Anterior gradient protein 2 expression in high grade head and neck squamous cell carcinoma correlated with cancer stem cell and epithelial mesenchymal transition

Cancer stem cells of head and neck squamous cell carcinoma; distance towards clinical application; a systematic review of literature

Head and neck squamous cell carcinoma (HNSCC) is the major pathological type of head and neck cancer (HNC). The disease ranks sixth among the most common malignancies worldwide, with an increasing incidence rate yearly. Despite the development of therapy, the prognosis of HNSCC remains unsatisfactory, which may be attributed to the resistance to traditional radio-chemotherapy, relapse, and metastasis. To improve the diagnosis and treatment, the targeted therapy for HNSCC may be successful as that for some other tumors. Nanocarriers are the most effective system to deliver the anti-cancerous agent at the site of interest using passive or active targeting approaches. The system enhances the drug concentration in HCN target cells, increases retention, and reduces toxicity to normal cells. Among the different techniques in nanotechnology, quantum dots (QDs) possess multiple fluorescent colors emissions under single-source excitation and size-tunable light emission. Dendrimers are the most attractive nanocarriers, which possess the desired properties of drug retention, release, unaffecting by the immune system, blood circulation time enhancing, and cells or organs specific targeting properties. In this review, we have discussed the up-to-date knowledge of the Cancer Stem Cells of Head and Neck Squamous Cell Carcinoma. Although a lot of data is available, still much more efforts remain to be made to improve the treatment of HNSCC.

The Role of ARHGAP1 in Rho GTPase Inactivation during Metastasizing of Breast Cancer Cell Line MCF-7 after Treatment with Doxorubicin

Breast cancer is the most prevalent cancer type in women worldwide. It proliferates rapidly and can metastasize into farther tissues at any stage due to the gradual invasiveness and motility of the tumor cells. These crucial properties are the outcome of the weakened intercellular adhesion, regulated by small guanosine triphosphatases (GTPases), which hydrolyze to the guanosine diphosphate (GDP)-bound conformation. We investigated the inactivating effect of ARHGAP1 on Rho GTPases involved signaling pathways after treatment with a high dose of doxorubicin. Label-free quantitative proteomic analysis of the proteome isolated from the MCF-7 breast cancer cell line, treated with 1 μM of doxorubicin, identified RAC1, CDC42, and RHOA GTPases that were inactivated by the ARHGAP1 protein. Upregulation of the GTPases involved in the transforming growth factor-beta (TGF-beta) signaling pathway initiated epithelial-mesenchymal transitions. These findings demonstrate a key role of the ARHGAP1 protein in the disruption of the cell adhesion and simultaneously allow for a better understanding of the molecular mechanism of the reduced cell adhesion leading to the subsequent metastasis. The conclusions of this study corroborate the hypothesis that chemotherapy with doxorubicin may increase the risk of metastases in drug-resistant breast cancer cells.

Can Immunoexpression of Cancer Stem Cell Markers Prognosticate Tongue Squamous Cell Carcinoma? A Systematic Review and Meta-Analysis

The objective was to evaluate the association of the immunoexpression of cancer stem cell (CSC) markers with clinicopathological and survival outcomes in tongue squamous cell carcinoma (TSCC) patients. This systematic review and meta-analysis [PROSPERO (CRD42021226791)] included observational studies that compared the association of clinicopathological and survival outcomes with CSC immunoexpression in TSCC patients. Pooled odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (CI) were used as outcome measures. Six studies identified the association with three surface markers (c-MET, STAT3, CD44) and four transcription markers (NANOG, OCT4, BMI, SOX2). The odds of early-stage presentation were 41% (OR = 0.59, 95% CI 0.42-0.83) and 75% (OR = 0.25; 95% CI 0.14-0.45) lower in CSC and SOX2 immuno-positive cases than immuno-negative cases, respectively. The odds of well-differentiated tumors in transcription marker immuno-positive cases were 45% lower compared to immuno-negative cases (OR = 0.55, 95% CI 0.32-0.96). The odds of positive lymph nodes were 2.01 times higher in CSC immuno-positive cases compared to immuno-negative cases (OR = 2.01, 95% CI 1.11-3.65). Mortality in immuno-positive cases was 121% higher than that in immuno-negative cases (HR = 2.21; 95% CI 1.16-4.21). Advanced tumor staging and grading, lymph node metastasis, and mortality were significantly associated with positive immunoexpression of CSC markers.

Expression of KAI1 and AGR2 in lung adenocarcinoma and their clinicopathological significance

OBJECTIVE

Anticancer 1 (KAI1, tumor metastasis suppressor gene) and Anterior gradient-2 (AGR2, considered a valuable prognostic factor for some cancers) are associated with metastasis and prognosis of various types of human cancers. Nevertheless, the relationship between KAI1 and AGR2 in lung adenocarcinoma (LUAD) remains unclear. In this research, we analyzed the correlations between KAI1 and AGR2 in LUAD, and explored their correlations with clinicopathological parameters and overall survival time (OS) in patients with LUAD.

METHODS

Immunohistochemical staining was used to detect KAI1 and AGR2 expression in 132 cases of LUAD samples. At the same time, all clinicopathological parameters and postoperative survival information were collected.

RESULTS

AGR2 positive rate was significantly increased and KAI1 positive rate was significantly decreased in LUAD and control tissues. KAI1 positive rates were negatively correlated with tumor stage, LNM stage and TNM stage, and KAI1 subgroup positive expression of OS was significantly higher than negative KAI1 subgroup. The positive rate of AGR2 was positively correlated with tumor grade, LNM stage and TNM stage, and negatively correlated with patients OS. Active expression of AGR2 and KAI1, tumor stage, and LNM stage in multivariate analyses may be independent prognostic factors for OS in LUAD patients.

CONCLUSION

KAI1 and AGR2 may be potential biomarkers for prognosis and metastasis, and they are also promising therapeutic targets for LUAD patients.

The anterior gradient homologue 2 (AGR2) co-localises with the glucose-regulated protein 78 (GRP78) in cancer stem cells, and is critical for the survival and drug resistance of recurrent glioblastoma: in situ and in vitro analyses

BACKGROUND

Glioblastomas (GBs) are characterised as one of the most aggressive primary central nervous system tumours (CNSTs). Single-cell sequencing analysis identified the presence of a highly heterogeneous population of cancer stem cells (CSCs). The proteins anterior gradient homologue 2 (AGR2) and glucose-regulated protein 78 (GRP78) are known to play critical roles in regulating unfolded protein response (UPR) machinery. The UPR machinery influences cell survival, migration, invasion and drug resistance. Hence, we investigated the role of AGR2 in drug-resistant recurrent glioblastoma cells.

METHODS

Immunofluorescence, biological assessments and whole exome sequencing analyses were completed under in situ and in vitro conditions. Cells were treated with CNSTs clinical/preclinical drugs taxol, cisplatin, irinotecan, MCK8866, etoposide, and temozolomide, then resistant cells were analysed for the expression of AGR2. AGR2 was repressed using single and double siRNA transfections and combined with either temozolomide or irinotecan.

RESULTS

Genomic and biological characterisations of the AGR2-expressed Jed66_GB and Jed41_GB recurrent glioblastoma tissues and cell lines showed features consistent with glioblastoma. Immunofluorescence data indicated that AGR2 co-localised with the UPR marker GRP78 in both the tissue and their corresponding primary cell lines. AGR2 and GRP78 were highly expressed in glioblastoma CSCs. Following treatment with the aforementioned drugs, all drug-surviving cells showed high expression of AGR2. Prolonged siRNA repression of a particular region in AGR2 exon 2 reduced AGR2 protein expression and led to lower cell densities in both cell lines. Co-treatments using AGR2 exon 2B siRNA in conjunction with temozolomide or irinotecan had partially synergistic effects. The slight reduction of AGR2 expression increased nuclear Caspase-3 activation in both cell lines and caused multinucleation in the Jed66_GB cell line.

CONCLUSIONS

AGR2 is highly expressed in UPR-active CSCs and drug-resistant GB cells, and its repression leads to apoptosis, via multiple pathways.

