Clinical Significance of Hu-Antigen Receptor (HuR) and Cyclooxygenase-2 (COX-2) Expression in Human Malignant and Benign Thyroid Lesions

High COX-2 immunostaining in papillary thyroid carcinoma is associated with adverse survival outcomes

BACKGROUND

Thyroid carcinoma is one of the most common malignancies worldwide. More than 70%-80% are papillary thyroid carcinoma (PTC). Many factors influence the PTC pathway of development such as genetic mutations, growth factors, and radiation. More biological understanding of the genetic and molecular pathways is needed in PTC to determine tumor behavior, and initial clinical assessment.

OBJECTIVES

Investigate the relation of COX-2 immunostaining in thyroid carcinoma with clinicopathological parameters to assess whether immunostaining results have prognostic significance.

DESIGN

Retrospective study SETTING: Pathology department, tertiary care center METHODS: Records of PTC were retrieved and tissue microarrays were constructed. Tissue sections were stained using anti-human COX-2 monoclonal antibody. Immunostaining results were recorded and analysed.

MAIN OUTCOME MEASURES

Relationship of COX-2 immunostaining in thyroid carcinoma with clinicopathological parameters.

SAMPLE SIZE

139 tissue samples from 139 patients RESULTS: High versus low COX-2 immunostaining showed no significant differences for most clinicopathological parameters. However, high COX-2 immunostaining showed borderline association with tumor multifocality (P=.05), lower overall (log-rank=8.739 and P=.003), and disease-free survival (log-rank=7.033, P=.008).

CONCLUSION

The study showed a positive association of high COX-2 immunostaining with lower survival outcomes in PTC. COX-2 immunostaining could be a potential prognostic factor for survival in PTC. Additional molecular and clinical investigations are needed for further understanding the molecular pathways of COX-2 in PTC and the feasibility of using inhibitors of COX-2 as adjuvant therapy along with current chemotherapy.

LIMITATIONS

Relatively low number of PTC variants, and no testing of other thyroid carcinomas.

CONFLICT OF INTEREST

None.

Divulging the Critical Role of HuR in Pancreatic Cancer as a Therapeutic Target and a Means to Overcome Chemoresistance

Simple Summary

With pancreatic cancer incidence constantly rising, constituting one of the most lethal type of cancers worldwide, the need for discovering novel therapeutic targets and approaches becomes of the utmost importance. Meanwhile, modern eating habits, hyperadiposity, mutational burden affecting core signaling pathways and the unique tumor microenvironment of pancreatic cancer tissues intermingle and form a disease that is lethal and hard to treat. The importance of HuR in pancreatic cancer has repeatedly been observed and represents a key molecule in pancreatic carcinogenesis and chemoresistance. Therefore, creating and obtaining new therapeutic skills against HuR protein could prove to be the answer to pancreatic cancer therapy.

Abstract

Pancreatic cancer is set to become the most lethal and common type of cancer worldwide. This is partly attributed to the mutational burden that affects core signaling pathways and the crosstalk of tumor cells with their surrounding microenvironment, but it is also due to modern eating habits. Hyperadiposity along with the constant rise in metabolic syndrome’s incidence contribute to a state of metaflammation that impacts immune cells and causes them to shift towards an immunosuppressive phenotype that, ultimately, allows tumor cells to evade immune control. Unfortunately, among the conventional therapeutic modalities and the novel therapeutic agents introduced, pancreatic cancer still holds one of the lowest response rates to therapy. Human antigen R (HuR), an RNA binding protein (RBP), has been repeatedly found to be implicated in pancreatic carcinogenesis and chemotherapy resistance through the posttranscriptional binding and regulation of mRNA target genes. Additionally, its overexpression has been linked to adverse clinical outcomes, in terms of tumor grade, stage, lymph node status and metastasis. These properties suggest the prospective role that HuR’s therapeutic targeting can play in facilitating pancreatic neoplasia and could provide the means to overcome chemoresistance.

HuR as Therapeutic Target in Cancer: What the Future Holds

ELAV-like protein 1, or HuR (human antigen R), is an RNA-binding protein encoded by the ELAVL1 gene in humans. One of its best functions is to stabilize mRNAs in order to regulate gene expression. HuR protein overexpression has undoubtedly been linked to an increased risk of tumor growth, progression, and metastasis, rendering it a potential therapeutic target candidate in cancer. Novel agents interfering with HuR expression have been tested, both in vitro and in vivo, with promising results. The aim of this paper is to review the existing literature regarding the potential agents that could actively act on and inhibit HuR expression. HuR molecule controls the expression of various proto-oncogenes, cytokines and growth factors, representing a major player in tumor progression, invasion, and metastasis and constituting an emerging target for cancer therapy. PubMed database was thoroughly searched, and all published articles providing scientific data on molecules that can exhibit antitumorigenic effects via HuR inhibition were included. According to these data, HuR inhibition should be a promising target in cancer therapeutics.

