ALCAM Regulates Motility, Invasiveness, and Adherens Junction Formation in Uveal Melanoma Cells

Abstract

ALCAM, a member of the immunoglobulin superfamily, has been implicated in numerous developmental events and has been repeatedly identified as a marker for cancer metastasis. Previous studies addressing ALCAM’s role in cancer have, however, yielded conflicting results. Depending on the tumor cell type, ALCAM expression has been reported to be both positively and negatively correlated with cancer progression and metastasis in the literature. To better understand how ALCAM might regulate cancer cell behavior, we utilized a panel of defined uveal melanoma cell lines with high or low ALCAM levels, and directly tested the effects of manipulating these levels on cell motility, invasiveness, and adhesion using multiple assays. ALCAM expression was stably silenced by shRNA knockdown in a high-ALCAM cell line (MUM-2B); the resulting cells displayed reduced motility in gap-closure assays and a reduction in invasiveness as measured by a transwell migration assay. Immunostaining revealed that the silenced cells were defective in the formation of adherens junctions, at which ALCAM colocalizes with N-cadherin and ß-catenin in native cells. Additionally, we stably overexpressed ALCAM in a low-ALCAM cell line (MUM-2C); intriguingly, these cells did not exhibit any increase in motility or invasiveness, indicating that ALCAM is necessary but not sufficient to promote metastasis-associated cell behaviors. In these ALCAM-overexpressing cells, however, recruitment of ß-catenin and N-cadherin to adherens junctions was enhanced. These data confirm a previously suggested role for ALCAM in the regulation of adherens junctions, and also suggest a mechanism by which ALCAM might differentially enhance or decrease invasiveness, depending on the type of cadherin adhesion complexes present in tissues surrounding the primary tumor, and on the cadherin status of the tumor cells themselves.

ALCAM is a Novel Cytoplasmic Membrane Protein in TNF-α Stimulated Invasive Cholangiocarcinoma Cells

“…Likewise, they demonstrated that ALCAM was highly expressed on the surface of prostate stem/ progenitor and cancer initiating cells (Jiao et al, 2012). In melanoma, pancreatic-and prostate cancers, up-regulation of ALCAM is associated with invasion and metastasis (Jannie et al, 2012;Fujiwara et al, 2014;Hansen et al, 2014). Our findings support these previous studies -ALCAM up-regulated both mRNA and protein levels when the CAA cell line was induced to invasive character.…”

“…The location and increasing the expression of ALCAM in CCA cell line may suggest its roles in cell migration and invasion as found in other cancers (breast and pancreatic cancer) (Davies and Jiang, 2010;Fujiwara et al, 2014). In melanoma, silencing ALCAM expression in high-ALCAM expressed cell line a showed reduction of cell motility and invasiveness (Jannie et al, 2012). Moreover, blocking ALCAM with single-chain antibody inhibited invasiveness of breast cancer (Wiiger et al, 2010).…”

A self-renewing division of zebrafish Müller glial cells generates neuronal progenitors that require N-cadherin to regenerate retinal neurons

“…Although we have no functional data on the role of Alcama in retinal regeneration, its distribution along the radial Müller glial processes, which guide migration of rod precursors in the uninjured, growing fish retina (Raymond and Rivlin, 1987), suggests that Alcama-dependent adhesive interactions may mediate migration of progenitors in the neurogenic clusters. Interestingly, mammalian ALCAM also colocalizes with VE-and N-cadherin at lateral membrane domains in endothelial cell junctions (Ofori-Acquah et al, 2008); it is a marker for metastasis in human tumor cells, recruits N-cadherin and β-catenin to adherens junctions, and promotes motility in uveal melanoma cell lines (Jannie et al, 2012).…”

miR-214 Coordinates Melanoma Progression by Upregulating ALCAM through TFAP2 and miR-148b Downmodulation

“…Significantly, the fraction of ALCAM-positive lesions increases according to invasiveness (Clark level) and thickness (Breslow index) of the melanocytic tumor (8). It was shown that any interference with ALCAM function affects melanoma cell movement and invasion (9,10) and that ALCAM triggers MMP2 and MMP14 activity (11). However, it is still not known how ALCAM overexpression is induced in melanomas and how it coordinates metastasis formation.…”