Willing to Be Involved in Cancer

FERM domain-containing protein FRMD6 activates the mTOR signaling pathway and promotes lung cancer progression

FRMD6, a member of the 4.1 ezrin-radixin-moesin domain-containing protein family, has been reported to inhibit tumor progression in multiple cancers. Here, we demonstrate the involvement of FRMD6 in lung cancer progression. We find that FRMD6 is overexpressed in lung cancer tissues relative to in normal lung tissues. In addition, the enhanced expression of FRMD6 is associated with poor outcomes in patients with lung squamous cell carcinoma (n = 75, P = 0.0054) and lung adenocarcinoma (n = 94, P = 0.0330). Cell migration and proliferation in vitro and tumor formation in vivo are promoted by FRMD6 but are suppressed by the depletion of FRMD6. Mechanistically, FRMD6 interacts and colocalizes with mTOR and S6K, which are the key molecules of the mTOR signaling pathway. FRMD6 markedly enhances the interaction between mTOR and S6K, subsequently increasing the levels of endogenous pS6K and downstream pS6 in lung cancer cells. Furthermore, knocking out FRMD6 inhibits the activation of the mTOR signaling pathway in Frmd6-/- gene KO MEFs and mice. Altogether, our results show that FRMD6 contributes to lung cancer progression by activating the mTOR signaling pathway.

FERM domain-containing protein 6 exerts a tumor-inhibiting role in thyroid cancer by antagonizing oncogenic YAP1

The emerging role of FERM domain-containing protein 6 (FRMD6) in cancer progression has been revealed in several malignancies. However, its relevance on thyroid cancer is not well understood. This work evaluated the possible role and mechanism of FRMD6 in thyroid cancer. We demonstrated that FRMD6 expression was downregulated in thyroid cancer by analyzing the Cancer Genome Atlas data. Remarkable reductions in FRMD6 expression were also confirmed in the clinical specimens and cell lines of thyroid cancer. The upregulation of FRMD6 restrained the proliferation, epithelial-mesenchymal transition, and invasion of thyroid cancer. Moreover, FRMD6 overexpression significantly increased the apoptosis and cell cycle arrest. Further molecular research demonstrated that the overexpression of FRMD6 increased the phosphorylation levels of mammalian STE20-like protein kinase 1, large tumor suppressor 1, and Yes-associated protein 1 (YAP1) and prohibited the activation of YAP1. The re-expression of constitutively active YAP1 strikingly reversed FRMD6-induced tumor-inhibiting effects. Thyroid cancer cells overexpressing FRMD6 had a weakened ability to form xenograft tumors in vivo in nude mice. Overall, the overexpression of FRMD6 produces remarkable tumor-inhibiting effects in thyroid cancer by inhibiting oncogenic YAP1.

Willin/FRMD6: A Multi-Functional Neuronal Protein Associated with Alzheimer's Disease

The FERM domain-containing protein 6 (FRMD6), also known as Willin, is an upstream regulator of Hippo signaling that has recently been shown to modulate actin cytoskeleton dynamics and mechanical phenotype of neuronal cells through ERK signaling. Physiological functions of Willin/FRMD6 in the nervous system include neuronal differentiation, myelination, nerve injury repair, and vesicle exocytosis. The newly established neuronal role of Willin/FRMD6 is of particular interest given the mounting evidence suggesting a role for Willin/FRMD6 in Alzheimer's disease (AD), including a series of genome wide association studies that position Willin/FRMD6 as a novel AD risk gene. Here we describe recent findings regarding the role of Willin/FRMD6 in the nervous system and its actions in cellular perturbations related to the pathogenesis of AD.

FRMD6 has tumor suppressor functions in prostate cancer

Available tools for prostate cancer (PC) prognosis are suboptimal but may be improved by better knowledge about genes driving tumor aggressiveness. Here, we identified FRMD6 (FERM domain-containing protein 6) as an aberrantly hypermethylated and significantly downregulated gene in PC. Low FRMD6 expression was associated with postoperative biochemical recurrence in two large PC patient cohorts. In overexpression and CRISPR/Cas9 knockout experiments in PC cell lines, FRMD6 inhibited viability, proliferation, cell cycle progression, colony formation, 3D spheroid growth, and tumor xenograft growth in mice. Transcriptomic, proteomic, and phospho-proteomic profiling revealed enrichment of Hippo/YAP and c-MYC signaling upon FRMD6 knockout. Connectivity Map analysis and drug repurposing experiments identified pyroxamide as a new potential therapy for FRMD6 deficient PC cells. Finally, we established orthotropic Frmd6 and Pten, or Pten only (control) knockout in the ROSA26 mouse prostate. After 12 weeks, Frmd6/Pten double knockouts presented high-grade prostatic intraepithelial neoplasia (HG-PIN) and hyperproliferation, while Pten single-knockouts developed only regular PIN lesions and displayed lower proliferation. In conclusion, FRMD6 was identified as a novel tumor suppressor gene and prognostic biomarker candidate in PC.

Willin/FRMD6 Influences Mechanical Phenotype and Neuronal Differentiation in Mammalian Cells by Regulating ERK1/2 Activity

Willin/FRMD6 is part of a family of proteins with a 4.1 ezrin-radixin-moesin (FERM) domain. It has been identified as an upstream activator of the Hippo pathway and, when aberrant in its expression, is associated with human diseases and disorders. Even though Willin/FRMD6 was originally discovered in the rat sciatic nerve, most studies have focused on its functional roles in cells outside of the nervous system, where Willin/FRMD6 is involved in the formation of apical junctional cell-cell complexes and in regulating cell migration. Here, we investigate the biochemical and biophysical role of Willin/FRMD6 in neuronal cells, employing the commonly used SH-SY5Y neuronal model cell system and combining biochemical measurements with Elastic Resonator Interference Stress Micropscopy (ERISM). We present the first direct evidence that Willin/FRMD6 expression influences both the cell mechanical phenotype and neuronal differentiation. By investigating cells with increased and decreased Willin/FRMD6 expression levels, we show that Willin/FRMD6 not only affects proliferation and migration capacity of cells but also leads to changes in cell morphology and an enhanced formation of neurite-like membrane extensions. These changes were accompanied by alterations of biophysical parameters such as cell force, the organization of actin stress fibers and the formation of focal adhesions. At the biochemical level, changes in Willin/FRMD6 expression inversely affected the activity of the extracellular signal-regulated kinases (ERK) pathway and downstream transcriptional factor NeuroD1, which seems to prime SH-SY5Y cells for retinoic acid (RA)-induced neuronal differentiation.

MTA2 promotes HCC progression through repressing FRMD6, a key upstream component of hippo signaling pathway

Discerning oncogenic drivers from passengers remains a major effort in understanding of the essence of the initiation and development of hepatocellular carcinoma (HCC), the most common primary liver malignancy and the third leading cause of cancer mortality worldwide. Here we report that MTA2, Metastasis Associated 1 Family Member 2, is significantly up-regulated in HCC. We show that high level of MTA2 expression is strongly correlated with advanced pathological stages and poor overall survival of the patients. Genome-wide identification of the transcriptional targets of MTA2 by ChIP-seq indicates that MTA2 represses a cohort of genes including FRMD6 that are critically involved in the growth and mobility of HCC. We demonstrate that the MTA2 promotes the proliferation and metastasis of HCC in vitro and in vivo through suppressing Hippo signaling pathway. Together, these results reveal a key role for the MTA2-FRDM6-Hippo axis in human hepatocarcinogenesis.