Reversal of taxol resistance by cisplatin in nasopharyngeal carcinoma by upregulating thromspondin-1 expression

Thrombospondin-1 in drug activity and tumor response to therapies

Thrombospondins (TSPs) have numerous different roles in cancer, regulating the behavior of cancer cells and non-neoplastic cells, and defining the responses of tumor cells to environmental changes, thorough their ability to orchestrate cellular and molecular interactions in the tumor microenvironment (TME). As a result of these activities, TSPs can also control drug delivery and activity, tumor response and resistance to therapies, with different outcomes depending on the nature of TSP-interacting cell types, receptors, and ligands, in a highly context-dependent manner. This review, focusing primarily on TSP-1, discusses the effects of TSPs on tumor response to chemotherapy, antiangiogenic, low-dose metronomic chemotherapy, immunotherapy, and radiotherapy, by analyzing TSP activity on different cell compartments - tumor cells, vascular endothelial cells and immune cells. We review evidence of the value of TSPs, specifically TSP-1 and TSP-2, as biomarkers of prognosis and tumor response to therapy. Finally, we examine possible approaches to develop TSP-based compounds as therapeutic tools to potentiate the efficacy of anticancer therapy.

A three-dimensional spheroid-specific role for Wnt-β-catenin and Eph-ephrin signaling in nasopharyngeal carcinoma cells

One of the greatest unmet needs hindering the successful treatment of nasopharyngeal carcinomas (NPCs) is for representative physiological and cost-effective models. Although Epstein-Barr virus (EBV) infection is consistently present in NPCs, most studies have focused on EBV-negative NPCs. For the first time, we established and analyzed three-dimensional (3D) spheroid models of EBV-positive and EBV-negative NPC cells and compared these to classical two-dimensional (2D) cultures in various aspects of tumor phenotype and drug responses. Compared to 2D monolayers, the 3D spheroids showed significant increases in migration capacity, stemness characteristics, hypoxia and drug resistance. Co-culture with endothelial cells, which mimics essential interactions in the tumor microenvironment, effectively enhanced spheroid dissemination. Furthermore, RNA sequencing revealed significant changes at the transcriptional level in 3D spheroids compared to expression in 2D monolayers. In particular, we identified known (VEGF, AKT and mTOR) and novel (Wnt-β-catenin and Eph-ephrin) cell signaling pathways that are activated in NPC spheroids. Targeting these pathways in 3D spheroids using FDA-approved drugs was effective in monoculture and co-culture. These findings provide the first demonstration of the establishment of EBV-positive and EBV-negative NPC 3D spheroids with features that resemble advanced and metastatic NPCs. Furthermore, we show that NPC spheroids have potential use in identifying new drug targets.

Long non‑coding RNA KCNQ1OT1 promotes nasopharyngeal carcinoma cell cisplatin resistance via the miR‑454/USP47 axis

Long non‑coding RNAs serve an essential role in drug resistance in various types of cancer, including lung, breast and bladder cancer. The present study aimed to investigate whether KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1) was associated with cisplatin (DDP) resistance in nasopharyngeal carcinoma (NPC). KCNQ1OT1, microRNA (miR)‑454 and ubiquitin specific peptidase 47 (USP47) expression levels were measured via reverse transcription‑quantitative PCR. 5‑8F/DDP and SUNE‑1/DDP cell viability and chemosensitivity were assessed by performing Cell Counting Kit‑8 assays. Colony forming and Transwell assays were conducted to assess the effect of the KCNQ1OT1/miR‑454/USP47 axis on DDP resistance in NPC cells. The association between miR‑454 and KCNQ1OT1 or USP47 was verified via bioinformatics analysis, dual‑luciferase reporter assays and RIP assays. KCNQ1OT1 and USP47 expression levels were significantly upregulated, whereas miR‑454 expression levels were significantly downregulated in DDP‑resistant NPC cells compared with parental NPC cells. KCNQ1OT1 knockdown promoted chemosensitivity in DDP‑resistant NPC cells (5‑8F/DDP and SUNE‑1/DDP), as indicated by significantly decreased cell proliferation, migration and invasion in the short hairpin RNA (sh)KCNQ1OT1 group compared with the sh‑negative control (NC) group. Moreover, miR‑454 was identified as a target of KCNQ1OT1. KCNQ1OT1 overexpression significantly reversed miR‑454 overexpression‑mediated effects on NPC cell viability and DDP resistance. Furthermore, the results indicated that miR‑454 directly targeted USP47. Compared with the shNC group, USP47 knockdown significantly suppressed NPC cell viability and DDP resistance, which was significantly reversed by co‑transfection with miR‑454 inhibitor. Furthermore, compared with the shNC group, KCNQ1OT1 knockdown significantly downregulated USP47 expression, which was significantly counteracted by miR‑454 knockdown. Collectively, the results of the present study indicated that KCNQ1OT1 enhanced DDP resistance in NPC cells via the miR‑454/USP47 axis, suggesting a potential therapeutic target for patients with DDP‑resistant NPC.

