Correlation of S100A4 expression with invasion and metastasis in oral squamous cell carcinoma

Role of innate host defense proteins in oral cancerogenesis

It is nowadays well accepted that chronic inflammation plays a pivotal role in tumor initiation and progression. Under this aspect, the oral cavity is predestined to examine this connection because periodontitis is a highly prevalent chronic inflammatory disease and oral squamous cell carcinomas are the most common oral malignant lesions. In this review, we describe how particular molecules of the human innate host defense system may participate as molecular links between these two important chronic noncommunicable diseases (NCDs). Specific focus is directed toward antimicrobial polypeptides, such as the cathelicidin LL-37 and human defensins, as well as S100 proteins and alarmins. We report in which way these peptides and proteins are able to initiate and support oral tumorigenesis, showing direct mechanisms by binding to growth-stimulating cell surface receptors and/or indirect effects, for example, inducing tumor-promoting genes. Finally, bacterial challenges with impact on oral cancerogenesis are briefly addressed.

Dione-thiophene conjugate inhibits proliferation and metastasis of nasopharyngeal carcinoma cells through calcium binding protein-P down-regulation

In the present study a series of dione-thiophenol conjugates was prepared and evaluated against nasopharyngeal carcinoma (NPC) cells. MTT assay showed that compound 4a reduced proliferation of C666-1 and CNE-1 cells to 26 and 24%, respectively at 10 μmol/l concentration. Flow cytometry revealed that increasing the concentration of compound 4a from 2 to 10 μmol/l increased the proportion of early apoptotic C666-1 cells from 2.76 to 69.43%. A significant (P < 0.001) decrease in the expression of S100P was caused by compound 4a. In compound 4a treated C666-1 cells the expression of RAGE, EGFR, CD44, MMP2 and MMP9 was markedly decreased. In summary, compound 4a inhibits nasopharyngeal cancer cell proliferation and induces apoptosis through down-regulation of S100P. Moreover, compound 4a also decreases MMP-2, MMP-9, EGFR, CD44 and RAGE expression in nasopharyngeal cancer cells. Thus, compound 4a can be investigated further as a drug candidate for the treatment of nasopharyngeal cancer.

Activation of tissue plasminogen activator by metastasis-inducing S100P protein

S100P protein in human breast cancer cells is associated with reduced patient survival and, in a model system of metastasis, it confers a metastatic phenotype upon benign mammary tumour cells. S100P protein possesses a C-terminal lysine residue. Using a multiwell in vitro assay, S100P is now shown for the first time to exhibit a strong, C-terminal lysine-dependent activation of tissue plasminogen activator (tPA), but not of urokinase-catalysed plasminogen activation. The presence of 10 μM calcium ions stimulates tPA activation of plasminogen 2-fold in an S100P-dependent manner. S100P physically interacts with both plasminogen and tPA in vitro, but not with urokinase. Cells constitutively expressing S100P exhibit detectable S100P protein on the cell surface, and S100P-containing cells show enhanced activation of plasminogen compared with S100P-negative control cells. S100P shows C-terminal lysine-dependent enhancement of cell invasion. An S100P antibody, when added to the culture medium, reduced the rate of invasion of wild-type S100P-expressing cells, but not of cells expressing mutant S100P proteins lacking the C-terminal lysine, suggesting that S100P functions outside the cell. The protease inhibitors, aprotinin or α-2-antiplasmin, reduced the invasion of S100P-expressing cells, but not of S100P-negative control cells, nor cells expressing S100P protein lacking the C-terminal lysine. It is proposed that activation of tPA via the C-terminal lysine of S100P contributes to the enhancement of cell invasion by S100P and thus potentially to its metastasis-promoting activity.

