Molecular mechanisms of pancreatic carcinogenesis
Pancreatic ductal adenocarcinoma is one of the most fatal malignancies. Intensive investigation of molecular pathogenesis might lead to identifying useful molecules for diagnosis and treatment of the disease. Pancreatic ductal adenocarcinoma harbors complicated aberrations of alleles including losses of 1p, 6q, 9p, 12q, 17p, 18q, and 21q, and gains of 8q and 20q. Pancreatic cancer is usually initiated by mutation of KRAS and aberrant expression of SHH. Overexpression of AURKA mapping on 20q13.2 may significantly enhance overt tumorigenesity. Aberrations of tumor suppressor genes synergistically accelerate progression of the carcinogenic pathway through pancreatic intraepithelial neoplasia (PanIN) to invasive ductal adenocarcinoma. Abrogation of CDKN2A occurs in low-grade/early PanIN, whereas aberrations of TP53 and SMAD4 occur in high-grade/late PanIN. SMAD4 may play suppressive roles in tumorigenesis by inhibition of angiogenesis. Loss of 18q precedes SMAD4 inactivation, and restoration of chromosome 18 in pancreatic cancer cells results in tumor suppressive phenotypes regardless of SMAD4 status, indicating the possible existence of a tumor suppressor gene(s) other than SMAD4 on 18q. DUSP6 at 12q21-q22 is frequently abrogated by loss of expression in invasive ductal adenocarcinomas despite fairly preserved expression in PanIN, which suggests that DUSP6 works as a tumor suppressor in pancreatic carcinogenesis. Restoration of chromosome 12 also suppresses growths of pancreatic cancer cells despite the recovery of expression of DUSP6; the existence of yet another tumor suppressor gene on 12q is strongly suggested. Understanding the molecular mechanisms of pancreatic carcinogenesis will likely provide novel clues for preventing, detecting, and ultimately curing this life-threatening disease.
doi: 10.1111/j.1349-7006.2006.00134.x Cancer Sci | January 2006 | vol. 97 | no. 1 | 1–7
© 2006 Japanese Cancer Association
Blackwell Publishing Asia
Molecular mechanisms of pancreatic carcinogenesis
and Akira Horii
Departments of Molecular Pathology and
Gastroenterological Surgery, Tohoku University School of Medicine, 2-1 Seiryo-machi,
Aoba-ku, Sendai 980-8575, Japan
(Received July 3, 2005/Revised 14 October, 2005/Accepted October 18, 2005/Online publication December 2, 2005)
Pancreatic ductal adenocarcinoma is one of the most fatal
malignancies. Intensive investigation of molecular pathogenesis
might lead to identifying useful molecules for diagnosis and
treatment of the disease. Pancreatic ductal adenocarcinoma
harbors complicated aberrations of alleles including losses of 1p,
6q, 9p, 12q, 17p, 18q, and 21q, and gains of 8q and 20q. Pancreatic
cancer is usually initiated by mutation of KRAS and aberrant
expression of SHH. Overexpression of AURKA mapping on 20q13.2
may significantly enhance overt tumorigenesity. Aberrations of
tumor suppressor genes synergistically accelerate progression of
the carcinogenic pathway through pancreatic intraepithelial
neoplasia (PanIN) to invasive ductal adenocarcinoma. Abrogation
of CDKN2A occurs in low-grade/early PanIN, whereas aberrations
of TP53 and SMAD4 occur in high-grade/late PanIN. SMAD4 may
play suppressive roles in tumorigenesis by inhibition of angio-
genesis. Loss of 18q precedes SMAD4 inactivation, and restoration
of chromosome 18 in pancreatic cancer cells results in tumor
suppressive phenotypes regardless of SMAD4 status, indicating
the possible existence of a tumor suppressor gene(s) other than
SMAD4 on 18q. DUSP6 at 12q21-q22 is frequently abrogated by
loss of expression in invasive ductal adenocarcinomas despite
fairly preserved expression in PanIN, which suggests that DUSP6
works as a tumor suppressor in pancreatic carcinogenesis.
Restoration of chromosome 12 also suppresses growths of
pancreatic cancer cells despite the recovery of expression of
DUSP6; the existence of yet another tumor suppressor gene on
12q is strongly suggested. Understanding the molecular
mechanisms of pancreatic carcinogenesis will likely provide
novel clues for preventing, detecting, and ultimately curing this
life-threatening disease. (Cancer Sci 2006; 97: 1–7)
ancreatic cancer is the ﬁfth leading cause of cancer death
in men, the sixth in women, in Japan and other developed
The ﬁve-year survival rate for pancreatic cancer
is very low, less than 10%,
but both the incidence and
mortality of pancreatic cancer are increasing.
indicates that current interventions to prevent, diagnose, and
cure the disease are far from satisfactory. We need to develop
novel and efﬁcient procedures to medicate patients with this
cancer; this need has driven many researchers to intensive
investigations of the molecular mechanisms of the development
and progression of pancreatic cancer to detect the molecular
clues that are valuable for the invention of novel procedures.
