title: Expression of multidrug resistance-associated protein 2 is involved in chemotherapy resistance in human pancreatic cancer.
abstract: Despite the recent introduction of the new anticancer agents gemcitabine (GEM) and TS-1, as well as combination regimens such as GEM plus cisplatin (CDDP), pancreatic cancer treatment remains relatively ineffective. Both intrinsic and acquired resistance to chemotherapy are major roadblocks to the successful treatment of pancreatic cancer patients. The aims of this study were to examine the expression of multidrug resistance-associated proteins (MRPs) MRP1, MRP2 and MRP3 and to evaluate the correlation between MRP2 expression and CDDP resistance in human pancreatic cancer. Five human pancreatic cancer cell lines and several surgically resected pancreatic cancer tissues were subjected to reverse-transcriptase (RT)-PCR, real-time PCR and immunohistochemical analysis. While MRP1 and MRP2 mRNA was expressed in all cell lines, MRP3 mRNA was only detected in two cell lines. In resected pancreatic cancer tissues, only MRP2 mRNA was expressed and it was overexpressed compared with normal pancreatic tissues. MRP2 protein expression was observed in 77.5% (31/40) of cancer tissues, primarily in the cytoplasm of cancer cells, but was not observed in normal pancreatic tissue. Two CDDP-resistant pancreatic cancer cell line SUIT-2 variants, SUIT-2-CD3 and SUIT-2-CD4, were established by continuously administering 10 nM CDDP to SUIT-2 cell lines for 3 and 4 months, respectively. Incubation of these cells with CDDP in the presence of anti-MRP2 antibody or the MRP2 inhibitor MK-571 in a growth inhibition assay demonstrated that the CDDP-resistant variants were more resistant to CDDP than the parent cell line and this resistance was diminished by either anti-MRP2 antibody or MK-571. Moreover, RT-PCR and real-time PCR revealed that while induction of MRP2 mRNA expression was increased in CDDP-resistant compared with parent cells, MRP1 and MRP3 expression remained unchanged. These observations suggest that MRP2 may correlate to intrinsic and acquired resistance for CDDP in human pancreatic cancer.
authors.affiliation: Department of Medicine and Molecular Science, Hiroshima University Graduate School of Biomedical Sciences, Minami-ku, Hiroshima 734-8551, Japan. bunjiro@hiroshima-u.ac.jp
authors.forename: Bunjiro
authors.initials: B
authors.lastname: Noma
authors.forename: Tamito
authors.initials: T
authors.lastname: Sasaki
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Serikawa
authors.forename: Kenso
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Motoki
authors.initials: M
authors.lastname: Inoue
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Itsuki
authors.forename: Michihiro
authors.initials: M
authors.lastname: Kamigaki
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Minami
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Chayama
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002945:Cisplatin / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011422:Propionates / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; D002945:Cisplatin; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011422:Propionates; D011804:Quinolines; D012333:RNA, Messenger; C000715087:ABCC2 protein, human; C114462:multidrug resistance-associated protein 3; C059141:verlukast; C421109:multidrug resistance-associated protein 1