Matrix metalloproteinase 12 is induced by heterogeneous nuclear ribonucleoprotein K and promotes migration and invasion in nasopharyngeal carcinoma

HnRNP K regulates inflammatory gene expression by mediating splicing pattern of transcriptional factors

HnRNP K is a heterogeneous nuclear ribonucleoprotein and has been identified as an oncogene in most solid tumors via regulating gene expression or alternative splicing of genes by binding both DNA and pre-mRNA. However, how hnRNP K affects tumorigenesis and regulates the gene expression in cervical cancer (CESC) remains to be elucidated. In these data, higher expression of hnRNP K was observed in CESC and was negatively correlated with the patient survival time. We then overexpressed hnRNP K (hnRNP K-OE) and found that its overexpression promoted cell proliferation in HeLa cells (P = 0.0052). Next, global transcriptome sequencing (RNA-seq) experiments were conducted to explore gene expression and alternative splicing profiles regulated by hnRNP K. It is shown that upregulated genes by hnRNP K-OE were associated with inflammatory response and an apoptotic process of neuron cells, which involves in cancer. In addition, the alternative splicing of those genes regulated by hnRNP K-OE was associated with transcriptional regulation. Analysis of the binding features of dysregulated transcription factors (TFs) in the promoter region of the inflammatory response genes regulated by hnRNP K revealed that hnRNP K may modulate the expression level of genes related to inflammatory response by influencing the alternative splicing of TFs. Among these hnRNP K-TFs-inflammatory gene regulatory networks, quantitative reverse transcription polymerase chain reaction (RT-qPCR) experiments and gene silencing were conducted to verify the hnRNP K-IRF1-CCL5 axis. In conclusion, the hnRNP K-TFs-inflammatory gene regulatory axis provides a novel molecular mechanism for hnRNP K in promoting CESC and offers a new therapeutic target.

The Emerging Role of MMP12 in the Oral Environment

Matrix metalloproteinase-12 (MMP12), or macrophage metalloelastase, plays important roles in extracellular matrix (ECM) component degradation. Recent reports show MMP12 has been implicated in the pathogenesis of periodontal diseases. To date, this review represents the latest comprehensive overview of MMP12 in various oral diseases, such as periodontitis, temporomandibular joint dysfunction (TMD), orthodontic tooth movement (OTM), and oral squamous cell carcinoma (OSCC). Furthermore, the current knowledge regarding the distribution of MMP12 in different tissues is also illustrated in this review. Studies have implicated the association of MMP12 expression with the pathogenesis of several representative oral diseases, including periodontitis, TMD, OSCC, OTM, and bone remodelling. Although there may be a potential role of MMP12 in oral diseases, the exact pathophysiological role of MMP12 remains to be elucidated. Understanding the cellular and molecular biology of MMP12 is essential, as MMP12 could be a potential target for developing therapeutic strategies targeting inflammatory and immunologically related oral diseases.

hnRNP K induces HPV16 oncogene expression and promotes cervical cancerization

PURPOSE

This study aims to explore the expression of hnRNP K in cervical carcinogenesis and to investigate the regulatory role of hnRNP K on HPV16 oncogene expression as well as biological changes in cervical cancer cells.

METHODS

In total 1042 subjects, including 573 with the normal cervix and 469 with different grades of cervical lesions were enrolled in this study to explore the association between hnRNP K and HPV16 oncogene expression in cervical carcinogenesis. Additionally, the Gene Omnibus (GEO) database was used to analyze hnRNP K mRNA expression in cervical cancerization. Meanwhile, the effects of hnRNP K on cell biological functions and HPV16 oncogene expression were investigated in Siha cells. Moreover, Function analyses were conducted using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases after ChIP-seq.

RESULTS

hnRNP K was highly expressed in cervical cancer and precancerous lesions, and positively correlated with HPV16 E6, but negatively correlated with HPV16 E2 and HPV16 E2/E6 ratio. hnRNP K induced cell proliferation, inhibited apoptosis and caused cell cycle arrest in the S phase, and particularly increased HPV16 E6 protein expression.

CONCLUSION

This study revealed that hnRNP K overexpression has important warning significance for the malignant transformation of cervical lesions, and could be used as a potential therapeutic target for inhibiting the carcinogenicity of HPV16 and prevention of cervical carcinogenesis.

Removal of nonspecific binding proteins is required in co-immunoprecipitation with nuclear proteins

Whether protein samples should be pretreated to remove nonspecific binding proteins in co-immunoprecipitation (CO-IP) is controversial. In this work, nonspecific binding of proteins to agarose beads was found to be greater than that to magnetic beads. The nonspecific binding was increased with the decrease of ion concentrations but reduced by Nonidet P40. Western blot indicated that p65 and β-actin were present as nonspecifically bound protein to the beads. p53 and β-actin were present in the CO-IP precipitates of nuclear proteins but pretreatment cleared the nonspecifically pulled down p53 and β-actin. These data suggest that magnetic beads are better for CO-IP, but preclearing is necessary to minimize false positive regardless of which bead is used, particularly for nuclear proteins.

The hnRNPK/A1/R/U Complex Regulates Gene Transcription and Translation and is a Favorable Prognostic Biomarker for Human Colorectal Adenocarcinoma

Heterogeneous nuclear ribonucleoproteins (hnRNPs) are emerging as a crucially important protein family in tumors. However, it is unclear which family members are essential for cancer progression, and their diverse expression patterns and prognostic values are rarely reported. In this work, we found that the expression levels of hnRNPs were all upregulated in colon adenocarcinoma (COAD) and rectal adenocarcinoma (READ) tissues. Immunohistochemical staining revealed that hnRNPA1, hnRNPA2B1, hnRNPC, hnRNPK, hnRNPR, and hnRNPU are overexpressed in colorectal adenocarcinoma. Additionally, the promoter methylation levels of hnRNPs were significantly elevated or decreased, and multiple genetic alterations of hnRNPs were found in colorectal adenocarcinoma patients. Correlation analysis showed that the expression levels of hnRNPs were positively correlated with each other. Furthermore, we demonstrated that high expressions of hnRNPA1, hnRNPK, hnRNPR, and hnRNPU were associated with better overall survival rates for colorectal adenocarcinoma patients. The co-expression network and functional prediction analysis indicated that hnRNPK/A1/R/U was involved in cellular gene transcription and translation. Moreover, hnRNPK/A1/R/U complex was identified and confirmed by mass spectrometry and co-immunoprecipitation. RNA sequencing analysis revealed that the transcription factor hnRNPK regulated transcription and translation of related genes. Finally, through establishment of stable cell lines in vitro, we verified that hnRNPK was a favorable factor in human colorectal adenocarcinoma which promoted immune cell infiltration and inhibited tumor growth. Our findings illustrate that the hnRNPK/A1/R/U complex is a favorable prognostic biomarker for human colorectal adenocarcinoma. Targeting hnRNPK during transcription and translation could be a promising therapeutic strategy for colorectal adenocarcinoma treatment.