This review focuses on the elucidation of current knowledge
about the molecular insights of pancreatic carcinogenesis.
Genomic analysis of pancreatic cancer
Pancreatic ductal adenocarcinoma (PDA), the most common
type of pancreatic cancer, harbors complicated aberrations of
chromosomal alleles, that is, losses in multiple chromosome
arms, including 1p, 3p, 4q, 6q, 8p, 9p, 12q, 17p, 18q, and 21q,
and gains in 8q and 20q.
The aberrations are very characteristic
for comparing PDA with other types of cancer, most of which
reveal aberrations in fewer numbers of chromosomal regions.
The regions where losses occur are suggested to harbor tumor
suppressor genes (TSGs); those where gains occur, to harbor
oncogenes. Detailed analyses of loss of heterozygosity (LOH)
using microsatellite markers indicates several particularly
lost regions in 1p, 6q, 9p, 12q, 17p, and 18q; three smallest
regions of overlap (SROs) in 6q
and two in 12q
identiﬁed. However, no conclusive candidate TSG has been
identiﬁed. In 1p, several candidate genes such as TP73, RIZ,
ICAT, and RUNX3 were analyzed,
but alterations in these
genes were rather rare in pancreatic cancer. Future efforts will
disclose the conclusion of TSGs in these chromosome arms.
Signiﬁcant concordance of LOHs were found between 6q
and 17p and between 12q and 18q, and LOHs of 12q, 17p and
18q were reported to be associated with poor prognosis of
patients with PDA.
A study using probes to detect aberrations
of speciﬁc chromosomal regions including 8q24, 9p21,
17p13, 18q21 and 20q11 by ﬂuorescence in situ hybridiza-
tion in cells in pancreatic juice taken from patients undergo-
ing endoscopic retrograde cholangiopancreatography was
performed to test the diagnostic relevance of these allelic
Aberrations of copy numbers were detected in
70% of patients with pancreatic neoplasms, but no aberrations
were detected in any of the patients without them. These
results showed that these characteristic allelic aberrations can
be used as diagnostic markers for pancreatic cancer.
The great majority of PDA cases harbor a gain-of-function
mutation of KRAS.
RAS is a GTP-binding protein involved
To whom correspondence should be addressed.
Abbreviations: GTP, guanosine triphosphate; HPDE, human pancreatic duct
epithelium; LOH, loss of heterozygosity; MAPK, mitogen-activated protein
kinase; MMCT, microcell-mediated chromosome transfer; PanIN, pancreatic
intraepithelial neoplasia; PDA, pancreatic ductal adenocarcinoma; SRO, small-
est region of overlap; TSG, tumor suppressor gene.
2 doi: 10.1111/j.1349-7006.2006.00134.x
© 2006 Japanese Cancer Association
in growth factor-mediated signal transduction pathways.
The mutations of KRAS are observed at codons 12, 13 and
61, and the overall frequencies are more than 90% in PDAs.
The mutations result in the generation of a constitutively
active form of RAS. The constitutively active RAS
intrinsically binds to GTP and gives uncontrolled stimulatory
signals to downstream cascades involving mitogen-activated
protein kinases (MAPKs). Mutations of KRAS are frequently
observed in pancreatic ductal precursor lesions/pancreatic
intraepithelial neoplasia (PanIN). The consistent mutations of
KRAS in PanIN as well as in PDA indicate that the activation
of pathways involving RAS is essential for pancreatic
carcinogenesis. However, the mutations of KRAS do not
appear to be sufﬁcient for the development of PDA. Pancreas-
speciﬁc endogenous expression of active Kras, Kras
genetically engineered mice results in the development of
PanIN frequently, but the development of PDA very
Transfection of the activated KRAS in HPDE
cells, the immortalized near-diploid ductal cells derived from
normal human pancreas, show partially transformed
These results suggest that additional genetic
and/or epigenetic events, in addition to the activation of
KRAS, are necessary for the development of PDA.
SHH is frequently overexpressed in PDAs as well as in
Pancreas-speciﬁc overexpression of SHH in genet-
ically engineered mice resulted in the development of PanIN.
Gene expression proﬁling of early PanIN indicated the aberrant
expression of foregut markers, which was suggested to be a
result of activation of the Hedgehog pathway in the lesion.
