Project Details


Description (Abstract): The long-term goal of this proposal is to elucidate the
mechanisms of hematopoietic disruption caused by breast cancer (BC) metastasis
to the bone marrow (BM), their preferred homing site. Despite "successful"
treatments, BM involvement is common. BC metastasis to the BM is associated
with poor prognosis. We arbitrarily assign BC metastasis as two stages, early
and late. Early being at a time long before the primary tumor is detectable and
late being the time when the cancer cells disrupt the BM. This study will focus
on early metastasis since understanding early interactions among BC and BM
cells will allow preventive and/or novel therapeutic targets. We hypothesize
that preprotachykinin-I (PPT-I) and the genes for its receptors, neurokinin
(NK)-1 and NK-2, over expressed in BC cells, are important mediators in the
early integration of BC cells within BM stromal cells. Preliminary studies from
our lab support this hypothesis. Four specific aims will test this hypothesis.
We will use an in vitro co-culture model with BC and BM stromal cells to study
their interactions. For this proposed period, we will use twelve defined
malignant cell lines and four normal mammary epithelial cell lines. Preliminary
studies show that the latter do not integrate and survive among BM stroma. Aim
I will expand on preliminary studies to understand early integration between BC
and BM stromal cells using the in vitro co-cultures. We will determine the type
of BC-stromal interactions (direct vs. indirect) and determine the relationship
between expression of PPT-I, NK-1, and NK-2, and co-culture confluence.
Preliminary studies indicate changes in specific gone expression in both the BC
and BM stromal cells during co-culture. Furthermore, although the preliminary
studies show that PPT-I are involved in the integration of BC cells to the BM,
the evidence indicate that it interacts with other factors. To this end, aim 2
will take advantage of vast numbers of commercial DNA arrays to analyze
differences in various categories of genes in BC and stromal cells during
different levels of confluence. Aim 3 will study the role of PPT-I in more
detail. In the first set of experiments, we will transiently knockout PPT-I
with antisense to beta-PPT-I and then study they ability integrate within BM
stromal cells. Since multiple genes are dysregulated in cancer cells, the
second set of experiments will use a more defined model to study the role of
PPT-I. We will use normal mammary epithelial, stably transfected with PPT-I
and/or NK-1 expression vectors. Initial experiments will be qualitative with
the genes under the control of relatively strong (RSV) and weak (CMV)
promoters. The results of these experiments will direct studies with PPT-I
quantitatively expressed with the Tet-off system. Since BC metastasis involves
two major cell subsets, mesenchymal (stroma) and epithelial (BC), aim 4 will
determine if regulation of PPT-I, NK-1 and NK-2 is tissue specific by studying
their promoters in these cell subsets.
Effective start/end date7/1/006/30/05


  • National Cancer Institute: $211,950.00
  • National Cancer Institute: $211,950.00
  • National Cancer Institute: $211,950.00
  • National Cancer Institute: $237,266.00


  • Oncology
  • Cancer Research


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