High Expression of NLRC5 Is Associated with Prognosis of Gastric Cancer

NLRC5 exerts anti-endometriosis effects through inhibiting ERβ-mediated inflammatory response

BACKGROUND

Endometriosis is well known as a chronic inflammatory disease. The development of endometriosis is heavily influenced by the estrogen receptor β (ERβ), while NOD-like receptors (NLRs) family CARD domain-containing 5 (NLRC5) exhibits anti-inflammatory properties during endometriosis. However, whether NLRC5-mediated anti-inflammation is involved in the ERβ-mediated endometriosis is still uncertain. This study aimed to assess that relation.

METHODS

Nine cases of eutopic endometrial tissue and ten cases of ectopic endometrial tissue were collected from patients with endometriosis, and endometrial samples from ten healthy fertile women were analyzed, and the expression levels of ERβ were quantified using immunohistochemistry (IHC). Subsequently, we constructed mouse model of endometriosis by intraperitoneal injection. We detected the expression of ERβ, NLRC5, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-10 and measured the volume of ectopic lesions in mice with endometriosis. In vitro, human endometrial stromal cells (hESCs) were transfected respectively with ERβ-overexpressing and NLRC5-overexpressing plasmids. We then assessed the expression of ERβ and NLRC5 using quantitative real-time PCR (qRT-PCR) and western blot analysis. Furthermore, we measured the concentrations of TNF-α, IL-6, and IL-10 in the cell culture supernatant through enzyme-linked immunosorbent assay (ELISA). Additionally, we evaluated the migration and invasion ability of hESCs using transwell and wound healing assays.

RESULTS

Inhibition of NLRC5 expression promotes the development of ectopic lesions in mice with endometriosis, upregulates the expression of pro-inflammatory factors TNF-α and IL-6, and downregulates the expression of anti-inflammatory factor IL-10. The high expression of NLRC5 in endometriosis depended on the ERβ overexpression. And ERβ promoted the migration of hESCs partially depend on inflammatory microenvironment. Lastly, NLRC5 overexpression inhibited ERβ-mediated development and inflammatory response of endometriosis.

CONCLUSIONS

Our results suggest that the innate immune molecule NLRC5-mediated anti-inflammation participates in ERβ-mediated endometriosis development, and partly clarifies the pathological mechanism of endometriosis, expanding our knowledge of the specific molecules related to the inflammatory response involved in endometriosis and potentially providing a new therapeutic target for endometriosis.

NLRC5 promotes endometrial carcinoma progression by regulating NF-κB pathway-mediated mismatch repair gene deficiency

The innate immune molecule NLR family CARD domain-containing 5 (NLRC5) plays a significant role in endometrial carcinoma (EC) immunosurveillance. However, NLRC5 also plays a protumor role in EC cells. Mismatch repair gene deficiency (dMMR) can enable tumors to grow faster and also can exhibit high sensitivity to immune checkpoint inhibitors. In this study, we attempted to determine whether NLRC5-mediated protumor role in EC is via the regulation of dMMR. Our findings revealed that NLRC5 promoted the proliferation, migration, and invasion abilities of EC cells and induced the dMMR status of EC in vivo and in vitro. Furthermore, the mechanism underlying NLRC5 regulated dMMR was also verified. We first found NLRC5 could suppress nuclear factor-kappaB (NF-κB) pathway in EC cells. Then we validated that the positive effect of NLRC5 in dMMR was restricted when NF-κB was activated by lipopolysaccharides in NLRC5-overexpression EC cell lines. In conclusion, our present study confirmed the novel NLRC5/NF-κB/MMR regulatory mechanism of the protumor effect of NLRC5 on EC cells, thereby suggesting that the NLRC5-mediated protumor in EC was depend on the function of MMR.

