Perlecan Knockdown in Metastatic Prostate Cancer Cells Reduces Heparin-binding Growth Factor Responses in vitro and Tumor Growth in vivo

Perlecan (Pln) is a major heparan sulfate proteoglycan (HSPG) of extracellular matrices and bone marrow stroma. Pln, via glycosaminoglycans in domains I and V, acts as a co-receptor for delivery of heparin binding growth factors (HBGFs) that support cancer growth and vascularization. Specifically, glycosaminoglycans bind HBGFs and activate HBGF receptors, including those for FGF-2 and VEGF-A. The contribution of Pln to prostate cancer growth was tested using a ribozyme approach to knockdown Pln expression levels. Transfection into the androgen-independent, bone targeted prostate cancer line, C4-2B, and efficient stable knockdown of Pln was demonstrated by quantitative PCR, immunohistochemistry and immunoblotting. Three individually isolated subclones with 75–80% knockdown in Pln mRNA, protein expression and secretion into ECM were used to study in vitro growth responses to FGF-2 and VEGF-A. While cells with normal Pln levels responded to both HBGFs, knockdown cells responded poorly. All lines responded to serum growth factors and IGF-I. Anchorage-independent growth assays showed reduced colony size and cohesiveness by all Pln deficient subclones compared to parental C4-2B cells. In vivo effects of Pln knockdown were measured by inoculating knockdown and control ribozyme transfected cell lines into athymic mice. A reduced growth rate, smaller tumor size, diminished vascularization and failure to elevate serum PSA characterized mice bearing Pln knockdown C4-2B cells. Poor vascularization correlated with reduced levels of VEGF-A secreted by Pln knockdown lines. We conclude that Pln is an essential ECM component involved in growth responses of metastatic prostate cancer cells to HBGFs deposited in local and metastatic microenvironment.     

Matrix metalloproteinase 7 and perlecan in oral epithelial dysplasia and carcinoma in situ: an aid for histopathologic recognition of their cell proliferation centers

Background:  As one of the valuable tools for differential diagnoses of oral epithelial dysplasia, carcinoma in situ (CIS) and squamous cell carcinoma (SCC), we have proposed the immunohistochemistry for perlecan, a heparan sulfate proteoglycan (HSPG). As HSPGs have been shown to be extracellular docking molecules for matrix metalloproteinase (MMP) 7, our aim was to determine the expression mode of MMP-7 in these lesions for its possible diagnostic aid for oral borderline malignancies.
Methods:  Twenty cases each of moderate dysplasia, CIS, SCC, and normal/hyperplastic/mild dysplastic epithelia of the tongue and buccal mucosa were immunohistochemically examined for MMP-1, -2 and -7 in reference to their perlecan immunolocalization.
Results:  The expression of all three MMPs in the normal mucosal epithelium was restricted mainly to the parabasal layers. The most striking finding was strong expression of MMP-7 in epithelial dysplasia with a two-phase appearance: a clear demarcation of MMP-7-immunopositive (+) lower dysplastic/basaloid cells from non-positive upper keratinized cells. MMP-7+ cells were spread over the whole epithelial layer of CIS. In SCC, MMP-7 positivity was reduced from carcinoma cells but instead appeared in stromal cells. These expression profiles of MMP-7 resembled those of perlecan. MMP-1 and MMP-2 exhibited a similar but much weaker staining than MMP-7.
Conclusion:  These results suggest that the enhanced metabolism of perlecan associated with MMP-7 plays an important role in the cell proliferation of oral epithelia in their malignant transformation process, and that MMP-7 immunohistochemistry may be a valuable aid for identification of the cell proliferation center in oral CIS and dysplasia.     

Phenotypic alterations in Kaposi’s sarcoma cells by antisense reduction of perlecan

