Shuji Kotoh

APPLICATION OF MICROWAVE TISSUE COAGULATOR IN PARTIAL NEPHRECTOMY FOR RENAL CELL CARCINOMA

PURPOSE At partial nephrectomy there is a risk of excessive blood loss, which necessitates transfusion and also results in renal function deterioration when a vascular clamp is used. We evaluated the usefulness of a microwave tissue coagulator for partial nephrectomy for renal cell carcinoma. MATERIALS AND METHODS Partial nephrectomy was performed without renal pedicle clamping using a microwave tissue coagulator in 4 patients with a small kidney tumor. RESULTS In 3 of the 4 patients partial nephrectomy was successful using a microwave tissue coagulator without renal pedicle clamping. Mean operative time and blood loss were 203 minutes and 153 ml., respectively, and there were no significant complications. In the remaining case partial kidney resection was also performed without any complications. However, nephrectomy was required due to possible incomplete tumor resection. CONCLUSIONS Partial nephrectomy using a microwave tissue coagulator can be safe and successful without renal pedicle clamping. However, the insertion line of the microwave electrode must be carefully determined for resection to be curative and safe, just as when making the cut line for conventional partial nephrectomy or tumor enucleation.

Establishment and Characterization of Doxorubicin-Resistant Human Bladder Cancer Cell Line, Kk47/adm

A human bladder cancer cell line resistant to doxorubicin, KK47/ADM has been established in vitro by exposing KK47 parent cells to progressively higher concentrations of the drug over a period of 16 months. The KK47/ADM was 271 times more resistant to doxorubicin than the KK47 parent. The KK47/ADM exhibited cross-resistance to doxorubicin derivatives (pirarubicin, epirubicin), vinca alkaloids (vinblastine, vincristine) and etoposide, but not to cisplatin, carboplatin, mitomycin C, peplomycin and methotrexate. Unlike the KK47 parent, about 70% of the KK47/ADM cells showed a positive reaction with monoclonal antibody against P-glycoprotein, MRK16. Uptake and efflux studies with [14C]doxorubicin indicated that the resistance exhibited by the KK47/ADM line was mainly due to a lower accumulation of the drug caused by an increased active efflux, and these were reversed in the presence of verapamil. Although verapamil enhanced doxorubicin sensitivity of KK47/ADM, a complete overcoming of the resistance could not be obtained. These two lines with different chemosensitivity are thus considered to be a useful model for developing new chemotherapeutic strategies against multidrug resistant bladder cancer.

Recurrence of bladder tumors following surgery for transitional cell carcinoma of the upper urinary tract.

A retrospective analysis of 53 patients with an upper urinary tract (UUT) transitional cell carcinoma, which was treated surgically, was performed in relation to the development of a subsequent bladder tumor. In 19 of the 53 patients (35.8%) bladder tumors developed following surgery of a UUT tumor. The simultaneous occurrence of a bladder tumor and more than two tumors in the UUT had a significant influence on the rate of bladder tumor recurrence. On the other hand, location, mode of growth, grade, stage and vascular invasion of the UUT tumor, and history of bladder tumors did not seem to be related to the frequency of subsequent bladder tumors. These findings suggest that the diversity of UUT tumors at the time of diagnosis is an important factor in bladder tumor recurrence. Therefore, clinical and pathological examinations should be carefully performed in patients with UUT tumors.

Metallothionein expression is correlated with cisplatin resistance in transitional cell carcinoma of the urinary tract.

Metallothioneins (MTs) are small cysteine-rich, metal-binding proteins involved in resistance to heavy-metal toxicity, and are known to bind cisplatin. Several experiments suggest possible involvement of MT in cellular resistance to cisplatin. To investigate the relationship between MT expression and cisplatin resistance in urinary tract transitional cell carcinoma (TCC), immunohistochemical staining for MT was performed in 31 untreated TCCs of the urinary tract. The results were compared with the sensitivity of the tumors to cisplatin as assessed by the microtiter succinate dehydrogenase inhibition (mSDI) test. Variable MT expression was observed in all 31 TCCs, but there was no specific correlation between histopathological parameters and MT expression. Fourteen (87.5%) of the 16 TCCs with less than 10% of their tumor cells positive for MT were sensitive to cisplatin. On the other hand, 6 (75.0%) of the 8 TCCs with MT expression by more than 30% of their tumor cells were resistant to cisplatin, and there was a significant correlation between MT expression and cisplatin resistance (p < 0.01). These results suggest the possible involvement of MT in the intrinsic cisplatin resistance of urinary tract TCC and that immunohistochemical investigation of MT may be useful for predicting the response of these tumors to cisplatin therapy.

