Expression of LRIG proteins as possible prognostic factors in primary vaginal carcinoma

Immunoreactivity of LMO7 and other molecular markers as potential prognostic factors in oropharyngeal squamous cell carcinoma

BACKGROUND

Despite the better prognosis associated with human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC), some patients experience relapse and succumb to the disease; thus, there is a need for biomarkers identifying these patients for intensified treatment. Leucine-rich repeats and immunoglobulin-like domain (LRIG) protein 1 is a negative regulator of receptor tyrosine kinase signaling and a positive prognostic factor in OPSCC. Studies indicate that LRIG1 interacts with the LIM domain 7 protein (LMO7), a stabilizer of adherence junctions. Its role in OPSCC has not been studied before.

METHODS

A total of 145 patients diagnosed with OPSCC were enrolled. Immunohistochemical LMO7 expression and staining intensity were evaluated in the tumors and correlated with known clinical and pathological prognostic factors, such as HPV status and LRIG1, CD44, Ki67, and p53 expression.

RESULTS

Our results show that high LMO7 expression is associated with significantly longer overall survival (OS) (p = 0.044). LMO7 was a positive prognostic factor for OS in univariate analysis (HR 0.515, 95% CI: 0.267-0.994, p = 0.048) but not in multivariate analysis. The LMO7 expression correlated with LRIG1 expression (p = 0.048), consistent with previous findings. Interestingly, strong LRIG1 staining intensity was an independent negative prognostic factor in the HPV-driven group of tumors (HR 2.847, 95% Cl: 1.036-7.825, p = 0.043).

CONCLUSIONS

We show for the first time that high LMO7 expression is a positive prognostic factor in OPSCC, and we propose that LMO7 should be further explored as a biomarker. In contrast to previous reports, LRIG1 expression was shown to be an independent negative prognostic factor in HPV-driven OPSCC.

Prognostic significance of LRIG2 and LRIG3 proteins in urothelial bladder carcinoma

Bladder carcinoma is the second most frequent cancer in Egyptian males. Leucine-rich and immunoglobulin-like domains (LRIGs) are usually dysregulated in various human tumors. The aim of this study is to explore the immunohistochemical expression of LRIG2 and LRIG3 in urothelial bladder carcinoma (UBC) and their relationship to patients clinicopathological data including survival. The study cohort included 79 UBC cases (14 non muscle invasive (NMI) and 65 muscle invasive (MI)). We assessed the associations of LRIG2 and LRIG3 expression with clinicopathological data, as well as progression-free and overall survival. Most of studied cases (>50%) express LRIG2 and LRIG3. Statistically significant association was observed between positivity for LRIG3 and muscle invasion (P = 0.001), high grade (P = 0.03), and female gender (P = 0.02). Moreover, positive LRIG2 staining was associated with early stage (T2) (P = 0.03), lymphovascular invasion (P = 0.004), and tendency to non-muscle invasive stage (P = 0.07). Grouping of cases according to positivity/negativity of both markers showed that cases with dual positivity for both proteins are associated with muscle invasion (P = 0.001) and paradoxically with prolonged overall survival (P = 0.037). We conclude that although the association of LRIG3 with MI and high-grade tumors, its expression is related to better survival. LRIG3 has the dominant role even if it coexists with LRIG2. The role of LRIG2 remains to be further investigated.

The Prognostic Role of LRIG Proteins in Endometrial Cancer

Endometrial cancer (EC) is the most common gynecologic malignancy in Sweden and it has various prognostic factors. The LRIG family is a group of three integral surface proteins with a similar domain organization. The study aimed to explore LRIG family as prognostic factor proteins in EC. The initial study cohort included 100 women with EC who were treated at the Department of Women's and Children's Health, Karolinska University Hospital Solna, between 2007 and 2012. We assessed the associations between LRIG protein expression and type, grade, and stage of EC, as well as progression-free and overall survival. Immunohistochemistry results revealed that most women in the analytical sample had >50% LRIG1-, LRIG2- and LRIG3-positive cells. A statistically significant association was observed between having a high number of LRIG3-positive cells and superior overall survival (incidence rate ratio = 0.977; 95% confidence interval: 0.958-0.996, p = 0.019). Moreover, positive LRIG3 staining of the cell membrane was associated with reducing in the risk of death (hazard ratio = 0.23; 95% confidence interval: 0.09-0.57). Our results show that LRIG3 expression might be a prognostic factor in EC. The role of LRIG1 and LRIG2 expression remains to be further investigated.

