Stathmin as a marker for malignancy in pheochromocytomas

STNM1 in human cancers: role, function and potential therapy sensitizer

STMN1 belongs to the stathmin gene family, it encodes a cytoplasmic phosphorylated protein, stathmin1, which is commonly observed in vertebrate cells. STMN1 is a structural microtubule-associated protein (MAP) that binds to microtubule protein dimers rather than microtubules, with each STMN1 binding two microtubule protein dimers and preventing their aggregation, leading to microtubule instability. STMN1 expression is elevated in a number of malignancies, and inhibition of its expression can interfere with tumor cell division. Its expression can change the division of tumor cells, thereby arresting cell growth in the G2/M phase. Moreover, STMN1 expression affects tumor cell sensitivity to anti-microtubule drug analogs, including vincristine and paclitaxel. The research on MAPs is limited, and new insights on the mechanism of STMN1 in different cancers are emerging. The effective application of STMN1 in cancer prognosis and treatment requires further understanding of this protein. Here, we summarize the general characteristics of STMN1 and outline how STMN1 plays a role in cancer development, targeting multiple signaling networks and acting as a downstream target for multiple microRNAs, circRNAs, and lincRNAs. We also summarize recent findings on the function role of STMN1 in tumor resistance and as a therapeutic target for cancer.

Comprehensive analysis of CTNNB1 in adrenocortical carcinomas: Identification of novel mutations and correlation to survival

The Wnt/β-Catenin signaling pathway is one of the most frequently altered pathways in adrenocortical carcinomas (ACCs). The aim of this study was to investigate the status of Wnt/β-Catenin signaling pathway by analyzing the expression level of β-Catenin and the mutational status of APC, AXIN2, CTNNB1, and ZNRF3 in ACCs. Mutations in APC, CTNNB1, ZNRF3 and homozygous deletions in ZNRF3 were observed in 3.8% (2/52), 11.5% (6/52), 1.9% (1/52) and 17.3% (9/52) of the cohort respectively. Novel interstitial deletions in CTNNB1 spanning intron 1 to exon 3/intron 3 were also found in 7.7% (4/52) of the tumours. All the observed alterations were mutually exclusive. Nuclear accumulation of β-Catenin, increased expression of Cyclin D1 and significantly higher expression of AXIN2 (p = 0.0039), ZNRF3 (p = 0.0032) and LEF1(p = 0.0090) observed in the tumours harbouring the deletion in comparison to tumours without CTNNB1 mutation demonstrates that the truncated β-Catenin is functionally active and erroneously activates the downstream targets. Significantly lower overall survival rate in patients with tumours harbouring alterations in APC/CTNNB1/ZNRF3 in comparison to those without mutation was observed. In conclusion, the discovery of novel large deletions in addition to the point mutations in CTNNB1 infers that activation of Wnt/β-Catenin pathway via alterations in CTNNB1 occurs frequently in ACCs. We also confirm that alterations in Wnt/β-Catenin signaling pathway members have a negative effect on overall survival of patients.

Stathmin1 overexpression in hypopharyngeal squamous cell carcinoma: A new promoter in FaDu cell proliferation and migration

Stathmin1, a microtubule-destabilizing phosphoprotein, is considered to play a crucial role in regulating cellular microtubule dynamics and controlling mitosis. Previous studies have showed that STMN1 is highly expressed in many human malignancies and is related to development, invasion and metastasis of tumors. However, its expression pattern, clinical performance and functional roles in hypopharyngeal squamous cell carcinoma (HSCC) have not been addressed. In this study, we found that STMN1 was significantly elevated in HSCC and its expression level was correlated with poor differentiation (P<0.001), clinical stage (P<0.001), large tumor size (P=0.001) and lymph node metastasis (P=0.008). A positive correlation between STMN1 and Ki-67 expression was also exhibited. High STMN1 expression predicted poor survival. Furthermore, we found that knockdown of STMN1 by siRNAs inhibited the FaDu cell proliferation and migration. Moreover, decreased STMN1 expression in FaDu cells reversed the acquisition of EMT phenotype by upregulating E-cadherin, as well as reduced vimentin expression at protein and mRNA levels. These results suggested that STMN1 plays an important role in proliferation and migration of HSCC and may be used as a potential prognostic biomarker or therapeutic target of HSCC.

