Regulation of myc gene expression in HL-60 leukaemia cells by a vitamin D metabolite

Abstract

HL-60, a cell line established from a patient with promyelocytic leukaemia, responds to a variety of inducing agents by ceasing division and acquiring some of the characteristics of either granulocytes or monocytes. Among the agents so far tested, only a comparative few occur naturally in vertebrates and would appear to have significant clinical potential in the treatment of leukaemic patients. One of the most promising of these is the dihydroxymetabolite of vitamin D3, 1,25(OH)2D3. This compound circulates in normal man and has a major role in calcium homeostasis. Moreover, it has recently been reported that 1,25(OH)2D3 increases the survival time of mice injected with myeloid leukaemia cells. We and McCarthy et al. have previously shown that HL-60 cells respond to near physiological levels of 1,25(OH)2D3 by rapidly acquiring a number of monocyte-like features. Here we document that these phenotypic changes are preceded by a marked decrement in the expression of the c-myc oncogene. In fact, the diminution in the level of c-myc mRNA parallels the dose dependency and metabolite specificity shown by the various other indicators of phenotypic change. In addition, we demonstrate that removal of vitamin D3, after the onset of maturational change, results in the reappearance of elevated myc mRNA levels. We believe this to be the first demonstration of a sequential relationship between the application of an exogenous inducing agent, a reduction in myc mRNA levels and the development of characteristics associated with normal cell maturation.

Retinoblastoma protein-overexpressing HL60 cells resistant to 1,25-dihydroxyvitamin D3 display increased CDK2 and CDK6 activity and shortened G1 phase

“…For instance, 1,25D 3 has been shown to down-regulate the expression of the c-myc proto-oncogene (Reitsma et al, 1983;Brelvi and Studzinski, 1986) and up-regulate c-jun and c-fos genes (Muller et al, 1985;Kolla et al, 1994;Kovary and Bravo, 1991), apparently related to the antiproliferative and pro-di erentiation e ects of 1,25D 3 on these cells. Although it has been shown that these e ects are separable Studzinski et al, 1997), are associated with modulation of the expression of several other genes such as mad (Wang et al, 1997b) and p27 Kip1 1997a), and are believed to be mediated by the activation of the nuclear receptor VDR (Haussler and Norman, 1969;Holick et al, 1971), the details of how 1,25D 3 controls cell proliferation remain to be elucidated.…”

Sequences involved in accurate and efficient transcription of human c-myc genes microinjected into frog oocytes.

“…A variety of activation mechanisms of this gene have been found in various tumors (24), in sensitive response to mitogen treatment (7,19,23,31), and following in vitro-induced cell differentiation (7,37). Several possible control mechanisms of the normal c-myc gene involving a transcriptional repressor (26) or emphasizing the importance of RNA stability or turnover (4, 9, 10) have been proposed.…”

Characterization of a novel hexameric repeat DNA sequence in the promoter of the immediate early gene, IEX-1, that mediates 1α,25-dihydroxyvitamin D3-associated IEX-1 gene repression

“…Also, the proliferation of number of epithelially derived cancer cells (e.g., mammary, prostate and colon) is inhibited in culture by 1a,25(OH) 2 D 3 (Haussler et al, 1998). This e ect in neoplastic cells may be related to the reported ability of liganded VDR to arrest cells at the G 1 stage by in¯uencing cell cycle regulatory proteins, such as p21 and p27, to control cell growth factors such as c-myc (Reitsma et al, 1983;O'Connell and Simpson, 1995), c-fos (Candeliere et al, 1996) and IEX-1 (Kumar et al, 1998), or to elicit apoptosis by Figure 5 VDRE/RXRa heterodimer formation is required for the DNA-protein interaction. Electrophoretic mobility shift assay was performed using a nity puri®ed full-length human vitamin D receptor (hVDR) and human retinoic acid X receptor a (hRXRa) expressed in E. coli.…”

“…Vitamin D 3 is anti-proliferative and promotes di erentiation in several cell lines such as HL60 (Reitsma et al, 1983), neuroblastoma , osteoblast (Wu et al, 1997) and HaCaT (Haugen et al, 1996) cell lines. Vitamin D 3 appears to a ect dramatically the maturation and functions of certain normal and neoplastic epithelial cells (Berger et al, 1988;Giuliano et al, 1991;Mehta et al, 1997;Saunders et al, 1993;Peehl et al, 1994).…”