Suppression of the Hedgehog pathway showed suppressive
phenotypes of the cultured pancreatic cancer cells.
is a family molecule regulating cell fates in embryogenesis in
Drosophila as well as in vertebrates. Activation of the Hedgehog
signaling pathway by sporadic mutations or in familial con-
ditions such as Gorlin’s syndrome is known to be associated
with tumorigenesis in skin, the cerebellum, and skeletal mus-
These pieces of information suggest that the activation
of the Hedgehog pathway plays a role at the initial step of the
development of PanIN, subsequently progressing to PDA.
Gain of copy number of 20q is frequently observed in
PDAs, which indicates a possible existence of oncogene(s) in
this chromosome arm.
Several candidate oncogenes have
been isolated, including AURKA locating on 20q13.2.
AURKA encodes AURKA/STK15/Aurora-A kinase, an essen-
tial molecule involved in regulating the functions of centro-
somes, spindles, and kinetochores, which are required for
proper mitosis of cells.
AURKA is overexpressed in vari-
ous cancer tissues, including PDA, which is associated with
a higher grade of tumor and a poorer survival of patients with
This overexpression can induce checkpoint dis-
ruption by interfering with p53 function and tetraploidiza-
tion, possibly leading to aneuploidy;
these may be some
of the critical causes for a worsened prognosis. Depletion of
AURKA by RNA interference in human pancreatic cancer
cells resulted in marked growth suppression in vitro, abolish-
ment of tumorigenesity in vivo, and synergistic enhancement
of cytotoxicity of taxanes, chemotherapeutic agents interfer-
ing with the functions of the mitotic spindle.
vations indicate that the overexpression of AURKA plays
important roles in the progression of PDA.
Aberrations of suppressive pathways
As discussed in the previous section, PDAs have lost multiple
allelic regions hemizygously or homozygously. These regions
of loss may harbor tumor suppressor genes. Homozygous
deletion of 9p21 is frequently observed in PDA. This
region harbors CDKN2A /INK4A/p16. This gene is inactivated
frequently in PDA by deletion or mutation.
PDAs harboring wild-type CDKN2A, expression of the gene
is transcriptionally silenced by hypermethylation of the
promoter, which indicates that CDKN2A is inactivated in
virtually all PDAs
(Fig. 1). Expression of CDKN2A is lost
in moderate/low-grade PanINs.
Loss of Cdkn2a/Ink4a in
-expressing mice results in the develop-
ment of a poorly differentiated sarcomatoid locally invasive
carcinoma that is an unusual form in human PDA.
CDKN2A is a cyclin-dependent kinase inhibitor. It binds
to CDK4 and prevents interaction between CDK4 and
CCND1, which induces cell cycle arrest at G1 phase in
cooperation with normal RB function.
These pieces of
information suggest that the loss of CDKN2A occurs early
and enhances the oncogenic potential of activating KRAS in
PDAs have frequently lost 17p13.
The region harbors
TP53/p53, the gene frequently mutated in PDAs.
mutations have been observed as missense or nonsense ones;
the former type is more common than the latter in human
malignant tumors, including PDA.
TP53 is a DNA binding
protein functioning as a transcription factor modulating mol-
ecules pertaining to variety of functions mainly involved in
cell cycle arrest and apoptosis.
The missense mutations of
TP53 are preferentially observed in its DNA binding domain,
which abrogates the binding capacity. The missense-mutated
TP53 proteins abnormally accumulated in the nucleus by
suppressed turnover, which is observed as if the protein were
overexpressed immunohistochemically (Fig. 1). Abnormal
accumulation of TP53 is frequently observed in high grade/
late PanIN lesions as well.
Targeted concomitant endog-
enous expression of Trp53
to the mouse
pancreas revealed the cooperative development of invasive
and metastatic ductal carcinoma characterized by loss of wild
type allele of Trp53 and diverse chromosomal instability,
which recapitulates human PDA.
Missense mutated Trp53
can inhibit Trp63 and Trp73 activity and increase its transfor-
These observations suggest that the aber-
ration of TP53 function under activated KRAS in pancreatic
ductal cells induces chromosomal instability and additional
genetic aberrations that can advance carcinogenic pathways
to invasive ductal carcinoma.
Familial pancreatic cancer
Some tumors develop in a hereditary manner; examples
include retinoblastoma, familial adenomatous polyposis,
breast cancer, neuroﬁbromatosis, and multiple endocrine
neoplasia. Such familial syndromes gave valuable clues for
the isolation of responsible genes.
The isolation of BRCA2
on chromosome 13 was accelerated by the identiﬁcation of a
homozygous deletion in pancreatic cancer,
but the great
majority of pancreatic cancers do not harbor mutation in this
Furukawa et al. Cancer Sci | January 2006 | vol. 97 | no. 1 | 3
© 2006 Japanese Cancer Association
gene. Several familial pancreatic cancer pedigrees have been
reported and positive linkage analysis was detected,
isolation of the responsible gene(s) is yet to be accomplished.
