Abnormal distribution of collagen type IV in extrahepatic bile duct carcinoma

Hepatic myofibroblasts promote the progression of human cholangiocarcinoma through activation of epidermal growth factor receptor

Intrahepatic cholangiocarcinoma (CCA) is characterized by an abundant desmoplastic environment. Poor prognosis of CCA has been associated with the presence of alpha-smooth muscle actin (α-SMA)-positive myofibroblasts (MFs) in the stroma and with the sustained activation of the epidermal growth factor receptor (EGFR) in tumor cells. Among EGFR ligands, heparin-binding epidermal growth factor (HB-EGF) has emerged as a paracrine factor that contributes to intercellular communications between MFs and tumor cells in several cancers. This study was designed to test whether hepatic MFs contributed to CCA progression through EGFR signaling. The interplay between CCA cells and hepatic MFs was examined first in vivo, using subcutaneous xenografts into immunocompromised mice. In these experiments, cotransplantation of CCA cells with human liver myofibroblasts (HLMFs) increased tumor incidence, size, and metastatic dissemination of tumors. These effects were abolished by gefitinib, an EGFR tyrosine kinase inhibitor. Immunohistochemical analyses of human CCA tissues showed that stromal MFs expressed HB-EGF, whereas EGFR was detected in cancer cells. In vitro, HLMFs produced HB-EGF and their conditioned media induced EGFR activation and promoted disruption of adherens junctions, migratory and invasive properties in CCA cells. These effects were abolished in the presence of gefitinib or HB-EGF-neutralizing antibody. We also showed that CCA cells produced transforming growth factor beta 1, which, in turn, induced HB-EGF expression in HLMFs.

CONCLUSION

A reciprocal cross-talk between CCA cells and myofibroblasts through the HB-EGF/EGFR axis contributes to CCA progression.

Type IV Collagen Immunostaining Is a Simple, Reliable Diagnostic Tool for Distinguishing Between Adenomatous and Normal Pituitary Glands

Context.—Pituitary adenomas are clinically diagnosed based on radiologic studies and/or secondary effects of hormone production. Definitive pathologic identification relies on immunohistochemical detection of a clonal population of hormone-producing cells. However, not all adenomas secrete hormones, so performing a battery of stains is inefficient. Reports have shown decreased type IV collagen in the stroma of other epithelial tumors.

Objective.—To validate type IV collagen immunohistochemistry as a diagnostic method.

Design.—We immunostained 27 adenomas and 19 normal pituitaries. The areas with the sparsest type IV collagen fibers were viewed at 3 magnifications (×10, ×20, and ×40 objectives), counting 1, 3, or 10 microscopic fields. A field was scored as “traversable” if a path existed from any point on the periphery of the field to a point on the approximately opposite periphery that did not cross any stained fibers. Results were compared with reticulin staining and to the existing diagnosis previously determined by histology, hormone immunostaining, and clinical correlation.

Results.—Adenomas have less type IV collagen in their basement membranes, leading to sparser, trabecular staining in neoplasms versus a more rigid meshwork pattern in normal glands. One might envision the stained fibers as maze walls—one can traverse medium-powered fields in an adenoma, but one hits dead ends and gets trapped in those of a normal gland. Finding a single representative ×10 field to be traversable was 97.5% sensitive and 96.5% specific for an adenoma. Reticulin staining yielded identical results.

Conclusions.—Type IV collagen immunostaining is a simple and reliable method of diagnosing pituitary adenomas.

Leukocyte, rather than tumor-produced SPARC, determines stroma and collagen type IV deposition in mammary carcinoma

Secreted protein, acidic and rich in cysteine (SPARC), also known as osteonectin or BM-40, is a Ca²⁺-binding matricellular glycoprotein involved in development, wound healing, and neoplasia. However, the role of SPARC in tumors is ill defined mostly because it is expressed by both tumor and stromal cells, especially inflammatory cells. We analyzed the respective roles of host- and tumor-derived SPARC in wild-type and congenic SPARC knockout (SPARC^−/−) mice on a BALB/c genetic background injected into the mammary fat pad with SPARC-producing mammary carcinoma cells derived from c-erB2 transgenic BALB/c mice. Reduced tumor growth but massive parenchyma infiltration, with large areas of necrosis and impaired vascularization were observed in SPARC^−/− mice. Immunohistochemical analysis showed a defect in collagen type IV deposition in the stroma of lobular tumors from SPARC^−/− mice. Chimeric mice expressing SPARC only in bone marrow–derived cells were able to organize peritumoral and perilobular stroma, whereas reciprocal chimeras transplanted with bone marrow from SPARC^−/− mice developed tumors with less defined lobular structures, lacking assembled collagen type IV and with a parenchyma heavily infiltrated by leukocytes. Together, the data indicate that SPARC produced by host leukocytes, rather than the tumor, determines the assembly and function of tumor-associated stroma through the organization of collagen type IV.

