We studied the distribution of the large hyaluronan-binding proteoglycan versican (also known as PG-M) in human adult tissues using affinity-purified polyclonal antibodies that recognize the core protein of the prominent versican splice variants VO and V1. Versican was present in the loose connective tissues of various organs and was often associated with the elastic fiber network. Furthermore, it was localized in most smooth muscle tissues and in fibrous and elastic cartilage. Versican staining was also noted in the central and peripheral nervous system, in the basal layer of the epidermis, and on the luminal surface of some glandular epithelia. In blood vessels, versican was present in all three wall layers of veins and elastic arteries. In muscular arteries the immunoreactivity was normally restricted to the tunica adventitia. However, it appeared in the media and the split elastica interna of atherosclerotically transformed vessel walls. Our survey of the distribution of versican in normal human tissues now forms the basis for extended studies of potentially aberrant versican expression during pathogenic processes.

Stem cell‐like cells have recently been identified in melanoma cell lines, but their relevance for melanoma pathogenesis is controversial. To characterize the stem cell signature of melanoma, expression of stem cell markers BMI‐1 and nestin was studied in 64 cutaneous melanomas, 165 melanoma metastases as well as 53 melanoma cell lines. Stem cell renewal factor BMI‐1 is a transcriptional repressor of the Ink4a/Arf locus encoding p16^ink4a and p14^Arf. Increased nuclear BMI‐1 expression was detectable in 41 of 64 (64%) primary melanomas, 117 of 165 melanoma metastases (71%) and 15 of 53 (28%) melanoma cell lines. High nestin expression was observed in 14 of 56 primary melanomas (25%), 84 of 165 melanoma metastases (50%) and 21 of 53 melanoma cell lines (40%). There was a significant correlation between BMI‐1 and nestin expression in cell lines (p = 0.001) and metastases (p = 0.02). These data indicate that cells in primary melanomas and their metastases may have stem cell properties. Cell lines obtained from melanoma metastases showed a significant higher BMI‐1 expression compared to cell lines from primary melanoma (p = 0.001). Further, primary melanoma lacking lymphatic metastases at presentation (pN0, n = 40) was less frequently BMI‐1 positive than melanomas presenting with lymphatic metastases (pN1; n = 24; 52% versus 83%; p = 0.01). Therefore, BMI‐1 expression appears to induce a metastatic tendency. Because BMI‐1 functions as a transcriptional repressor of the Ink4a/Arf locus, p16^ink4a and p14^Arf expression was also analyzed. A high BMI‐1/low p16^ink4a expression pattern was a significant predictor of metastasis by means of logistic regression analysis (p = 0.005). This suggests that BMI‐1 mediated repression of p16^ink4a may contribute to an increased aggressive behavior of stem cell‐like melanoma cells.

Cyclooxygenase 2 (COX-2) is an inflammation-associated enzyme involved in the pathogenesis of many solid tumors, but little is known about its presence and role in hematologic neoplasms. Multiple myeloma (MM) is known to involve a deregulated cytokine network with secretion of inflammatory mediators. We thus decided to investigate the involvement of COX-2 in this neoplasm. Western blotting (WB) was used to evaluate 142 bone marrow (BM) specimens, including MM and monoclonal gammopathy of undetermined significance (MGUS). Selected cases under-went further evaluation by WB on purified CD138⁺ cells, immunohistochemistry (IC), and real-time polymerase chain reaction (PCR) for mRNA expression. COX-2 was expressed in 11% (2 of 18) of MGUS specimens, 31% (29 of 94) of MM at diagnosis, and 47% (14 of 30) of MM with relapsed/refractory disease. COX-2 positivity was associated with a poor outcome in terms of progression-free (18 vs 36 months; P < .001) and overall survival (28 vs 52 months; P < .05). Real-time PCR showed COX-2 mRNA overexpression. IC and cell separation studies demonstrated COX-2 expression to be restricted to malignant plasma cells. This is the first report of the presence and prognostic role of COX-2 expression in MM. Future studies will assess COX-2 involvement in other hematologic tumors and its potential use as a therapeutic or chemo-preventive target in onco-hematology. (Blood. 2005; 105:4784-4791)