Genetic variations in the PI3K-PTEN-AKT-mTOR pathway are associated with distant metastasis in nasopharyngeal carcinoma patients treated with intensity-modulated radiation therapy

Predicting Bone Metastasis Risk Based on Skull Base Invasion in Locally Advanced Nasopharyngeal Carcinoma

Objective

To develop and validate a bone metastasis prediction model based on skull base invasion (SBI) in patients with locally advanced nasopharyngeal carcinoma (LA-NPC).

Methods

This retrospective cohort study enrolled 290 patients with LA-NPC who received intensity-modulated radiation therapy in two hospitals from 2010 to 2020. Patient characteristics were grouped by SBI and hospital. Both unadjusted and multivariate-adjusted models were used to determine bone metastasis risk based on SBI status. Subgroup analysis was performed to investigate heterogeneity using a forest graph. Cox proportional hazard regression analysis was used to screen for risk factors of bone metastasis-free survival (BMFS). A nomogram of BMFS based on SBI was developed and validated using C-index, receiver operating characteristic curve, calibration curves, and decision curve analysis after Cox proportional hazard regression analysis.

Results

The incidence of bone metastasis was 14.83% (43/290), 20.69% (24/116), and 10.92% (19/174) in the overall population, SBI-positive group, and SBI-negative group, respectively. In the unadjusted model, SBI was associated with reduced BMFS [HR 2.43 (1.32–4.47), P = 0.004], and the results remained stable after three continuous adjustments (P <0.05). No significant interaction was found in the subgroup analyses (P for interaction >0.05). According to Cox proportional hazard regression analysis and clinical value results, potential risk factors included SBI, Karnofsky performance status, TNM stage, induction chemotherapy, concurrent chemoradiotherapy, and adjuvant chemotherapy. Using a training C-index of 0.80 and a validation C-index of 0.79, the nomogram predicted BMFS and demonstrated satisfactory prognostic capability in 2, 3, and 5 years (area under curve: 83.7% vs. 79.6%, 81.7% vs. 88.2%, and 79.0% vs. 93.8%, respectively).

Conclusion

Skull base invasion is a risk factor for bone metastasis in patients with LA-NPC. The SBI-based nomogram model can be used to predict bone metastasis and may assist in identifying LA-NPC patients at the highest risk of bone metastasis.

Risk-Related Genes and Associated Signaling Pathways of Gastrointestinal Stromal Tumors

Purpose

Knowledge on the potential association between differential gene expression and risk of gastrointestinal stromal tumors (GISTs) is currently limited. We used bioinformatics tools to identify differentially expressed genes in GIST samples and the related signaling pathways of these genes.

Patients and Methods

The GSE136755 dataset was obtained from the GEO database and differentially expressed genes (CENPA, CDK1, TPX2, CCNB1, CCNA2, BUB1, AURKA, KIF11, NDC80) were screened using String and Cytoscape bioinformatics tools. Then, three groups of eight patients at high, intermediate and low risk of GIST were selected from patients diagnosed with GIST by immunohistochemistry in our hospital from October 2020 to March 2021. Differential expression of CDK1 and BUB1 was verified by comparing the amount of expressed p21-Activated kinase 4 (PAK4) protein in pathological sections.

Results

SPSS26.0 analysis showed that the expression level of PAK4 in GISTs was significantly higher than in normal tissues and paratumoral tissues and there was significant difference among the three groups of patients (P < 0.01). PAK4 levels in paratumoral and normal tissues were negligible with no significant difference between the tissues.

Conclusion

CENPA, CDK1, TPX2, CCNB1, CCNA2, BUB1, AURKA, KIF11 and NDC80 gene expression can be used as biomarkers to assess the risk of gastrointestinal stromal tumors whereby expression increases gradually with the increased risk of GIST formation. The genes encode proteins that regulate the division, proliferation and apoptosis of gastrointestinal stromal tumors mainly through PI3K/AKT, MARK, P53, WNT and other signaling pathways.