The prognostic significance of type IV collagen expression in colorectal carcinomas

BACKGROUND: Breakdown of basement membrane is believed to be an essential step for tumor invasion and metastasis. The interaction between tumor cells and extracellular matrix can also result in induction of basement membrane synthesis by tumor and stromal cells. The aim of this study was to investigate distribution patterns of type IV collagen expression at the basement membrane in the tumor tissue of colorectal carcinomas by immunohistochemical staining. The degree of expression of type IV collagen correlated with classical clinicopathologic prognostic factors and their potential relationship with patients' prognosis. PATIENTS AND METHODS: This study included 40 patients who underwent curative resection of colorectal cancer at the Department of Surgery in the General Hospital Senta with complete follow-up for 5 years or until death. The identification of basement membrane was performed immunohistochemically using monoclonal antibodies to collagen IV. The basement membrane synthesis at the invasive front of colorectal cancer was semiquantitatively assessed as mild, moderate or severe. RESULTS: The deposition of basement membrane type of collagen IV had a statistically significant correlation with the stage of disease and histological grade of tumor with tendency of lesser synthesis of basement membrane in the advanced stage of disease and poorer histological grade of tumor. There were no significant correlations between intratumoral basement membrane synthesis and sex and age of patients, and localization and histological type of tumor. Five-year survival rates in patients with mild synthesis of basement membrane in colorectal tumor were significantly lower than in patients with severe expression of basement membrane. The basement membrane synthesis in colorectal cancer was a prognostic factor with significance behind stage of disease and histological grade of tumor by univariate Cox hazard-model. Multivariate Cox analysis verified that explicit synthesis of basement membrane showed a trend toward better prognosis, but it was not statistically significant. CONCLUSION Immunohistochemical staining for type IV collagen is an important additional technique with prognostic value.

Critical role of type IV collagens in the growth of bile duct carcinoma. In vivo and in vitro studies

Most extrahepatic bile duct carcinomas (EBDC) are characterized by a striking stromal response (desmoplasia). Our previous studies showed deposition of type IV collagen in the desmoplastic stroma beyond the basement membrane. Although type IV collagen is expressed in EBDC, little is known about the pattern of deposition in tumor stroma and how this matrix component influences the behavior of tumor cells. With the progression of desmoplasia in EBDC, different changes occurred in the quantity and localization of type IV collagen from that of type I collagen. Type I collagen was diffusely distributed in the stroma and appeared to be concentrated in the center of the tumors. In contrast, type IV collagen was deposited in the interstitium alongside carcinoma cells at the tumors' periphery. Weak or no type IV collagen deposition was detected in the more central portion of the tumors containing sclerotic collagens. To investigate the role of stromal type IV collagen in tumor cell proliferation, EBDC cell lines were cultured in a three-dimensional matrix containing varying compositions of type I collagen and type IV collagen. They were also assayed for cell adhesion and migration using in vitro models. Type IV collagen more extensively stimulated tumor cell proliferation, adhesion and migration in a dose-dependent manner than did type I collagen. All of these results suggest that modified tumor stroma with the presence of type IV collagen in EBDC provides a better environment for tumor growth and invasion.

Subcutaneous adipocytes promote the differentiation of squamous cell carcinoma cell line (DJM-1) in collagen gel matrix culture

Cancer cell-stromal cell interaction plays a crucial role in the malignant growth of cancer cells. In the skin, the main stromal cell types consist of dermal fibroblasts and subcutaneous adipocytes. Fibroblasts are shown to promote the invasive growth of various cancer cell types. The interaction between cancer cells and stromal adipocytes, however, has not been sufficiently studied even in cutaneous carcinoma. To address the effects of adipocytes on the biologic behavior of cancer cells, we examined the growth and differentiation of a squamous cell carcinoma cell line of the skin (DJM-1), using a three-dimensional collagen gel matrix culture with a cutaneous environmental factor, air exposure. The growth was estimated by the uptake of bromodeoxy-uridine (BrdU) for 24 h. The BrdU indices of DJM-1 cells in stromal-cell-free, fibroblast-containing, and adipocyte- containing conditions were 19.7 +/- 1.9%, 19.8 +/- 2.8%, and 4.7 +/- 1.4%, respectively, whereas the BrdU index on the gel containing both fibroblasts and adipocytes was 10.4 +/- 3.3%. In terms of differentiation, DJM-1 cells cocultured with adipocytes constructed the best-organized stratified layer with a cornified-like structure in all conditions above. The differentiation markers involucrin and cytokeratin 10 were immunohistochemically detected in this structure of DJM-1 cells. Adipocyte-induced phenomena were not affected distinctively by air exposure. These results indicate that adipocytes, but not fibroblasts, promote the differentiation of squamous cell carcinoma cells (DJM-1) and inhibit their growth. These adipocyte-induced phenomena were not completely inhibited by fibroblasts. In conclusion, we suggest that stromal adipocytes may be involved in the differentiating mechanisms of cutaneous carcinoma cells.