Correlation between chemosensitivity to anticancer drugs and telomerase reverse transcriptase mRNA expression in gastric cancer.

BACKGROUND: The determination of sensitive chemotherapy drugs for gastric cancer (GC) is one of the greatest challenges of adjuvant therapy. Here we evaluated the chemosensitivity of GC to anticancer drugs and the telomerase reverse transcriptase (hTERT) mRNA expression, and investigated the relationship of them. METHODS: The GC cells which were collected from 68 patients with primary GC were primary cultured. The chemosensitivity of GC cells to anticancer drugs was evaluated successfully using the MTT assay for 60 cases of GC cells, and the hTERT mRNA expression was examined in 60 cases of GC tissues and corresponding normal gastric mucosa and 6 cases of chronic superficial gastritis mucosa by in situ hybridization. RESULTS: Taxol, cisplatin and 5-fluorouracil were in general more effective than adriamycin and mitomycin for GC cells, and the chemosensitivity to anticancer drugs was associated with tumor histological types and a worse tumor grade. Compared to normal gastric mucosa tissues, hTERT mRNA expression was significantly increased in GC (P<0.05), which was related with a worse differentiation and drug-resistance to 5-fluorouracil or adriamycin in GC. CONCLUSIONS: These data demonstrate for the first time that examinations of hTERT mRNA expression as an important factor could be used to select the chemotherapeutic drugs for GC patients. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1793217009875483.

Expression of pyruvate dehydrogenase kinase-1 in gastric cancer as a potential therapeutic target.

In contrast to mitochondria in healthy cells, which utilize oxidative phosphorylation, malignant cells undergo elevated glycolysis for energy production using glucose. The objectives of this study were to evaluate whether the expression of various molecules, including pyruvate dehydrogenase kinase-1 (PDK-1), is involved in the altered glucose metabolism associated with gastric cancer prognosis and to assess the role of a therapeutic agent in targeting glucose metabolism in gastric cancer. Immunohistochemistry was performed on gastric cancer tissues obtained from 152 patients who underwent curative resection to assess the expression of hypoxia-inducible factor-1α (HIF-1α), glucose transporter-1 (GLUT-1), hexokinase-2 (HK-2) and PDK-1. In an in vitro analysis, the lactate production and glucose uptake levels, cellular viability and 5-fluorouracil (5-FU) responses were evaluated before and after treatment with dichloroacetate (DCA), a PDK-1 inhibitor, in the MKN45 and AGS gastric cancer cell lines and in the non-cancerous HEK293 cell line. GLUT-1 and PDK-1 expression was significantly associated with tumor progression, although only PDK-1 expression was an independent prognostic factor for patients who received 5-FU adjuvant treatment. There was no significant difference in cell viability between the HEK293 and gastric cancer cell lines following DCA treatment. However, DCA treatment reduced lactate production and increased responsiveness to 5-FU in MKN45 cells, which expressed high levels of PDK-1 in comparison to the other cell lines. Thus, PDK-1 may serve as a biomarker of poor prognosis in patients with gastric cancer. In addition, PDK-1 inhibitors such as DCA may be considered an additional treatment option for patients with PDK-1-expressing gastric cancers.

Expression of orotate phosphoribosyl transferase in human pancreatic cancer: implication for the efficacy of uracil and tegafur-based adjuvant chemotherapy.

The enzyme orotate phosphoribosyl transferase (OPRT) is involved in the metabolism of the anticancer drug 5-fluorouracil (5-FU), and is a key enzyme for conversion of 5-FU to its active form in tumor tissue. Little is known regarding the significance of OPRT in human pancreatic cancer. The present study was designed to assess the association between the activity of OPRT in the tumor, and the clinicopathological status and prognosis of human resectable pancreatic cancer, especially regarding its relevance to the efficacy of adjuvant chemotherapy with uracil and tegafur (UFT), cyclophosphamide (CPA) and/or gemcitabine (GEM). The present study included 99 resectable pancreatic cancers, which were all invasive ductal tubular carcinomas. OPRT was immunostained with a rabbit anti-human OPRT polyclonal antibody. OPRT was positively stained in 54 (54.5%) of 99 pancreatic cancers. The post-surgical survival rate of the OPRT (+) pancreatic cancers was significantly higher than that of the OPRT (-) ones. In the OPRT (+) group, the survival rate of the patients, who received adjuvant chemotherapy (ACT) with UFT, CPA or GEM, was significantly higher than that of the patients without ACT; however, in the OPRT (-) group, there was no difference in the survival between the ACT (+) and (-) groups. Multivariate analyses demonstrated that for all patients, primary tumor, status of nodal involvement (pN), residual tumor, level of dissection and CPA were significant variables for the prognosis: in OPRT (+) groups, primary tumor, nodal involvement, GEM and CPA were significant variables. In contrast, in the OPRT (-) group, pN was the only significant variable. The present study is the first report on the significance of OPRT in human pancreatic cancer, and the results indicate that the expression of OPRT may be useful to predict the response to adjuvant chemotherapy in human pancreatic cancer.

The natural protein kinase C alpha mutant is present in human thyroid neoplasms.

An altered protein expression of Ca(2+)-dependent protein kinase C (PKC) isoforms and a point mutation in the PKC alpha cDNA (position 908 of the nucleotide sequence, position 294 of the amino acid sequence, substitution of an aspartic acid by a glycine) have been previously described in a subpopulation of human pituitary tumors. In this work, we screened 16 thyroid tissue samples (four follicular adenomas, five colloid adenomas, three papillary carcinomas, one follicular carcinoma and three normal tissues adjacent to the tumors) for the presence of the PKC alpha point mutation and for PKC alpha, beta 1, beta 2, epsilon and delta protein expression. Screening for the presence of the PKC alpha mutant was performed by a subcloning technic. The polymerase chain reaction products were generated using reverse-transcribed cDNAs, subcloned and sequenced (10 clones were routinely sequenced). The PKC alpha point mutation at position 908 of the cDNA sequence was found in four out of the nine adenomas and in the follicular carcinoma. It was neither detected in the papillary carcinomas nor in the adjacent normal tissues (one was the adjacent normal tissue of the follicular carcinoma; in this sample, genomic DNA and cDNA were used to look for the presence of the mutant), demonstrating the somatic nature of this mutant. Western blot analysis of PKC isoforms showed that the expression of all isoforms was higher in the thyroid neoplasms as compared with their adjacent normal tissue (n = 3). It was also higher in the samples containing the PKC mutant (two follicular adenomas, two colloid adenomas and the follicular carcinoma) as compared with the tumors where it was not detected (three papillary carcinomas and five adenomas). Samples could be ordered according to their increasing PKC expression as follows: normal adjacent tissue < follicular adenomas without PKC alpha mutant < or = papillary carcinoma < follicular adenomas with PKC mutant < follicular carcinoma with PKC mutant. In conclusion, the discovery of the PKC alpha mutant in thyroid neoplasms demonstrates that this mutant is not particular to human pituitary tumors where it was originally detected. It is a somatic mutation and its presence is concomitant with high levels of all of the PKC isoforms analysed. The presence of the PKC mutant in thyroid neoplasms raises the question of its importance in thyroid tumorigenesis.