Impact of loss of chromosome 18q
Chromosome 18q is frequently deleted hemizygously and/or
homozygously in a vast majority of PDAs.
identiﬁed in the homozygously deleted region at 18q21.1.
SMAD4 is abrogated in approximately 50% of PDAs either
by homozygous deletion or mutation.
SMAD4 is frequently lost in high-grade/late PanIN lesions as
well as in PDA
(Fig. 1). SMAD4 is a signal mediator
involved in the transforming growth factor-β signaling
pathway that plays important roles in the negative regulation
of cell proliferation, as well as induction of extracellular
Fig. 1. Aberrations of multiple molecules in pancreatic ductal
adenocarcinoma (P). Note loss of expressions of CDKN2A (panel b),
SMAD4 (panel d), and DUSP6 (panel e) and abnormal accumulation
of TP53 (panel c). Panel a, hematoxylin and eosin staining. N,
4 doi: 10.1111/j.1349-7006.2006.00134.x
© 2006 Japanese Cancer Association
matrices, angiogenesis, and immune suppression.
comprises a hetero-multimer with SMAD2 and SMAD3,
which translocates into the nucleus and functions as a
transcription factor cooperating with p300/CBP.
Restoration of SMAD4 in SMAD4-deleted pancreatic cancer
cells resulted in no alteration of cell growth in vitro but the
abolition of tumorigenesity in immunodeﬁcient mice due to
suppression of angiogenesis, which suggests that SMAD4
functions as a suppressor of tumorigenesis by interfering
with interactions between epithelial cells and stromal cells.
Although loss of heterozygosity at chromosome 18q is an
overwhelming event in PDAs, occurring in 80– 90% of them,
the complete SMAD4 inactivation, namely a two-hit
mutation, is found in approximately 50%.
papillary-mucinous neoplasms of the pancreas, one of the
precursor types of neoplasms of PDA, loss of 18q is fre-
quently observed despite exclusive preservations of expres-
sions of SMAD4.
Homozygous deletion telomeric of the
SMAD4 locus is observed in some fractions of PDAs.
These observations indicate a possible existence of unknown
TSG(s) on 18q. To test this possibility, introduction of an
additional copy of chromosome 18 into cultured pancreatic
cancer cells with or without SMAD4 inactivation was per-
formed by microcell-mediated chromosome transfer
The transferred cells revealed a marked growth
retardation, loss of ability for anchorage-independent growth,
and modest invasiveness in vitro. The in vivo tumorigenic
ability of the transferred cells was signiﬁcantly reduced.
These results were obtained unanimously throughout the
transferred cells despite their different SMAD4 functional
Moreover, the chromosome 18-transferred cells
revealed marked reductions of metastatic ability in experi-
mental in vivo models.
These observations strongly sug-
gest that a TSG(s), particularly a metastasis-suppressing
gene(s), other than SMAD4, exists on 18q, and it is involved
in pancreatic carcinogenesis.
Tumor suppressor on chromosome 12q
Loss of heterozygosity at chromosome 12q is a frequent
aberration in PDAs.
Fine mapping of LOH by micro-
satellite analysis employing markers encompassing the entire
long arm of chromosome 12 at every few centi-morgans
uncovered two SROs; one at 12q21 and the other at 12q22-
The mapping of expressed sequence tags in and
around these regions to clone candidate tumor suppressor
genes resulted in the isolation of DUSP6/MKP-3 at 12q21-
No possible function-affecting mutations were
observed, but the DUSP6 mRNA expressions was strongly
As shown in Fig. 1, expression of DUSP6 was
markedly reduced and/or abolished in PDAs, especially in
the poorly differentiated type, despite its fairly good
preservation in PanINs.
The abrogation of expression of
DUSP6 is associated with hypermethylation of a possible
control region of the DUSP6 gene.
DUSP6 is a dual
speciﬁcity phosphatase that speciﬁcally binds and depho-
sphorylates MAPK1, which makes a feedback loop to
regulate a physiological activity of MAPK1/ERK2.
cultured pancreatic cancer cells lacking expression of DUSP6
tend to show constitutively active MAPK1, which suggests
that loss of function of DUSP6 could induce constitutive
activation of MAPK1.
Exogenous overexpression of DUSP6
in DUSP6-abrogated pancreatic cancer cells results in growth
suppression and the induction of apoptosis.
observations indicate that epigenetic silencing of DUSP6 is
one of the crucial causes of the pathogenesis of PDAs.
