Loss of heterozygosity on chromosome 6q correlates with decreased thrombospondin-2 expression in human salivary gland carcinomas

Serum thrombospondin 2 is a novel predictor for the severity in the patients with NAFLD

AIM

Thrombospondins are a family of multidomain and secretory glycoproteins. Among them, thrombospondin 2 (TSP2) encoded by TSP2 gene has been reported to be involved in various functions such as collagen/fibrin formation, maintenance of normal blood vessel density and cell adhesion properties. Microarray analyses ranked TSP2 as one of the most highly up-regulated genes in the fibrotic liver in patients with non-alcoholic fatty liver disease (NAFLD). Since TSP2 possesses unique properties as a secretory protein, we hypothesized that hepatic TSP2 gene expression levels would be reflected in serum TSP2 levels. In this study, we examined the relationship between serum TSP2 concentrations and clinicopathological findings in NAFLD patients.

METHODS

One hundred and thirty NAFLD patients who had undergone liver biopsy between 2009 and 2015 were retrospectively enrolled. Serum samples were collected at the time of biopsy, and TSP2 was measured by enzyme immunoassays.

RESULTS

Serum TSP2 levels moderately correlated with ballooning (r = 0.56, P < .001) and fibrosis stage (r = 0.53, P < .001). The AUC values of TSP2 for predicting mild fibrosis (≧F1), moderate fibrosis (≧F2) and severe fibrosis (≧F3) were 0.73, 0.76 and 0.82 respectively. Additionally, NAFLD activity score (NAS) correlated best with TSP2 (r = 0.52, P < .001) compared to conventional NAFLD-related biomarkers, such as cytokeratin 18 M30, hyaluronic acid, type IV collagen 7S, APRI and FIB-4 index.

CONCLUSION

Serum TSP2 levels reflected hepatocyte ballooning, fibrosis and NAS in NAFLD patients. For clinical application of serum TSP2 as a predictor of NAFLD histological activity, additional validation and mechanistic investigations are required.

Shallow whole genome sequencing of adenoid cystic carcinomas of the salivary glands identifies specific chromosomal aberrations related to tumor progression

BACKGROUND AND PURPOSE

Adenoid cystic carcinomas (ACC) are characterized by high rate of local recurrence and late distant metastasis. Chromosomal changes in the evolution from primary tumors to metastatic disease of ACC have not been appointed. Here we investigated the chromosomal alterations of 53 primary tumors from ACC patients with different progressive states by shallow whole genome sequencing to identify potential new markers for metastatic spread.

METHODS

Illumina paired-end libraries were generated using DNA from the primary tumor of 53 ACC patients. Fragmented DNA was end-repaired, A-tailed and multiplex sequencing adapters were ligated. Sequence data were mapped to HG19 and a copy-number analysis was conducted using the QDNAseq R package (version 1.10.0). Outliers were removed and data was smoothed by applying the circular binary segmentation algorithm implemented in the R package copynumber version 1.22.0. A modified chromosomal instability (CNI) score was used to analyze deletions and amplifications.

RESULTS

Cluster analysis of the whole genome sequencing revealed that the frequency of chromosomal aberrations were increased in ACC with local recurrence and distant metastases in comparison to ACC patients with no metastatic spread. Specifically, chromosome 6 and 12 and exclusively the entire chromosome 4 showed an increased frequency of chromosomal alterations with tumor progression.

CONCLUSION

Our data show a molecular evolution from primary tumors to local recurrences and distant metastases and pinpoint the critical chromosomal regions involved in this process. These regions should be in the focus of the search for therapeutic targets of progressive ACC.