S100P is associated with proliferation and migration in nasopharyngeal carcinoma

In the present study, the function of S100 calcium binding protein P (S100P) in the C666-1 nasopharyngeal carcinoma (NPC) cell line was examined. The levels of S100P protein in NPC tissues were analyzed using immunohistochemistry, and small interfering RNA silenced S100P expression in C666-1 cells. Subsequently, cell proliferation, colony formation, migration and wound-healing assays were performed in order to assess whether the knockdown of S100P was able to influence the biological behavior of C666-1 cells. The expression levels of the receptor for advanced glycation end products (RAGE) were analyzed using a western blot following the inhibition of S100P. The immunohistochemistry results revealed that S100P was elevated in expression in 45/78 (57.7%) of patients with NPC, as compared with 5/30 (16.7%) of patients with benign inflammation. The S100P protein levels correlated with the rates of proliferation and migration in C666-1 cells. Additionally, reduced S100P expression levels altered a series of intracellular events, including the downregulation of epidermal growth factor receptor, cluster of differentiation (CD) 44, matrix metalloproteinase (MMP) 2 and MMP9 protein expression. In addition, RAGE expression was downregulated in the S100P silenced C666-1 cells, as detected by western blot analysis. These data suggest that S100P is important during the development and progression of nasopharyngeal cancer. Therefore, S100P may provide a novel treatment target for NPC.

Overexpression of S100A4 as a biomarker of metastasis and recurrence in oral squamous cell carcinoma

S100A4, a biomarker of epithelial mesenchymal transition (EMT), plays an important role in invasion and metastasis by promoting cancer cell motility. In oral squamous cell carcinoma (OSCC), metastasis results in 90% of cancer associated mortality.

HuD promotes progression of oral squamous cell carcinoma

Head and neck cancer, including oral squamous cell carcinoma (OSCC), ranks as the sixth most common malignancy worldwide. Overall 5-year survival rates of OSCC have not significantly improved during the past 3 decades and the 5-year survival rate is less than 50%. Several invasion grading systems have been employed in OSCC, however, their utility is still controversial. HuD belongs to the Hu protein family and acts as an RNA-binding protein involved in mRNA stability and translational regulation. Although HuD has a pivotal role for neuronal differentiation, the functional role of HuD in OSCCs is still unclear. In this study, we examined HuD expression in 82 OSCC cases. Expression of HuD was observed in 36.6% of OSCCs and significantly associated with histological differentiation, nodal metastasis and mode of invasion. HuD expression in high-metastatic HSC3 cells was higher than in low-metastatic HSC4 cells, and inhibition of invasion ability and activation of caspase-3 were shown by HuD siRNA-treated HSC3 cells. Furthermore, we clarified that HuD regulates expression of vascular endothelial growth factor (VEGF)-A, VEGF-D, matrix metallopeptidase (MMP)-2 and MMP-9. These results suggest that HuD is a useful diagnostic and therapeutic target in OSCCs.

High expression of S100A4 and endoglin is associated with metastatic disease in head and neck squamous cell carcinoma

The presence of cervical metastasis is responsible for high morbidity and mortality rates in individuals with head and neck squamous cell carcinoma (HNSCC). S100A4, a pleiotropic EF-hand calcium-binding protein, is expressed in various normal and cancer cell types. During cancer progression, molecular disturbances in S100A4 can modulate the activity and expression of pre-metastatic and metastatic genes. In this study, we investigated the association between S100A4 methylation status and protein expression as well as the expression of the S100A4 related-proteins annexin A2 (ANXA2), matrix metallopeptidase-9, and endoglin, for metastasis and other clinicopathological parameters in HNSCC. Formalin-fixed, paraffin-embedded blocks of metastatic and non-metastatic HNSCC and matched cervical lymph node (LN) samples (metastatic LN = mLN, non-metastatic = nmLN, and control LN (lymphadenitis) = cLN) were submitted for methylation specific-polymerase chain reaction and immunohistochemistry. Our results showed that S100A4 methylation status failed to demonstrate association with cervical metastasis and other clinicopathological factors related to HNSCC. HNSCC samples from patients that presented with metastatic disease showed high S100A4 and endoglin expression (p < 0.05). In conclusion, molecular disturbances in S100A4 and endoglin expression might regulate the formation of cervical metastasis in HNSCC.

