2010 — 2014 |
Lin, Hui-Kuan |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Regulation of Akt Signaling Activation by Polyubiquitination @ University of Tx Md Anderson Can Ctr
DESCRIPTION (provided by applicant): Akt/PKB signaling plays a central role in many biological functions, such as cell proliferation, apoptosis, cell metabolism, and protein translation. Although it is well known that Akt activation is regulated by phosphorylation, it is unclear whether other types of the posttranslational modifications, such as ubiquitination, are also involved in Akt activation. In this proposal, we have identified TRAF6 as a potential Akt E3 ligase that induces Akt K63-linked polyubiquitination and is critical for Akt phosphorylation and activation. Our results reveal that Akt K63 polyubiquitination may represent a novel mechanism by which oncogenic Akt signaling is regulated and that this study may have important clinical implications for the treatment of cancer. The objective of this application, which is the next step in pursuit of that goal, is to determine the potential role of TRAF6 and Akt K63-linked polyubiquitination in cancer progression and metastasis. The central hypothesis of the application is that Akt K63-linked polyubiquitination induced by TRAF6 orchestrates Akt membrane localization and subsequent phosphorylation. Our central hypothesis has been formulated on the basis of our strong preliminary data. The rationale of the proposed research is that, once the important role of TRAF6 and Akt polyubiquitination is confirmed and established in cancer progression and metastasis, the better treatment or target for human cancers can be achieved. We plan to test our central hypothesis and accomplish the objective of this application by pursuing the following specific aims: Aim 1) To determine the molecular mechanism by which Akt polyubiquitination regulates Akt activation. Aim 2) To determine the molecular mechanism by which Akt ubiquitination and deubiquitination are regulated. Aim 3) To determine in vivo role of TRAF6 in tumorigenesis and metastasis. This proposal work is innovative, because it provides for the first time that TRAF6 is an E3 ligase for Akt and Akt K63-linked polyubiquitination orchestrate Akt phosphorylation and activation. With respected outcomes, the combination of work in this proposal is collectively expected to uncover the critical role of TRAF6 and Akt K63-linked polyubiquitination in cancer development and metastasis. Such results will have an important positive impact, because identification of the important role of TRAF6 and Akt K63-linked polyubiquitination in cancer progression and metastasis may therefore provide potentially therapeutic targets for cancer treatment. Our results will also fundamentally advance our current understandings of how oncogenic Akt signaling is regulated and may have important clinical implications.
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0.958 |
2010 — 2014 |
Lin, Hui-Kuan |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
The Crosstalk Between the Pi3k/Akt Signal and Skp2 in Prostate Cancer Progression @ University of Tx Md Anderson Can Ctr
DESCRIPTION (provided by applicant): As loss of PTEN tumor suppressive function resulting in aberrant Akt activation is a prevalent event in human cancers and associated with cancer metastasis, it is important to identify the key effector downstream of the PTEN/PI3K/Akt pathway that drives cancer progression and metastasis. Using the biochemical approaches and mouse genetic models, we identified Skp2 as an important Akt substrate that plays a critical for PTEN/Akt-mediated tumorigenesis. Skp2 (S-phase kinase associated protein-2), an F-box protein, is an E3 ligase component of Skp2 SCF complex responsible for substrate recognition. Skp2 overexpression induces cell cycle entry, and the degradation of p27 is responsible for Skp2-mediated cell cycle progression. Although Skp2 is overexpressed in numerous human cancers and associates with cancer metastasis 1,2, it remains unclear how Skp2 overexpression occurs during cancer progression and how its oncogenic activity is regulated. Our study provides for the first time that Akt kinase phosphorylates Skp2 at S72 and Skp2 S72 phosphorylation is a molecular switch that orchestrates Skp2 E3 ligase activity and oncogenic functions. The objective of this application is to determine the functional crosstalk between PTEN/PI3K/Akt signal and Skp2 S72 phosphorylation in prostate cancer progression and metastasis. The central hypothesis of the application is that Skp2 S72 phosphorylation by PI3K/Akt is critical for prostate cancer progression and metastasis. Our central hypothesis has been formulated on the basis of our strong preliminary data. The rationale of the proposed research is that, once the important role of Skp2 S72 phosphorylation is confirmed and established in prostate cancer progression and metastasis, the better treatment or target for prostate cancer can be achieved. We plan to test our central hypothesis and accomplish the objective of this application by pursuing the following specific aims: Aim 1) To determine the molecular mechanism by which Skp2 gene expression and activity are regulated by the PI3K/Akt pathway. Aim 2) To determine the potential role of Skp2 S72 phosphorylation in prostate cancer progression. Aim 3) To determine the functional crosstalk between Akt and Skp2 in cell migration and invasion. Aim 4) To determine the potential role of Skp2 and Skp2 S72 phosphorylation in prostate cancer metastasis. This proposal work is innovative, because it provides for the first time that Akt is a kinase for Skp2 and that Skp2 S72 phosphorylation by Akt is critical for Skp2 E3 ligase activity, cytosolic localization, and oncogenic functions. Importantly, our study reveals that Skp2 is a critical downstream effector for the PTEN/PI3K/Akt signal in animal models of prostate cancers. With respected outcomes, the combination of work in this proposal is collectively expected to uncover the critical role Skp2 S72 phosphorylation in prostate cancer progression and metastasis. Such results will have an important positive impact and may therefore provide a potentially therapeutic target for prostate cancer treatment. Our results will also fundamentally advance our current understandings of how prostate cancer develops and further progresses into the metastasis stage.
