ARHGEF19 interacts with BRAF to activate MAPK signaling during the tumorigenesis of non‐small cell lung cancer

Abstract

Rho guanine nucleotide exchange factors (RhoGEFs) are proteins that activate Rho GTPases in response to extracellular stimuli and regulate various biologic processes. ARHGEF19, one of RhoGEFs, was reported to activate RhoA in the Wnt-PCP pathway controlling convergent extension in Xenopus gastrulation. The goal of our study was to identify the role and molecular mechanisms of ARHGEF19 in the tumorigenesis of non-small cell lung cancer (NSCLC). ARHGEF19 expression was significantly elevated in NSCLC tissues, and ARHGEF19 levels were significantly associated with lymph node status, distant metastasis and TNM stage; Patients with high ARHGEF19 levels had poor overall survival (OS) and progression-free survival (PFS). Our investigations revealed that ARHGEF19 overexpression promoted the cell proliferation, invasion and metastasis of lung cancer cells, whereas knockdown of this gene inhibited these processes. Mechanistically, ARHGEF19 activated the mitogen-activated protein kinase (MAPK) pathway in a RhoA-independent manner: ARHGEF19 interacted with BRAF and facilitated the phosphorylation of its downstream kinase MEK1/2; both the Dbl homology (DH) and Pleckstrin homology (PH) domains of ARHGEF19 were indispensable for the phosphorylation of MEK1/2. Furthermore, downregulation of miR-29b was likely responsible for the increased expression of ARHGEF19 in lung cancer tissues and, consequently, the abnormal activation of MAPK signaling. These findings suggest that ARHGEF19 upregulation, due to the low expression of miR-29 in NSCLC tissues, may play a crucial role in NSCLC tumorigenesis by activating MAPK signaling. ARHGEF19 could serve as a negative prognostic marker as well as a therapeutic target for NSCLC patients.

Molecular characterization and integrative genomic analysis of a panel of newly established penile cancer cell lines

“…Cell invasion was tested using a Transwell assay 46 , 47 . Briefly, 2 × 10 5 cells in 200 μL serum-free or complete medium were seeded into the Boyden chamber with Matrigel (8-μm pore; BD Falcon, USA).…”

Emerging Roles of Ephexins in Physiology and Disease

“…For instance, various cancer tissues and cell lines show elevated levels of Ephexin2, which results in the increased activity of RhoA causing higher cancer proliferation, migration, and invasion. The downregulated levels of Ephexin2 by miR-503 have an inhibitory effect on cancer metastasis in hepatocellular carcinoma model and miR-29b, which downregulates the levels of Ephexin2, is decreased in non-small cell lung cancer (NSCLC) [39,40]. Interestingly, the roles of Ephexin2 during pronephric tubulogenesis and in the cancer are relevant to the high expression levels of Ephexin2 in the kidney, as well as the liver and lung.…”

“…For example, it has been reported that they regulate angiogenesis [34], efferocytosis, a type of phagocytosis to clear apoptotic cells in the body [35,36,37], and vascular muscle contractility [18]. Moreover, aberrant expression or function of Ephexins are related to various types of cancer [38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53]. Thus, the roles of Ephexins are not limited to the nervous system.…”

Elevated serum LAMC2 is associated with lymph node metastasis and predicts poor prognosis in penile squamous cell carcinoma

“…Stable cell lines with overexpressing or silenced LAMC2 were established according to the methods described previously. 31,32 Briefly, LAMC2 cDNA was cloned into the pCDH-EF1-CMV-MCS-T2A-Puro vector (System Biosciences, Palo Alto, CA, USA), and LAMC2 shRNAs (Table S3) were inserted into the pLko.1 vector (Sigma-Aldrich Co., St. Louis, MO, USA). Recombinant lentiviruses were packaged in 293T cells and used to construct the stable cell lines.…”

“…Male BALB/c nude mice (4-5 weeks old; SLRC Laboratory Animals, Shanghai, China) were used to generate an inguinal LN metastasis model, as described previously. 31 Two million cells were injected into the foot pads of the mice (n=10/group). The mice were killed after 10~12 weeks, and inguinal LNs were examined.…”