Paragangliomas: update on differential diagnostic considerations, composite tumors, and recent genetic developments

Recent developments in molecular genetics have expanded the spectrum of disorders associated with pheochromocytomas (PCCs) and extra-adrenal paragangliomas (PGLs) and have increased the roles of pathologists in helping to guide patient care. At least 30% of these tumors are now known to be hereditary, and germline mutations of at least 10 genes are known to cause the tumors to develop. Genotype-phenotype correlations have been identified, including differences in tumor distribution, catecholamine production, and risk of metastasis, and types of tumors not previously associated with PCC/PGL are now considered in the spectrum of hereditary disease. Important new findings are that mutations of succinate dehydrogenase genes SDHA, SDHB, SDHC, SDHD, and SDHAF2 (collectively "SDHx") are responsible for a large percentage of hereditary PCC/PGL and that SDHB mutations are strongly correlated with extra-adrenal tumor location, metastasis, and poor prognosis. Further, gastrointestinal stromal tumors and renal tumors are now associated with SDHx mutations. A PCC or PGL caused by any of the hereditary susceptibility genes can present as a solitary, apparently sporadic, tumor, and substantial numbers of patients presenting with apparently sporadic tumors harbor occult germline mutations of susceptibility genes. Current roles of pathologists are differential diagnosis of primary tumors and metastases, identification of clues to occult hereditary disease, and triaging of patients for optimal genetic testing by immunohistochemical staining of tumor tissue for the loss of SDHB and SDHA protein. Diagnostic pitfalls are posed by morphological variants of PCC/PGL, unusual anatomic sites of occurrence, and coexisting neuroendocrine tumors of other types in some hereditary syndromes. These pitfalls can be avoided by judicious use of appropriate immunohistochemical stains. Aside from loss of staining for SDHB, criteria for predicting risk of metastasis are still controversial, and "malignancy" is diagnosed only after metastases have occurred. All PCCs/PGLs are considered to pose some risk of metastasis, and long-term follow-up is advised.

Integrative analysis of miRNA and mRNA expression profiles in pheochromocytoma and paraganglioma identifies genotype-specific markers and potentially regulated pathways

Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare neuroendocrine neoplasias of neural crest origin that can be part of several inherited syndromes. Although their mRNA profiles are known to depend on genetic background, a number of questions related to tumor biology and clinical behavior remain unanswered. As microRNAs (miRNAs) are key players in the modulation of gene expression, their comprehensive analysis could resolve some of these issues. Through characterization of miRNA profiles in 69 frozen tumors with germline mutations in the genes SDHD, SDHB, VHL, RET, NF1, TMEM127, and MAX, we identified miRNA signatures specific to, as well as common among, the genetic groups of PCCs/PGLs. miRNA expression profiles were validated in an independent series of 30 composed of VHL-, SDHB-, SDHD-, and RET-related formalin-fixed paraffin-embedded PCC/PGL samples using quantitative real-time PCR. Upregulation of miR-210 in VHL- and SDHB-related PCCs/PGLs was verified, while miR-137 and miR-382 were confirmed as generally upregulated in PCCs/PGLs (except in MAX-related tumors). Also, we confirmed overexpression of miR-133b as VHL-specific miRNAs, miR-488 and miR-885-5p as RET-specific miRNAs, and miR-183 and miR-96 as SDHB-specific miRNAs. To determine the potential roles miRNAs play in PCC/PGL pathogenesis, we performed bioinformatic integration and pathway analysis using matched mRNA profiling data that indicated a common enrichment of pathways associated with neuronal and neuroendocrine-like differentiation. We demonstrated that miR-183 and/or miR-96 impede NGF-induced differentiation in PC12 cells. Finally, global proteomic analysis in SDHB and MAX tumors allowed us to determine that miRNA regulation occurs primarily through mRNA degradation in PCCs/PGLs, which partially confirmed our miRNA-mRNA integration results.

Somatic mutations in H-RAS in sporadic pheochromocytoma and paraganglioma identified by exome sequencing

CONTEXT

Up to 60% of pheochromocytoma (PCC) and paraganglioma (PGL) are associated with either somatic or germline mutations in established PCC and PGL susceptibility loci. Most unexplained cases are characterized by an increased activity of the RAS/RAF/ERK signaling pathway. Mutations in RAS subtypes H, K, and N are common in human cancers; however, previous studies have been inconsistent regarding the mutational status of RAS in PCC and PGL.

OBJECTIVES

The aim of this study was to identify novel disease causing genes in PCC and PGL tumors.

DESIGN, SETTING, AND PARTICIPANTS

Four benign and sporadic PCC and PGL tumors were subjected to whole exome sequencing using the Illumina HiSeq Platform. Sequences were processed by CLC genomics 4.9 bioinformatics software and the acquired list of genetic variants was filtered against the Catalogue of Somatic Mutations in Cancer database. Findings were validated in an additional 78 PCC and PGL tumor lesions.