How can the abrogation of DUSP6 be interpreted in pan-
creatic carcinogenesis and progression? As already noted,
80–90% of PDAs harbor the gain-of-function mutation of
KRAS encodes RAS, which acts as a molecular
switch of downstream signal cascades including RAF1-
MAP2K-MAPK1. The mutated KRAS generates a constitu-
tively active RAS that hyperstimulates the downstream
cascades. In the negative feedback loop manner, the hyperac-
tivated MAPK1 would activate DUSP6, which in turn can
suppress the extraordinarily activated MAPK1. However, the
abrogation of DUSP6 may result in loss of the feedback loop,
which can lead to constitutive activation of MAPK1. The
constitutive active MAPK1 may translocate into the nucleus
and activate transcription factors that drive numerous effector
genes, which could contribute to uncontrolled cell growth
and cellular oncogenesis (Fig. 2). From these points of view,
DUSP6 functions as a tumor suppressor in the pancreatic car-
cinogenic pathway that is exclusively surmounted under the
activated RAS phenotype.
The tumor suppressive activity
of DUSP6 is also interpreted by recent reports that include
the downregulation of DUSP6 in leukemic cells, involvement
in induction of apoptosis by chemotherapy in leukemic cells,
suppressive roles in experimental skin carcinogenesis, and
involvement in the growth suppression of Jurkat T cells.
The abrogation of expression of DUSP6 is conﬁned in invasive
carcinoma, whereas aberrations of other major suppressive
molecules are observed in PanINs.
This ﬁnal ﬁnding
suggests that DUSP6 functions as a gatekeeper from PanIN
to invasive carcinoma, which is independent of other major
tumor suppressors (Fig. 3).
Because the precise localization of DUSP6, the candidate
TSG in 12q, is outside of SRO in this region,
mediated introduction of chromosome 12 was performed, and
it was found that the hybrid cells showed growth suppression
Fig. 2. The RAS-MAPK pathway with abrogation of DUSP6. Active
RAS generated by mutated KRAS activates downstream cascades
including RAF1-MAP2K1-MAPK1. Loss of expression of DUSP6 results
in abrogation of the feedback loop between MAPK1 and DUSP6
and leads to constitutive activation of MAPK1, which eventually
results in invasive phenotypes.
Furukawa et al. Cancer Sci | January 2006 | vol. 97 | no. 1 | 5
© 2006 Japanese Cancer Association
in vivo through angiogenesis inhibition.
sis revealed that expression of DUSP6 remained at the sup-
pressed level even in hybrid cells.
Therefore, a TSG(s)
beside DUSP6 is hidden in 12q that should be unveiled in
PDAs harbor complicated combinations of aberrations of
alleles. These aberrations are distinctive in pancreatic ductal
adenocarcinoma and are useful as diagnostic markers. The
promotion of pancreatic carcinogenesis is obviously initiated
by mutation of KRAS and aberrant expression of SHH. Over-
expression of AURKA mapping on 20q13.2 may signiﬁcantly
enhance overt tumorigenesity. Aberrations of tumor suppressor
genes synergistically accelerate the progression of carcinogenesis
through PanIN to PDA. Abrogation of CDKN2A occurs in
low-grade/early PanIN, whereas aberrations of TP53 occur in
high-grade/late PanIN; they may play different roles in the
progression of carcinogenesis. SMAD4 may play a
suppressive role in tumorigenesis by inhibiting angiogenesis.
Restoration of chromosome 18 in pancreatic cancer cells
results in tumor suppressive phenotypes regardless of
SMAD4 status, which suggests the possible existence of a
yet-to-be discovered TSG(s) in addition to SMAD4. DUSP6
at 12q21-q22 is frequently abrogated by loss of expression in
invasive ductal adenocarcinomas despite fairly preserved
expression in PanINs, which suggests that DUSP6 is a tumor
suppressor functioning as a gatekeeper of pancreatic
carcinogenesis. Restoration of chromosome 12 in pancreatic
cancer cells has revealed tumor suppressive phenotypes in
vivo without recovery of DUSP6 expression; a buried TSG(s)
in 12q is awaiting our discovery. At present, the major
pancreatic carcinogenic pathway can be modeled by
involving these key molecules (Fig. 3). There is a possibility
of innovation for accurate and effective diagnosis using the
cells obtained from the pancreatic juice and the molecules in
this schema. For this purpose, we must improve this schema
by adding more molecules. The understanding of the
molecular mechanisms of pancreatic carcinogenesis will
likely provide novel clues for preventing, detecting and
ultimately curing patients with this life-threatening disease.
We are grateful to all the members of the pancreatic cancer
research group in our laboratory, the surgeons and physicians
led by Drs Seiki Matsuno and Tooru Shimosegawa, respec-
tively, at Tohoku University Hospital, and all the collabora-
tors for continuing fruitful collaborations for many years. We
are also grateful to Dr Barbara Lee Smith Pierce (Professor,
University of Maryland University College) for editorial
work in the preparation of this manuscript. This work was
supported by the Ministries of Education, Culture, Sports,
Science and Technology of Japan, Health, Labor and Welfare
of Japan, and many non-proﬁt foundations.
