Contactin 1 knockdown in the hindbrain induces abnormal development of the trigeminal sensory nerve in Xenopus embryos

Aberrant early growth of individual trigeminal sensory and motor axons in a series of mouse genetic models of 22q11.2 deletion syndrome

We identified divergent modes of initial axon growth that prefigure disrupted differentiation of the trigeminal nerve (CN V), a cranial nerve essential for suckling, feeding and swallowing (S/F/S), a key innate behavior compromised in multiple genetic developmental disorders including DiGeorge/22q11.2 Deletion Syndrome (22q11.2 DS). We combined rapid in vivo labeling of single CN V axons in LgDel^+/− mouse embryos, a genomically accurate 22q11.2DS model, and 3D imaging to identify and quantify phenotypes that could not be resolved using existing methods. We assessed these phenotypes in three 22q11.2-related genotypes to determine whether individual CN V motor and sensory axons wander, branch and sprout aberrantly in register with altered anterior–posterior hindbrain patterning and gross morphological disruption of CN V seen in LgDel^+/−. In the additional 22q11.2-related genotypes: Tbx1^+/−, Ranbp1^−/−, Ranbp1^+/− and LgDel^+/−:Raldh2^+/−; axon phenotypes are seen when hindbrain patterning and CN V gross morphology is altered, but not when it is normal or restored toward WT. This disordered growth of CN V sensory and motor axons, whose appropriate targeting is critical for optimal S/F/S, may be an early, critical determinant of imprecise innervation leading to inefficient oropharyngeal function associated with 22q11.2 deletion from birth onward.

Expression and prognostic significance of contactin 1 in human hepatocellular carcinoma

Background

CNTN1, a member of the CNTN family of neural cell-recognition molecules, is involved in tumor invasion and metastasis. Although the expression of CNTN1 has been reported in several human malignancies, the expression of CNTN1 in hepatocellular carcinoma (HCC) and its correlation with prognosis remain unclear. The aim of this study was to evaluate the expression of CNTN1 and determine the clinicopathological parameters and prognostic value of CNTN1 in HCC patients.

Materials and methods

Quantitative real-time polymerase chain-reaction and Western blotting assays were performed to assess messenger RNA and protein levels of CNTN1 in 20 matched HCC specimens. The clinical and prognostic significance of CNTN1 in 90 cases of HCC was determined by immunohistochemistry.

Results

CNTN1 expression was higher in HCC compared to the expression found in adjacent tissues at both messenger RNA and protein levels (P<0.01). Notably, immunohistochemical results revealed that CNTN1 expression was significantly higher in HCC compared to adjacent tissues (54.4% vs 12.2%, P=0.01). Furthermore, positive CNTN1 expression was associated with tumor size, tumor capsulae, status of metastasis, and tumor–node–metastasis stage. Kaplan–Meier survival analysis showed that high CNTN1 was correlated with reduced overall survival (OS) rate (P<0.001) and disease-free survival (DFS) rate (P=0.001). Multivariate analysis identified CNTN1 as an independent poor prognostic factor of OS and DFS in HCC patients (P=0.007 and P=0.002, respectively).

Conclusion

Our results suggest that CNTN1 could play an important role in HCC and serve as an independent unfavorable prognostic factor for OS and DFS and a potential therapeutic target for HCC.

Roles of contactin-1 in solid tumors

The neural cell adhesion molecule contactin-1 (CNTN1), first identified as a member of the contactin subpopulation of the immunoglobulin superfamily, is associated with many other cell surface proteins expressed on a variety of neurocytes, contributing to their functions and maturation. It has been recently found that the abnormal expression of CNTN1 has a close correlation with tumor initiation, development, invasiveness, metastasis and prognosis. The acquired metastatic ability of malignant tumors is caused by a population of cancer cells with the capacities of invasiveness, metastasis, adherence and proliferation, in which abnormal gene expression may play an important role. This review focuses on the current advances in research of CNTN1 in the nerve system, and mainly in the malignant tumors, with an aim to provide new clues to clinical prevention, diagnosis and treatment of these malignancies.

