Using the geriatric nutritional risk index to predict outcomes in older patients with remnant gastric cancer after gastrectomy: a retrospective multicenter study in Japan.

PURPOSE: This study investigated the prognostic value of the geriatric nutritional risk index (GNRI) in patients undergoing curative gastrectomy for remnant gastric cancer (RGC). METHODS: This multicenter retrospective study included 105 patients with RGC of ≥ 65 years of age who underwent curative gastrectomy at 10 institutions in Japan between January 2000 and December 2016. Postoperative complications, overall survival (OS), and disease-specific survival (DSS) were analyzed. RESULTS: Receiver operating curve analyses indicated that the optimal cutoff value of the GNRI for OS was 95.4. Patients were categorized into high and low GNRI groups based on the optimal GNRI cutoff value. The GNRI was significantly correlated with body mass index (p < 0.001), amount of bleeding (p = 0.021), Clavien-Dindo grade 5 postoperative complications (p = 0.040), death caused by primary disease (p = 0.010), and death caused by other diseases (p = 0.002). The OS and DSS were significantly worse in the low GNRI group. A low GNRI and T3 or deeper tumor invasion were independent prognostic factors for OS and DSS. CONCLUSIONS: The GNRI is a promising predictor of both short- and long-term outcomes in older patients with RGC.

Estimation of the physiologic ability and surgical stress scoring system as a useful predictor of postoperative recurrence in patients with stage II colorectal cancer: a multicenter study.

PURPOSE: We determined the usefulness of the estimation of physiologic ability and surgical stress (E-PASS), initially reported as a predictive factor for postoperative morbidity and mortality, as a prognostic indicator in stage II colorectal cancer (CRC). METHODS: Overall, 739 patients who underwent proctocolectomy for CRC at Tottori University Hospital and affiliated hospitals and histologically diagnosed with stage II CRC were included in the current study. RESULTS: A receiver operating characteristic (ROC) analysis of the five-year recurrence-free survival indicated that the comprehensive risk score (CRS) of E-PASS predicted postoperative recurrence. A multivariate analysis revealed that the presence of preoperative perforation, T4, v ≥ 2, and CRSHigh (≥ 0.2267) were independent predictors of postoperative recurrence. Patients were assigned a score using these factors, as follows: the presence of perforation = 1, the absence of preoperative perforation = 0, T4 = 1, T3 = 0, v2/3 = 1, v0/1 = 0, CRSHigh = 1, and CRSLow = 0 (total score: 0-4). Accordingly, the respective 5-year relapse-free survival rates were 91.0%, 83.6%, 70.3%, and 52.0% among those with scores of 0, 1, 2, and both 3 and 4 (P < 0.001). CONCLUSIONS: The CRS predicts postoperative recurrence in patients with stage II CRC.

Impact of geriatric nutritional risk index on outcomes after gastrectomy in elderly patients with gastric cancer: a retrospective multicenter study in Japan.

BACKGROUND: Several studies investigated the utility of inflammation and nutritional markers in predicting the prognosis in patients with gastric cancer; however, the markers with the best predictive ability remain unclear. This retrospective study aimed to determine inflammation and nutritional markers that predicted prognosis in elderly patients over 75 years of age undergoing curative gastrectomy for gastric cancer. METHODS: Between January 2005 and December 2015, 497 consecutive elderly gastric cancer patients aged over 75 years underwent curative gastrectomy in 12 institutions. The geriatric nutritional risk index (GNRI), prognostic nutritional index, neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, and C-reactive protein/albumin ratio were examined as prognostic markers for overall survival (OS) and disease-specific survival (DSS) using area under the curve (AUC) using receiver operating characteristic (ROC) curve analysis. RESULTS: The GNRI had the highest AUC and predictive value for both OS (0.637, p < 0.001) and DSS (AUC 0.645, p < 0.001). The study cohort was categorized into the high and low GNRI groups based on the optimal GNRI cut-off values for OS (97.0) and DSS (95.8) determined with the ROC analysis. For both OS and DSS, there was a significant correlation between the GNRI and several clinicopathological factors including age, body mass index, albumin, American Society of Anesthesiologists physical status score, depth of tumor invasion, lymph node metastasis, lymphatic invasion, pathological stage, operation duration, bleeding, procedure, approach, death due to primary disease, and death due to other disease. The GNRI remained a crucial independent prognostic factor for both OS (Hazard ratio [HR] = 1.905, p < 0.001) and DSS in multivariate analysis (HR = 1.780, p = 0.043). CONCLUSIONS: Among a panel of inflammation and nutritional markers, the GNRI exhibited the best performance as a prognostic factor after curative gastrectomy in elderly patients with gastric cancer, indicating its utility as a simple and promising index for predicting OS and DSS in these patients.

