Novel retinoid-related molecules as apoptosis inducers and effective inhibitors of human lung cancer cells in vivo.

Lung cancer causes more than 140,000 deaths annually in the United States alone, and the prognosis for non-small cell lung cancer (NSCLC) is particularly poor. Therapies using small molecules that preferentially kill lung tumor cells by inducing cellular suicide (apoptosis) would therefore be highly desirable. Retinoids have shown promise as cancer preventive and cancer therapeutic agents. Retinoid signals are mediated by two classes of nuclear receptors: the retinoic acid receptors (RAR alpha, beta, and gamma) and the retinoid X receptors (RXR alpha, beta and gamma). These receptors usually bind as heterodimers to specific DNA sequences and/or interact with other transcriptional regulators, such as AP-1 (ref. 10) to regulate gene transcription. Synthetic retinoids can be made that activate only specific portions of the complex retinoid response network and activate selective biological programs. To identify retinoids with novel biological activities, we used a high-throughput "biological activity fingerprint" screen on a large library of retinoids and retinoid-related molecules (RRMs). We identified new structures that are highly effective against lung cancer cells in vitro, inducing apoptosis. We show here for one of these compounds that it is very effective against a human NSCLC in vivo in an animal model. These new molecules show a distinct pattern of receptor signaling.

Retinoblastoma protein monoclonal antibodies with novel characteristics.

We have developed a family of monoclonal antibodies directed against the retinoblastoma gene product (p110RB). One of these monoclonal antibodies, 3C8, binds p110RB near the C-terminal end of the protein (aa886-aa905). It was characterized by immunoblotting, ELISA, fluorescence-activated flow cytometry and immunohistostaining. It was shown to be useful for the detection of p110RB in formalin-fixed and paraffin-embedded tissue sections. Because 3C8 binds outside of regions shown to be involved in p110RB interactions with other cellular proteins, it may be an especially useful reagent for the reliable detection of p110RB in tumor cells, and for the isolation by affinity chromatography of p110RB complexes with other cellular proteins.