Anti-Cytokeratin 8 Anticorps [C-43] (A86582)

CARM1 and PRMT1 are 2 Protein Arginine Methyl Transferases (PRMT) dysregulated in cancer. CARM1 function is contradictory and depicted as facilitating proliferation or differentiation. PRMT1 is required for cell proliferation. CARM1 and PRMT1 cooperate for gene regulation. We report that CARM1 and PRMT1 are significantly overexpressed in 60 patients with Non-Small Cell Lung Carcinomas (NSCLC). CARM1 and PRMT1 correlated in healthy but not tumor tissue. Their levels of expression in tumor tissue were proportional to their levels of expression in the counterpart healthy tissue. Only CARM1 expression was found to be correlated with tumor differentiation and neither CARM1 nor PRMT1 expression was correlated with survival. Accordingly, CARM1 and PRMT1 are overexpressed in 2 NSCLC cell lines, A549 and H1299. Targeting PRMT1 with siRNA reduced proliferation, by decreasing cell growth and inhibiting soft agar colony formation, and promoted differentiation, by increasing the epithelial markers cytokeratin 7 and 8 and decreasing Neuromedin B receptor, which binds a mitogenic factor. siCARM1 yielded similar consequences but the conditions with siCARM1 reflected inhibition of both CARM1 and PRMT1. Together these results suggest that CARM1 and PRMT1 are involved in proliferation in lung cancer with no hierarchy of one protein over the other. The fact that CARM1 targeting suppresses PRMT1 in addition to CARM1 reinforces the functional importance of CARM1/PRMT1 interaction.

We analysed the involvement of proteases during taxol-mediated cell death of human A549 non-small-cell lung carcinoma cells using a proteomics approach that specifically targets protein N termini and further detects newly formed N termini that are the result of protein processing. Our analysis revealed 27 protease-mediated cleavages, which we divided in sites C-terminal to aspartic acid (Asp) and sites C-terminal to non-Asp residues, as the result of caspase and non-caspase protease activities, respectively. Remarkably, some of the former were insensitive to potent pancaspase inhibitors, and we therefore suggest that previous inhibitor-based studies that report on the caspase-independent nature of taxol-induced cell death should be judged with care. Furthermore, many of the sites C-terminal to non-Asp residues were also uniquely observed in a model of cytotoxic granule-mediated cell death and/or found by in vitro cataloging human mu-calpain substrates using a similar proteomics technique. This thus raises the hypothesis that killing tumor cells by chemotherapy or by immune cells holds similar non-Asp-specific proteolytic components with strong indications to calpain activity.

A series of 14 new mouse monoclonal antibodies (MAbs) to keratins is described and the data suggesting their potential value in the differential diagnosis of human tumours are reported. The specificities of individual MAbs of the 'C-series' presented here range from monospecificity for keratin No. 7 (MAbs C-18, C-35, C-62, and C-68), keratin No. 8 (MAbs C-15, C-43, and C-15), and keratin No. 18 (MAbs C-04 and C-08) up to the broadly reacting 'pan-keratin' MAb C-11, with the target epitopes of the remaining four MAbs being shared by different pairs of keratin polypeptides. The results of the biochemical characterization of the MAbs, together with their immunohistochemical staining patterns on frozen as well as on paraffin sections of normal human tissues, suggest that they represent a significant contribution to the growing list of anti-keratin MAbs applicable in both research and routine diagnostic pathology. The immunohistochemical examination of a wide range of human neoplasms with the new MAbs not only confirmed their value in making distinctions between carcinomas, on the one hand, and lymphomas, and gliomas, on the other, but also verified the possibility of more subtle subdivisions within the group of adenocarcinomas and their metastases. Furthermore, the identification of small subsets of breast carcinomas with decreased levels or apparent loss of the keratin No. 7 polypeptide and some cases of stomach carcinoma with apparently induced expression of this keratin suggests that such 'exceptions' must be considered when using keratin spectra as one of the criteria in differential diagnosis.