LRIG3 Suppresses Angiogenesis by Regulating the PI3K/AKT/VEGFA Signaling Pathway in Glioma

High levels of microvessel density (MVD) indicate poor prognosis in patients with malignant glioma. Leucine-rich repeats and immunoglobulin-like domains (LRIG) 3, a potential tumor suppressor, plays an important role in tumor progression and may serve as a biomarker in many human cancers. However, its role and underlying mechanism of action in glioma angiogenesis remain unclear. In the present study, we used loss- and gain-of-function assays to show that LRIG3 significantly suppressed glioma-induced angiogenesis, both in vitro and in vivo. Mechanistically, LRIG3 inhibited activation of the PI3K/AKT signaling pathway, downregulating vascular endothelial growth factor A (VEGFA) in glioma cells, thereby inhibiting angiogenesis. Notably, LRIG3 had a significant negative correlation with VEGFA expression in glioma tissues. Taken together, our results suggest that LRIG3 is a novel regulator of glioma angiogenesis and may be a promising option for developing anti-angiogenic therapy.

The Prognostic and Therapeutic Potential of LRIG3 and Soluble LRIG3 in Glioblastoma

Glioblastoma is a highly lethal type of primary brain tumor that exhibits unrestricted growth and aggressive invasion capabilities, leading to a dismal prognosis despite a multitude of therapies. Multiple alterations in the expression level of genes and/or proteins have been identified in glioblastomas, including the activation of oncogenes and/or silencing of tumor-suppressor genes. Nevertheless, there are still no effective targeted therapies associated with these changes. In this study, we investigated the expression of human leucine-rich repeats and immunoglobulin-like domains protein 3 (LRIG3) in human glioma specimens through immunohistochemical analysis. The results showed that LRIG3 was weakly expressed in high-grade gliomas (WHO [World Health Organization] grades III and IV) compared with that in low-grade gliomas (WHO grade II). Survival analysis of these patients with glioma indicated that LRIG3 is an important prognostic marker for better survival. Moreover, we confirmed the existence of soluble ectodomain of LRIG3 (sLRIG3) in the cell culture supernatant, serum, and in tumor cystic fluid of patients with glioma. Molecular mechanistic investigation demonstrated that both LRIG3 and sLRIG3 inhibit the growth and invasion capabilities of GL15, U87, and PriGBM cells and tumor xenografts in nude mice through regulating the MET/phosphatidylinositol 3-kinase/Akt signaling pathway. Enzyme-linked immunosorbent assay confirmed the positive correlation between serum sLRIG3 protein levels and overall survival time in patients with high-grade gliomas. Taken together, our data for the first time demonstrate the existence of sLRIG3 and that both LRIG3 and sLRIG3 are potent tumor suppressors, which could be used as prognostic markers for better overall survival and therapeutic agents for glioblastoma.

LRIG1‑2 and LMO7 immunoreactivity in vulvar squamous cell carcinoma: Association with prognosis in relation to HPV‑DNA and p16INK4a status

The present study was conducted to investigate the possible prognostic value of molecular markers LRIG1‑2 and LIM domain 7 protein (LMO7) in vulvar squamous cell carcinoma (VSCC) and their possible correlation to human papilloma virus (HPV)‑ and p16INK4a‑status of the tumors. Patients diagnosed with VSCC at the University Hospital of Umeå, Sweden, during the years 1990‑2013 were selected. Tumor blocks were retrieved from tissue archives and clinical data were collected from the records of patients. HPV‑PCR analysis, HPV genotyping and immunohistochemistry were performed. In total, 112 patients were included. Forty percent of the tumors were HPV‑positive, 27% were p16INK4a‑positive and 23% were positive for both HPV and p16INK4a (considered HPV‑driven). HPV‑positivity and p16INK4a‑positivity were associated with prolonged disease‑free survival (DFS) in Kaplan‑Meier survival analysis. Leucine‑rich repeats and immunoglobulin‑like domains 1 (LRIG1) immunoreactivity was not significantly associated with survival. High leucine‑rich repeats and immunoglobulin‑like domains 2 (LRIG2) immunoreactivity was associated with a prolonged overall survival (OS) (P=0.001). By analyzing HPV‑negative cases only, it was determined that high LRIG2 immunoreactivity was associated with both favorable OS (P=0.008) and DFS (P=0.031). LRIG2 immunoreactivity was also an independent prognostic factor in multivariate analysis of OS (P=0.002, HR=0.41; 95% CI, 0.24‑0.71). High immunoreactivity with LMO7‑1250 antibody was associated with survival benefits in the whole cohort (OS; P=0.011) although DFS was only prolonged in HPV‑negative and not HPV‑driven tumors (P=0.038 and 0.042, respectively). The present study indicated that LRIG2 and LMO7 may be useful prognostic markers in VSCC, particularly for patients without HPV‑driven tumors or with advanced tumors at diagnosis. In contrast to earlier observations regarding other types of squamous cell carcinoma, LRIG1 was not a significant prognostic factor in VSCC.

