With an estimated 37 680 new diagnoses and 34 290 deaths in
2008, cancer of the pancreas is the eleventh most common
cancer in the United States and fourth in fatalities.
American centres treat resectable pancreatic cancer with resec-
tion followed by adjuvant chemoradiation, which extends sur-
vival from 12 months with surgery alone to about 20 months
with adjuvant chemoradiation, with a 20% 5 year post-operative
survival. Conversely, the neoadjuvant approach, with assured
administration of chemoradiation to all potential surgical
candidates and potentially improved patient tolerance prior
to surgery, offers some theoretical advantages over immediate
surgery. Pre-operative treatment may decrease tumour size and
increase the chances of an R0 (microscopically negative margin)
resection. However, about 30% of patients treated with pre-
operative chemoradiation will develop progressive disease and
will never come to surgery. Clearly, discovery of a means to
predict the outcome with the adjuvant or neoadjuvant approach
would be extremely useful.
Gemcitabine (GEM) is the standard chemotherapy for
pancreatic cancer. GEM interferes with DNA replication and
prevents the proofreading enzymes from detecting, excising and
repairing the DNA.
In vitro studies have shown that cells deﬁ-
cient in DNA mismatch repair (MMR) enzymes are more sen-
sitive to GEM/radiation.
The RecQ family is a highly conserved
group of DNA helicases required for the maintenance of genome
stability and integrity. They have an important role in DNA
replication, telomere maintenance, DNA damage signalling and
DNA repair pathways including mismatch repair, nucleotide
excision repair and direct repair.
The most highly expressed
but smallest member of this family in human cells is the RecQ
protein-like (DNA helicase Q1-like) (RECQL often named
RECQ1). RECQL catalytic activities include the DNA unwinding
of diverse but speciﬁc DNA structures, the annealing of comple-
mentary single-stranded DNA and DNA branch migration.
This protein plays an important role in chromosomal stability
and genome maintenance.
It interacts with and binds to mis-
match repair proteins that regulate genetic recombination
participates in the repair of endogenous or exogenously induced
RECQL is highly expressed in rapidly proli-
ferating cancer cells and transformed cells and provides these
cells with a growth advantage
suggesting that greater copy
numbers of RECQL may be needed to repair the elevated load
of endogenous DNA damage generated during their accelerated
cell cycle. Accordingly, RECQL acute depletion (silencing by
small interference RNA) in cancer cells induces growth retar-
dation, sensitivity to DNA damaging agents, accumulation of
DNA damage, chromosomal instability and ultimately results
in mitotic catastrophe coupled with mitotic cell death in cancer
cells already compromised in their checkpoint.
allelic loss at the RECQL locus (chromosome 12p12) is frequent
in different tumour types.
Alteration in DNA repair pathways may affect the cytotoxicity
of chemotherapy and radiotherapy, more speciﬁcally the resis-
tance to gemcitabine-induced DNA replication arrest and the
repair of DNA double-strand breaks caused by radiation. The
importance of RECQL in damage repair is further supported
by the observation that a single nucleotide polymorphism (SNP)
located in the 3′ untranslated region (UTR) (A159C) negatively
affects the overall survival and response to gemcitabine-induced
radiosensitization of patients diagnosed with pancreatic adeno-
carcinoma treated with neoadjuvant chemoradiation.
SNP exerts its effect in a dominant-inheritance mode.
Genetic changes can be considered either germline or somatic.
Germline variation refers to an alteration in DNA sequence inher-
ited from one’s parents. Single nucleotide polymorphisms (SNPs)
account for more than 90% of germline variation in the human
genome, and have been implicated in phenotype, disease predis-
position and response to therapy.
Somatic mutations, to the
contrary, are found in diseased tissue (i.e. tumour) only, and
are not a part of the inherited genetic complement. By altering
protein function, somatic mutations can have a profound impact
on tumour development and proliferation (e.g. tumour sup-
pressor genes and oncogenes).
In the present study, the RECQL gene was sequenced in patients
with pancreatic cancer to discover the presence of additional SNPs
or mutations in the coding region that may directly affect the
function of the gene. In addition, to evaluate the prognostic value
of the 3′UTR A159C SNP in association with the course of treat-
ment, the effect of the SNP on clinical outcome was compared
in two cohorts of patients with resectable pancreatic cancer:
one treated with resection and adjuvant chemoradiation, and the
other treated with neoadjuvant chemoradiation with surgery or
additional chemotherapy as indicated by repeat CT scan.
Material and methods
Sample collection and processing
Informed consent from patients with resectable pancreatic exo-
crine adenocarcinoma was obtained under an institutional review
board approved protocol at the institutions participating in this
study (BCM: H16215 issued 9/22/04; TJU: 06U.76 issued 4/27/06;
MDA: ID 98–155 issued 09/09/98). A total of 53 patients with
exocrine adenocarcinoma located in the head of the pancreas were
treated with pancreaticoduodenectomy (Whipple procedure) and
adjuvant chemoradiation at the Elkins Pancreas Center at Baylor
College of Medicine (BCM), Houston, and the Thomas Jefferson
University Center (TJU) for Pancreatic, Biliary and Related
Cancers, Philadelphia (26 and 27 patients, respectively). One
hundred twenty-three patients received neoadjuvant chemora-
diation at the University of Texas MD Anderson Cancer Center
The blood from the BCM patients was directly collected in
PAXgene Blood DNA tubes, and the DNA was isolated with the
PAXgene Blood DNA kit (PreAnalytiX; Qiagen, Valencia, CA,
USA) according to the manufacturer’s instructions. The MDACC
HPB 2009, 11, 435–444 © 2009 International Hepato-Pancreato-Biliary Association