1 Matsuno S, Egawa S, Fukuyama S et al. Pancreatic Cancer Registry in
Japan: 20 years of experience. Pancreas 2004; 28: 219–30.
2 Nomura K, Sobue T, Honma I et al. eds. Cancer statistics in Japan
2003. Tokyo: Foundation for Promotion of Cancer Research (FPCR);
3 Fukushige S, Waldman FM, Kimura M et al. Frequent gain of copy
number on the long arm of chromosome 20 in human pancreatic
adenocarcinoma. Genes Chromosomes Cancer 1997; 19: 161–9.
4 Abe T, Makino N, Furukawa T et al. Identiﬁcation of three commonly
deleted regions on chromosome arm 6q in human pancreatic cancer.
Genes Chromosomes Cancer 1999; 25: 60–4.
5 Kimura M, Abe T, Sunamura M, Matsuno S, Horii A. Detailed deletion
mapping on chromosome arm 12q in human pancreatic adenocarcinoma:
identiﬁcation of a 1-cM region of common allelic loss. Genes
Chromosomes Cancer 1996; 17: 88–93.
6 Kimura M, Furukawa T, Abe T et al. Identiﬁcation of two common
regions of allelic loss in chromosome arm 12q in human pancreatic
cancer. Cancer Res 1998; 58: 2456 – 60.
Fig. 3. Molecular pathways of pancreatic carcinogenesis. Activation of KRAS and SHH along with inactivation of CDKN2A contribute to the
formation of low-grade pancreatic intraepithelial neoplasia (PanIN). Additional inactivation of TP53 and SMAD4 contributes to one step up
the carcinogenesis stairs; the tumors turn into high-grade PanIN. Finally, inactivation of DUSP6 leads to pancreatic ductal adenocarcinoma.
PDA, pancreatic ductal adenocarcinoma.
6 doi: 10.1111/j.1349-7006.2006.00134.x
© 2006 Japanese Cancer Association
7 Han S, Semba S, Abe T et al. Infrequent somatic mutations of the p73
gene in various human cancers. Eur J Surg Oncol 1999; 25: 194–8.
8 Sakurada K, Furukawa T, Kato Y, Kayama T, Huang S, Horii A. RIZ,
the retinoblastoma protein interacting zinc ﬁnger gene, is mutated in
genetically unstable cancers of the pancreas, stomach, and colorectum.
Genes Chromosomes Cancer 2001; 30: 207–11.
9 Imai M, Nakamura T, Akiyama T, Horii A. Infrequent somatic mutations
of the ICAT gene in various human cancers with frequent 1p-LOH and/
or abnormal nuclear accumulation of β-catenin. Oncol Rep 2004; 12:
10 Li J, Kleeff J, Guweidhi A et al. RUNX3 expression in primary and
metastatic pancreatic cancer. J Clin Pathol 2004; 57: 294–9.
11 Yatsuoka T, Sunamura M, Furukawa T et al. Association of poor
prognosis with loss of 12q, 17p, and 18q, and concordant loss of 6q/17p
and 12q/18q in human pancreatic ductal adenocarcinoma. Am J
Gastroenterol 2000; 95: 2080–5.
12 Fukushige S, Furukawa T, Satoh K et al. Loss of chromosome 18q is an
early event in pancreatic ductal tumors. Cancer Res 1998; 58: 4222–6.
13 Almoguera C, Shibata D, Forrester K, Martin J, Arnheim N, Perucho M.
Most human carcinomas of the exocrine pancreas contain mutant c-K-ras
genes. Cell 1988; 53: 549 –54.
14 Gutkind JS. Signaling Networks and Cell Cycle Control: The Molecular
Basis of Cancer and Other Diseases. Totowa NJ: Humana Press, 2000.
15 Hingorani SR, Petricoin EF, Maitra A et al. Preinvasive and invasive
ductal pancreatic cancer and its early detection in the mouse. Cancer
Cell 2003; 4: 437–50.
16 Qian J, Niu J, Li M, Chiao PJ, Tsao MS. In vitro modeling of human
pancreatic duct epithelial cell transformation deﬁnes gene expression
changes induced by K-ras oncogenic activation in pancreatic
carcinogenesis. Cancer Res 2005; 65: 5045–53.
17 Thayer SP, di Magliano MP, Heiser PW et al. Hedgehog is an early and
late mediator of pancreatic cancer tumorigenesis. Nature 2003; 425:
18 Berman DM, Karhadkar SS, Maitra A et al. Widespread requirement for
Hedgehog ligand stimulation in growth of digestive tract tumours. Nature
2003; 425: 846–51.
