Expression of P-glycoprotein in hepatocellular carcinoma. A determinant of chemotherapy response

Effect of apoptotic and proliferative indices, P-glycoprotein and survivin expression on prognosis in laryngeal squamous cell carcinoma

This study was to explore the relationship between P-glycoprotein and survivin expression with apoptotic index, proliferative index, clinicopathologic characteristics, and their prognostic value in laryngeal squamous cell carcinoma (LSCC). Samples from 86 patients with LSCC were analyzed for P-glycoprotein, survivin, and Ki-67 expression by immunohistochemistry and apoptotic index by the TUNEL method. The association of P-glycoprotein and survivin expression with clinicopathologic parameters, apoptotic and proliferative activities, and patients' overall survival was subsequently analyzed. We found that up-regulation of P-glycoprotein expression was associated with decreased apoptosis but not with changes in proliferation, whereas increased survivin expression was correlated with decreased apoptosis and increased proliferation. There was a positive correlation between P-glycoprotein and survivin expression. Expression of these two proteins was significantly related to the clinical stage, histological grade, lymph node metastasis, and overall survival in LSCC. These results reveal that survivin and P-glycoprotein may have an effect on chemotherapy resistance and progression of LSCC through promoting proliferation and/or suppressing apoptosis. Furthermore, our results demonstrate that P-glycoprotein and survivin proteins are both predictive of malignant progression and prognosis of LSCC.

Expression of Drug-Resistant Factor Genes in Hepatocellular Carcinoma Patients Undergoing Chemotherapy with Platinum Complex by Arterial Infusion

This study investigated gene expression of drug resistance factors in biopsy tissue samples from hepatocellular carcinoma (HCC) patients undergoing chemotherapy by platinum complex. Liver biopsy was performed to collect tissue from the tumor site (T) and the non-tumor site (NT) prior to the start of treatment. For drug-resistant factors, drug excretion transporters cMOAT and MDR-1, intracellular metal binding protein MT2, DNA repair enzyme ERCC-l and inter-nucleic cell transport protein MVP, were investigated. The comparison of the expression between T and NT indicated a significant decrease of MT2 and MDR-1 in T while a significant increase in ERCC-1 was noted in T. Further, expression was compared between the response cases and non-response cases using the ratios of expression in T to those in NT. The response rate was significantly low in the high expression group when the cutoff value of cMOAT and MT2 was set at 1.5 and 1.0, respectively. Furthermore, when the patients were classified into A group (cMOAT ≧ 1.5 or MT2 ≧ 1.0) and B group (cMOAT < 1.5 and MT2 < 1.0), the response rate of A group was significantly lower than B group when we combined the cutoff values of cMOAT and MT2. It is considered possible to estimate the therapeutic effect of platinum complex at a high probability by combining the expression condition of these two genes.

Molecular mechanism of chemoresistance by astrocyte elevated gene-1

Our recent findings show that astrocyte elevated gene-1 (AEG-1) is overexpressed in >90% of human hepatocellular carcinoma (HCC) samples, and AEG-1 plays a central role in regulating development and progression of HCC. In the present study, we elucidate a molecular mechanism of AEG-1-induced chemoresistance, an important characteristic of aggressive cancers. AEG-1 increases the expression of multidrug resistance gene 1 (MDR1) protein, resulting in increased efflux and decreased accumulation of doxorubicin, promoting doxorubicin resistance. Suppression of MDR1 by small interfering RNA or chemical reagents, or inhibition of AEG-1 or a combination of both genes, significantly increases in vitro sensitivity to doxorubicin. In nude mice xenograft studies, a lentivirus expressing AEG-1 short hairpin RNA, in combination with doxorubicin, profoundly inhibited growth of aggressive human HCC cells compared with either agent alone. We document that although AEG-1 does not affect MDR1 gene transcription, it facilitates association of MDR1 mRNA to polysomes, resulting in increased translation, and AEG-1 also inhibits ubiquitination and subsequent proteasome-mediated degradation of MDR1 protein. This study is the first documentation of a unique aspect of AEG-1 function (i.e., translational and posttranslational regulation of proteins). Inhibition of AEG-1 might provide a means of more effectively using chemotherapy to treat HCC, which displays inherent chemoresistance with aggressive pathology.

