ABSTRACT
AIM: To explore whether antisense blocking of protein kinase C alpha (PKCalpha) would reverse multi-drug resistance (MDR) in the vincristine (VCR)-resistant human gastric cancer cell line SGC7901/VCR. METHODS: SGC7901/VCR cells expressing antisense PKCalpha, SGC7901/VCR/aPKC, were established by transfection with a recombinant plasmid reversely inserted with PKCalpha cDNA. Empty vector (PCI-neo)-transfected cell clones, SGC7901/VCR/neo, served as the control. Western blot method was used to detect PKCalpha content in SGC7901, SGC7901/VCR, SGC7901/VCR/neo and SGC7901/VCR/aPKC cells, using PKCalpha-specific antibody. The sensitivity of SGC7901, SGC7901/VCR, SGC7901/VCR/neo and SGC7901/VCR/aPKC cells to doxorubicin (DOX) in vitro was determined by MTT assay. The uptake of DOX in these cells was detected with fluorescence spectrophotometer. RESULTS: Western blot analysis showed that the PKCalpha protein level was about 8.7-fold higher in SGC7901/VCR cells than that in SGC7901 cells, whereas the protein expression of PKCalpha was reduced by 78% in SGC7901/VCR/aPKC cells when compared with the SGC7901/VCR cells. SGC7901/VCR/aPKC cells had a 4.2-fold increase in DOX cytotoxicity, accompanied by a 1.7-fold increase of DOX accumulation in comparison with SGC7901/VCR cells. CONCLUSION: PKCalpha positively regulates MDR in SGC7901 cells, and inhibition of PKCalpha can partially attenuate MDR in human gastric cancer cells.
Subject(s)
Cell Line, Tumor , Doxorubicin/pharmacology , Protein Kinase C-alpha/genetics , Cell Survival/drug effects , DNA, Complementary/genetics , DNA, Neoplasm/genetics , Doxorubicin/pharmacokinetics , Drug Resistance, Multiple , Drug Resistance, Neoplasm , Humans , Oligonucleotides, Antisense , Protein Kinase C-alpha/antagonists & inhibitors , Protein Kinase C-alpha/metabolism , Restriction Mapping , Stomach Neoplasms/drug therapy , Stomach Neoplasms/enzymology , Stomach Neoplasms/pathology , Vincristine/pharmacologyABSTRACT
AIM: To analyze expression of ATP7B in gastric cardiac adenocarcinomas, its clinicopathologic significance, in comparison with distal gastric adenocarcinomas. METHODS: Immunohistochemical avidin-biotin peroxidase complex method was applied to detect the expression of ATP7B in 49 cases of cardiac carcinomas, the corresponding adjacent non-neoplastic epithelium and 55 cases of distal gastric carcinomas. RESULTS: The proportion of ATP7B positive samples in gastric cardiac carcinomas (51.0%, 25 of 49) was significantly higher than that in the corresponding adjacent non-neoplastic epithelium (22.4%, 11 of 49) (P = 0.003). ATP7B expression in poorly differentiated gastric cardiac carcinomas was significantly higher than that in well/moderately differentiated gastric cardiac carcinomas (P = 0.030). ATP7B expression in gastric cardiac carcinomas was independent of age, tumor size, nodal stage and metastasis status. ATP7B protein was detected in 30.9% (17/55 cases) of distal gastric carcinomas, markedly lower than that in gastric cardiac carcinomas (P = 0.037). CONCLUSION: ATP7B protein is frequently overexpressed in gastric cardiac carcinomas, and correlated with the differentiation of cardiac carcinoma. ATP7B expression in gastric cardiac carcinomas is significantly higher than that in distal gastric carcinomas, which might partially explain the difference of chemotherapy response and prognosis between these two gastric carcinomas.
Subject(s)
Adenocarcinoma/metabolism , Adenosine Triphosphatases/metabolism , Cation Transport Proteins/metabolism , Esophageal Sphincter, Lower/metabolism , Gastric Mucosa/metabolism , Stomach Neoplasms/metabolism , Adenocarcinoma/pathology , Adult , Aged , Copper-Transporting ATPases , Esophageal Sphincter, Lower/pathology , Female , Humans , Immunohistochemistry , Male , Middle Aged , Stomach/pathology , Stomach Neoplasms/pathologyABSTRACT
Genetic abnormalities of proto-oncogenes and tumor suppressor genes have been demonstrated to be changes that are frequently involved in esophageal cancer pathogenesis. However, hypermethylation of CpG islands, an epigenetic event, is coming more and more into focus in carcinogenesis of the esophagus. Recent studies have proved that promoter hypermethylation of tumor suppressor genes is frequently observed in esophageal carcinomas and seems to play an important role in the pathogenesis of this tumor type. In this review, we will discuss current research on genes that are hypermethylated in human esophageal cancer and precancerous lesions of the esophagus. We will also discuss the potential use of hypermethylated genes as targets for detection, prognosis and treatment of esophageal cancer.