19 Prasad NB, Biankin AV, Fukushima N et al. Gene expression proﬁles in
pancreatic intraepithelial neoplasia reﬂect the effects of Hedgehog
signaling on pancreatic ductal epithelial cells. Cancer Res 2005; 65:
20 Sen S, Zhou H, White RA. A putative serine/threonine kinase encoding
gene BTAK on chromosome 20q13 is ampliﬁed and overexpressed in
human breast cancer cell lines. Oncogene 1997; 14: 2195–200.
21 Marumoto T, Zhang D, Saya H. Aurora-A – a guardian of poles. Nat Rev
Cancer 2005; 5: 42–50.
22 Li D, Zhu J, Firozi PF et al. Overexpression of oncogenic STK15/BTAK/
Aurora A kinase in human pancreatic cancer. Clin Cancer Res 2003; 9:
23 Rojanala S, Han H, Munoz RM et al. The mitotic serine threonine
kinase, Aurora-2, is a potential target for drug development in human
pancreatic cancer. Mol Cancer Ther 2004; 3: 451–7.
24 Liu Q, Kaneko S, Yang L et al. Aurora-A abrogation of p53 DNA
binding and transactivation activity by phosphorylation of serine 215. J
Biol Chem 2004; 279: 52175 – 82.
25 Zhang D, Hirota T, Marumoto T et al. Cre-loxP-controlled periodic
Aurora-A overexpression induces mitotic abnormalities and hyper-
plasia in mammary glands of mouse models. Oncogene 2004; 23:
26 Hata T, Furukawa T, Sunamura M et al. RNA interference targeting
aurora kinase A suppresses tumor growth and enhances the taxane
chemosensitivity in human pancreatic cancer cells. Cancer Res 2005; 65:
27 Caldas C, Hahn SA, da Costa LT et al. Frequent somatic mutations and
homozygous deletions of the p16 (MTS1) gene in pancreatic
adenocarcinoma. Nat Genet 1994; 8: 27–32.
28 Schutte M, Hruban RH, Geradts J et al. Abrogation of the Rb/p16 tumor-
suppressive pathway in virtually all pancreatic carcinomas. Cancer Res
1997; 57: 3126–30.
29 Moskaluk CA, Hruban RH, Kern SE. p16 and K-ras gene mutations in
the intraductal precursors of human pancreatic adenocarcinoma. Cancer
Res 1997; 57: 2140–3.
30 Furukawa T, Fujisaki R, Yoshida Y et al. Distinct progression pathways
involving the dysfunction of DUSP6/MKP-3 in pancreatic intraepithelial
neoplasia and intraductal papillary-mucinous neoplasms of the pancreas.
Mod Pathol 2005; 18: 1034– 42.
31 Aguirre AJ, Bardeesy N, Sinha M et al. Activated Kras and Ink4a/Arf
deﬁciency cooperate to produce metastatic pancreatic ductal
adenocarcinoma. Genes Dev 2003; 17: 3112–26.
32 Serrano M, Hannon GJ, Beach D. A new regulatory motif in cell-cycle
control causing speciﬁc inhibition of cyclin D/CDK4. Nature 1993; 366:
33 Casey G, Yamanaka Y, Friess H et al. p53 mutations are common in
pancreatic cancer and are absent in chronic pancreatitis. Cancer Lett
1993; 69: 151–60.
34 Redston MS, Caldas C, Seymour AB et al. p53 mutations in pancreatic
carcinoma and evidence of common involvement of homocopolymer
tracts in DNA microdeletions. Cancer Res 1994; 54: 3025–33.
35 Nakamura Y. Isolation of p53-target genes and their functional analysis.
Cancer Sci 2004; 95: 7–11.
36 Hingorani SR, Wang L, Multani AS et al. Trp53
cooperate to promote chromosomal instability and widely metastatic
pancreatic ductal adenocarcinoma in mice. Cancer Cell 2005; 7: 469–
37 Lang GA, Iwakuma T, Suh YA et al. Gain of function of a p53 hot spot
mutation in a mouse model of Li-Fraumeni syndrome. Cell 2004; 119:
38 Vogelstein B, Kinzler KW. The Genetic Basis of Human Cancer, 2nd
edn. New York: McGraw-Hill, 2002.
