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

Simple Summary

Over the past few years, there have been many studies investigating the LRIG (leucine-rich repeats and immunoglobulin-like domains) family of transmembrane proteins, focusing mainly on their role in cancer progression. However, the prognostic role of the proteins in endometrial cancer was not studied, even though it is the most common gynecologic cancer in developed countries. Therefore, our research group aimed to fill this knowledge gap. Here, our study analyzed endometrial cancer tissue using immunohistochemistry. As a result, we found that one of the LRIG proteins—LRIG3—might influence endometrial cancer survival rates. However, the role of the LRIG1 and LRIG2 proteins in the group remains to be clarified. In conclusion, our study expands upon knowledge on the prognostic role of LRIG family in gynecological malignancies.

Abstract

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.

LRIG3 represses cell motility by inhibiting slug via inactivating ERK signaling in human colorectal cancer

Metastasis is responsible for 90% of colorectal cancer (CRC)-related deaths. In the present study, we identified a novel key regulator of CRC metastasis, leucine-rich repeats and immunoglobulin-like domains protein 3 (LRIG3), which was significantly decreased in CRC tissues and cell lines. Downregulation of LRIG3 was attributed to copy number loss and promoter hypermethylation. Low LRIG3 expression was positively correlated with metastatic clinical features and shorter survival time. Functional experiments showed that knockout of LRIG3 markedly enhanced CRC cell migration and invasion ability, whereas reintroduction of LRIG3 exerted the opposite effects. Regarding the mechanism, LRIG3 could facilitate the binding of DUSP6 to ERK1/2, resulting in the dephosphorylation of ERK1/2 and subsequently downregulation of slug, an epithelial-to-mesenchymal transition trigger, thereby constraining CRC cell motility. Importantly, LRIG3 expression was strongly negatively correlated with slug or p-ERK1/2 expression in CRC tissues. Collectively, our data suggest that LRIG3 is a novel suppressor of CRC metastasis, reactivation of LRIG3 may be a promising therapeutic approach for metastatic CRC patients.

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.

Upregulation of microRNA-196a improves cognitive impairment and alleviates neuronal damage in hippocampus tissues of Alzheimer's disease through downregulating LRIG3 expression

PURPOSE

This study is launched to uncover the inner function of microRNA-196a (miR-196a) on cognitive dysfunction and neuronal damage in Alzheimer's disease (AD) rats through regulating the PI3K/Akt signaling pathway.

METHODS

The establishment of AD rat model was performed by a microinjection of Aβ_25-35 . miR-196a and LRIG3 expression was detected, and the putative binding site between them was also determined. The spatial learning and memory capability, the hippocampal neurons ultrastructure as well as the survival, and apoptosis of hippocampal neurons of rats were observed. The expression of apoptosis-associated protein, oxidative stress index, and inflammatory factors as well as the PI3K/Akt pathway-related factors was determined.

RESULTS

Initially, decreased miR-196a and increased LRIG3 were exhibited in hippocampus tissues of AD rats. In addition, restored miR-196a and deleted LRIG3 ameliorated spatial learning and memory capability, suppressed the pathological injury, induced the survival, and suppressed the apoptosis of hippocampal neurons, as well as inhibited oxidative stress injury together with inflammatory injury in AD rats. Furthermore, upregulation of miR-196a activated the PI3/Akt pathway in AD rats.

CONCLUSION

This current study suggests that upregulation of miR-196a and downregulation of LRIG3 improve cognitive impairment and alleviate neuronal damage in hippocampus tissues in AD rats via the modulation of the PI3K/Akt pathway.

LMO7 and LIMCH1 interact with LRIG proteins in lung cancer, with prognostic implications for early-stage disease

OBJECTIVES

The human leucine-rich repeats and immunoglobulin-like domains (LRIG) protein family comprises the integral membrane proteins LRIG1, LRIG2 and LRIG3. LRIG1 is frequently down-regulated in human cancer, and high levels of LRIG1 in tumor tissue are associated with favorable clinical outcomes in several tumor types including non-small cell lung cancer (NSCLC). Mechanistically, LRIG1 negatively regulates receptor tyrosine kinases and functions as a tumor suppressor. However, the details of the molecular mechanisms involved are poorly understood, and even less is known about the functions of LRIG2 and LRIG3. The aim of this study was to further elucidate the functions and molecular interactions of the LRIG proteins.

MATERIALS AND METHODS

A yeast two-hybrid screen was performed using a cytosolic LRIG3 peptide as bait. In transfected human cells, co-immunoprecipitation and co-localization experiments were performed. Proximity ligation assay was performed to investigate interactions between endogenously expressed proteins. Expression levels of LMO7 and LIMCH1 in normal and malignant lung tissue were investigated using qRT-PCR and through in silico analyses of public data sets. Finally, a clinical cohort comprising 355 surgically treated NSCLC cases was immunostained for LMO7.

RESULTS

In the yeast two-hybrid screen, the two paralogous proteins LMO7 and LIMCH1 were identified as interaction partners to LRIG3. LMO7 and LIMCH1 co-localized and co-immunoprecipitated with both LRIG1 and LRIG3. Endogenously expressed LMO7 was in close proximity of both LRIG1 and LRIG3. LMO7 and LIMCH1 were highly expressed in normal lung tissue and down-regulated in malignant lung tissue. LMO7 immunoreactivity was shown to be a negative prognostic factor in LRIG1 positive tumors, predicting poor patient survival.

CONCLUSION

These findings suggest that LMO7 and LIMCH1 physically interact with LRIG proteins and that expression of LMO7 is of clinical importance in NSCLC.

The LRIG family: enigmatic regulators of growth factor receptor signaling

The leucine-rich repeats and immunoglobulin-like domains (LRIG) family of transmembrane proteins contains three vertebrate members (LRIG1, LRIG2 and LRIG3) and one member each in flies (Lambik) and worms (Sma-10). LRIGs have stepped into the spotlight as essential regulators of growth factor receptors, including receptor tyrosine and serine/threonine kinases. LRIGs have been found to both negatively (LRIG1 and LRIG3) and positively (Sma-10 and LRIG3) regulate growth factor receptor expression and signaling, although the precise molecular mechanisms by which LRIGs function are not yet understood. The most is known about LRIG1, which was recently demonstrated to be a tumor suppressor. Indeed, in vivo experiments reinforce the essential link between LRIG1 and repression of its targets for tissue homeostasis. LRIG1 has also been identified as a stem cell marker and regulator of stem cell quiescence in a variety of tissues, discussed within. Comparably, less is known about LRIG2 and LRIG3, although studies to date suggest that their functions are largely distinct from that of LRIG1 and that they likely do not serve as growth/tumor suppressors. Finally, the translational applications of expressing soluble forms of LRIG1 in LRIG1-deficient tumors are being explored and hold tremendous promise.