Establishment of an antibody specific for AMIGO2 improves immunohistochemical evaluation of liver metastases and clinical outcomes in patients with colorectal cancer

AMIGO2 enhances the invasive potential of colorectal cancer by inducing EMT

In our previous studies, we identified amphoterin-inducible gene and open reading frame 2 (AMIGO2) as a driver gene for liver metastasis and found that AMIGO2 expression in cancer cells worsens the prognosis of patients with colorectal cancer (CRC). Epithelial-mesenchymal transition (EMT) is a trigger for CRC to acquire a malignant phenotype, such as invasive potential, leading to metastasis. However, the role of AMIGO2 expression in the invasive potential of CRC cells remains unclear. Thus, this study aimed to examine AMIGO2 expression and elucidate the mechanisms by which it induces EMT and promotes CRC invasion. Activation of the TGFβ/Smad signaling pathway was found involved in AMIGO2-induced EMT, and treatment with the TGFβ receptor inhibitor LY2109761 suppressed AMIGO2-induced EMT. Studies using CRC samples showed that AMIGO2 expression was highly upregulated in the invasive front, where AMIGO2 expression was localized to the nucleus and associated with EMT marker expression. These results suggest that the nuclear translocation of AMIGO2 induces EMT to promote CRC invasion by activating the TGFβ/Smad signaling pathway. Thus, AMIGO2 is an attractive therapeutic target for inhibiting EMT and metastatic CRC progression.

Role of AMIGO2 in cancer progression: Novel insights (Review)

Adhesion molecule with IgG-like domain 2 (AMIGO2) is a novel scaffold protein initially identified in cerebellar granule neurons, and inhibits apoptosis of neurons. It is also widely expressed in various malignant tumors, including gastric cancer, colorectal carcinoma, ovarian cancer, prostate cancer and melanoma. During the past decades, it has been revealed that AMIGO2 can act as an oncogene, participating in tumor occurrence and development, for example by inhibiting apoptosis, accelerating cell proliferation, migration and adhesion, and promoting tumor metastasis and drug resistance. The present review discusses the recent advancements regarding AMIGO2 in the field of cancer, emphasizing its related molecular mechanisms to identify novel therapeutic strategies targeting AMIGO2 for cancer treatment in the future.

AMIGO2 is involved in the spread of peritoneal metastasis in serous ovarian cancer via promoting adhesion to the peritoneal mesothelial cells

BACKGROUND

Amphoterin-induced gene and open reading frame 2 (AMIGO2) have been reported to be related to the prognosis of colorectal, gastric, and cervical cancer. However, their association with ovarian cancer remains unclear. This study aimed to elucidate the role of AMIGO2 in ovarian cancer.

METHODS

AMIGO2 expression was evaluated using immunohistochemistry in patients with ovarian serous carcinoma. We validated in vitro studies using four serous ovarian cancer cell lines and in vivo studies using a murine model.

RESULTS

The AMIGO2-high group had significantly shorter progression-free survival (PFS) than the AMIGO2-low group. The predictive index of the AMIGO2-high group was considerably higher than that of the AMIGO2-low group. The rate of complete cytoreductive surgery was lower in the AMIGO2-high group than in the AMIGO2-low group. Moreover, in vitro studies revealed that four serous ovarian cancer cell lines exhibited AMIGO2 expression and adhesion to mesothelial cells. Adhesion to mesothelial cells was attenuated by AMIGO2 knockdown in SKOV3 and SHIN3 cells. Furthermore, AMIGO2 downregulation in SKOV3 cells significantly suppressed peritoneal dissemination in the murine model.

CONCLUSION

These results suggest that high AMIGO2 expression in serous ovarian carcinoma cells contributes to a poor prognosis by promoting peritoneal metastasis through enhanced cell adhesion to mesothelial cells.

AMIGO2 expression as a predictor of recurrence in cervical cancer with intermediate risk