The Relevance of Regenerating Gene 1a Polymorphisms to Radiation Sensitivity and Survival of Nasopharyngeal Carcinoma Receiving Radiotherapy in a Southern Chinese Population

Objective

Gene polymorphism is closely related to tumor development, therapeutic response and prognosis. The relationship between regenerating gene 1A (Reg1A) polymorphism and nasopharyngeal carcinoma (NPC) is unclear. This retrospective study aimed to analyze the association between Reg1a polymorphisms and metastasis, radiation sensitivity and survivals in patients with NPC.

Methods

A total of 308 patients who had received radiotherapy at the Affiliated Xinhua Hospital, Hainan Medical College, between January 2010 and December 2018 with NPC, were enrolled for assessment of Reg1a polymorphisms through direct DNA sequencing.

Results

In the polymorphism of gene REG1A, patients with rs10165462 20CC genotype had later T stages (OR = 4.051, 95% CI: 1.775–9.244, P = 0.001), whereas carriers with rs12072 2922CC genotype had earlier T stages (OR = 1.891, 95% CI: 1.018–3.514, P = 0.044) after adjustments for age and gender, respectively. Among rs10165462 20 C/T polymorphism, 20TT wild-type was associated with better radiation response (P = 0.0019), and multivariate analysis showed that it was the only genotype of polymorphism that was significantly associated with better radiation response (OR = 0.265, 95% CI: 0.096–0.727, P = 0.01). Patients with the 20TT wild-type had a better five-year overall survival (60.9%) rate and five-year progression-free survival (60.8%) than those with the 20CC genotype (41.8% and 39.4%, P = 0.01 and P = 0.004, respectively). Patients with variant alleles (CC + CT) had significantly poorer OS (45.2%) and PFS (41.8%) compared with wild-type (TT) carriers (60.9% and 60.8%; P = 0.037 and P = 0.015, respectively). As for rs12072, patients with variant alleles (TT + TC) had significantly adverse OS and PFS compared with wild-type (CC) carriers (62.5% vs 44.8% and 62.5% vs 42.9%; P = 0.024 and P = 0.027, respectively). Cox regression showed that rs10165462 20CT was the only prognostic factor for OS (HR = 1.642, 95% CI 1.038–2.598, P = 0.034) and PFS (HR = 1.705, 95% CI 1.080–2.692, P = 0.022).

Conclusion

Reg1a polymorphisms may be a predictor of radiation response, local invasion, OS and PFS in patients with NPC who undergo radiotherapy treatment.

Correlation of the AKT/mTOR signaling pathway with the clinicopathological features and prognosis of nasopharyngeal carcinoma

The primary aim of this study was to examine the correlation of the AKT/mTOR signaling pathway with the clinicopathological features and prognostic significance in nasopharyngeal carcinoma (NPC). The study tissues were collected from 285 patients with NPC and normal mucosal tissues were obtained from 289 individuals with normal nasopharynxes. Immunohistochemical staining was used to detected the expression of the AKT, mTOR, and p70 ribosomal S6 kinase (P70S6K) proteins. Follow-up was performed for between 8 and 60 months. Spearman’s rank correlation analysis was performed to evaluate the correlation of the expression of the AKT, mTOR, and P70S6K proteins in NPC tissues. Kaplan-Meier curves were plotted to show the survival of patients with NPC. A Cox proportional hazards model was used to explore the independent risk factors for prognosis. The expression of the AKT, mTOR, and P70S6K proteins in NPC tissues was higher than that in healthy nasopharyngeal mucosal tissues, and was correlated with T-staging, N-staging, clinical stage, distant metastasis, and differentiation. The positive expression of the AKT, mTOR, and P70S6K proteins was higher in patients with stage III/IV NPC, low differentiation, and metastasis. The survival rates of patients with NPC with AKT-positive, mTOR-positive, and P70S6K-positive expression were considerably lower than those without the expression of these proteins. Distant metastasis and the overexpression of the AKT, mTOR, and P70S6K proteins were independent risk factors for the prognosis of patients with NPC. The results obtained from this study indicated an association between the AKT/mTOR signaling pathway and the progression of NPC. The upregulation of the AKT/mTOR pathway in patients with NPC is a predictor of poor prognosis.