Risk factors for recurrence in elderly patients with stage II colorectal cancer: a multicenter retrospective study.

BACKGROUND: Adjuvant chemotherapy for stage II colorectal cancer (CRC) is considered appropriate for patients with risk factors for recurrence, rather than for all patients uniformly. However, the risk factors for recurrence remain controversial, and there is limited information, especially for elderly patients. The Geriatric Nutritional Risk Index (GNRI) is widely used as a simple nutritional screening tool in the elderly and is associated with cancer prognosis and recurrence. This study aimed to investigate the risk factors for recurrence in the elderly with stage II CRC, focusing on the GNRI. METHODS: We enrolled 348 elderly patients (≥ 75 years) with stage II CRC who underwent curative resection at the Department of Surgery, Tottori University and our 10 affiliated institutions. The patients were divided into GNRIhigh (≥ 93.465) and GNRIlow (< 93.465) groups. RESULTS: The GNRIlow group showed a significantly worse overall survival (OS), cancer-specific survival (CSS), and relapse-free survival (RFS) (P < 0.001, P < 0.001, and P < 0.001, respectively). In a multivariate analysis, GNRIlow (hazard ratio [HR]: 2.244, P < 0.001), pathologic T4 stage (HR: 1.658, P = 0.014), and moderate to severe lymphatic or venous invasion (HR: 1.460, P = 0.033) were independent factors affecting RFS. By using these three factors to score the risk of recurrence from 0 to 3 points, the prognosis was significantly stratified in terms of OS, CSS, and RFS (P < 0.001, P < 0.001, and P < 0.001, respectively). The recurrence rate for each score was as follows: 0 points, 9.8%; 1 point, 22.0%; 2 points, 37.3%; and 3 points, 61.9%. CONCLUSIONS: GNRIlow, pathologic T4 stage, and moderate to severe lymphatic or venous invasion are high-risk factors for recurrence in the elderly with stage II CRC. The scoring system using these three factors appropriately predicted their recurrence and outcome.

Topoisomerase I expression in tumors as a biological marker for CPT-11 chemosensitivity in patients with colorectal cancer.

Irinotecan (CPT-11) is used as a first- and second-line chemotherapy for advanced or recurrent colorectal cancer (CRC). However, only 20%-30% of patients show an objective response to CPT-11 and the drug has severe toxicities, such as delayed-onset diarrhea, neutropenia, nausea, and vomiting. It is important to select patients who will demonstrate sensitivity to CPT-11 treatment to avoid unnecessary drug toxicities and to introduce anticancer treatment benefits to CRC patients. DNA topoisomerase I (Topo I) is essential for vital cellular processes such as DNA replication, transcription, translation, recombination, and repair. This article reviews the possibility of assessing Topo I protein expression in tumors as a biological marker for CPT-11 treatment in CRC.

Fucoidan reduces the toxicities of chemotherapy for patients with unresectable advanced or recurrent colorectal cancer.

Combination chemotherapy with oxaliplatin plus 5-fluorouracil/leucovorin (FOLFOX) or irinotecan plus 5-fluorouracil/leucovorin (FOLFIRI) has become a standard regimen for advanced or recurrent colorectal cancer. Numerous studies have reported that long-term use of FOLFOX or FOLFIRI leads to better survival for these patients. Thus, control of the toxicity of these drugs may be crucial to prolonging survival. Fucoidan is one of the major sulfated polysaccharides of brown seaweeds and exhibits a wide range of biological activities. In the present study, we analyzed the effect of fucoidan on suppressing the toxicity of anti-cancer drugs. A total of 20 patients with unresectable advanced or recurrent colorectal cancer scheduled to undergo treatment with FOLFOX or FOLFIRI were randomly allocated into a fucoidan treatment group (n=10) and a control group without fucoidan treatment (n=10). Results showed that fucoidan regulated the occurrence of fatigue during chemotherapy. Chemotherapy with fucoidan was continued for a longer period than chemotherapy without fucoidan. Additionally, the survival of patients with fucoidan treatment was longer than that of patients without fucoidan, although the difference was not significant. Thus, fucoidan may enable the continuous administration of chemotherapeutic drugs for patients with unresectable advanced or recurrent colorectal cancer, and as a result, the prognosis of such patients is prolonged.