Downregulation of microRNA-1246 inhibits tumor growth and promotes apoptosis of cervical cancer cells by targeting thrombospondin-2

Cervical cancer pathogenesis is regulated by numerous factors, including microRNAs. MicroRNA 1246 (miR-1246) has been shown to serve a role in cervical cancer tumorigenesis. However, the mechanisms through which miR-1246 exerts its oncogenic effects are largely unknown. The aim of the current study was to evaluate the effects of lentivirus-mediated miR-1246 knockdown on the biological characteristics and behavior of cervical cancer cells, and to identify the downstream signaling pathways affected by miR-1246 knockdown. Short hairpins inhibiting miR-1246 were synthesized and cloned into a recombinant lentiviral vector (LV-miR-1246-Inh), which was then used to infect SiHa cervical cancer cells. The effects of LV-miR-1246-Inh infection on cell invasion, proliferation and apoptosis were evaluated by Transwell assay, Cell Counting Kit-8 assay and flow cytometry, respectively. Thrombospondin-2 (THBS2), matrix metalloproteinase 2 (MMP2), MMP9 and extracellular matrix (ECM) component expression levels were evaluated, and the growth of xenograft tumors formed following injection of SiHa cells with knockdown of miR-1246 was assessed. miR-1246 downregulation in SiHa cells decreased proliferation, induced apoptosis and upregulated THBS2 expression. Furthermore, MMP2 and MMP9 levels were downregulated, whereas components of the ECM were upregulated subsequent to miR-1246 knockdown, indicating that this miRNA regulates cervical cancer cell pathogenesis via the THBS2/MMP/ECM pathway. Notably, SiHa cells with miR-1246 downregulation had a markedly decreased ability to form tumors in vivo. These results suggest that miR-1246 functions during cervical cancer pathogenesis and tumor formation via the THBS2/MMP/ECM signaling pathway. These findings support the future use of miR-1246 suppression in the treatment of cervical cancer.

Nodal metastasis and survival in oral cancer: Association with protein expression of SLPI, not with LCN2, TACSTD2, or THBS2

BACKGROUND

Gene expression profiling revealed a strong signature predicting lymph node metastases in oral squamous cell carcinoma (OSCC). Four of the most predictive genes are secretory leukocyte protease inhibitor (SLPI), lipocalin-2 (LCN2), thrombospondin-2 (THBS2), and tumor-associated calcium signal transducer 2 (TACSTD2). This study correlates their protein expression with lymph node metastases, overall survival (OS), and disease-specific survival (DSS).

METHODS

Two hundred twelve patients with OSCC were included for protein expression analysis by immunohistochemistry.

RESULTS

SLPI expression correlates with lymph node metastases in the whole cohort, not in a subgroup of cT1 to 2N0. SLPI expression correlates with OS (hazard ratio [HR] = 0.61) and DSS (HR = 0.47) in multivariate analysis. LCN2, THBS2, and TACSTD2 show no correlation with lymph node metastases, OS, or DSS.

CONCLUSION

Although SLPI expression correlates with lymph node metastases, it has no additional value in determining lymph node metastases in early oral cancer. However, it is an independent predictor for both OS and DSS and therefore a relevant prognostic biomarker in OSCC.

Genetic profile of adenoid cystic carcinomas (ACC) with high-grade transformation versus solid type

BACKGROUND

ACC can occasionally undergo dedifferentiation also referred to as high-grade transformation (ACC-HGT). However, ACC-HGT can also undergo transformation to adenocarcinomas which are not poorly differentiated. ACC-HGT is generally considered to be an aggressive variant of ACC, even more than solid ACC. This study was aimed to describe the genetic changes of ACC-HGT in relation to clinico-pathological features, and to compare results to solid ACC.

METHODS

Genome wide DNA copy number changes were analyzed by microarray CGH in ACC-HGT, four with transformation into moderately differentiated adenocarcinoma (MDA) and two into poorly differentiated carcinoma (PDC), and five solid ACC. In addition, Ki67 index and p53 immunopositivity was assessed.

RESULTS

ACC-HGT carried fewer copy number changes compared to solid ACC. Two ACC-HGT cases harboured a breakpoint at 6q23, near the cMYB oncogene. The complexity of the genomic profile concurred with the clinical course of the patient. Among the ACC-HGT, p53 positivity significantly increased from the conventional to the transformed (both MDA and PDC) component.

