All-trans retinoic acid (ATRA)-induced apoptosis is preceded by G1 arrest in human MCF-7 breast cancer cells

Abstract

In this study the effects of all-trans retinoic acid (ATRA) on cell cycle and apoptosis of MCF-7 human breast cancer cells were investigated to elucidate the mechanisms underlying the antineoplastic potential of this retinoid in breast cancer. The antiproliferative effect of ATRA was evaluated by DNA content measurements and dual-parameter flow cytometry of bromodeoxyuridine (BrdU) incorporation and of the expression of cell cycle-related proteins (Ki-67 as proliferation marker and statin as quiescence marker) vs DNA content. Apoptosis was also studied by flow cytometry of either DNA content or Annexin V labelling. After 10(-6) M ATRA treatment, the fraction of S-phase cells decreased significantly, and cells accumulated in the G0/G1 range of DNA contents. Dual-parameter flow cytograms showed a decrease in the percentage of Ki-67-labelled cells (after 10 days, only 20% of the cells were still positive for Ki-67 compared with 95% in controls), while the fraction of statin-positive cells increased slightly. From 3 days of treatment onwards, apoptosis was found to occur. These results show that ATRA-induced inhibition of MCF-7 cell growth is related to two mechanisms, i.e. the block of cell proliferation, mostly in a pre-S phase, and the induction of apoptosis. These results should be taken into account when attempting to design treatment programmes that associate ATRA with antineoplastic compounds of different cell cycle specificity.

Her2/neu induces all-transretinoic acid (ATRA) resistance in breast cancer cells

“…The main mechanism by which ATRA inhibits the proliferation of breast cancer cells is by inducing G1 cell cycle arrest (Wilcken et al, 1996;Toma et al, 1997Toma et al, , 1998Mangiarotti et al, 1998). Breast cancer cells became growth arrested when they were incubated with ATRA for 3 or more days.…”

RAR agonists stimulate SOX9 gene expression in breast cancer cell lines: evidence for a role in retinoid-mediated growth inhibition

“…Retinoid-sensitive breast cancer cells have been reported to exhibit a delay in the G0-G1 phase of cell cycle following treatment with RA or other RARagonists Mangiarotti et al, 1998;Offterdinger et al, 1998). To confirm this, T-47D cells were incubated with 1 mM RA for 48 h followed by flowcytometric analysis of propidium iodide stained cells.…”

“…Rb, cyclin D and E, cyclin dependent kinases 2, 4, and 6, and their inhibitors p15, p16, p21 and p27 have all been suggested as potential targets for retinoids in normal and malignant breast cells as well as other cell types that are sensitive to retinoidmediated growth inhibition (Langenfeld et al, 1996;Seewaldt et al, 1997b;Zhou et al, 1997). In addition to mediating cell cycle changes, apoptosis of retinoid responsive cells has been observed by several investigators (Jinno et al, 1999;Mangiarotti et al, 1998;Shao et al, 1995;Sheikh et al, 1995;Teixeira and Pratt, 1997). Despite the cloning and characterization of the RARs and RXRs, and study of the activities of a variety of retinoid receptor specific ligands in breast cancer cell lines (Arafa et al, 1996(Arafa et al, , 2000Desai et al, 2000;Gianni et al, 1996;Willhite et al, 1996), the fundamental mechanisms of retinoid-mediated growth inhibition remain poorly understood.…”

Aspirin induces cell death and caspase-dependent phosphatidylserine externalization in HT-29 human colon adenocarcinoma cells

“…Some cell types from caspase-3 knockout mice are incapable of DNA degradation, but display other hallmarks of apoptosis, like PS externalization (Woo et al, 1998). Furthermore, the MCF-7 breast carcinoma cell line, which does not express caspase-3 (Janicke et al, 1998;Zapata et al, 1998), undergoes apoptosis in the absence of DNA fragmentation (Oberhammer et al, 1993;Janicke et al, 1998), but showing PS externalization (Mangiarotti et al, 1998). Interestingly, MCF-7 cells treated with the NSAID sulindac show nuclear condensation without clear DNA ladder (Han et al, 1998).…”