LGR5 receptor promotes cell–cell adhesion in stem cells and colon cancer cells via the IQGAP1–Rac1 pathway

Carmon, Kendra S.; Gong, Xing; Yi, Jing; Wu, Ling; Thomas, Anthony; Moore, Catherine; Masuho, Ikuo; Timson, David J.; Martemyanov, Kirill A.; Liu, Qingyun J.

doi:10.1074/jbc.m117.786798

Cited by 65 publications

(66 citation statements)

References 58 publications

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“…We measured CK2 activity indirectly by using an antibody against the phospho-CK2 substrate (motif pS/pTDXE) to measure the amount of phosphorylated CK2 substrates. This method is widely used in literature to measure kinase activity, such as activity of the following kinases CK2 [ 16 , 49 , 50 , 51 , 52 ], AMPK [ 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ], AMT/ATR [ 64 , 65 , 66 , 67 , 68 , 69 , 70 ], PKA [ 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ], and PKC [ 77 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 ]. Both CK2 knockdown and CX-4945 treatment inhibited the proliferation of CCA cells.…”

Section: Discussionmentioning

confidence: 99%

CX-4945 Induces Methuosis in Cholangiocarcinoma Cell Lines by a CK2-Independent Mechanism

Lertsuwan

Sawasdichai

et al. 2018

Cancers

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Cholangiocarcinoma is a disease with a poor prognosis and increasing incidence and hence there is a pressing unmet clinical need for new adjuvant treatments. Protein kinase CK2 (previously casein kinase II) is a ubiquitously expressed protein kinase that is up-regulated in multiple cancer cell types. The inhibition of CK2 activity using CX-4945 (Silmitasertib) has been proposed as a novel treatment in multiple disease settings including cholangiocarcinoma. Here, we show that CX-4945 inhibited the proliferation of cholangiocarcinoma cell lines in vitro. Moreover, CX-4945 treatment induced the formation of cytosolic vacuoles in cholangiocarcinoma cell lines and other cancer cell lines. The vacuoles contained extracellular fluid and had neutral pH, features characteristic of methuosis. In contrast, simultaneous knockdown of both the α and α′ catalytic subunits of protein kinase CK2 using small interfering RNA (siRNA) had little or no effect on the proliferation of cholangiocarcinoma cell lines and failed to induce the vacuole formation. Surprisingly, low doses of CX-4945 increased the invasive properties of cholangiocarcinoma cells due to an upregulation of matrix metallopeptidase 7 (MMP-7), while the knockdown of CK2 inhibited cell invasion. Our data suggest that CX-4945 inhibits cell proliferation and induces cell death via CK2-independent pathways. Moreover, the increase in cell invasion brought about by CX-4945 treatment suggests that this drug might increase tumor invasion in clinical settings.

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Section: Discussionmentioning

confidence: 99%

CX-4945 Induces Methuosis in Cholangiocarcinoma Cell Lines by a CK2-Independent Mechanism

Lertsuwan

Sawasdichai

et al. 2018

Cancers

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“…LGR5 was reported to alter the actin cytoskeleton structure and increased cell-cell adhesion by coupling to the intracellular scaffold signalling protein. 28,31 The study suggested that the major function of LGR5 may be to promote strong intracellular adhesion among stem cells and to retain them within the crypt base to maintain homoeostasis in the intestinal epithelium. 31 Weakened adhesion between cancer cells may facilitate the formation of intraperitoneal-free cancer cells, which may lead to peritoneal metastasis.…”

Section: Discussionmentioning

confidence: 99%

“…28,31 The study suggested that the major function of LGR5 may be to promote strong intracellular adhesion among stem cells and to retain them within the crypt base to maintain homoeostasis in the intestinal epithelium. 31 Weakened adhesion between cancer cells may facilitate the formation of intraperitoneal-free cancer cells, which may lead to peritoneal metastasis. Hence, this finding may explain the potential of LGR-negative tumours to cause peritoneal metastasis.…”