hnRNPK-derived cell-penetrating peptide inhibits cancer cell survival

hnRNPK is a multifunctional protein that plays an important role in cancer cell proliferation and metastasis via its RNA- and DNA-binding properties. Previously we showed that cell-penetrating peptides derived from the RGG RNA-binding domain of SAFA (hnRNPU) disrupt cancer cell proliferation and survival. Here we explore the efficacy of a peptide derived from the RGG domain of hnRNPK. This peptide acts in a dominant-negative manner on several hnRNPK functions to induce death of multiple types of cancer cells. The peptide phenocopies the effect of hnRNPK knockdown on its mRNA-stability targets such as KLF4 and EGR1 and alters the levels and locations of long non-coding RNAs (lncRNAs) and proteins required for nuclear and paraspeckle formation and function. The RGG-derived peptide also decreases euchromatin as evidenced by loss of active marks and polymerase II occupancy. Our findings reveal the potential therapeutic utility of the hnRNPK RGG-derived peptide in a range of cancers.

Estimation of salivary matrix metalloproteinases- 12 (MMP- 12) levels among patients presenting with oral submucous fibrosis and oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma is a global threat and accounts for approximately 90% of malignant oral lesions. The emergence of oral carcinoma is linked to precancerous lesions, which act as precursors of the disease. Matrix metalloproteinases appear to play a significant role in the pathogenesis of both precancerous conditions and oral malignancies due to their participation in remodeling of the extracellular matrix.

METHODOLOGY

This is an analytical study conducted at Dow University of Health Sciences, Pakistan. Unstimulated saliva samples were collected from healthy, oral submucous fibrosis and oral squamous cell carcinoma patients. The level of MMP-12 was estimated using enzyme-linked immunosorbent assay. One-way Analysis of variance was run to determine if MMP-12 levels differ between the three groups, which was preceded by post hoc Tuckey test. MMP-12 cut off values were determined using Receiver operating characteristic curve.

RESULTS

A significant difference in salivary MMP-12 expression was observed in OSF and OSCC (p < 0.001). The expression of salivary MMP-12 was higher in OSF and OSCC patients as compared to the healthy group (p < 0.001). The mean MMP-12 expression in OSCC appeared higher than in OSF cases (p < 0.05). MMP-12 value of [Formula: see text] 4.05 ng/ml and [Formula: see text] 4.20 ng/ml is predictive of OSF and OSCC respectively, with 100% sensitivity and specificity (p < 0.001).

CONCLUSION

Increased expression of MMP-12 appears as the healthy patient advances to OSF and OSCC. The study results also demonstrate higher MMP-12 expression in OSCC patients as compared to OSF. Therefore, the estimation of salivary MMP-12 serves as a valuable non-invasive early diagnostic tool in diagnosing oral submucous fibrosis and oral squamous cell carcinoma.

Transcriptomic and microRNA Expression Profiles Identify Biomarkers for Predicting Neo-Chemoradiotherapy Response in Esophageal Squamous Cell Carcinomas (ESCC)

Neo-chemoradiotherapy (nCRT) before surgery is a standard treatment for locally advanced esophageal cancers. However, the treatment outcome of nCRT varied with different patients. This study aimed to identify potential biomarkers for prediction of nCRT-response in patients with esophageal squamous cell carcinoma (ESCC). Microarray datasets of nCRT responder and non-responder samples (access number GSE45670 and GSE59974) of patients with ESCC were downloaded from Gene Expression Omnibus (GEO) database. The mRNA expression profiles of cancer biopsies from four ESCC patients were analyzed before and after nCRT. Differentially expressed genes (DEGs) and miRNAs were screened between nCRT responder and non-responder ESCC samples. Functional enrichment analysis was conducted for these DEGs followed by construction of protein-protein interaction (PPI) network and miRNA-mRNA regulatory network. Finally, univariate survival analysis was performed to identify candidate biomarkers with prognostic values in ESCC. We identified numerous DEGs and differentially expressed miRNAs from nCRT responder group. GO and KEGG analysis showed that the dysregulated genes were mainly involved in biological processes and pathways, including "response to stimulus", "cellular response to organic substance", "regulation of signal transduction", "AGE-RAGE signaling pathway in diabetic complications", and "steroid hormone biosynthesis". After integration of PPI network and miRNA-mRNA network analysis, we found eight genes, TNF, AKR1C1, AKR1C2, ICAM1, GPR68, GNB4, SERPINE1 and MMP12, could be candidate genes associated with disease progression. Univariate cox regression analysis showed that there was no significant correlation between dysregulated miRNAs (such as hsa-miR-34b-3p, hsa-miR-127-5p, hsa-miR-144-3p, and hsa-miR-486-5p, et al.) and overall survival of ESCC patients. Moreover, abnormal expression of MMP12 was significantly correlated with pathological degree, TNM stage, lymph nodes metastasis, and overall survival of ESCC patients (p < 0.05). Taken together, our study identified that MMP12 might be a useful tumor biomarker and therapeutic target for ESCC.

hnRNPK-regulated LINC00263 promotes malignant phenotypes through miR-147a/CAPN2

Malignant characteristics of cancers, represented by rapid cell proliferation and high metastatic potential, are a major cause of high cancer-related mortality. As a multifunctional RNA-binding protein, heterogeneous nuclear ribonucleoprotein K (hnRNPK) is closely associated with cancer progression in various types of cancers. In this study, we sought to identify hnRNPK-regulated long intergenic non-coding RNAs (lincRNAs) that play a critical role in the regulation of cancer malignancy. We found that hnRNPK controlled malignant phenotypes including invasiveness, proliferation, and clonogenicity. RNA sequencing and functional studies revealed that LINC00263, a novel target of hnRNPK, is involved in the oncogenic functions of hnRNPK. Knockdown of LINC00263 mitigated the malignant capabilities. Conversely, increased malignant phenotypes were observed in LINC00263-overexpressing cells. Since LINC00263 was mainly localized in the cytosol and highly enriched in Argonaute 2-immunoprecipitation (Ago2-IP), we hypothesized that LINC00263 acts as a competitive endogenous RNA (ceRNA), and thus sought to identify LINC00263-associated microRNAs. Using small RNA sequencing followed by antisense oligonucleotide pull-down, miR-147a was selected for further study. We found that miR-147a negatively regulates LINC00263 via direct interaction, thus suppressing malignant capabilities. Moreover, knockdown of hnRNPK and LINC00263 upregulated miR-147a, indicating that LINC00263 serves as a ceRNA for miR-147a. By analyzing RNA sequencing data and miRNA target prediction, calpain 2 (CAPN2) was identified as a putative target of miR-147a. Ago2-IP and luciferase reporter assay revealed that miR-147a suppressed CAPN2 expression by directly binding to the 3′UTR of CAPN2 mRNA. In addition, we found that the weakened malignant capabilities following knockdown of hnRNPK or LINC00263 were restored by miR-147a inhibition or CAPN2 overexpression. Furthermore, our findings were validated in various other types of cancer cells including lung cancer, colorectal cancer, neuroblastoma, and melanoma. Collectively, we demonstrate that hnRNPK-regulated LINC00263 plays an important role in cancer malignancy by acting as a miR-147a decoy and thus upregulating CAPN2.