39 Schutte M, da Costa LT, Hahn SA et al. Identiﬁcation by representational
difference analysis of a homozygous deletion in pancreatic carcinoma
that lies within the BRCA2 region. Proc Natl Acad Sci USA 1995; 92:
40 Eberle MA, Pfutzer R, Pogue-Geile KL et al. A new susceptibility locus
for autosomal dominant pancreatic cancer maps to chromosome 4q32–
34. Am J Hum Genet 2002; 70: 1044 – 8.
41 Klein AP, Beauty TH, Bailey-Wilson JE, Brune KA, Hruban RH,
Petersen GM. Evidence for a major gene inﬂuencing risk of pancreatic
cancer. Genet Epidemiol 2002; 23: 173 – 49.
42 Hahn SA, Schutte M, Hoque AT et al. DPC4, a candidate tumor
suppressor gene at human chromosome 18q21.1. Science 1996; 271:
43 Rozenblum E, Schutte M, Goggins M et al. Tumor-suppressive pathways
in pancreatic carcinoma. Cancer Res 1997; 57: 1731– 4.
44 Wilentz RE, Iacobuzio-Donahue CA, Argani P et al. Loss of expression
of Dpc4 in pancreatic intraepithelial neoplasia: evidence that DPC4
inactivation occurs late in neoplastic progression. Cancer Res 2000; 60:
45 Miyazono K, Suzuki H, Imamura T. Regulation of TGF-beta signal-
ing and its roles in progression of tumors. Cancer Sci 2003; 94: 230–
46 Duda DG, Sunamura M, Lefter LP et al. Restoration of SMAD4 by gene
therapy reverses the invasive phenotype in pancreatic adenocarcinoma
cells. Oncogene 2003; 22: 6857–64.
47 Inoue H, Furukawa T, Sunamura M, Takeda K, Matsuno S, Horii A.
Exclusion of SMAD4 mutation as an early genetic change in human
pancreatic ductal tumorigenesis. Genes Chromosomes Cancer 2001; 31:
48 Hilgers W, Song JJ, Haye M, Hruban RR, Kern SE, Fearon ER.
Homozygous deletions inactivate DCC, but not MADH4/DPC4/SMAD4,
in a subset of pancreatic and biliary cancers. Genes Chromosomes
Cancer 2000; 27: 353–7.
49 Lefter LP, Furukawa T, Sunamura M et al. Suppression of the
tumorigenic phenotype by chromosome 18 transfer into pancreatic
cancer cell lines. Genes Chromosomes Cancer 2002; 34: 234– 42.
50 Lefter LP, Sunamura M, Furukawa T et al. Inserting chromosome 18 into
pancreatic cancer cells switches them to a dormant metastatic phenotype.
Clin Cancer Res 2003; 9: 5044–52.
51 Furukawa T, Yatsuoka T, Youssef EM et al. Genomic analysis of
DUSP6, a dual speciﬁcity MAP kinase phosphatase, in pancreatic
cancer. Cytogenet Cell Genet 1998; 82: 156–9.
52 Furukawa T, Sunamura M, Motoi F, Matsuno S, Horii A. Potential tumor
suppressive pathway involving DUSP6/MKP-3 in pancreatic cancer. Am
J Pathol 2003; 162: 1807–15.
53 Xu S, Furukawa T, Kanai N, Sunamura M, Horii A. Abrogation of
DUSP6 by hypermethylation in human pancreatic cancer. J Hum Genet
2005; 50: 159–67.
54 Keyse SM. Protein phosphatases and the regulation of mitogen-activated
protein kinase signalling. Curr Opin Cell Biol 2000; 12: 186 –92.
55 Furukawa T, Horii A. Molecular pathology of pancreatic cancer: in quest
of tumor suppressor genes. Pancreas 2004; 28: 253–6.
56 Segal E, Friedman N, Koller D, Regev A. A module map showing
conditional activity of expression modules in cancer. Nat Genet 2004;
57 Powles T, te Poele R, Shamash J et al. Cannabis-induced cytotoxicity in
leukemic cell lines: the role of the cannabinoid receptors and the MAPK
pathway. Blood 2005; 105: 1214–21.
Furukawa et al. Cancer Sci | January 2006 | vol. 97 | no. 1 | 7
© 2006 Japanese Cancer Association
58 Warmka JK, Mauro LJ, Wattenberg EV. Mitogen-activated protein
kinase phosphatase-3 is a tumor promoter target in initiated cells that
express oncogenic Ras. J Biol Chem 2004; 279: 33085–92.
59 Ito T, Tsukumo S, Suzuki N et al. A constitutively active
arylhydrocarbon receptor induces growth inhibition of Jurkat T cells
through changes in the expression of genes related to apoptosis and cell
cycle arrest. J Biol Chem 2004; 279: 25204–10.
60 Yamanaka S, Sunamura M, Furukawa T et al. Chromosome 12,
frequently deleted in human pancreatic cancer, may encode a tumor sup-
pressor gene that suppresses angiogenesis. Lab Invest 2004; 84: 1739–51.