Multicenter safety study of mFOLFOX6 for unresectable advanced/recurrent colorectal cancer in elderly patients.

BACKGROUND: Combination chemotherapy with oxaliplatin plus 5-fluorouracil/leucovorin (FOLFOX) has become a standard regimen for colorectal cancer. An increase of adverse events with combination chemotherapy is predicted in elderly patients, and it remains controversial whether they should receive the same chemotherapy as younger patients. Accordingly, this study of modified FOLFOX6 (mFOLFOX6) therapy was performed to compare its safety between elderly and non-elderly patients. METHODS: We prospectively studies 14 non-elderly patients aged <70 years old and 8 elderly patients aged >or= 70 years with unresectable advanced/recurrent colorectal cancer who received mFOLFOX6 therapy during the period from March 2006 to March 2007. Adverse events and the response to treatment were compared between the elderly and non-elderly groups. RESULTS: The main adverse events were neutropenia and peripheral neuropathy, which occurred in 62.5% (>or= grade 3) and 87.5% (>or= grade 1) of elderly patients. The grade and frequency of adverse events were similar in the elderly and non-elderly groups. In some patients with neutropenia, treatment could be continued without reducing the dose of oxaliplatin by deleting bolus 5-fluorouracil. A correlation was found between the cumulative dose of oxaliplatin and the severity of neuropathy, and there were 2 elderly and 3 younger patients in whom discontinuation of treatment was necessary due to peripheral neuropathy. The median number of treatment cycles was 10.0 and 9.5 in the non-elderly and elderly groups, respectively. The response rate was 60.0% in the non-elderly and 50.0% in the elderly group, while the disease control rate was 100% and 83.3% respectively, showing no age-related difference. CONCLUSION: mFOLFOX6 therapy was well-tolerated and effective in both non-elderly and elderly patients. However, discontinuation of treatment was sometimes necessary due to peripheral neuropathy, which is dose-limiting toxicity of this therapy.

Expression of phosphorylated Akt (pAkt) in gastric carcinoma predicts prognosis and efficacy of chemotherapy.

BACKGROUND: The Akt signaling pathway controls the survival and growth of human cancers. We investigated the expression of phosphorylated Akt (pAkt) in patients with gastric cancer. METHODS: The expression of pAkt was immunohistochemically examined in 140 gastric cancer patients who underwent a gastrectomy. The expression of pAkt was evaluated based on staining intensity, and staining was classified as negative or positive. We examined the expression of pAkt and its association with the clinicopathological findings, prognosis, depth of invasion, the expression of p53, and efficacy of oral fluorouracil chemotherapy after surgery. RESULTS: Expression of pAkt was positive in 81 (58%) patients and negative in 59 (42%) patients. There were no significant correlations between pAkt expression and the clinicopathological findings. The prognosis of patients with pAkt-negative tumors was superior to that of patients with pAkt-positive tumors, and the difference was significant for T3/T4 gastric cancer (P < 0.05). Among the patients with T3/T4 gastric cancer, postoperative oral fluorouracil treatment was effective in those who were pAkt-positive. Multivariate analysis revealed that pAkt expression and lymph node metastasis were independent prognostic factors. In 88 patients with T3 gastric carcinoma who had undergone curative surgery, in whom we studied the prognostic impact of a combined analysis of pAkt and p53 expression, patients with both pAkt- and p53-positive tumors showed a significantly poorer prognosis than patients with either or both pAkt- and p53-negative tumors (P < 0.05). CONCLUSION: Our results indicate that pAkt expression may be useful for predicting the prognosis and efficacy of fluorouracil treatment in patients with gastric cancer.

Tumor cyclooxygenase-2 gene suppresses local immune responses in patients with hepatocellular carcinoma.

