Laminin alpha2 chain (merosin M chain) distribution and VEGF, FGF(2), and TGFbeta1 gene expression in angiogenesis of supraglottic, lung, and breast carcinomas

Global gene expression analysis of reactive stroma in prostate cancer

PURPOSE

Marked reactive stroma formation, designated as grade 3 reactive stroma, is associated with poor outcome in clinically localized prostate cancer. To understand the biological processes and signaling mechanisms underlying the formation of such reactive stroma, we carried out microarray gene expression analysis of laser-captured reactive stroma and matched normal stroma.

EXPERIMENTAL DESIGN

Seventeen cases of reactive stroma grade 3 cancer were used to laser-capture tumor and normal stroma. Expression analysis was carried out using Agilent 44K arrays. Up-regulation of selected genes was confirmed by quantitative reverse transcription-PCR. Expression data was analyzed to identify significantly up- and down-regulated genes, and gene ontology analysis was used to define pathways altered in reactive stroma.

RESULTS

A total of 544 unique genes were significantly higher in the reactive stroma and 606 unique genes were lower. Gene ontology analysis revealed significant alterations in a number of novel processes in prostate cancer reactive stroma, including neurogenesis, axonogenesis, and the DNA damage/repair pathways, as well as evidence of increases in stem cells in prostate cancer reactive stroma.

CONCLUSIONS

Formation of reactive stroma in prostate cancer is a dynamic process characterized by significant alterations in growth factor and signal transduction pathways and formation of new structures, including nerves and axons.

Laminin expression in juvenile angiofibroma indicates vessel's early developmental stage

CONCLUSION

This study confirms the wide range of vascular architecture in juvenile angiofibromas. Proof of laminin alpha2 expression in tumour vessels is suggested to indicate presence of vessels of early developmental stage in juvenile angiofibromas, supporting the concept that plexus remnants of the first branchial arch artery contribute to the vascular tumour component.

OBJECTIVES

Laminins, one of the major components of vascular wall basement membranes, have been implicated in tumour growth and have been shown to have developmentally regulated expression patterns. The goal of this study was to analyse the expression of laminins in juvenile angiofibromas.

MATERIALS AND METHODS

A detailed analysis of the laminin isoform expression was performed by immunofluorescence staining for laminin chains alpha1, alpha2, alpha3, alpha4, alpha5, beta1, beta2, beta3, gamma1, gamma2, and gamma3 on cryosections of 10 juvenile angiofibromas and inferior nasal turbinate tissue for control.

RESULTS

Vascular staining of the different laminin chains revealed areas of differential vessel density in juvenile angiofibromas and irregularities in vessel size, configuration and architecture. Similar to vessels in nasal turbinates, laminins alpha4, alpha5, beta1, beta2 and gamma1 were found to be expressed in juvenile angiofibroma vessels. In contrast to vessels of nasal turbinates, staining for alpha2 and alpha3 chains was only detected in vessels of juvenile angiofibromas.

Pathophysiological mechanisms of angiogenesis

The growth of new blood vessels may be either beneficial or harmful. The angiogenic process may be measured by a variety of techniques, although it may often be the quality rather than quantity of resulting blood vessels that determines function. Endothelial cells play a key role in the initiation of angiogenesis, and vascular endothelial growth factor (VEGF) may be viewed as a prototypical direct-acting angiogenic factor. VEGF acts through multiple cell surface receptors and signaling pathways to stimulate endothelial cell proliferation, survival, and migration. By inducing other growth factor expression, VEGF stimulates a cascade of angiogenic activity. Different tissues may utilize various angiogenic pathways that are modulated by diverse host tissue responses. Furthermore, a single tissue may progress through a sequence of angiogenic pathways, for example, as acute injury progresses to chronic inflammation. The phenotype of the resulting neovasculature is critically dependent on the context in which it is formed. Biomarkers of angiogenesis are being developed as an aid to assessing human disease. Histological assessment of vascular density and angiogenic factor expression, in vivo imaging, Doppler ultrasound, and biofluid assays each may have clinical utility. Therapeutic targeting of angiogenesis will depend both on the generation of acceptable pharmacological agents and on the identification of patients who may and do gain benefit from such treatments.

In situ identification of genes regulated specifically in fibroblasts of human basal cell carcinoma

Basal cell carcinoma (BCC) is characterized by slow growth, virtual absence of metastases, and strong stroma-dependency. Cancer-associated fibroblasts (CAFs) in the tumor stroma influence tumor growth, invasion, and metastasis. To comprehensively characterize CAFs of BCC in their in situ cancer environment, laser capture microdissection, linear gene amplification, microarray analysis, and quantitative real-time PCR (qRT-PCR) were combined. Pair-wise comparison of gene expression of microdissected CAFs and corresponding normal perifollicular fibroblasts identified 65 genes that were significantly upregulated in at least two of three different patients. Among the annotated genes, as many as 13 genes encoded secreted proteins, of which six were previously implicated as CAF-associated proteins in various tumor types. Four of the seven novel CAF genes--matrix Gla-protein, secreted frizzled-related protein 2, angiopoietin-related protein-2, and platelet-derived growth factor receptor-like protein--were selected for further analyses by qRT-PCR and were found to be frequently upregulated in CAFs of three independent BCC tissues. Analyses of CAFs from squamous cell cancer, prostate cancer, and colon cancer did not indicate that these genes were upregulated in these cancers. This study thus validates a novel approach for comprehensive characterization CAFs in their in situ environment of BCC. The results suggest a specific expression profile of CAFs in BCC possibly accounting for disease-specific pathological roles.

