MONDAY, June 15 (HealthDay News) -- Scientists may someday be able to fight lung cancer using gene therapy delivered by an inhalable spray.

In a new study, mice with lung cancer that were treated with a vaporized viral vector twice a week for four weeks had fewer, smaller tumors than untreated mice.

Researchers also found that treated mice had increased apoptosis, or programmed cell death, necessary for healthy tissues, as well as suppressed production of several proteins that contribute to cancer cell growth.

The study, by researchers at Seoul National University in Korea, appears in the June 15 issue of the American Journal of Respiratory and Critical Care Medicine.

"Aerosol delivery targets the lungs specifically and represents a noninvasive alternative for targeting genes to the lung," wrote study author Myung-Haing Cho, a professor at Seoul National University. "The delivery of genes via aerosol holds promise for the treatment of a broad spectrum of pulmonary disorders and offers numerous advantages over more invasive modes of delivery."

In the study, researchers used a lentiviral vector derived from a retrovirus able to infect non-dividing cells, causing lasting genetic changes. The lentiviral vector included a carboxyl-terminal modulator protein (CTMP), which inhibits Akt signaling.

Previous research has shown 90 percent of non-small cell lung carcinomas involve the Akt signaling pathway, according to the study.

Researchers divided mice into three groups: one received the aerosolized CTMP vector, one received the vector alone and one third were untreated.

The mice treated by the CTMP vector had significantly fewer, smaller tumors.

Globally, lung cancer is the most common cause of cancer deaths. Most treatments, including surgery, radiation and chemotherapy, slow progression of the disease only temporarily.

While much research is underway on the use of gene therapy to treat lung cancer, one stumbling block has been finding delivery mechanisms that work.

"Our results demonstrated that lentivirus-mediated CTMP overexpression suppressed Akt activity and inhibited tumor progression," Cho wrote.