RESULTS

Exome sequencing identified 2 cases with somatic mutations in the H-RAS. In total, 6.9% (n = 4/58) of tumors negative for mutations in major PCC and PGL loci had mutations in H-RAS: G13R, Q61K, and Q61R. There were 3 PCC and 1 PGL; all had sporadic presentation with benign tumor characteristics and substantial increases in norepinephrine and/or epinephrine. H-RAS tumors were exclusively found in male patients (P = .007).

CONCLUSIONS

We identified recurrent somatic H-RAS mutations in pheochromocytoma and paraganglioma. Tumors with H-RAS mutations had activation of the RAS/RAF/ERK signaling pathway and were associated with male PCC patients having benign and sporadic disease characteristics. H-RAS could serve as a prognostic and predictive marker as well as a novel therapeutic target.

Expression and phosphorylation of stathmin correlate with cell migration in esophageal squamous cell carcinoma

Microtubules play extensive roles in cellular processes, including cell motility. Stathmin is an important protein which destabilizes microtubules. The essential function of stathmin is closely associated with its phosphorylation status. Stathmin is overexpressed in many human cancers and has a significant relationship with clinical characteristics such as grade, tumor size and prognosis. We demonstrated that stathmin was overexpressed in ESCC tissues using both 2-DE and immunohistochemistry analysis. In addition, overexpression of stathmin was significantly correlated with histological grade in ESCC. However, no correlation was found with age, gender and lymph node metastasis. Knockdown of stathmin with siRNA impaired cell migration in KYSE30 and KYSE410 cells. When EC0156 cells were treated with paclitaxel, stathmin was stably phosphorylated and migration was impaired. These observations suggest that stathmin may have a more important function in ESCC development and migration. The present study provides further understanding of the importance of stathmin in ESCC therapy or diagnosis.

Integrative analysis of neuroblastoma and pheochromocytoma genomics data

Background

Pheochromocytoma and neuroblastoma are the most common neural crest-derived tumors in adults and children, respectively. We have performed a large-scale in silico analysis of altogether 1784 neuroblastoma and 531 pheochromocytoma samples to establish similarities and differences using analysis of mRNA and microRNA expression, chromosome aberrations and a novel bioinformatics analysis based on cooperative game theory.

Methods

Datasets obtained from Gene Expression Omnibus and ArrayExpress have been subjected to a complex bioinformatics analysis using GeneSpring, Gene Set Enrichment Analysis, Ingenuity Pathway Analysis and own software.

Results

Comparison of neuroblastoma and pheochromocytoma with other tumors revealed the overexpression of genes involved in development of noradrenergic cells. Among these, the significance of paired-like homeobox 2b in pheochromocytoma has not been reported previously. The analysis of similar expression patterns in neuroblastoma and pheochromocytoma revealed the same anti-apoptotic strategies in these tumors. Cancer regulation by stathmin turned out to be the major difference between pheochromocytoma and neuroblastoma. Underexpression of genes involved in neuronal cell-cell interactions was observed in unfavorable neuroblastoma. By the comparison of hypoxia- and Ras-associated pheochromocytoma, we have found that enhanced insulin like growth factor 1 signaling may be responsible for the activation of Src homology 2 domain containing transforming protein 1, the main co-factor of RET. Hypoxia induced factor 1α and vascular endothelial growth factor signaling included the most prominent gene expression changes between von Hippel-Lindau- and multiple endocrine neoplasia type 2A-associated pheochromocytoma.

Conclusions

These pathways include previously undescribed pathomechanisms of neuroblastoma and pheochromocytoma and associated gene products may serve as diagnostic markers and therapeutic targets.

Inhibition of stathmin1 accelerates the metastatic process

The oncoprotein stathmin 1 (STMN1) is upregulated in most, if not all, cancers of epithelial cell origin; therefore STMN1 is considered a target for cancer therapy. However, its role during metastasis has not been investigated. Here, we report for the first time that STMN1 strongly inhibits metastatic behavior in both normal epithelial and cancerous epithelial cells. Initially, loss-of-STMN1 compromises cell-cell adhesion. This is followed by epithelial-to-mesenchymal transition (EMT), increased cell migration, and metastasis via cooperative activation of p38 and through TGF-β-independent and -dependent mechanisms. In contrast, expressing STMN1 restores cell-cell adhesion and reverses the metastatic cascade. Primary prostate epithelial cell cultures from benign to undifferentiated adenocarcinoma (UA) clinical biopsies show that EMT-like cells arise while the cancer is still organ-confined and that their emergence is tumor-stage specific. Furthermore, primary EMT-like cells exhibit metastatic behavior both in vitro and in vivo as compared with their non-EMT counterpart. These observations predict that using STMN1 as a generic therapeutic target might accelerate metastasis. Instead, there may be a tumor stage-specific window-of-opportunity in which conserving STMN1 expression is required to inhibit emergence of metastatic disease.

