Follicular lymphoma (FL) is generally an incurable disease. In each case the tumor is composed of a clonal population of B cells with a unique B cell antigen receptor (BCR). We have recently discovered that at the time of diagnosis, each FL tumor contains a subpopulation of tumor cells that has defective signaling through its B cell antigen receptor (1). The size of this BCR insensitive tumor subpopulation expands over time, and it predicts poor response to chemotherapy and a shorter overall survival. Thus, we pose the question "what is the relationship between the two subpopulations of tumor cells in follicular lymphoma- the BCR sensitive and the BCR insensitive?" We postulate several models:1. The BCR insensitive population arises from the BCR sensitive population, 2. Each of the two tumor subpopulations arises from a common but rare tumor-initiating cell, or 3. The BCR insensitive population is the more primitive cell that initially gives rise to the dominant BCR sensitive population but eventually dominates due to negative selective forces of antigenic stimulation or differential sensitivity to therapy. We will distinguish between these hypotheses by separating the two subpopulations of tumor cells from individual cases and by performing comparative genetic analyses on the respective pairs. We will clone and sequence the VDJ region genes from each subpopulation and examine their patterns of V region somatic mutations. By comparing their respective evolutionary paths we will infer the clonal relationships between the BCR sensitive and BCR insensitive subpopulations. In a second approach we will compare the global patterns of DNA gains and losses between the two tumor subpopulations and identify the changes unique to each. All tumor cells should share the driver DNA gains and losses with the progenitor tumor cell;additional gains and losses should reveal how the two subpopulations evolved in relation to each other. Finally, we will search for the root cause of BCR insensitivity in each case. Using next generation DNA sequencing technology, we will conduct large scale deep resequencing of genes of the BCR signaling pathway. We expect to find mutations in the proximal members of the pathway. In order to discover other differences between BCR sensitive and BCR insensitive tumor cell subsets we will compare their gene expression profiles.

Public Health Relevance

The knowledge gained in this project may lead to new therapies for follicular lymphoma based on targeting a BCR insensitive tumor subpopulation that we have recently discovered. This tumor subpopulation expands over time and is correlated with response to chemotherapy and decreased overall survival of the patients.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA151748-02
Application #
8232070
Study Section
Cancer Genetics Study Section (CG)
Program Officer
Howcroft, Thomas K
Project Start
2011-04-01
Project End
2016-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
2
Fiscal Year
2012
Total Cost
$490,247
Indirect Cost
$179,964
Name
Stanford University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Kohrt, Holbrook E; Thielens, Ariane; Marabelle, Aurelien et al. (2014) Anti-KIR antibody enhancement of anti-lymphoma activity of natural killer cells as monotherapy and in combination with anti-CD20 antibodies. Blood 123:678-86
Green, Michael R; Gentles, Andrew J; Nair, Ramesh V et al. (2013) Hierarchy in somatic mutations arising during genomic evolution and progression of follicular lymphoma. Blood 121:1604-11