Influences of S100A8 and S100A9 on Proliferation of Nasopharyngeal Carcinoma Cells through PI3K/Akt Signaling Pathway

Objective

To investigate the effects of S100A8 and S100A9 on proliferation in nasopharyngeal carcinoma cells and the regulatory effects of PI3K/Akt signaling pathway.

Methods

Nasopharyngeal carcinoma cells (CNE1) were cultured and randomly divided into three groups: control group, S100A8/S100A9 overexpression group, and siRNA S100A8/S100A9 group. CCK-8 method was used to detect the effect of S100A8 and S100A9 on the viability of nasopharyngeal carcinoma cells. The effects of S100A8 and S100A9 on the colony forming ability of nasopharyngeal carcinoma cells were detected by colony forming assay. The effects of S100A8 and S100A9 on the proliferation of nasopharyngeal carcinoma cells were detected by EdU staining. The mRNA levels of PI3K and Akt were detected by RT-PCR. The expression levels of PI3K and Akt in NPC cells were detected by Western blot. Wortmannin, an inhibitor of PI3K/Akt pathway, was used to inhibit the activation of PI3K/Akt pathway.

Results

Compared with the control group, the cell viability, the number of plate clones, the positive rate of EdU staining, and the mRNA and protein levels of PI3K and Akt were increased in the overexpression group. Compared with the control group, the cell viability, the number of plate clones, the positive rate of EdU staining, and the mRNA and protein levels of PI3K and Akt were decreased in the siRNA group. After inhibiting the activation of PI3K/Akt pathway, the viability of NPC cells in the overexpression group decreased significantly at 48 h and 72 h, while that in the siRNA group increased significantly.

Conclusion

SiRNA S100A8 and S100A9 could inhibit the proliferation of nasopharyngeal carcinoma cells, and the underlying mechanism may be related to the inhibition of PI3K/Akt signaling pathway.

Oxidative Stress-Induced Unscheduled CDK1-Cyclin B1 Activity Impairs ER-Mitochondria-Mediated Bioenergetic Metabolism

Targeting the activities of endoplasmic reticulum (ER)-mitochondrial-dependent metabolic reprogramming is considered one of the most promising strategies for cancer treatment. Here, we present biochemical subcellular fractionation, coimmunoprecipitation, gene manipulation, and pharmacologic evidence that induction of mitochondria-localized phospho (p)-cyclin dependent kinase 1 (CDK1) (Thr 161)-cyclin B1 complexes by apigenin in nasopharyngeal carcinoma (NPC) cells impairs the ER-mitochondrial bioenergetics and redox regulation of calcium (Ca⁺⁺) homeostasis through suppressing the B cell lymphoma 2 (BCL-2)/BCL-2/B-cell lymphoma-extra large (BCL-x_L)-modulated anti-apoptotic and metabolic functions. Using a specific inducer, inhibitor, or short hairpin RNA for acid sphingomyelinase (ASM) demonstrated that enhanced lipid raft-associated ASM activity confers alteration of the lipid composition of lipid raft membranes, which leads to perturbation of protein trafficking, and induces formation of p110α free p85α-unphosphorylated phosphatase and tensin homolog deleted from chromosome 10 complexes in the lipid raft membranes, causing disruption of phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt)-GTP-ras-related C3 botulinum toxin substrate 1 (Rac1)-mediated signaling, thus triggering the p-CDK1 (Thr 161))-cyclin B1-mediated BCL-2 (Thr 69/Ser 87)/BCL-x_L (Ser 62) phosphorylation and accompanying impairment of ER-mitochondria-regulated bioenergetic, redox, and Ca⁺⁺ homeostasis. Inhibition of apigenin-induced reactive oxygen species (ROS) generation by a ROS scavenger N-acetyl-L-cysteine blocked the lipid raft membrane localization and activation of ASM and formation of ceramide-enriched lipid raft membranes, returned PI3K-Akt-GTP-Rac1-modulated CDK1-cyclin B1 activity, and subsequently restored the BCL-2/BCL-x_L-regulated ER-mitochondrial bioenergetic activity. Thus, this study reveals a novel molecular mechanism of the pro-apoptotic activity of ASM controlled by oxidative stress to modulate the ER-mitochondrial bioenergetic metabolism, as well as suggests the disruption of CDK1-cyclin B1-mediated BCL-2/BCL-x_L oncogenic activity&nbsp;by triggering oxidative stress-ASM-induced PI3K-Akt-GTP-Rac1 inactivation as a therapeutic approach for NPC.