Role of Oncoprotein 18 in metastasis of hepatocellular carcinoma

AIM: To explore the role of Oncoprotein 18 (Op18) in metastasis of hepatocellular carcinoma (HCC).

METHODS: Op18 expression was repressed in HCCLM3 cells by RNA interference, and interference effect was evaluated by RT-PCR and Western blot. Cell adhesion, migration and invasion were analyzed by cell adhesion assay and Transwell assay in vitro. Op18 expression was detected by RT-PCR and immunohistochemistry in 96 HCC specimens with or without metastasis.

RESULTS: Op18 expression was effectively inhibited by RNA interference in HCCLM3 cells. Cell adhesion was significantly suppressed in the RNAi group compared to the mock group (20 min: 0.616 ± 0.057 vs 0.944 ± 0.068; 40 min: 0.740 ± 0.0713 vs 1.196 ± 0.115; 60 min: 1.001 ± 0.083 vs 1.441 ± 0.053; all P < 0.05). Transwell assay revealed that cell migration and invasion decreased in the RNAi group compared to the mock group (migration: 0.145 ± 0.011 vs 0.206 ± 0.008; invasion: 0.127 ± 0.008 vs 0.168 ± 0.012; both P < 0.01). Op18 expression was detected in 96 HCC tissues with or without metastasis. RT-PCR demonstrated that Op18 was overexpressed in HCC tissues with metastasis (n = 48) compared with HCC tissues without metastasis (n = 48, Op18/GAPDH relative ratio: 0.560 ± 0.128 vs 0.414 ± 0.086); and IHC results also indicated that Op18 expression was up-regulated in HCC tissues with metastasis in comparison with HCC tissues without metastasis (integrated density: 624.771 ± 100.032 vs 413.786 ± 71.833, P < 0.01).

CONCLUSION: Overexpression of Op18 may play an important role in HCC metastasis.

Diagnostic tests and biomarkers for pheochromocytoma and extra-adrenal paraganglioma: from routine laboratory methods to disease stratification

The laboratory workup of patients with pheochromocytoma and extra-adrenal paraganglioma (PPGLs) has traditionally focused on biochemical measurements of tumor secretory products or their metabolites, with ultimate diagnosis resting on routine histopathology and immunohistochemistry. While such testing remains important, the needs to distinguish potentially metastatic from benign tumors and to identify tumors with a hereditary basis have stimulated searches for additional means to stratify patients according to risk of metastasis or presence of a particular mutation. Biomarkers based on traditional biochemical tests, such as profiles of catecholamine metabolites and granin-derived peptides, provide utility for both purposes, while novel biomarkers are being identified by proteomic and transcriptomic studies, the latter including microRNA expression profiling. Histopathological scoring methods for predicting metastatic potential, such as the Pheochromocytoma of the Adrenal Gland Scaled Score (PASS), are limited by poor interobserver concordance, discrepant results between studies and incomplete knowledge of how scores relate to genotype. Immunohistochemical staining for succinate dehydrogenase (SDH) subunit B to triage patients for genetic testing of SDH subunit genes illustrates the growing importance of pathology as an adjunct to genetic testing for disease stratification. Although considerable effort has been expended on microarray-based platforms to identify biomarkers of malignancy, as yet, none of those proposed have been demonstrated to reliably discriminate malignant from benign disease any better than the PASS. Because of the heterogeneity of PPGLs and variable time between first appearance of tumors and identification of metastases, any prospective study to establish prognostic efficacy requires large numbers of patients and extended follow-up.

Pheochromocytomas and paragangliomas: assessment of malignant potential

Pheochromocytomas and paragangliomas (PPGLs) are rare catecholamine-secreting tumors which arise from the adrenal glands or sympathetic neuronal tissue. Malignant transformation of these tumors occurs in a significant proportion and may therefore lower overall survival rates. In patients with PPGLs it is impossible to identify malignant disease without the presence of metastatic disease, something which can occur as long as 20 years after initial surgery. Early identification of malignant disease would necessitate a more aggressive treatment approach, something which may result in better disease outcome. We have therefore reviewed possible predictors of malignancy and current developments in order to help clinicians to swiftly assess malignant potential in patients with PPGLs. Currently, there is no absolute marker which can objectively reflect malignant potential. Tumor size is the most reliable predictor and should therefore be used as the baseline characteristic. The combination of various clinical markers (extra-adrenal disease and post-operative hypertension), biochemical markers (high dopamine, high norepinephrine and epinephrine to total catecholamine ratio) and/or histological markers (SNAIL, microRNAs and/or microarray results) can raise or lower the suspicion of malignancy. Furthermore, we discuss how clinical markers may affect biochemical results linked to malignancy, how biochemical results may distinguish hereditary syndromes, the role of imaging in determining malignant potential and tumor detection, and recent results of proposed histological markers.

