Lorem Sit Amet Dolor
Researcher: Lorem Sit Amet

123 abc lane, Townsville, ZZ 00000, USA
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Targeting Group 4 medulloblastoma via Musashi1-cell cycle inhibition
Translational
Medulloblastoma, Childhood (Brain Cancer)
Lay Summary

Despite recent progress in medulloblastoma treatment, two main problems remain. High risk groups 3 and 4 medulloblastoma patients still show a high rate of mortality. Even in the case of success, patients are frequently left with devastating neurocognitive and other sequelae. Therefore, more effective and less aggressive therapies are still in demand. Our strategy starts with the mapping of gene regulators required for the survival and unique characteristics of “tumor initiating cells”. We identified the RNA binding protein Musashi1 (Msi1) as an oncogenic factor in medulloblastoma and many other tumors. Musashi1 high expression is prevalent in groups 3 and 4 medulloblastoma and correlates with poor prognosis and response to therapy. Musashi1 is required to maintain cancer phenotypes and influences chemo- and radioresistance. Our recent genomic and functional analyses established Msi1 as a critical modulator of cell cycle and DNA replication. We hypothesize that Msi1 aberrant expression produces important alterations in these processes that ultimately contribute to tumor-initiation and growth. Based on these findings, we decided to pursue Msi1 as therapeutic target and identified an inhibitor (luteolin) of its regulatory functions. Building on the success of our initial evaluation in medulloblastoma and glioblastoma cells and the knowledge we gained on Msi1 regulatory functions, we will work to establish a drug combination strategy to treat groups 4 medulloblastoma. To do so, we propose two specific Aims. In Aim 1, we will determine Msi1 most relevant target genes in cell cycle. In Aim 2, we will use a screening platform to identify the best drug combinations (cell cycle inhibitors + Msi1 inhibitor) to target group 4 medulloblastoma.

Executive Summary

Medulloblastoma is the commonest malignant brain tumor in children. Treatment with surgery, irradiation, and chemotherapy has improved survival in recent years, but patients are frequently left with devastating neurocognitive and other sequelae. More effective and less aggressive therapies are still in demand in the cases of groups 3 and 4 medulloblastoma. There is substantial evidence that tumors contain a unique population of cells with stem cell characteristics which are often named “tumor initiating cells” or “cancer stem cells”. This population is unique in respect to its central role in tumor initiation, relapse, chemo- and radio-resistance. It is often suggested that effective treatments against cancer including medulloblastoma should target regulators that are required for the viability of these cells. To identify new pathways contributing to medulloblastoma development and potentially create new routes for therapy, we have been studying oncogenic RNA binding proteins and the impact of their network of targets on cancer relevant phenotypes. Our lab identified the Musashi1 (Msi1) as such a regulator and as a main driver of medulloblastoma and glioblastoma development. In the past 10 years, we have extensively published on the topic (PMIDs: 31004009, 31342436, 30362859, 27470713, 26303183, 26100017, 23715514, 22985791, 22258704, 23914149, 22201732, 21881409, 20727204, 19258308, 18826648) and established the basis to propose Msi1 as a therapeutic target. We hypothesize that aberrant Msi1 expression is essential for tumor-initiation and growth and that blockage of its function will significantly delay or prevent tumor progression.

Musashi1 high expression is prevalent in GBM and groups 3-4 medulloblastoma and correlates with poor prognosis. We established that Msi1 is required to maintain cancer relevant phenotypes and tumor growth and is implicated in chemo- and radio-resistance. Our data indicates that Msi1 might play an active role in tumor initiation. Msi1 is enriched in tumor-initiating cells that successfully engraft when injected into SCID mouse brain, Msi1 is essential for clonogenic growth of primary human GBM and medulloblastoma cells and affects the expression of key stem cell markers. Our recent genomics studies indicated that cell cycle and division are the main biological categories regulated by Msi1 in glioblastoma and medulloblastoma. Importantly, the impact Msi1 has on cell cycle and DNA replication makes Msi1 KO cells more sensitive to inhibitors of these processes. We recently developed an inhibitor against Msi1 and obtained excellent results in assays done in GBM and medulloblastoma cells. Taking advantage of these findings, we propose to develop a combined therapeutic strategy (Msi1 + cell cycle/division inhibitors) to treat group 4 medulloblastoma.

SPECIFIC AIMS

Aim 1. Defining Musashi1 main “effector” genes in cell cycle/cell division. Msi1 regulates directly and indirectly the expression of a network of cell cycle/division genes.

Aim 1A. We will evaluate an interconnected set of Msi1 direct targets involved in cell cycle/division. We will corroborate Msi1 regulatory impact on these targets via RIP-PCR, western and qRT-PCR in group 4 medulloblastoma cells and PDX derived tumors. Next, we will evaluate via siRNA knockdown if these factors are required for the survival and growth of MB cells.

Aim 1B. Our analysis indicates that part of Msi1 effect on the expression of cell cycle/division genes is indirect. We propose to test a model in which Msi1 represses RB1, leading to the activation of E2F transcription factors (E2F1, E2F2 and E2F8) and subsequent increase in expression of cell cycle/cell division genes.

 

Aim 2. Developing a combination therapy to treat groups 4 medulloblastoma. We will expand our initial analysis, expecting to identify a highly synergistic and effective drug combination (Musashi1 inhibitor + cell cycle/division inhibitor) against group 4 medulloblastoma.