S100A4 mediated cell invasion and metastasis of esophageal squamous cell carcinoma via the regulation of MMP-2 and E-cadherin activity

It is well documented that S100A4 is upregulated in a large amount of invasive tumors and plays a pivotal role in tumor invasion and metastasis. However, the precise role and mechanism S100A4 exerts in the invasion and metastasis of esophageal squamous cell carcinoma (ESCC) have not been fully elucidated to date. Our data demonstrated that S100A4 was overexpressed in human ESCC tissues, especially in ESCC with poor differentiation, deep invasion and lymph node metastasis. Subsequently, the knockdown of S100A4 by RNAi in ESCC cell line (EC-1) could reduce cell invasion, metastasis and proliferation ability in vitro. Most importantly, S100A4 regulated MMP-2 positively and E-cadherin negatively in vivo and in vitro to some extent. Our results suggest that S100A4 is an important factor in the invasion, metastasis and proliferation of ESCC and may control invasion and metastasis at least in part through the regulation of MMP-2 and E-cadherin activity. S100A4 may serve as a biomarker for progression of ESCC and a potential molecular target for biotherapy of ESCC.

The epithelial-mesenchymal transition mediator S100A4 maintains cancer-initiating cells in head and neck cancers

Cancer-initiating cells (CIC) comprise a rare subpopulation of cells in tumors that are proposed to be responsible for tumor growth. Starting from CICs identified in head and neck squamous cell carcinomas (HNSCC), termed head and neck cancer-initiating cells (HN-CIC), we determined as a candidate stemness-maintaining molecule for HN-CICs the proinflammatory mediator S100A4, which is also known to be an inducer of epithelial-mesenchymal transition. S100A4 knockdown in HN-CICs reduced their self-renewal capability and their stemness and tumorigenic properties, both in vitro and in vivo. Conversely, S100A4 overexpression in HNSCC cells enhanced their stem cell properties. Mechanistic investigations indicated that attenuation of endogenous S100A4 levels in HNSCC cells caused downregulation of Notch2 and PI3K (phosphoinositide 3-kinase)/pAKT along with upregulation of PTEN, consistent with biological findings. Immunohistochemical analysis of HNSCC clinical specimens showed that S100A4 expression was positively correlated with clinical grading, stemness markers, and poorer patient survival. Together, our findings reveal a crucial role for S100A4 signaling pathways in maintaining the stemness properties and tumorigenicity of HN-CICs. Furthermore, our findings suggest that targeting S100A4 signaling may offer a new targeted strategy for HNSCC treatment by eliminating HN-CICs.

Gene Expression Signatures of Lymph Node Metastasis in Oral Cancer: Molecular Characteristics and Clinical Significances

Even though lymph node metastasis accounts for the vast majority of cancer death in patients with oral cancer (OC), the molecular mechanisms of lymph node metastasis remain elusive. Genome-wide microarray analyses and functional studies in vitro and in vivo, along with detailed clinical observations, have identified a number of molecules that may contribute to lymph node metastasis. These include lymphangionenic cytokines, cell adhesion molecules, basement membrane-interacting molecules, matrix enzymes and relevant downstream signaling pathways. However, defined gene signatures from different studies are highly variable, which hinders their translation to clinically relevant applications. To date, none of the identified signatures or molecular biomarkers has been successfully implemented as a diagnostic or prognostic tool applicable to routine clinical practice. In this review, we will first introduce the significance of lymph node metastasis in OC, and clinical/experimental evidences that support the underlying molecular mechanisms. We will then provide a comprehensive review and integrative analysis of the existing gene expression studies that aim to identify the metastasis-related signatures in OC. Finally, the remaining challenges will be discussed and our insights on future directions will be provided.

Cancer-associated fibroblasts and epithelial-mesenchymal transition in metastatic oral tongue squamous cell carcinoma

We examined cancer-associated fibroblasts (CAFs) and a panel of immunohistochemical markers of epithelial-mesenchymal transition (EMT) in 19 pair-matched oral tongue squamous cell carcinoma (SCC) and metastatic tumors to regional lymph nodes (RLNs). alpha-Smooth muscle actin (alpha-SMA) was studied to identify CAFs. EMT was studied with syndecan-1, Cadherin-11, fibroblast-specific protein (FSP)-1, secreted protein acidic and rich in cysteine (SPARC) and Twist. Triple immunostaining in RLNs was used to highlight the carcinoma cells (E-cadherin and Ki-67) and their relationship to the CAFs (alpha-SMA). We found that metastatic RLNs hosted CAFs similarly as in pair-matched primary tumors. Expression of EMT markers is common in both primary and metastatic tumors. We demonstrate that metastatic carcinoma cells (Ki-67 positive) downregulate E-cadherin expression at the periphery of cancer islands, where they are in direct contact with CAFs. The supporting connective tissue microenvironment also commonly expresses syndecan-1, Cadherin-11, FSP-1, and SPARC. In conclusion, CAFs are common to both primary and metastatic SCC. We hypothesize that CAFs not only promote tumor invasion but also facilitate metastases, either by cometastasizing and/or being recruited to lymph nodes. Evidence of EMT is common within primary tumors and metastatic SCC and may be further modulated by CAFs.

