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Identification and purification of Ca2+/calmodulin-dependent protein kinase V from human gastric carcinoma
Abstract:
We previously purified a novel Ca2+/calmodulin-dependent protein kinase (CaM kinase) V, which has proven to be a member of the CaM kinase I family. Immunohistochemical staining of surgically-resected specimens from human subjects using specific antibody which reacts with CaM kinases I and V demonstrated heterogeneous distribution of CaM kinase I/V in normal gastric mucosa. The kinase was located mainly at the bottom of foveoral epithelium and in the gastric gland (< 25% immunopositive). In contrast, this kinase was abundant in various types of gastric carcinomas (> 75%), but not in gastric adenomas. Preferential and consistent presence of this kinase was confirmed by immunoblot analysis of gastric carcinoma and human gastric cancer cell lines, Kato-III and MKN-45. CaM kinase I/V was co-purified with CaM kinase II from resected gastric carcinoma using anion-exchange chromatography followed by calmodulin-affinity chromatography. The two kinases were finally separated by HPLC-based gel filtration. Purified CaM kinase I/V from gastric carcinoma did not possess detectable autophosphorylating activity, in contrast to CaM kinase II. The findings suggest CaM kinase I/V may possess abnormal biochemical properties in human gastric carcinoma, and the kinase could participate in cell growth of the carcinoma.
Insights
Calcium/calmodulin-dependent protein kinase (CaM kinase) I/V is abundant in human gastric carcinomas but not adenomas. This kinase may have abnormal properties and contribute to gastric cancer cell growth.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- A novel Ca2+/calmodulin-dependent protein kinase (CaM kinase) V, identified as a CaM kinase I family member, was previously purified.
- CaM kinases play crucial roles in cellular signaling pathways.
Purpose of the Study:
- To investigate the distribution and potential role of CaM kinase I/V in human gastric normal mucosa and gastric carcinoma.
- To analyze the biochemical properties of CaM kinase I/V in gastric cancer.
Main Methods:
- Immunohistochemical staining of human gastric tissues.
- Immunoblot analysis of gastric carcinoma tissues and cell lines (Kato-III, MKN-45).
- Anion-exchange chromatography, calmodulin-affinity chromatography, and HPLC-based gel filtration for kinase purification and separation.
Main Results:
- CaM kinase I/V showed heterogeneous distribution in normal gastric mucosa, primarily in the lower foveolar epithelium and gastric glands.
- The kinase was significantly abundant in various gastric carcinomas (>75%) but absent in gastric adenomas.
- CaM kinase I/V was consistently detected in gastric carcinoma tissues and cell lines.
- Purified CaM kinase I/V from gastric carcinoma lacked detectable autophosphorylating activity, unlike CaM kinase II.
Conclusions:
- CaM kinase I/V exhibits differential expression patterns between normal gastric tissue and gastric carcinoma.
- The kinase may possess altered biochemical properties in gastric carcinoma.
- CaM kinase I/V is a potential participant in the aberrant cell growth characteristic of human gastric carcinoma.