AGR2 expression as a predictive biomarker for therapy response in esophageal squamous cell carcinoma

Despite multidisciplinary therapy, the prognosis is poor for esophageal squamous cell carcinoma (ESCC). In the locally advanced stage, neoadjuvant chemoradiotherapy (nCRT) followed by surgery could provide survival benefits to some patients. Here, we aimed to identify for tumor therapy response a biomarker based on RNA sequencing. We collected endoscopic biopsies of 32 ESCC patients, who were divided according to nCRT response, into two groups: the complete response group (n  =  13) and the non-complete response group (n  =  19). RNA-sequencing data showed that 464 genes were differentially expressed. Increased in non-complete response group, 4 genes increased expressions were AGR2 (anterior gradient 2), GADD45B (growth arrest and DNA damage inducible beta), PPP1R15A (protein phosphatase 1 regulatory subunit 15A) and LRG1 (leucine rich alpha-2-glycoprotein 1). The areas under the curve (AUC) of the AGR2 gene was 0.671 according to read counts of RNA-seq and therapy response of nCRT. In vitro study showed that apoptosis cell was significantly increased in the AGR2-knockdown TE-2 cell line treated with cisplatin and 5-Fluorouracil (5-FU), when compared with si-control. Results suggest that in ESCC, the AGR2 gene is a promising and predictive gene marker for the response to anti-tumor therapy.

Anterior gradient proteins in gastrointestinal cancers: from cell biology to pathophysiology

Most of the organs of the digestive tract comprise secretory epithelia that require specialized molecular machines to achieve their functions. As such anterior gradient (AGR) proteins, which comprise AGR1, AGR2, and AGR3, belong to the protein disulfide isomerase family, and are involved in secretory and transmembrane protein biogenesis in the endoplasmic reticulum. They are generally expressed in epithelial cells with high levels in most of the digestive tract epithelia. To date, the vast majority of the reports concern AGR2, which has been shown to exhibit various subcellular localizations and exert pro-oncogenic functions. AGR2 overexpression has recently been associated with a poor prognosis in digestive cancers. AGR2 is also involved in epithelial homeostasis. Its deletion in mice results in severe diffuse gut inflammation, whereas in inflammatory bowel diseases, the secretion of AGR2 in the extracellular milieu participates in the reshaping of the cellular microenvironment. AGR2 thus plays a key role in inflammation and oncogenesis and may represent a therapeutic target of interest. In this review, we summarize the already known roles and mechanisms of action of the AGR family proteins in digestive diseases, their expression in the healthy digestive tract, and in digestive oncology. At last, we discuss the potential diagnostic and therapeutic implications underlying the biology of AGR proteins.

From development to cancer - an ever-increasing role of AGR2

Anterior gradient 2, AGR2, is a small, 20 kDa protein that plays a vital role in oxidative protein folding in the endoplasmic reticulum. AGR2 is involved in several signal transduction pathways that are essential for cell survival. It was initially discovered in the African clawed frog, Xenopus laevis, where it plays an important function in embryonic development. Akin to several other developmental genes, it is also frequently deregulated in cancer, where it plays a decisive role in tumor initiation, progression and metastasis. In this review, we have summarized currently known AGR2 functions, its expression and function in embryonic and cancer development, as well as its potential as a candidate tumor biomarker and promising new target for cancer immunotherapy.

Anterior gradient 2 regulates cancer progression in TP53‑wild‑type esophageal squamous cell carcinoma

Anterior gradient 2 (AGR2) reportedly promotes tumor growth and has an unfavorable impact on survival in several cancers. However, no comprehensive functional analysis of AGR2 in esophageal squamous cell carcinoma (ESCC) has been performed. In the present study, the function and clinical significance of AGR2 were examined using ESCC cell lines and clinical samples. AGR2 was upregulated in EC tissue and ESCC cell lines. The downregulation of AGR2 suppressed cell proliferation and increased the proportion of G2/M‑phase cells and phosphorylation of p53 in TP53‑wild‑type ESCC and osteosarcoma cells. However, these changes were not observed in TP53‑mutant ESCC cells. In addition, immunohistochemistry results demonstrated that high AGR2 and low p53 expression levels in ESCC tissues were correlated with a worse prognosis. These results suggested that although AGR2 enhanced cell proliferation by inhibiting p53 phosphorylation in TP53‑wild‑type ESCC, the same mechanism did not regulate cell functions in TP53‑mutant ESCC. Thus, AGR2 served an important role in ESCC progression and might be a useful prognostic marker in patients with TP53‑wild‑type ESCC.

Discrimination of Cancer Stem Cell Markers ALDH1A1, BCL11B, BMI-1, and CD44 in Different Tissues of HNSCC Patients

Cancer stem cells (CSCs) are accountable for the progress of head and neck squamous cell carcinoma (HNSCC). This exploratory study evaluated the expression of molecular CSC markers in different tissues of HNSCC patients. Tissue specimens of primary tumor, lymph node metastases and macroscopically healthy mucosa of 12 consecutive HNSCC patients, that were treated with surgery and adjuvant radio(chemo)therapy upon indication, were collected. Samples were assessed for the expression of p16 as a surrogate for HPV-related disease and different molecular stem cell markers (ALDH1A1, BCL11B, BMI-1, and CD44). In the cohort, seven patients had HPV-related HNSCC; six thereof were oropharyngeal squamous cell carcinoma. While expression of BMI-1 and BCL11B was significantly lower in healthy mucosa than both tumor and lymph node metastasis, there were no differences between tumor and lymph node metastasis. In the HPV-positive sub-cohort, these differences remained significant for BMI-1. However, no significant differences in these three tissues were found for ALDH1A1 and CD44. In conclusion, this exploratory study shows that CSC markers BMI-1 and BCL11B discriminate between healthy and cancerous tissue, whereas ALDH1A1 and CD44 were expressed to a comparable extent in healthy mucosa and cancerous tissues.

Intracellular AGR2 transduces PGE2 stimuli to promote epithelial-mesenchymal transition and metastasis of colorectal cancer

Human anterior gradient homolog 2 (AGR2) reportedly acts as an oncogene in multiple types of cancers. As a secreted protein, the oncogenic roles of extracellular AGR2 have been the focus of the increasing number of studies. In contrast, the oncological functions of intracellular AGR2 (iAGR2) remain elusive. Here, we report that intracellular AGR2 (iAGR2) is sufficient to promote CRC metastasis. iAGR2 binds to KDEL receptors (KDELRs) via its KTEL motif to activate downstream Gs-PKA signaling. Activated PKA upregulates the expression of NF-κB subunit c-Rel (REL) and acetylates histone H3 at lysine 9 (H3K9ac) to promote the transcription of SNAIL and SLUG. AGR2 can be upregulated by prostaglandin E2 (PGE2) via EP4-PI3K-AKT pathway and is indispensable for PGE2-induced CRC metastasis. AGR2 knockdown enhances therapeutic effects of a COX-2 inhibitor, celecoxib, in CRC metastasis. Collectively, our study reveals a promoting role and molecular mechanisms of iAGR2 in CRC metastasis and uncovers a new tumor microenvironment signal regulating AGR2 expression, which may provide new targets for treating metastatic CRC.

Secretion of pro-oncogenic AGR2 protein in cancer

Anterior gradient-2 (AGR2) protein mediates the formation, breakage and isomerization of disulphide bonds during protein maturation in the endoplasmic reticulum (ER) and contributes to the homoeostasis of the secretory pathway. AGR2 promotes tumour development and metastasis and its elevated expression is almost completely restricted to malignant tumours. Interestingly, this supposedly ER-resident protein can be localised to other compartments of cancer cells and can also be secreted into the extracellular milieu. There are emerging evidences that describe the gain-of-function activities of the extracellular AGR2, particularly in cancer development. Here, we reviewed studies detailing the expression, pathological and physiological roles associated with AGR2 and compared the duality of localization, intracellular and extracellular, with special emphasis on the later. We also discussed the possible mechanisms of AGR2 secretion as well as deliberating the functional impacts of AGR2 in cancer settings. Last, we deliberate the current therapeutic strategies and posit the potential use AGR2, as a prognosis and diagnosis marker in cancer.

Expression of NANOG and Its Regulation in Oral Squamous Cell Carcinoma

Background

Results of previous studies suggest that NANOG may be an important prognostic biomarker in oral squamous cell carcinoma (OSCC), but there are contradictory results regarding NANOG expression patterns on mRNA and protein levels, and the mechanisms of its regulation are poorly understood. Our aim was to analyze the expression and diagnostic significance of NANOG in OSCC, and the possible mechanisms of its regulation, i.e., protein regulators on mRNA level (OCT4, SOX2, KLF4, AGR2, and NOTCH1), methylation status, copy number variation, and regulatory miRNAs, miR-145, miR-335, miR-150, miR-34a, miR-128, and miR-27a.

Methods

Our study included 120 patients with OSCC. Expression of NANOG protein and mRNA was analyzed using immunohistochemistry and qPCR. Expression of regulatory factors, miRNAs, and copy number variation was performed using qPCR. Methylation status of NANOG promoter was determined using PCR and Sanger sequencing.