AIMS AND BACKGROUND: In several neoplastic diseases including hepatocellular carcinoma (HCC) immunosuppression is correlated with disease stage, progression and outcome. Moreover, recent studies have demonstrated that cyclooxygenase-2 (COX-2) enhances tumor growth in HCCs. The present study analyzed the correlation between local immune responses and COX-2 gene expression levels in patients with primary HCCs. METHODS: Fresh tissues were obtained from 59 patients who underwent resection of an HCC. The COX-2 gene expression levels were quantified by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and compared with the CD8+ T cell densities detected by immunohistochemistry. RESULTS: COX-2 gene expression was detected in 35 of the 59 tumors. The CD8+ T cell density in COX-2-expressing tumors (6.1 cells/high-power field (HPF), x200 magnification) was suppressed compared with that in non-COX-2-expressing tumors (13.6 cells/HPF, P = 0.009). Tumor COX-2 gene expression was associated with a poorer disease-free survival rate. CONCLUSIONS: Elevation of the tumor COX-2 level is correlated with the suppression of local immune responses in HCCs, suggesting that COX-2 plays a role in early tumor recurrence in the residual liver in patients after HCC resection.

Intracellular localization and trafficking of fluorescein-labeled cisplatin in human ovarian carcinoma cells.

PURPOSE: We sought to identify the subcellular compartments in which cisplatin [cis-diamminedichloroplatinum (DDP)] accumulates in human ovarian carcinoma cells and define its export pathways. EXPERIMENTAL DESIGN: Deconvoluting digital microscopy was used to identify the subcellular location of fluorescein-labeled DDP (F-DDP) in 2008 ovarian carcinoma cells stained with organelle-specific markers. Drugs that block vesicle movement were used to map the traffic pattern. RESULTS: F-DDP accumulated in vesicles and were not detectable in the cytoplasm. F-DDP accumulated in the Golgi, in vesicles belonging to the secretory export pathway, and in lysosomes but not in early endosomes. F-DDP extensively colocalized with vesicles expressing the copper efflux protein, ATP7A, whose expression modulates the cellular pharmacology of DDP. Inhibition of vesicle trafficking with brefeldin A, wortmannin, or H89 increased the F-DDP content of vesicles associated with the pre-Golgi compartments and blocked the loading of F-DDP into vesicles of the secretory pathway. The importance of the secretory pathway was confirmed by showing that wortmannin and H89 increased whole cell accumulation of native DDP. CONCLUSIONS: F-DDP is extensively sequestered into vesicular structures of the lysosomal, Golgi, and secretory compartments. Much of the distribution to other compartments occurs via vesicle trafficking. F-DDP detection in the vesicles of the secretory pathway is consistent with a major role for this pathway in the efflux of F-DDP and DDP from the cell.

Cisplatin rapidly down-regulates its own influx transporter hCTR1 in cultured human ovarian carcinoma cells.

PURPOSE: Cisplatin (DDP)-resistant cells commonly exhibit reduced drug accumulation. Previous studies have shown that the major copper (Cu) influx transporter CTR1 controls the uptake of DDP in yeast and mammalian cells. The goal of this study was to examine the effect of Cu and DDP on the level and subcellular localization of hCTR1 protein in human ovarian carcinoma cells. EXPERIMENTAL DESIGN: Cultured human ovarian carcinoma A2780 cells were exposed to DDP and Cu, and the effect on hCTR1 was determined using Western blot analysis and confocal digital deconvolution microscopy. RESULTS: Loss of hCTR1 was triggered by DDP exposure in a concentration and time-dependent manner. Exposure to 0.5 micromol/L DDP for 5 minutes reduced hCTR1 levels and exposure to DDP concentrations > or =2 micromol/L caused almost complete disappearance. The loss of hCTR1 was observed within 1 minute of the start of exposure to 2 micromol/L DDP. Treatment of cells with 100 micromol/L Cu for 5 minutes produced a smaller effect. Pretreatment of cells with 2 micromol/L DDP for 5 minutes resulted in a 50% decrease in 64Cu uptake, demonstrating that the DDP-induced loss of hCTR1 detected by Western blot analysis and imaging was functionally significant. CONCLUSIONS: DDP down-regulated the amount of its major influx transporter in cultured human ovarian carcinoma cells in a concentration- and time-dependent manner. The effect was observed at DDP concentrations within the range found in the plasma of patients being treated with DDP, and it occurred very quickly relative to the half-life of the drug.

