KAT8/SIRT7-mediated Fascin-K41 acetylation/deacetylation regulates tumor metastasis in esophageal squamous cell carcinoma.

Fascin actin-bundling protein 1 (Fascin) is highly expressed in a variety of cancers, including esophageal squamous cell carcinoma (ESCC), working as an important oncogenic protein and promoting the migration and invasion of cancer cells by bundling F-actin to facilitate the formation of filopodia and invadopodia. However, it is not clear how exactly the function of Fascin is regulated by acetylation in cancer cells. Here, in ESCC cells, the histone acetyltransferase KAT8 catalyzed Fascin lysine 41 (K41) acetylation, to inhibit Fascin-mediated F-actin bundling and the formation of filopodia and invadopodia. Furthermore, NAD-dependent protein deacetylase sirtuin (SIRT) 7-mediated deacetylation of Fascin-K41 enhances the formation of filopodia and invadopodia, which promotes the migration and invasion of ESCC cells. Clinically, the analysis of cancer and adjacent tissue samples from patients with ESCC showed that Fascin-K41 acetylation was lower in the cancer tissue of patients with lymph node metastasis than in that of patients without lymph node metastasis, and low levels of Fascin-K41 acetylation were associated with a poorer prognosis in patients with ESCC. Importantly, K41 acetylation significantly blocked NP-G2-044, one of the Fascin inhibitors currently being clinically evaluated, suggesting that NP-G2-044 may be more suitable for patients with low levels of Fascin-K41 acetylation, but not suitable for patients with high levels of Fascin-K41 acetylation. © 2024 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

AKT serine/threonine kinase 2-mediated phosphorylation of fascin threonine 403 regulates esophageal cancer progression.

Fascin is the main actin-bundling protein in filopodia and is highly expressed in metastatic tumor cells. The overexpression of Fascin has been associated with poor clinical prognosis and metastatic progression. Post-translational modifications of Fascin, such as phosphorylation, can affect the proliferation and invasion of tumor cells by regulating the actin-bundling activity of Fascin. However, the phosphorylation sites of Fascin and their corresponding kinases require further exploration. In the current study, we identified novel phosphorylation of Fascin Threonine 403 (Fascin-T403) mediated by AKT serine/threonine kinase 2 (AKT2), which was studied using mass spectrometry data from esophageal cancer tissues (iProX database: IPX0002501000). A molecular dynamics simulation revealed that Fascin-Threonine 403 phosphorylation (Fascin-T403D) had a distinct spatial structure and correlation of amino acid residues, which was different from that of the wild type (Fascin-WT). Low-speed centrifugation assay results showed that Fascin-T403D affected actin cross-linking. To investigate whether Fascin-T403D affected the function of esophageal cancer cells, either Fascin-WT or Fascin-T403D were rescued in Fascin-knockout or siRNA cell lines. We observed that Fascin-T403D could suppress the biological behavior of esophageal cancer cells, including filopodia formation, cell proliferation, and migration. Co-immunoprecipitation (Co-IP) and Duolink in situ proximity ligation assay (PLA) were performed to measure the interaction between Fascin and AKT2. Using in vitro and in vivo kinase assays, we confirmed that AKT2, but not AKT1 or AKT3, is an upstream kinase of Fascin Threonine 403. Taken together, the AKT2-catalyzed phosphorylation of Fascin Threonine 403 suppressed esophageal cancer cell behavior, actin-bundling activity, and filopodia formation.

P300/CBP-associated factor (PCAF)-mediated acetylation of Fascin at lysine 471 inhibits its actin-bundling activity and tumor metastasis in esophageal cancer.

BACKGROUND: Fascin is crucial for cancer cell filopodium formation and tumor metastasis, and is functionally regulated by post-translational modifications. However, whether and how Fascin is regulated by acetylation remains unclear. This study explored the regulation of Fascin acetylation and its corresponding roles in filopodium formation and tumor metastasis. METHODS: Immunoprecipitation and glutathione-S-transferase pull-down assays were performed to examine the interaction between Fascin and acetyltransferase P300/CBP-associated factor (PCAF), and immunofluorescence was used to investigate their colocalization. An in vitro acetylation assay was performed to identify Fascin acetylation sites by using mass spectrometry. A specific antibody against acetylated Fascin was generated and used to detect the PCAF-mediated Fascin acetylation in esophageal squamous cell carcinoma (ESCC) cells using Western blotting by overexpressing and knocking down PCAF expression. An in vitro cell migration assay was performed, and a xenograft model was established to study in vivo tumor metastasis. Live-cell imaging and fluorescence recovery after photobleaching were used to evaluate the function and dynamics of acetylated Fascin in filopodium formation. The clinical significance of acetylated Fascin and PCAF in ESCC was evaluated using immunohistochemistry. RESULTS: Fascin directly interacted and colocalized with PCAF in the cytoplasm and was acetylated at lysine 471 (K471) by PCAF. Using the specific anti-AcK471-Fascin antibody, Fascin was found to be acetylated in ESCC cells, and the acetylation level was consequently increased after PCAF overexpression and decreased after PCAF knockdown. Functionally, Fascin-K471 acetylation markedly suppressed in vitro ESCC cell migration and in vivo tumor metastasis, whereas Fascin-K471 deacetylation exhibited a potent oncogenic function. Moreover, Fascin-K471 acetylation reduced filopodial length and density, and lifespan of ESCC cells, while its deacetylation produced the opposite effect. In the filipodium shaft, K471-acetylated Fascin displayed rapid dynamic exchange, suggesting that it remained in its monomeric form owing to its weakened actin-bundling activity. Clinically, high levels of AcK471-Fascin in ESCC tissues were strongly associated with prolonged overall survival and disease-free survival of ESCC patients. CONCLUSIONS: Fascin interacts directly with PCAF and is acetylated at lysine 471 in ESCC cells. Fascin-K471 acetylation suppressed ESCC cell migration and tumor metastasis by reducing filopodium formation through the impairment of its actin-bundling activity.