The role of chromodomain helicase DNA binding protein 1 (CHD1) in promoting an invasive prostate cancer phenotype

BACKGROUND

Prostate cancer (PCa) phenotypes vary from indolent to aggressive. Molecular subtyping may be useful in predicting aggressive cancers and directing therapy. One such subtype involving deletions of chromodomain helicase DNA binding protein 1 (CHD1), a tumor suppressor gene, are found in 10-26% of PCa tumors. In this study, we evaluate the functional cellular effects that follow CHD1 deletion.

METHODS

CHD1 was knocked out (KO) in the non-tumorigenic, human papillomavirus 16 (HPV16)-immortalized prostate epithelial cell line, RWPE-1, using CRISPR/Cas9. In vitro assays such as T7 endonuclease assay, western blot, and sequencing were undertaken to characterize the CHD1 KO clones. Morphologic and functional assays for cell adhesion and viability were performed. To study expression of extracellular matrix (ECM) and adhesion molecules, a real-time (RT) profiler assay was performed using RWPE-1 parental, non-target cells (NT2) and CHD1 KO cells.

RESULT

Compared to parental RWPE-1 and non-target cells (NT2), the CHD1 KO cells had a smaller, rounder morphology and were less adherent under routine culture conditions. Compared to parental cells, CHD1 KO cells showed a reduction in ECM and adhesion molecules as well as a greater proportion of viable suspension cells when cultured on standard tissue culture plates and on plates coated with laminin, fibronectin or collagen I. CHD1 KO cells showed a decrease in the expression of secreted protein acidic and rich in cysteine (SPARC), matrix metalloproteinase 2 (MMP2), integrin subunit alpha 2 (ITGA2), integrin subunit alpha 5 (ITGA5), integrin subunit alpha 6 (ITGA6), fibronectin (FN1), laminin subunit beta-3 precursor (LAMB3), collagen, tenascin and vitronectin as compared to parental and NT2 cells.

CONCLUSION

These data suggest that in erythroblast transformation specific (ETS) fusion-negative, phosphatase and tensin homolog (PTEN) wildtype PCa, deletion of CHD1 alters cell-cell and cell-matrix adhesion dynamics, suggesting an important role for CHD1 in the development and progression of PCa.

Heterogeneous nuclear ribonucleoprotein K is overexpressed and contributes to radioresistance irrespective of HPV status in head and neck squamous cell carcinoma

Radiotherapy is a major treatment option for head and neck squamous cell carcinoma (HNSCC). However, the success of radiotherapy is limited by tumor cell resistance to ionizing radiation (IR). Clinical studies have demonstrated an overall improved prognosis and higher susceptibility to radiotherapy of high‑risk human papillomavirus (HPV)‑associated HNSCC compared with classic HNSCC, as well as worse overall survival for male HNSCC patients. Overexpression of heterogeneous nuclear ribonucleoprotein (hnRNP) K has been associated with resistance to radiotherapy in melanoma and colorectal carcinoma. The aim of the present study was to analyze the impact of hnRNP K expression on the aggressiveness and radioresistance of HNSCC with respect to patient sex and HPV status. Immunohistochemical staining of HNSCC tissue specimens revealed elevated hnRNP K levels compared with those in the non‑neoplastic epithelium. Cytoplasmic hnRNP K accumulation was associated with advanced tumor stage and male sex. Exposure of HNSCC cells to IR was followed by rapid upregulation of hnRNP K at the protein level, along with re‑localization from the tumor cell nucleus to the cytoplasm. siRNA‑based knockdown of hnRNP K induced apoptosis and abolished tumor formation after xenotransplantation of HNSCC cells onto the chick egg chorioallantoic membrane (CAM). The observed effects were independent of the respective HPV status of the cell lines. These results indicated a tumorigenic and anti‑apoptotic role of hnRNP K in HNSCC, which appeared to be enhanced in male patients and contributed to the radioresistance of these tumors. However, the radioprotective effects of hnRNP K were found to be independent of the tumor's HPV status.

Five extracellular matrix-associated genes upregulated in oral tongue squamous cell carcinoma: An integrated bioinformatics analysis

Despite advancements in treatment regimens, the mortality rate of patients with oral tongue squamous cell carcinoma (OTSCC) is high. In addition, the signaling pathways and oncoproteins involved in OTSCC progression remain largely unknown. Therefore, the aim of the present study was to identify specific prognostic marker for patients at a high risk of developing OTSCC. The present study used four original microarray datasets to identify the key candidate genes involved in OTSCC pathogenesis. Expression profiles of 93 OTSCC tissues and 76 normal tissues from GSE9844, GSE13601, GSE31056 and GSE75538 datasets were investigated. Differentially expressed genes (DEGs) were determined, and gene ontology enrichment and gene interactions were analyzed. The four GSE datasets reported five upregulated and six downregulated DEGs. Five upregulated genes (matrix metalloproteinase 1, 3, 10 and 12 and laminin subunit gamma 2) were localized in the extracellular region of cells and were associated with extracellular matrix disassembly. Furthermore, analysis for The Cancer Genome Atlas database revealed that the aforementioned five upregulated genes were also highly expressed in OTSCC and head and neck squamous cell carcinoma tissues. These results demonstrated that the five upregulated genes may be considered as potential prognostic biomarkers of OTSCC and may serve at understanding OTSCC progression. Upregulated DEGs may therefore represent valuable therapeutic targets to prevent or control OTSCC pathogenesis.