Results

We detected upregulation of NANOG and OCT4 and downregulation of NOTCH1 and AGR2 mRNA in OSCC with lymph node metastases compared to OSCC without lymph node metastases. We observed a strong positive correlation between mRNAs of NANOG and those of its protein regulators OCT4, SOX2, NOTCH1, AGR2, and KLF4. The expression of NANOG was in positive correlation with the expression of miR-34a. There was also a correlation between T status of OSCC and the expression of miR-335 and miR-150 and a correlation of miR-150 with the N status of T2 OSCC. NANOG promoter methylation and copy number variation were only observed in a small proportion of samples.

Conclusions

Our findings confirm the diagnostic significance of NANOG in OSCC and provide information on NANOG expression patterns on both mRNA and protein levels. They also suggest that protein regulators and microRNAs might play a crucial role, whereas methylation of its promoter and copy number variation probably have a minor role in the regulation of NANOG expression in OSCC.

Role of cancer stem cell markers ALDH1, BCL11B, BMI-1, and CD44 in the prognosis of advanced HNSCC

Purpose

Cancer stem cells (CSCs) are held accountable for the progress of head and neck squamous cell carcinoma (HNSCC). In the presented study, the authors evaluated the prognostic value of CSC markers in two particular HNSCC cohorts.

Methods

This two cohort study consisted of 85 patients with advanced stage HNSCC, treated with primary radio(chemo)therapy (pRCT), and 95 patients with HNSCC, treated with surgery and partially adjuvant radio(chemo)therapy. Overall survival (OS), disease-free survival (DFS), and disease-specific survival (DSS) were assessed. Samples were assessed for the expression of different molecular stem cell markers (ALDH1, BCL11B, BMI‑1, and CD44).

Results

In the pRCT cohort, none of the baseline patient and tumor features exhibited a statistically significant relation with survival in either the cohort or the human papillomavirus (HPV)-stratified subcohorts. High expression of BMI‑1 significantly decreased OS and DFS, while high expression of CD44 decreased all modes of survival. Multivariate analysis showed significant prognostic influence for all tested CSC markers, with high BMI‑1 and CD44 decreasing survival (BMI-1: OS, DFS, DSS; CD44: OS, DFS) and high ALDH1 and BCL11B showing a beneficial effect on survival (ALDH1: OS, DFS; BCL11B: OS, DSS). In the surgical cohort, classical prognosticators such as HPV status, R1 resection, and nodal status in HPV-negative HNSCC played a significant role, but the tested CSC markers showed no significant effect on prognosis.

Conclusion

Although validation in independent cohorts is still needed, testing for CSC markers in patients with advanced or late stage HNSCC might be beneficial, especially if many comorbidities exist or disease is irresectable. The findings might guide the development and earlier use of targeted therapies in the future.

Electronic supplementary material

The online version of this article (10.1007/s00066-020-01653-5) contains supplementary material, which is available to authorized users.

Leveraging the Role of the Metastatic Associated Protein Anterior Gradient Homologue 2 in Unfolded Protein Degradation: A Novel Therapeutic Biomarker for Cancer

Effective diagnostic, prognostic and therapeutic biomarkers can help in tracking disease progress, predict patients’ survival, and considerably affect the drive for successful clinical management. The present review aims to determine how the metastatic-linked protein anterior gradient homologue 2 (AGR2) operates to affect cancer progression, and to identify associated potential diagnostic, prognostic and therapeutic biomarkers, particularly in central nervous system (CNS) tumors. Studies that show a high expression level of AGR2, and associate the protein expression with the resilience to chemotherapeutic treatments or with poor cancer survival, are reported. The primary protein structures of the seven variants of AGR2, including their functional domains, are summarized. Based on experiments in various biological models, this review shows an orchestra of multiple molecules that regulate AGR2 expression, including a feedback loop with p53. The AGR2-associated molecular functions and pathways including genomic integrity, proliferation, apoptosis, angiogenesis, adhesion, migration, stemness, and inflammation, are detailed. In addition, the mechanisms that can enable the rampant oncogenic effects of AGR2 are clarified. The different strategies used to therapeutically target AGR2-positive cancer cells are evaluated in light of the current evidence. Moreover, novel associated pathways and clinically relevant deregulated genes in AGR2 high CNS tumors are identified using a meta-analysis approach.

Heterogeneity of Head and Neck Squamous Cell Carcinoma Stem Cells

Current systemic cancer treatment in head and neck squamous cell carcinoma (HNSCC) is moving toward more personalized approaches such as de-escalation protocols human-papilloma-virus dependent HNSCC or application of checkpoint inhibitors. However, these treatments have been challenged by cancer stem cells (CSC), a small population within the bulk tumor, which are leading to treatment failure, tumor recurrence, or metastases. This review will give an overview of the characteristics of HNSCC-CSC. Specifically, the mechanisms by which HNSCC-CSC induce tumor initiation, progression, recurrence, or metastasis will be discussed. Although evidence-based treatment options targeting HNSCC-CSC specifically are still being sought for, they warrant a promise for additional and sustainable treatment options where for HNSCC patients where others have failed.

Overexpression of Golgi Phosphoprotein 2 Is Associated With Poor Prognosis in Oral Squamous Cell Carcinoma

OBJECTIVES

The aims of this study were to investigate the relationship between Golgi phosphoprotein 2 (GOLPH2) and oral squamous cell carcinoma (OSCC) and explore the clinical significance of GOLPH2 in OSCC.

METHODS

Tissue microarrays from human OSCC samples were stained for GOLPH2 expression and clinicopathologic features. Kaplan-Meier analysis was used to compare the survival of patients with high GOLPH2 expression and patients with low GOLPH2 expression.

RESULTS

We found GOLPH2 is highly expressed in OSCC tissue, and the GOLPH2 expression in metastatic lymph nodes is higher than in tumor tissue. Our data indicate that patients with higher GOLPH2 expression have poor overall survival compared with those with lower GOLPH2 expression. This study demonstrated that GOLPH2 was associated with CD44, SOX2, Slug, B7-H3, B7-H4, TIM3, and VISTA.

CONCLUSIONS

These findings suggest GOLPH2 is a potential marker for estimating the patient's prognosis and may be a target for molecular-targeted therapy against OSCC.

CD317 Signature in Head and Neck Cancer Indicates Poor Prognosis

Targeted therapy using monoclonal antibodies (mAbs) has emerged as a widely used form of immunotherapy in head and neck squamous cell carcinoma (HNSCC). Membrane-associated glycoprotein CD317 has been preferentially overexpressed by multiple myeloma cells, and its humanized mAb has been previously used in clinical trials. However, overexpression of CD317 in HNSCC and its correlation with tumor immunity is still uncertain. Here, the immunoreactivity of CD317 was detected in human HNSCC tissue microarrays, which contained 43 oral mucosa samples, 48 dysplasia samples, and 165 primary HNSCC. We found that CD317 expression was up-regulated in HNSCC tumor cells, and the CD317 expression level was independent of the histological grade, tumor size, and lymph node metastasis. Moreover, Kaplan–Meier survival curve analysis showed that patients with high expression of CD317 had a poor prognosis compared with patients with low expression. Furthermore, CD317 overexpression in HNSCC was correlated with immune checkpoint molecules PD-L1, B7-H3, and B7-H4 and tumor-associated macrophage markers (CD68 and CD163). We also observed that CD317 was overexpressed in immunocompetent mouse HNSCC tissue compared with normal tissue. Taken together, our findings demonstrate that CD317 overexpression indicates poor prognosis and is correlated with immune-related components in this patient cohort. CD317 may serve as a potential target for effective immunotherapy of HNSCC.

Dihydromyricetin promotes autophagy and apoptosis through ROS-STAT3 signaling in head and neck squamous cell carcinoma

Chemotherapy is an effective weapon in the battle against cancer, but numerous cancer patients are either not sensitive to chemotherapy or develop drug resistance to current chemotherapy regimens. Therefore, an effective chemotherapy mechanism that enhances tumor sensitivity to chemotherapeutics is urgently needed. The aim of the present study was to determine the antitumor activity of dihydromyricetin (DHM) on head and neck squamous cell carcinoma (HNSCC) and its underlying mechanisms. We demonstrated that DHM can markedly induce apoptotic cell death and autophagy in HNSCC cells. Meanwhile, increased autophagy inhibited apoptosis. Pharmacological or genetic inhibition of autophagy further sensitized the HNSCC cells to DHM-induced apoptosis. Mechanistic analysis showed that the antitumor of DHM may be due to the activation phosphorylation of signal transducer and activator of transcription 3 (p-STAT3), which contributed to autophagy. Importantly, DHM triggered reactive oxygen species (ROS) generation in the HNSCC cells and the levels of ROS decreased with N-acetyl-cysteine (NAC), a ROS scavenger. Moreover, NAC abrogated the effects of DHM on STAT3-dependent autophagy. Overall, the following critical issues were observed: first, DHM increased the p-STAT3-dependent autophagy by generating ROS-signaling pathways in head and neck squamous cell carcinoma. Second, inhibiting autophagy could enhance DHM-induced apoptosis in head and neck squamous cell carcinoma.