Contactin-1 reduces E-cadherin expression via activating AKT in lung cancer

Contactin-1 has been shown to promote cancer metastasis. However, the underlying mechanisms remain unclear. We report here that knockdown of contactin-1 in A549 lung cancer cells reduced A549 cell invasion and the cell's ability to grow in soft agar without affecting cell proliferation. Reduction of contactin-1 resulted in upregulation of E-cadherin, consistent with E-cadherin being inhibitive of cancer cell invasion. In an effort to investigate the mechanisms whereby contactin-1 reduces E-cadherin expression, we observed that contactin-1 plays a role in AKT activation, as knockdown of contactin-1 attenuated AKT activation. Additionally, inhibition of AKT activation significantly enhanced E-cadherin expression, an observation that mimics the situation observed in contactin-1 knockdown, suggesting that activation of AKT plays a role in contactin-1-mediated downregulation of E-cadherin. In addition, we were able to show that knockdown of contactin-1 did not further reduce A549 cell's invasion ability, when AKT activation was inhibited by an AKT inhibitor. To further support our findings, we overexpressed CNTN-1 in two CNTN-1 null breast cancer cell lines expressing E-cadherin. Upon overexpression, CNTN-1 reduced E-cadherin levels in one cell line and increased AKT activation in the other. Furthermore, in our study of 63 primary lung cancers, we observed 65% of primary lung cancers being contactin-1 positive and in these carcinomas, 61% were E-cadherin negative. Collectively, we provide evidence that contactin-1 plays a role in the downregulation of E-cadherin in lung cancer and that AKT activation contributes to this process. In a study of mechanisms responsible for contactin-1 to activate AKT, we demonstrated that knockdown of CNTN-1 in A549 cells did not enhance PTEN expression but upregulated PHLPP2, a phosphatase that dephosphorylates AKT. These observations thus suggest that contactin-1 enhances AKT activation in part by preventing PHLPP2-mediated AKT dephosphrorylation.

Contactin-1 (CNTN-1) overexpression is correlated with advanced clinical stage and lymph node metastasis in oesophageal squamous cell carcinomas

OBJECTIVE

Oesophageal squamous cell carcinoma is one of the deadliest malignancies worldwide. Contactin-1, a neural adhesion molecule, is implicated in tumour invasion and metastasis. The purpose of this study was to investigate the expression of CNTN-1 in normal and cancerous oesophageal tissue, and the potential relevance to clinicopathological features.

METHODS

Thirty normal oesophageal tissue samples and 82 primary oesophageal squamous cell carcinoma tissue samples were included in this study. The expression levels of CNTN-1, VEGF-C and HIF-1α messenger RNA were determined using reverse transcriptase-polymerase chain reaction and quantitative real-time polymerase chain reaction. The expression of the CNTN-1 protein was measured using immunohistochemistry.

RESULTS

The expression of CNTN-1 messenger RNA was significantly increased in the tumour tissue compared with the normal oesophageal tissue (P=0.001). The oesophageal squamous cell carcinoma tissue consistently showed higher CNTN-1 protein levels. The CNTN-1 expression correlated with the oesophageal squamous cell carcinoma stage (P=0.006), lymph node metastasis (P=0.018) and lymphatic invasion (P=0.035). The messenger RNA level of CNTN-1 correlated significantly with those of VEGF-C and HIF-1α.

CONCLUSIONS

The expression of CNTN-1 is upregulated in the oesophageal squamous cell carcinoma tissue and related to stage, lymph node metastasis and lymphatic invasion. Thus, CNTN-1 may be involved in the progression and pathogenesis of oesophageal squamous cell carcinoma.

The cell adhesion molecule Tag1, transmembrane protein Stbm/Vangl2, and Lamininalpha1 exhibit genetic interactions during migration of facial branchiomotor neurons in zebrafish

Interactions between a neuron and its environment play a major role in neuronal migration. We show here that the cell adhesion molecule Transient Axonal Glycoprotein (Tag1) is necessary for the migration of the facial branchiomotor neurons (FBMNs) in the zebrafish hindbrain. In tag1 morphant embryos, FBMN migration is specifically blocked, with no effect on organization or patterning of other hindbrain neurons. Furthermore, using suboptimal morpholino doses and genetic mutants, we found that tag1, lamininalpha1 (lama1) and stbm, which encodes a transmembrane protein Vangl2, exhibit pairwise genetic interactions for FBMN migration. Using time-lapse analyses, we found that FBMNs are affected similarly in all three single morphant embryos, with an inability to extend protrusions in a specific direction, and resulting in the failure of caudal migration. These data suggest that tag1, lama1 and vangl2 participate in a common mechanism that integrates signaling between the FBMN and its environment to regulate migration.