The emerging roles of hnRNPK

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an DNA/RNA-binding protein and regulates a wide range of biological processes and disease pathogenesis. It contains 3 K-homologous (KH) domains, which are conserved in other RNA-binding proteins, mediate nucleic acid binding activity, and function as an enhancer or repressor of gene transcription. Phosphorylation of the protein alters its regulatory function, which also enables the protein to serve as a docking platform for the signal transduction proteins. In terms of the function of hnRNPK, it is central to many cellular events, including long noncoding RNA (lncRNA) regulation, cancer development and bone homoeostasis. Many studies have identified hnRNPK as an oncogene, where it is overexpressed in cancer tissues compared with the nonneoplastic tissues and its expression level is related to the prognosis of different types of host malignancies. However, hnRNPK has also been identified as a tumour suppressor, as it is important for the activation of the p53/p21 pathway. Recently, the protein is also found to be exclusively related to the regulation of paraspeckles and lncRNAs such as Neat1, Lncenc1 and Xist. Interestingly, hnRNPK has been found to associate with the Kabuki-like syndrome and Au-Kline syndrome with prominent skeletal abnormalities. In vitro study revealed that the hnRNPK protein is essential for the formation of osteoclast, in line with its importance in the skeletal system.

Aromatase-induced endogenous estrogen promotes tumour metastasis through estrogen receptor-α/matrix metalloproteinase 12 axis activation in castration-resistant prostate cancer

Castration-resistant prostate cancer (CRPC) following androgen deprivation therapy remains a major obstacle advanced prostate cancer management. Aromatase catalyzes estrogen from androgens, yet the role of aromatase-generated endogenous estrogen in CRPC is poorly understood. In this study, we assessed the expression and function of aromatase in CRPC. We found that aromatase expression was significantly increased in CRPC tissues and cell lines. In some prostate cancer cell lines, aromatase was predominantly expressed in CD44⁺ subsets. Bicalutamide treatment significantly increased aromatase expression, and CYP19A1 expression positively correlated with estrogen responses and epithelial-mesenchymal transition. Aromatase knockdown in PC3 cells reduced invasiveness and decreased metastasis-related gene expression. The aromatase inhibitor, letrozole, attenuated tumour metastasis in castrated PC3-xenograft mice. Mechanistically, aromatase-induced endogenous estrogen promoted estrogen receptor-α (ERα) binding to matrix metalloproteinase 12 (MMP12) promoter estrogen response element (ERE). MMP12 co-localized with CD44 on the cell membrane and MMP12 knockdown significantly reduced estradiol-induced PC3 invasion. Taken together, our findings indicated that increased endogenous estrogen, catalysed by elevated aromatase levels, enhanced MMP12 expression via ERα, participated in CRPC progression and promoted tumour metastasis. Thus, aromatase represents a potential novel therapeutic target for CRPC.

A novel ZRS variant causes preaxial polydactyly type I by increased sonic hedgehog expression in the developing limb bud

Purpose

Preaxial polydactyly (PPD) is a common congenital hand malformation classified into four subtypes (PPD I–IV). Variants in the zone of polarizing activity regulatory sequence (ZRS) within intron 5 of the LMBR1 gene are linked to most PPD types. However, the genes responsible for PPD I and the underlying mechanisms are unknown.

Methods

A rare large four-generation family with isolated PPD I was subjected to genome-wide genotyping and sequence analysis. In vitro and in vivo functional studies were performed in Caco-2 cells, 293T cells, and a knockin transgenic mouse model.

Results

A novel g.101779T>A (reference sequence: NG_009240.2; position 446 of the ZRS) variant segregates with all PPD I–affected individuals. The knockin mouse with this ZRS variant exhibited PPD I phenotype accompanying ectopic and excess expression of Shh. We confirmed that HnRNP K can bind the ZRS and SHH promoters. The ZRS mutant enhanced the binding affinity for HnRNP K and upregulated SHH expression.

Conclusion

Our results identify the first PPD I disease-causing variant. The variant leading to PPD I may be associated with enhancing SHH expression mediated by HnRNP K. This study adds to the ZRS-associated syndromes classification system for PPD and clarifies the underlying molecular mechanisms.

Implication of viral microRNAs in the genesis and diagnosis of Epstein-Barr virus-associated tumors

The Epstein-Barr virus (EBV) is tightly associated with a variety of human tumors, including Burkitt lymphoma and acquired immune deficiency syndrome-related lymphoma of B-cell origin, as well as nasopharyngeal carcinoma and gastric cancer of epithelial origin. The virus latently infects the host cells and expresses proteins and non-coding RNAs to achieve malignancy. MicroRNAs (miRNAs or miRs) are small RNAs consisting of 19-25 nucleotides, which directly bind to the 3'-untranslated region of mRNAs to promote degradation and inhibit translation of mRNAs. EBV-encoded miRs are generated from two regions of the viral genome, within the apoptosis regulator BHRF1 gene locus and near the BamHI A region in a latency type-dependent manner. In addition, EBV-encoded miRs epigenetically regulate the expression of molecules that are effectors of the cell cycle progression, migration, apoptosis and innate immunity, serving a vital role in supporting viral replication and occurrence of EBV-associated tumors. The feasibility of using such miRs as biomarkers for the diagnosis and prognosis of EBV-associated tumors is currently under investigation.

Role of heterogeneous nuclear ribonucleoprotein K in tumor development

Heterogeneous nuclear ribonucleoprotein K (hnRNP K) is an RNA/DNA special binding protein that participates in regulating the expression of related genes, transcription, RNA alternative splicing, translation, posttranslational modification, cell signal transduction, cell movement, interacts with ncRNAs, and induces angiogenesis. Moreover, several cellular functions forcefully indicated that hnRNP K participates in tumorigenesis. Numerous studies indicated hnRNP K is aberrantly elevated in multiple tumors. In addition, hnRNP K abnormal accumulation in cytoplasmic is also associated with poor prognosis. This suggests that hnRNP K may play a role in the development and progression of tumors. However, related studies demonstrated that hnRNP K acts as a tumor suppressor to suppress tumor formation. Therefore, this paper aims to explore the role of hnRNPK in tumors.

hnRNPK S379 phosphorylation participates in migration regulation of triple negative MDA-MB-231 cells

We have previously identified a novel Aurora-A-mediated Serine 379 (S379) phosphorylation of a poly(C)-binding protein, hnRNPK, the overexpression of which is frequently observed in various cancers. It is known that the oncogenic Aurora-A kinase promotes the malignancy of cancer cells. This study aims to investigate the unexplored functions of hnRNPK S379 phosphorylation using MDA-MB-231 cells, a triple negative breast cancer cell that has amplification of the Aurora-A kinase gene. Accordingly, we established two cell lines in which the endogenous hnRNPK was replaced with either S379D or S379A hnRNPK respectively. Notably, we found that a phosphorylation-mimic S379D mutant of hnRNPK suppressed cell migration and, conversely, a phosphorylation-defective S379A mutant promoted migration. Moreover, Twist was downregulated upon hnRNPK S379 phosphorylation, whereas β-catenin and MMP12 were increased when there was loss of hnRNPK S379 phosphorylation in MDA-MB-231 cells. Furthermore, S379A hnRNPK increases stability of β-catenin in MDA-MB-231 cells. In conclusion, our results suggest that hnRNPK S379 phosphorylation regulates migration via the EMT signaling pathway.

