SILAC identifies LAD1 as a filamin-binding regulator of actin dynamics in response to EGF and a marker of aggressive breast tumors

Abstract

Mutations mimicking growth factor-induced proliferation and motility characterize aggressive subtypes of mammary tumors. To unravel currently unknown players in these processes, we performed phosphoproteomic analysis on untransformed mammary epithelial cells (MCF10A) that were stimulated in culture with epidermal growth factor (EGF). We identified ladinin-1 (LAD1), a largely uncharacterized protein to date, as a phosphorylation-regulated mediator of the EGF-to-ERK pathway. Further experiments revealed that LAD1 mediated the proliferation and migration of mammary cells. LAD1 was transcriptionally induced, phosphorylated, and partly colocalized with actin stress fibers in response to EGF. Yeast two-hybrid, proximity ligation, and coimmunoprecipitation assays revealed that LAD1 bound to actin-cross-linking proteins called filamins. Cosedimentation analyses indicated that LAD1 played a role in actin dynamics, probably in collaboration with the scaffold protein 14-3-3σ (also called SFN). Depletion of LAD1 decreased the expression of transcripts associated with cell survival and inhibited the growth of mammary xenografts in an animal model. Furthermore, LAD1 predicts poor patient prognosis and is highly expressed in aggressive subtypes of breast cancer characterized as integrative clusters 5 and 10, which partly correspond to triple-negative and HER2-positive tumors. Thus, these findings reveal a cytoskeletal component that is critically involved in cell migration and the acquisition of oncogenic attributes in human mammary tumors.

Nongenic cancer-risk SNPs affect oncogenes, tumour-suppressor genes, and immune function

“…Most of these genes have been shown to be dysregulated in breast cancer or during epithelial-mesenchymal transition. Indeed, LAD1 has been associated with aggressive breast tumours, 41 COL17A1 is underexpressed in breast cancer and overexpressed in head and neck squamous cell carcinoma, lung squamous cell carcinoma and lung adenocarcinoma 42 and FERMT1 is a known mediator of epithelial-mesenchymal transition in colon cancer. 43 Cancer-risk SNPs preferentially target cancer genes We expected that cancer-risk SNPs might be preferentially associated with genes known to be involved in cancer development and progression.…”

Chemotaxis Model for Breast Cancer Cells Based on Signal/Noise Ratio

“…This study is primarily focused on chemotaxis of a metastatic breast cancer cell, MDA-MB-231, under chemotactic EGF gradients. Although the effects of EGF has been investigated extensively (38,39), multiple facets of EGF still continue to be identified (40)(41)(42)(43). EGF promotes actin nucleation for Mena invasive-expressed cells (40) and regulates intracellular mechanical responses related to ladinin-1 (41,42).…”

“…Although the effects of EGF has been investigated extensively (38,39), multiple facets of EGF still continue to be identified (40)(41)(42)(43). EGF promotes actin nucleation for Mena invasive-expressed cells (40) and regulates intracellular mechanical responses related to ladinin-1 (41,42). Moreover, breast cancer cells within hydrogels exhibit different responses to EGF gradients and EGF receptor (EGFR) inhibitors depending upon cell types (43).…”

PROM1 and PROM2 expression differentially modulates clinical prognosis of cancer: a multiomics analysis

“…7b). Previous studies have reported that LAD1, C1ORF106, PVRL4, and KCNK5 are upregulated in cancer cells [82][83][84][85]. Furthermore, LAD1 has been reported as a filament-binding regulator and also regulates EGF signaling-mediated breast cancer tumorigenesis [82].…”