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Mechanisms underlying USP1-mediated bypass of EWS-FLI1 oncogene-induced replication stress in Ewing sarcoma

Award Number: R01CA263504
ORGANIZATION: NATIONAL CANCER INSTITUTE
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 08/05/2022
PERIOD OF PERFORMANCE END DATE: 07/31/2027

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Mechanisms underlying USP1-mediated bypass of EWS-FLI1 oncogene-induced replication stress in Ewing sarcoma - PROJECT SUMMARY Replication stress leading to genome instability is an early driver of tumorigenesis and has been associated with overexpression of oncogenes. In normal cells, activation of the DNA damage response (DDR) pathway serves as a barrier to tumorigenesis leading to cell cycle arrest inducing cellular senescence or cell death in response to high burden of genome instability. However, in cancer cells upon oncogene-induced replication stress the protective barrier of DDR, cell death and senescence is bypassed leading to uncontrolled cell proliferation. Therefore, deciphering the mechanisms that bypass oncogene-induced replication stress and senescence will help understand the basic science underlying disease progression and will identify new targets for therapy. Ewing sarcoma (EWS) is driven by a chromosomal translocation and in-frame gene fusion between EWSR1 and ETS family of transcription factors. In majority of the EWS cases, the chromosomal translocation results in the generation of EWS-FLI1 oncogene. EWS-FLI1 functions as an aberrant transcription factor that drives the development and progression of EWS. Expression of EWS-FLI1 oncogene leads to oncogene-induced replication stress and genome instability. However, the molecular mechanism underlying bypass of EWS-FLI1 oncogene-induced replication stress response pathways is largely unknown. Our preliminary data shows that USP1 deubiquitinase is overexpressed in EWS cell lines and tumors. USP1 regulates DDR and is required for genome stability and stem cell maintenance. We find that USP1 expression is regulated by EWS-FLI1 in EWS. Importantly, inhibition of USP1 activity using small molecule USP1 inhibitors resulted in growth arrest of EWS cell lines indicating that USP1 expression and activity is important for EWS cell proliferation and progression. Notably, USP1 depletion led to a decrease in the levels of HELLS chromatin remodeling protein. The function of USP1 or HELLS in EWS pathogenesis has not been investigated. In this study, we will examine the regulation of HELLS by USP1 deubiquitinase (Aim 1), determine the mechanism by which USP1 promotes EWS cell proliferation (Aim 2), and determine the effect of USP1 knockdown on EWS tumor formation in vivo and the efficacy of USP1 inhibition in combination with chemotherapeutic drugs at suppressing EWS cell proliferation (Aim 3). Successful completion of this study will unravel novel mechanistic insights into USP1 mediated bypass of EWS-FLI1 oncogene-induced replication stress and help evaluate USP1 targeted treatment strategies for EWS.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2025 ( Subtotal = $351,131 )
2025	2025	BOARD OF REGENTS OF THE UNIVERSITY OF NEBRASKA	4215 EMILE ST	OMAHA	NE	68105	DOUGLAS	USA	Biomedical Research and Research Training	000	4	6/26/2025	NON-COMPETING CONTINUATION	$351,131
														Subtotal = $351,131

Issue Date FY: 2024 ( Subtotal = $333,575 )
2024	2024	BOARD OF REGENTS OF THE UNIVERSITY OF NEBRASKA	987835 NEBRASKA MEDICAL CENTER	OMAHA	NE	68198	DOUGLAS	USA	Biomedical Research and Research Training	000	3	7/16/2024	NON-COMPETING CONTINUATION	$333,575
														Subtotal = $333,575

Issue Date FY: 2023 ( Subtotal = $344,109 )
2023	2023	BOARD OF REGENTS OF THE UNIVERSITY OF NEBRASKA	987835 NEBRASKA MEDICAL CENTER	OMAHA	NE	68198	DOUGLAS	USA	Biomedical Research and Research Training	000	2	7/26/2023	NON-COMPETING CONTINUATION	$344,109
														Subtotal = $344,109

Issue Date FY: 2022 ( Subtotal = $351,131 )
2022	2022	BOARD OF REGENTS OF THE UNIVERSITY OF NEBRASKA	987835 NEBRASKA MEDICAL CENTER	OMAHA	NE	68198	DOUGLAS	USA	Biomedical Research and Research Training	000	1	8/5/2022	NEW	$351,131
														Subtotal = $351,131

Grand Total All Awards = $1,379,946

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Mechanisms underlying USP1-mediated bypass of EWS-FLI1 oncogene-induced replication stress in Ewing sarcoma

Award Number: R01CA263504

ORGANIZATION: NATIONAL CANCER INSTITUTE

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 08/05/2022

PERIOD OF PERFORMANCE END DATE: 07/31/2027

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