The prognostic values of matrix metalloproteinases in ovarian cancer

Objective

To investigate the prognostic significance of 23 matrix metalloproteinase (MMP) genes in patients diagnosed with ovarian carcinoma.

Methods

The prognostic significance of 23 MMP genes in patients diagnosed with ovarian carcinoma was investigated using the Kaplan–Meier plotter (KM plotter), which uses the gene expression data and overall survival information of patients with ovarian cancer that were downloaded from the Gene Expression Omnibus, Cancer Biomedical Informatics Grid and The Cancer Genome Atlas cancer datasets. The correlation between mRNA levels of individual MMPs (MMP2, MMP9, MMP10, MMP12, MMP13 and MMP25) and clinicopathological features (histological subtype, pathological grade and clinical stage) were investigated. The MMP protein level profiles in normal ovarian tissues and ovarian cancer tissues were examined using the Human Protein Atlas database.

Results

The results showed that high mRNA levels of MMP2 and MMP13 were associated with a worse overall survival in patients with ovarian cancer, whereas high mRNA levels of MMP9, MMP10, MMP12 and MMP25 were associated with a better overall survival. The protein levels of MMP2, MMP9, MMP10 and MMP25 in ovarian cancer tissues were elevated compared with normal ovarian tissues.

Conclusions

This study demonstrated that MMPs can be a reliable prognostic biomarker for ovarian cancer.

Copper nanoparticle-induced uterine injury in female rats

Copper nanoparticles (Cu-NPs) have been used increasingly in various products and applications. Although recent studies have reported that exposure to Cu-NPs leads to organ accumulation and obvious toxicity, it remains unclear whether Cu-NPs can be translocated to and cause damage in the uterus. In this study, we investigated the potential for uterine injury and gene expression patterns in female rats exposed to 3.12, 6.25, or 12.5 mg/kg/d Cu-NPs via intraperitoneal injection for 14 consecutive days. The results indicated that exposure to Cu-NPs led to significant decreases in the relative uterine weight coefficients and increases in inflammatory cell infiltration, mitochondrial swelling and vacuolization, shortened and reduced endometrial epithelial cell microvilli, and apoptosis. Furthermore, exposure to Cu-NPs increased malondialdehyde (MDA) accumulation and decreased superoxide dismutase (SOD) levels. Signal transduction mechanism studies indicated that exposure to Cu-NPs activated caspases 3, 8, and 9 and BH3 interacting domain death agonist (tBid), reduced B cell leukemia/lymphoma 2 (Bcl-2) expression, and increased the expression of apoptotic peptidase activating factor 1 (Apaf-1), BCL2-associated X, apoptosis regulator (Bax), and cytochrome c. A microarray analysis revealed significant alterations in the expression of 963 genes; of these, 622 were upregulated and 341 were downregulated. The results of further evaluations of some altered genes, including matrix metallopeptidase 12 (Mmp12), using quantitative RT-PCR agreed with the microarray findings. These results provide strong evidence that Cu-NPs can trigger both intrinsic and extrinsic apoptotic pathways to mediate uterine injury, resulting in oxidative stress-related changes in gene expression.

Irradiation-induced dynamic changes of gene signatures reveal gain of metastatic ability in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC), arising from the nasopharynx epithelium, is prevalent among South and East Asia. The radiotherapy is the primary treatment for NPC patients. However, the acquired radioresistance dramatically diminishes the therapeutic effect of radiotherapy. Meanwhile, recurrence and metastasis always occur in line with the radioresistance, but the underlying mechanisms are still unclear. In this study, we established two radioresistant NPC cell lines, CNE1R and SUNE1R, by sequentially irradiated parental CNE1 and SUNE1 cells up to a clinical treatment dose of 72 Gy. A transcriptome profile analysis of CNE1R and CNE1 reveals that activated oncogenic pathways are highly enriched in CNE1R. As the result, CNE1R showed higher proliferation rate but lower apoptosis rate after irradiation, and enhanced metastasis ability in comparison with CNE1. Significantly, a group of metastasis associated genes were increased in CNE1R while the irradiation proceeded, including several matrix metallopeptidase (MMP) members, especially MMP10 and MMP13. With further analysis, we found both MMP10 and MMP13 are highly upregulated in metastatic head and neck cancer specimens compared to non-metastatic ones. More importantly, patients with lower expression of both MMP10 and MMP13 showed a better five-year survival than the double high group. Our findings unveiled the potential mechanisms of radioresistance related metastasis in NPC patients, and the increase of MMP10 and MMP13 may serve as high risk factors for metastasis during radiotherapy.

O-GlcNAc-induced nuclear translocation of hnRNP-K is associated with progression and metastasis of cholangiocarcinoma

O‐GlcNAcylation is a key post‐translational modification that modifies the functions of proteins. Associations between O‐GlcNAcylation, shorter survival of cholangiocarcinoma (CCA) patients, and increased migration/invasion of CCA cell lines have been reported. However, the specific O‐GlcNAcylated proteins (OGPs) that participate in promotion of CCA progression are poorly understood. OGPs were isolated from human CCA cell lines, KKU‐213 and KKU‐214, using a click chemistry‐based enzymatic labeling system, identified using LC‐MS/MS, and searched against an OGP database. From the proteomic analysis, a total of 21 OGPs related to cancer progression were identified, of which 12 have not been previously reported. Among these, hnRNP‐K, a multifaceted RNA‐ and DNA‐binding protein known as a pre‐mRNA‐binding protein, was one of the most abundantly expressed, suggesting its involvement in CCA progression. O‐GlcNAcylation of hnRNP‐K was further verified by anti‐OGP/anti‐hnRNP‐K immunoprecipitations and sWGA pull‐down assays. The perpetuation of CCA by hnRNP‐K was evaluated using siRNA, which revealed modulation of cyclin D1, XIAP, EMT markers, and MMP2 and MMP7 expression. In native CCA cells, hnRNP‐K was primarily localized in the nucleus; however, when O‐GlcNAcylation was suppressed, hnRNP‐K was retained in the cytoplasm. These data signify an association between nuclear accumulation of hnRNP‐K and the migratory capabilities of CCA cells. In human CCA tissues, expression of nuclear hnRNP‐K was positively correlated with high O‐GlcNAcylation levels, metastatic stage, and shorter survival of CCA patients. This study demonstrates the significance of O‐GlcNAcylation on the nuclear translocation of hnRNP‐K and its impact on the progression of CCA.