Hepatic cancer stem cells and drug resistance: Relevance in targeted therapies for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of most common malignancies in the world. Systemic treatments for HCC, particularly for advanced stages, are limited by the drug resistance phenomenon which ultimately leads to therapy failure. Recent studies have indicated an association between drug resistance and the existence of the cancer stem cells (CSCs) as tumor initiating cells. The CSCs are resistant to conventional chemotherapies and might be related to the mechanisms of the ATP Binding Cassette (ABC) transporters and alterations in the CSCs signaling pathways. Therefore, to contribute to the development of new HCC treatments, further information on the characterization of CSCs, the modulation of the ABC transporters expression and function and the signaling pathway involved in the self renewal, initiation and maintenance of the cancer are required. The combination of transporters modulators/inhibitors with molecular targeted therapies may be a potent strategy to block the tumoral progression. This review summarizes the association of CSCs, drug resistance, ABC transporters activities and changes in signaling pathways as a guide for future molecular therapy for HCC.

Apparent remission of a solitary metastatic pulmonary lesion in a liver transplant recipient treated with sorafenib

Hepatocellular carcinoma (HCC) remains a significant disease worldwide and its incidence is expected to increase. In selected patients, liver transplantation offers a 5-year patient survival between 48% and 75%. However, HCC recurrence occurs in approximately 20% of transplant recipients. No therapy has proven efficacious in decreasing the risk of recurrence after transplantation. Sorafenib, a multitargeted tyrosine kinase inhibitor, has been shown to improve survival in patients with advanced HCC that have no history of liver transplantation. We report complete remission of HCC in a 54-year-old man who developed biopsy-proven lung metastasis after liver transplantation treated with sorafenib.

Drug-metabolising enzymes are down-regulated by hypoxia in differentiated human hepatoma HepaRG cells: HIF-1alpha involvement in CYP3A4 repression

Weak blood irrigation within solid tumours including hepatocellular carcinomas (HCCs) plays an important role in resistance to anticancer drugs by decreasing accessibility of cytotoxic agents to tumour cells. Reduced oxygen levels, or hypoxia, also contribute to drug resistance because many anticancer drugs require molecular oxygen to be cytotoxic. Our aim was to develop a new in vitro model mimicking hypoxic cells within HCCs in order to further explore the molecular responses to hypoxia, including regulation of drug-metabolising enzymes (DMEs) expression. For this purpose, we used the highly differentiated human hepatoma HepaRG cells cultured under either normoxic or hypoxic (24h at 1% O(2)) conditions. Gene and protein expressions were investigated by quantitative PCR and immunoblotting, respectively. We showed that HepaRG cells adapt to prolonged moderate hypoxia by a switch from aerobic to anaerobic glycolysis and a repression of critical genes involved in amino acid, lipid and ethanol metabolisms. Importantly, expression of several DMEs (particularly cytochromes P450 (CYPs) and phase II enzymes) and xenosensors (CAR, PXR and AhR) was down-regulated and CYPs activities (using testosterone and paclitaxel as substrates) were decreased during hypoxia. In addition, a new role for HIF-1alpha in the repression of CYP3A4 is demonstrated in cells treated with chemical inducers of HIF-1alpha, cobalt chloride or desferrioxamine, and by transfecting untreated HepaRG cells with HIF-1alpha expression vector. In conclusion, HepaRG cells cultured under hypoxia might mimic metabolic changes occurring within poorly irrigated differentiated HCCs. Furthermore, hypoxia down-regulates hepatic DMEs, a phenomenon that might compromise chemotherapy effectiveness in HCC treatment. Thus, HepaRG cells might represent a new in vitro model to test anticancer agents in hypoxic versus normoxic conditions.

