Genetic Regulatory Network Control of Tumoricidal and Tumor Promoting Macrophage Phenotypes

Lung cancer is a leading cause of death from cancer in the United Sates. Close to 200,000 people will die of lung cancer in the United States in 2008. Notably, lung cancer rates in Kentucky are the highest in the nation. Over 50% of lung tumors belong to the non-small cell lung carcinoma subgroup (sqaumous cell, adeno and large cell carcinoma). Current treatments are not very effective and the 5 year survival rate is less than 15%. Recently, there has been interest in the role of a particular immune cell, the macrophage, in cancer. Different types of macrophages have a number of functions, including positive and negative regulation of immune responses and inflammation and tissue repair and regeneration. In solid tumors like lung cancer, macrophages are the most common non- cancer cell in the tumor stroma. There is a strong correlation between the abundance of tumor associated macrophages and poor prognosis for lung, prostate, ovarian and cervical cancers. Tumor associated macrophages are predominantly of the M2 subtype. Macrophagescan differentiate into subtypes with distinct functions. One type, classically activated or Ml macrophages, stimulate immune responses and have tumor killing abilities (tumoricidal). Another type, alternatively activated or M2 macrophages, suppress immune responses and inflammation and are not tumoricidal. Their primary function is to promote tissue repair. This includes influencing new cell growth and formation of new blood vessels (vascularization), processes that can potentially be subverted by the tumor to promote its own growth and survival. While some of the factors that influence polarization to Ml and M2 macrophages are known, little is known about the genetic regulatory networks involved in macrophage polarization. The studies described here will use state of the art analysis of the genes expressed in Ml and M2 macrophages to identify genes direct naïve macrophages to differentiate to Ml or M2 macrophages. The studies will include functional studies with a cell culture system to confirm the function of Ml and M2 specific genetic regulatory proteins and will then confirm that M2 specific regulatory genes are upregulated in macrophages taken from lung tumors in mice. Collectively, this data will fill a gap in our current understanding of the genetic regulatory networks regulating the Ml and M2 macrophage subtypes with an emphasis on their role in tumor associated macrophages. Currently, there is interest in manipulating tumor promoting M2 macrophages to become more like-tumor cidallAtmacropI ages Unfortunatefr-no--one-has-yet-considered-ntarripulating-the-genetic regulatory networks that determine the Ml and M2 status and functions of macrophages due to a lack of information about these networks. The information gained from this proposal will be useful for designing gene-therapy based approaches targeting genetic regulatory elements that specify the Ml vs. M2 status of tumor associated macrophages, with the ultimate goal of converting replacing M2 tumor associated M2 macrophages with tumoricidal Ml macrophages.