ACVR1C/SMAD2 signaling promotes invasion and growth in retinoblastoma

Retinoblastoma is the most common intraocular cancer in children. While the primary tumor can often be treated by local or systemic chemotherapy, metastatic dissemination is generally resistant to therapy and remains a leading cause of pediatric cancer death in much of the world. In order to identify new therapeutic targets in aggressive tumors, we sequenced RNA transcripts in five snap frozen retinoblastomas which invaded the optic nerve and five which did not. A three-fold increase was noted in mRNA levels of ACVR1C/ALK7, a type I receptor of the TGF-β family, in invasive retinoblastomas, while downregulation of DACT2 and LEFTY2, negative modulators of the ACVR1C signaling, was observed in most invasive tumors. A two- to three-fold increase in ACVR1C mRNA was also found in invasive WERI Rb1 and Y79 cells as compared to non-invasive cells in vitro. Transcripts of ACVR1C receptor and its ligands (Nodal, Activin A/B, and GDF3) were expressed in six retinoblastoma lines, and evidence of downstream SMAD2 signaling was present in all these lines. Pharmacological inhibition of ACVR1C signaling using SB505124, or genetic downregulation of the receptor using shRNA potently suppressed invasion, growth, survival, and reduced the protein levels of the mesenchymal markers ZEB1 and Snail. The inhibitory effects on invasion, growth, and proliferation were recapitulated by knocking down SMAD2, but not SMAD3. Finally, in an orthotopic zebrafish model of retinoblastoma, a 55% decrease in tumor spread was noted (p=0.0026) when larvae were treated with 3 μM of SB505124, as compared to DMSO. Similarly, knockdown of ACVR1C in injected tumor cells using shRNA also resulted in a 54% reduction in tumor dissemination in the zebrafish eye as compared to scrambled shRNA control (p=0.0005). Our data support a role for the ACVR1C/SMAD2 pathway in promoting invasion and growth of retinoblastoma.

Carcinoembryonic antigen as a marker of radioresistance in colorectal cancer: a potential role of macrophages

Background

We sought to identify the carcinoembryonic antigen (CEA) as a marker of radioresistance in rectal cancer.

Methods

From July 1997 to January 2008, 104 patients with stage II or III rectal cancer who were treated with post-operative radiotherapy (PORT) were included in this study. The doses of radiotherapy ranged from 45 to 54.6 Gy. The CEA levels were measured before surgery. We analyzed the actuarial rates of overall survival (OS), distant metastasis (DM), and local recurrence (LR) using Kaplan-Meier curves. Multivariate analyses were performed with Cox regression models. We used THP-1 monocyte cell lines for macrophage differentiation (M0, M1 or M2). The RNA extracted from the macrophages was analyzed via a genomic method in the core laboratory. The radiosensitivities of CEA-rich LS1034 cells were compared between cells with and without the conditioned media from CEA-stimulated macrophages.

Results

Preoperative CEA levels ≥10 ng/mL were independent predictive factors for OS (p = 0.005), DM (p = 0.026), and LR (p = 0.004). The OS rates among the patients with pretreatment CEA levels < 10 ng/mL and ≥10 ng/mL were 64.5% and 35.9% (p = 0.004), respectively. The corresponding rates of DM were 40.6% and 73.1% (p = 0.024). The corresponding rates of LR were 6.6% and 33.9% (p = 0.002). In the M0 macrophages, exogenous CEA elicited a dose-response relationship with M2 differentiation. In the CEA-stimulated M0 cells, some mRNAs were upregulated by as much as 5-fold, including MMP12, GDF15, and JAG1. In the CEA-stimulated M2 cells, a 4-fold up-regulation of GADD45G mRNA was noted. The conditioned media from the CEA-stimulated M2 cells elicited an increase in the numbers of LS180, SW620, and LS1034 cells after irradiation. CEA caused the M2 differentiation of the macrophages.

Conclusion

Pretreatment CEA levels ≥10 ng/mL are a significant risk factor for OS, DM, and LR following PORT for rectal cancer. CEA causes radioresistance in the presence of M2 macrophages. More comprehensive examinations prior to surgery and intensive adjuvant therapy are suggested for patients with CEA levels ≥10 ng/mL. Further studies of these mechanisms are needed.

Matrix metalloproteinase 12 promotes tumor propagation in the lung

OBJECTIVE

Past studies are inconsistent with regard to the role of matrix metalloproteinase 12 in lung tumorigenesis. This is due, in part, to differential tumorigenesis based on tumor-derived versus immune-derived matrix metalloproteinase 12 expression. Our study aims to thoroughly dissect the role of matrix metalloproteinase 12 in lung tumorigenesis.

METHODS

We tested matrix metalloproteinase 12 expression and the association with prognosis using a tissue array and a published non-small cell lung cancer gene expression database. In addition, we characterized the contribution of matrix metalloproteinase 12 to tumor propagation in the lung using a series of in vitro and in vivo studies.

RESULTS

Tumor cells of a diverse set of human lung cancers stained positive for matrix metalloproteinase 12, and high matrix metalloproteinase 12 mRNA levels in the tumor were associated with reduced survival. The lung microenvironment stimulated endogenous production of matrix metalloproteinase 12 in lung cancer cells (human 460 lung cancer cell line, Lewis lung carcinoma). In vitro, matrix metalloproteinase 12 knockout Lewis lung carcinoma and Lewis lung carcinoma cells had the same proliferation rate, but Lewis lung carcinoma showed increased invasiveness. In vivo, deficiency of matrix metalloproteinase 12 in Lewis lung carcinoma cells, but not in the host, reduced tumor growth and invasiveness.

CONCLUSIONS

We suggest that tumor cell-derived matrix metalloproteinase 12 promotes tumor propagation in the lung and that in the context of pulmonary malignancies matrix metalloproteinase 12 should further be tested as a potential novel therapeutic target.