Laminin alpha2 chain-positive vessels and epidermal growth factor in lung neuroendocrine carcinoma: a model of a novel cooperative role of laminin-2 and epidermal growth factor in vessel neoplastic invasion and metastasis

Capillaries expressing the laminin alpha2 chain in basement membranes may be considered early developing vessels in normal and neoplastic human tissues. Therefore, we investigated whether up-regulation of this extracellular matrix protein favors transendothelial migration of neoplastic cells and then metastasis. In lung small and large cell neuroendocrine carcinomas, which exhibit a stronger metastatic tendency among carcinomas, laminin alpha2 chain-positive vessels were more numerous than in carcinoid tumors and supraglottis, breast, and lung non-small cell carcinomas, suggesting a direct relationship between these vessels and metastasis. In vitro studies showed that epidermal growth factor (EGF) induced a more efficient migration of the AE-2 lung neuroendocrine carcinoma cell line through the purified laminin alpha2 chain rather than through the laminin beta1 chain and fibronectin. AE-2 cells constitutively expressed all EGF receptors and the alpha6beta1 integrin, which is one of the laminin alpha2 chain receptors. EGF up-regulated alpha6beta1 expression in several tumors. In this regard, we show that EGF increased the chemo-kinetic migration of AE-2 cells through EAHY endothelial monolayers, which was inhibited by the anti-alpha6 integrin chain monoclonal antibody. These data indicate that laminin alpha2 chain and alpha6beta1 may be mutually involved in EGF-dependent migration of AE-2 cells and that laminin alpha2 chain-positive vessels may favor metastasis of EGF-dependent tumors.

Mouse models for human lung cancer

In recent years several new mouse models for lung cancer have been described. These include models for both non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). Tumorigenesis in these conditional mouse tumor models can be initiated in adult mice through Cre-recombinase-induced activation of oncogenic mutations in a subset of the cells. They present a marked improvement over mouse models that depend on carcinogen induction of tumors. These models permit us to study the consecutive steps involved in initiation and progression and allow us to address questions like the cell of origin, and the role of cancer stem cells in the maintenance of these tumors. They now need to be validated as suitable preclinical models for intervention studies in which questions with respect to therapy response and resistance can be addressed.

Gene expression profiling of normal human pulmonary fibroblasts following coculture with non-small-cell lung cancer cells reveals alterations related to matrix degradation, angiogenesis, cell growth and survival

Increasing evidence supports a major role for the microenvironment in carcinoma formation and progression. The influence of the stroma is partly mediated by signalling between epithelial tumor cells and neighboring fibroblasts. However, the molecular mechanisms underlying these interactions are largely unknown. To mimic the initial steps of invasive carcinoma in which tumor cells come in contact with normal stromal cells, we used a coculture model of non-small-cell lung cancer tumor cells and normal pulmonary fibroblasts. Using DNA filter arrays, we first analysed the overall modification of gene expression profile after a 24 h period of coculture. Next, we focused our interest on the transcriptome of the purified fibroblastic fraction of coculture using both DNA filter arrays and a laboratory-made DNA microarray. These experiments allowed the identification of a set of modulated genes coding for growth and survival factors, angiogenic factors, proteases and protease inhibitors, transmembrane receptors, kinases and transcription regulators that can potentially affect the regulation of matrix degradation, angiogenesis, invasion, cell growth and survival. This study represents to our knowledge the first attempt to dissect early global gene transcription occurring in a tumor-stroma coculture model and should help to understand better some of the molecular mechanisms involved in heterotypic signalling between epithelial tumor cells and fibroblasts.

Impaired angiogenesis in aging is associated with alterations in vessel density, matrix composition, inflammatory response, and growth factor expression

It is generally accepted that angiogenesis is delayed in aging. To define the effects of age on the neovascular response, polyvinyl alcohol sponges were implanted SC in young (6-8 months old, n=11) and aged (23-25 months old, n=13) mice and sampled at 14 and 19 days. Angiogenic invasion was significantly delayed in aged mice at 14d relative to young at 14d (% area of invasion 9.0 +/- 3.7 vs 19.0 +/- 5.6; p=0.02). Although microvessel morphology and basement membrane composition were similar between the age groups, a significant decrease in capillary density was noted in aged tissues at 14d (7.5 +/- 4.1) and 19d (12.1 +/- 2.8) relative to young at 14d (18.7 +/- 2.3) (p<0.01 A14d vs Y14d). In comparison to young at 14d, the inflammatory response was decreased by 43 +/- 2.9% and 36 +/- 7.8% in aged mice at 14d and 19d, respectively. Tissues of aged mice showed less newly deposited collagen. There was a lack of expression of transforming growth factor-beta1 (TGF-beta1) and vascular endothelial growth factor (VEGF) in aged mice at 14d (0.63 +/- 0.3) and 19d (1.14 +/- 0.5) vs young at 14d (1.92 +/- 0.5) (p< or =0.01 A14d vs Y14d for VEGF). However, similar production of VEGF receptor2 was observed. In contrast to young mice, there was significantly increased expression of thrombospondin-2 (TSP-2) in aged mice from 14d (14.6 x 10(3) +/- 7.3 x 10(3)) to 19d (34.9 x 10(3) +/- 17 x 10(3)). We conclude that angiogenesis in aging is not merely delayed, but is altered due to multiple impairments.