HuR Protein in Hepatocellular Carcinoma: Implications in Development, Prognosis and Treatment

Hu-antigen R (HuR) is a post-transcriptional regulator that belongs to the embryonic lethal abnormal vision Drosophila-like family (ELAV). HuR regulates the stability, translation, subcellular localization, and degradation of several target mRNAs, which are implicated in carcinogenesis and could affect therapeutic options. HuR protein is consistently highly expressed in hepatocellular carcinoma (HCC) compared to the adjacent normal liver tissue and is involved in the post-transcriptional regulation of various genes implicated in liver malignant transformation. Additionally, HuR protein seems to be a putative prognosticator in HCC, predicting worse survival. This review summarizes the recent evidence regarding the role of HuR in primary liver tumors, as presented in clinical studies, in vitro experiments and in vivo animal models. In conclusion, our review supports the consistent role of HuR protein in the development, prognosis, and treatment of HCC. Additional studies are expected to expand current information and exploit its putative employment as a future candidate for more personalized treatment in these tumors.

Prognostic Significance of COX-2 Overexpression in BRAF-Mutated Middle Eastern Papillary Thyroid Carcinoma

The cyclooxygenase-2 (COX-2)–prostaglandin E2 (PGE2) pathway has been implicated in carcinogenesis, with BRAF mutation shown to promote PGE2 synthesis. This study was conducted to evaluate COX-2 expression in a large cohort of Middle Eastern papillary thyroid carcinoma (PTC), and further evaluate the prognostic significance of COX-2 expression in strata of BRAF mutation status. BRAF mutation analysis was performed using Sanger sequencing, and COX-2 expression was evaluated immunohistochemically using tissue microarray (TMA). COX-2 overexpression, noted in 43.2% (567/1314) of cases, was significantly associated with poor prognostic markers such as extra-thyroidal extension, lymph-node metastasis, and higher tumor stage. COX-2 was also an independent predictor of poor disease-free survival (DFS). Most notably, the association of COX-2 expression with DFS differed by BRAF mutation status. COX-2 overexpression was associated with poor DFS in BRAF-mutant but not BRAF wild-type PTCs, with a multivariate-adjusted hazard ratio of 2.10 (95% CI = 1.52–2.92; p < 0.0001) for COX-2 overexpressed tumors in BRAF-mutant PTC. In conclusion, the current study shows that COX-2 plays a key role in prognosis of PTC patients, especially in BRAF-mutated tumors. Our data suggest the potential therapeutic role of COX-2 inhibition in patients with BRAF-mutated PTC.

The RNA Binding Protein HuR: A Promising Drug Target for Anticancer Therapy

The stability of mRNA is one of the key factors governing the regulation of eukaryotic gene expression and function. Human antigen R (HuR) is an RNA-binding protein that regulates the stability, translation, and nucleus-to-cytoplasm shuttling of its target mRNAs. While HuR is normally localized within the nucleus, it has been shown that HuR binds mRNAs in the nucleus and then escorts the mRNAs to the cytoplasm where HuR protects them from degradation. It contains several RNA recognition motifs, which specifically bind to adenylate and uridylate-rich regions within the 3'-untranslated region of the target mRNA to mediate its effect. Many of the HuR target mRNAs encode proteins important for cell growth, tumorigenesis, angiogenesis, tumor inflammation, invasion and metastasis. HuR overexpression is known to correlate well with high-grade malignancy and poor prognosis in many tumor types. Thus, HuR has emerged as an attractive drug target for cancer therapy. Novel small molecule HuR inhibitors have been identified by high throughput screening and new formulations for targeted delivery of HuR siRNA to tumor cells have been developed with promising anticancer activity. This review summarizes the significant role of HuR in cancer development, progression, and poor treatment response. We will discuss the potential and challenges of targeting HuR therapeutically.

Approach the Invasive Potential with Hurthle Cell Tumors of Thyroid

To observe the expression of P53, CyclinD1, Ki-67, Galectin-3, COX-2, Bcl-2 and approach their contribution on assessing the invasive potential for Hurthle cell tumors. Seventy-three cases of Hurthle cell tumor were collected for immunohistochemistry staining. The patients were followed up with 8 months to 5 years. Tumors were divided into four grades according to invasion and diameter:(1) extremely low risk (27 cases that less than 2 cm and without invasion), (2) low risk (18 cases that within 2-3.9 cm and without invasion), (3) moderate risk (21 cases that achieve 4 cm and without invasion), (4) high risk (7 cases that with invasion of capsule/vessel in spite of the diameter). Immunostaining presented that all 73 cases were positive with Galectin-3, COX-2 and Bcl-2. For each group, P53 positive were 29.6%, 55.6%, 90.5%, 100.0%; CyclinD1 stained with 7.4%,22.2%,52.4%,100.0% and Ki-67 were 0.0%,5.6%,9.5%,28.6%, respectively. The higher risk of tumor, the more cases that positive expressed P53 and CyclinD1. After following up within 49 patients, two of the recurring cases were positive with P53 and CyclinD1 and one of which was also highly expressed Ki-67. Detecting P53, CyclinD1 and Ki-67 might provide reference for invasive potential assessment with Hurthle cell tumors but not Galectin-3, COX-2 and Bcl-2.