Targeting Cytoprotective Autophagy to Enhance Anticancer Therapies

Autophagy is a highly regulated multi-step process that occurs at the basal level in almost all cells. Although the deregulation of the autophagy process has been described in several pathologies, the role of autophagy in cancer as a cytoprotective mechanism is currently well established and supported by experimental and clinical evidence. Our understanding of the molecular mechanism of the autophagy process has largely contributed to defining how we can harness this process to improve the benefit of cancer therapies. While the role of autophagy in tumor resistance to chemotherapy is extensively documented, emerging data point toward autophagy as a mechanism of cancer resistance to radiotherapy, targeted therapy, and immunotherapy. Therefore, manipulating autophagy has emerged as a promising strategy to overcome tumor resistance to various anti-cancer therapies, and autophagy modulators are currently evaluated in combination therapies in several clinical trials. In this review, we will summarize our current knowledge of the impact of genetically and pharmacologically modulating autophagy genes and proteins, involved in the different steps of the autophagy process, on the therapeutic benefit of various cancer therapies. We will also briefly discuss the challenges and limitations to developing potent and selective autophagy inhibitors that could be used in ongoing clinical trials.

RIG-I promotes IFN/JAK2 expression and the endoplasmic reticulum stress response to inhibit chemoradiation resistance in nasopharyngeal carcinoma

RIG-I is associated with the occurrence and development of many tumors. However, the role of RIG-I in radiotherapy and chemotherapy in NPC has not been reported to date. In our study, RIG-I expression was significantly reduced in chemoradiotherapy-resistant NPC tissues and cells compared with that in therapy-sensitive tissues and cells. RIG-I expression increased in nonresistant NPC cells, including CNE1 and CNE2, in a dose-dependent manner with increasing chemotherapy drug concentration or radiotherapy dose. RIG-I overexpression promoted radiotherapy and chemotherapy sensitivity in NPC cells, leading to cellular apoptosis and increased expression of the proapoptotic factors BAX and caspase-3. Similarly, RIG-I knockdown in NPC cells promoted chemoradiotherapy resistance and reduced apoptosis. Analysis of microarray data indicated that the expression of IFN/JAK2 and endoplasmic reticulum (ER) stress response markers, such as JAK2, STAT1, IRF9, IFNB1, IRF3, p-IRF3, XBP1, ATF6, IFIT2, and ISG15, was inhibited in chemoradiotherapy-resistant cells compared with that in sensitive cells. Conversely, activation of IFN/JAK2 and ER stress response pathways in NPC cells reduced paclitaxel resistance and increased apoptosis. RIG-I promotes IFN/JAK2 and ER stress response-mediated apoptosis to inhibit chemoradiation resistance in nasopharyngeal carcinoma.

Overexpression of PRR11 promotes tumorigenic capability and is associated with progression in esophageal squamous cell carcinoma

INTRODUCTION

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies of gastrointestinal tract in the world, and the long-term prognosis for ESCC patients still remains dismal due to the lack of effective early diagnosis biomarkers.

MATERIALS AND METHODS

Western blot and immunochemistry were used to determine the expression of PRR11 in 201 clinicopathologically characterized ESCC specimens. The effects of PRR11 on stem cell-like traits and tumorigenicity were examined by tumor sphere formation assay and SP assays in vitro and by a tumorigenesis model in vivo. The mechanism by which PRR11 mediated Wnt/β-catenin signaling was explored using luciferase reporter, immuno-chemistry, and real time-PCR (RT-PCR) assays.

RESULTS

We found that PRR11 was markedly upregulated, at the level of both transcription and translation, in ESCC cell lines as compared with normal esophageal epithelial cells (NECCs). Immunohistochemical analysis showed that 69.2% paraffin-embedded archival ESCC specimens exhibited high levels of PRR11 expression, and multivariate analysis revealed that PRR11 upregulation might be an independent prognostic indicator for the survival of patients with ESCC. Furthermore, overexpression of PRR11 dramatically enhanced, whereas inhibition of PRR11 reduced the capability of cancer stem cell (CSC)-like phenotypes and tumorigenicity of ESCC cells both in vitro and in vivo. Mechanically, we demonstrated PRR11-enhanced tumorigenicity of ESCC cells via activating Wnt/β-catenin signaling, and PRR11 expression is found to be significantly correlated with β-catenin nuclear location in ESCC.