Molecular targeted therapy for hepatocellular carcinoma

A majority of patients with HCC present with advanced disease and are not candidates for liver transplantation, surgical resection, or regional therapy. Systemic cytotoxic chemotherapy agents are minimally effective, can have significant toxicity, and have not been shown to improve patient survival. Hepatocellular carcinomas are inherently chemotherapy-resistant tumors and are known to overexpress the multidrug resistance genes. Hepatocellular carcinoma is a very heterogeneous disease in terms of its etiology, molecular carcinogenic mechanisms, and biological behavior, which complicate our ability to identify rational molecular therapeutic "targets." Nearly every pathway involved in carcinogenesis is altered to some degree in HCC. Changes in hepatocyte growth factor expression, intracellular signaling, protease and matrix metalloproteinase expression, and oncogene expression are seen in HCC. The recent demonstration, in randomized clinical trials, of survival benefit for HCC patients treated with the oral agent sorafenib is encouraging progress in the development of molecularly targeted anticancer agents in HCC.

Expression of multidrug resistance-associated protein 1 in hepatocellular carcinoma is associated with a more aggressive tumour phenotype and may reflect a progenitor cell origin

BACKGROUND

Hepatocellular carcinoma (HCC) responds poorly to chemotherapy owing to multidrug resistance (MDR). Recent studies showed that part of HCC could be of progenitor cell origin. Because some MDR-conferring transporters [multidrug resistance-associated protein 1 (MRP1), MDR1, MRP3 and breast cancer resistance protein (BCRP)] are expressed in hepatic progenitor cells (HPCs), expression in HCC might reflect a progenitor cell origin and provide the tumour cells with a MDR phenotype.

METHODS

The transcriptional profile of transporter genes was assessed in 139 HCCs earlier subjected to global gene expression analysis. In addition, we performed real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry for MRP1, MRP3, MDR1, BCRP and biliary/HPC markers keratin 7 and/or keratin 19 (K7/K19) on an independent set of 23 HCCs and surrounding liver.

RESULTS

Micro-array analysis showed that MRP1 was the only transporter with increased mRNA levels in HCC compared with the surrounding tissue. MRP1 mRNA levels were significantly higher in HCCs with poor survival and the 'hepatoblast subtype' of HCC, thought to be derived from HPCs. In 11 of 23 HCCs of the independent set, we found a diffuse protein expression of MRP1 compared with negative hepatocytic expression observed in normal (surrounding) hepatocytes. MRP1 was expressed in K19(+) non-neoplastic HPCs and K19(+) tumour cells. In addition, MRP3 and BCRP were expressed in K7/K19(+) tumour cells. MRP1 expression was high in poorly differentiated HCCs, large tumours (>7 cm) and microvascular invasive tumours.

CONCLUSIONS

MRP1 correlated with K19 mRNA and protein expression in two independent series of HCC. In addition, MRP1 was, together with MRP3 and BCRP, colocalized with K7/K19 in the tumour. Therefore, MRP1 expression could be a reflection of the HPC origin of this subgroup of HCCs and may result in an aggressive tumour phenotype.

Evolution of systemic therapy of advanced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) commonly occurs in hepatitis B endemic areas, especially in Asian countries. HCC is highly refractory to cytotoxic chemotherapy. This resistance is partly related to its tumor biology, pharmacokinetic properties, and both intrinsic and acquired drug resistance. There is no convincing evidence thus far that systemic chemotherapy improves overall survival in advanced HCC patients. Other systemic approaches, such as hormonal therapy and immunotherapy, have also disappointing results. Recently, encouraging results have been shown in using sorafenib in the treatment of advanced HCC patients. In this review, we concisely summarize the evolution of developments in the systemic therapy of advanced HCC.

Systemic therapy of hepatocellular carcinoma: are we making progress?

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and the third most common cause of cancer deaths. Surgical resection, with or without transplantation, can result in long-term survival. However, surgery can only be performed in about 15% of patients with HCC and the 5-year survival rate is only approximately 33%-50% after potentially curative resection. Percutaneous ethanol injection, radiofrequency ablation, and transarterial chemoembolization are invasive techniques that have shown efficacy in reducing tumor bulk. Similarly, systemic chemotherapy may induce tumor responses, but a survival benefit has not been clearly demonstrated. In addition, the lack of efficacy of antiandrogens, tamoxifen, and single-agent interferon has now been confirmed.Sorafenib is a multikinase inhibitor with antiangiogenic, proapoptotic, and Raf kinase inhibitory activity. In a large, multicenter, randomized, phase 3 trial there was a significant improvement in both time to disease progression and overall survival with sorafenib compared with placebo. Sorafenib is the first agent to demonstrate a consistent improvement in overall survival for patients with advanced HCC. Further studies are required to determine the role of other molecular-targeted therapies, either alone or in combination with sorafenib in patients with advanced HCC. Further studies are also required to determine the role of sorafenib in combination with locoregional therapies (eg, transarterial chemoembolization), and the role of sorafenib as adjuvant therapy following surgery.

