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Type I and II cyclic adenosine 3':5'-monophosphate-dependent protein kinase in human gastric mucosa and carcinomas
Abstract:
Cyclic adenosine 3':5'-monophosphate (cAMP)-dependent and cAMP-independent protein kinase activity and the isoenzyme pattern of cAMP-dependent protein kinase were compared in tissues from human nonneoplastic gastric mucosa, 11 human gastric carcinomas, and 2 xenotransplantable human gastric carcinomas (SC-6-JCK and St-15). No difference in total protein kinase activity could be observed between nonneoplastic gastric mucosa and gastric carcinomas. According to diethylaminoethyl cellulose column chromatography, the isoenzyme pattern of the nonneoplastic gastric mucosa was the same in both the gastric fundus and the antrum, and the activity ratio of type II to type I was 5.01. In gastric carcinomas, the elevation of type I was detected independently of the histological type. In xenotransplantable human gastric carcinomas in nude mice, type I isoenzyme was significantly elevated. The activity ratio of type II to type I was 1.70 in SC-6-JCK carcinomas and 1.81 in St-15 carcinomas, respectively. These results suggest that type I cAMP-dependent protein kinase activity in the stomach may be a biochemical marker for malignant transformation and transplantability of gastric tumors.
Insights
Altered cyclic adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase activity, specifically elevated type I isoenzyme, may indicate malignant transformation and transplantability in gastric tumors. This finding offers a potential biochemical marker for stomach cancer progression.
Area of Science:
- Biochemistry
- Oncology
- Molecular Biology
Background:
- Protein kinases play crucial roles in cellular signaling pathways.
- Cyclic adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase (PKA) is a key regulator of various cellular processes.
- Alterations in PKA isoenzyme patterns have been implicated in cancer development.
Purpose of the Study:
- To investigate the activity and isoenzyme patterns of cAMP-dependent and cAMP-independent protein kinases in human gastric tissues.
- To compare these patterns between nonneoplastic gastric mucosa, gastric carcinomas, and xenotransplantable gastric tumors.
- To identify potential biochemical markers for gastric cancer malignancy and transplantability.
Main Methods:
- Tissue samples from human nonneoplastic gastric mucosa, gastric carcinomas, and xenotransplantable gastric carcinomas were analyzed.
- Protein kinase activity was measured.
- Isoenzyme patterns of cAMP-dependent protein kinase were determined using diethylaminoethyl cellulose column chromatography.
Main Results:
- Total protein kinase activity showed no significant difference between nonneoplastic mucosa and gastric carcinomas.
- The isoenzyme pattern of nonneoplastic gastric mucosa exhibited a type II to type I activity ratio of 5.01.
- Gastric carcinomas displayed an elevation in type I isoenzyme, with ratios of 1.70 and 1.81 in xenotransplantable tumors.
Conclusions:
- Type I cAMP-dependent protein kinase activity is significantly elevated in gastric carcinomas.
- The elevated type I isoenzyme may serve as a biochemical marker for malignant transformation of gastric tumors.
- This isoenzyme alteration is also associated with the transplantability of gastric tumors, as observed in xenotransplant models.