Nuclear S100A7 is associated with poor prognosis in head and neck cancer

Background

Tissue proteomic analysis of head and neck squamous cell carcinoma (HNSCC) and normal oral mucosa using iTRAQ (isobaric tag for relative and absolute quantitation) labeling and liquid chromatography-mass spectrometry, led to the identification of a panel of biomarkers including S100A7. In the multi-step process of head and neck tumorigenesis, the presence of dysplastic areas in the epithelium is proposed to be associated with a likely progression to cancer; however there are no established biomarkers to predict their potential of malignant transformation. This study aimed to determine the clinical significance of S100A7 overexpression in HNSCC.

Methodology

Immunohistochemical analysis of S100A7 expression in HNSCC (100 cases), oral lesions (166 cases) and 100 histologically normal tissues was carried out and correlated with clinicopathological parameters and disease prognosis over 7 years for HNSCC patients. Overexpression of S100A7 protein was significant in oral lesions (squamous cell hyperplasia/dysplasia) and sustained in HNSCC in comparison with oral normal mucosa (p_trend<0.001). Significant increase in nuclear S100A7 was observed in HNSCC as compared to dysplastic lesions (p = 0.005) and associated with well differentiated squamous cell carcinoma (p = 0.031). Notably, nuclear accumulation of S100A7 also emerged as an independent predictor of reduced disease free survival (p = 0.006, Hazard ratio (HR = 7.6), 95% CI = 1.3−5.1) in multivariate analysis underscoring its relevance as a poor prognosticator of HNSCC patients.

Conclusions

Our study demonstrated nuclear accumulation of S100A7 may serve as predictor of poor prognosis in HNSCC patients. Further, increased nuclear accumulation of S100A7 in HNSCC as compared to dysplastic lesions warrants a large-scale longitudinal study of patients with dysplasia to evaluate its potential as a determinant of increased risk of transformation of oral premalignant lesions.

Self-association of calcium-binding protein S100A4 and metastasis

Elevated levels of the calcium-binding protein S100A4 promote metastasis and in carcinoma cells are associated with reduced survival of cancer patients. S100A4 interacts with target proteins that affect a number of activities associated with metastatic cells. However, it is not known how many of these interactions are required for S100A4-promoted metastasis, thus hampering the design of specific inhibitors of S100A4-induced metastasis. Intracellular S100A4 exists as a homodimer through previously identified, well conserved, predominantly hydrophobic key contacts between the subunits. Here it is shown that mutating just one key residue, phenylalanine 72, to alanine is sufficient to reduce the metastasis-promoting activity of S100A4 to 50% that of the wild type protein, and just 2 or 3 specific mutations reduces the metastasis-promoting activity of S100A4 to less than 20% that of the wild type protein. These mutations inhibit the self-association of S100A4 in vivo and reduce markedly the affinity of S100A4 for at least two of its protein targets, a recombinant fragment of non-muscle myosin heavy chain isoform A, and p53. Inhibition of the self-association of S100 proteins might be a novel means of inhibiting their metastasis-promoting activities.

The basic C-terminal amino acids of calcium-binding protein S100A4 promote metastasis

The calcium-binding protein S100A4 can induce a metastatic phenotype in animal model systems and its expression in various human cancers has been shown to be associated with metastasis and reduced patient survival. Using a series of nested deletion mutants, it is now shown that the two C-terminal lysine residues are required for the enhanced metastasis, invasion and migration abilities that S100A4 confers on cells in a model system of metastasis. Basic C-terminal residues enhance the affinity between S100A4 and its best characterized target, a recombinant C-terminal fragment of non-muscle myosin II heavy chain isoform A (NMMHC-IIA). In wild-type S100A4 protein, the presence of the C-terminal lysine, residue 101, enhances the rate of association between S100A4 and NMMHC-IIA. These results identify the amino acids of S100A4 that are involved in metastasis induction and show that the C-terminal region of S100A4 is a possible target for inhibitors of its metastatic action.