RNA sequencing reveals widespread transcriptome changes in a renal carcinoma cell line

We used RNA sequencing (RNA-Seq) technology to investigate changes in the transcriptome profile in the Caki-1 clear cell renal cell carcinoma (ccRCC) cells, which overexpress monocyte chemoattractant protein-induced protein 1 (MCPIP1). RNA-Seq data showed changes in 11.6% and 41.8% of the global transcriptome of Caki-1 cells overexpressing wild-type MCPIP1 or its D141N mutant, respectively. Gene ontology and KEGG pathway functional analyses showed that these transcripts encoded proteins involved in cell cycle progression, protein folding in the endoplasmic reticulum, hypoxia response and cell signalling. We identified 219 downregulated transcripts in MCPIP1-expressing cells that were either unchanged or upregulated in D141N-expressing cells. We validated downregulation of 15 transcripts belonging to different functional pathways by qRT-PCR. The growth and viability of MCPIP1-expressing cells was reduced because of elevated p21Cip1 levels. MCPIP1-expressing cells also showed reduced levels of DDB1 transcript that encodes component of the E3 ubiquitin ligase that degrades p21Cip1. These results demonstrate that MCPIP1 influences the growth and viability of ccRCC cells by increasing or decreasing the transcript levels for proteins involved in cell cycle progression, protein folding, hypoxia response, and cell signaling.

Associations of MACC1, AGR2, and KAI1 expression with the metastasis and prognosis in head and neck squamous cell carcinoma

BACKGROUND

Metastasis-associated in colon cancer-1 (MACC1, was firstly found in colon cancer and associated metastasis and prognosis in various cancers), anterior gradient 2 (AGR2, was considered as a valuable prognostic factor for some cancers), and Kangai 1 (KAI1, was a tumor metastasis suppressor gene) are all related to metastasis and prognosis of many cancers. However, the associations of MACC1, AGR2, and KAI1 in head and neck squamous cell carcinoma (HNSCC) are still unclear. In this study, we analyzed associations among MACC1, AGR2, and KAI1 in HNSCC, and their respective associations with clinicopathological parameters and overall survival (OS) in HNSCC.

METHODS

Positive expression of MACC1, AGR2, and KAI1 in 106 whole HNSCC tissue samples was detected by immunohistochemical staining. Patient's clinical data and demographics were both collected.

RESULTS

Positive rates of MACC1 and AGR2 were significantly higher, and positive rate of KAI1 was significantly lower, in HNSCC and than those in control tissues. Positive rates of MACC1 and AGR2 were positively correlated with grades of tumor, TNM stages, and lymph node metastasis (LNM) stages, and negatively with patients OS; positive rate of KAI1 was negatively associated with grades of tumor, TNM stages, and LNM stages, and the positive expression of KAI1 subgroup had significantly longer OS than did the negative KAI1 subgroup. In multivariate analysis, positive expression MACC1, AGR2, and KAI1, and tumor stages, as well as LNM stages were potential to be independent prognostic factors for OS in patients with HNSCC.

CONCLUSIONS

MACC1, AGR2, and KAI1 may represent potential metastatic and prognostic biomarkers, as well as promising therapeutic targets for HNSCC.

Pro-metastatic activity of AGR2 interrupts angiogenesis target bevacizumab efficiency via direct interaction with VEGFA and activation of NF-κB pathway

Anterior gradient 2 (AGR2), an endoplasmic reticulum (ER)-resident protein-disulfide isomerase (PDI), is associated with cancer development and malignant progression. Here, we show that high level of AGR2 promotes the aggressive phenotype of prostate cancer (PCa) mouse models developed by either patient-derived xenografts or surgical intra-prostate implantation of PCa cells, associated with enrichment of the blood vessel network in tumor tissues. Angiogenesis markers VEGFR2 and CD34, accompanied with the invasive marker Vimentin, were predominantly stained in metastatic liver tissues. Secreted AGR2 was defined to enhance VEGFR2 activity as evidenced by physical interaction of purified recombinant human AGR2 (rhAGR2) with rhVEGFA through the formation of a disulfide bond. Mutant or deleted thioredoxin motif in rhAGR2 was also unable to bind to rhVEGFA that led to the significant abolishment in the vessel formation, but partially affecting the aggressive process, implicating alternative mechanisms are required for AGR2-conferring metastasis. Cytosolic AGR2 contributed to cell metastasis ascribed to its stabilizing effect on p65 protein, which subsequently activated the NF-κB and facilitated epithelial to mesenchymal transition (EMT). Importantly, GSH and cabozantinib, but not bevacizumab, effectively blocked the pro-angiogenic effect of rhAGR2 in vitro and in vivo, providing evidence that secreted AGR2 acts as a predictive biomarker for selection of angiogenesis-targeting therapeutic drugs based on its levels in the circular system.

Inhibition of JAK2/STAT3 reduces tumor-induced angiogenesis and myeloid-derived suppressor cells in head and neck cancer

Angiogenesis is an essential event in tumor growth and metastasis, and immune system also contributes to the tumor evasion. Emerging evidences have suggested the bidirectional link between angiogenesis and immunosuppression. Myeloid-derived suppressor cell (MDSC) is a kind of immunosuppressive cells and plays an important role in this process. However, the actual regulatory mechanisms of angiogenesis and MDSCs in head and neck squamous cell carcinoma (HNSCC) were unclear. In this study, through analyzing the immunohistochemistry staining of human HNSCC tissue microarray, we found that the microvascular density (MVD) was significantly increased in HNSCC patients. We also characterized angiogenic factors p-STAT3, VEGFA, CK2, and MDSCs marker CD11b in HNSCC tissue array, and found the close expression correlation among these markers. To determine the role of JAK2/STAT3 pathway in tumor microenvironment of HNSCC, we utilized AG490 (an inhibitor of JAK2/STAT3) for further research. Results showed that inhibition of JAK2/STAT3 suppressed angiogenesis by decreasing VEGFA and HIF1-α both in vitro and vivo. Moreover, in HNSCC transgenic mouse model, inhibiting JAK2/STAT3 not only suppressed angiogenesis but also reduced MDSCs in the tumor microenvironment through suppressing VEGFA and CK2. Our findings demonstrated the close relationship between angiogenesis and MDSCs in HNSCC, and inhibition of JAK2/STAT3 could reduce tumor-induced angiogenesis and decrease MDSCs.

Hypoxia induces TFE3 expression in head and neck squamous cell carcinoma

To assess the role of transcription factor μE3 (TFE3) in the tumorigenesis of head and neck squamous cell carcinoma (HNSCC), human HNSCC tissue arrays were investigated for TFE3 expression. Human HNSCC tissues with neoadjuvant inductive chemotherapey (docetaxel, cisplatin and fluorouracil, TPF) and mice HNSCC tissues from transgenic mice model were evaluated for TFE3 expression and the hypoxia pathway. The roles of EGF/EGFR mediated hypoxia in TFE3 nuclear expression were analyzed in vitro and in vivo. TFE3 expression was higher in human HNSCC tissues compared with that in normal oral mucosa. Moreover, high TFE3 expression was related to HIF-1α, PAI-1, and EGFR, which demonstrated the activation of the hypoxia pathway in HNSCC tissues. Furthermore, elevated TFE3 expression was observed in HNSCC after cisplatin-based chemotherapy, and high TFE3 expression may indicate poor response to TPF inductive chemotherapy. Furthermore, similar changes with increased TFE3 were observed in HNSCC of the transgenic mouse HNSCC model. Hypoxic culture in the human HNSCC cell line increased TFE3 expression, which promoted cell survival under hypoxia. EGFR inhibiton by cetuximab could attenuate hypoxia-induced TFE3 in the HNSCC cell line and transgenic mouse HNSCC model. These findings indicated that TFE3 was an important hypoxia-induced transcriptional factor in HNSCC. TFE3 could be regarded as a durgable therapeutic oncotarget by EGFR inhibition.