CONCLUSION

Our findings suggest that the PRR11 might represent a novel and valuable prognostic marker for ESCC progression and play a role during the development and progression of this malignancy.

iTRAQ-based quantitative proteomic analysis of differentially expressed proteins in chemoresistant nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a highly prevalent disease in Southeast Asia. The disease is typically diagnosed in the later stages, and chemotherapy resistance often causes treatment failure. To investigate the underlying mechanisms of drug resistance, we searched for chemoresistant-associated proteins in NPC and drug-resistant NPC cell lines using isobaric tags for relative and absolute quantitation combined with nano liquid chromatography-tandem mass spectrometry. The chemoresistant NPC cell lines CNE1DDP and CNE2DDP were resistant to 1 mg/L cisplatin, had resistant indexes of 4.58 and 2.63, respectively, and clearly grew more slowly than the NPC cell lines CNE1 and CNE2. Using three technical replicates, we identified 690 nonredundant proteins, 56 of which were differentially expressed in both groups of cell lines (CNE1 vs. CNE1DDP and CNE2 vs. CNE2DDP). Gene Ontology, KEGG pathway, and miRNA analyses and protein-protein interactions of differentially expressed proteins showed that proteins TRIM29, HSPB1, CLIC1, ANXA1, and STMN1, among others, may play a role in the mechanisms of chemoresistance in clinical therapy. The chemotherapy-resistant proteomic profiles obtained may allow the identification of novel biomarkers for early detection of chemoresistance in NPC and other cancers.

High expression of intratumoral stromal proteins is associated with chemotherapy resistance in breast cancer

We studied the changes of intratumoral stromal proteins including THBS1, TNC, FN, SPARC and α-SMA, following neoadjuvant chemotherapy. The underlying mechanisms by which THBS1 and TNC regulated resistance to docetaxel were further studied using functional studies. 100 patients with newly diagnosed breast cancer were treated with alternating sequential doxorubicin and docetaxel. Immunohistochemistry (IHC) staining for stromal proteins was performed on pre- and post-treatment core biopsies respectively. THBS1 and TNC were further validated with IHC in an independent cohort of 31 patients. A high baseline combined expression score of the 5 stromal proteins predicted independently for poor progression-free (HR_adjusted 2.22, 95% CI 1.06–4.64) and overall survival (HR_adjusted 5.94, 95% CI 2.25–15.71). After 1–2 cycles of chemotherapy, increased expression of THBS1, TNC, FN, SPARC and α-SMA was seen in patients with subsequent pathological lymph node involvement at surgery. Increased expression of THBS1 and TNC compared to baseline was also seen in intrinsically resistant tumors, but not in sensitive ones. Both THBS1 and TNC-associated chemoresistance were confirmed in an independent validation cohort. Exogenous THBS1 and TNC protected MCF-7 cells against proliferation inhibition induced by docetaxel through activating integrin β1/mTOR pathway. Thus, up-regulation of THBS1, TNC, FN, SPARC and α-SMA following neoadjuvant chemotherapy was associated with chemotherapy resistance in breast cancer patients. Functional studies showed THBS1 and TNC to mediate chemoresistance through the integrin β1/mTOR pathway, suggesting that therapies targeting integrin β1/mTOR pathway may be a promising strategy to overcome chemotherapy resistance.

Zoledronic acid reverses cisplatin resistance in nasopharyngeal carcinoma cells by activating the mitochondrial apoptotic pathway

Despite improvements to radiotherapeutic strategies, resistance to adjuvant chemotherapy remains the main problem underlying the low 5-year survival rate in patients with nasopharyngeal carcinoma (NPC). In the present study, the human NPC cell line HNE1 was exposed to gradually increasing concentrations of cisplatin (CDDP) in order to establish a drug-resistant sub-cell line, HNE1/CDDP. HNE1/CDDP cells exhibited multidrug resistance and a prolonged doubling time, as compared with the parent HNE1 cells. Furthermore, pretreatment with zoledronic acid (ZOL) appeared to resensitize the CDDP-resistant cells by inducing S-phase cell cycle arrest and the mitochondrial apoptotic pathway by upregulating the expression of B-cell lymphoma-2 (BCL-2)-associated X protein and caspase-9 and downregulating the expression of BCL-2. The results of the present study suggested that HNE1/CDDP cells are a stable, multidrug-resistant NPC cell line that may serve as an important tool for research in drug resistance. In addition, the application of ZOL may hold clinical therapeutic potential for the treatment of drug resistance in NPC.