Expression profile of the S100 gene family members in oral squamous cell carcinomas

BACKGROUND

Several of the S100 gene members have been reported to be differentially expressed in many human pathological conditions, in particular, the malignancies. Identification and quantification of the differentially expressed S100 gene members in oral squamous cell carcinoma (OSCC) might facilitate their use as potential diagnostic and/or prognostic markers or targets for therapy.

METHODS

we examined the expression profile of 16 members of the S100 gene family at the mRNA level by semiquantitative reverse transcription-polymerase chain reaction (sRT-PCR) in 27 cases of OSCCs/their pair-wised normal controls obtained from Sudanese patients, and confirmed the sRT-PCR results by performing quantitative real time-polymerase chain reaction (qRT-PCR) for 6 of the 16 genes examined.

RESULTS

With sRT-PCR, 4 (25%; S100A4, S100A6, S100A8, S100A14) out of the 16 S100 gene members examined were found to be significantly down-regulated (P < 0.05) in the tumors compared to the normal controls. None of the S100 gene members examined were found to be significantly up-regulated in the tumors. qRT-PCR results confirmed the significant down-regulation of the S100A4, S100A6, and S100A14 genes in the tumors examined.

CONCLUSION

S100 gene family members might play an important role in the pathogenesis of the OSCCs examined. Findings of the present work warrant in-depth studies of the S100 gene family members, in particular, the S100A4, S100A6, S100A8, and S100A14 to further understand their possible role(s) in OSCC tumorigenesis.

Differential expression of S100 protein subtypes in malignant melanoma, and benign and malignant peripheral nerve sheath tumors

BACKGROUND

Desmoplastic melanoma (DM) may simulate various benign and malignant lesions, including benign peripheral nerve sheath tumors (BPNSTs) and malignant peripheral nerve sheath tumors (MPNSTs). The latter case is diagnostically challenging because DM generally show only S100 protein expression but no reaction to melanocytic markers. S100 family of proteins consists of over 20 members. We report on S100 subtypes in malignant melanomas (MMs), and BPNSTs and MPNSTs to investigate differential expression.

DESIGN

S100A1, S100A2, S100A4, S100A6 and S100B immunostains were performed on 80 MMs including conventional and desmoplastic types, 86 BPNSTs and 77 MPNSTs.

RESULTS

S100A1 expression was seen in > 91% of MMs in a diffuse reaction, whereas BPNSTs showed focal or no reaction. Sixteen percent of MPNSTs focally expressed S100A1 except for one case with diffuse reaction. S100A2 staining was negative or focal in all three groups whereas S100A4 reaction was variable in all three. S100A6 was diffusely expressed in MMs, BPNSTs and MPNSTs. S100B was stained diffusely in MMs and BPNSTs, but its reaction was observed in 30% of MPNSTs in a focal fashion.

CONCLUSION

S100A1 expression was diffuse in most of MMs but absent or focal in BPNSTs and MPNSTs. This may be helpful to distinguish between the two entities.

S100A4: a common mediator of epithelial-mesenchymal transition, fibrosis and regeneration in diseases?

Multiple reports have focused on S100A4's role in cancer progression, specifically its ability to enhance metastasis. However, recent studies have linked S100A4 to several diseases besides cancer, including kidney fibrosis, cirrhosis, pulmonary disease, cardiac hypertrophy and fibrosis, arthritis and neuronal injuries. Common to all these diseases is the involvement of fibrotic and inflammatory processes, i.e. processes greatly dependent on tissue remodelling, cell motility and epithelial-mesenchymal transition. Therefore, the basic biological mechanisms behind S100A4's effects are emerging. S100A4 belongs to the S100 family of proteins that contain two Ca2+-binding sites including a canonical EF-hand motif. S100A4 is involved in the regulation of a wide range of biological effects including cell motility, survival, differentiation and contractility. S100A4 has both intracellular and extracellular effects. Hence, S100A4 interacts with cytoskeletal proteins and enhances metastasis of several types of cancer cells. In addition, S100A4 is secreted by unknown mechanisms, thus, paracrinely stimulating a variety of cellular responses, including angiogenesis and neuronal growth. Although many cellular effects of S100A4 are well described, the molecular mechanisms whereby S100A4 elicits these responses remain largely unknown. However, it is likely that the intracellular and the extracellular effects involve distinct mechanisms. In this review, we explore the possible roles of S100A4 in non-cancer diseases and employ this knowledge to describe underlying biological mechanisms including a change in cellular phenotype towards less tightly adherent cells and activation of fibrotic processes that may explain this protein's involvement in multiple pathologies.