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0.958 |
2014 — 2018 |
Lin, Hui-Kuan |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Novel Posttranslational Modification in Lkb1 Activation and Cancer Development @ Wake Forest University Health Sciences
DESCRIPTION (provided by applicant): Cancer metabolism has recently emerged to play an important role in cancer development and drug resistance. A key regulator involved in cancer metabolism is serine/threonine kinase LKB1. It displays a double-edged sword role in cancer suppression and promotion and forms a heterotrimeric complex with two other proteins, the pseudokinase STRAD and the scaffolding protein MO25. Binding of LKB1 to these two protein promotes and stabilizes the activated conformation of LKB1. Although LKB1 has been shown to play a critical role in regulating cancer development, how LKB1 activation and activity are regulated is poorly defined. Our preliminary results revealed a novel mechanism by which LKB1 kinase activity is maintained. We showed LKB1 kinase activity is positively regulated by oncogenic Skp2, which forms a SCF complex with Skp1, Cul-1 and Rbx1 to constitute an E3 ligase. Interestingly, we found that Skp2 is a direct E3 ligase for LKB1, and Skp2-mediated ubiquitination of LKB1 is required for LKB1 activity. We hypothesized that K63-linked ubiquitination of LKB1 is essential for maintaining the integrity of LKB1-STRAD-MO25 complex, thereby regulating LKB1 activation. The goal of this study is to test this hypothetical model and to determine the role of this ubiquitination in cancer development. We will test our central hypothesis by pursuing three specific aims. Aim 1. To characterize the role of Skp2-mediated K63-linked ubiquitination of LKB1 in LKB1 activity. Rationale. Aim 2. To identify the role of LKB1 in regulating Akt signaling activation. Aim 3. To explore the interplays between Skp2 and LKB1 in oncogenic functions. In summary, our study has several novel discoveries with important clinical implications. First, we showed for the first time that K63-linked ubiquitination of LKB1 i critical for LKB1 kinase activity. Second, we found that LKB1 is required for oncogenic Akt activation in response to EGF, thereby providing an insight and paradigm for oncogenic Akt activation. Third, we showed that Skp2 E3 ligase is an E3 ligase for LKB1, which is critical for LKB1 activation. Fourth, our study may offer a novel insight and mechanism for oncogenic Skp2 in cell transformation and tumorigenesis by activating the LKB1-AMPK-ACC pathway. Finally, our study may not only reveal novel oncogenic function and mechanism for LKB1 in tumor maintenance, but also help identify LKB1-AMPK as potential therapeutic targets for cancer prevention and intervention.
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0.958 |
2015 — 2019 |
Lin, Hui-Kuan |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Identification of a New Strategy For Cancer Therapy @ Wake Forest University Health Sciences
? DESCRIPTION (provided by applicant): PARP-1 inhibitors are recently developed and used to target cancers with a defect in homologous recombination (HR) repair, such as BRCA1 or BRCA2 mutations. However, the usage of the PARP inhibitors is profoundly limited by the fact that BRCA1 or BRCA2 mutations only occur in low percentages of human cancers. Thus, identifying critical regulators that control the HR repair is of significance in further understandng DNA damage response and may provide an important therapeutic target for cancer treatments. In this proposal, we set our goals to identify novel regulators in the HR repair pathway that can serve as druggable targets and be used as potential targets in combination with PARP inhibitor to trigger synthetic lethality in cancers. Our study provides the convincing evidence that Skp2 E3 ligase is a novel regulator critical for ATM activation and HR repair, revealing an insight into how DNA damage response is regulated and further providing a new paradigm for a synthetic lethal strategy for cancers. The objectives of this proposal are to determine how Skp2 is recruited to DNA damage foci to regulate ATM activation, how Skp2-medaited NBS1 ubiquitination regulates HR repair and to identify a novel therapeutic strategy for cancer treatment. We will pursue our goals by performing the following specific aims. Aim 1) Understanding the novel regulation of Skp2 E3 ligase in HR repair and genomic instability. Aim 2) To determine the role of K63-linked ubiquitination in the component of the MRN complex in telomere maintenance and DNA damage repair. Aim 3. Understanding novel mechanisms by which Skp2 regulates kinase signaling and tumorigenesis for cancer therapy. In sum, our study provides molecular insights into how MRN complex regulates ATM activation. We show that Skp2 E3 ligase is a critical regulator required for the recruitment of ATM to DNA damage foci and subsequent ATM activation. So far, all Skp2 substrates identified in the last decade are known to undergo ubiquitin- dependent proteasome degradation. However, in this study we identify for the first time a novel non-proteolytic function for Skp2 in DNA damage response. Skp2 triggers non-proteolytic K63-linked ubiquitination of NBS1 and facilitates activation and recruitment of ATM to DNA damage foci. Moreover, we have developed for the first time specific Skp2 inhibitors that can be used for cancer targeting. Our study provides convincing evidence that Skp2 E3 ligase is a novel regulator critical for ATM activation and HR repair, shedding new lights on how DNA damage response is regulated and further offering a new paradigm for a synthetic lethal strategy for cancer treatments.
