprevention."

More information

The U.S. National Cancer Institute has more about lung cancer.

Lupus, Rheumatoid Arthritis Raise Pregnancy Risks

November 15, 2005 08:41:10 PM PST

Stanford University researchers analyzed 2002 data from the Nationwide Inpatient Sample, which contains discharge records from representative U.S. hospitals. The researchers compared delivery outcomes and hospitalizations for nearly 3,300 women with lupus and more than 1,400 women with rheumatoid arthritis to women in the general population.

Reporting at this week's annual scientific meeting of the American College of Rheumatology in San Diego, they found that women with lupus had twice the rate of hypertensive disorders, compared to women with rheumatoid arthritis. Women with either lupus or rheumatoid arthritis had higher rates of hypertensive disorders than pregnant women in the general population.

Women with lupus or rheumatoid arthritis also faced higher rates of intrauterine growth restrictions and Cesarean delivery, the study said.

"Women with either lupus and/or rheumatoid arthritis are typically somewhat older when they become pregnant," researcher Dr. Eliza F. Chakravarty, assistant professor of medicine with Stanford's division of immunology and rheumatology, noted in a prepared statement.

"However, even after adjusting for maternal age, they run a higher risk for adverse outcomes and generally experience longer hospital stays than other women. As a result, they should be monitored carefully for the length of their pregnancies," Chakravarty said.

More information

The U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases has more about lupus and pregnancy.