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Caspase 7 downregulation as an immunohistochemical marker of colonic carcinoma
F Palmerini1, E Devilard, A Jarry
1INSERM U 119; Department of Pathology, Institut Paoli-Calmettes, IFR 57 and Université de la Méditerranée, Marseille, France.
Abstract:
Caspases play a crucial role as apoptotic effectors; their potential implication in tumorigenesis remains to be clarified. We investigated the expression and function of caspases 7, 8, and 9 in colon cancer tissues and cell lines. Immunohistochemistry (IHC) showed downregulation of caspase 7 (22 of 26 cases) and caspase 9 (12 of 26 cases) in colonic cancer samples compared with normal mucosa on the same tissue section. Caspase 8 expression was unchanged or slightly upregulated (19 of 27 cases). The combination of IHC and Western blot analysis showed expression of the proforms of caspases 7, 8, and 9 in HT29-19A and HT29-16E colonic carcinoma cell lines. Apoptosis could be induced by staurosporine in both HT29 cell lines, with a sensitivity similar to that of the HGT cell line, but lower than that of the DAUDI cell line. Apoptosis induction in HT29 cells was concomitant with processing of caspases 3, 7, 8, and 9 and was inhibited by the caspase inhibitor ZVAD. Our data show that (1) human colon cancer cells downregulate caspase 7 and, to a smaller extent, caspase 9 in vivo and (2) in vitro staurosporine-induced apoptosis of colonic cancer cells involves caspases 7 and 9. Caspase 7 deficiency thus appears as a new immunohistochemical marker of colonic neoplasia; its correction represents a potential basis for new therapies.
Insights
Colon cancer cells show reduced levels of caspase 7 and caspase 9. Restoring caspase 7 function may offer a new therapeutic strategy for colon neoplasia.
Area of Science:
- Molecular Biology
- Oncology
- Cell Death Research
Background:
- Caspases are key executioners of apoptosis.
- Their role in cancer development, particularly colon cancer, requires further investigation.
- Understanding caspase expression and function is crucial for cancer therapy.
Purpose of the Study:
- To investigate the expression and functional role of caspases 7, 8, and 9 in colon cancer.
- To determine if caspase expression differs between colon cancer tissues and normal tissues.
- To explore the involvement of caspases in apoptosis induction in colon cancer cell lines.
Main Methods:
- Immunohistochemistry (IHC) was used to assess caspase expression in colon cancer tissues and adjacent normal mucosa.
- Western blot analysis was performed on colon cancer cell lines (HT29-19A, HT29-16E).
- Apoptosis was induced using staurosporine, and caspase processing was analyzed in the presence and absence of a caspase inhibitor (ZVAD).
Main Results:
- Downregulation of caspase 7 and caspase 9 was observed in colon cancer tissues compared to normal mucosa.
- Caspase 8 expression remained largely unchanged or was slightly upregulated.
- Staurosporine-induced apoptosis in colon cancer cell lines involved the processing of caspases 3, 7, 8, and 9, and was sensitive to caspase inhibition.
Conclusions:
- Human colon cancer cells exhibit reduced expression of caspase 7 and, to a lesser extent, caspase 9.
- In vitro apoptosis induction in colon cancer cells is mediated by caspases 7 and 9.
- Caspase 7 deficiency may serve as a novel immunohistochemical marker for colonic neoplasia, and its restoration could be a therapeutic target.