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0.958 |
2019 — 2021 |
Lin, Hui-Kuan |
P30Activity Code Description: To support shared resources and facilities for categorical research by a number of investigators from different disciplines who provide a multidisciplinary approach to a joint research effort or from the same discipline who focus on a common research problem. The core grant is integrated with the center's component projects or program projects, though funded independently from them. This support, by providing more accessible resources, is expected to assure a greater productivity than from the separate projects and program projects. |
Signaling and Biotechology Program @ Wake Forest University Health Sciences |
0.942 |
2021 |
Lin, Hui-Kuan |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Regulation of Oncogenic Akt Ubiquitination and Activation by Diverse Mechanisms in Cancer @ Wake Forest University Health Sciences
Summary The PI3K/Akt signaling is one of most important oncogenic events in human cancers. It regulates many aspects of biological functions including cell proliferation, survival, and metabolism important for cancer initiation and progression. While extensive efforts have been made in the last three decades to understand the downstream effectors responsible for the biological and oncogenic processes regulated by PI3K/Akt signaling, the upstream signals mediating PI3K/Akt signaling activation upon diverse growth factor stimulation is not well understood. Understanding and defining the upstream mechanisms responsible for PI3K/Akt signaling activation will not only provide new insight into how PI3K/Akt signaling activation is orchestrated, but also offer novel paradigms and therapeutic targets for cancer intervention. Although it has been well established that PIP3 is critical for the membrane recruitment and subsequent activation of Akt, our recent studies provide the evidence that Akt undergoes methylation and subsequent non-proteolytic K63-linked ubiquitination, which are crucial for Akt membrane recruitment and subsequent phosphorylation and activation upon stimulation with diverse growth factors, opening up a new frontier for Akt signaling regulation. Of note, we identified SETDB1 as a methyltransferase for Akt K64 methylation and TRAF6 ligase as an upstream E3 ligase triggering K63-linked ubiquitination and activation of Akt, and these events are required for cancer progression. However, the outstanding questions remained to be addressed are how SETDB1 and TRAF6 are activated or recruited to the Akt complex upon growth factor treatment to trigger Akt methylation and subsequent Akt ubiquitination and activation, thus promoting oncogenic processes. The goal of this study is to dissect the upstream regulatory mechanisms by which growth factors activate and recruit SETDB1 and TRAF6 ligase to Akt complex to elicit Akt methylation and subsequent Akt ubiquitination, define the mechanism by which Akt ubiquitination facilitates Akt membrane localization and activation, and finally explore the role of these regulatory modes in cancer development and develop small molecule inhibitors targeting these regulatory mechanisms. Our preliminary results revealed that SETDB1 and TRAF6 undergo novel posttranslational modifications, which are crucial for methylation, ubiquitination and activation of Akt by growth factors and oncogenic activity. We hypothesized that SETDB1 and TRAF6 undergo the novel posttranslational modification upon growth factor treatment, which recruits SETDB1 to the Akt complex and activates TRAF6 E3 ligase to facilitate Akt methylation and subsequent Akt ubiquitination and activation, thus leading to tumorigenesis. Our innovative hypothesis has been formulated based on our preliminary results and prior research. We proposed three specific aims to validate this provocative and paradigm-shifting concept using cutting-edge technologies including xenograft, organoids from genetic mouse tumor models and patient derived tumors, patient-derived models (PDX), knockin mouse models, genetic mouse tumor models and pharmacological approaches. This application is significant, therefore, because it is expected to provide the knowledge needed to develop pharmacologic strategies that will allow concurring cancers with aberrant PI3K/Akt activation. Our study will open up a new avenue for PI3K/Akt signaling regulation, but also offer new concepts and strategies for cancer targeting.
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0.942 |