A change in microsatellite instability caused by cisplatin-based chemotherapy of ovarian cancer

To clarify the mechanism of acquired CDDP resistance in ovarian cancer, we compared the microsatellite instability (MSI) by the amplification of 10 microsatellite loci and immunohistochemical detection of hMSH2 and hMLH1 expression between the primary resected tumours and the secondary resected residual tumours after 5 or 6 courses of CDDP-based chemotherapy in the 24 cases of ovarian cancer. Of the 24 primary resected tumours, 9 (37.5%) showed MSI (7 cases of MSI-L, 2 cases of MSI-H), while 15 (72.5%) were microsatellite stable tumours (MSS). The primary tumours also had MSI in the residual tumours after CDDP-based chemotherapy. However, all of the cases with MSS in the primary resected tumours exhibited MSI (2 cases were MSI-L, and 13 cases were MSI-H) in the residual tumours after CDDP-based chemotherapy (P< 0.001). Furthermore, 11 (73.3%) of these cases which changed from MSS to MSI also had a change in the expression of hMLH1 from positive to undetectable (P< 0.001). Our data suggest that tumour MSI changes during CDDP-based chemotherapy, and that the loss of hMLH1 expression is one of the factors that has the greatest effect on this transformation. © 2001 Cancer Research Campaignhttp://www.bjcancer.co

Potential predictive markers of chemotherapy resistance in stage III ovarian serous carcinomas

<p>Abstract</p> <p>Background</p> <p>Chemotherapy resistance remains a major obstacle in the treatment of women with ovarian cancer. Establishing predictive markers of chemoresponse would help to individualize therapy and improve survival of ovarian cancer patients. Chemotherapy resistance in ovarian cancer has been studied thoroughly and several non-overlapping single genes, gene profiles and copy number alterations have been suggested as potential markers. The objective of this study was to explore genetic alterations behind chemotherapy resistance in ovarian cancer with the ultimate aim to find potential predictive markers.</p> <p>Methods</p> <p>To create the best opportunities for identifying genetic alterations of importance for resistance, we selected a homogenous tumor material concerning histology, stage and chemotherapy. Using high-resolution whole genome array comparative genomic hybridization (CGH), we analyzed the tumor genomes of 40 fresh-frozen stage III ovarian serous carcinomas, all uniformly treated with combination therapy paclitaxel/carboplatin. Fisher's exact test was used to identify significant differences. Subsequently, we examined four genes in the significant regions (<it>EVI1</it>, <it>MDS1</it>, <it>SH3GL2</it>, <it>SH3KBP1</it>) plus the <it>ABCB1 </it>gene with quantitative real-time polymerase chain reaction (QPCR) to evaluate the impact of DNA alterations on the transcriptional level.</p> <p>Results</p> <p>We identified gain in 3q26.2, and losses in 6q11.2-12, 9p22.3, 9p22.2-22.1, 9p22.1-21.3, Xp22.2-22.12, Xp22.11-11.3, and Xp11.23-11.1 to be significantly associated with chemotherapy resistance. In the gene expression analysis, <it>EVI1 </it>expression differed between samples with gain versus without gain, exhibiting higher expression in the gain group.</p> <p>Conclusion</p> <p>In conclusion, we detected specific genetic alterations associated with resistance, of which some might be potential predictive markers of chemotherapy resistance in advanced ovarian serous carcinomas. Thus, further studies are required to validate these findings in an independent ovarian tumor series.</p

DNA topoisomerase I and II expression in drug resistantgerm cell tumours

A small number of testicular germ cell tumours are refractory to current chemotherapy regimens. DNA topoisomerase I is the target for several new drugs and a potential candidate treatment for chemorefractory germ cell tumours. DNA topoisomerase IIα is the target for etoposide, which is currently used regularly in germ cell tumour treatment. The expression of DNA topoisomerase I and IIα were therefore assessed immunohistochemically in a range of testicular tumours, especially those with persistent malignant elements on retroperitoneal lymph node dissection. Pre-chemotherapy orchidectomy specimens were matched with post-chemotherapy retroperitoneal lymph node dissections to examine changes in expression. There was considerable variation in the expression of topoisomerase I in different tumour types. Both yolk sac tumours and teratoma, mature showed universal expression of topoisomerase I, while 38% of seminomas and 30% of embryonal carcinomas were positive. Strong topoisomerase IIα expression was found in embryonal carcinoma. There was a negative correlation between topoisomerase I and IIα expression (P=0.004) and downregulation of topoisomerase IIα after chemotherapy (P=0.02). Topoisomerase I expression appears to increase in those cases with residual teratoma, mature, but is largely unchanged in those cases remaining as embryonal carcinoma. These results suggest that topoisomerase I inhibitors may be useful in chemorefractory germ cell tumours, especially yolk sac tumours and where there are unresectable residual teratoma, mature deposits

Valproate, carnitine metabolism, and biochemical indicators of liver function.

The effects of valproate (VPA) on carnitine and lipid metabolism and on liver function were assessed in 213 age- and sex-matched outpatients from five centers, with the following distribution: VPA monotherapy, 54; VPA polytherapy, 55; other monotherapies, 51; and untreated, 53. Mean total and free carnitine levels were significantly lower in patients with polytherapy; acylcarnitine was significantly higher for VPA monotherapy and the ratio of acyl- to free carnitine was significantly higher in all patients receiving VPA. Ammonia, uric acid, and bilirubin were the only tests selectively impaired with VPA. A significant correlation was found between serum ammonia and VPA dosage. Glucose, beta-lipoproteins, triglycerides, acetacetate, and beta-hydroxybutyrate were unchanged in the four groups. Sex and age appeared to interact with total and free carnitine values. Adverse drug reactions were apparently unrelated to carnitine metabolism impairment. Only a few patients had abnormal carnitine values. Our data support the assumption that carnitine deficiency and abnormal liver function due to VPA are mostly subclinical events