Retinoic acid negatively regulates β4 integrin expression and suppresses the malignant phenotype in a Lewis lung carcinoma cell line

Abstract

Retinoic acid (RA) is a potent inhibitor of the malignant phenotype and of tumour cell growth. We observed that in vitro RA treatment of a highly metastatic lung carcinoma cell line (C87) induced a marked reduction in the amount of the beta 4 integrin subunit. The downregulation of this adhesion molecule was assessed by immunofluorescence, immunoprecipitation, and northern analysis. In order to investigate the effects of RA on the malignant phenotype in C87 cells we performed morphological and functional analysis after RA treatment. We found that RA was able to produce marked changes in C87 cell shape, increasing the number of flat cells (90% of the total cell population), and significantly inhibiting the malignant and invasive phenotype of C87 cells. RA treatment suppressed their clonogenic potential in soft agar (control, 20 +/- 5; RA, 0), and strongly reduced their chemotactic and chemoinvasive capacity (chemotaxis: control, 231 +/- 5; RA, 28 +/- 0; chemoinvasion: control, 132 +/- 11; RA = 2 +/- 1). FACS analysis and cell count, however, indicated that RA reduced the growth of C87 cells only partially. After 72 h of treatment we observed only a 10% reduction in the S phase fraction of the cell population. Finally, the reduced lung colony-forming ability, observed after i.v. injection of RA-treated cells (lung foci/animal: RA-treated cells, 1 +/- 0.1; untreated, 8.5 +/- 0.8), further supports the conclusion that in this murine lung carcinoma cell line a marked reduction in the expression of the beta 4 integrin subunit is associated with a marked inhibition of the malignant phenotype.

Interaction of GRASP, a Protein encoded by a Novel Retinoic Acid-induced Gene, with Members of the Cytohesin Family of Guanine Nucleotide Exchange Factors

“…If GRASP, or a GRASP-like protein, acting through its alanine/proline-rich region and/or PDZ domain, associates with integrin receptors and/or associated proteins, it is conceivable that recruitment of cytohesin family members to this locus may similarly enhance the avidity of LFA-1 for ICAM-1. Such speculation would be consistent with previous studies demonstrating that treatment of various cell types with RA results in modulation of integrin adhesion (81)(82)(83)(84)(85)(86). For example, Katagiri and co-workers (87) have shown that retinoic acid potentiates cellular adhesion and aggregation mediated by LFA-1 and ICAM-1 in HL-60 cells undergoing neutrophilic differentiation.…”

Activation of the E-cadherin/catenin complex in human MCF-7 breast cancer cells by all-trans-retinoic acid

“…AI-trans-rinoic acid activates E-cadherin function SJ Vermeulen et al cribed for the decrease in B 16 melanoma cell aggregation (Edward et al, 1992) and for down-regulation of P4 integrins in LL4 cells (Gaetano et al, 1994). This need may be ascribed to the presence of serum in the culture medium and of albumin in the salt solution used for the aggregation assay (see Materials and methods).…”

Expression of the β4 integrin subunit in the mouse heart during embryonic development: Retinoic acid advances β4 expression

“…In F9 mouse teratocarcinoma cells, laminin and fibronectin expression was upregulated upon RA exposure (Hierck et al, 1993;Huang and Chakrabarty, 1994;Ross et al, 1994). Integrin subunits (al, a5,a6, av, pl, 03) are usually upregulated except that p4 is downregulated in lung carcinomas (Dedhar et al, 1991;Defilippi et al, 1991;Gaetano et al, 1994;Ross et al, 1994). In vivo, both lack and excess of retinol and its active metabolites can cause congenital malformations, although the mechanisms might differ.…”

“…Later, keratins, the intermediate filaments of epithelial cells, were shown to be upregulated by RA (Kim, 1992) as is the case for laminin, the major component of all basement membranes (Vasios et al, 1989;Vuolteenaho et al, 1990;Hierck et al, 1993;Huang and Chakrabarty, 1994;Ross et al, 1994). While in vitro data show that expression of some integrins is under RA control as well (Dedhar et al, 1991;Defilippi et al, 1991;Gaetano et al, 1994;Ross et al, 19941, and a6p4 is a major component of hemidesmosomes, linked to the intermediate filament network, we decided to study the expression of the p4 integrin subunit during normal and FtA induced abnormal development, with special emphasis on the heart.…”