CONCLUSION

ACC-HGT may not necessarily reflect a more advanced stage of tumor progression, but rather a transformation to another histological form in which the poorly differentiated forms (PDC) presents a genetic complexity similar to the solid ACC.

Comprehensive analysis of the MYB-NFIB gene fusion in salivary adenoid cystic carcinoma: Incidence, variability, and clinicopathologic significance

PURPOSE

The objectives of this study were to determine the incidence of the MYB-NFIB fusion in salivary adenoid cystic carcinoma (ACC), to establish the clinicopathologic significance of the fusion, and to analyze the expression of MYB in ACCs in the context of the MYB-NFIB fusion.

EXPERIMENTAL DESIGN

We did an extensive analysis involving 123 cancers of the salivary gland, including primary and metastatic ACCs, and non-ACC salivary carcinomas. MYB-NFIB fusions were identified by reverse transcriptase-PCR (RT-PCR) and sequencing of the RT-PCR products, and confirmed by fluorescence in situ hybridization. MYB RNA expression was determined by quantitative RT-PCR and protein expression was analyzed by immunohistochemistry.

RESULTS

The MYB-NFIB fusion was detected in 28% primary and 35% metastatic ACCs, but not in any of the non-ACC salivary carcinomas analyzed. Different exons in both the MYB and NFIB genes were involved in the fusions, resulting in expression of multiple chimeric variants. Notably, MYB was overexpressed in the vast majority of the ACCs, although MYB expression was significantly higher in tumors carrying the MYB-NFIB fusion. The presence of the MYB-NFIB fusion was significantly associated (P = 0.03) with patients older than 50 years of age. No correlation with other clinicopathologic markers, factors, and survival was found.

CONCLUSIONS

We conclude that the MYB-NFIB fusion characterizes a subset of ACCs and contributes to MYB overexpression. Additional mechanisms may be involved in MYB overexpression in ACCs lacking the MYB-NFIB fusion. These findings suggest that MYB may be a specific novel target for tumor intervention in patients with ACC.

Potential relevance of bell-shaped and u-shaped dose-responses for the therapeutic targeting of angiogenesis in cancer

Tumor angiogenesis, the growth of new blood vessels into tumors, facilitates tumor growth and thus represents an attractive therapeutic target. Numerous experimental angiogenesis inhibitors have been characterised and subsequently trialled in patients. Some of these agents have failed to show any substantial activity in patients. In contrast, others have been more successful, but even these provide only a few months extra patient survival. Recent work has focused on understanding the effects of anti-angiogenic agents on tumor biology and has revealed a number of new findings that may help to explain the limited efficacy of angiogenesis inhibitors. Herein, I review the evidence that hormetic dose-responses (i.e. bell-shaped and U-shaped dose-response curves) are often observed with anti-angiogenic agents. Agents reported to exhibit these types of dose-response include: 5-fluorouracil, ATN-161, bortezomib, cisplatin, endostatin, enterostatin, integrin inhibitors, interferon-α, plasminogen activator-1 (PAI-1), rapamycin, rosiglitazone, statins, thrombospondin-1, TGF-α1 and TGF-α3. Hormesis may also be relevant for drugs that target the vascular endothelial growth factor (VEGF) signalling pathway and for metronomic chemotherapy. Here I argue that hormetic dose-responses present a challenge for the clinical translation of several anti-angiogenic agents and discuss how these problems might be circumvented.

Deletion of 1p32-p36 is the most frequent genetic change and poor prognostic marker in adenoid cystic carcinoma of the salivary glands

PURPOSE

Adenoid cystic carcinoma (ACC) is a relatively uncommon salivary gland malignancy known for its protean phenotypic features and pernicious clinical behavior. Currently, no effective therapy is available for patients with advanced nonresectable, recurrent, and/or metastatic disease. The purpose of this study is to identify prognostic factors other than tumor stage that can be used to predict the outcome of the patients with ACC.