ER resident protein 44 promotes malignant phenotype in nasopharyngeal carcinoma through the interaction with ATP citrate lyase

Background

Nasopharyngeal carcinoma (NPC) is one of the most common malignancy in head and neck. With the development of treatments, the prognosis has improved these years, but metastasis is still the main cause of treatment failure. The endoplasmic reticulum (ER) resident protein 44 is a UPR-induced ER protein of the protein disulphide isomerase (PDI) family. This study investigated the role of ERp44 in NPC progression.

Methods

Firstly, immunohistochemistry, western blot and qRT-PCR were used to investigate the expression of ERp44 in NPC samples and cell lines. We analyzed 44 NPC samples for ERp44 expression and investigated the association between its expression level with clinicopathologic parameters. Then we took CCK8, Transwell migration assay and used the zebrafish model to access the role of ERp44 on the malignant phenotype in NPC cells. Secondly, we used co-IP to gain the proteins that interact with ERp44 and took proteomic analysis. Furthermore, we successfully constructed the mutant variants of ERp44 and found the interaction domain with ATP citrate lyase(ACLY). Lastly, we subcutaneously injected NPC cells into nude mice and took immunohistochemistry to exam the expression of ACLY and ERp44. Then we used western blot to detect the expression level of epithelial-mesenchymal transition (EMT) markers.

Results

In the present study, we found ERp44 was elevated in NPC tissues and correlated with clinical stages and survive state of the patients. In vitro, the downregulation of ERp44 in NPC cells (CNE2, 5-8F) could suppress cells proliferation and migration. After that, we recognized that ACLY might be a potential target that could interact with ERp44. We further constructed the mutant variants of ERp44 and found the interaction domain with ACLY. The promotion of ERp44 on cell migration could be inhibited when ACLY was knocked down. More importantly, we also observed that the interaction of ERp44 with ACLY, especially the thioredoxin region in ERp44 play a vital role in regulating EMT. Lastly, we found ERp44 was positively correlated with the expression of ACLY and could promote NPC cells growth in nude mice.

Conclusion

Our data indicated that ERp44 participates in promoting NPC progression through the interaction with ACLY and regulation of EMT.

Targeting the signaling in Epstein-Barr virus-associated diseases: mechanism, regulation, and clinical study

Epstein–Barr virus-associated diseases are important global health concerns. As a group I carcinogen, EBV accounts for 1.5% of human malignances, including both epithelial- and lymphatic-originated tumors. Moreover, EBV plays an etiological and pathogenic role in a number of non-neoplastic diseases, and is even involved in multiple autoimmune diseases (SADs). In this review, we summarize and discuss some recent exciting discoveries in EBV research area, which including DNA methylation alterations, metabolic reprogramming, the changes of mitochondria and ubiquitin-proteasome system (UPS), oxidative stress and EBV lytic reactivation, variations in non-coding RNA (ncRNA), radiochemotherapy and immunotherapy. Understanding and learning from this advancement will further confirm the far-reaching and future value of therapeutic strategies in EBV-associated diseases.

Akt1 genetic variants confer increased susceptibility to thyroid cancer

The PI3K-Akt-mTOR pathway plays a central role in the development of non-medullary thyroid carcinoma (NMTC). Although somatic mutations have been identified in these genes in NMTC patients, the role of germline variants has not been investigated. Here, we selected frequently occurring genetic variants in AKT1, AKT2, AKT3, PIK3CA and MTOR and have assessed their effect on NMTC susceptibility, progression and clinical outcome in a Dutch discovery cohort (154 patients, 188 controls) and a Romanian validation cohort (159 patients, 260 controls). Significant associations with NMTC susceptibility were observed for AKT1 polymorphisms rs3803304, rs2494732 and rs2498804 in the Dutch discovery cohort, of which the AKT1 rs3803304 association was confirmed in the Romanian validation cohort. No associations were observed between PI3K-Akt-mTOR polymorphisms and clinical parameters including histology, TNM staging, treatment response and clinical outcome. Functionally, cells bearing the associated AKT1 rs3803304 risk allele exhibit increased levels of phosphorylated Akt protein, potentially leading to elevated signaling activity of the oncogenic Akt pathway. All together, germline encoded polymorphisms in the PI3K-Akt-mTOR pathway could represent important risk factors in development of NMTC.

