Regulation of Wilms Tumor Growth C4634: FY25 Regulation of Wilms Tumor Growth

ABSTRACT Wilms tumor is the most common renal malignancy in children. Although the long-term survival rates for Wilms tumor patients who exhibit localized disease are high, the treatment of the patients is associated with morbidity and many patients exhibit late effects in life even after they recover. Additionally, Wilms tumors with anaplastic histology are associated with higher rates of recurrence, metastases, and death. To address the challenge of resistance to treatment in the high-risk patients and also prevent the long-lasting side effects of chemotherapy and radiation, new drugs are needed that are more potent and effective either on their own or in combination with the standard of care treatment in mitigating tumor growth and metastasis, and have minimal long-term complications. We and others have shown that the Par-4 tumor suppressor protein induces apoptosis in cancer cells but not in normal cells. Par-4 elicits intracellular as well as extracellular effects. Elevated levels of intracellular Par-4 protein in the cytoplasm or nucleus induce apoptosis in cancer cells, and secreted Par-4 from normal cells induces apoptosis in cancer cells by binding to its cell surface receptor (cs)GRP78. Several reports have indicated that csGRP78 is expressed primarily in cancer cells and in only a few normal cells such as monocytes and cancer stromal cells. We identified small molecule secretagogues, Arylquin-1 and chloroquine that induce Par-4 secretion from normal cells in mouse models or cancer patients in clinical trials, respectively, and noted that elevated levels of systemic Par- 4 induced by these secretatgogues cause apoptosis of tumors without harming the normal tissue cells. Safety of the Par-4 secretagogues is demonstrated by the absence of overt toxicity in mice and cancer patients. Importantly, transgenic mice overexpressing Par-4 are resistant to spontaneous, as well as induced tumor growth, and have a longer life span compared to control mice that express normal levels of Par-4. We propose to test an analogue of Arylquin-1 designated Arylquin-116 that is far more potent (IC50 = 0.5 µM) than Arylquin-1 (IC50 > 2 µM) for inhibition of Wilms tumors in mouse models. Studies on Arylquin-116 and its analogues in this Supplemental proposal will add depth to the research on Arylquin-1 proposed in the PCRTF parent application. Our approach involves generating a structure- activity relationship for Arylquin-116 to produce new derivatives with chemical substitutions that impart increased potency. Specifically, our studies will generate and test potent analogues of Arylquin-116 that induce cell death at very low nanomolar concentrations, determine whether they induce cancer cell death by Par-4 secretion-based mechanism or another independent mechanism, identify the direct target protein regulated by the analogues, and finally test whether they are effective in inhibition of Wilms tumors in mice without harming normal tissues. In addition to inducing Par-4 secretion that can produce growth inhibition, Arylquin-1 and Arylquin-116 inhibit the expression of the tyrosine kinase AXL that functions downstream of the WNT/β- catenin pathway involved in growth, progression, invasion, and metastasis of cancer cells. However, Arylquin-116 is far more potent than Arylquin-1 in inducing cancer cell death, implying that Arylquin- 116 must function by a mechanism that partly overlaps yet is distinct from that of Arylquin-1. Our studies are expected to identify the binding partner of Arylquin-116 that is distinct from that of Arylquin-1, and provide a better understanding of the mechanisms that can be invoked to kill Wilms tumor cells without the side effects noted with current chemotherapy or external bean radiation treatment. The findings will provide the biological and mechanistic framework for developing Arylquin-116 or its most potent analogues for robust growth inhibition of Wilms tumor and reinforce the impact of the parent grant in developing new and safe treatments especially for the high-risk childhood cancers.