Relationship between NLRC5 gene polymorphisms and gastric cancer susceptibility

BACKGROUND

The NF-κB signaling pathway exerts a synergistic effect on gastric carcinogenesis. NLRC5 is an upstream regulator of the NF-κB signaling pathway, which is closely related to gastric carcinogenesis. Since NLRC5 expression is different among gastric cancer patients, we speculated that it might be related to NLRC5 gene polymorphisms. We explored the associations between NLRC5 gene polymorphism and gastric carcinogenesis through gene sequencing.

AIM

To investigate the associations of the NLRC5 rs56315364 and rs289726 gene polymorphisms with gastric cancer susceptibility and prognosis.

METHODS

A total of 75 gastric cancer patients and 59 healthy volunteers (age- and sex-matched) were enrolled in the study from September 2014 to October 2016. The NLRC5 rs56315364 and rs289726 genotypes were determined by first-generation sequencing of PCR products. Sequencing products were analyzed using MegAlign and Chromas 2.4.3 software. Differences in NLRC5 gene polymorphisms between patients with gastric cancer and healthy volunteers were identified to investigate the relationship between NLRC5 gene polymorphisms and the prognosis of gastric cancer.

RESULTS

The NLRC5 rs56315364 CC genotype increased the risk of gastric cancer [odds ratio (OR) = 7.06, 95% confidence interval (CI): 2.81-17.72], as did the rs289726 TC and CC genotypes (OR = 11.04, 95%CI: 4.29-28.43; OR = 4.77, 95%CI: 1.57-14.48, respectively). There was no significant difference in the genotype frequency of NLRC5 rs56315364 and rs289726 between the Helicobacter pylori (H. pylori)-negative group and the H. pylori-positive group (P > 0.05). Survival analysis showed that the NLRC5 rs289726 genotype was correlated with the prognosis of gastric cancer (P < 0.05), and the NLRC5 rs289726 CC genotype was associated with the worst prognosis. Multivariate Cox regression analysis showed that age and tumor-node-metastasis (TNM) stage were correlated with the prognosis of gastric cancer patients (P < 0.05)

CONCLUSION

The NLRC5 rs56315364 CC and rs289726 TC genotypes significantly increase the risk of gastric cancer. Older age and higher TNM stage are associated with the worse prognosis of patients with gastric cancer. The prognosis of gastric cancer patients with NLRC5 rs289726 CC genotype is the worst.

Inhibition of NLRC5 attenuates the malignant growth and enhances the sensitivity of gastric cancer cells to 5‑FU chemotherapy by blocking the carcinogenic effect of YY1

Gastric cancer (GC) is one of the commonest malignant tumors of the digestive system, characterized by high morbidity and mortality rates. It has been reported that NOD like receptor (NLR) family, CARD domain containing 5 (NLRC5) serves an important role in the occurrence and development of GC. Therefore, the current study aimed to investigate the role of NLRC5 in GC. The mRNA and protein expression levels of NLRC5 in GC cell lines were determined by reverse transcription-quantitative PCR and western blot analysis, respectively. Additionally, following NLRC5 knockdown, cell proliferation, invasion and migration were evaluated using Cell Counting Kit 8, colony formation, wound healing and Transwell assays, and western blot analysis. The NLRC and Yin Yang 1 (YY1) expression in the AGS cells with 5-FU resistance were detected by western blotting. The sensitivity of GC cells to 5-fluorouracil (5-FU) was detected by flow cytometry and western blot analysis. Additionally, the binding capacity of YY1 on NLRC5 promoter was predicted using JASPAR database and it was further verified by chromatin immunoprecipitation and luciferase reporter assays. Finally, to elucidate the mechanism underlying the effect of NLRC5 on GC, YY1 was overexpressed and NLRC5 was silenced in GC cell lines. The results showed that NLRC5 was abnormally upregulated in GC cells. In addition, NLRC5 knockdown significantly attenuated the proliferation, invasion and migration abilities of GC cells, while it enhanced the sensitivity of GC cells to 5-FU. The above effects were regulated by the YY1 transcription factor. Overall, the results of the present study indicated that NLRC5 silencing could reduce the malignant growth and enhance the sensitivity of GC cells to 5-FU chemotherapy via inhibiting the carcinogenic effect of YY1.