Patients with recurrent cervical cancer have limited treatment options and are often considered to be incurable. Since the expression of amphoterin-induced gene and open reading frame 2 (AMIGO2) in clinical samples is a prognostic factor for colorectal cancer and gastric cancer, the present aimed to elucidate whether it is also a prognostic factor for cervical cancer. Patients with primary cervical cancer who underwent radical hysterectomy or radical trachelectomy at our institution (Faculty of Medicine, Tottori University, Yonago, Japan) between September 2005 and October 2016 were retrospectively collected. Immunohistochemical analysis using a specific antibody against AMIGO2 was performed on 101 tumor samples, and the clinical characteristics, disease-free survival (DFS) and overall survival (OS) of the patients were examined. Patients in the AMIGO2-high group had a shorter 5-year DFS and OS than those in the AMIGO2-low group (P<0.001). Furthermore, AMIGO2 was an independent prognostic factor for DFS in multivariate analysis (P=0.0012). Patients in the AMIGO2-high group exhibited obvious recurrence compared with those in the AMIGO2-low group in the high-(P=0.03) and intermediate-risk groups (P=0.003). Positive lymph node metastasis, and parametrial, stromal and lymph vascular space invasion were significantly more common in AMIGO2-high patients. Taken together, AMIGO2 expression may be a predictive marker of recurrence for cervical cancer. In particular, it may be an indicator to determine the need for postoperative adjuvant therapy in intermediate-risk group patients.

A Novel Molecular Analysis Approach in Colorectal Cancer Suggests New Treatment Opportunities

Colorectal cancer (CRC) is a molecular and clinically heterogeneous disease. In 2015, the Colorectal Cancer Subtyping Consortium classified CRC into four consensus molecular subtypes (CMS), but these CMS have had little impact on clinical practice. The purpose of this study is to deepen the molecular characterization of CRC. A novel approach, based on probabilistic graphical models (PGM) and sparse k-means-consensus cluster layer analyses, was applied in order to functionally characterize CRC tumors. First, PGM was used to functionally characterize CRC, and then sparse k-means-consensus cluster was used to explore layers of biological information and establish classifications. To this aim, gene expression and clinical data of 805 CRC samples from three databases were analyzed. Three different layers based on biological features were identified: adhesion, immune, and molecular. The adhesion layer divided patients into high and low adhesion groups, with prognostic value. The immune layer divided patients into immune-high and immune-low groups, according to the expression of immune-related genes. The molecular layer established four molecular groups related to stem cells, metabolism, the Wnt signaling pathway, and extracellular functions. Immune-high patients, with higher expression of immune-related genes and genes involved in the viral mimicry response, may benefit from immunotherapy and viral mimicry-related therapies. Additionally, several possible therapeutic targets have been identified in each molecular group. Therefore, this improved CRC classification could be useful in searching for new therapeutic targets and specific therapeutic strategies in CRC disease.

Liver Metastasis Formation Is Defined by AMIGO2 Expression via Adhesion to Hepatic Endothelial Cells in Human Gastric and Colorectal Cancer Cells

The adhesion of circulating cancer cells to vascular endothelial cells is an initial and critical step in distant metastases. Amphoterin-induced gene and open reading frame 2 (AMIGO2) was found to regulate tumor cell adhesion to hepatic endothelial cells and act as a driver gene for liver metastasis in mouse cell lines. However, whether the role of AMIGO2 observed in mouse tumor cells can be extrapolated to human cancer cells in vivo has not been verified. In this study, AMIGO2 expression in various human gastric and colorectal cancer cells was found to be closely associated with their adhesion to human hepatic sinusoidal endothelial cells (HHSECs). Constitutive AMIGO2-knockdown clones of human gastric (MKN-45) and colorectal cancer cell lines (DLD-1) were established to examine whether AMIGO2 expression in cancer cells is involved in the adhesion to HHSECs in vitro and the formation of liver metastasis in vivo. All AMIGO2-knockdown cells showed significantly attenuated adhesion to HHSECs. In vivo analysis revealed that intrasplenic inoculation of AMIGO2-knockdown clones could engraft in the spleen but significantly suppressed liver metastasis in nude mice. This study demonstrated that the role of AMIGO2 as a driver gene of liver metastasis in mouse tumor cells can be extrapolated to human cancer cells.

The impact of AMIGO2 on prognosis and hepatic metastasis in gastric cancer patients

BACKGROUND

Gastric cancer (GC) is one of the most common malignancies, and the liver is the most common site of hematogenous metastasis of GC. AMIGO2 is a type I transmembrane protein that has been implicated in tumour cell adhesion in adenocarcinomas; however, its importance in GC remains undetermined.

METHODS

We analyzed AMIGO2 expression by immunohistochemistry using the specific monoclonal antibody for human AMIGO2 in 128 patients who underwent GC surgery to evaluate its relationship between various metastatic and clinical outcomes in GC.

RESULTS

Immunohistochemistry revealed that AMIGO2 expression was an independent prognostic factor for overall survival, disease-specific survival, and liver metastasis in GC patients.

CONCLUSIONS

This study showed that AMIGO2 is induced in GC tissues and can mediate hepatic metastasis. Determining AMIGO2 expression in GC will help predict patient prognosis and the incidence of liver metastasis.