Identification of F-box/LLR-repeated protein 17 as potential useful biomarker for breast cancer therapy.
BACKGROUND
The expression and activity of ribonucleotide reductase (RR) has been associated with resistance to multiple drugs in human cancer. The use of antisense oligonucleotide drug, GTI-2040, a 20-mer phosphorothioate oligonucleotide complemented to the human RR M2 subunit mRNA, represents an effective strategy for inhibiting RR. The increased specificity due to the anti-resistance effect of GTI-2040 may also lead to a more favorable therapeutic outcome.


METHODS
To understand the molecular mechanism underlying RR inhibition, patients' blood samples were analyzed using multiple dimensional proteomics technology via matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry.


RESULTS
A major difference occurred at 5k m/z in the MALDI profile, which appeared only in the non-responsive group and diminished after GTI-2040 treatment. This specific peptide peak remained at the basal level in responsive patients. The peak was identified to represent the F-box/LLR-repeat protein 17 (FBXL17) through nanoelectrospray ionization liquid chromatography-tandem mass spectrometry (nanoESI LC-MS/MS). Further characterization revealed that FBXL17 [corrected] directly interacts with the human RR M2 (RRM2) subunit to promote hRRM2 overexpression in the breast cancer cell line MCF-7.


CONCLUSIONS
Validation of this protein using real-time RT-PCR indicates the F-box protein 17 (FBXL17) can serve as a therapeutic target and surrogate marker for breast cancer therapy.
Xiao
Gary Guishan
GG
Department of Clinical & Molecular Pharmacology, City of Hope National Cancer Center, Duarte, CA 91010-3000, USA.
Zhou
Bing-Sen
BS
Somlo
George
G
Portnow
Jana
J
Juhasz
Agnes
A
Un
Frank
F
Chew
Helen
H
Gandara
David
D
Yen
Yun
Y
D000970:Antineoplastic Agents / Q000494:pharmacology*; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D044783:F-Box Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D009838:Oligodeoxyribonucleotides / Q000627:therapeutic use*; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D017931:DNA Primers; D044783:F-Box Proteins; C532335:FBXL17 protein, human; D009838:Oligodeoxyribonucleotides; C464617:GTI2040