PNCK depletion inhibits proliferation and induces apoptosis of human nasopharyngeal carcinoma cells in vitro and in vivo

Purpose: Recent studies indicate that pregnancy upregulated non-ubiquitous calmodulin kinase (PNCK) is significantly up-regulated in breast and renal carcinomas. However, the expression profile and its biological relevance of PNCK in nasopharyngeal carcinoma (NPC) have not been elucidated.

Methods: The expression level of PNCK was detected in specimens of NPC (n=10) and normal tissues (n=10) by real-time PCR and immunohistochemistry. Celigo Cell Counting and MTT assay were used to measure cell viability. Apoptosis was detected by flow cytometric analysis and caspases 3/7 activity assay. Real-time PCR and Western blotting were performed to evaluate the expression of PNCK. The bioluminescence imaging was used to evaluate the effects of PNCK knockdown on tumor growth using a xenograft animal model. The global gene expression profile was determined in wild type and PNCK-depleted CNE-2 cells via transcriptomics analysis. For mechanical investigation, the changes of PI3K/AKT/mTOR signaling pathway were detected by Western blotting.

Results: The mRNA and protein levels of PNCK were increased in human NPC samples. In vitro experiments showed that shRNA or CRISPR-Cas9 mediated silencing of PNCK inhibited proliferation and induced apoptosis in NPC cells. In addition, in vivo assay revealed that knockdown of PNCK suppressed tumor growth. Consistently, a significant reduction of tumor bioluminescence in mice inoculated with PNCK-knockdown cells compared to that of control cells. In gene expression, the transcriptomics analysis revealed that there were 589 upregulated genes and 589 downregulated genes in PNCK-knockdown cells. Ingenuity Pathway Analysis (IPA) identified significant changes of PI3K/AKT/mTOR signaling pathway in PNCK-knockdown cells. Furthermore, western blot analysis revealed that interference with PNCK reduced the phosphorylation levels of PI3K, AKT and mTOR in CNE-2 cells.

Conclusion: This study for the first time demonstrates that knockdown of PNCK could suppress growth and induce apoptosis of NPC cells both in vitro and in vivo by regulating PI3K/AKT/mTOR signaling pathway. These findings suggest that PNCK might be a novel therapeutic target for NPC treatment.

Driver gene alterations and activated signaling pathways toward malignant progression of gastrointestinal stromal tumors

Mutually exclusive KIT and PDGFRA mutations are considered to be the earliest events in gastrointestinal stromal tumors (GIST), but insufficient for their malignant progression. Herein, we aimed to identify driver genes and signaling pathways relevant to GIST progression. We investigated genetic profiles of 707 driver genes, including mutations, gene fusions, copy number gain or loss, and gene expression for 65 clinical specimens of surgically dissected GIST, consisting of six metastatic tumors and 59 primary tumors from stomach, small intestine, rectum, and esophagus. Genetic alterations included oncogenic mutations and amplification‐dependent expression enhancement for oncogenes (OG), and loss of heterozygosity (LOH) and expression reduction for tumor suppressor genes (TSG). We assigned activated OG and inactivated TSG to 27 signaling pathways, the activation of which was compared between malignant GIST (metastasis and high‐risk GIST) and less malignant GIST (low‐ and very low‐risk GIST). Integrative molecular profiling indicated that a greater incidence of genetic alterations of driver genes was detected in malignant GIST (96%, 22 of 23) than in less malignant GIST (73%, 24 of 33). Malignant GIST samples groups showed mutations, LOH, and aberrant expression dominantly in driver genes associated with signaling pathways of PI3K (PIK3CA, AKT1, and PTEN) and the cell cycle (RB1, CDK4, and CDKN1B). Additionally, we identified potential PI3K‐related genes, the expression of which was upregulated (SNAI1 and TPX2) or downregulated (BANK1) in malignant GIST. Based on our observations, we propose that inhibition of PI3K pathway signals might potentially be an effective therapeutic strategy against malignant progression of GIST.