Systemic therapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is currently the fifth most common solid tumor worldwide and the third leading cause of cancer-related death. Eighty percent of new cases occur in developing countries, but the incidence is rising in economically developed regions including Japan, Western Europe, and the United States. More than 80% of patients present with advanced or unresectable disease, and for those patients who do undergo resection, the recurrence rates can be as high as 50% at 2 years. Thus, a large number of patients will seek systemic therapy. Systemic cytotoxic chemotherapy is largely ineffective and can have significant toxicity in patients with underlying liver dysfunction. Newer biologic agents that target molecular abnormalities common to HCC may improve the clinical outcome in patients with HCC.

Efficacy and safety of epirubicin and etoposide combination chemotherapy in advanced hepatocellular carcinoma: a retrospective analysis

BACKGROUND AND AIM

Systemic treatments of advanced hepatocellular carcinoma (AHCC) have offered marginal clinical benefits. Recently, Italian investigators reported that etoposide and epirubicin combination (EE) chemotherapy was highly active against AHCC, with a response rate of 39% and a median overall survival (OS) of 10 months. We report our efficacy and safety results of EE in clinical practice.

METHODS

Between December 1999 and October 2005, 35 patients with AHCC and fitting the preset eligibility criteria were treated with EE. Twenty-eight patients (80%) had liver disease associated with hepatitis B virus (HBV) and 26 (74%) had a prior history of transarterial chemoembolization (TACE) using cisplatin. The EE chemotherapy consisted of epirubicin 40 mg/m(2) on day 1 and etoposide 120 mg/m(2) on days 1, 3 and 5 every 4 weeks.

RESULTS

A total of 102 chemotherapy cycles were administered, with a median of two cycles per patient (range one to eight cycles). Two patients had a partial response and nine had stable disease, with a tumor control rate of 32% (95% CI 17-48). The median progression-free survival (PFS) was 2.1 months (95% CI 1.8-2.4) and the median OS was 6.4 months (95% CI 4.4-8.5). There was a tendency toward improved PFS in patients seronegative for HBsAg and peritoneal seeding (P = 0.06 and P = 0.054, respectively). Overall survival was significantly better in patients without HBsAg and Cancer Liver Italian Program (CLIP) score 0-1 (P = 0.024 and P = 0.033, respectively). The main toxicities were hematological events, including grade 3/4 neutropenia in 29% and febrile neutropenia in 11% of patients.

CONCLUSION

Treatment with EE showed minimal antitumor activity with acceptable toxicity in HBV-associated AHCC, especially in patients pretreated with TACE.

Systemic therapy for hepatocellular carcinoma: cytotoxic chemotherapy, targeted therapy and immunotherapy

Conventional cytotoxic chemotherapy has not provided clinical benefit or prolonged survival for patients with advanced HCC. This review summarizes the results of prospective clinical trials of several categories of systemic therapy, with emphasis on the more promising results from recent trials of biologically targeted therapeutic agents in HCC.

In vivo evaluation of lipid nanocapsules as a promising colloidal carrier for paclitaxel

Paclitaxel-loaded lipid nanocapsules (PX-LNC) exhibit interesting in vitro characteristics with improved antitumoral activity compared with free PX formulation. Biodistribution studies were realized with the use of (14)C-trimyristin ((14)C-TM) or (14)C-phosphatidylcholine ((14)C-PC) whereas antitumoral activity of PX-LNC formulations was based on the animal survival in a chemically induced hepatocellular carcinoma (HCC) model in Wistar rats. Blood concentration-time profiles for both labeled (14)C-TM-LNC and (14)C-PC-LNC were similar; the t(1/2) and MRT values (over 2h and close to 3h, respectively, for both formulations) indicated the long circulating properties of the LNC carrier with a slow distribution and elimination phase. Survival curves of paclitaxel treated groups showed a statistical significant difference compared to the control survival curve (P=0.0036 and 0.0408). Animals treated with 4x 70 mg/m(2) of PX-LNC showed the most significant increase in mean survival times compared to the controls (IST(mean) 72%) and cases of long-term survivors were preferentially observed in the PX-LNC treated group (37.5%; 3/8). These results demonstrate the great interest to use LNC as drug delivery system for paclitaxel, permitting with an equivalent therapeutic efficiency to avoid the use of excipients such as polyoxyethylated castor oil for its formulation.

