Decreased LRIG1 in fulvestrant-treated luminal breast cancer cells permits ErbB3 upregulation and increased growth

Preservation of 5-Hydroxymethylcytosine Levels in LRIG1 across Genomic DNA and Cell-Free DNA in Glioma Patients

Cell-free DNA (cfDNA) has recently emerged as a promising minimally invasive diagnostic biomarker for various cancers. In this study, our aim was to identify cfDNA biomarkers by investigating genes that displayed significant differences between glioma patients and their corresponding controls. To accomplish this, we utilized publicly available data from the Gene Expression Omnibus, focusing on 5-hydroxymethylcytosine (5hmC) profiles in both cfDNA and genomic DNA (gDNA) from glioma patients and healthy individuals. The intersection of gene lists derived from these comparative analyses unveiled LRIG1 and ZNF703 as the two genes with elevated 5hmC levels in both the cfDNA of glioma patients and gDNA of glioma tissue compared to their respective controls. The gene expression data revealed both genes were upregulated in glioma tissue compared to normal brain tissue. Integration of 5hmC data revealed a strong positive correlation in the glioma tissue group between 5hmC and the gene expression of the LRIG1 gene. Furthermore, exploration using the AmiCa web tool indicated that LRIG1 gene expression was elevated compared to 17 other cancers included in the database, emphasizing its potential as a distinctive biomarker across multiple cancer types.

Single-molecule array assay reveals the prognostic impact of plasma LRIG1 in ovarian carcinoma

BACKGROUND

Ovarian carcinoma is the eighth most common cause of cancer death in women worldwide. The disease is predominantly diagnosed at a late stage. This contributes to high recurrence rates, eventually leading to the development of treatment-resistant disease. Leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) is a transmembrane protein that functions as a tumor suppressor and regulator of growth factor signaling. LRIG1 levels have not been investigated in human plasma previously.

MATERIALS AND METHODS

A quantitative LRIG1-specific single molecule array assay was developed and validated. LRIG1 levels were quantified in plasma samples from 486 patients with suspicious ovarian masses.

RESULTS

Among women with ovarian carcinoma, LRIG1 levels were significantly elevated compared to women with benign or borderline type tumors. High LRIG1 plasma levels were associated with worse overall survival and shorter disease-free survival both in the group of all malignant cases and among the stage 3 cases only. LRIG1 was an independent prognostic factor in patients with stage 3 ovarian carcinoma.

CONCLUSION

LRIG1 plasma levels were elevated in patients with ovarian carcinoma, and high levels were associated with poor prognosis, suggesting that LRIG1 might be an etiologic factor and a potentially useful biomarker in ovarian carcinoma.

LRIG1 is a pleiotropic androgen receptor-regulated feedback tumor suppressor in prostate cancer

LRIG1 has been reported to be a tumor suppressor in gastrointestinal tract and epidermis. However, little is known about the expression, regulation and biological functions of LRIG1 in prostate cancer (PCa). We find that LRIG1 is overexpressed in PCa, but its expression correlates with better patient survival. Functional studies reveal strong tumor-suppressive functions of LRIG1 in both AR+ and AR- xenograft models, and transgenic expression of LRIG1 inhibits tumor development in Hi-Myc and TRAMP models. LRIG1 also inhibits castration-resistant PCa and exhibits therapeutic efficacy in pre-established tumors. We further show that 1) AR directly transactivates LRIG1 through binding to several AR-binding sites in LRIG1 locus, and 2) LRIG1 dampens ERBB expression in a cell type-dependent manner and inhibits ERBB2-driven tumor growth. Collectively, our study indicates that LRIG1 represents a pleiotropic AR-regulated feedback tumor suppressor that functions to restrict oncogenic signaling from AR, Myc, ERBBs, and, likely, other oncogenic drivers.

TTF-1/Nkx2.1 functional connection with mutated EGFR relies on LRIG1 and β-catenin pathways in lung cancer cells

In non-small lung cancer, the expression of the transcription factor TTF-1/Nkx2.1 correlates with the presence of EGFR mutations, therefore TTF-1/Nkx2.1 expression is used to optimize an EGFR testing strategy and to guide clinical treatment. We investigate the molecular mechanisms underlying the functional connection between EGFR and TTF-1/Nkx2.1 gene expression in lung adenocarcinoma. Using the H1975 cell line as a non-small cell lung cancer model system and short hairpin RNA, we have selected clones with TTF-1/Nkx2.1 silenced expression. We have found that Leucine-rich immunoglobulin repeats-1 (LRIG1) gene is a direct target of TTF-1/Nkx2.1 and the transcription factor binding to the LRIG1 genomic sequence inhibits its gene expression. In TTF-1/Nkx2.1 depleted clones, we have found high levels of LRIG1 and decreased presence of EGFR protein. Furthermore, in TTF-1/Nkx2.1 depleted clones we detected a reduced β-catenin level and we provide experimental evidence indicating that TTF-1/Nkx2.1 gene expression is regulated by β-catenin. Published studies indicate that LRIG1 triggers EGFR degradation and that mutated EGFR induces β-catenin activity. Hence, with the present study we show that mutated EGFR, enhancing β-catenin, stimulates TTF-1/Nkx2.1 gene expression and, at the same time, TTF-1/Nkx2.1, down-regulating LRIG1, sustains EGFR pathway. Therefore, LRIG1 and β-catenin mediate the functional connection between TTF-1/Nkx2.1 and mutated EGFR.

