| Bronchioalveolar
carcinoma (BAC) is a subset of lung adenocarcinoma
with unique biology in that it more often occurs
in young, female and non-smoking patients than
other types of lung cancer. BAC has a histologic
spectrum from pure BAC (PBAC) to BAC with focal
invasion (BWFI) and adenocarcinoma with BAC features
(AWBF). The epidermal growth factor receptor (EGFR)
is over-expressed or mutated in most cases of
lung cancer including BAC. The EGFR plays a pivotal
role in lung cancer development and progression,
influencing cell proliferation, regulation of
apoptotic cell death, angiogenesis and metastasis.
This growth factor signaling pathway is the target
of small molecule tyrosine kinase inhibitors (TKI)
erlotinib and gefitinib. In addition to EGFR,
other genes are aberrantly expressed in lung adenocarcinomas.
Our recent analysis indicates that 16 of 19 (84%)
lung adenocarcinoma cell lines have reduced or
lost HSulf-1 expression, including complete loss
in two of two BAC cell lines. HSulf-1 expression
is silenced by promoter methylation and histone
deacetylation as treatment of H358 and H650 BAC
cell lines with 5-aza-cytidine and LBH-598 (Novartis)
resulted in re-induction of HSulf-1 transcription.
HSulf1 is an arylsulfatase that selectively removes
the 6-O-sulfate from heparan sulfate proteoglycans.
Loss of HSulf-1 results in increased signaling
by heparin-binding growth factors (HB-GF) such
as heparin-binding epidermal growth factor (HB-EGF).
In addition to modulating EGFR signaling, HSulf-1
modulates signaling by other HB-GFs such as Fibroblast
Growth Factor, Hepatocyte Growth Factor (HGF)
and Vascular Endothelial Growth Factor-A, thereby
attenuating downstream Erk activation. In vitro,
HSulf-1 transfected cells proliferate slower and
are more sensitive to cisplatin and taxol than
their HSulf-1-deficient counterparts in ovarian,
breast and hepatocellular cell lines. Our data
in squamous cell carcinoma of the head and neck
indicated that loss of HSulf-1 is also involved
in promoting HGF-mediated invasion and migration
of cancer cells. Thus, HSulf-1 could be a marker
of risk for developing other BAC nodules in the
same or the contra-lateral lung. Furthermore,
modulation of EGFR signaling by HSulf-1 may render
these tumors sensitive to EGFR inhibition. In
a recent study it was reported that only 23% of
the patients with BAC responded to erlotinib.
High level of phosphorylated Mitogen-Activated
Protein Kinase (MAPK), part of the MAPK/Erk pathway,
was the only parameter that was predictive of
poor survival. The main objectives of this proposal
are to 1) Determine the mechanism of loss of HSulf-1
in 150 primary BACs consisting of a) 50 PBAC,
b) 50 BWFI and c) 50 AWBF, 2) Determine whether
HSulf-1 expression correlates with clinical behavior
of BACs in these 150 tumors. HSulf-1 expression
will also be correlated with sulfation state of
HSPGs with 10E4 staining, a sulfation specific
anti HSPG antibody, 3) Determine whether HSulf-1
expression is a predictive marker for TKI response.
Using BAC cell lines with and without HSulf-1
expression, we will determine whether a) the presence
of HSulf-1 confers sensitivity to cisplatin and
taxol induced cytotoxicity b) Evaluate the cytotoxicity
of TKI as single agents when applied to parental
vs. HSulf-1 transfected clones in vitro. C) Evaluate
the effects of TKIs in combination with cisplatin,
paclitaxel, topotecan and gemcitabine in vitro.
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