NLR family CARD domain containing 5 promotes hypoxia-induced cancer progress and carboplatin resistance by activating PI3K/AKT via carcinoembryonic antigen related cell adhesion molecule 1 in non-small cell lung cancer

It is well known that non-small cell lung cancer (NSCLC) is a malignant tumor with high incidence in the world. We aimed to clarify a possible target and identify its precise molecular biological mechanism in NSCLC. NLR family CARD domain containing 5 (NLRC5) is widely expressed in tissues and exerts a vital role in anti-tumor immunity. We determined NLRC5 expression by RT-qPCR and western blot assay. The role of NLRC5 in the development of NSCLC was assessed by a loss-of-function assay. CCK-8, Annexin-V-FITC/PI Apoptosis Detection Kit, Transwell, and wound healing assays were used to determine the cell functions. Drug resistance-related proteins were analyzed by western blot assay. Furthermore, the modulation of NLRC5 on carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) expression and subsequent PI3K/AKT signaling was assessed. In this study, a hyper-expression of NLRC5 was found in NSCLC tissues and cell lines. Knockdown of NLRC5 suppressed cell viability, invasion, and migration, and furthermore promoted cell apoptosis in NSCLC cells. Moreover, under normoxia or hypoxia treatment, the upregulation of NLRC5 was related to carboplatin resistance. NLRC5 silencing increased carboplatin-resistant cell chemosensitivity, as evidenced by the increase in the cell inhibition rate and decrease in drug resistance-related protein expression. Mechanistically, NLRC5 knockdown inhibited the expression of CEACAM1 and subsequently blocked the PI3K/AKT signaling pathway. In conclusion, NLRC5 promotes the malignant biological behaviors of NSCLC cells by activating the PI3K/AKT signaling pathway via the regulation of CEACAM1 expression under normoxia and hypoxia.

Clinical and Molecular Correlates of NLRC5 Expression in Patients With Melanoma

NLRC5 is an important regulator in antigen presentation and inflammation, and its dysregulation promotes tumor progression. In melanoma, the impact of NLRC5 expression on molecular phenotype, clinical characteristics, and tumor features is largely unknown. In the present study, public datasets from the Cancer Cell Line Encyclopedia (CCLE), Gene Expression Omnibus (GEO), The Cancer Genome Atlas (TCGA), and cBioPortal were used to address these issues. We identify that NLRC5 is expressed in both immune cells and melanoma cells in melanoma samples and its expression is regulated by SPI1 and DNA methylation. NLRC5 expression is closely associated with Breslow thickness, Clark level, recurrence, pathologic T stage, and ulceration status in melanoma. Truncating/splice mutations rather than missense mutations in NLRC5 could compromise the expression of downstream genes. Low expression of NLRC5 is associated with poor prognosis, low activity of immune-related signatures, low infiltrating level of immune cells, and low cytotoxic score in melanoma. Additionally, NLRC5 expression correlates with immunotherapy efficacy in melanoma. In summary, these findings suggest that NLRC5 acts as a tumor suppressor in melanoma via modulating the tumor immune microenvironment. Targeting the NLRC5 related pathway might improve efficacy of immunotherapy for melanoma patients.

miR-4319 Suppresses the Growth of Esophageal Squamous Cell Carcinoma Via Targeting NLRC5

BACKGROUND

The functions of microRNAs (miRNAs) in cancer progression have been recognized in recent years. However, the role of miR-4319 in esophageal squamous cell carcinoma (ESCC) remains unclear.

OBJECTIVE

We aimed to investigate the biological roles of miR-4319 in ESCC progression and the associated mechanisms.

METHODS

Real-time PCR was performed to examine the levels of miR-4319 in ESCC cell lines. The effects of miR-4319 and NOD-like receptor (NLR) family, caspase activation and recruitment domain (CARD) domain containing 5 (NLRC5) on cell proliferation and cell cycle progression were evaluated using MTT assay, colony formation and flow cytometry assays. Bioinformatics techniques and luciferase reporter assay were applied to validate NLRC5 as a miR-4319 target.

