Intracellular localization and content of YB-1 protein in multidrug resistant tumor cells.
The multifunctional mammalian protein YB-1 is a member of the large DNA- and RNA-binding protein family with an evolutionarily ancient cold-shock domain. YB-1 is involved in multiple DNA- and mRNA-dependent events and regulates gene expression at various levels. It can be found both in the nucleus and the cytoplasm. Bound to DNA in the cell nucleus, YB-1 functions as a transcription factor interacting with inverted CCAAT-box (Y-box) in promoters and enhancers of multiple genes. In particular, YB-1 regulates activity of the multidrug resistance (MDR) genes MDR1 and LRP. In tumors, YB-1 has been suggested to be an early and global marker of MDR. In this study, we compared amounts of YB-1 mRNAs and intracellular localization of YB-1 protein in six pairs of drug sensitive and drug resistant sublines of diverse tumors. We have shown that neither great increase in the level of YB-1 mRNA nor substantial increase in the number of cells with nuclear localization of YB-1 are obligatory traits of drug resistant tumor cell populations. However, the cells with highest amounts of YB-1 mRNA also demonstrated increased quantities of MDR1, MRP1, BCRP, and LRP mRNAs encoding different MDR proteins. Transfection of two different populations of drug-sensitive cells with YB-1 cDNA led to increase in the amount of YB-1 mRNA. The quantities of MRP1 and LRP mRNAs increased in both populations. Introduction of YB-1 small hairpin RNA (shRNA) resulted in decreased amounts of YB-1 mRNA, as well as MRP1, LRP, and MDR1 mRNAs (in three different cell lines). Our data suggest that although YB-1 regulates several MDR genes, it could not be regarded as a global marker of already formed drug resistant tumor cell populations. It is most likely that at the first steps of MDR development YB-1 activity is necessary for propagation of resistant cell populations rather than for maintenance of drug resistance.
Vaiman
A V
AV
Institute of Carcinogenesis, Blokhin Russian Cancer Research Center, Russian Academy of Medical Sciences, 115478 Moscow, Russia. vaiman@yandex.ru
Stromskaya
T P
TP
Rybalkina
E Yu
EY
Sorokin
A V
AV
Guryanov
S G
SG
Zabotina
T N
TN
Mechetner
E B
EB
Ovchinnikov
L P
LP
Stavrovskaya
A A
AA
D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D045325:HCT116 Cells; D006801:Humans; D007424:Intracellular Fluid / Q000737:chemistry / Q000378:metabolism*; D020014:K562 Cells; D007624:KB Cells; D008969:Molecular Sequence Data; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis / Q000235:genetics; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins; D034622:RNA Interference; D012320:RNA Polymerase III / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics; D020394:Vault Ribonucleoprotein Particles / Q000096:biosynthesis / Q000235:genetics; D051840:Y-Box-Binding Protein 1; D000099187:Major Vault Protein
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D012320:RNA Polymerase III; D012333:RNA, Messenger; D012367:RNA, Viral; D020394:Vault Ribonucleoprotein Particles; D051840:Y-Box-Binding Protein 1; D000099187:Major Vault Protein; C070856:YBX1 protein, human; C421109:multidrug resistance-associated protein 1