ALG-2 was isolated in a screen for proteins involved in programmed cell death and is the first Ca(2+)-binding protein found to be directly involved in apoptosis. We have generated polyclonal antibodies that are suitable for detecting ALG-2 using different immunological methods. Three commercial antibodies against ALG-2 did neither detect mouse recombinant ALG-2 nor endogenous ALG-2 in Jurkat cell lysates, whereas our own affinity-purified antibody recognized recombinant as well as endogenous ALG-2. The specificity of the antibody was shown by preabsorbtion experiments and on ALG-2-deficient cells using Western blot analysis and immunohistochemistry. Western blot analysis of 15 different adult mouse tissues demonstrated that ALG-2 is ubiquitously expressed. We found that ALG-2 was more than threefold overexpressed in rat liver hepatoma compared to normal rat liver using Western blot analysis, a result confirmed by immunohistochemical analysis. Staining of four different lung cancer tissue microarrays including specimens of 263 patients showed that ALG-2 is mainly localized to epithelial cells and significantly up-regulated in small-cell lung cancers and in non-small-cell lung cancers. Our results lead to the conclusion that ALG-2 beside its known proapoptotic functions may be a player in survival pathways.
The apoptosis linked gene-2 (ALG-2), discovered as a proapoptotic calcium binding protein, has recently been found upregulated in lung cancer tissue indicating that this protein may play a role in the pathology of cancer cells and/or may be a tumor marker. Using immunohistochemistry on tissue microarrays we analysed the expression of ALG-2 in 7371 tumor tissue samples of various origin as well as in 749 normal tissue samples. Most notably, ALG-2 was upregulated in mesenchymal tumors. No correlation was found between ALG-2 staining intensity and survival of patients with lung, breast or colon cancer. siRNA mediated ALG-2 downregulation led to a significant reduction in viability of HeLa cells indicating that ALG-2 may contribute to tumor development and expansion.
García-Caballero T, Grabau D, Green A R, Gregory J, Schad A, Kohlwes E, Ellis I O, Watts S & Mollerup J (2010) Histopathology56, 472–480 Determination of HER2 amplification in primary breast cancer using dual-colour chromogenic in situ hybridization is comparable to fluorescence in situ hybridization: a European multicentre study involving 168 specimensAims:Fluorescence in situ hybridization (FISH) can be used to reveal several genomic imbalances relevant to proper cancer diagnosis and to the correct treatment regime. However, FISH requires expensive and advanced fluorescence microscopes in addition to expertise in fluorescence microscopy. To determine whether a newly developed dual-colour chromogenic in situ hybridization (CISH) method is a suitable alternative to FISH, we analysed the human epidermal growth factor receptor 2 gene (HER2) amplification level of 168 breast cancer specimens using dual-colour CISH and FISH and compared the results.Methods and results:We found 100% agreement between HER2 status determined by FISH and dual-colour CISH. Furthermore, we observed that the time used to score slides was significantly reduced by 28% in dual-colour CISH compared with the FISH protocol. Concordance between HER2 protein status and dual-colour CISH or FISH was equally good with an overall agreement of 96.8%. Correlation between the HER2/centromere 17 gene ratios obtained with dual-colour CISH and FISH was highly significant with an overall correlation coefficient (ρ) of 0.96.Conclusions:We conclude that dual-colour CISH and bright field microscopy are excellent alternatives to FISH when analysing the HER2 status of primary breast cancer.
ALG-2 was originally discovered as a pro-apoptotic protein in a genetic screen. Due to its ability to bind calcium with high affinity it was postulated to provide a link between the known effect of calcium in programmed cell death and the molecular death execution machinery. This review article discusses the current knowledge on the structure and potential function of this protein. Several putative binding partners of ALG-2 have been identified hinting to functions of ALG-2 in apoptosis and possibly also in proliferation, endocytosis and transcriptional regulation during development. Gene deletion of the well conserved ALG-2 locus in several genetic model organisms has so far not provided insights into functions and signaling pathways with ALG-2 involvement. Special focus is given to controversial data on expression and localization of ALG-2, which is mainly caused by the use of ALG-2 antibodies with different specificities.
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