Downregulation of leucine-rich repeats and immunoglobulin-like domains 1 by microRNA-20a modulates gastric cancer multidrug resistance

Multidrug resistance (MDR) significantly restricts the clinical efficacy of gastric cancer (GC) chemotherapy, and it is critical to search novel targets to predict and overcome MDR. Leucine‐rich repeats and immunoglobulin‐like domains 1 (LRIG1) has been proved to be correlated with drug resistance in several cancers. The present study revealed that LRIG1 was overexpressed in chemosensitive GC tissues and decreased expression of LRIG1 predicted poor survival in GC patients. We observed that upregulation of LRIG1 enhanced chemosensitivity in GC cells. Interestingly, miR‐20a, which was overexpressed in GC MDR cell lines and tissues, was identified to regulate LRIG1 expression by directly targeting its 3′ untranslated region. We also found that inhibition of miR‐20a suppressed GC MDR, and upregulation showed opposite effects. Moreover, we demonstrated that the miR‐20a/LRIG1 axis regulated GC cell MDR through epidermal growth factor receptor (EGFR)‐mediated PI3K/AKT and MAPK/ERK signaling pathways. Finally, LRIG1 expression in human GC tissues is inversely correlated with miR‐20a and EGFR. Taken together, the newly identified miR‐20a/LRIG1/EGFR link provides insight into the MDR process of GC, and targeting this axis represents a novel potential therapeutic strategy to block GC chemoresistance.

Evaluation of Protein Levels of the Receptor Tyrosine Kinase ErbB3 in Serum

The epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases (RTK) consists of four members: EGFR1/ErbB1/HER1, ErbB2/HER2, ErbB3/HER3, and HER4/ErbB4. Signaling through these receptors regulates many key cellular activities, such as cell division, migration, adhesion, differentiation, and apoptosis. The ErbB family has been shown to be overexpressed in different types of cancers and is a target of several inhibitors already in clinical trials. ErbB3 lacks a functional tyrosine kinase domain and therefore has not been as extensively studied as the other members of this family, but its importance in activating downstream pathways, such as the PI3K/Akt pathway, makes this RTK a worthy investigation target, especially in urothelial carcinoma where the PI3K/Akt pathway is vital for progression. In recent times, ErbB3 overexpression has been linked to drug resistance and progression of various diseases, especially cancer. ErbB3 levels in the serum were shown in many cases to be reflective of its role in disease progression, and therefore detection of serum ErbB3 levels during treatment may be of importance.Here we describe two methods for detecting ErbB3 protein in serum from patients who have undergone a clinical trial, utilizing two well-established methods in molecular biology-western blotting and ELISA, focusing on sample preparation and troubleshooting.

Associations of high altitude polycythemia with polymorphisms in EPAS1, ITGA6 and ERBB4 in Chinese Han and Tibetan populations

High altitude polycythemia (HAPC) is a common chronic disease at high altitude, which is characterized by excessive erythrocytosis (females, hemoglobin ≥ 190 g/L; males, hemoglobin ≥ 210 g/L). It is the most common disease in chronic mountain sickness casued primarily by persistent arterial hypoxia and ventilatory impairment. However, the disease is still unmanageable and related molecular mechanisms remain largely unclear. This study aims to explore the genetic basis of HAPC in the Chinese Han and Tibetan populations. Subjects were screened for HAPC using the latest approved diagnostic criteria. To explore the hereditary basis of HAPC and investigate the association between three genes (EPAS1, ITGA6, ERBB4) and HAPC in Chinese Han and Tibetan populations. We enrolled 100 patients (70 Han, 30 Tibetan) with HAPC and 100 healthy control subjects (30 Han, 70 Tibetan). Subjects were screened for HAPC using the latest approved diagnostic criteria combined with excessive erythrocytosis and clinical symptoms. Analysis of variance was used to evaluate the impact of polymorphism on HAPC based on genetic variation. The Chi-squared test and analyses of genetic models, rs75591953 and rs75984373 in EPAS1, rs6744873 in ITGA6, rs17335043 in ERBB4 showed associations with reduced HAPC susceptibility in Han populations. Additionally, in Tibetan populations, rs3749148 in ITGA6, rs934607 and rs141267844 in ERBB4 showed a reduced risk of HAPC, whereas rs6710946 in ERBB4 increased the risk of HAPC. Our study suggest that the polymorphisms in the EPAS1, ITGA6 and ERBB4 correlate with susceptibility to HAPC.

Harnessing LRIG1-mediated inhibition of receptor tyrosine kinases for cancer therapy

Leucine-rich repeats and immunoglobulin-like domains containing protein 1 (LRIG1) is an endogenous feedback regulator of receptor tyrosine kinases (RTKs) and was recently shown to inhibit growth of different types of malignancies. Additionally, this multifaceted RTK inhibitor was reported to be a tumor suppressor, a stem cell regulator, and a modulator of different cellular phenotypes. This mini-review provides a concise and up-to-date summary about the known functions of LRIG1 and its related family members, with a special emphasis on underlying molecular mechanisms and the opportunities for harnessing its therapeutic potential against cancer.