EXPERIMENTAL DESIGN

We used comparative genomic hybridization (CGH) to identify copy number aberrations in 53 primary ACCs. Array CGH and fluorescence in situ hybridization analysis was used to validate CGH results on selected cases. We correlated these copy number aberrations with clinicopathologic factors using Pearson's chi2 or by the two-tailed Fisher exact test. The disease-specific survival and disease-free intervals were generated by the Kaplan-Meier product limit method.

RESULTS

Chromosomal losses (n = 134) were more frequent than gains (n = 74). The most frequent genetic change was the loss of 1p32-p36 in 44% of the cases followed by 6q23-q27, and 12q12-q14. The most frequently gained chromosomal regions were 8 and 18. Of the chromosomal aberrations, loss of 1p32-p36 was the only abnormality significantly associated with patient's outcome.

CONCLUSIONS

This study, for the first time, identifies loss of 1p32-p36 as a significant aberration in ACC. Molecular characterization of 1p32-36 region using the available genomic technologies may lead to the identification of new genes critical to the development of novel therapeutic targets for this disease copy number aberration.

Translocation t(6;14) as the sole chromosomal abnormality in adenoid cystic carcinoma of the base of tongue

We present an adenoid cystic carcinoma of the base of tongue in a 48-year-old male with a restricted chromosomal alteration by cytogenetic and spectral karyotypic analysis (SKY). SKY and G-banding analyses identified the t(6;14)(q25;q13) as the sole structural aberration in all metaphases analyzed. This finding supports a critical role for this event in the development of this tumor. The implications of chromosome 6q translocation in this case and in previously reported adenoid cystic carcinomas are highlighted and discussed.

Comprehensive loss of heterozygosity analysis and identification of a novel hotspot at 3p21 in salivary gland neoplasms

OBJECTIVES

We sought to assess loss of heterozygosity (LOH) profiles of 3p, 6q, 8q, 10q, 12q, 13q, and 17p and to identify the tumor suppressor genes involved in salivary gland neoplasms.

STUDY DESIGN

LOH analysis was performed using 26 microsatellite markers by polymerase chain reaction-polyacrylamide gel electrophoresis method in 20 benign and 6 malignant salivary gland tumors.

RESULTS

Overall, LOH was detected in at least one informative locus in 18 of 20 (90%) of benign tumors and in all of 6 cases of malignant tumors. High LOH frequencies were revealed at the loci D3S1307 (22%, 3p26), D3S966 (41%, 3p21), D6S255 (27%, 6q25), D8S166 (25%, 8q12), D8S199 (21%, 8q24), and D10S1765 (28%, 10q23) in benign tumors, defining the hotspot regions for putative tumor suppressor genes.

CONCLUSIONS AND SIGNIFICANCE

The hotspot regions defined by the present study suggest that new tumor suppressor genes related to the development of salivary gland tumors may reside at several chromosomal loci, including loci at 3p, 6q, 8q and 10q.

Concurrent loss of heterozygosity and copy number analysis in adenoid cystic carcinoma by SNP genotyping arrays

