Elucidating Clonal Competition Through Fluorescent Color Coding of Melanoma Cells
Abstract
This is an application for the Fiscal Year 2016 Peer Reviewed Cancer Research Program “Melanoma and other skin cancers” Topic Area with a Military Relevance Focus Area on closing the gap in cancer treatment. Skin cancer remains a serious disease burden worldwide. The World Health Organization (WHO) estimates that 1 in 3 cancers diagnosed in the world is a skin cancer. About 3 million non-melanoma skin cancers and 132,000 cutaneous melanomas occur globally every year. In the United States, 1 in 5 Americans are expected to develop some form of skin cancer. Skin malignancies are also common in the military population. For at least the past 15 years, melanoma and other skin cancers are recorded to be the most common cancer group among military personnel. Moreover, studies of Soldiers from World War II showed a 3-fold greater risk of melanoma among Pacific prisoners-of-war (POWs) compared to their European counterparts. In addition, Pacific and European POWs experience 3.4-fold and 2.8-fold more deaths from melanoma, respectively, compared to matched white U.S. men in the general population. Skin cancer treatment in the Department of Veterans Affairs (VA) system has been estimated to exceed $100 million per year not accounting for metastatic disease developing from melanomas. Tumor evolution fundamentally reflects the expansion and contraction of composite clones as a result of genetic heterogeneity, microenvironmental stress, drug selection, and immune editing. A driving force behind clonal dynamics is intratumoral competition, which facilitates the “stratification” of clones into “winners” and “losers.” Recently, studies have successfully employed next-generation sequencing and genetic barcoding to study clonal dynamics either as xenografts or in the context of drug resistance. However, the allure of DNA tracing is also limited by (a) its inherently destructive modality, (b) its sequence, rather than cell-based, unit of count, (c) the risk of endogenous mutagenesis and misclassification, (d) possible technical infidelity, and (e) burdensome costs. We have developed a more nimble, less complex and cell-focused tracing method via massively parallel fluorescent protein coding of cells. Early pilot analyses indicate that clonal competition is rapid, reproducible, and self-organizing. The ability to observe cellular competition underpins the strategy for elucidating clonal dynamics in this proposal. In Aim 1, we will attempt to understand the hierarchy of clonal stratification. We hypothesize that there must be a self-organizing, rather than stochastic, structure that determines outcome (i.e., “winner” vs. “loser”). In Aim 2, we will define the molecular basis of clonal stratification both in vitro and in vivo. Since stratification occurs over a timeframe that is much too short for mutagenesis, we hypothesize that clonal competition reflects utilization of dominating drivers and pathways. Finally, in Aim 3, we will determine the role of inter-clonal competition in therapeutic resistance. We propose that during the acquisition of therapeutic resistance, the rules of competition between clones are modified by innate and secondary resistance pathways. Clonal dynamics has been a cornerstone of the tumor evolution theory and competition represents a critical dimension of cellular dynamics, which has only been inferred through current sequencing technologies. The proposed studies will afford us a front-row view of clonal competition through massively parallel color coding.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1710501
Entities
People
- Hensin Tsao
Organizations
- Massachusetts General Hospital
- United States Army