Expression of immune check point (ICP) molecules on tumor cells and the host immune cells, especially T-cells present in the tumor milieu, negatively impact the cancer treatment outcome resulting in inefficient tumor eradication. Data also exist showing chemo- and radio- therapy induce ICP proteins on tumor cells and thereby contributing to inactivation of tumor infiltrating T-cells, resulting in the inability to host a robust antitumor response and culminating in treatment failure, and disease recurrence. Hence, understanding how a cancer drug impacts ICP will lead to development of new therapeutic strategies that can circumvent ICP-mediated treatment failure. One such approach is to incorporate immune check point inhibitors (ICPi) which can rekindle T-cell response and enhance the efficacy of anticancer drugs. Studies from the PI's laboratory and others have demonstrated genetic and pharmacologic inhibition of the human antigen R (HuR), an mRNA-binding protein that is overexpressed in human cancer cells, results in growth inhibition, reduction in metastasis, and in increased animal survival. While these findings support advancing HuR-targeted therapy for clinical translation, the PI's lab has recently made a serendipitous discovery showing siRNA- mediated silencing of HuR using a lipid-based nanoparticle (HuR-NP) induced programmed death-ligand (PD-L)1 expression in lung cancer cells. PD-L1 is one among several ICP proteins which when expressed by tumor cells suppress T-cell function. HuR-NP markedly induced PD- L1 mRNA and protein expression in human lung cancer cell lines. Molecular studies showed HuR binding site in the promoter region of PD-L1. Finally, a negative correlation between HuR and PD-L1 expression was observed in human lung cancer tissues. To our knowledge, apart from our own observation reported herein, there are no prior reports demonstrating the ability of HuR to regulate PD-L1 and testing of HuR-nanotherapy with PD-L1 immunotherapy for cancer. On the basis of our novel findings, we posit that combining HuR-nanotherapy with PD-L1 immunotherapy will demonstrate superior anticancer efficacy by eliciting strong immune response, and reducing disease recurrence. We will test our hypothesis with three aims: Aim 1. Determine the therapeutic benefit of LNP targeting HuR in combination with anti-PD-L1 therapy in vitro. Aim 2. Demonstrate LNP targeted HuR treatment in combination with PD-L1 immunotherapy in in vivo using lung tumor models elicits immune response and enhanced antitumor activity. Aim 3. Investigate the molecular mechanism by which LNP targeting HuR modulates PD-L1 expression in lung cancer cells.