Clinical Significance and Biological Role of HuR in Head and Neck Carcinomas

Background

Hu-antigen R (HuR) is a posttranscriptional regulator of several target mRNAs, implicated in carcinogenesis. This review aims to present the current evidence regarding the biological role and potential clinical significance of HuR in head and neck carcinomas.

Methods

The existing literature concerning HuR expression and function in head and neck carcinomas is critically presented and summarised.

Results

HuR is expressed in the majority of the examined samples, showing higher cytoplasmic levels in malignant or premalignant cases. Moreover, HuR modulates several genes implicated in biological processes important for malignant transformation, growth, and invasiveness. HuR seems to be an adverse prognosticator in patients with OSCCs, whereas a correlation with a more aggressive phenotype is reported in several types of carcinomas.

Conclusions

A consistent role of HuR in the carcinogenesis and progression of head and neck carcinomas is suggested; nevertheless, further studies are warranted to expand the present information.

Cyclooxygenase-2 (COX-2) gene polymorphism in patients with differentiated thyroid carcinomas in the Turkish population

Background/aim: The most common thyroid malignancies are papillary and follicular thyroid carcinomas. They account for approximately 85%-90% of all thyroid cancers. Recent studies have reported the relevance of cyclooxygenase-2 (COX-2) gene polymorphism in human carcinogenesis. The aim of this study was to investigate the relationship between thyroid carcinoma and COX-2 gene polymorphism in the Turkish population.Materials and methods: We included a total of 96 differentiated thyroid cancer patients (mean age: 46.9 ± 10.3 years; 14 males, 82 females) and 83 healthy control subjects (mean age: 46.0 ± 10.6 years; 39 males, 44 females). The frequency of -765G>C, -8473T>C, and 1195A>G gene polymorphisms in the COX-2 promoter region was investigated in thyroid cancer patients and the control group using the high-resolution melting method. Results: COX-2-765G>C and COX-2-1195A>G gene polymorphisms were similar between thyroid cancer patients and the control group. There was a statistically significant difference between COX-2-8473T>C gene polymorphism in the thyroid cancer group and the control group (P = 0.012).Conclusion: The single nucleotide gene polymorphism COX-2-8473T>C might contribute to genetic susceptibility to differentiated thyroid cancer in the Turkish population.

Detrimental ELAVL-1/HuR-dependent GSK3β mRNA stabilization impairs resolution in acute respiratory distress syndrome

A hallmark of acute respiratory distress syndrome (ARDS) is accumulation of protein-rich edema in the distal airspaces and its removal is critical for patient survival. Previous studies have shown a detrimental role of Glycogen Synthase Kinase (GSK) 3β during ARDS via inhibition of alveolar epithelial protein transport. We hypothesized that post-transcriptional regulation of GSK3β could play a functional role in ARDS resolution. To address this hypothesis, we performed an in silico analysis to identify regulatory genes whose expression correlation to GSK3β messenger RNA utilizing two lung cancer cell line array datasets. Among potential regulatory partners of GSK3β, these studies identified the RNA-binding protein ELAVL-1/HuR (Embryonic Lethal, Abnormal Vision, Drosophila-Like) as a central component in a likely GSK3β signaling network. ELAVL-1/HuR is a RNA-binding protein that selectively binds to AU-rich elements of mRNA and enhances its stability thereby increasing target gene expression. Subsequent studies with siRNA suppression of ELAVL-1/HuR demonstrated deceased GSK3β mRNA and protein expression and improved clearance of FITC-albumin in A549 cells. Conversely, stabilization of ELAVL-1/HuR with the proteasome inhibitor MG-132 resulted in induction of GSK3β at mRNA and protein level and attenuated FITC-albumin clearance. Utilizing ventilator-induced lung injury or intra-tracheal installation of hydrochloric acid to induce ARDS in mice, we observed increased mRNA and protein expression of ELAVL-1/HuR and GSK3β. Together, our findings indicate a previously unknown interaction between GSK3β and ELAV-1 during ARDS, and suggest the inhibition of the ELAV-1- GSK3β pathways as a novel ARDS treatment approach.