Network-based analysis of calcium-binding protein genes identifies Grp94 as a target in human oral carcinogenesis

To characterise Ca(2+) -binding protein gene expression changes in oral squamous cell carcinomas (OSCCs), we compared the gene expression profiles in OSCC-derived cell lines with normal oral tissues. One hundred Ca(2+) -binding protein genes differentially expressed in OSCCs were identified, and genetic pathways associated with expression changes were generated. Among genes mapped to the network with the highest significance, glucose-regulated protein 94 kDa (Grp94) was evaluated further for mRNA and protein expression in the OSCC cell lines, primary OSCCs, and oral premalignant lesions (OPLs). A significant (P<0.001) overexpression of Grp94 protein was observed in all cell lines compared to normal oral epithelium. Immunohistochemical analysis showed highly expressed Grp94 in primary OSCCs and OPLs, whereas most of the corresponding normal tissues had no protein immunoreaction. Real-time quantitative reverse transcriptase-PCR data agreed with the protein expression status. Moreover, overexpression of Grp94 in primary tumours was significantly (P<0.001) correlated with poor disease-free survival. The results suggested that Grp94 may have potential clinical application as a novel diagnosis and prognostic biomarker for human OSCCs.

Oral squamous cell carcinoma: review of prognostic and predictive factors

Oral squamous cell carcinoma has a remarkable incidence worldwide and a fairly onerous prognosis, encouraging further research on factors that might modify disease outcome. In this review article, the authors approach the factors that may exert influence on the prognosis and eventually guide the selection of patients for more aggressive therapies. Published scientific data was collected, selected, and grouped into 3 main clusters: patient-, tumor-, and treatment-related factors. Well established aspects are discussed, but also those less common or with only supposed usefulness. Disease staging, extracapsular dissemination, resection margin free of disease, and tumor thickness are factors with high influence on the prognosis. There has been an increasing interest in the study of tumor molecular factors, and some have been strongly correlated with the outcome, showing promising pathways for the future development of more effective prognosis systems and anticancer therapies.

S100A4 (Mts1) gene overexpression is associated with invasion and metastasis of papillary thyroid carcinoma

Tumour cell invasion and metastasis are the hallmark of malignant neoplasm. S100A4 is a member of small calcium-binding protein family and is involved in the cell proliferation and cancer progression. S100A4 is capable of inducing metastasis in animal models and is associated with aggressive phenotype of human tumours. We previously identified S100A4 as a candidate gene involved in anaplastic thyroid cancer metastasis by microarray analysis. To further determine whether S100A4 overexpression is associated with thyroid tumour invasion and metastasis, in the present study, we examined S100A4 gene expression in six benign multinodular goitres (MNG) and 28 matched samples of adjacent normal thyroid tissue (N), primary (T) and metastatic (M) papillary thyroid carcinomas (PTC) by immunohistochemistry and real-time reverse transcription–polymerase chain reaction (RT-PCR) analysis. This gave us the advantage of directly comparing levels of S100A4 expression within the same genetic background. Using immunohistochemistry, we found that high levels of S100A4 were detected in 24 of 28 (86%) PTC specimens and their local regional lymph node or distant metastases. No S100A4 staining was observed in normal thyroid tissues and simple MNG. However, in MNG coexistent with PTC, moderate focal staining could be found in 11 of 15 MNG adjacent to PTC. The S100A4 was stained more intensely in invading fronts than in central portions of both T and M. Real-time RT–PCR analysis of primary tumours and their matched lymph node metastasis demonstrated that significantly higher S100A4 transcripts were present in metastatic tumours as compared to the primary tumours (P<0.01). These data suggest that overexpression of S100A4 is associated with thyroid tumour invasion and metastasis and it may be a potential target for therapeutic intervention.

