Subsequently, there is a significant decrease in both MDR1 and Bcl-x(L) gene expression and an enhancement in caspase-3 activity and chemosensitivity in the breast tumor cells.
Single nucleotide polymorphisms in the multidrug resistance gene 1 (ABCB1): effects on its expression and clinicopathological characteristics in breast cancer patients.
Hypermethylation of the ABCB1 downstream gene promoter accompanies ABCB1 gene amplification and increased expression in docetaxel-resistant MCF-7 breast tumor cells.
The quantitative real-time polymerase chain reaction (Q-RT-PCR) technique was used to assess the MDR1 and MMP2 RNA expression levels in primary breast tumor and lymph nodal specimens.
Immunohistochemistry confirmed that breast carcinoma cells lackedP-glycoprotein expression; however, interstitial mononuclear cells, morphologically consistent with lymphocytes or macrophages did show immunostaining in some of these breast tumors.
MDR1/gp170 expression has been studied in breast cancer, but the prevalence of this expression and its role in breast tumor drug resistance are unclear.
Production of P-glycoprotein from the MDR1 upstream promoter is insufficient to affect the response to first-line chemotherapy in advanced breast cancer.
P-Glycoprotein RNA expression was positive in eight of 23 lymphomas and two of 12 colon tumors; however, many other normal and malignant tissues, including lung, bladder, and breast tumors, had low or undetectable levels of P-glycoprotein RNA expression.
However, transcripts derived from the MDR1 USP were detected in some drug-resistant cell lines and a high proportion of primary breast tumors (71.6%; n = 61), whereas they were present at low frequency in normal breast tissue (10%; n = 10).
The expression of MDR in breast tumors is related to their origination from a tissue that constitutively expresses Pgp as well as to the development of resistance during successive courses of chemotherapy.
The regulatory effect of Gal-1 on multidrug resistance (MDR) breast cancer cells is still unclear. qRT-PCR and western blot showed that Gal-1 and MDR gene 1 (MDR1) were both highly expressed in breast tumor tissues and cell lines.
We determined mRNA levels of BCRP, LRP, MRP1, MRP2, and MDR1 in 59 primary breast tumor specimens of patients who received chemotherapy as first-line systemic treatment after diagnosis of advanced disease.
Determination of P-glycoprotein, MDR-related protein 1, breast cancer resistance protein, and lung-resistance protein expression in leukemic stem cells of acute myeloid leukemia.
Among the 20 remaining genes, seven genes (CYP2A6, CYP2B6, FMO5, NAT1, SULT2B1, GSTM3 and ABCC11) showed significantly higher mRNA levels in ERalpha-positive breast tumors than in normal breast tissue, or showed higher mRNA levels in ERalpha-positive breast tumors than in ERalpha-negative breast tumors.
ABCC11 expression is regulated by estrogen in MCF7 cells, correlated with estrogen receptor alpha expression in postmenopausal breast tumors and overexpressed in tamoxifen-resistant breast cancer cells.