Organ specific regulation of tumour invasiveness and gelatinolytic activity at the invasive front

Matrix metalloproteinase-2 mediates ribosomal RNA transcription by cleaving nucleolar histones

Cell proliferation and survival require continuous ribosome biogenesis and protein synthesis. Genes encoding ribosomal RNA are physically located in a specialized substructure within the nucleus known as the nucleolus, which has a central role in the biogenesis of ribosomes. Matrix metalloproteinase-2 was previously detected in the nucleus, however, its role there is elusive. Herein we report that matrix metalloproteinase-2 resides within the nucleolus to regulate ribosomal RNA transcription. Matrix metalloproteinase-2 is enriched at the promoter region of ribosomal RNA gene repeats, and its inhibition downregulates preribosomal RNA transcription. The N-terminal tail of histone H3 is clipped by matrix metalloproteinase-2 in the nucleolus, which is associated with increased ribosomal RNA transcription. Knocking down/out matrix metalloproteinase-2, or inhibiting its activity, prevents histone H3 cleavage and reduces both ribosomal RNA transcription and cell proliferation. In addition to the known extracellular roles of matrix metalloproteinase-2 in tumor growth, our data reveal an epigenetic mechanism whereby intranucleolar matrix metalloproteinase-2 regulates cell proliferation through histone clipping and facilitation of ribosomal RNA transcription.

Bryne's grading system predicts poor disease-specific survival of oral squamous cell carcinoma: a comparative study among different histologic grading systems

OBJECTIVES

The aim of this study was to access the prognostic value of 4 histopathologic grading systems of oral squamous cell carcinoma (OSCC): The World Health Organization (WHO), Anneroth, Bryne (1989), and Bryne (1992).

STUDY DESIGN

Eighty-five cases of OSCC diagnosed between 1996 and 2010 at the Clinics Hospital of Porto Alegre (Porto Alegre, Brazil) were included. Slides stained with hematoxylin and eosin were obtained, and a histologic grade was assigned on the basis of the consensus of 3 expert oral pathologists, who were blinded to the clinicopathologic factors. Each system was correlated with proliferative labeling index, accessed through Ki67 immunostaining, clinicopathologic factors, patient outcome (alive or deceased), and survival time.

RESULTS

The increase in Bryne (1992) histologic grades was accompanied by an increase in proliferative labeling index. Moreover, this system was the only one associated with patient outcome (P = .01) and survival. Bryne (1992) grading system grade III tumors were associated with poor disease-specific survival according to univariate and multivariate cox regression analyses and the log-rank test (P < .05). The other systems evaluated presented no association with patients' outcome or survival.

CONCLUSIONS

The Bryne (1992) grading system is more effective in predicting survival in OSCC compared with the systems proposed by the WHO, Anneroth, or Bryne (1989).

Matrix-metalloproteinases as targets for controlled delivery in cancer: An analysis of upregulation and expression

While commonly known for degradation of the extracellular matrix, matrix metalloproteinases (MMPs) exhibit broad potential for use in targeting of bioactive and imaging agents in cancer treatment. MMPs are upregulated at all stages of expression in cancers. A comprehensive analysis of published literature on expression of all MMP subtypes at the genetic, protein, and activity levels in normal and diseased tissues indicate targeting applicability in a variety of cancers. This expression significantly increases at advanced cancer stages, providing an improved opportunity for controlled release in higher-stage patients. Since MMPs are integral at every stage of metastasis, MMP roles in cancer are discussed with a focus on MMP distribution and mobility within cells and tumors for cancer targeting applications. Several strategies for MMP utilization in targeting - such as matrix degradation, MMP cleavage, MMP binding, and MMP-induced environmental changes - are addressed.

Molecular changes in invasive front of oral cancer

Treatment planning for oral squamous cell carcinoma (OSCC) is based on the clinical TNM (Tumor, Node and Metastasis) classification. This system operates on the assumption that small tumours without clinical spread have a better prognosis than larger tumours with metastases. However, it is a well-known fact that some tumours with the same clinical staging show different growth patterns and clinical behaviour. This makes the prognosis for patients with OSCC difficult to predict on the basis of clinical staging alone. Although many histopathological characteristics of OSCC have been identified as prognostic factors, none is believed to be completely infallible. Therefore, a great need exists for more reliable prognostic markers, which will assist in treatment decisions. It is now well documented that several molecular events of significance for tumour spread, such as gain and loss of adhesion molecules, secretion of proteolytic enzymes, increased cell proliferation and initiation of angiogenesis occur at the tumour–host interface or invasive front, where the deepest and presumably most aggressive cells reside. This review describes the various molecular events and interactions, which take place in the invasive front of the OSCC, and elucidates their role as prognostic markers.

Fms-like tyrosine kinase 3 receptor ligand (Flt3L)-based vaccination administered with an adenoviral vector prevents tumor growth of colorectal cancer in a BALB/c mouse model

PURPOSE

Colorectal cancer is the third most frequent cancer in industrial nations. Therapeutic strategies to treat metastatic disease and prevent recurrence are needed. Anti-tumor immunity can be induced by dendritic cells. Dendritic cells can be expanded by the fms-like tyrosine kinase 3 ligand (Flt3L) in vivo. The aim of this study was to develop an adenoviral-based immune-gene therapy of colorectal cancer with Flt3L in a BALB/c mouse model.