RESULTS

The miR-4319 expression was lower in ESCC cells than in the normal cell line. The expression of miR-4319 repressed cell growth and induced cell cycle arrest. NLRC5 was validated as a direct downstream target of miR-4319. Overexpression of NLRC5 potentiated the effects of miR-4319 on cell growth and cell cycle distribution.

CONCLUSION

Our results demonstrated that miR-4319 might function as a tumor suppressor by targeting NLRC5 in ESCC.

The MHC Class-I Transactivator NLRC5: Implications to Cancer Immunology and Potential Applications to Cancer Immunotherapy

The immune system constantly monitors the emergence of cancerous cells and eliminates them. CD8⁺ cytotoxic T lymphocytes (CTLs), which kill tumor cells and provide antitumor immunity, select their targets by recognizing tumor antigenic peptides presented by MHC class-I (MHC-I) molecules. Cancer cells circumvent immune surveillance using diverse strategies. A key mechanism of cancer immune evasion is downregulation of MHC-I and key proteins of the antigen processing and presentation machinery (APM). Even though impaired MHC-I expression in cancers is well-known, reversing the MHC-I defects remains the least advanced area of tumor immunology. The discoveries that NLRC5 is the key transcriptional activator of MHC-I and APM genes, and genetic lesions and epigenetic modifications of NLRC5 are the most common cause of MHC-I defects in cancers, have raised the hopes for restoring MHC-I expression. Here, we provide an overview of cancer immunity mediated by CD8⁺ T cells and the functions of NLRC5 in MHC-I antigen presentation pathways. We describe the impressive advances made in understanding the regulation of NLRC5 expression, the data supporting the antitumor functions of NLRC5 and a few reports that argue for a pro-tumorigenic role. Finally, we explore the possible avenues of exploiting NLRC5 for cancer immunotherapy.

MHC class I transactivator NLRC5 in host immunity, cancer and beyond

The presentation of antigenic peptides by major histocompatibility complex (MHC) class I and class II molecules is crucial for activation of the adaptive immune system. The nucleotide-binding domain and leucine-rich repeat receptor family members CIITA and NLRC5 function as the major transcriptional activators of MHC class II and class I gene expression, respectively. Since the identification of NLRC5 as the master regulator of MHC class I and class-I-related genes, there have been major advances in understanding the function of NLRC5 in infectious diseases and cancer. Here, we discuss the biological significance and mechanism of NLRC5-dependent MHC class I expression.

The lncRNA XIST promotes the progression of breast cancer by sponging miR-125b-5p to modulate NLRC5

X-inactivation-specific transcript (XIST) is a long noncoding RNA (lncRNA) that functions as an indicator of various human tumors, including those of breast cancer. This study was conducted to characterize a novel regulatory network involving XIST in breast cancer cells. The mRNAs of XIST, miR-125b-5p, and NOD-like receptor family CARD domain containing 5 (NLRC5) in breast cancer cells and tissues were analyzed using quantitative real-time polymerase chain reaction. Cell proliferation, apoptosis, migration, and invasion were separately detected via cell counting kit-8, flow cytometry, and Transwell assays. The relationships between XIST, miR-125b-5p, and NLRC5 were predicted and then confirmed using the dual-luciferase reporter assay. NLRC5 protein expression was quantitated using western blot assays. XIST was found to be overexpressed in breast cancer tissues and cells, which was accompanied by miR-125b-5p downregulation and NLRC5 upregulation. XIST knockdown significantly repressed cell proliferation, anti-apoptosis, migration, and invasion activities in breast cancer cells, and the loss of miR-125b-5p had a similar effect. XIST was shown to sponge miR-125b-5p, which in turn targeted NLRC5. NLRC5, a breast cancer promotor, is negatively regulated by miR-125b-5p. Moreover, the downregulation of NLRC5 induced by the loss of XIST was significantly reversed by miR-125b-5p knockdown. In conclusion, the lncRNA XIST promotes the malignancy of breast cancer cells partly by competitively binding to miR-125b-5p, which then led to increased NLRC5 expression. Our study suggests that targeting XIST may be a possible treatment for breast cancer.

