Keratin and carcinoembryonic antigen (CEA) in human melanoma cells

The effect of a novel frizzled 8-related antiproliferative factor on in vitro carcinoma and melanoma cell proliferation and invasion

Antiproliferative factor (APF) is a potent frizzled protein 8-related sialoglycopeptide inhibitor of bladder epithelial cell proliferation that mediates its activity by binding to cytoskeletal associated protein 4 in the cell membrane. Synthetic asialylated APF (as-APF) (Galβ1-3GalNAcα-O-TVPAAVVVA) was previously shown to inhibit both normal bladder epithelial as well as T24 bladder carcinoma cell proliferation and heparin-binding epidermal growth factor-like growth factor (HB-EGF) production at low nanomolar concentrations, and an L: -pipecolic acid derivative (Galβ1-3GalNAcα-O-TV-pipecolic acid-AAVVVA) was also shown to inhibit normal bladder epithelial cell proliferation. To better determine their spectrum of activity, we measured the effects of these APF derivatives on the proliferation of cells derived from additional urologic carcinomas (bladder and kidney), non-urologic carcinomas (ovary, lung, colon, pancreas, and breast), and melanomas using a (3)H-thymidine incorporation assay. We also measured the effects of as-APF on cell HB-EGF and matrix metalloproteinase (MMP2) secretion plus cell invasion, using qRT-PCR, Western blot and an in vitro invasion assay. L: -pipecolic acid as-APF and/or as-APF significantly inhibited proliferation of each cell line in a dose-dependent manner with IC(50)'s in the nanomolar range, regardless of tissue origin, cell type (carcinoma vs. melanoma), or p53 or ras mutation status. as-APF also inhibited HB-EGF and MMP2 production plus in vitro invasion of tested bladder, kidney, breast, lung, and melanoma tumor cell lines, in a dose-dependent manner (IC(50) = 1-100 nM). Synthetic APF derivatives are potent inhibitors of urologic and non-urologic carcinoma plus melanoma cell proliferation, MMP2 production, and invasion, and may be useful for development as adjunctive antitumor therapy(ies).

Keratin 16 Expression in Epidermal Melanocytes of Normal Human Skin

Although the prevailing dogma states that keratin filaments are the hallmark of keratinocytes and other epithelial cells, recent publications suggest that they may be expressed by a variety of normal and malignant cells of different embryonic origin. Keratin expression has been reported in fibroblasts and endothelial cells as well as in various sarcomas. Also, some human melanomas express keratins in addition to the traditional diagnostic markers of differentiation, such as S-100 and melanocyte-specific antigens. Many studies have shown that cultured cells obtained from various melanomas express keratin. Most recently, keratin expression has also been shown in cultured melanocytes of normal skin. We now report that normal human melanocytes in vivo express keratin 16 (K16) but not keratins 1, 5, 8, 10, 14, or even keratin 6, the type II partner that is normally expressed with K16 in keratinocytes. Similarly, melanocytes in vitro express K16 but not K6. Keratin 16 expression in vivo was present in basal melanocytes in specimens derived from donors (0-77 years) and from different anatomic locations, suggesting that keratin 16 is constitutively expressed by all melanocytes. It appears that keratin expression may be more prevalent than previously assumed, and that these cytoskeletal filaments may play important roles in tissues and cells other than epithelia.

Electron microscopy in tumor diagnosis: indications for its use in the immunohistochemical era

The electron microscope reveals much more information on tumor cell structure than can be obtained with the light microscope, and some of the data are useful in diagnostic studies. In this review, major contributions of electron microscopy in the main tumor categories are discussed. To select between immunocytochemistry and electron microscopy, the probable contributions of each in the context of the particular case must be assessed. Usually, electron microscopy will only be requested after a battery of immunostaining procedures has been performed and found to be insufficient, but there are occasions when ulstrastructural study is logically the first choice after routine light microscopy. It is worth taking tissue for possible electron microscopy from any tumor that is known or anticipated to be a diagnostic problem.

Keratin expression and its significance in five cultured melanoma cell lines derived from primary, recurrent and metastasized melanomas

With the exception of two cases, keratin is not expressed in cultured human melanoma cells. Using 2D-PAGE, immunological and electron microscopic analyses, we found keratin subunits in five established cultured cell lines derived from primary, recurrent and metastasized melanomas. The keratin subunits were composed of K1, K5, K10, K14, K15 and K18 in all cell lines examined, together with vimentin. In addition, K8, K16 and K18 expression were demonstrated in recurrent and metastasized cell lines. The results of the present and our previous study [Katagata Y, et al. J Dermatol Sci 1996;13:219-227] indicate that expression of keratin in melanoma cells may be a universal phenomenon. A specific increase in the proportion of K5 among the keratin subunits was suggestive of the nature of melanoma cells. Moreover, we detected two polypeptides that migrated on 2D-PAGE at positions which did not correspond to those of any keratin subunit. The amino acid sequences of these two polypeptides were determined; one was the human ATP synthase alpha-chain but the other did not match any known polypeptide in our homology search.