Systemic immune-inflammation index as a prognostic marker in patients with newly diagnosed metastatic nasopharyngeal carcinoma: a propensity score-matched study

Background

Systemic immune-inflammation index (SII) is significantly associated with poor survival in variety of cancers. However, SII has not yet been investigated in patients with newly diagnosed metastatic nasopharyngeal carcinoma (mNPC). Thus, our aim is to explore the role of SII in metastatic Nasopharyngeal Carcinoma.

Methods

Two hundred and forty-three patients with newly diagnosed mNPC were retrospectively enrolled. The Kaplan-Meier analysis and Cox regression analysis was performed to evaluate the prognostic value of SII in overall survival (OS) and progression-free survival (PFS). Heterogeneity of factors was balanced by using propensity score-matched (PSM) analysis (1:1 for high SII versus low SII).

Results

Kaplan-Meier analysis showed that patients with high SII were associated with poor median OS (18.0 vs. 36.0 m, P<0.001) and PFS (10.0 vs. 22.0 m, P<0.001) in mNPC. The Cox regression analysis suggested that high SII was a prognostic factor for OS (HR 1.75, 95% CI: 1.22–2.52, P=0.001) and PFS (HR 1.69, 95% CI: 1.22–2.35, P=0.002). PSM analysis still confirmed that SII was an independent marker for OS (HR 1.86, 95% CI: 1.22–2.83, P=0.004) and PFS (HR 1.84, 95% CI: 1.23–2.77, P=0.003).

Conclusions

SII is an independent prognostic biomarker for poor OS and PFS in patients with newly diagnosed mNPC and might be a promising tool for guiding treatment strategy decisions.

Combining CDKN1A gene expression and genome-wide SNPs in a twin cohort to gain insight into the heritability of individual radiosensitivity

Individual variability in response to radiation exposure is recognised and has often been reported as important in treatment planning. Despite many efforts to identify biomarkers allowing the identification of radiation sensitive patients, it is not yet possible to distinguish them with certainty before the beginning of the radiotherapy treatment. A comprehensive analysis of genome-wide single-nucleotide polymorphisms (SNPs) and a transcriptional response to ionising radiation exposure in twins have the potential to identify such an individual. In the present work, we investigated SNP profile and CDKN1A gene expression in blood T lymphocytes from 130 healthy Caucasians with a complex level of individual kinship (unrelated, mono- or dizygotic twins). It was found that genetic variation accounts for 66% (95% CI 37-82%) of CDKN1A transcriptional response to radiation exposure. We developed a novel integrative multi-kinship strategy allowing investigating the role of genome-wide polymorphisms in transcriptomic radiation response, and it revealed that rs205543 (ETV6 gene), rs2287505 and rs1263612 (KLF7 gene) are significantly associated with CDKN1A expression level. The functional analysis revealed that rs6974232 (RPA3 gene), involved in mismatch repair (p value = 9.68e-04) as well as in RNA repair (p value = 1.4e-03) might have an important role in that process. Two missense polymorphisms with possible deleterious effect in humans were identified: rs1133833 (AKIP1 gene) and rs17362588 (CCDC141 gene). In summary, the data presented here support the validity of this novel integrative data analysis strategy to provide insights into the identification of SNPs potentially influencing radiation sensitivity. Further investigations in radiation response research at the genomic level should be therefore continued to confirm these findings.

MicroRNA-506 inhibits tumor growth and metastasis in nasopharyngeal carcinoma through the inactivation of the Wnt/β-catenin signaling pathway by down-regulating LHX2

Background

Epithelial-mesenchymal transition (EMT)-associated proteins play key roles in cancer progression and metastasis with the involvement of microRNAs (miRNAs). This study aims to assess the role of miR-506 working in tandem with LIM Homeobox 2 (LHX2) in EMT and metastasis through the Wnt/β-catenin signaling pathway in nasopharyngeal carcinoma (NPC).