Adenoid cystic carcinoma (ACC) is one of the most common malignancies to arise in the salivary glands, yet very little is known of the genetic alterations that are involved in the pathogenesis of this disease. To further examine the genetic changes that underlie ACC, we analyzed genomic DNA obtained from 22 primary ACC and two ACC-derived cell lines by high-density oligonucleotide single-nucleotide polymorphism genotyping arrays (Affymetrix GeneChip Human Mapping 100K Set). Allelotype calls were analyzed by the Haplotype Correction version of the Linkage Disequilibrium Hidden Markov Model to determine loss of heterozygosity using information derived only from tumor samples. Comparison of data obtained from matched tumor-normal samples suggested that only deletion calls of >3 Mb were reliable. Within these parameters, ACC samples revealed a mean of three deletions per tumor, and no consensus areas of deletion were observed across the majority of tumors. Similarly, copy number analysis of primary hybridization data revealed no consensus areas of gene amplification. This is in contrast to a much higher rate of genomic alterations detected in a cohort of squamous carcinomas analyzed by the same methods. Our data show that most ACC have predominantly stable genomes, which is consistent with the theory that telomere crisis does not play a significant role in early stages of ACC tumor progression. Our data suggest that gene mutation and/or epigenetic events that cannot be detected by assay of gross alteration of chromosomal structure are likely to underlie the malignant transformation events of this tumor type.

Concomitant inhibition of epidermal growth factor and vascular endothelial growth factor receptor tyrosine kinases reduces growth and metastasis of human salivary adenoid cystic carcinoma in an orthotopic nude mouse model

We hypothesized that epidermal growth factor (EGF) receptor (EGFR) activation and vascular endothelial growth factor (VEGF)-induced angiogenic signals are important for the progression and metastasis of human salivary adenoid cystic carcinoma (ACC). To test this hypothesis, we evaluated the therapeutic effect of AEE788, a dual inhibitor of EGF and VEGF receptor (VEGFR) tyrosine kinases, on human salivary ACC. In clinical specimens of salivary ACC, EGF and VEGF signaling proteins were expressed at markedly higher levels than in adjacent normal glandular tissues. We examined the effects of AEE788 on salivary ACC cell growth and apoptosis and on the phosphorylation of EGFR and VEGFR-2 in salivary ACC cells. Treatment of salivary ACC cells with AEE788, alone or in combination with chemotherapy, led to growth inhibition, induction of apoptosis, and dose-dependent inhibition of EGFR and VEGFR-2 phosphorylation. To determine the in vivo antitumor effects of AEE788, nude mice with orthotopic parotid tumors were randomized to receive oral AEE788 alone, paclitaxel alone, cisplatin alone, a combination of AEE788 plus paclitaxel, a combination of AEE788 plus cisplatin, or a placebo. AEE788 inhibited tumor growth and prevented lung metastasis in nude mice. To study the mechanism of interaction between AEE788 and chemotherapy, AEE788 was found to potentiate growth inhibition and apoptosis of ACC tumor cells mediated by chemotherapy. Tumors of mice treated with AEE788 and AEE788 plus chemotherapy exhibited down-regulation of activated EGFR and VEGFR-2, increased tumor and endothelial cell apoptosis, and decreased microvessel density, which correlated with a decrease in the level of matrix metalloproteinase-9 and matrix metalloproteinase-2 expression and a decrease in the incidence of vascular metastasis. These data show that EGFR and VEGFR can be molecular targets for therapy of salivary ACC.

Loss of heterozygosity occurs predominantly, but not exclusively, in the epithelial compartment of pleomorphic adenoma

Pleomorphic adenoma (PA), being the most common benign tumor of the salivary glands, is composed of epithelial and mesenchymal compartments. In this study, we analyzed 19 microsatellite markers from chromosomal arms 6q, 8q, 9p, 12q, and 17p in 31 PAs and 3 carcinoma ex pleomorphic adenomas (CXPAs) as well as 11 other non-PA-related carcinomas of the salivary gland for comparison. In our analysis, we differentiated between epithelial and mesenchymal tissues. Loss of heterozygosity (LOH) in PAs was most often found in 8q (32%) and 12q (29%). Two of the three CXPAs displayed allelic loss at all chromosomal arms investigated, whereas the results of the non-PA-related carcinomas were rather heterogeneous. LOH could not only be detected in the epithelial, but also in the mesenchymal, compartments of a subset of PAs, especially at chromosomal arm 8q. Concerning the CXPAs, we were able to demonstrate allelic losses not only in the malignant epithelial compartment, but also in the residual adenoma parts. Our data give further evidence that alterations in 8q may be an early event in PA tumorigenesis, whereas LOH in 12q may characterize cells with the potential to transform in CXPAs.