TRAF6 regulates tumour metastasis through EMT and CSC phenotypes in head and neck squamous cell carcinoma

Epithelial–mesenchymal transition (EMT) is associated with metastasis formation, generation and maintenance of cancer stem cells (CSCs). However, the regulatory mechanisms of CSCs have not been clarified. This study aims to investigate the role of TNF receptor‐associated factor 6 (TRAF6) on EMT and CSC regulation in squamous cell carcinoma of head and neck (SCCHN). We found TRAF6 was overexpressed in human SCCHN tissues, and high TRAF6 expression was associated with lymphatic metastasis and resulted in poor prognosis in patients with SCCHN. In addition, elevated TRAF6 expression was observed in several HNSCC cell lines, and wound healing and transwell assay results showed that TRAF6 knockdown inhibited the migration and invasion ability of the SCCHN cells. Moreover, the expression of Vimentin, Slug and N‐cadherin was down‐regulated and that of E‐cadherin was elevated after TRAF6 knockdown but decreased by transforming growth factor beta 1 (TGF‐β1) and CAL27 similar to mesenchymal cells formed after TGF‐β1 induction. In addition, the expression levels of CD44, ALDH1, KLF4 and SOX2 were inhibited after TRAF6 knockdown, and the anchor‐dependent colony formation number and sphere number were remarkably reduced. Flow cytometry showed TRAF6 knockdown reduced ALDH1‐positive cancer stem cells. We also demonstrated that TRAF6 is closely associated with EMT process and cancer stem cells using a Tgfbr1/Pten 2cKO mice SCCHN model and human SCCHN tissue microarray. Our findings indicate that TRAF6 plays a role in EMT phenotypes, the generation and maintenance of CSCs in SCCHN, suggesting that TRAF6 is a potential therapeutic target for SCCHN.

Circulating tumour cells from patients with colorectal cancer have cancer stem cell hallmarks in ex vivo culture

OBJECTIVE

Although counting of circulating tumour cells (CTC) has attracted a broad interest as potential markers of tumour progression and treatment response, the lack of functional characterisation of these cells had become a bottleneck in taking these observations to the clinic. Our objective was to culture these cells in order to understand them and exploit their therapeutic potential to the full.

DESIGN

Here, hypothesising that some CTC potentially have cancer stem cell (CSC) phenotype, we generated several CTC lines from the blood of patients with advanced metastatic colorectal cancer (CRC) based on their self-renewal abilities. Multiple standard tests were then employed to characterise these cells.

RESULTS

Our CTC lines self-renew, express CSC markers and have multilineage differentiation ability, both in vitro and in vivo. Patient-derived CTC lines are tumorigenic in subcutaneous xenografts and are also able to colonise the liver after intrasplenic injection. RNA sequencing analyses strikingly demonstrate that drug metabolising pathways represent the most upregulated feature among CTC lines in comparison with primary CRC cells grown under similar conditions. This result is corroborated by the high resistance of the CTC lines to conventional cytotoxic compounds.

CONCLUSIONS

Taken together, our results directly demonstrate the existence of patient-derived colorectal CTCs that bear all the functional attributes of CSCs. The CTC culture model described here is simple and takes <1 month from blood collection to drug testing, therefore, routine clinical application could facilitate access to personalised medicine.

CLINICAL TRIAL REGISTRATION

ClinicalTrial.gov NCT01577511.

NLRP3 inflammasome activation promotes inflammation-induced carcinogenesis in head and neck squamous cell carcinoma

Background

NLRP3 inflammasome acts as a danger signal sensor that triggers and coordinates the inflammatory response. However, the roles of NLRP3 inflammasome in the tumorigenesis and development of cancer stem cells (CSCs) of squamous cell carcinoma of the head and neck (SCCHN) remain ambiguous.

Methods

In our study, tissue microarrays, ELISA, sphere-forming assay, colony formation assay and Western blot analysis were performed to evaluate the effect of NLRP3 inflammasome on the development of CSCs in human SCCHN tissue specimen, cell lines, and transgenic mouse SCCHN model.

Results

The components of NLRP3 inflammasome, namely, NLRP3, ASC, Caspase-1, and IL-18 were correlated with CSCs markers BMI1, ALDH1 and CD44 in human SCCHN specimens. Moreover, NLRP3, Caspase-1, IL-1β, and IL-18 were highly expressed in SCCHN cell lines. NLRP3 inflammasome activated by LPS and ATP promoted sphere-forming and colony formation capacities along with an upregulation of BMI1, ALDH1 and CD44. In addition, NLRP3 inflammasome blockade by NLRP3 inhibitor MCC950 reduced sphere and colony number, also decreased the expression of BMI1, ALDH1 and CD44 in SCCHN cell lines. Expression of NLRP3, ASC, Caspase-1, IL-1β, IL-18, BMI1, ALDH1 and CD44 was upregulated in Tgfbr1/Pten 2cKO mouse SCCHN model, and NLRP3 inflammasome expression was closely related to those CSCs makers in mice SCCHN. However, MCC950 treatment reduced the expression of NLRP3 inflammasome, CSCs markers BMI1, ALDH1 and CD44 in Tgfbr1/Pten 2cKO mice SCCHN. In addition, blockade of NLRP3 inflammasome can also delayed the tumor-burdened speed in SCCHN mice.

Conclusions

Our study demonstrates that NLRP3 inflammasome was upregulated and associated with the carcinogenesis and CSCs self-renewal activation in SCCHN. NLRP3 inflammasome can be a potential target in the development of novel approaches for head and neck squamous cell carcinoma therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0589-y) contains supplementary material, which is available to authorized users.

Targeting phosphorylation of STAT3 delays tumor growth in HPV-negative anal squamous cell carcinoma mouse model

Although conventional chemoradiotherapy is effective for most anal squamous cell carcinoma (ASCC) patients, HPV-negative ASCC patients respond poorly to this treatment and new therapeutic approach is required. Our group has previously established an HPV-negative ASCC mouse model and demonstrated that signal transducer and activation of transcription 3 (STAT3) is hyper-activated in the model. Here, we show that in vivo inhibition of STAT3 by S3I-201 effectively delays tumor growth in ASCC mouse model indicated by significantly smaller tumor size and burden in the treatment group compared with control group at the same point. Further analysis shows that survivin and Ki67, important biomarkers for tumor cell survival and proliferation, are significantly reduced after S3I-201 treatment. Additionally, flow cytometry and immunohistofluorescent assays reveal decreased Myeloid-derived suppressor cell (MDSC) and tumor-associated macrophage (TAM) populations in the S3I-201 treatment group, which indicates a reversion of the immunosuppressive environment, unraveling the potential role for S3I-201 in immunosuppression in ASCC. Together these results for the first time demonstrated the anti-tumor effects of STAT3 inhibitor S3I-201 in HPV-negative ASCC mouse model and its multiple effects on cancer cells and immune system. Thus we conclude that S3I-201 may be a novel therapeutic approach for HPV-negative ASCC patients.

Pleomorphism and drug resistant cancer stem cells are characteristic of aggressive primary meningioma cell lines

Background

Meningioma tumors arise in arachnoid membranes, and are the most reported central nervous system (CNS) tumors worldwide. Up to 20% of grade I meningioma tumors reoccur and currently predictive cancer stem cells (CSCs) markers for aggressive and drug resistant meningiomas are scarce.

Methods

Meningioma tissues and primary cell lines were investigated using whole transcriptome microarray analysis, immunofluorescence staining of CSCs markers (including CD133, Sox2, Nestin, and Frizzled 9), and drug treatment with cisplatin or etoposide.

Results

Unsupervised hierarchical clustering of six meningioma samples separated tissues into two groups. Analysis identified stem cells related pathways to be differential between the two groups and indicated the de-regulation of the stem cell associated genes Reelin (RELN), Calbindin 1 (CALB1) and Anterior Gradient 2 Homolog (AGR2). Immunofluorescence staining for four tissues confirmed stemness variation in situ. Biological characterization of fifteen meningioma primary cell lines concordantly separated cells into two functionally distinct sub-groups. Pleomorphic cell lines (NG type) grew significantly faster than monomorphic cell lines (G type), had a higher number of cells that express Ki67, and were able to migrate aggressively in vitro. In addition, NG type cell lines had a lower expression of nuclear Caspase-3, and had a significantly higher number of CSCs co-positive for CD133+ Sox2+ or AGR2+ BMI1+. Importantly, these cells were more tolerant to cisplatin and etoposide treatment, showed a lower level of nuclear Caspase-3 in treated cells and harbored drug resistant CSCs.

