Selective Targeting of Estrogen Pathways in Lung Cancer Using Biomarkers

There is a growing body of literature showing that steroid hormone pathways are involved in the development and progression of lung cancer in both men and women. Primary non-small cell lung carcinomas (NSCLCs) have been found to express the estrogen receptors a and p (ERa and ER(3), the progesterone receptor (PR), and aromatase, the enzyme that synthesizes p-estradiol from steroid precursors. This project is a continuation of SPORE Project 1 from the previous grant period, where we found that non-genomic ERP signaling to epidermal growth factor receptor (EGFR) is important in mediating NSCLC growth. Co-inhibition of ER and EGFR also showed enhanced anti-tumor effects. We recentiy discovered in a lung cancer tissue microarray (TMA) that ERp is a negative prognostic indicator in NSCLC while PR is a positive prognostic indicator. We will translate these findings to optimally target steroid hormones for lung cancer treatment and to understand the mechanism of PR down-regulation in lung cancer. Specific Aim 1 will carry out an immunohistochemical (IHC) validation study of the combined association of ERP and PR with patient survival in NSCLC tumors of known EGFR and K-ras mutation status. The hypothesis of Aim 1 is that elevated ERp expression is associated with poor outcome in NSCLC, while elevated PR expression is associated with good outcome. Extent of tumor expression of EGFR and aromatase may modulate the associations of ERp and PR with NSCLC outcome. Presence of EGFR mutations or increased EGFR copy number may also modify these survival associations. Specific Aim 2 will determine which form of PR, PRA and/or PRB, is important in NSCLC survival and determine the mechanism of loss of PR expression in lung tumor cells. The hypothesis of Aim 2 is that PR subtypes A and B may by differentially involved in biology or survival of NSCLC patients and that PR may be reduced in lung tumor cells as a result of heightened growth factor signaling. Specific Aim 3 will develop an mRNA expression-based molecular classification of NSCLC by comparing gene expression arrays in tumors characterized by ERp/PR level. Specific Aim 4 will examine the relationship of pathway biomarkers that show survival effects in Aims 1-3 to clinical response in tissues from lung cancer patients enrolled in two SPORE phase II clinical trials utilizing anti-estrogens. Completion of these Aims will demonstrate which patients are most likely to benefit from treatment with anti-estrogens and provide additional survival biomarkers related to hormonal pathways for assessing aggressiveness of NSCLCs.