title: Doxorubicin transport by RALBP1 and ABCG2 in lung and breast cancer.
abstract: RALBP1 (RLIP76) is the major transporter of doxorubicin (DOX) in lung cancer cells, and that the difference in sensitivity of small cell lung cancer (SCLC) cells to DOX is due to differential phosphorylation by PKCalpha. Our recent studies have suggested that RALBP1 present in MCF-7 breast cancer cells has significantly lower specific activity for transport of DOX than wild-type recombinant protein, and its level of expression is significantly lower than that in lung cancer cells. In the present study, we have explored whether or not this is a generalized phenomenon for breast cancer, and have compared the relative contributions of RALBP1 and the ABC-family transporter, ABCG2 to total DOX transport activities in two SCLC (H1417 and H1618), two non-small cell lung cancer (NSCLC) (H358 and H520), and three breast cancer (T-47D, MDA-MB231, and MCF-7) cell lines. Results of these studies show lower protein expression and specific activity of RALBP1 in all three breast cancer cell lines as compared with lung cancer cell lines. Furthermore, we demonstrate that RALBP1 contributes only a minor fraction of DOX transport activity in breast cancer cell lines, suggesting that greater DOX sensitivity of breast cancer may be related to lower RALBP1 transporter activity and that the transport mechanisms involved in multidrug resistance of lung and breast cancer are distinct.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Arlington, TX 76019, USA.
authors.forename: Sharad S
authors.initials: SS
authors.lastname: Singhal
authors.forename: Jyotsana
authors.initials: J
authors.lastname: Singhal
authors.forename: Maya P
authors.initials: MP
authors.lastname: Nair
authors.forename: A G
authors.initials: AG
authors.lastname: Lacko
authors.forename: Yogesh C
authors.initials: YC
authors.lastname: Awasthi
authors.forename: Sanjay
authors.initials: S
authors.lastname: Awasthi
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D001692:Biological Transport; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000493:pharmacokinetics*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D008954:Models, Biological; D009363:Neoplasm Proteins / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D020690:GTPase-Activating Proteins; D009363:Neoplasm Proteins; C095637:RALBP1 protein, human; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D004317:Doxorubicin