Doxorubicin treatment modulates chemoresistance and affects the cell cycle in two canine mammary tumour cell lines

Abstract

Background Doxorubicin (DOX) is widely used in both human and veterinary oncology although the onset of multidrug resistance (MDR) in neoplastic cells often leads to chemotherapy failure. Better understanding of the cellular mechanisms that circumvent chemotherapy efficacy is paramount. The aim of this study was to investigate the response of two canine mammary tumour cell lines, CIPp from a primary tumour and CIPm, from its lymph node metastasis, to exposure to EC50(20h) DOX at 12, 24 and 48 h of treatment. We assessed the uptake and subcellular distribution of DOX, the expression and function of P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP), two important MDR mediators. To better understand this phenomenon the effects of DOX on the cell cycle and Ki67 cell proliferation index and the expression of p53 and telomerase reverse transcriptase (TERT) were also evaluated by immunocytochemistry (ICC). Results Both cell lines were able to uptake DOX within the nucleus at 3 h treatment while at 48 h DOX was absent from the intracellular compartment (assessed by fluorescence microscope) in all the surviving cells. CIPm, originated from the metastatic tumour, were more efficient in extruding P-gp substrates. By ICC and qRT-PCR an overall increase in both P-gp and BCRP were observed at 48 h of EC50(20h) DOX treatment in both cell lines and were associated with a striking increase in the percentage of p53 and TERT expressing cells by ICC. The cell proliferation fraction was decreased at 48 h in both cell lines and cell cycle analysis showed a DOX-induced arrest in the S phase for CIPp, while CIPm had an increase in cellular death without arrest. Both cells lines were therefore composed by a fraction of cells sensible to DOX that underwent apoptosis/necrosis. Conclusions DOX administration results in interlinked modifications in the cellular population including a substantial effect on the cell cycle, in particular arrest in the S phase for CIPp and the selection of a subpopulation of neoplastic cells bearing MDR phenotype characterized by P-gp and BCRP expression, TERT activation, p53 accumulation and decrease in the proliferating fraction. Important information is given for understanding the dynamic and mechanisms of the onset of drug resistance in a neoplastic cell population.

Functional Expression of Multidrug-Resistance (MDR) Transporters in Developing Human Fetal Brain Endothelial Cells

“…This is in contrast to what was observed in histological sections of brain microvessels, where the majority of cells expressing vWF co-stained with P-gp or BCRP. It has been reported that P-gp and BCRP levels are linked to cell cycle and p53 expression [ 54 , 55 ]. It is possible that in vitro conditions may impose greater differences in cell cycle phases compared to the in vivo conditions and may, therefore, explain the lack of P-gp and BCRP staining in a small number of vWF-positive cells.…”

The Effects of Bergamot Polyphenolic Fraction, Cynara cardunculus, and Olea europea L. Extract on Doxorubicin-Induced Cardiotoxicity

“…This interpretation was demonstrated by the silencing of ATF6, as shutdown of UPR activation led to a drastic increase in DOXO-induced damage. A potentially protective role of the UPR has been widely reported in the scientific literature [ 82 , 83 , 84 , 85 ].…”

Adaptation of the gut holobiont to malnutrition during mouse pregnancy depends on the type of nutritional adversity

“…There is limited information demonstrating direct regulation of MDR transporters by nutrients. However, MDRs do interact with a number of substrates which may be derived directly from the diet, and or/dietary components may influence the production/levels of substrates and other molecules that interact directly with MDRs, as seen with inflammation (and thus, metainflammation)[22], and cell cycle stage and p53 expression[51, 52]. To address this, we first explored whether and how maternal gut morphology adapts to the spectrum of malnutrition, as intestinal architecture and morphology may influence cellular function.…”