Melanoma, one of the most notorious and lethal forms of skin cancer, remains resistant to available treatments. Therefore, novel target-based approaches are needed for the management of this neoplasm. An in-depth knowledge of the genetic controls of cellular proliferation and cell division may provide critical information regarding melanomagenesis. Polo-like kinase 1 (Plk1), a member of highly conserved family of mitotic serine/threonine kinases, plays a critical role in cell division and cycle progression. Plk1 dysregulation has been shown to result in chromosomal instability, aneuploidy and tumor development. However, the functional role of Plk1 in melanoma development is not well understood. In a recent study, we demonstrated that i) Plk1 was over-expressed in both clinical melanoma specimens and cultured human melanoma cells when compared to normal skin and cultured normal melanocytes, respectively;and ii) inhibition of Plk1 resulted in a significant decrease in the viability and growth of melanoma cells. This study suggested that Plk1 may have an important role in melanoma. However, additional studies are needed to assess the functional significance of Plk1 in melanoma and to define its molecular mechanism(s). Our preliminary data have shown that i) Plk1 binds with endogenous Numb (antagonist of Notch and a p53 regulator) both in vitro and in vivo, ii) localization of Plk1 and Numb are reliant upon the expression of each other, and iii) loss of either Plk1 or Numb expression results in a similar cell cycle profile with a G2/M cell cycle arrest. Based on our published study and our preliminary data, we propose to test the hypothesis that Plk1 and Numb work in close concert during mitosis, expression of both are required for proper melanocytic cell division and integrity, and loss of Numb and Plk1 regulation deregulates p53 contributing to increased genomic instability and melanomagenesis. We will challenge this hypothesis in three specific aims. . First, employing retrospective surgical specimens, we will determine the stage-specific association between Plk1, p53 and Numb during melanoma progression. We will employ quantitative AQUA analysis in tissues of different stages during melanomagenesis (common and dysplastic nevi, localized cutaneous melanoma, and melanoma with regional lymph node involvement). Next, in order to define the cooperation between Plk1 and Numb, we will determine the consequence of shRNA mediated knockdown of Plk1 and Numb on one another by assessing the effects on mRNA and protein expression, stability, and localization, as well as mitotic structures in melanoma cells and normal melanocytes. Further, extensive experiments will be conducted to dissect the mechanistic details of the Plk1 and Numb interaction. Finally, we will determine the in vivo relevance of our in vitro findings by determining the consequence of Plk1 and Numb inhibition in athymic nude mice xenografts implanted with melanoma cells with varying Plk1 and Numb expression. Outcome of proposed studies may define the role and cooperation of Plk1and Numb in melanomagenesis. Further, the work proposed in this application is relevant to military Veterans as melanoma incidence is higher in veteran population. Our proposed study may lead to identification of novel strategies for the management of this deadly neoplasm.
Melanoma, one of the most notorious and lethal forms of skin cancer, remains resistant to available treatments. Therefore, novel target-based approaches are needed to manage this cancer. Understanding the mechanisms of melanoma development and growth is a continuing challenge. We have recently demonstrated that Plk1, a gene involved in cell division, may have an important role in melanoma. Here, we propose to conduct pre-clinical studies (in cell culture and animal model) to access if and how Plk1 cooperates with another gene 'Numb'in melanoma development and growth. We will also ascertain this proposed cooperation between these two regulators using clinical melanoma samples. Finally, we will ascertain the therapeutic relevance of Plk1 and Numb in vivo in a mouse model. We believe that the outcomes of this study will we useful in understanding the mechanism of melanoma and in identifying novel targets for melanoma management.
| Singh, Chandra K; Chhabra, Gagan; Ndiaye, Mary Ann et al. (2018) The Role of Sirtuins in Antioxidant and Redox Signaling. Antioxid Redox Signal 28:643-661 |
| Chhabra, Gagan; Singh, Chandra K; Ndiaye, Mary Ann et al. (2018) Prostate cancer chemoprevention by natural agents: Clinical evidence and potential implications. Cancer Lett 422:9-18 |
| Wilking-Busch, Melissa J; Ndiaye, Mary A; Liu, Xiaoqi et al. (2018) RNA interference-mediated knockdown of SIRT1 and/or SIRT2 in melanoma: Identification of downstream targets by large-scale proteomics analysis. J Proteomics 170:99-109 |
| Garcia-Peterson, Liz Mariely; Ndiaye, Mary Ann; Singh, Chandra K et al. (2017) SIRT6 histone deacetylase functions as a potential oncogene in human melanoma. Genes Cancer 8:701-712 |
| Gutteridge, Rosie Elizabeth Ann; Singh, Chandra K; Ndiaye, Mary Ann et al. (2017) Targeted knockdown of polo-like kinase 1 alters metabolic regulation in melanoma. Cancer Lett 394:13-21 |
| Cholewa, Brian D; Ndiaye, Mary A; Huang, Wei et al. (2017) Small molecule inhibition of polo-like kinase 1 by volasertib (BI 6727) causes significant melanoma growth delay and regression in vivo. Cancer Lett 385:179-187 |
| Chhabra, Gagan; Ndiaye, Mary Ann; Garcia-Peterson, Liz Mariely et al. (2017) Melanoma Chemoprevention: Current Status and Future Prospects. Photochem Photobiol 93:975-989 |
| Garcia-Peterson, Liz Mariely; Wilking-Busch, Melissa Jean; Ndiaye, Mary Ann et al. (2017) Sirtuins in Skin and Skin Cancers. Skin Pharmacol Physiol 30:216-224 |
| Singh, Chandra K; Malas, Kareem M; Tydrick, Caitlin et al. (2016) Analysis of Zinc-Exporters Expression in Prostate Cancer. Sci Rep 6:36772 |
| Gutteridge, Rosie Elizabeth Ann; Ndiaye, Mary Ann; Liu, Xiaoqi et al. (2016) Plk1 Inhibitors in Cancer Therapy: From Laboratory to Clinics. Mol Cancer Ther 15:1427-35 |
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