Significant disparity in the incidence and clinical outcome of prostate cancer (PCa) exist between African- American (AA) men and their European American (EA) counterparts. Despite this recognition, we have not made a major leap in our understanding of the molecular causes associated with such disparity. This proposal is built upon our strong preliminary data on a proto-oncogene, Myb, which has remained largely unexplored in PCa. Our novel findings demonstrate that 1) Myb expression is significantly elevated in AA PCa with greater overall incidence as compared to EA PCa, 2) low intensity expression of Myb is also detected in some of the benign prostate tissues (BPH) from AA patients, while no expression is detected in EA BPH, 3) AA PCa cell lines (MDaPCa-2b and RC-77/T) exhibit high Myb expression and significant resistance to hormone-depletion and docetaxel (DTX) toxicity, 4) AA PCa cells also display high growth, migratory and invasive potential, which is associated with Myb overexpression, and 5) Myb interacts with AR and modulates the expression of androgen-responsive gene, KLK3/PSA, suggesting their cooperative role in gene regulation. Based on these promising findings, we hypothesize that relative greater incidence and overall expression of Myb in AA PCa cells underlies their inherently greater propensity to metastasize and evade therapeutic intervention. To test this hypothesis, we are proposing three specific aims.
In aim 1, we will investigate the role of Myb in PCa aggressiveness and therapy-resistance. Using luciferase-tagged, Myb-overexpressing or -silenced, paired AA and EA PCa cell lines, we will examine the functional association of Myb with PCa growth and metastasis, and their response to castration- and docetaxel- therapies in an orthotopic mouse model.
In Aim 2, we will examine the functional consequences of Myb-AR interaction and identify their downstream consequences. We will specifically examine whether Myb has a role in AR localization and transcriptional activation. Furthermore, we will assess the effect of Myb on transcriptional reprogramming of AR by using state of the art RNA-Seq and ChIP-Seq approaches. We will determine the shared and independent targets of Myb and AR in PCa cells and examine if Myb alters AR target gene specificity.
In Aim 3, we will determine the clinical relevance of Myb in racial disparity associated with PCa. We will perform immunohistochemical (IHC) analysis to assess Myb and AR expression and localization (cytoplasmic vs. nuclear) in PCa, adjacent BPH, and uninvolved normal tissues from both AA and EA cases. We will then examine their correlation (alone and in combination) with race, tumor grade, metastasis incidence, PSA levels, and patient's survival. Together, these studies will provide experimental, mechanistic and clinical evidence for the role of Myb in aggressive behavior and therapeutic- resistance of PCa, and support the association of Myb with observed racial disparity. In the long-term, the resulting information will be useful in reducing the racial disparities in clinical outcomes of PCa by establishing the clinical utility of Myb as a risk predictor and/or therapeutic target for effective disease management.

Public Health Relevance

Main barrier in achieving progress toward racial disparities reduction in prostate cancer is our limited understanding of the underlying molecular basis. The proposed research will examine the functional and clinical significance of Myb overexpression in prostate cancer aggressiveness and therapeutic resistance, the two major reasons for the poor clinical outcome of African American (AA) patients. The outcomes of our study will allow distinction between clinically indolent and aggressive prostate tumors, and pave the way for novel target-based therapies, which will ultimately reduce the enhanced burden of prostate cancer on African American population and improve overall survival of prostate cancer patients.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project--Cooperative Agreements (U01)
Project #
1U01CA185490-01
Application #
8687364
Study Section
Special Emphasis Panel (ZRG1-OBT-Z (55))
Program Officer
Woodhouse, Elizabeth
Project Start
2014-05-09
Project End
2019-04-30
Budget Start
2014-05-09
Budget End
2015-04-30
Support Year
1
Fiscal Year
2014
Total Cost
$313,325
Indirect Cost
$105,825
Name
University of South Alabama
Department
Type
Schools of Medicine
DUNS #
172750234
City
Mobile
State
AL
Country
United States
Zip Code
36688
Srivastava, Sanjeev K; Ahmad, Aamir; Zubair, Haseeb et al. (2017) MicroRNAs in gynecological cancers: Small molecules with big implications. Cancer Lett 407:123-138
Zubair, Haseeb; Bhardwaj, Arun; Ahmad, Aamir et al. (2017) Hydroxytyrosol Induces Apoptosis and Cell Cycle Arrest and Suppresses Multiple Oncogenic Signaling Pathways in Prostate Cancer Cells. Nutr Cancer 69:932-942
Srivastava, Sanjeev K; Ahmad, Aamir; Miree, Orlandric et al. (2017) Racial health disparities in ovarian cancer: not just black and white. J Ovarian Res 10:58
Zubair, Haseeb; Azim, Shafquat; Ahmad, Aamir et al. (2017) Cancer Chemoprevention by Phytochemicals: Nature's Healing Touch. Molecules 22:
Bhardwaj, Arun; Srivastava, Sanjeev K; Khan, Mohammad Aslam et al. (2017) Racial disparities in prostate cancer: a molecular perspective. Front Biosci (Landmark Ed) 22:772-782
Khushman, Moh'd; Bhardwaj, Arun; Patel, Girijesh Kumar et al. (2017) Exosomal Markers (CD63 and CD9) Expression Pattern Using Immunohistochemistry in Resected Malignant and Nonmalignant Pancreatic Specimens. Pancreas 46:782-788
Patel, Girijesh Kumar; Khan, Mohammad Aslam; Bhardwaj, Arun et al. (2017) Exosomes confer chemoresistance to pancreatic cancer cells by promoting ROS detoxification and miR-155-mediated suppression of key gemcitabine-metabolising enzyme, DCK. Br J Cancer 116:609-619
Deshmukh, Sachin K; Azim, Shafquat; Ahmad, Aamir et al. (2017) Biological basis of cancer health disparities: resources and challenges for research. Am J Cancer Res 7:1-12
Deshmukh, Sachin K; Srivastava, Sanjeev K; Zubair, Haseeb et al. (2017) Resistin potentiates chemoresistance and stemness of breast cancer cells: Implications for racially disparate therapeutic outcomes. Cancer Lett 396:21-29
Zubair, Haseeb; Azim, Shafquat; Khan, Husain Yar et al. (2016) Mobilization of Intracellular Copper by Gossypol and Apogossypolone Leads to Reactive Oxygen Species-Mediated Cell Death: Putative Anticancer Mechanism. Int J Mol Sci 17:

Showing the most recent 10 out of 26 publications