The role of copper transporters in the development of resistance to Pt drugs.

Recent studies in yeast, mouse and human cells suggest that the conserved metal binding transporters of the Cu homeostasis pathway can mediate resistance to Pt drugs in cancer cells. This review summarizes the data available from these studies. The observation that cells selected for resistance to Cu or the Pt drugs display bidirectional cross-resistance, parallel defects in the transport of Cu and the Pt drugs and altered expression of Cu transporters is consistent with the concept that the Cu homeostasis proteins regulate sensitivity to the Pt drugs by influencing their uptake, efflux and intracellular distribution. This model is supported by the finding that when mammalian and yeast cells are genetically engineered to express altered levels of the Cu transporters they exhibit altered sensitivity to Pt drugs and are defective in intracellular Pt accumulation due to altered uptake and/or efflux rates. Negative associations between the expression of ATP7A and ATP7B and the outcome of Pt therapy further support the significance of the Cu homeostasis proteins as both markers of and contributors to Pt resistance.

Increased expression of the copper efflux transporter ATP7A mediates resistance to cisplatin, carboplatin, and oxaliplatin in ovarian cancer cells.

PURPOSE: The goal of this study was to determine the effect of small changes in ATP7A expression on the pharmacodynamics of cisplatin, carboplatin, and oxaliplatin in human ovarian carcinoma cells. EXPERIMENTAL DESIGN: Drug sensitivity and cellular pharmacology parameters were determined in human 2008 ovarian carcinoma cells and a subline transfected with an ATP7A-expression vector ATP7A (2008/MNK). Drug sensitivity was determined by clonogenic assay, platinum (Pt) levels were measured by inductively coupled plasma mass spectroscopy, copper (Cu) accumulation was quantified with (64)Cu, and the subcellular distribution of ATP7A was assessed by confocal digital microscopy. RESULTS: The 1.5-fold higher expression of ATP7A in the 2008/MNK cells was sufficient to alter Cu cellular pharmacokinetics but not confer Cu resistance. In contrast, it was sufficient to render the 2008/MNK cells resistant to cisplatin, carboplatin, and oxaliplatin. Resistance was associated with increased rather than decreased whole-cell Pt drug accumulation and increased sequestration of Pt into the vesicular fraction. Cu triggered relocalization of ATP7A away from the perinuclear region, whereas at equitoxic concentrations the Pt drugs did not. CONCLUSIONS: A small increase in ATP7A expression produced resistance to all three of the clinically available Pt drugs. Whereas increased expression of ATP7A reduced Cu accumulation, it did not reduce accumulation of the Pt drugs. Under conditions where Cu triggered ATP7A relocalization, the Pt drugs did not. Thus, although ATP7A is an important determinant of sensitivity to the Pt drugs, there are substantial differences between Cu and the Pt drugs with respect to how they interact with ATP7A and the mechanism by which ATP7A protects the cell.

Confocal microscopic analysis of the interaction between cisplatin and the copper transporter ATP7B in human ovarian carcinoma cells.

Some cisplatin (DDP)-resistant cells overexpress the copper export transporter ATP7B, and cells molecularly engineered to overexpress ATP7B are resistant to DDP. The interaction of Cu with ATP7B normally triggers its relocalization from the perinuclear region to more peripheral vesicles. To investigate the interaction of DDP with ATP7B, we examined the effect of DDP on the subcellular localization of ATP7B using human ovarian carcinoma cells expressing a cyan fluorescent protein (ECFP)-tagged ATP7B (2008/ECFP-ATP7B). ATP7B expression was confirmed in 2008/ECFP-ATP7B cells by Western blotting, and its functionality was documented by showing that it rendered the cells 1.9-fold resistant to CuSO(4) and 4.1-fold resistant to DDP and also reduced the accumulation of both drugs. There was greater sequestration of Pt into intracellular vesicles in the 2008/ECFP-ATP7B cells than in the 2008/ECFP cells. Confocal digital microscopy revealed that ECFP-ATP7B localized in the perinuclear region in absence of drug exposure and that both Cu and DDP triggered relocalization to more peripheral vesicular structures. A fluorescein-labeled form of DDP that retained cytotoxicity and was subject to the same mechanisms of resistance as DDP colocalized with ECFP-ATP7B in the 2008/ECFP-ATP7B cells, whereas the same fluorochrome lacking the DDP moiety did not. These results provide evidence that DDP directly interacts with ATP7B to trigger its relocalization and that ATP7B mediates resistance to DDP by sequestering it into vesicles of the secretory pathway for export from the cell.