METHODS

A new Flt3L-encoding adenoviral vector (pAdFlt3L) was administered in two approaches in a CT26 colon cancer model in female BALB/c mice. In the therapeutic approach, pAdFlt3L was injected into the tail vein or directly into subcutaneous CT26 colon carcinoma tumors in BALB/c mice. In the vaccination protocol, mice were vaccinated with CT26 cell lysate and pAdFlt3L subcutaneous prior to subcutaneous application of vital CT26 cells.

RESULTS

Application of pAdFlt3L led to high levels of Flt3L in vitro and in vivo. Significant expansion of dendritic cells after application of pAdFlt3L in vivo was confirmed by the use of CD11c and CD11b surface markers in immunohistochemistry and flow cytometry (p = 0.019). In the therapeutic approach, neither intravenous nor intratumoral treatments with pAdFlt3L lead to regression of CT26 tumors. In the vaccination protocol, vaccination completely prevented tumor growth and resulted in superior survival compared to control mice (p < 0.001).

CONCLUSIONS

Our results demonstrate that immunostimulatory therapy with pAdFlt3L is effective to prevent tumor development through vaccination and may represent a therapeutic tool to prevent metastatic disease.

Tissue- and cell-specific co-localization of intracellular gelatinolytic activity and matrix metalloproteinase 2

Matrix metalloproteinase 2 (MMP-2) is a proteolytic enzyme that degrades extracellular matrix proteins. Recent studies indicate that MMP-2 also has a role in intracellular proteolysis during various pathological conditions, such as ischemic injuries in heart and brain and in tumor growth. The present study was performed to map the distribution of intracellular MMP-2 activity in various mouse tissues and cells under physiological conditions. Samples from normal brain, heart, lung, liver, spleen, pancreas, kidney, adrenal gland, thyroid gland, gonads, oral mucosa, salivary glands, esophagus, intestines, and skin were subjected to high-resolution in situ gelatin zymography and immunohistochemical staining. In hepatocytes, cardiac myocytes, kidney tubuli cells, epithelial cells in the oral mucosa as well as in excretory ducts of salivary glands, and adrenal cortical cells, we found strong intracellular gelatinolytic activity that was significantly reduced by the metalloprotease inhibitor EDTA but not by the cysteine protease inhibitor E-64. Furthermore, the gelatinolytic activity was co-localized with MMP-2. Western blotting and electron microscopy combined with immunogold labeling revealed the presence of MMP-2 in different intracellular compartments of isolated hepatocytes. Our results indicate that MMP-2 takes part in intracellular proteolysis in specific tissues and cells during physiological conditions.

S100A4 expression in xenograft tumors of human carcinoma cell lines is induced by the tumor microenvironment

Increased expression of the invasion- and metastasis-associated protein S100A4 is found in many types of cancer, but the regulation of S100A4 expression is poorly understood. The microenvironment surrounding tumors has a significant effect on tumor progression, and in the present study, we investigated the role of the microenvironment in the expression of S100A4. Tumors of three different human carcinoma cell lines were established in the tongue or skin of mice, and S100A4 expression was assessed by quantitative RT-PCR, Western blotting, and immunohistochemical analysis in tumors and stromal tissue and in cancer cells grown in vitro. Tongue tumors of the oral squamous cell carcinoma cell line HSC-4 showed a pronounced increase in S100A4 expression during tumor growth, whereas only a minor increase was detected in skin tumors of the same cell line. The S100A4 expression correlated with the methylation status of cytosine-guanine sites in the first intron of the gene. For all cell lines, S100A4 expression in the tumor stroma was related to the presence of inflammatory cells rather than to the level of S100A4 in the tumor cells.

Stromal impact on tumor growth and lymphangiogenesis in human carcinoma xenografts

Squamous cell carcinomas (SCCs) arising in the oral cavity are associated with poor survival, mainly due to metastatic disease. In contrast, skin SCCs rarely metastasize and are usually curable. To study influence of tongue and skin stroma on cancer growth and induction of lymphangiogenesis, xenograft tumors of human carcinoma cells were established either in tongue or skin of BALB/c nude mice. Two oral and two skin SCC cell lines were used, as well as an endometrial adenocarcinoma cell line. Tongue tumors established from all cell lines were larger than corresponding skin tumors. Peritumoral lymphatic vessel density was up to five times higher in tongue than in corresponding skin tumors, and mRNA level of the lymphangiogenic growth factor vascular endothelial growth factor (VEGF)-C was twice as high in tongue tumors compared with corresponding skin tumors. Contrary to lymphatic vessel density, blood vessel density was higher in skin tumors than in tongue tumors. In a cohort of patient samples, lymphatic vessel density was found to be higher in tongue SCCs compared with skin SCCs, supporting a clinical relevance of our findings. Our results show that the tumor stroma has a profound impact on cancer growth and induction of lymphangiogenesis and angiogenesis. The difference in lymphatic vessel density between tongue and skin tumors may be important in directing metastatic potential of tumors arising in these organs.