MicroRNA expression profiling in benign (sporadic and hereditary) and recurring adrenal pheochromocytomas

MicroRNAs are involved in the pathogenesis of several tumors, however, there have been no data on microRNA expression in pheochromocytomas to date. The objective of our study was to perform microRNA expression profiling in sporadic and hereditary benign, and recurring adrenomedullary tumors. Furthermore, the applicability of formalin-fixed paraffin-embedded tissue samples for the analysis of microRNA expression in pheochromocytomas was examined. MicroRNA expression data of three matched frozen and formalin-fixed paraffin-embedded samples were correlated. A total of 21 formalin-fixed paraffin-embedded samples (sporadic benign, multiple endocrine neoplasia 2, von Hippel-Lindau disease, sporadic recurring) were subjected to microRNA expression profiling using microarrays. MicroRNAs with significant differences in expression were validated and sample sizes were extended including tumors from neurofibromatosis type 1 patients by real-time quantitative reverse-transcription PCR (n=33). MicroRNA target prediction was carried out by TargetScan and MicroCosm Targets. Pathway analysis of targets was performed by Ingenuity Pathway Analysis and DIANA mirPath. Furthermore, microRNA expression profiles of a malignant pheochromocytoma and a pair of primary and recurrent tumors were studied by TaqMan Human MicroRNA Cards. MicroRNA expression correlated well between frozen and formalin-fixed paraffin-embedded samples (70-92%). Microarray analysis revealed 16 significantly differentially expressed microRNAs. Five of these were validated by real-time RT-PCR. miR-139-3p, miR-541 and miR-765 were significantly differentially expressed between sporadic benign and von Hippel-Lindau-related pheochromocytomas. Significantly higher expression of miR-885-5p and miR-1225-3p was found in multiple endocrine neoplasia type 2 and sporadic recurring pheochromocytomas, respectively. Pathway analysis revealed the possible involvement of Notch- and G-protein-coupled receptor signaling in tumor recurrence. MicroRNA expression profiles in the primary recurrent and recurring malignant comparisons have been similar. In conclusion, we have proved that formalin-fixed paraffin-embedded samples can be used for the analysis of microRNA expression in pheochromocytomas. MicroRNA expression patterns differ between various sporadic, hereditary and recurring tumors and miR-1225-3p may be useful for identifying recurring pheochromocytomas.

Significance of STMN1 expression in esophageal squamous cell carcinoma

AIM: To investigate the expression of Stathmin 1 (STMN1) protein in esophageal squamous cell carcinoma (ESCC) tissue and cell lines and to evaluate its correlation with the clinicopathologic parameters of ESCC.

METHODS: One-dimensional (1-D) Western blot was performed to determine the expression of STMN1 in 8 ESCC cell lines. Two-dimensional (2-D) Western blot was used to determine modified STMN1 in KYSE180 cells. Western blot and immunohistochemistry (IHC) were employed to determine the expression of STMN1 in ESCC specimens. The chi-square test was used to analyze IHC results.

RESULTS: STMN1 was widely expressed in ESCC cells, including WHCO1, EC0156, KYSE510, KYSE180, KYSE170, KYSE150, KYSE140 and KYSE30 cell lines. Two STMN1 protein spots were detected in KYSE180 cells on 2-D Western blot: one stronger signal and one weaker signal located in more basic area, which suggests that STMN1 protein may be modified in KYSE180 cells. Western blot analysis showed that STMN1 was overexpressed in 69.2% (9/13) of ESCC specimens compared with their normal epithelial counterparts. IHC assay also demonstrated that the positive rate of STMN1 expression was significantly higher in ESCC tissue than in matched adjacent normal tissue (P < 0.05). STMN1 expression is not correlated with age, gender, differentiation, tumor grade and lymph node metastasis.

CONCLUSION: The expression of STMN1 protein is up-regulated in both ESCC tissue and cell lines and may be modified in some ESCC cell lines. STMN1 might exert an oncogenic function in ESCC. Dynamic measurement of STMN1 expression level might aid to evaluate the progression of ESCC.