Conclusion

Collectively, analyses of tissues and primary cell lines revealed stem cell associated genes as potential targets for aggressive and drug resistant meningiomas.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0441-7) contains supplementary material, which is available to authorized users.

SOX2 Drives Bronchial Dysplasia in a Novel Organotypic Model of Early Human Squamous Lung Cancer

RATIONALE

Improving the early detection and chemoprevention of lung cancer are key to improving outcomes. The pathobiology of early squamous lung cancer is poorly understood. We have shown that amplification of sex-determining region Y-box 2 (SOX2) is an early and consistent event in the pathogenesis of this disease, but its functional oncogenic potential remains uncertain. We tested the impact of deregulated SOX2 expression in a novel organotypic system that recreates the molecular and microenvironmental context in which squamous carcinogenesis occurs.

OBJECTIVES

(1) To develop an in vitro model of bronchial dysplasia that recapitulates key molecular and phenotypic characteristics of the human disease; (2) to test the hypothesis that SOX2 deregulation is a key early event in the pathogenesis of bronchial dysplasia; and (3) to use the model for studies on pathogenesis and chemoprevention.

METHODS

We engineered the inducible activation of oncogenes in immortalized bronchial epithelial cells. We used three-dimensional tissue culture to build an organotypic model of bronchial dysplasia.

MEASUREMENTS AND MAIN RESULTS

We recapitulated human bronchial dysplasia in vitro. SOX2 deregulation drives dysplasia, and loss of tumor promoter 53 is a cooperating genetic event that potentiates the dysplastic phenotype. Deregulated SOX2 alters critical genes implicated in hallmarks of cancer progression. Targeted inhibition of AKT prevents the initiation of the dysplastic phenotype.

CONCLUSIONS

In the appropriate genetic and microenvironmental context, acute deregulation of SOX2 drives bronchial dysplasia. This confirms its oncogenic potential in human cells and affords novel insights into the impact of SOX2 deregulation. This model can be used to test therapeutic agents aimed at chemoprevention.

DKK3 Overexpression Increases the Malignant Properties of Head and Neck Squamous Cell Carcinoma Cells

DKK3, a member of the dickkopf Wnt signaling pathway inhibitor family, is believed to be a tumor suppressor because of its reduced expression in cancer cells. However, our previous studies have revealed that DKK3 expression is predominantly observed in head and neck/oral squamous cell carcinoma (HNSCC/OSCC). Interestingly, HNSCC/OSCC patients with DKK3 expression showed a high rate of metastasis and poorer survival, and siRNA-mediated knockdown of DKK3 in HNSCC-derived cancer cell lines resulted in reduced cellular migration and invasion. From these data, it was hypothesized that DKK3 might exert an oncogenic function specific to HNSCC. In the present research, the DKK3 overexpression model was established, and its influences were investigated, together with molecular mechanism studies. The DKK3 expression profile in cancer cell lines was investigated, including HNSCC/OSCC, esophageal, gastric, colorectal, pancreatic, prostatic, and lung cancers. DKK3 overexpression was performed in HNSCC-derived cells by transfection of expression plasmid. The effects of DKK3 overexpression were assessed on cellular proliferation, migration, invasion, and in vivo tumor growth. The molecular mechanism of DKK3 overexpression was investigated by Western blotting and microarray analysis. DKK3 overexpression significantly elevated cellular proliferation, migration, and invasion, as well as increased mRNA expression of cyclin D1 and c-myc. However, reporter assays did not show TCF/LEF activation, suggesting that the increased malignant property of cancer cells was not driven by the Wnt/β-catenin pathway. For the investigation of the pathways/molecules in DKK3-mediated signals, the Western blot analyses revealed that phosphorylation of Akt (S473) and c-Jun (Ser63) was elevated. The application of a PI3K kinase inhibitor, LY294002, on HSC-3 DKK3 cells significantly decreased tumor cell proliferation, migration, and invasion. From these results, we demonstrated that DKK3 might contribute to cellular proliferation, invasion, migration, and tumor cell survival in HNSCC cells through a mechanism other than the canonical Wnt signaling pathway, which might be attributed to PI3K–Akt signaling.

Expression of VISTA correlated with immunosuppression and synergized with CD8 to predict survival in human oral squamous cell carcinoma

V-domain Ig suppressor of T cell activation (VISTA), a novel immune checkpoint regulatory molecule, suppresses T cell mediated immune responses. The aim of the present study was to profile the immunological expression, clinical significance and correlation of VISTA in human oral squamous cell carcinoma (OSCC). Human tissue microarrays, containing 165 primary OSCCs, 48 oral epithelial dysplasias and 43 normal oral mucosae, were applied to investigate the expression levels of VISTA, CD8, cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), programmed death ligand 1 (PD-L1), PI3Kα p110, IL13Rα2, phospho-STAT3 at tyrosine 705 (p-STAT3) and myeloid-derived suppressor cell (MDSC) markers (CD11b and CD33) by immunohistochemistry and digital pathology analysis. The results demonstrated that the protein level of VISTA was significantly higher in human OSCC specimens, and that VISTA expression in primary OSCCs was correlated with lymph node status. VISTA expression did not serve as an independent predictor for poor prognosis, while patient subgroup with VISTA high and CD8 low expression (22/165) had significantly poorer overall survival compared with other subgroups based on the multivariate and Cox hazard analyses among the primary OSCC patients in the present cohort. Additionally, the expression of VISTA was significantly correlated with PD-L1, CTLA-4, IL13Rα2, PI3K, p-STAT3, CD11b and CD33 according to Pearson's correlation coefficient test. Taken together, the results indicated that the VISTA high and CD8 low group, as an immunosuppressive subgroup, might be associated with a poor prognosis in primary OSCC. These findings indicated that VISTA might be a potential immunotherapeutic target in OSCC treatment.

HoxB9 promotes the migration and invasion via TGF-β1/Smad2/Slug signaling pathway in oral squamous cell carcinoma

HoxB9, as a HOX family member, is known to play important roles in embryonic development. Recent studies have shown that HoxB9 is involved in cancer progression. However, little is known about the role of HoxB9 and the underlying mechanisms that suppress oral squamous cell carcinoma (OSCC) progression. In the present study, we used immunohistochemical staining to demonstrate that HoxB9 is over-expressed in OSCC cells and found that high levels of HoxB9 were significantly associated with shorter overall survival in patients with OSCC. Functional studies revealed that knocking down HoxB9 in OSCC cells using RNA interference decreased the migration and invasion of OSCC cells in vitro. Our mechanistic studies suggested that HoxB9 could stimulate the migration and invasion of OSCC cells by targeting EMT via the TGF-β1/Smad2/Slug signaling pathway. Collectively, these findings suggest the vital roles of HoxB9 in OSCC progression through its effects in promoting EMT.

AGR2 promotes the proliferation, migration and regulates epithelial-mesenchymal transition in salivary adenoid cystic carcinoma

Salivary adenoid cystic carcinoma (AdCC) is a common head and neck cancer with the propensity for local spread and distant metastasis. In our previous study, elevated expression of Anterior gradient 2 (AGR2) was detected in head and neck squamous cell carcinoma (HNSCC), associated with epithelial-mesenchymal transition (EMT) and cancer stemness. However, to date, the expression and function of AGR2 in AdCC has yet to be elucidated. In the present study, human AdCC tissue microarrays including 18 cases of normal salivary gland (NSG), 12 cases of pleomorphic adenoma (PMA) and 72 cases of AdCC were employed for immunohistochemical staining analysis. Results indicated that AGR2, which was remarkably correlated with Ki-67, transforming growth factor beta-1 (TGF-β1) and CD147, was significantly elevated in human salivary AdCC tissues. Knockdown of AGR2 significantly repressed the proliferation and migration of human SACC-83 and SACC-LM cell lines. Additionally, AGR2 silencing obviously reversed the EMT phenomena induced by TGF-β1. Taken together, our present study revealed the potential pro-metastasis role of AGR2 in AdCC, indicating that AGR2 might be a novel therapeutic target of AdCC with distant metastasis.