Identification of K1/K10 and K5/K14 keratin pairs in human melanoma cell lines

Keratin expression in cultured malignant melanoma cells has been studied only rarely. Moreover, no studies have reported of universality of keratin expression in human malignant melanoma cells. In this study, therefore, we analyzed keratin expression in eight cell lines. Using a low-salt aqueous solution without high salt and Triton X-100, as a washing buffer for keratin extraction, followed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and immunological analysis, we demonstrated keratin expression in all eight human malignant melanoma cell lines. The keratin polypeptide expressions common to all melanoma cells were K1, K5, K10 and K14. In addition, K8, K13, K17 and K18, respectively, were detected in individual cells. A measure of keratin expression universality in malignant melanoma cells may have implications regarding their invasive and metastatic behaviors, co-expressed with vimentin.

Classification of CEA-related positivity in primary and metastatic malignant melanoma

Using a panel of antibodies to carcinoembryonic antigen (CEA), in paraffin-processed biopsy material patchy, predominantly membranous positivity was seen on tumour cells in 70 per cent of cases of superficial spreading melanoma, 60 per cent of nodular melanomas, and 75 per cent of secondary deposits studied with unabsorbed polyclonal anti-CEA only. No staining was seen using monoclonal anti-CEAs. Localization of CEA to the cell membrane was confirmed with confocal microscopy. Immunoblotting of fresh frozen material detected CEA of around 180 kD in both primary and metastatic melanomas migrating with an apparent molecular weight of between 150 and 200 kD, indicating variable glycosylation of the protein. Recognition of an adhesive role for CEA with roles in immunolocalization and immunotherapy emphasizes the importance of more precise classification of CEA-related positivity in human tumours.

The use of immunomorphology to differentiate choroid plexus tumors from metastatic carcinomas

BACKGROUND

The histologic and immunohistologic differential diagnosis of choroid plexus papillomas/plexus carcinomas (PP/PC) versus metastatic carcinoma in the brain is problematic.

METHODS

Thirty-four choroid PP/PC from 28 patients, 5 normal choroid plexus, and 45 cerebral metastatic carcinomas were immunohistochemically examined with the monoclonal anti-epithelial noncytokeratin antibodies HEA 125 and Ber EP4 using the alkaline phosphatase anti-alkaline phosphatase (APAAP) method.

RESULTS

Normal choroid plexus epithelium was consistently negative. Sections from PP/PC of 3 of 28 patients demonstrated immunoreactivity for these antibodies. In contrast, 43 of 45 cerebral metastatic carcinomas displayed positive immunostaining for HEA 125, and 44 of these 45 carcinomas were positive for Ber EP4. Thus, sensitivity was higher for these antibodies than for the monoclonal anticytokeratin antibody KL1 (41/45). All three HEA 125/Ber EP4-positive PP/PC contained periodic acid-Schiff (PAS)-positive, tall columnar tumor cells. The intensively HEA 125, Ber EP4, and PAS-positive PP/PC were interpreted as possible transitional forms of the mucus-secreting and acinar PP/PC:

CONCLUSIONS

Despite this restriction, the authors proposed the application of HEA 125 and Ber EP4 as a reliable tool in the differential diagnosis of PP/PC versus metastatic carcinoma, especially in combination with glial fibrillary acid protein and transthyretin. Currently, all HEA 125/Ber EP4-positive PP/PC in patients older than 20 years proved to be metastatic carcinomas during their clinical course.

An immunophenotypic survey of malignant melanomas

An immunohistochemical study of 106 malignant melanoma specimens from 59 patients, using formalin-fixed, paraffin-embedded material, is reported. Negativity for HMB-45 was seen in 11% of specimens. The rate of positivity with CAM 5.2 was 7%. One specimen showed alpha-smooth muscle actin (alpha SMA) positivity. For 11 of the 12 cases in which anomalous immunophenotypes were seen, multiple specimens were available; nine of these showed evidence of an alteration in the immunophenotype between specimens. Comparing the primary tumours with local recurrences and metastases, there was, variously, loss of HMB-45, S-100 protein and NKI/C3 positivity, and acquisition of CAM 5.2 and alpha SMA positivity. In some cases, the change of immunophenotype appeared to occur in a single step. However, one case with six consecutive specimens showed evidence of progressive loss of HMB-45, S-100 protein and NKI/C3 with concomitant gain of CAM 5.2 staining. The implications for the use of immunophenotyping in diagnostic practice are discussed.