LRIG1 acts as a critical regulator of melanoma cell invasion, migration, and vasculogenic mimicry upon hypoxia by regulating EGFR/ERK-triggered epithelial-mesenchymal transition

Intratumoral hypoxia is a well-known feature of solid cancers and constitutes a major contributor to cancer metastasis and poor outcomes including melanoma. Leucine-rich repeats and Ig-like domains 1 (LRIG1) participate in the aggressive progression of several tumors, where its expression is frequently decreased. In the present study, hypoxia exposure aggravated melanoma cell invasion, migration, vasculogenic mimicry (VM), and epithelial–mesenchymal transition (EMT). During this process, LRIG1 expression was also decreased. Importantly, overexpression of LRIG1 notably counteracted hypoxia-induced invasion, migration, and VM, which was further augmented after LRIG1 inhibition. Mechanism analysis corroborated that LRIG1 elevation muted hypoxia-induced EMT by suppressing E-cadherin expression and increasing N-cadherin expression. Conversely, cessation of LRIG1 further potentiated hypoxia-triggered EMT. Additionally, hypoxia stimulation activated the epidermal growth factor receptor (EGFR)/ERK pathway, which was dampened by LRIG1 up-regulation but further activated by LRIG1 inhibition. More important, blocking this pathway with its antagonist erlotinib abrogated LRIG1 suppression-induced EMT, and subsequently cell invasion, migration, and VM of melanoma cells under hypoxia. Together, these findings suggest that LRIG1 overexpression can antagonize hypoxia-evoked aggressive metastatic phenotype by suppressing cell invasion, migration, and VM via regulating EGFR/ERK-mediated EMT process. Therefore, these findings may provide a promising target for melanoma therapy.

Clinicopathological and prognostic significance of leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) in malignant tumors: A meta-analysis

Background: Accumulating studies have demonstrated that the expression of leucine-rich repeats and immunoglobulin-like domains protein1 (LRIG1) is associated with various types of tumors. However, the conclusions of previous studies are not completely consistent. Thus, we conducted this meta-analysis to further explore the authentic value of LRIG1 in cancer outcome and clinical significance.

Methods: We systematically searched electronic databases including PubMed, Web of Science, Embase, Chinese National Knowledge Infrastructure and Wanfang database. The hazard ratios (HRs), odds ratio (OR) and 95 % confidence intervals (CI) were calculated for effect measures.

Results: 16 qualified studies involving 2043 patients with cancer were enrolled. High LRIG1 expression was associated with a good prognosis in malignant tumors (HR: 0.49, 95% CI=0.39-0.59). Furthermore, positive expression rate of LRIG1 was distinctly lower in cancer tissues than that in normal tissues (OR: 0.09, 95% CI=0.05-0.17). Positive LRIG1 expression was definitely related with smaller tumor size (OR: 1.64, 95% CI=1.11-2.42), early tumor stage (OR: 3.67, 95% CI=1.87-7.21), well degree of differentiation (OR: 4.35, 95% CI=2.12-8.93) and negative recurrence (OR: 0.29, 95% CI=0.16-0.53).

Conclusions: LRIG1 expression was associated with a good prognosis in terms of overall survival (OS) and might act as a predictive factor for characteristics of cancer patients.

LRIG2 promotes the proliferation and cell cycle progression of glioblastoma cells in vitro and in vivo through enhancing PDGFRβ signaling

The leucine-rich repeats and immunoglobulin-like domains (LRIG) gene family, comprising LRIG1, 2 and 3, encodes integral membrane proteins. It has been well established that LRIG1 negatively regulates multiple growth factor signaling pathways and is considered to be a tumor suppressor; however, the biological functions of LRIG2 remain largely unexplored. It was previously demonstrated that LRIG2 positively regulates epidermal growth factor receptor (EGFR) signaling, the most common aberrant receptor tyrosine kinase (RTK) signaling in glioblastoma multiforme (GBM), which promotes GBM growth. In the present study, the effect of LRIG2 on the proliferation of GBM cells was further addressed, as well as the possible mechanisms underlying the regulatory effect of LRIG2 on platelet-derived growth factor receptor β (PDGFRβ) signaling, another common oncogenic RTK signaling pathway in GBM. First, the expression levels of endogenous LRIG2 and PDGFRβ were found to vary notably in human GBM, and the LRIG2 expression level was positively correlated with the expression level of PDGFRβ. Furthermore, to the best of our knowledge, this is the first study to demonstrate that LRIG2 promoted the PDGF-BB-induced proliferation of GBM cells in vitro and in vivo through regulating the PDGFRβ signaling-mediated cell cycle progression. Mechanistically, LRIG2 has the ability to physically interact with PDGFRβ, promoting the total expression and the activation of PDGFRβ, and enhancing its downstream signaling pathways of Akt and signal transducer and activator of transcription 3 and the effectors of key regulators of cell cycle progression, resulting in increased GBM cell proliferation. Collectively, these data indicated that LRIG2 may serve as a tumor promoter gene in gliomagenesis by positively regulating PDGFRβ signaling, another important oncogenic RTK signaling pathway, in addition to the previously reported EGFR signaling in GBM modulated by LRIG2, and validated LRIG2 as a promising therapeutic target for the treatment of GBM characterized by multiple aberrant RTK signaling.