ER stress protein AGR2 precedes and is involved in the regulation of pancreatic cancer initiation

The mechanisms of initiation of pancreatic ductal adenocarcinoma (PDAC) are still largely unknown. In the present study, we analysed the role of anterior gradient-2 (AGR2) in the earliest stages of pancreatic neoplasia. Immunohistochemical analysis of chronic pancreatitis (CP) and peritumoral areas in PDAC tissues showed that AGR2 was present in tubular complexes (TC) and early pancreatic intraepithelial neoplasia (PanINs). Moreover, AGR2 was also found in discrete subpopulations of non-transformed cells neighbouring these pre-neoplastic lesions. In primary cells derived from human patient-derived xenograft (PDX) model, flow-cytometry revealed that AGR2 was overexpressed in pancreatic cancer stem cells (CSC) compared with non-stem cancer cells. In LSL-Kras^G12D;Pdx1-Cre (KC) mouse model Agr2 induction preceded the formation of pre-neoplastic lesions and their development was largely inhibited by Agr2 deletion in engineered LSL-Kras^G12D;Pdx1-Cre; Agr2^−/− mice. In vitro, AGR2 expression was stimulated by tunicamycin-induced endoplasmic reticulum (ER) stress in both KRAS wild-type normal pancreas cells, as well as in KRAS mutated pancreatic cancer cells and was essential for ER homoeostasis. The unfolded protein response proteins GRP78, ATF6 and XBP1s were found expressed in CP and PDAC peritumoral tissues, but in contrast to AGR2, their expression was switched off during TC and PanIN formation. Real-time PCR and ELISA analyses showed that ER stress induced a pro-inflammatory phenotype in pancreatic normal, cancer and stellate cells. Moreover, AGR2 expression was inducible by paracrine transfer of ER stress and pro-inflammation between different pancreatic cell types. Our findings demonstrate that AGR2 induced in ER-stressed and inflammatory pre-neoplastic pancreas is a potential marker of cancer progenitor cells with an important functional role in PDAC initiation.

SATB1 promotes tumor metastasis and invasiveness in oral squamous cell carcinoma

OBJECTIVE

Our aim is to evaluate the expression of SATB1 in human oral squamous cell carcinomas (OSCC) and its role in the invasiveness and metastasis of OSCC.

SUBJECTS AND METHODS

A human OSCC tissue microarray was used to evaluate the expression pattern of SATB1. SATB1 mRNA knockdown was performed in human OSCC cell lines SCC25 and Cal27 to assess the function of SATB1 in the invasiveness and metastasis of OSCC.

RESULTS

SATB1 is highly expressed in human OSCC determined by immunohistochemistry, and its nuclear/cytoplasmic ratio of histoscore is significantly correlated with patients' prognosis. Reduced cell motility, invasiveness, expression of epithelial to mesenchymal transition (EMT) markers (N-cadherin and β-catenin), and elevated expression of epithelial markers were observed in SATB1-knockdown cells in in vitro studies. Depletion of SATB1 also restored a cobblestone-like morphology in TGF-β1-treated cells.

CONCLUSIONS

These findings suggest SATB1 may play an important role in OSCC invasiveness and metastasis.

Implications of cancer stem cells in developing therapeutic resistance in oral cancer

Conventional therapeutics are often frequented with recurrences, refraction and regimen resistance in oral cavity cancers which are predominantly manifested by cancer stem cells (CSCs). During oncoevolution, cancer cells may undergo structural and functional reprogramming wherein they evolve as highly tolerant CSC phenotypes with greater survival advantages. The CSCs possess inherent and exclusive properties including self-renewal, hierarchical differentiation, and tumorigenicity that serve as the basis of chemo-radio-resistance in oral cancer. However, the key mechanisms underlying the CSC-mediated therapy resistance need to be further elucidated. A spectrum of dysfunctional cellular pathways including the developmental signaling, apoptosis, autophagy, cell cycle regulation, DNA damage responses and epigenetic regulations protect the CSCs from conventional therapies. Moreover, tumor niche shelters CSCs and creates an immunosuppressive environment favoring the survival of CSCs. Maintenance of lower redox status, epithelial-to-mesenchymal transition (EMT), metabolic reprogramming and altered drug responses are the accessory features that aid in the process of chemo-radio-resistance in oral CSCs. This review deals with the functional and molecular basis of cancer cell pluripotency-associated resistance highlighting the abrupt fundamental cellular processes; targeting these events may hold a great promise in the successful treatment of oral cancer.

Tumor growth suppression by inhibiting both autophagy and STAT3 signaling in HNSCC

Autophagy is considered as a double-edged sword. It can prolong the survival of cancer cells and enhance its resistance to apoptosis, and paradoxically, defective autophagy has been linked to increased tumorigenesis, but the mechanism behind this phenomenon is unclear. In this study, we demonstrated that decreased phosphorylation of signal transducer and activator of transcription 3 (p-STAT3) was correlated with increased autophagy through the Akt/mTOR and Erk signaling pathways in human head and neck squamous cell carcinoma (HNSCC). We also showed that blockage of STAT3 by NSC74859 could markedly induce apoptotic cell death and autophagy. Meanwhile, increased autophagy inhibited apoptosis. The pharmacological or genetic inhibition of autophagy and STAT3 further sensitized HNSCC cells to apoptosis. Furthermore, evidence from xenograft model proved that suppressed STAT3 activity combined with inhibition of autophagy promoted tumor regression better than either treatment alone. Taken together, this present study demonstrated that autophagy alleviates apoptotic cell death in HNSCC, and combination of inhibition of STAT3 by NSC74859 and autophagy might be a promising new therapeutic strategy for HNSCC.

STAT3 blockade enhances the efficacy of conventional chemotherapeutic agents by eradicating head neck stemloid cancer cell

Signaling transducer and activator 3 (STAT3) and cancer stem cells (CSCs) have garnered huge attention as a therapeutic focus, based on evidence that they may represent an etiologic root of tumor initiation and radio-chemoresistance. Here, we investigated the high phosphorylation status of STAT3 (p-STAT3) and its correlation with self-renewal markers in head neck squamous cell carcinoma (HNSCC). Over-expression of p-STAT3 was found to have increased in post chemotherapy HNSCC tissue. We showed that blockade of p-STAT3 eliminated both bulk tumor and side population (SP) cells with characteristics of CSCs in vitro. Inhibition of p-STAT3 using small molecule S3I-201 significantly delayed tumorigenesis of spontaneous HNSCC in mice. Combining blockade of p-STAT3 with cytotoxic drugs cisplatin, docetaxel, 5-fluorouracil (TPF) enhanced the antitumor effect in vitro and in vivo with decreased tumor sphere formation and SP cells. Taken together, our results advocate blockade of p-STAT3 in combination with conventional chemotherapeutic drugs enhance efficacy by improving CSCs eradication in HNSCC.

B7-H4 expression indicates poor prognosis of oral squamous cell carcinoma

Checkpoint blockade therapy utilizing monoclonal antibodies to reactivate T cells and recover their antitumor activity makes an epoch in cancer immunotherapy. The role of B7-H4, a novel negative immune checkpoint, in oral squamous cell carcinoma (OSCC) has still not been elucidated. In this study, tissue samples from human OSCC, which contains 165 primary OSCC, 48 oral epithelial dysplasia and 43 normal oral mucosa specimens, and Tgfbr1/Pten 2cKO mice OSCC model were stained with B7-H4 antibody to analyze the correlations between B7-H4 expression and clinicopathological characteristics. Kaplan-Meier analysis was used to compare the survival of patients with high B7-H4 expression and patients with low B7-H4 expression. We found B7-H4 is highly expressed in human OSCC tissue, and the B7-H4 expression level was associated with the clinicopathological parameters containing pathological grade and lymph node status. Moreover, we confirmed that B7-H4 was overexpressed in Tgfbr1/Pten 2cKO mice OSCC model. Our data also indicated that patients with high B7-H4 expression had poor overall survival compared with those with low B7-H4 expression. Furthermore, this study demonstrated that B7-H4 was positively associated with PD-L1, CD11b, CD33, PI3Kα p110, and p-S6 (S235/236). Taken together, these findings suggest B7-H4 is a potential target in the treatment of OSCC.

PAK2 promotes migration and proliferation of salivary gland adenoid cystic carcinoma

P21 activated kinase 2 (PAK2) is a member of Group I PAKs family and highly expressed in various cancers. Current studies have demonstrated that PAK2 played a pivotal role in tumor progression. However, the role of PAK2 in salivary adenoid cystic carcinoma is still unclear. This study aims to explore the expression and the function of PAK2 in AdCC. Human salivary gland tissue microarray, including 18 normal salivary glands (NSG), 12 pleomorphic adenoma (PMA) and 72 AdCC, and immunohistochemistry were used to evaluate the expression of PAK2. The result showed that PAK2 was significantly increased in AdCC compared with NSG and PMA. Then the Pearson correlation analysis using serial tissue sections showed a close correlation of PAK2 with Cyclin D1, Phospho-STAT3 at Tyrosine 705 (p-STAT3) and Ki-67. Further in vitro study utilizing PAK2 knockdown via siRNA transfection revealed significantly reduced migration and proliferation of AdCC cell lines compared with control group. Knockdown of PAK2 decreased the expression of Cyclin D1 in AdCC cell lines. In addition, the inhibition of STAT3 reduced the expression of PAK2 in AdCC cell lines. These findings suggested that PAK2 promotes AdCC cell migration and proliferation and may be a potential therapeutic target.

