Laminin alpha1 chain in human renal cell carcinomas and integrin-mediated adhesion of renal cell carcinoma cells to human laminin isoforms

Caspase-10, matrix metalloproteinase-9 and total laminin are correlated with the tumor malignancy of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is a common malignant kidney tumor, the pathogenesis of which remains unclear. The aim of the present study was to investigate whether caspase-10, matrix metalloproteinase-9 (MMP-9) and total laminin (LM) were involved into the pathogenesis of ccRCC. The levels of caspase-10, MMP-9 and total LM were analyzed by ELISA in tumor tissues and adjacent non-malignant tissues of 27 patients with ccRCC. The results revealed that caspase-10 levels in the tumor tissues were significantly higher than those in the adjacent non-malignant tissues (P<0.05). The MMP-9 levels in the tumor tissues were significantly lower than those in adjacent non-malignant tissues (P<0.01). The total LM levels in tumor tissues revealed no statistical difference with those in the adjacent non-malignant tissues (P=0.757). Additionally, caspase-10 levels were positively correlated with MMP-9 levels (P<0.001), but negatively correlated with total LM levels (P<0.05) in tumor tissues. Correlation analyses with clinical data of patients with ccRCC, revealed that caspase-10 levels (P<0.05) and MMP-9 levels (P<0.001) in tumor tissues were positively correlated with tumor grades of ccRCC, whereas total LM levels were positively correlated with tumor size (P<0.05). The results of the present study suggested that interactions between caspase-10, MMP-9 and LM are likely involved in the pathogenesis of ccRCC. A deeper understanding of the correlation between caspase-10, MMP-9 and LM would aid the clarification of pathogenesis of ccRCC.

Putative biomarker genes for grading clear cell renal cell carcinoma

OBJECTIVE

The initial objective of this renal cancer study was to identify gene sets in clear cell renal cell carcinoma (ccRCC) to support grading of ccRCC histopathology.

MATERIALS AND METHODS

Preselected ccRCC tumor tissues of grade 1 (G1, n = 14) and grade 3 (G3, n = 15) as well es 14 normal kidney tissues thereof were subjected to microarray expression analysis using Human Genome U133 Plus 2.0 Array. Event ratio scoring, hierarchical clustering and principal component analysis were used to determine gene sets that distinguish expression profiles from normal kidney tissue, G1 and G3 tumor tissues.

RESULTS

An initial set of 73 genes provided seven gene subclusters (SC01 to SC07) that distinguish RNA expression profiles from G1, G3 tumor and normal kidney tissues. A ranked list of 24 genes was determined that separated G1 from G3 tumors in high concordance with histopathological grading confirmed by immunohistochemical analysis of ceruloplasmin protein expression.

CONCLUSION

A final set of 24 genes has been determined awaiting further validation on the RNA as well as on the protein level by studying an additional cohort of ccRCC patients. A reliable separation of G1 and G3 tumor grades will be instrumental to foster and direct the administration of upcoming targeted therapeutics of ccRCC tumors in a more predictive and reliable manner.

Alpha4 chain laminins are widely expressed in renal cell carcinomas and have a de-adhesive function

Laminin (Lm) alpha4 chain, a constituent of Lm-411 and Lm-421, is mainly localized to mesenchyme-derived tissues, and is suggested to have a role in formation and function of endothelium, transmigration of inflammatory cells through endothelium, and invasion of certain tumors. In this study, we evaluated the distribution of alpha4 chain Lms in 33 conventional (clear cell) renal cell carcinomas (RCCs) (31 primary tumors, two metastases), two papillary RCCs, and two oncocytomas by immunohistochemistry. In all tumors, immunoreactivity for Lm alpha4 chain was found in vasculature and stroma. Basement membranes were detected around tumor cell islets in 34/37 tumors. They showed immunoreactivity for Lm alpha4 chain in 28/34 cases. Northern blotting, inhibition of protein secretion with monensin, and immunoprecipitation combined with Western blotting showed that Caki-2, ACHN, and Caki-1 renal carcinoma cell lines produce alpha4 chain Lms. In cell adhesion assay, recombinant human Lm-411 did not promote adhesion of renal carcinoma cells but inhibited adhesion to fibronectin (Fn). In cell migration assay, the cells migrated more on Lm-411 than on Fn. The results suggest that alpha4 chain Lms have a de-adhesive function and could thus play a role in detachment, migration and invasion of renal carcinoma cells in vivo.

