RESUMO
The multifunctional mammalian protein YB-1 is involved in multiple DNA- and mRNA-dependent events in the cell and regulates gene expression at different levels. The intracellular localization and relative mRNA content of YB-1 in the breast tumors were studied. The presence of cells with nuclear YB-1 localization in the tumor cell population is a poor predictor that correlates with larger tumors (more than 5 cm). The high YB-1 mRNA content in the breast tumors promotes metastasis of small neoplasms and patients with breast cancer who have high tumor tissue YB-1 mRNA levels may referred to as an early distant metastasis risk group. The findings suggest that combined determination of YB-1 intercellular localization and mRNA levels can ensure a more reliable prognosis of breast cancer.
Assuntos
Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas Nucleares/metabolismo , RNA Mensageiro/metabolismo , Neoplasias da Mama/patologia , Núcleo Celular/metabolismo , Núcleo Celular/patologia , Citoplasma/metabolismo , Citoplasma/patologia , Feminino , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína 1 de Ligação a Y-BoxRESUMO
In a past decade became evident that phosphatidylinositol-3-kinase controlled signal transduction cascade (PI3K/Akt/PTEN/mTOR) is implicated in resistance of tumor cells to anticancer drugs. Another well studied mechanism of multidrug resistance is associated with the activity of drug transporters of ABC superfamily (first of all P-glycoprotein (Pgp), MRP1, BCRP). Several mechanisms of cell defense can be turned on in one cell. The interconnections between different mechanisms involved in drug resistance are poorly studied. In the present study we used PC3 and DU145 human prostate cell lines to show that PTEN functional status determines level of cell resistance to some drugs, it correlates with expression level of MRP1 and BCRP proteins. We showed that Pgp is not involved in development of drug resistance in these cells. Transfection of PTEN into PTEN-deficient PC3 as well as rapamycin treatment caused the inhibition of PI3K/Akt/mTOR signaling and resulted in cell sensitization to the action of doxorubicin and vinblastine. We showed that PTEN transfection leads to the change in expression of MRP1 and BCRP. Our results show that in prostate cancer cells at least two mechanisms of drug resistance are interconnected. PTEN and mTOR signaling were shown: to be involved into regulation of MRP1 and BCRP.