Down-regulation of DAB2IP promotes colorectal cancer invasion and metastasis by translocating hnRNPK into nucleus to enhance the transcription of MMP2

DOC-2/DAB2 interacting protein (DAB2IP) is a RasGAP protein that shows a suppressive effect on cancer progression. Our previous study showed the involvement of transcription regulation of DAB2IP in metastasis of colorectal cancer (CRC). However, the molecular mechanisms of DAB2IP in regulating the progression of CRC need to be further explored. Here, we identified heterogeneous nuclear ribonucleoprotein K (hnRNPK) and matrix metalloproteinase 2 (MMP2) as vital downstream targets of DAB2IP in CRC cells by two-dimensional fluorescence difference gel electrophoresis and cDNA microassay, respectively. Mechanistically, down-regulation of DAB2IP increased the level of hnRNPK through MAPK/ERK signaling pathway. Subsequently, translocation of hnRNPK into nucleus enhanced the transcription activity of MMP2, and therefore promoted invasion and metastasis of CRC. Down-regulation of DAB2IP correlated negatively with hnRNPK and MMP2 expressions in CRC tissues. In conclusion, our study elucidates a novel mechanism of the DAB2IP/hnRNPK/MMP2 axis in the regulation of CRC invasion and metastasis, which may be a potential therapeutic target.

Knockdown of MMP12 inhibits the growth and invasion of lung adenocarcinoma cells

Matrix metalloproteinase-12 (MMP12) is involved in many pathological processes including cancer. The expression and function of MMP12 in lung adenocarcinoma (LAC) remain unclear. The present study aimed to investigate the correlation of MMP12 expression with LAC patients and clarify its role in growth and invasion of LAC cells. The expression of MMP12 in human LAC was examined by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was used for observing the effects of lentiviral vector-mediated MMP12 shRNA (shMMP12) on cell growth and invasion in LAC cell lines (A549), indicated by MTT and Transwell assays. We found that the expression of MMP12 protein was significantly increased in LAC tissues compared with that in adjacent non-cancerous tissues (ANCT) (57.69% vs. 32.69%, P = 0.019), and was closely correlated with the pathological stage and lymph node metastasis of LAC patients (P = 0.01; P = 0.003). Knockdown of MMP12 inhibited proliferation and invasion of LAC cells followed by the downregulation of proliferating cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF). In conclusion, our findings show that high expression of MMP12 is correlated with the pathological stage and tumor metastasis of LAC patients, and knockdown of MMP12 suppresses the development of LAC cells, suggesting that MMP12 may be a promising therapeutic target for the treatment of LAC.

The effects of nicotine administration on the pathophysiology of rat aortic wall

Abdominal aortic aneurysm (AAA) is the progressive dilation of the abdominal aorta. Nicotine is reported to be associated with the development and rupture of AAA, but the pathological effects of nicotine on normal rat aorta have not been determined. We investigated pathological changes in the aortic wall of rats caused by the administration of nicotine. Nicotine administration weakened the vascular wall, increased gelatinolytic activity and promoted the destruction of elastin and collagen in the rat abdominal aorta. There were no differences in the areas positive for matrix metalloproteinase (MMP)-2 and MMP-9 between the control and nicotine treated groups. The areas positive for MMP-12 in the nicotine group were significantly greater than for the control group. Gelatinolytic activity in the aortic wall was increased significantly in the nicotine group. Our findings suggest that MMP-12 is sensitive to nicotine exposure in rats.

Heterogeneous nuclear ribonucleoprotein K is associated with poor prognosis and regulates proliferation and apoptosis in bladder cancer

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an essential RNA- and DNA-binding protein that regulates diverse biological events, especially DNA transcription. hnRNPK overexpression is related to tumorigenesis in several cancers. However, both the expression patterns and biological mechanisms of hnRNPK in bladder cancer are unclear. We investigated hnRNPK expression by immunohistochemistry in 188 patients with bladder cancer, and found that hnRNPK expression levels were significantly increased in bladder cancer tissues and that high-hnRNPK expression was closely correlated with poor prognosis. Loss- and gain-of-function assays demonstrated that hnRNPK promoted proliferation, anti-apoptosis, and chemoresistance in bladder cancer cells in vitro, and hnRNPK knockdown suppressed tumorigenicity in vivo. Mechanistically, hnRNPK regulated various functions in bladder cancer by directly mediating cyclin D1, G0/G1 switch 2 (G0S2), XIAP-associated factor 1, and ERCC excision repair 4, endonuclease catalytic subunit (ERCC4) transcription. In conclusion, we discovered that hnRNPK plays an important role in bladder cancer, suggesting that it is a potential prognostic marker and a promising target for treating bladder cancer.

Serum MMP7, MMP10 and MMP12 level as negative prognostic markers in colon cancer patients

Background

Matrixmetalloproteinases (MMPs) comprise a family of zinc-dependent endopeptidases which are involved in angiogenesis, tumor invasion and metastatic formation. Up to date, the prognostic relevance of MMPs in serum of patients with colon cancer remains unknown. Thus, we wanted to assess an expression pattern of MMPs in a homogenous cohort of colon cancer patients to assess their potential as prognostic biomarkers.

Methods

Differences in the expression pattern of MMP7, MMP10 and MMP12 in 78 serum specimens of patients with an adenocarcinoma of the colon and serum specimens of a healthy control group were assessed using Luminex-100 technologies. Subsequently, we correlated these results with histopathological and clinical data of the patients.

Results

Luminex based expression analysis revealed a significant overexpression of MMP7 and an overexpression of MMP10 and MMP12 in the sera of colon cancer patients compared to the healthy control group. Patients with vascular invasion showed a significantly higher MMP12 expression than V0-staged patients. Moreover overexpression of MMP7, MMP10 and MMP12 in colon cancer patients´ sera displayed a significantly impaired overall survival. Multivariate analysis revealed high MMP10 serum levels to be an independent adverse prognostic marker in colon cancer patients.

Conclusions

Expression patterns of MMP7, MMP10 and MMP12 in colon cancer patients´ sera are different compared to serum specimens of healthy individuals. Furthermore, overexpression of MMP7, MMP10 and MMP12 in colon cancer patients´ sera correlates with a dismal prognosis and may help to stratify patients into different risk groups.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2515-7) contains supplementary material, which is available to authorized users.