Enhanced Expression of gamma/Glutamylcysteine Synthetase and Glutathione S-transferase Genes in Cisplatin-Resistant Bladder Cancer Cells with Multidrug Resistance Phenotype

PURPOSE To elucidate the mechanisms of cisplatin resistance in human bladder cancer. MATERIALS AND METHODS After continuous exposure of KK47 cells to cisplatin, two resistant sublines, KK47/DDP10 and KK47/DDP20 were established. The glutathione content, glutathione S-transferase activity, and intracellular platinum concentration were measured while the expression of various drug resistance-related genes was examined. RESULTS KK47/DDP10 and KK47/DDP20 were respectively 9.3- and 18.7-fold more resistant to cisplatin than KK47, and also showed multidrug resistance. Decreased intracellular drug accumulation, increased glutathione content, elevated glutathione S-transferase activity, and an overexpression of gamma-glutamylcysteine synthetase and glutathione S-transferase pi genes were observed in the resistant sublines. CONCLUSIONS Multiple mechanisms, including decreased drug accumulation, increased intracellular glutathione and glutathione S-transferase pi, may contribute to the acquisition of cisplatin resistance in human bladder cancer.

Molecular analysis of mechanisms regulating drug sensitivity and the development of new chemotherapy strategies for genitourinary carcinomas.

A bstractThe emergence of drug-resistant tumors during treatment remains one of the major obstacles in cancer chemotherapy. Overexpression of P-glycoprotein encoded by the multidrug resistance 1 (MDR1) gene or multidrug resistance-associated protein (MRP) (or both) and decreased expression of DNA topoisomerase II are responsible for expression of the multidrug resistance (MDR) phenotype. The expression of P-glycoprotein is also often observed in untreated cancers showing spontaneous MDR, such as renal cell carcinoma. Regarding cisplatin resistance, decreased cisplatin accumulation, an increase in cisplatin detoxification by glutathione-related enzymes or metallothionein (or both), and increased repair of DNA damage are all considered to play an important role. The combination of reversal agents targeting such drug resistance markers may be a way to improve the outcome of chemotherapy. Regarding the presently available reversal agents, however, clinically relevant chemosensitizing doses cannot be given to humans without inducing significant toxicity. The development of new agents that reverse drug resistance without causing significant toxicity and their clinical application based on the mechanisms regulating drug sensitivity may therefore be a potentially effective new treatment strategy for genitourinary carcinomas.

Expression of P-glycoprotein and multidrug resistance in renal cell carcinoma

The expression of the multidrug-resistance gene product, P-glycoprotein was examined immunohistochemically in 31 untreated human renal cell carcinomas. In 17 of these, chemosensitivity to Adriamycin and vinblastine was also assessed by a microtiter succinate dehydrogenase inhibition test and the correlation between the expression of P-glycoprotein and intrinsic multidrug resistance was investigated. P-glycoprotein was detected in 16 (51.6%) of the 31 carcinomas. In the chemosensitivity test, 14 (82.4%) of the 17 carcinomas were estimated to be resistant to both drugs (multidrug resistant; MDR). Eight (72.7%) of the 11 carcinomas with a positive expression of P-glycoprotein were MDR, and none of them were sensitive of both drugs. On the other hand, MDR carcinomas were not necessarily associated with the expression of P-glycoprotein. Eight (61.5%) of the 13 MDR carcinomas showed a positive expression of P-glycoprotein while the remaining 5 (38.5%) were negative. These results suggest that the expression of P-glycoprotein is an important factor responsible for the intrinsic MDR phenotype of renal cell carcinoma, however, there are probably other factors involved as well which have yet to be fully elucidated.

