title: Role of RLIP76 in lung cancer doxorubicin resistance: I. The ATPase activity of RLIP76 correlates with doxorubicin and 4-hydroxynonenal resistance in lung cancer cells.
abstract: RLIP76 functions as an ATP-dependent transporter of amphiphilic chemotherapeutic drugs such as doxorubicin (DOX, adriamycin), as well as of glutathione-conjugates of endogenous electrophilic toxins such as 4-hydroxynonenal (4HNE). RLIP76 couples transport and ATP-hydrolysis with a 1:1 stoichiometry, making the ATPase activity of RLIP76 an excellent surrogate for its transport activity. Present studies were performed to determine the relationship of the RLIP76 ATPase activity with DOX and 4HNE resistance in a panel of 13 native human lung cancer cell lines. RLIP76 was purified from each cell line and homogeneity demonstrated by SDS-PAGE and amino acid composition analysis. Anti-RLIP76 antibodies were shown by Ouchterlony double immunodiffusion tests to be non-cross-reactive with any other proteins including P-glycoprotein (Pgp) or multidrug resistance associated protein (MRP). These antibodies completely immunoprecipitated ATPase activity of purified RLIP76 fractions, further confirming homogeneity of purified RLIP76. RLIP76 ATPase purified from NSCLC cell lines was about 2-fold more active than that from SCLC in the absence of the stimulator dinitrophenyl S-glutathione (206+/-47, n=7 vs. 94+/-22, n=6, nmol/min/mg protein, respectively), or in its presence (340+/-60, n=7 vs. 186+/-32, n=6, nmol/min/mg; p<0.01). Partial tryptic digest revealed a 44 kDa internal fragment of RLIP76 beginning at Thr-294 in NSCLC cell lines. This fragment was absent from all SCLC, suggesting the possibility that the activity of RLIP76 in SCLC and NSCLC is differentially regulated through post-translational modifications. Taken together, these findings suggest that RLIP76 activity is a general determinant of 4HNE and DOX resistance, and that its activity contributes to the drug-resistant phenotype of NSCLC.
authors.affiliation: Department of Chemistry and Biochemistry, University of Texas at Arlington, 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: Rajendra
authors.initials: R
authors.lastname: Sharma
authors.forename: Shivendra V
authors.initials: SV
authors.lastname: Singh
authors.forename: Piotr
authors.initials: P
authors.lastname: Zimniak
authors.forename: Yogesh C
authors.initials: YC
authors.lastname: Awasthi
authors.forename: Sanjay
authors.initials: S
authors.lastname: Awasthi
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000447:Aldehydes / Q000493:pharmacokinetics*; D000595:Amino Acid Sequence; D000970:Antineoplastic Agents / Q000493:pharmacokinetics*; D001692:Biological Transport; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism / Q000473:pathology*; D018288:Carcinoma, Small Cell / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D003429:Cross Reactions; D004317:Doxorubicin / Q000493:pharmacokinetics*; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D020690:GTPase-Activating Proteins; D005978:Glutathione / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D020014:K562 Cells; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D014357:Trypsin / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D020298:U937 Cells
chemical_list: D018528:ATP-Binding Cassette Transporters; D000447:Aldehydes; D000970:Antineoplastic Agents; D002352:Carrier Proteins; D020690:GTPase-Activating Proteins; D007074:Immunoglobulin G; D009363:Neoplasm Proteins; C095637:RALBP1 protein, human; D004317:Doxorubicin; D014357:Trypsin; D000251:Adenosine Triphosphatases; D005978:Glutathione; C027576:4-hydroxy-2-nonenal