Metastasis is a sequence of events including proliferation, migration, adhesion, invasion and subsequent metastatic growth of tumour cells in distant organs. We previously showed that highly metastatic variants of murine melanoma cells express higher levels of the basement membrane proteoglycan perlecan than low or non metastatic variants and expression of an antisense perlecan can reduce metastatic potential. In contrast, antisense expression of perlecan in fibrosarcoma cells was reported to enhance tumorigenesis. To better understand the role of perlecan in angiogenesis we have transfected KS-IMM, an immortalized cell line derived from a human Kaposi s sarcoma, with an antisense perlecan construct and investigated the positive/negative role of perlecan in KS. KS-IMM cells were transfected with either empty vector (neo) or the antisense perlecan construct and clones were isolated. Immuno-blot analysis showed a reduction of perlecan levels in two (AP3 and AP4) isolated clones, in Northern blot analysis endogenous perlecan was undetectable in the AP3 and AP4 clones, while it was present in the neo control clones. AP clones had a reduced migration to HGF in Boyden chambers as compared to neo clones. Proliferation in low serum or serum-free conditions was strongly reduced in the AP clones as compared to the neo control cells. The neotransfected cells showed rapid proliferation in low serum supplemented with HGF and VEGF, while antisense transfected clones showed little response. Finally, AP-trasfected KS-IMM cells had significantly reduced migration to VEGF and HGF with respect to controls. In contrast, when the AP transfected cells were injected in nude mice they paradoxically showed enhanced tumor growth as compared to controls. Our preliminary data indicate that perlecan reduction plays a crucial role on Kaposi s sarcoma cell migration and proliferation in vitro. However, in vivo KS-IMM depleted of perlecan had a growth advantage. A possible hypothesis is that perlecan is necessary for growth of KS-IMM cells in vitro, however its down-regulation might promote angiogenesis through increased angiogenic growth factor diffusion, resulting in enhanced tumor growth in vivo.     

Juvenile traumatic brain injury induces long-term perivascular matrix changes alongside amyloid-beta accumulation

In our juvenile traumatic brain injury (jTBI) model, emergence of cognitive dysfunctions was observed up to 6 months after trauma. Here we hypothesize that early brain injury induces changes in the neurovascular unit (NVU) that would be associated with amyloid-beta (Aβ) accumulation. We investigated NVU changes for up to 6 months in a rat jTBI model, with a focus on the efflux protein P-glycoprotein (P-gp) and on the basement membrane proteins perlecan and fibronectin, all known to be involved in Aβ clearance. Rodent-Aβ staining is present and increased after jTBI around cerebral blood microvessels, and the diameter of those is decreased by 25% and 34% at 2 and 6 months, respectively, without significant angiogenesis. P-glycoprotein staining in endothelium is decreased by 22% and parallels an increase of perlecan and fibronectin staining around cerebral blood vessels. Altogether, these results strongly suggest that the emergence of long-term behavioral dysfunctions observed in rodent jTBI may be related to endothelial remodeling at the blood–brain barrier alongside vascular dysfunction and altered Aβ trafficking. This study shows that it is important to consider jTBI as a vascular disorder with long-term consequences on cognitive functions.     

Searching urinary tumor-associated proteins for bladder transitional cell carcinoma in southwestern Taiwan using gel-based proteomics

Background and purposeWe try to search for specific serum or urinary biomarkers for the early detection, follow-up, and prediction of tumor recurrence, progression, and clinical outcome is a difficult task in individuals with bladder cancer.Materials and methodsIn this study, urinary samples were dialyzed to remove any interfering molecules and concentration by lyophilization. The urinary proteome maps of 10 healthy volunteers and 10 bladder transitional cell carcinoma (BTTC) patients were explored through two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) coupled with mass spectrometry. With no fractionation, the proteome maps acquired in this study likely represented the total urinary proteins.ResultsComparative proteomics indicated that six proteins were down-regulated and five proteins were up- regulated in BTCC patients as compared with normal. The down-regulated spots were identified as human haptoglobin precursor, human heparan sulfate proteoglycan perlecan, inter-alpha-trypsin inhibitor heavy chain H4 precursor, and AMBP protein precursor. The up-regulated spots were identified as peroxiredoxin 2, heparan sulfate proteoglycan perlecan, protease serine 1 fragment and AMBP protein precursor. Most of these de-regulated proteins were extracellular matrix–associated proteins, which may play roles in regulating the immune response, signal transduction and tumor invasions.ConclusionIn this paper, 11 de-regulated proteins were observed in the urinary specimens of BTTC patients from the southwestern coast of Taiwan where Blackfoot disease is endemic and the unusually high incidence of BTTC in this area might attribute to high arsenic content in the drinking water. It is possible that long-term arsenic-induced alteration of these de-regulated proteins, most of which were extracellularmatrix – (ECM) related proteins which may play roles in regulating the immune response, signal transduction and tumor invasions, might be involved in BTTC development in southwestern Taiwan.