Methods

Differentially expressed genes associated with NPC were screened using microarray analyses, from which LHX2 was identified. Next, the potential relationship between miR-506 and LHX2 was analyzed. In order to explore the effect of miR-506 or LHX2 on NPC cell proliferation, migration, invasion and apoptosis, serials of mimics, inhibitors or siRNA against LHX2 were transfected into NPC cells. Then, the expression patterns of LHX2, Wnt1, β-catenin, E-cadherin, Vimentin, TCF4 and Twist were determined to assess the influence of miR-506 or LHX2 on EMT as well as the relationship between the Wnt/β-catenin signaling pathway and TCF4. The tumorigenicity and lymph node metastasis (LNM) in xenograft tumors of nude mice were observed.

Results

The has-miR-506-3p was identified as the down-regulated gene in NPC based on the microarray data while LHX2 was negatively regulated by miR-506. Over-expression of miR-506 or silencing of LHK2 inhibited NPC cell proliferation, migration, invasion, tumorigenicity and LNM but promoted apoptosis indicated by decreased Wnt1, β-catenin, Vimentin, TCF4 and Twist expressions along with increased E-cadherin expressions.

Conclusions

miR-506 inhibits tumor growth and metastasis in NPC via inhibition of Wnt/β-catenin signaling by down-regulating LHX2, accompanied by decreased TCF4. Taken together, miR-506 targeted-inhibition LHX2 presents a promising therapeutic strategy for the treatment of NPC.

Trial registration

ChiCTR1800018889. Registered 15 October 2018.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1023-4) contains supplementary material, which is available to authorized users.

PI3K-PKB-mTOR hyperactivation in relation to nasopharyngeal carcinoma progression and prognosis

Nasopharyngeal carcinoma (NPC) has a unique and complex etiology, which is not completely understood. The aim of this study is to investigate the expression patterns of phosphatidylinositol 3-kinase (PI3K), protein kinase B (PKB), and mammalian target of rapamycin (mTOR) proteins in patients with NPC and their relationship with NPC progression and prognosis. Between January 2008 and March 2010, PI3K, PKB, and mTOR protein expressions were detected using immunohistochemistry among 119 patients with NPC and 30 healthy people. A 5-year follow-up was conducted for all patients. Correlations of PI3K, PKB, and mTOR proteins with the clinicopathological features and prognosis of NPC were evaluated using Spearman's rank correlation coefficient and Kaplan-Meier curve. Cox's regression analysis was performed to analyze the risk factors for the prognosis of NPC. First, PI3K, PKB, and mTOR were highly expressed in patients with NPC. The expressions of PI3K, PKB, and mTOR proteins were associated with T stage, N stage, clinical stage, relapse, and distant metastasis. Meanwhile, PI3K is positively correlated with PKB and PKB is positively correlated with mTOR in NPC. Higher PI3K, PKB, and mTOR protein expressions were related to a shorter survival time and a lower survival rate in NPC. Cox regression analysis revealed that age, T stage, N stage, PI3K, PKB, and mTOR were independent risk factors for NPC patient survival. Altogether, our data suggest that overexpression of PI3K, PKB, and mTOR proteins is an important indicator of poor survival in NPC. In addition, inhibition of PI3K-PKB-mTOR signaling may also contribute to the development of new therapeutic strategies for NPC.

RPA1 downregulation enhances nasopharyngeal cancer radiosensitivity via blocking RAD51 to the DNA damage site

BACKGROUND/AIM

Nasopharyngeal cancer (NPC) has a high local recurrence rate due to its resistance to ionizing radiation (IR). Replication protein A1 (RPA1) is one of the main elements in the homologous repair (HR) pathway, which is closely associated with the repair of DNA double strand breaks (DDBs). Studies on the relationship between RPA1 and the radiosensitivity of NPC are substantially limited. It was hypothesized that RPA1 plays a crucial role in predicting the radiosensitivity of NPC.