NLRC5: new cancer buster?

Recent decades, there is significant progress in understanding the mechanisms of tumor progression and immune evasion. The newly discovered protein NLRC5 is demonstrated to participate in regulating cancer immune escape through enhancing MHC class I genes expression in certain tumors. Nevertheless, increasing evidence has revealed that NLRC5 is up-regulated in some other tumors and promote tumor development and progression. The purpose of this review is to describe the role of NLRC5 in tumors and discuss whether NLRC5 can be a potential target in cancer treatment.

Clinical Significance of Lysophosphatidic Acid Receptor-2 (LPA2) and Krüppel-Like Factor 5 (KLF5) Protein Expression Detected by Tissue Microarray in Gastric Adenocarcinoma

Background

The aim of this study was to evaluate lysophosphatidic acid receptor-2 (LPA2) and Krüppel-like factor 5 (KLF5) protein expression in gastric adenocarcinoma and their correlation with patient clinicopathological characteristics and prognosis.

Material/Methods

Fifty-one gastric adenocarcinoma tissue samples, 21 gastric intraepithelial neoplasia (GIN) samples, and 13 normal gastric tissue samples were collected to test for LPA2 and KLF5 expression by tissue microarray and immunohistochemistry assay. LPA2 and KLF5 positive expression rate between gastric adenocarcinoma, GIN, and normal gastric tissue were compared. The relationship between LPA2 expression, KLF5 expression, and patients’ clinicopathological characteristics and prognosis were evaluated.

Results

The positive expression rate of LPA2 and KLF5 were statistical different in gastric adenocarcinoma, GIN, and normal gastric tissue (P<0.05). LPA2 positive expression was associated with tumor invasion depth, Lauren type, vascular invasion, local lymph node metastasis, and clinical stage (P<0.05). There was no correlation between LPA2 expression (hazard ratio [HR]=1.84, 95% confidence interval [CI]: 0.89–3.80, P>0.05), KLF5 expression (HR=1.13, 95% CI: 0.53–2.36, P>0.05), and gastric cancer patients’ overall survival.

Conclusions

LPA2 and KLF5 protein expressions were differently expressed in gastric adenocarcinoma, GIN, and normal gastric tissue, and differences were correlated with patients’ clinical characteristic. However, LPA2 and KLF5 expressions were not correlated with the patients’ prognosis.

NOD-like receptors: major players (and targets) in the interface between innate immunity and cancer

Innate immunity comprises several inflammation-related modulatory pathways which receive signals from an array of membrane-bound and cytoplasmic pattern recognition receptors (PRRs). The NLRs (NACHT (NAIP (neuronal apoptosis inhibitor protein), C2TA (MHC class 2 transcription activator), HET-E (incompatibility locus protein from Podospora anserina) and TP1 (telomerase-associated protein) and Leucine-Rich Repeat (LRR) domain containing proteins) relate to a large family of cytosolic innate receptors, involved in detection of intracellular pathogens and endogenous byproducts of tissue injury. These receptors may recognize pathogen-associated molecular patterns (PAMPs) and/or danger-associated molecular patterns (DAMPs), activating host responses against pathogen infection and cellular stress. NLR-driven downstream signals trigger a number of signaling circuitries, which may either initiate the formation of inflammasomes and/or activate nuclear factor κB (NF-κB), stress kinases, interferon response factors (IRFs), inflammatory caspases and autophagy. Disruption of those signals may lead to a number of pro-inflammatory conditions, eventually promoting the onset of human malignancies. In this review, we describe the structures and functions of the most well-defined NLR proteins and highlight their association and biological impact on a diverse number of cancers.