Investigation of the association between miR‑181b, Bcl‑2 and LRIG1 in oral verrucous carcinoma

Abnormal expression of microRNAs (miRNAs) is involved in the development of and anti-apoptotic effects in various types of human cancer. However, miRNA-mediated regulation of oral verrucous carcinoma (OVC) remains to be elucidated. The present study aimed to investigate the expression of miR-181b in OVC and oral squamous cell carcinoma (OSCC). The expression levels of miR-181b were determined using reverse transcription-quantitative polymerase chain reaction. The expression levels of B-cell lymphoma 2 (Bcl-2) and leucine rich repeats and immunoglobulin like domains 1 (LRIG1), were evaluated using immunohistochemical staining. The correlation between Bcl-2 and LRIG1 expression was determined using a Pearson correlation analysis. The expression levels of miR-181b and Bcl-2 in OVC were significantly higher compared with normal mucosal tissue (NM); however, lower compared with the OSCC. The key target of miR-181b was LRIG1 and it was significantly lower in OVC tissues compared with NM tissue; however this was higher when compared with OSCC tissue. The expression levels of Bcl-2 were correlated with expression levels of LRIG1 in OVC tissues. Therefore, LRIG1 may be associated with anti-apoptotic function in OVC tissues.

Secretion of protein disulphide isomerase AGR2 confers tumorigenic properties

The extracellular matrix (ECM) plays an instrumental role in determining the spatial orientation of epithelial polarity and the formation of lumens in glandular tissues during morphogenesis. Here, we show that the Endoplasmic Reticulum (ER)-resident protein anterior gradient-2 (AGR2), a soluble protein-disulfide isomerase involved in ER protein folding and quality control, is secreted and interacts with the ECM. Extracellular AGR2 (eAGR2) is a microenvironmental regulator of epithelial tissue architecture, which plays a role in the preneoplastic phenotype and contributes to epithelial tumorigenicity. Indeed, eAGR2, is secreted as a functionally active protein independently of its thioredoxin-like domain (CXXS) and of its ER-retention domain (KTEL), and is sufficient, by itself, to promote the acquisition of invasive and metastatic features. Therefore, we conclude that eAGR2 plays an extracellular role independent of its ER function and we elucidate this gain-of-function as a novel and unexpected critical ECM microenvironmental pro-oncogenic regulator of epithelial morphogenesis and tumorigenesis.

DOI:http://dx.doi.org/10.7554/eLife.13887.001

Cancer cells multiply abnormally fast and therefore produce protein molecules faster than normal cells. To avoid becoming stressed by this overproduction, cancer cells make use of proteins that fold the new proteins inside the cell. One of these protein folders is called anterior gradient-2 (or AGR2 for short) and is produced at high levels in so-called epithelial cancers, such as breast and lung cancer.

Previous research has shown that AGR2 inside cancer cells can help them grow and survive and AGR2 can also be found outside cells, such as in the blood or the urine of cancer patients. Therefore some researchers have suggested that measuring the levels of AGR2 in bodily fluids may be a useful marker for detecting cancers. Fessart et al. hypothesized that – apart from becoming a promising diagnostic tool – the AGR2 protein itself, specifically when found outside cells, might make cancer cells more aggressive.

Fessart et al. used a range of techniques to test this hypothesis. For example, healthy lung cells and lung cancer cells were grown into miniature replicas of lung organs in the laboratory, and in a key experiment, AGR2 was added to the lung organoids grown from the healthy cells. The addition of AGR2 protein was enough to change the non-tumor organoids into tumor organoids and boosted their growth about ten-fold. Further experiments then revealed that AGR2 also makes cells more invasive and capable of moving, both important features of aggressive cancer cells.

Overall, Fessart et al. have proven that AGR2 is a signalling molecule found outside cancer cells that makes them more aggressive. In future, more research addressing how AGR2 achieves this may lead to new therapeutic strategies against some forms of cancer.

DOI:http://dx.doi.org/10.7554/eLife.13887.002

NOTCH1 inhibition enhances the efficacy of conventional chemotherapeutic agents by targeting head neck cancer stem cell

Cancer stem cells (CSCs) are considered responsible for tumor initiation and chemoresistance. This study was aimed to investigate the possibility of targeting head neck squamous cell carcinoma (HNSCC) by NOTCH1 pathway inhibition and explore the synergistic effect of combining NOTCH inhibition with conventional chemotherapy. NOTCH1/HES1 elevation was found in human HNSCC, especially in tissue post chemotherapy and lymph node metastasis, which is correlated with CSCs markers. NOTCH1 inhibitor DAPT (GSI-IX) significantly reduces CSCs population and tumor self-renewal ability in vitro and in vivo. Flow cytometry analysis showed that NOTCH1 inhibition reduces CSCs frequency either alone or in combination with chemotherapeutic agents, namely, cisplatin, docetaxel, and 5-fluorouracil. The combined strategy of NOTCH1 blockade and chemotherapy synergistically attenuated chemotherapy-enriched CSC population, promising a potential therapeutic exploitation in future clinical trial.

FOXA1 expression affects the proliferation activity of luminal breast cancer stem cell populations

The expression of estrogen receptor is the key in most breast cancers (BC) and binding of estrogen receptor to the genome correlates to Forkhead protein (FOXA1) expression. We herein assessed the correlation between the cancer stem cell (CSC) population and FOXA1 expression in luminal BC. We established luminal BC cells derived from metastatic pleural effusion and analyzed the potency of CSC and related factors with established luminal BC cell lines. We also confirmed that mammosphere cultures have an increased aldehyde dehydrogenase‐positive population, which is one of the CSC markers, compared with adherent culture cells. Using a quantitative PCR analysis, we found that mammosphere forming cells showed a higher expression of FOXA1 and stemness‐related genes compared with adherent culture cells. Furthermore, the growth activity and colony‐forming activity of 4‐hydroxytamoxifen‐treated BC cells were inhibited in a mammosphere assay. Interestingly, 4‐hydroxytamoxifen‐resistant cells had significantly increased FOXA1 gene expression levels. Finally, we established short hairpin RNA of FOXA1 (shFOXA1) MCF‐7 cells and investigated the relationship between self‐renewal potential and FOXA1 expression. As a result, we found no significant difference in the number of mammospheres but decreased colony formation in shFOXA1 MCF‐7 cells compared with control. These results suggest that the expression of FOXA1 appears to be involved in the proliferation of immature BC cells rather than the induction of stemness‐related genes and self‐renewal potency of CSCs.

C4.4A as a biomarker of head and neck squamous cell carcinoma and correlated with epithelial mesenchymal transition

C4.4A, a member of the Ly6/uPAR family of membrane proteins, has been identified as a metastasis-associated molecule, but little is known about its actual expression and possible function in head and neck squamous cell carcinoma (HNSCC). To explore diagnostic and prognostic roles of C4.4A in HNSCC, we investigated the expression of C4.4A in human HNSCC tissue array which contains 43 HNSCC, 6 epithelial dysplasia and 16 normal oral mucosa. Expression of C4.4A was significantly increased in epithelial dysplasia and HNSCC when compared with normal oral mucosa. Moreover, high C4.4A expression indicated a rather poor prognosis of HNSCC patients. To better understand the function of C4.4A in HNSCC progression, we investigated epithelial to mesenchymal transition (EMT) associated proteins including transforming growth factor (TGF-β1), Slug and CD147 in HNSCC. The expression of TGF-β1, Slug, and CD147 was significantly increased in HNSCC when compared with normal oral mucosa. Meanwhile, the expression of C4.4A was significantly correlated with TGF-β1, Slug, and CD147 in HNSCC tissue array. Furthermore, knockdown of C4.4A decreased the cell invasion and migration in CAL27 cell line and suppressed the EMT with increased E-cadherin and decreased N-cadherin and Slug. Our study demonstrated that C4.4A was a potential marker for prognosis of HNSCC, and C4.4A participated in EMT program in HNSCC progression.