Cytoplasmic Accumulation of Heterogeneous Nuclear Ribonucleoprotein K Strongly Promotes Tumor Invasion in Renal Cell Carcinoma Cells

Heterogeneous nuclear ribonucleoprotein (hnRNP) K is a part of the ribonucleoprotein complex which regulates diverse biological events. While overexpression of hnRNP K has been shown to be related to tumorigenesis in several cancers, both the expression patterns and biological mechanisms of hnRNP K in renal cell carcinoma (RCC) cells remain unclear. In this study, we showed that hnRNP K protein was strongly expressed in selected RCC cell lines (ACHN, A498, Caki-1, 786–0), and knock-down of hnRNP K expression by siRNA induced cell growth inhibition and apoptosis. Based on immunohistochemical (IHC) analysis of hnRNP K expression in human clear cell RCC specimens, we demonstrated that there was a significant positive correlation between hnRNP K staining score and tumor aggressiveness (e.g., Fuhrman grade, metastasis). Particularly, the rate of cytoplasmic localization of hnRNP K in primary RCC with distant metastasis was significantly higher than that in RCC without metastasis. Additionally, our results indicated that the cytoplasmic distribution of hnRNP K induced by TGF-β stimulus mainly contributed to TGF-β-triggered tumor cell invasion in RCC cells. Dominant cytoplasmic expression of ectopic hnRNP K markedly suppressed the inhibition of invasion by knock-down of endogenous hnRNP K. The expression level of matrix metalloproteinase protein-2 was decreased by endogenous hnRNP K knock-down, and restored by ectopic hnRNP K. Therefore, hnRNP K may be a key molecule involved in cell motility in RCC cells, and molecular mechanism associated with the subcellular localization of hnRNP K may be a novel target in the treatment of metastatic RCC.

Matrix metalloproteinase 13-containing exosomes promote nasopharyngeal carcinoma metastasis

Nasopharyngeal cancer (NPC) is an endemic type of head and neck cancer with a high rate of cervical lymph node metastasis. Metastasis is the major cause of death in NPC patients. Increasing evidence indicates that exosomes play a pivotal role in promoting cancer metastasis by enhancing angiogenesis and ECM degradation. Matrix metalloproteinase 13 is an important kind of matrix proteinase that is often overexpressed in various tumors and increases the risk of metastasis. However, little is known about the potential role of MMP13‐containing exosomes in NPC. In this study, we found that MMP13 was overexpressed in NPC cells and exosomes purified from conditioned medium (CM) as well as NPC patients’ plasma. Transwell analysis revealed that MMP13‐containing exosomes facilitated the metastasis of NPC cells. Furthermore, siRNA inhibited the effect of MMP13‐containing exosomes on tumor cells metastasis as well as angiogenesis. The current findings provided novel insight into the vital role of MMP13‐containing exosomes in NPC progression which might offer unique insights for potential therapeutic strategies for NPC progressions.

Association between MMP-12-82A/G polymorphism and cancer risk: a meta-analysis

BACKGROUND

Numerous studies have focused on the association between MMP-12-82A>G polymorphism and cancer risk, but produced inconsistent results. Therefore, we performed a meta-analysis of case-control study to evaluate the association of MMP-12-82A>G polymorphism and cancer risk.

METHODS

A systematic literature search was conducted among PubMed, Web of Science, Science Direct, China National Knowledge Infrastructure (CNKI) and Wangfang databases updated on May 1st, 2015. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the strength of association between this polymorphism and cancer risk.

RESULTS

A total of seventeen case-control studies with 7,450 cases and 7,348 controls were identified and analyzed. Overall, there was no statistically significant association between MMP-12-82A>G polymorphism and increased risk of cancer under all genetic models. Subgroup analysis by ethnicity observed that there is no strong relationship between MMP-12-82A>G polymorphism and cancer risk among Asian and European populations. Furthermore, stratified analysis based on the source of control revealed no statistically significant association between MMP-12-82A>G polymorphism and cancer risk either in hospital-based or population-based studies. However, when we stratified analysis based on cancer type, significant association was found in ovarian cancer, but not in other types of cancer.

CONCLUSION

This meta-analysis suggests that MMP-12-82A>G polymorphism is not significantly associated with overall cancer risk. However, MMP-12-82A>G polymorphism may increase the susceptibility to ovarian cancer.

Matrix Metalloproteinase 14 Overexpression Is Correlated with the Progression and Poor Prognosis of Nasopharyngeal Carcinoma

BACKGROUND AND AIMS

Matrix metalloproteinase 14 (MMP14) has been identified to play a significant role in several types of cancers, but little is known about the significance of MMP14 in nasopharyngeal carcinoma (NPC) patients. The aim of this study was to explore the association of MMP14 expression with clinicopathologic features and prognosis in NPC.

METHODS

MMP14 mRNA and protein expressions were examined in NPC and nasopharyngeal tissues through real-time PCR and immunohistochemistry. Meanwhile, the relationship of MMP14 expression levels with clinical features and prognosis of NPC patients was analyzed.

RESULTS

MMP14 mRNA expression was markedly higher in NPC tissues than in nasopharyngeal epithelium tissues (p = 0.002). Using immunohistochemistry, staining for MMP14 protein was found in the normal nasopharyngeal epithelial cells and malignant epithelial cells, but increased expression of MMP14 was observed in NPC samples compared with normal nasopharyngeal epithelium samples (p = 0.027). In addition, high levels of MMP14 protein were positively correlated with the status of clinical stage (p = 0.009), N classification (p = 0.006), and distant metastasis (p = 0.005) of NPC patients. Patients with higher MMP14 expression had a significantly shorter overall survival time than did patients with low MMP14 expression. Multivariate analysis indicated that the level of MMP14 expression was an independent prognostic indicator (p < 0.001) for the survival of patients with NPC.

CONCLUSIONS

MMP14 overexpression is a potentially unfavorable prognostic factor for NPC patients.

Dinitrosopiperazine-mediated phosphorylated-proteins are involved in nasopharyngeal carcinoma metastasis

N,N'-dinitrosopiperazine (DNP) with organ specificity for nasopharyngeal epithelium, is involved in nasopharyngeal carcinoma (NPC) metastasis, though its mechanism is unclear. To reveal the pathogenesis of DNP-induced metastasis, immunoprecipitation was used to identify DNP-mediated phosphoproteins. DNP-mediated NPC cell line (6-10B) motility and invasion was confirmed. Twenty-six phosphoproteins were increased at least 1.5-fold following DNP exposure. Changes in the expression levels of selected phosphoproteins were verified by Western-blotting analysis. DNP treatment altered the phosphorylation of ezrin (threonine 567), vimentin (serine 55), stathmin (serine 25) and STAT3 (serine 727). Furthermore, it was shown that DNP-dependent metastasis is mediated in part through ezrin at threonine 567, as DNP-mediated metastasis was decreased when threonine 567 of ezrin was mutated. Strikingly, NPC metastatic tumors exhibited a higher expression of phosphorylated-ezrin at threonine 567 than the primary tumors. These findings provide novel insight into DNP-induced NPC metastasis and may contribute to a better understanding of the metastatic mechanisms of NPC tumors.