Identification of three gene candidates for multicellular resistance in colon carcinoma

Solid tumours display elevated resistance to chemo- and radiotherapies compared to individual tumour derived cells. This so-called multicellular resistance (MCR) phenomenon can only be partly explained by reduced diffusion and altered cell cycle status; even fast growing cells on the surface of solid tumours display MCR. Multicellular spheroids (MCS) recapture this phenomenon ex vivo and here we compare gene expression in exponentially growing MCS with gene expression in monolayer culture. Using an 18,664 gene microarray, we identified 42 differentially expressed genes and three of these genes can be linked to potential mechanisms of MCR. A group of interferon response genes were also up-regulated in MCS, as were a number of genes that that are indicative of greater differentiation in three-dimensional cultures.

Profiling early head and neck cancer

Head and neck squamous-cell carcinoma (HNSCC) is the sixth most common cancer worldwide and, disappointingly, survival rates are not improving. Moreover, HNSCC has a severe impact on the quality of life of patients and survivors, and the significant morbidity subsequent to treatment often mandates long-term multidisciplinary care, which places significant financial pressures on the treating institution. Therefore, prevention and early diagnosis of high-risk pre-malignant lesions are high priorities for reducing deaths due to head and neck cancer. Recent advances have begun to elucidate the different aetiologies of HNSCCs in relation to previous pre-malignancies and to identify which pre-malignant lesions are likely to progress to malignancy.

Down-Regulation of S100C Is Associated with Bladder Cancer Progression and Poor Survival

Purpose: The goal of this study was to identify proteins down-regulated during bladder cancer progression.

Experimental design: By using comparative proteome analysis and measurement of mRNA, we found a significant down-regulation of S100C, a member of the S100 family of proteins, in T24 (grade 3) as compared with RT4 (grade 1) bladder cancer cell lines. Moreover, quantification of the mRNA level revealed that decreased expression of the protein reflects a low level of transcription of the S100C gene. Based on this observation, we quantified the S100C mRNA expression level with real-time PCR in bladder cancer biopsy samples obtained from 88 patients followed for a median of 23 months (range, 1-97 months).

Results: We found a significantly lower mRNA expression of S100C in connective tissue invasive tumors (T1, P = 0.0030) and muscle invasive tumors [(T2-T4), P &lt; 0.0001] compared with superficial tumors (Ta). A negative correlation between S100C and histopathologic grade (P = 0.0003) was also observed. Furthermore, the papillary type showed higher expression of S100C than did the solid type of the tumor (P &lt; 0.0001). Importantly, we found that loss of S100C was associated with survival in bladder cancer patients (P = 0.0006).

Conclusions: Our results show that low expression of S100C is associated with poor survival in patients with bladder cancer. Furthermore, loss of S100C in T1 as compared with Ta stage tumors emphasize that S100C expression is suppressed early during bladder cancer development.

Role of intracellular S100A4 for migration of rat astrocytes

S100A4 is a member of the EF-hand family of calcium-binding proteins, first identified in tumor cells, and implicated in tumor invasion and metastasis. Intracellular upregulation of S100A4 is associated with increased motility of tumor cells. Extracellular application of S100A4 increases the motility of glioma cells in vitro. We showed previously that astrocytes in spinal cord and brain white matter also express S100A4. This expression is markedly increased in reactive white matter astrocytes after injury. Here, we have explored how changes in intracellular S100A4 affect migration of astrocytes. We produced cultures of white matter, S100A4 expressing astrocytes, and developed a small interfering (si) RNA approach to specifically eliminate S100A4 expression in these cells, and compared the migration of astrocytes expressing S100A4 with astrocytes transfected with S100A4 siRNA. As a "positive control" we used S100A4 expressing C6 glioma cells. In contrast to malignant cells, S100A4 expressing astrocytes increased their migration capacity after S100A4 siRNA treatment. At the same time, and in parallel with increased migration, white matter astrocytes increased their expression of metalloproteinases MMP-9 and MT1-MMP. The addition of MMP-2/MMP-9 inhibitor resulted in a significant inhibition of migration in S100A4 siRNA-treated astrocytes. These findings indicate that S100A4 has a stabilizing function in reactive white matter astrocytes, a function that may contribute to the development of a rigid, growth-inhibitory glial scar.