The copper influx transporter human copper transport protein 1 regulates the uptake of cisplatin in human ovarian carcinoma cells.

Cells selected for resistance to cisplatin are often cross-resistant to copper and vice versa, and the major copper influx transporter copper transport protein 1 (CTR1) has been shown to regulate the uptake of cisplatin, carboplatin, and oxaliplatin in yeast. To further define the role of hCTR1 in human tumor cells, the ovarian carcinoma cell line A2780 was molecularly engineered to increase expression of hCTR1 by a factor of 20-fold. Enhanced expression of hCTR1 in the A2780/hCTR1 cells was associated with a 6.5-fold increase in basal steady-state copper content and a 13.7-fold increase in initial copper influx, demonstrating that the exogenously expressed hCTR1 was functional in altering copper homeostasis. The A2780/hCTR1 cells accumulated 46% more platinum after a 1-h exposure to 2 microM cisplatin, and 55% more after a 24 h exposure, than the control A2780/empty vector cells. The initial uptake of cisplatin was 81% higher in the A2780/hCTR1 cells when measured at 5 min. Thus, increased expression of hCTR1 had a substantially larger effect on the cellular pharmacology of copper than cisplatin. Interestingly, the increased uptake of copper and cisplatin was accompanied by only a marginal increase in sensitivity to the cytotoxic effect of copper and cisplatin, and there was no increase in the extent of cisplatin-DNA adduct formation. Thus, although increased expression of hCTR1 mediates greater cellular accumulation of copper and cisplatin, hCTR1 delivers these compounds into intracellular compartments from which they do not have ready access to their key cytotoxic targets.

Modulation of the cellular pharmacology of cisplatin and its analogs by the copper exporters ATP7A and ATP7B.

The copper efflux transporters ATP7A and ATP7B sequester intracellular copper into the vesicular secretory pathway for export from the cell. The influence of these transporters on the pharmacodynamics of cisplatin, carboplatin, and oxaliplatin was investigated using human Menkes' disease fibroblasts (Me32a) that do not express either transporter and sublines molecularly engineered to express either ATP7A (MeMNK) or ATP7B (MeWND). Cellular copper levels were significantly higher in the Me32a cells than in the MeMNK and MeWND sublines. These transporter-proficient sublines were resistant to the cytotoxic effect of copper, cisplatin, and carboplatin but were hypersensitive to oxaliplatin. Whole-cell accumulation of platinum after a 24-h exposure was significantly increased in the MeMNK and MeWND cells for all three platinum drugs, but this was accompanied by an increase in the amount of platinum reaching the DNA only for oxaliplatin. Vesicles isolated from MeMNK cells contained more platinum after exposure to cisplatin and carboplatin, whereas the platinum content of vesicles from MeWND cells was increased after exposure to all three drugs. Although copper triggered relocalization of ATP7A from the perinuclear region to more peripheral locations, the platinum drugs did not. These results demonstrate that both ATP7A and ATP7B modulate the pharmacodynamics of all three clinically used platinum drugs. The data are consistent with the hypothesis that these copper exporters sequester the platinum drugs into subcellular compartments, limiting their cytotoxicity, similar to their effect on copper. However, in this model system, although copper is readily exported after vesicular sequestration, the platinum drugs are not.

Cross-resistance to cisplatin in cells with acquired resistance to copper.

