Identification of invasion specific splice variants of the cytoskeletal protein Mena present in mammary tumor cells during invasion in vivo

Abstract

We have studied the gene expression pattern of invasive primary mammary tumor cells using a unique in vivo invasion assay that isolates the invasive tumor cells by chemotaxis. One of the genes upregulated in the invasive tumor cells is Mena, an actin binding protein involved in the regulation of cell motility. There are multiple known splice variants of Mena accounted for by four alternatively included exons, +, ++, +++ and 11a. Using the in vivo invasion assay in rats and

Splicing program of human MENA produces a previously undescribed isoform associated with invasive, mesenchymal-like breast tumors

“…However, our data that the presence of hMENA 11a (ESRP1 induced) reduces the number and the length of filopodia projecting into the gel in 3D cultures (Fig. 4), is consistent with the hypothesis that the 21-aa insertion of the 11a exon, influences the ability of the Ena/VASP tetramer to promote filopodia formation and extension (11). In a xenograft rodent mammary cancer model, the invasive cancer cells showed a decrease of Mena 11a and an increase of Mena INV isoform expression (11), reminiscent of our data.…”

“…S2A). Given the data in rodent models linking Mena splicing with mammary tumor cell invasion and migration (11,12), we performed isoform-specific overexpression and hMENA siRNA experiments to evaluate the role of alternative splicing of hMENA in human breast cancer invasion and progression. Transfection of hMENAΔv6 into BT549, MDA-MB-231, and DAL cells appreciably increased their invasiveness (Fig.…”

“…The MENA gene encodes the 570-aa hMENA protein and different alternative splicing-derived isoforms, often expressed in a tissue-specific manner, have been reported in human (8,9) and mouse (1,10,11). The neuronal variant is characterized by an extended exon 6 (1,8), the spleen-specific variant lacks the proline-rich region (10), and an invasion-specific splice variant (MENA INV ), with an additional exon just after the EVH1 domain, has been shown to regulate chemotaxis in mouse and rat mammary tumor cells (12).…”

Overexpression of human ortholog of mammalian enabled (hMena) is associated with the expression of mutant p53 protein in human breast cancers

“…Our results suggest that hMena may augment the invasive capacity of cancer cells. Furthermore, Philippar et al reported that Mena and its isoform MenaINV can promote carcinoma cell motility and invasiveness in vivo and in vitro, and increase lung metastasis by potentiating EGF-induced membrane protrusion and increasing the matrix degradation activity of tumor cells (21,22). These reports are consistent with our previous results, and we speculate that our immunohistochemical analysis partly detected the invasive isoform of hMena.…”

Molecular insights on context-specific role of profilin-1 in cell migration

“…Lpd plays an important role in membrane protrusion through downstream action of Ena/VASP, 33,78 and among the different Ena/VASP proteins, at least, Mena has been shown to be a critical player in breast cancer invasion and metastasis. [79][80][81][82][83] Thus, controlling Lpd-Ena/VASP recruitment to the leading edge clearly seems to be an attractive mechanism to regulate breast cancer cell motility which Pfn1-deficient condition takes advantage of.…”