In vivo expansion of MDR1-transduced cells accompanied by a post-transplantation chemotherapy regimen with mitomycin C and methotrexate.
BACKGROUND
A recurrent breast cancer patient received high-dose chemotherapy, a transplant of multidrug resistance 1 (MDR1)-transduced cells and four different protocols of post-transplantation chemotherapy. We report the analysis of MDR1-transduced cells in this patient.


METHODS
MDR1 transgene levels in the peripheral blood mononuclear cells of the patient were evaluated by polymerase chain reaction (PCR). Retroviral integration sites of the MDR1-transduced cells were identified by linear amplification-mediated (LAM)-PCR.


RESULTS
Twelve days after transplantation, approximately 1% of the peripheral blood mononuclear cells were MDR1 transgene-positive. The transgene levels decreased quickly, and were at low levels until day 504. A remarkable increase in MDR1 transgene-positive cells was observed on day 532, during combination chemotherapy with mitomycin C and methotrexate. Using LAM-PCR, 31 MDR1-transduced clones were identified, and eight of these were long-life clones that survived for more than 500 days. Among the 31 clones, ten had a retroviral integration site near genes listed in the Retroviral Tagged Cancer Gene (RTCG) Database. Two long-life clones, N-30 and N-31, had retroviral integration sites within the MDS1-EVI1 locus. Another two long-life clones had integration sites close to PRDM16 or CUEDC1.


CONCLUSIONS
These results suggest that MDR1-transduced cells were enriched in vivo by an MDR1 substrate, mitomycin C. The possible activation of EVI1 or other RTCGs by retroviral insertion may have affected the survival and persistence of a proportion of the transduced cells.
Division of Chemotherapy, Faculty of Pharmacy, Keio University, Tokyo, Japan.
Junko
J
Mitsuhashi
Hiroyo
H
Hosoyama
Satomi
S
Tsukahara
Kazuhiro
K
Katayama
Kohji
K
Noguchi
Yoshinori
Y
Ito
Kiyohiko
K
Hatake
Keisuke
K
Aiba
Shunji
S
Takahashi
Yoshikazu
Y
Sugimoto
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism*; D001943:Breast Neoplasms / Q000188:drug therapy*; D049109:Cell Proliferation / Q000187:drug effects; D002999:Clone Cells; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D052138:Genes, Neoplasm / Q000235:genetics; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D000074008:MDS1 and EVI1 Complex Locus Protein; D008727:Methotrexate / Q000494:pharmacology / Q000627:therapeutic use*; D016685:Mitomycin / Q000494:pharmacology / Q000627:therapeutic use*; D016133:Polymerase Chain Reaction; D011519:Proto-Oncogenes / Q000235:genetics; D012190:Retroviridae / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014161:Transduction, Genetic; D019076:Transgenes / Q000235:genetics; D016662:Virus Integration / Q000187:drug effects
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004268:DNA-Binding Proteins; D000074008:MDS1 and EVI1 Complex Locus Protein; C063575:MECOM protein, human; D014157:Transcription Factors; D016685:Mitomycin; D008727:Methotrexate