Antiproliferative effects of sodium butyrate in adriamycin-sensitive and -resistant human cancer cell lines

The proliferation of the MCF7 and MCF7-A (adrlamyclnresistant) and KB-3-1 and KB-A (adrlamycln-resistant) cell lines was arrested by sodium butyrate (NaBut) at 1 mM or higher concentrations. In the MCF7 and MCF7-A cell lines, an accumulation In the d phase was observed, whereas the KB-3-1 and KB-A cell lines accumulated In both G1 and G2/M phases. The level of the mRNA coded by the ʼearly G1ʼ/gene c-myc was high In all these cell lines, and was only transiently decreased by NaBut treatment. The ʼlateʼ mRNA coding for the proliferating cell nuclear antigen (PCNA) was also strongly expressed In all the cell lines studied; Incubation with NaBut caused a decrease of the PCNA mRNA In the MCF7 and MCF7-A cells but not In the KB-3-1 and KB-A cells. The antl-oncoproteln p105RB was undetectable In the MCF7 and MCF7-A cells, while the KB-3-1 as well as KB-A cells contained a high level of this protein. Neither the content nor the apparent state of phosphorylatlon of the RB protein were affected by incubation (up to 48 h) with NaBut.