MiR-1204 sensitizes nasopharyngeal carcinoma cells to paclitaxel both in vitro and in vivo

Nasopharyngeal carcinoma (NPC) is an endemic tumor with a relatively high incidence in Southern China and Southeast Asia. Paclitaxel combination chemotherapy has been used for treatment of advanced NPC. However, treatment failure often occurs due to development of acquired paclitaxel resistance. In this study, we first established a paclitaxel-resistant CNE-1/Taxol, HNE-2/Taxol and 5-8F/Taxol cell sublines by treating the parental CNE-1, HNE-2 and 5-8F cells with increasing doses of paclitaxel for about 5 months, respectively. Then, microRNA arrays were used to screen differentially expressed miRNAs between the CNE-1/Taxol cells and the parental CNE-1 cells. We found 13 differentially expressed miRNAs, of which miR-1204 was significantly downregulated in the paclitaxel-resistant CNE-1/Taxol cells. We restored miR-1204 expression in the CNE-1/Taxol, HNE-2/Taxol and 5-8F/Taxol cells and found that restoration of miR-1204 re-sensitized the paclitaxel-resistant CNE-1/Taxol, HNE-2/Taxol and 5-8F/Taxol cells to paclitaxel both in vitro. Finally, we demonstrated that restoration of miR-1204 in significantly inhibits tumor growth in vivo. Thus, our study provides important information for the development of targeted gene therapy for reversing paclitaxel resistance in NPC.

FOXC2 promotes chemoresistance in nasopharyngeal carcinomas via induction of epithelial mesenchymal transition

Paclitaxel (Taxol) is currently used as the front-line chemotherapeutic drug for many types of human cancers. However, the emergence of drug resistance has been a major obstacle to the effective treatment of cancers in clinical settings. The transcription factor Forkhead box protein C2 (FOXC2) was recently demonstrated to activate the epithelial-mesenchymal transition (EMT). In this article, we present a novel role of FOXC2 in regulating chemoresistance of nasopharyngeal carcinoma (NPC) through the EMT. Using an EMT PCR array based on the screening of 84 genes, the expression of FOXC2 was notably upregulated in paclitaxel-resistant NPC cells (CNE2/t). We observed that the paclitaxel-resistant cells exhibited characteristic EMT phenotypes. The silencing of FOXC2 expression in the resistant cells can reverse the EMT molecular markers and chemoresistant phenotypes, such as cellular morphology, proliferation and anoikis. In an NPC xenograft mouse model, the downregulation of FOXC2 expression in the resistant NPC cells increased their sensitivity to paclitaxel treatment, resulting in reduced tumor growth. Taken together, our results suggest that FOXC2-mediated EMT may be an alternative mechanism through which cancer cells can initiate and maintain drug resistance. Thus, targeting FOXC2 may provide a novel strategy for overcoming chemoresistance in NPC therapy.

Anti-angiogenic pathway associations of the 3p21.3 mapped BLU gene in nasopharyngeal carcinoma

Zinc-finger, MYND-type containing 10 (ZMYND10), or more commonly called BLU, expression is frequently downregulated in nasopharyngeal carcinoma (NPC) and many other tumors due to promoter hypermethylation. Functional evidence shows that the BLU gene inhibits tumor growth in animal assays, but the detailed molecular mechanism responsible for this is still not well understood. In current studies, we find that 93.5% of early-stage primary NPC tumors show downregulated BLU expression. Using a PCR array, overexpression of the BLU gene was correlated to the angiogenesis network in NPC cells. Moreover, expression changes of the MMP family, VEGF and TSP1, were often detected in different stages of NPC, suggesting the possibility that BLU may be directly involved in the microenvironment and anti-angiogenic activity in NPC development. Compared with vector-alone control cells, BLU stable transfectants, derived from poorly-differentiated NPC HONE1 cells, suppress VEGF165, VEGF189 and TSP1 expression at both the RNA and protein levels, and significantly reduce the secreted VEGF protein in these cells, reflecting an unknown regulatory mechanism mediated by the BLU gene in NPC. Cells expressing BLU inhibited cellular invasion, migration and tube formation. These in vitro results were further confirmed by in vivo tumor suppression and a matrigel plug angiogenesis assay in nude mice. Tube-forming ability was clearly inhibited, when the BLU gene is expressed in these cells. Up to 70-90% of injected tumor cells expressing increased exogenous BLU underwent cell death in animal assays. Overexpressed BLU only inhibited VEGF165 expression in differentiated squamous NPC HK1 cells, but also showed an anti-angiogenic effect in the animal assay, revealing a complicated mechanism regulating angiogenesis and the microenvironment in different NPC cell lines. Results of these studies indicate that alteration of BLU gene expression influences anti-angiogenesis pathways and is important for the development of NPC.

