Metastasis is a major cause of death in patients with medulloblastoma (MB) which cannot be cured with current therapy. Despite the improvement in understanding the biology of MB, the mechanisms underlying MB metastasis remain largely unclear. The goal of this proposed project is to determine the role of CD44s in MB metastasis and progression and its underlying molecular mechanism. Recently, we found, by serendipity, that CD44 standard form (CD44s) may be linked with MB metastasis and progression. Furthermore, analyzing the correlation of expression levels of CD44 in MB specimens with overall survival probability of MB patients, we observed that elevated level of CD44 in MB patients is associated with a poor outcome. Moreover, our pilot in vitro study indicates that CD44s may contribute to MB progression by enhancing MB cell invasion in vitro and CD44s may initiate its function through regulating a set of miRNAs, e.g., miR-1260 and miR-1280, and their miRNA targets in MB cells. Our encouraging preliminary data lends credence to the hypothesis that the CD44s signaling regulates MB progress and metastasis via certain downstream targets specifically regulated by CD44s, which will be tested in our NIH R15 Academic Research Enhancement Award (AREA) application. In this proposed study, we will 1) illustrate the role of CD44s in MB cells in vitro and in vivo;and 2) determine the expression levels and functions of CD44s-regulated miRNAs and miRNA targets in MB cells.
In Aim 1, we will examine the expression of CD44s in metastatic and non-metastatic MB specimens and elucidate the biological function of CD44s through in vitro assays and in vivo model using both loss- and gain-functions strategies;
in Aim 2, we will use miRNA profiling, bioinformatics analysis, and experimental validation to dissect signaling pathways, particularly miRNAs and miRNA targets regulated by CD44s in MB cells. The proposed studies have impact in several ways. First, the proposed studies will be used as research/teaching tools for teaching undergraduate and graduate students. Second, the results gained from this project will advance our knowledge in understanding of MB metastasis and progression.
Mechanistic studies of CD44 standard form in medulloblastoma progression and metastasis Keywords: medulloblastoma, progression, metastasis, CD44, miRNA targets. Metastasis is a leading cause of death in pediatric patients with medulloblastoma (MB) and approximately 30% of patients have metastatic tumors at diagnosis. In an effort to search for the cause of MB metastasis, we analyzed the expression of CD44 in a small cohort of patients with MB and explored the role of CD44 standard form (CD44s) on cell invasion in vitro. In our preliminary study, we gained several pieces of evidence suggesting that CD44s is involved in MB metastasis. This proposed study will integrate the analysis of clinical specimens with laboratory research using in vitro MB cell lines and an in vivo orthotopic MB mouse model to elucidate the function of CD44s in MB progression and metastasis and to delineate the underlying molecular mechanism. The results obtained from this study may shed light on MB progression and metastasis, revealing novel targets for development of more effective therapeutic strategies against MB. Therefore, this study will have a strong impact on human health.