Section: Discussionmentioning

confidence: 99%

LGR5 expression predicts peritoneal recurrence after curative resection of primary colon cancer

et al. 2019

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BACKGROUND: The aim of this study was to clarify whether a cancer stem cell marker could be an indicator of post-operative peritoneal recurrence of colon cancer. METHODS: Expression of four putative markers (CD133, CD44 variant 6, aldehyde dehydrogenase-1 and leucine-rich repeating G-protein-coupled receptor-5 (LGR5)) was evaluated immunohistochemically in primary tumour samples from 292 patients who underwent curative resection for non-metastasised pT4 colon cancer at the University of Tokyo Hospital between 1997 and 2015. RESULTS: Peritoneal recurrence was significantly higher in LGR5-negative cases (5-year cumulative incidence: 27.5% vs. 14.4%, p = 0.037). Multivariable analysis confirmed that negative LGR5 expression was an independent risk factor for peritoneal recurrence (hazard ratio (HR) 2.79, p = 0.005) in addition to poor differentiation, positive lymph node metastasis, preoperative carcinoembryonic antigen > 5 ng/mL and anastomotic leakage. The addition of LGR5 significantly improved the predictive value of the multivariable model (net reclassification improvement: 0.186, p = 0.028: integrated discrimination improvement: 0.047, p = 0.008). CONCLUSIONS: Negative LGR5 expression was a significant predictor of peritoneal recurrence in patients with pT4 colon cancer. Therefore, LGR5 might be a promising biomarker to identify patients at high risk of post-operative peritoneal metastasis.

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“…GPR56 has been shown to induce activation of the small GTPase RhoA mediated through Gα12/13 to promote cell adhesion (13,20,(24)(25)(26). To examine if mutant GPR56 STP was fully functional, we utilized a GTPase pulldown assay that employs the Rho binding domain of the Rho effector, Rhotekin.…”

Section: Gpr56 Overexpression Activates Srf-re Independent Of the Stpmentioning

confidence: 99%

“…GPR56 has been shown to interact with proteins such as collagen III (24), transglutaminase 2 (TG2) (17), and progastrin (16); however receptor-specific ligands have yet to be fully validated. Several studies have established that GPR56 is coupled to the Gα12/13 class of heterotrimeric G-proteins to promote RhoA activation (13,22,(24)(25)(26). GPR56 overexpression has been shown to activate various signaling pathway response elements, including serum response element (SRE) and serum response factor response element (SRF-RE) that are likely regulated downstream of RhoA (20,21,25).…”

Section: Introductionmentioning

confidence: 99%

Anti-GPR56 monoclonal antibody potentiates GPR56-mediated Src-Fak signaling to modulate cell adhesion

Chatterjee

Zhang

Posey

et al. 2020

Preprint

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GPR56, also known as ADGRG1, is a member of the adhesion G protein-coupled receptor (aGPCR) family shown to play important roles in cell adhesion, brain development, immune system function, and tumorigenesis. GPR56 is upregulated in colorectal cancer and high expression correlates with poor prognosis. Several studies have shown that GPR56 couples to the Gα12/13 class of heterotrimeric G-proteins to promote RhoA activation. However, due to its structural complexity and lack of a high affinity receptorspecific ligand, the complete GPR56 signaling mechanism still remains largely unknown. To delineate the activation mechanism and intracellular signaling functions of GPR56, we generated a monoclonal antibody (mAb) which binds GPR56 with high affinity and specificity to the extracellular domain (ECD). We show that overexpression of GPR56 in 293T cells lead to increased phosphorylation of Src, Fak, and paxillin adhesion proteins and activation of the Gα12/13-RhoA-mediated serum response factor (SRF) pathway. Treatment of cells with anti-GPR56 mAb potentiated Src-Fak phosphorylation, RhoA-SRF signaling, and cell adhesion. Consistently, knockdown of GPR56 in colorectal cancer cells decreased Src-Fak pathway phosphorylation and cell adhesion. Interestingly, GPR56-mediated activation of Src-Fak phosphorylation occurred independent of RhoA, yet mAb-induced potentiation of RhoA-SRF signaling was Srcdependent. Furthermore, we show that the Serine-Threonine-Proline-rich (STP) region of the ECD of GPR56 was not essential for mAb binding, yet was required for activation of Src-Fak signaling. These data support a new ECD-dependent mechanism by which GPR56 functions to regulate cell adhesion through activation of Src-Fak signaling.

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LGR5 receptor promotes cell–cell adhesion in stem cells and colon cancer cells via the IQGAP1–Rac1 pathway

Cited by 65 publications

References 58 publications

CX-4945 Induces Methuosis in Cholangiocarcinoma Cell Lines by a CK2-Independent Mechanism

CX-4945 Induces Methuosis in Cholangiocarcinoma Cell Lines by a CK2-Independent Mechanism

LGR5 expression predicts peritoneal recurrence after curative resection of primary colon cancer

Anti-GPR56 monoclonal antibody potentiates GPR56-mediated Src-Fak signaling to modulate cell adhesion

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