METHODS

The protein expression of RPA1 in 182 patients with NPC in the complete response (CR) and non-complete response (nCR) groups was evaluated using immunohistochemistry. Then, univariate and multivariate analysis were performed using SPSS software vision 22 to determine the relationship between the expression of RPA1 and the clinicopathological features. In addition, the mRNA expression of RPA1 was tested in 24 fresh samples using qRT-PCR. RPA1 was silenced in CNE-2R cell lines combined with IR to measure the radiosensitivity, proliferation, DNA damage repair and cell cycle of CNE-2R cells. Xenograft models in nude mice were used to determine the effect of RPA1 on tumor growth after IR. Immunoblotting and immunofluorescence staining were performed to identify proteins that interacted with RPA1. All statistical tests were two-sided.

RESULTS

RPA1 protein was overexpressed in NPC patients with nCR (65.31%), and was an independent predictor of radiosensitivity (HR: 3.755, 95% CI: 1.990-7.085), in addition to Epstein-Barr virus (EBV; HR: 3.984; 95% CI: 1.524-10.410). The silencing of RPA1 increased the radiosensitivity of CNE-2R cells, blocked the repair of DNA, impaired cell proliferation, and contributed to G2/M cell cycle arrest. Furthermore, the xenograft models in nude mice revealed that silencing RPA1 combined with irradiation significantly retarded the growth of tumors. Moreover, the knockdown of RPA1 decreased Rad51 collection to the damage site and prolonged the time of DNA repair.

CONCLUSION

RPA1 protein is frequently overexpressed in NPC patients with nCR. The silencing of RPA1 enhanced the radiosensitivity of CNE-2R cells. These present findings reveal that RPA1 is a potential biomarker for predicting the radiosensitivity in NPC.

BMP2 promotes proliferation and invasion of nasopharyngeal carcinoma cells via mTORC1 pathway

Bone morphogenetic protein-2 (BMP2) is a secreted protein that highly expressed in a variety of cancers and contributes to cell proliferation, migration, invasiveness, mobility, metastasis and EMT. However, its clinical significance and biological function in nasopharyngeal carcinoma (NPC) remain unknown up to now. Up-regulation of BMP2 was first observed in NPC cell lines by a genome-wide transcriptome analysis in our previous study. In this study, BMP2 mRNA was detected by qRT-PCR and data showed that it was upregulated in NPC compared with non-cancerous nasopharynx samples. Immunohistochemistry (IHC) analysis in NPC specimens revealed that high BMP2 expression was significantly associated with clinical stage, distant metastasis and shorter survival of NPC patients. Moreover, overexpression of BMP2 in NPC cells promoted cell proliferation, migration, invasiveness and epithelial-mesenchymal transition (EMT). Mechanistically, BMP2 overexpression increase phosphorylated protein level of mTOR, S6K and 4EBP1. Correspondingly, mTORC1 inhibitor rapamycin blocked the effect of BMP2 on NPC cell proliferation and invasion. In conclusion, our results suggest that BMP2 overexpression in NPC enhances proliferation, invasion and EMT of tumor cells through the mTORC1 signaling pathway.

Knockdown of TMPRSS3, a Transmembrane Serine Protease, Inhibits Proliferation, Migration, and Invasion in Human Nasopharyngeal Carcinoma Cells

TMPRSS3 belongs to the large type II transmembrane serine protease (TTSP) family, which plays an important role in the development and progression of tumors. However, the function of TMPRSS3 in nasopharyngeal carcinoma (NPC) remains unclear. The present study aimed to examine the impact of TMPRSS3 on the proliferation, migration, and invasion of NPC cells and their potential mechanisms. Our results demonstrated that the expression of TMPRSS3 was obviously upregulated in human NPC tissues and cell lines. Knockdown of TMPRSS3 expression significantly suppressed the proliferation and tumorigenicity of NPC cells in vitro and in vivo. Furthermore, knockdown of TMPRSS3 inhibited migration and invasion, as well as prevented the EMT process in NPC cells. Finally, knockdown of TMPRSS3 attenuated activation of the PI3K/Akt signaling pathway in NPC cells. Taken together, the present study demonstrates that the knockdown of TMPRSS3 inhibits proliferation, migration, and invasion in human NPC cells through the inactivation of the PI3K/Akt signaling pathway. This study suggests that TMPRSS3 may be a potential therapeutic target for the treatment of NPC.