Correlation between the expression of P-glycoprotein and multidrug-resistant phenotype in transitional cell carcinoma of the urinary tract

The expression of a multidrug-resistant (MDR) gene product, P-glycoprotein, was examined immunohistochemically in 41 transitional cell carcinomas (TCCs) of the urinary tract. In 23 of these, chemosensitivity to adriamycin (ADM) and vinblastine (VBL) was also assessed by a microtiter succinate dehydrogenase inhibition test and the correlation between the expression of P-glycoprotein and MDR phenotype was investigated. P-glycoprotein was detected in 13 (72.2%) of the 18 untreated TCCs of the upper urinary tract (UUT), 6 (31.6%) of the 19 untreated TCCs of the bladder, and all of the 4 TCCs treated with M-VAC chemotherapy, respectively. Fourteen (87.5%) of the 16 TCCs with a positive expression of P-glycoprotein were resistant to ADM and VBL, whereas all of the 4 TCCs sensitive to both drugs were negative in the expression of P-glycoprotein. The succinate dehydrogenase activity of TCCs with a positive expression of P-glycoprotein was significantly higher than that of TCCs with a negative expression of P-glycoprotein (P < 0.05). Thus, there was a good correlation between the expression of P-glycoprotein and MDR phenotype in the chemosensitivity test. These results suggest that intrinsic MDR exists in some TCCs of the urinary tract, particularly UUT, and that the immunohistochemical investigation of P-glycoprotein may be useful for predicting the MDR phenotype in TCCs of the urinary tract.

Non-P-glycoprotein-mediated atypical multidrug resistance in a human bladder cancer cell line

A human bladder cancer cell line resistant to adriamycin (ADM), T24/ADM9 has been established in vitro by exposing T24 parent cells to progressively higher concentrations of the drug over a period of 12 months. The T24/ADM9 cells were found to be 9 times more resistant to ADM than the T24 parent, and showed various degrees of cross‐resistance to an ADM derivative, vinca alkaloids and a DNA topoisomerase II (Topo ID‐targeting agent, etoposide. No significant difference was observed in the cellular accumulation of ADM between the T24/ADM9 and T24 parent cells. A Northern blot analysis showed an overexpression of multidrug resistance‐associated protein (MRP) mRNA, but no overexpression of multidrug resistance‐1 (MDR1) mRNA was observed in the T24/ADM9 cells. A flow cytometric analysis showed that the MDR1 gene product, P‐glycoprotein (Pgp), is not expressed on the T24/ADM9 cells. T24/ADM9 showed approximately the parental level of DNA Topo II catalytic activity. In Western blot and Northern blot analyses, however, the cellular level of DNA topo II was apparently much lower in T24/ADM9 than in the T24 parent. Thus, these results suggest that a decreased cellular level of DNA Topo II and an overexpression of MRP gene may be responsible for the expression of an MDR phenotype in the T24/ADM9 cells and that such non‐Pgp‐mediated, atypical MDR may develop in bladder cancer treated with chemotherapy including ADM.

Treatment of advanced hormone-refractory prostate carcinoma with a combination of etoposide, pirarubicin and cisplatin

A total of 20 patients with hormone-refractory prostate carcinoma entered a pilot study of combination chemotherapy based on the EAP (etoposide, Adriamycin and cisplatin) regimen, in which Adriamycin was replaced by pirarubicin, a less cardiotoxic derivative of Adriamycin. The response was assessed by criteria modified from those of the National Prostatic Cancer Project: prostate-specific antigen was employed instead of acid phosphatase. Of 18 evaluable patients, 6 achieved a partial response, 5 had stable disease, and in 7 the disease had progressed during therapy; thus, the overall response rate was 33.3% [95% confidence interval (CI) 11.5–55.1%]. Significant pain alleviation and performance status improvement were obtained in 5 of 12 patients (41.7%; CI 13.8–69.6%) and 3 of 13 patients (23.1%; CI 0.2–46.0%), respectively. Although myelosuppression was moderate to severe, no chemotherapy-related deaths or bacteriologically documented sepsis occurred; nor was there any clinical cardiotoxicity. All the responding patients received maintenance chemotherapy with etoposide thereafter. At present, the median duration of response is 33 weeks (range: 23–91 weeks) and the median survival period for all patients is 42 weeks (range: 27+ −136 weeks), with 12 deaths. In spite of the small number of patients treated, these results suggest that this chemotherapy regimen is active in advanced hormone-refractory prostate carcinoma.