PURPOSE: Cells selected for resistance to cisplatin (DDP) demonstrate cross-resistance to copper (Cu) suggesting one or more common mechanisms of cellular defense. We sought to determine whether cells selected for resistance to Cu are cross-resistant to DDP. MATERIALS AND METHODS: Parental HuH7 human hepatoma cells and the CuR27 Cu-resistant subline were compared for sensitivity to Cu and DDP by clonogenic assay, and with respect to drug uptake and efflux by measuring cellular Cu and Pt content. RESULTS: CuR27 cells were found to be 1.8-fold resistant to Cu and 8.6-fold cross-resistant to DDP. Changes in the cellular pharmacokinetics of Cu in the CuR27 cells were paralleled by changes in the kinetics of DDP. The accumulations of Cu and DDP measured at 1 min were, respectively, 36% and 26% of those in the parental HuH7 cells. The initial rate of efflux from the CuR27 cells was 6.2-fold faster for Cu and 2.5-fold faster for DDP than from the HuH7 cells. Cu reduced the accumulation of DDP in the HuH7 cells in a concentration-dependent manner and vice versa. DDP also reduced the efflux of Cu. Western blot analysis demonstrated that expression of the Cu exporter ATP7B was increased 3.9-fold in the CuR27 cells. CONCLUSIONS: In this model system, cross-resistance between Cu and DDP was bidirectional and accompanied by parallel changes in the cellular pharmacokinetics of both compounds. The results are consistent with the idea that transporters and chaperones that normally mediate Cu homeostasis also directly or indirectly modulate the accumulation of DDP.

The copper export pump ATP7B modulates the cellular pharmacology of carboplatin in ovarian carcinoma cells.

Human tumor cells lines with acquired resistance to cisplatin (DDP) and carboplatin (CBDCA) are often cross-resistant to copper and vice versa, and some DDP-resistant cells overexpress the copper export pump ATP7B. We sought to demonstrate that ATP7B directly mediates resistance to DDP and CBDCA by stably transfecting human carcinoma cells with a vector designed to express ATP7B. Increased expression of ATP7B rendered all three cell lines tested more resistant to a 1-h exposure to DDP (1.6-2.6-fold), CBDCA (1.5-1.6-fold), and copper (1.2-1.4-fold). The effect of ATP7B on the cellular pharmacology of 64Cu and [14C]CBDCA was investigated in more detail using one cell pair (2008 cells transfected with an empty vector or an ATP7B-expressing vector). In the 2008/ATP7B subline, steady-state copper levels were decreased under both basal and copper-supplemented conditions, as was steady-state CBDCA content upon exposure to 50 microM [14C]CBDCA. Over the first 5 min, the average rate of accumulation of copper and CBCDA in the 2008/ATP7B cells was reduced by 37 and 61%, respectively. Efflux was more rapid from 2008/ATP7B cells for both copper and CBDCA. Two-compartment modeling indicated that the second phase of efflux was increased by a factor of 3.9-fold for CBCDA and to an even greater extent for copper. We conclude that expression of ATP7B regulates sensitivity to CBDCA as well as to DDP and copper and that a transporter that normally mediates copper homeostasis modulates the cellular pharmacology of CBDCA.

Acquisition of resistance to cisplatin is accompanied by changes in the cellular pharmacology of copper.

Impaired uptake of cisplatin (DDP) consistently accompanies the acquisition of resistance to the platinum drugs. The pathways by which DDP enters or exits from cells remain poorly defined. Using three pairs of human ovarian carcinoma cell lines, each consisting of a sensitive parental line and a stably DDP-resistant subline derived by in vitro selection, resistance to DDP was found to be accompanied by cross-resistance to Cu. Accumulation of DDP in the resistant sublines ranged from 38 to 67% of that in the parental line at 1 h, and DNA adduct formation varied from 10 to 38% of that in the sensitive cells. The DDP-resistant cells had 22-56% lower basal levels of copper, and the copper levels were only 27-46% of those observed in the sensitive parental lines after a 24-h exposure to medium supplemented with copper. The initial influx rate for DDP in the three resistant cell lines ranged from 23 to 55% of that in the sensitive cells of each pair; the initial influx rate for copper in the resistant cells varied from 56 to 75% of control. Studies performed using one pair of cell lines demonstrated that for both copper and DDP the initial efflux rate was lower, whereas the terminal efflux rate was higher in the resistant cells. On Western blot analysis all three resistant lines exhibited increased expression of one or the other of the two copper export pumps (ATP7A or ATP7B) with no change in the HAH1 chaperone. We conclude that the acquisition of DDP resistance in ovarian carcinoma is accompanied by alterations in the cellular pharmacology of DDP that are paralleled by similar changes in the uptake and efflux of copper. These results are consistent with the concept that DDP enters and exits from the cell via transporters that normally mediate copper homeostasis.