In Aim 2A, we will conduct a CRISPR based synthetic lethality screening in Msi1 KD medulloblastoma cells, focusing on cell cycle/division genes. We will look then for available inhibitors of top hits and incorporate them in the screening to be performed in the second part of this aim.

In Aim 2B, we will perform a high throughput screening (HTS) using libraries of cell cycle/division inhibitors along with Msi1 inhibitor to identify combinations producing the most dramatic effect on medulloblastoma cells.

Description of Research Proposal

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Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos. Donec faucibus, turpis sit amet maximus dapibus, sapien nisl bibendum turpis, pharetra commodo tellus libero vel nulla. Sed nec velit viverra, congue sapien et, gravida libero. Proin eget ante eget turpis egestas accumsan. Aliquam arcu nibh, aliquam rhoncus vulputate in, pellentesque at sem. Maecenas cursus tempus nibh id tempus. Mauris dolor sapien, lacinia sit amet condimentum at, dapibus eget lectus. Phasellus vel pellentesque ex. Nunc aliquam in ligula at tristique. In mollis suscipit felis eu finibus. Nullam non dignissim nibh, nec suscipit ex. Suspendisse tincidunt et mauris id finibus. Aliquam vehicula a sem quis venenatis.

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Sed hendrerit vitae purus et tempor. Aenean vitae varius velit. Nullam aliquet ipsum elit. Mauris vestibulum purus et metus imperdiet, quis gravida eros pretium. Curabitur rutrum nunc vitae tincidunt condimentum. Aenean sit amet augue velit. Nunc tristique quis lorem id pharetra. Pellentesque sollicitudin, eros sed egestas rutrum, nulla nisl sodales elit, ut imperdiet nunc lectus sit amet nulla. Ut malesuada finibus libero. Curabitur mi dolor, sollicitudin quis bibendum quis, dictum sed enim.

Pellentesque nibh erat, egestas sit amet sagittis malesuada, rhoncus at neque. Mauris maximus commodo tortor, non egestas magna finibus vitae. Sed hendrerit nulla vel venenatis tempor. Suspendisse tristique tincidunt libero et placerat. Nam tincidunt condimentum lorem, vel pharetra est iaculis sed. Nullam ac tincidunt orci. Quisque pharetra ut sem sit amet aliquam. Phasellus risus libero, varius in condimentum vel, commodo id ipsum. Aliquam in metus cursus, mattis diam ut, aliquam magna. Suspendisse facilisis dui et orci varius, suscipit facilisis augue dapibus. In eget nibh ipsum. Suspendisse eget pharetra est, quis condimentum felis. Fusce scelerisque congue libero, sed aliquam mi elementum a. Etiam scelerisque ante non auctor porta. Nam eu nunc id ex finibus dictum. Praesent dui ex, dictum ac massa eget, rutrum gravida nisi.

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Budget

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer gravida non felis non euismod. Fusce finibus aliquet consequat. Nam ac metus bibendum, iaculis purus sed, suscipit ligula. Proin et nisi libero. Mauris non urna urna. Nullam augue eros, fringilla sed mauris vitae, porta tincidunt risus. Aliquam sed tincidunt sem. Quisque lacinia quam tortor, imperdiet efficitur odio iaculis in. Sed ultricies condimentum volutpat. Vivamus dignissim faucibus porta.

Curabitur ut ipsum non odio malesuada vulputate. Morbi maximus, est eu lobortis molestie, tortor sapien hendrerit nisi, in cursus odio diam ut odio. Fusce pulvinar volutpat velit. Aliquam erat volutpat. Integer rhoncus mollis suscipit. Praesent non ipsum mollis, finibus nunc a, scelerisque nibh. In feugiat iaculis velit, eu semper lacus dignissim nec. Praesent vitae nisi leo. Cras venenatis dictum magna ut semper. Sed eget eros nibh. Sed vitae quam sed dolor faucibus elementum. Curabitur interdum porttitor finibus. Nullam tincidunt odio lectus, sit amet rhoncus libero dapibus sed. Sed mollis egestas enim, vel porta tortor volutpat eget.

Morbi orci urna, ornare non pretium eget, pulvinar eget magna. Ut consectetur efficitur varius. Fusce ac aliquet mauris, at mattis ligula. Quisque est libero, interdum id orci et, ornare luctus diam. Proin commodo lectus id accumsan blandit. Nulla eu turpis interdum, luctus ante ac, imperdiet tellus. In semper enim eu tristique aliquam.

Collaborations and Conflicts of Interest

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Curabitur ut ipsum non odio malesuada vulputate. Morbi maximus, est eu lobortis molestie, tortor sapien hendrerit nisi, in cursus odio diam ut odio. Fusce pulvinar volutpat velit. Aliquam erat volutpat. Integer rhoncus mollis suscipit. Praesent non ipsum mollis, finibus nunc a, scelerisque nibh. In feugiat iaculis velit, eu semper lacus dignissim nec. Praesent vitae nisi leo. Cras venenatis dictum magna ut semper. Sed eget eros nibh. Sed vitae quam sed dolor faucibus elementum. Curabitur interdum porttitor finibus. Nullam tincidunt odio lectus, sit amet rhoncus libero dapibus sed. Sed mollis egestas enim, vel porta tortor volutpat eget.