CXCR4 chemokine receptor engagement modifies integrin dependent adhesion of renal carcinoma cells

The mechanisms leading to renal cell carcinoma (RCC) metastasis are incompletely understood. Although evidence shows that the chemokine receptor CXCR4 and its ligand CXCL12 may regulate tumor dissemination, their role in RCC is not clearly defined. We examined CXCR4 expression and functionality on RCC cell lines, and explored CXCL12-triggered tumor adhesion to human endothelium (HUVEC) or extracellular matrix proteins. Functional CXCR4 was expressed on A498 tumor cells, enabling them to migrate towards a CXCL12 gradient. CXCR4 engagement by CXCL12 induced elevated cell adhesion to HUVEC, to immobilized fibronectin, laminin or collagen. Anti-CXCR4 antibodies or CXCR4 knock down by siRNA applied prior to CXCL12 stimulation impaired CXCL12-triggered tumor adhesion. However, blocking CXCR4 subsequent to CXCL12 stimulation did not. This pointed to an indirect control of tumor cell adhesion by CXCR4. In fact, CXCR4 engagement by CXCL12 also induced alterations of receptors of the integrin family, notably alpha3, alpha5, beta1 and beta3 subunits, and blocking beta1 integrins with a function-blocking antibody prevented CXCL12-induced A498 adhesion. Focal adhesion kinase (total and activated) and integrin-linked kinase significantly increased in CXCL12-treated A498 cells, accompanied by a distinct up-regulation of ERK1/2, JNK and p38 phosphorylation. Therefore, CXCR4 may be crucial in controlling adhesion of A498 cells via cross talking with integrin receptors. These data show that CXCR4 receptors contribute to RCC dissemination and may provide a novel link between CXCR4 chemokine receptor expression and integrin triggered RCC adhesion to the vascular wall and subendothelial matrix components.

Differential Expression of Laminin Isoforms in Ovarian Epithelial Carcinomas Suggesting Different Origin and Providing Tools for Differential Diagnosis

Immunohistochemistry was used to study the distribution of laminin (Ln) chains, collagen types IV (α 1/2), VII, and XVIII and Lutheran antigen (Lu) in 36 frozen ovarian carcinoma samples. Surface epithelial basement membrane (BM) of the normal ovary showed immunoreactivity for Ln α1, α3-α5, β1-3, γ1, and γ2 chains and type IV and XVIII collagens. Chains of Ln-5 (α3β3γ2) and Ln-10 (α5β1γ1) as well as type IV and XVIII collagens were found in most tumor BMs, but Ln α2 chain and type VII collagen were detected only in few tumors. Contrary to serous tumors, BMs of mucinous carcinomas showed Ln α4 chain, but not Ln α1 and β2 chains. Ln α1 chain was found in most endometrioid carcinomas, whereas chains of Ln-5 were only moderately detectable in comparison with serous and mucinous carcinomas. In the normal ovary, Lu immunoreactivity was confined to basal aspect in the ovarian epithelial cells, but in tumor specimens Lu immunostainings showed variable polarized and nonpolarized patterns. The results suggest that the three types of ovarian carcinoma have distinct differences in their Ln distribution and can be grouped based on their expression pattern. This suggests that they may have histogenetically different precursors and may help to distinguish these tumors from each other.

Progression of malignancy in clear cell renal cell carcinomas

Much progress has recently been obtained in the classification and characterization of RCC by using cytogenetic, gene microarray and proteomic techniques. Pivotal for the understanding of the progression of malignancy of clear cell renal cell carcinomas are findings connecting its biology to inactivation of the von Hippel-Lindau tumour suppressor gene product (VHLp), found in most CC-RCCs. Disruption of VHLp function appears to be involved in altered cell cycle control, resistance to hypoxia, hyperangiogenesis and changes in the organization of cytoskeletal and extracellular matrix proteins in RCC. These changes are reflected in the overexpression of the vascular endothelial growth factor (VEGF) and the subunits of hypoxia-inducible factor (HIF), and other angiogenetic and metastasis-promoting factors. Other changes related to progression of malignancy in RCC are the upregulation of proinflammatory cytokines and changes in cell adhesion proteins.