Camptothecin resistance: role of the ATP-binding cassette (ABC), mitoxantrone-resistance half-transporter (MXR), and potential for glucuronidation in MXR-expressing cells

TY - JOUR

T1 - Camptothecin resistance

T2 - role of the ATP-binding cassette (ABC), mitoxantrone-resistance half-transporter (MXR), and potential for glucuronidation in MXR-expressing cells

AU - Brangi, M

AU - Litman, Thomas

AU - Ciotti, M

AU - Nishiyama, K

AU - Kohlhagen, G

AU - Takimoto, C

AU - Robey, R

AU - Pommier, Y

AU - Fojo, T

AU - Bates, S E

PY - 1999/12/1

Y1 - 1999/12/1

N2 - The mitoxantrone resistance (MXR) gene encodes a recently characterized ATP-binding cassette half-transporter that confers multidrug resistance. We studied resistance to the camptothecins in two sublines expressing high levels of MXR: S1-M1-80 cells derived from parental S1 colon cancer cells and MCF-7 AdVp3,000 isolated from parental MCF-7 breast cancer cells. Both cell lines were 400- to 1,000-fold more resistant to topotecan, 9-amino-20(S)-camptothecin, and the active metabolite of irinotecan, 7-ethyl-10-hydroxycamptothecin (SN-38), than their parental cell lines. The cell lines demonstrated much less resistance to camptothecin and to several camptothecin analogues. Reduced accumulation and energy-dependent efflux of topotecan was demonstrated by confocal microscopy. A significant reduction in cleavable complexes in the resistant cells could be observed after SN-38 treatment but not after camptothecin treatment. In addition to topotecan and SN-38, MXR-overexpressing cells are highly resistant to mitoxantrone and epirubicin. Because these compounds are susceptible to glucuronidation, we examined UDP-glucurono-syltransferase (UGT) activity in parental and resistant cells by TLC. Glucuronides were found at equal levels in both parental and resistant colon cancer cell lines for epirubicin and to a lesser extent for SN-38 and mitoxantrone. Low levels of glucuronidation could also be detected in the resistant breast cancer cells. These results were confirmed by analysis of the UGT1A family mRNAs. We thus conclude that colon and breast cancer cells have a capacity for glucuronidation that could contribute to intrinsic drug resistance in colon cancer cells and may be acquired in breast cancer cells. The lack of selection for higher levels of UGT capacity in the colon cells suggests that high levels of expression of MXR alone are sufficient to confer resistance to the camptothecins.

AB - The mitoxantrone resistance (MXR) gene encodes a recently characterized ATP-binding cassette half-transporter that confers multidrug resistance. We studied resistance to the camptothecins in two sublines expressing high levels of MXR: S1-M1-80 cells derived from parental S1 colon cancer cells and MCF-7 AdVp3,000 isolated from parental MCF-7 breast cancer cells. Both cell lines were 400- to 1,000-fold more resistant to topotecan, 9-amino-20(S)-camptothecin, and the active metabolite of irinotecan, 7-ethyl-10-hydroxycamptothecin (SN-38), than their parental cell lines. The cell lines demonstrated much less resistance to camptothecin and to several camptothecin analogues. Reduced accumulation and energy-dependent efflux of topotecan was demonstrated by confocal microscopy. A significant reduction in cleavable complexes in the resistant cells could be observed after SN-38 treatment but not after camptothecin treatment. In addition to topotecan and SN-38, MXR-overexpressing cells are highly resistant to mitoxantrone and epirubicin. Because these compounds are susceptible to glucuronidation, we examined UDP-glucurono-syltransferase (UGT) activity in parental and resistant cells by TLC. Glucuronides were found at equal levels in both parental and resistant colon cancer cell lines for epirubicin and to a lesser extent for SN-38 and mitoxantrone. Low levels of glucuronidation could also be detected in the resistant breast cancer cells. These results were confirmed by analysis of the UGT1A family mRNAs. We thus conclude that colon and breast cancer cells have a capacity for glucuronidation that could contribute to intrinsic drug resistance in colon cancer cells and may be acquired in breast cancer cells. The lack of selection for higher levels of UGT capacity in the colon cells suggests that high levels of expression of MXR alone are sufficient to confer resistance to the camptothecins.

KW - ATP-Binding Cassette Transporters

KW - Antineoplastic Agents

KW - Antineoplastic Agents, Phytogenic

KW - Breast Neoplasms

KW - Camptothecin

KW - Cell Survival

KW - DNA Damage

KW - Drug Resistance, Multiple

KW - Epirubicin

KW - Female

KW - Glucuronides

KW - Glucuronosyltransferase

KW - Humans

KW - Microscopy, Confocal

KW - Mitoxantrone

KW - Polymerase Chain Reaction

KW - Topotecan

KW - Tumor Cells, Cultured

M3 - Journal article

C2 - 10606239

SN - 0008-5472

VL - 59

SP - 5938

EP - 5946

JO - Cancer Research

JF - Cancer Research

IS - 23

ER -