Mapping of candidate tumor suppressor genes on chromosome 12 in adenoid cystic carcinoma

Adenoid cystic carcinoma (ACC) is a common malignancy of salivary glands, for which the underlying genetic mechanisms of tumorigenesis are poorly understood. Prior studies in ACC have identified deletions in chromosome 12. To further characterize these changes, we performed an extensive LOH analysis in 58 ACC using a panel of 28 microsatellite markers. Results show 66% overall genetic loss. Three markers (D12S1713, D12S2196, D12S398) are contiguous and define a 6.84 Mb region of deletion at 12q13.11-q13.13. Two other markers (D12S2078, D12S1628) are also contiguous and define a 4.5 Mb region of deletion at 12q24.32-q24.33. The three remaining markers, D12S1056 at 12q14.1, D12S1051 at 12q23.1 and D12S1636 at 12q23.3 define smaller regions of deletion. An analysis of microarray gene expression profiling data available for ACC shows several genes with significant transcriptional downregulation that map to these areas of genetic deletion. This combined genetic and genomic analysis provides several candidate genes to test for functional tumor suppressor activity in ACC.

Genetic and epigenetic alteration profiles for multiple genes in salivary gland carcinomas

As combinations of genetic and/or epigenetic alterations occurring during salivary gland carcinogenesis are largely unknown, we here analyzed 36 salivary gland carcinomas (SGCs) for changes in INK4a/ARF, RB1, p21, p27, PTEN, p53, MDM2 and O6-MGMT genes using methylation specific PCR (MSP), loss of heterozygosity (LOH) assays and mutational analysis with immunohistochemistry (IHC), as well as histone H3 and H4 acetylation status. The RB1 gene was found to be the most frequently methylated (41.7% of cases), while methylation of p27(Kip1) and O6-MGMT were less frequent 8.3% and 5.6%, respectively). Two other genes, p21(Waf1) and PTEN, were unmethylated in the SGCs examined. RB1 methylation significantly correlated with loss of expression as determined by IHC (P=0.03), and also a poor prognosis (P=0.02). p53 mutations were found in 8 cases (22.2%), coupled with p14ARF hypermethylation in two cases. LOH in INK4a/ARF and the RB1 locus was observed in 33.3% and 28.6% of the lesions, respectively. There was no correlation between 9p21 LOH and methylation of the INK4a/ARF gene. Promoter hypermethylation of RB1 coupled with LOH was evident in three samples immuno-negative for RB1. Acetylation of histone H3 and H4 was detected in 6 and 5 cases, respectively. These findings indicate that epigenetic silencing of tumour suppressor genes via promoter hypermethylation might be crucial for salivary gland carcinogenesis, particularly in the RB1 gene. Thus epigenetic events including methylation and acetylation as well as genetic alterations may have important contributions.

Molecular analyses of the candidate tumor suppressor gene, PLAGL1, in benign and malignant salivary gland tumors

Deletions affecting the long arm of chromosome 6 are a characteristic feature of all major subtypes of malignant salivary gland tumors. Moreover, a subgroup of adenoid cystic carcinomas have t(6;9)(q23-25;p21-24) translocations with breakpoints located within the commonly deleted region. Here we have examined the possible involvement of the candidate tumor suppressor gene, PLAGL1, in these deletions and translocations. Northern blot and fluorescence in situ hybridization (FISH) analyses of a series of 27 salivary gland tumors revealed no significant changes in the gene expression or rearrangements of PLAGL1. FISH analysis also demonstrated that the 6q translocation breakpoint in adenoid cystic carcinomas with t(6;9) is proximal to the PLAGL1 locus. Collectively, these results indicate that PLAGL1 is not likely to be the major target gene of the 6q rearrangements in salivary gland tumors.