Thee SMAD4 Protein and Prognosi s of Pancreatic Ductall Adenocarcinoma

T Purpose:Purpose: SMAD4 (also called Dpc4) is a tumor suppressorr in the TGF-P signaling' pathway that is genetically inactivatedd in —55% of all pancreatic adenocarcinomas. Wee investigated whether prognosis after surgical resection forr invasive pancreatic adenocarcinoma is influenced by SMAD44 status. ExperimentalExperimental Design: Using immunohistochemistry, we characterizedd the SMAD4 protein status of 249 pancreatic adenocarcinomass resected from patients who underwent pancreaticoduodenectomypancreaticoduodenectomy (Whipple resection) at The Johns Hopkinss Hospital, Baltimore, MD, between 1990 and 1997. Thee SMAD4 gene status of 56 of 249 (22%) pancreatic carcinomass was also determined. A multivariat e Cox proportionall hazards model assesse d the relative risk of mortalit yy associated with SMAD4 status, adjusting for known prognosticc variables. Results:Results: Patients with pancreatic adenocarcinomas with SMAD44 protein expression had significantly longer survival (unadjustedd median survival was 19.2 months as compared withh 14.7 months in patients with pancreatic cancers lacking SMAD44 protein expression; P = 0.03). This SMAD4 survival benefitt persisted after adjustment for prognostic factors inReceivedd 6/13/01: revised 8/27/01: accepte d 8/29/01. Thee cost s of publication of this article were defrayed in pan by the paymentt of' page charges . This article must therefor e be hereby marked advertisementadvertisement in accordanc e with IS U.S.C. Section 1734 solel y to indicatee this fact. 11 To whom request s for reprints shoul d be addressed , at Division of Gastrointestina ll Pathology. 632 Ross Building, The Johns Hopkins Medicall Institutions. Baltimore. MD 21205. Phone: (410)955-3511 : Fax:: (410)614-0671 ; Email: mgogginsfajhmi.edu . :: The abbreviations used are: TGF-P, transforming growth factor p; IPMN. intraductall papillary mucinous neoplasm: CI, confidence interval eludingg tumor size, margins, lymph node status, pathological stage,, blood loss, and use of adjuvant chemoradiotherapy. The relativee hazard of mortalit y for cancers lacking SMAD4 after adjustingg for other prognostic factors was 1.36 (95% confidencee interval, 1.01nl.83; P = 0.04). Conclusion:Conclusion: Patients undergoing Whipple resection for pancreaticc adenocarcinoma survive longer if their cancers expresss SMAD4. INTRODUCTIO N N Pancreati cc carcinoma is a deadl y disease with a 5-year survivall of 3-5% (1). Currently, long-term survival from pancreati cc cancer is best achieved through surgical resection, which iss associate d with 5-year survival rates of 15-20% (range, 7-24%;; Refs. 2, 3). Survival is best among resected patient s withh smal carcinomas (<3 cm), negative lymph nodes, and negativee resection margins; this subgroup of patient s has a 5-yearr survival rate approaching 40% (1. 4). Adjuvant chemoradiotherapyy seems to further improve survival, although the optimall regimens are still under investigation (2, 5-10). Despite recentt improvement s in survival, most patient s who undergo surgicall resection ultimately die of their disease . Current prognosticc indicators such as tumor size, margin status, and lymph nodee involvement do not accuratel y predict respons e to treatmentt (1, 4. 5. 11). Apart from DNA index (12, 13), molecular alterationss common to pancreati c carcinoma have not yet been shownn to independentl y predict prognosi s after surgical resectionn once establishe d prognosti c markers are taken into account (14-18).. In addition to improving prognostication , new molecularr prognosti c markers would help to more accuratel y estimat e response ss to investigative treatment s and may identify the biologicall factors within pancreati c carcinomas that most influence survival. . Pancreati cc carcinoma is a geneti c disease characterize d by somati cc mutations of multiple genes, including the K-ras oncogenee and the tumor suppresso r genes pló, p53, and SMAD4 (19).. SMAD4 is a tumor suppresso r gene that is inactivated in —— 55% of pancreati c adenocarcinomas , either by the intrageni c mutationn of one allele in combination with the loss of the other allelee or by homozygous deletion of both alleles (20). In the cytoplasm.. SMAD4 protein mediates signal s from a family of TGF-PP ligands and their transmembran e receptor s through phosphorylationn of SMAD proteins, which heterodimeriz e with SMAD4.. This SMAD4/SMAD complex transmit s upstream signalss by translocating to the nucleus, binding to specific DNA sequences ,, and activating gene transcription (see Fig. 1). Many off the functions of TGF-fl and its related ligands, such as growth suppressio nn and apoptosis , are abrogated by inactivation of SMAD4SMAD4 (21). Wee hypothesize d that pancreati c adenocarcinoma s with inactivationn of SMAD4 would behave more aggressivel y than thosee with intact SMAD4. To evaluat e the clinical significance