Txr1: an important factor in oxaliplatin resistance in gastric cancer

Oxaliplatin-based chemotherapy is the main treatment regimen for gastric cancer (GC), but can fail because of drug resistance. We investigated the role of a recently identified drug-resistance gene, taxol-resistant gene 1 (Txr1), in oxaliplatin resistance. A retrospective study based on banked tissue was carried out. We collected clinical data from 95 patients with stage II-III GC who were treated with radical D2 surgery and standardized first-line chemotherapy with oxaliplatin; paraffin blocks of their tumor specimens were prepared for a tissue microarray in which Txr1 expression was analyzed immunohistochemically and compared with their clinical data and their 3-year disease-free survival (DFS) rate. The human GC cell line, SGC7901, was developed into the oxaliplatin-resistant cell line, SGC7901/L-OHP, using slowly increased oxaliplatin concentrations over 6 months. The relationship between Txr1 expression and drug-resistance of oxaliplatin in GC was studied with drug intervention, gene silencing technology, real-time PCR and Western blot analysis. Of the 95 patients with GC, those with TXR1(-) GC had longer postoperative 3-year DFS (77.8 %) than those with TXR1(+) GC (52.9 %). In oxaliplatin-resistant SGC7901/L-OHP cells, the main expression location of Txr1 shifted from the nucleus to cytoplasm, and both the mRNA and protein expression of Txr1 were higher than that of the parental cells, whereas expression of thrombospondin-1 (TSP1) decreased. When the Txr1 gene was silenced, TSP1 expression increased and the oxaliplatin resistance was significantly reduced in SGC7901/L-OHP cells. Changed Txr1 expression in GC affects the efficacy of oxaliplatin-based chemotherapy. Increased Txr1 expression decreases TSP1 expression and inhibits apoptosis. Txr1 could be a target in reversing oxaliplatin resistance in GC.

Extracellular matrix proteins modulate antimigratory and apoptotic effects of Doxorubicin

Anticancer drug resistance is a multifactorial process that includes acquired and de novo drug resistances. Acquired resistance develops during treatment, while de novo resistance is the primary way for tumor cells to escape chemotherapy. Tumor microenvironment has been recently shown to be one of the important factors contributing to de novo resistance and called environment-mediated drug resistance (EMDR). Two forms of EMDR have been described: soluble factor-mediated drug resistance (SFM-DR) and cell adhesion-mediated drug resistance (CAM-DR). Anthracyclines, among the most potent chemotherapeutic agents, are widely used in clinics against hematopoietic and solid tumors. Their main mechanism of action relies on the inhibition of topoisomerase I and/or II and the induction of apoptosis. Beyond this well-known antitumor activity, it has been recently demonstrated that anthracyclines may display potent anti-invasive effects when used at subtoxic concentrations. In this paper, we will describe two particular modes of EMDR by which microenvironment may influence tumor-cell response to one of these anthracyclines, doxorubicin. The first one considers the influence of type I collagen on the antimigratory effect of doxorubicin (CAM-DR). The second considers the protection of tumor cells by thrombospondin-I against doxorubicin-induced apoptosis (SFM-DR).

Inhibition of α Folate Receptor Resulting in a Reversal of Taxol Resistance in Nasopharyngeal Carcinoma

Objective. To further determine the role of FOLR1 in taxol resistance of nasopharyngeal carcinoma (NPC) and whether inhibition of FOLR1 expression reverses the taxol-resistant phenotype.

Study Design. Correlation study between gene expression and cancer cell survival.

Setting. University hospital.

Subjects and Methods. Three taxol-resistant sub–cell lines with a different resistant index were established from the parental CNE-1 NPC cell line. The correlation between FOLR1 expression and taxol sensitivity was statistically analyzed. Inhibition of FOLR1 expression was carried out by RNA interference and by a FOLR1-specific monoclonal antibody, and taxol sensitivity was examined by colony formation assays. FOLR1 expression was also examined in 72 NPC patient specimens by immunohistochemistry.

Results. The levels of FOLR1 expression were positively and significantly correlated with a taxol resistance phenotype ( P < .05). Inhibition of FOLR1 expression resulted in a significantly increased sensitivity of taxol to taxol-resistant NPC cells ( P < .05). An increase of FOLR1 expression by gene transfection caused a taxol-resistant phenotype in parental NPC cells. The level of FOLR1 expression was found to be related to clinical stage in NPC tissue samples.

Conclusion. These results suggest that FOLR1 plays an important role in taxol resistance of NPC cells.