Fluorine-18 fluorodeoxyglucose positron emission tomography predicts tumor differentiation, P-glycoprotein expression, and outcome after resection in hepatocellular carcinoma

PURPOSE

To investigate the diagnostic value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for prediction of tumor differentiation, P-glycoprotein (P-gp) expression, and outcome in hepatocellular carcinoma (HCC) patients.

EXPERIMENTAL DESIGN

Seventy HCC patients who underwent curative resection were prospectively enrolled in the study. FDG-PET was done 2 weeks preoperatively, and the standardized uptake value (SUV) and the tumor to nontumor SUV ratio (TNR) were calculated from FDG uptake. Tumor differentiation and P-gp expression were examined with H&E and immunohistochemical staining, respectively.

RESULTS

SUV and TNR were significantly higher in poorly differentiated HCCs than in well-differentiated (P = 0.001 and 0.002) and moderately differentiated HCCs (P < 0.0001 and P < 0.0001). The percentage P-gp-positive area was significantly higher in well-differentiated HCCs than in poorly differentiated (P < 0.0001) and moderately differentiated HCCs (P = 0.0001). Inverse correlations were found between SUV and P-gp expression (r = -0.44; P < 0.0001) and between TNR and P-gp expression (r = -0.47; P = 0.01). Forty-three (61.4%) patients had postoperative recurrence. The overall and disease-free survival rates in the high TNR (> or =2.0) group were significantly lower than in the low TNR (<2.0) group (P = 0.0001 and 0.0002). In multivariate analysis, a high alpha-fetoprotein level (risk ratio, 5.46; P = 0.003; risk ratio, 8.78; P = 0.006) and high TNR (risk ratio, 1.3; P = 0.03; risk ratio, 1.6; P = 0.02) were independent predictors of postoperative recurrence and overall survival.

CONCLUSIONS

The results suggest that preoperative FDG-PET reflects tumor differentiation and P-gp expression and may be a good predictor of outcome in HCC.

Multifactorial nature of hepatocellular carcinoma drug resistance: could plant polyphenols be helpful?

Primary hepatocellular carcinoma (HCC) is a quite frequent tumor which results in high mortality and most often exhibits a poor response to present drug therapies. Clearly, a thorough understanding of the biological bases of this malignancy might suggest new strategies for its treatment. Here we examine the evidences that both "pharmacological" mechanisms (e.g. drug transporter or detoxification enzyme over-expression) and alterations in other critical factors, including the IAPs (Inhibitory of Apoptosis Proteins), involved in enhancement of cell survival and proliferation may determine the therapeutic resistance of HCC; we also underline the possible role in the process of the activation of transcription factors, like NF-kappaB, capable of contemporaneously up-regulating the mechanisms discussed. On this basis, we finally comment on the possible use of natural multi-targeted antitumoral agents like plant polyphenols to achieve sensitization to treatments in HCC.

Gemcitabine plus oxaliplatin (GEMOX) in patients with advanced hepatocellular carcinoma (HCC)

BACKGROUND

New systemic therapies are needed to improve the prognosis of patients with advanced-stage hepatocellular carcinoma (HCC). In a Phase II trial involving previously untreated patients with advanced HCC, the more favorable schedule from a previous pilot study was evaluated.

METHODS

Thirty-four patients with previously untreated advanced-stage HCC were prospectively enrolled. The GEMOX regimen consisted of gemcitabine 1000 mg/m(2) on Day 1 and oxaliplatin 100 mg/m(2) on Day 2. The treatment was repeated every 2 weeks until disease progression or limiting toxicity.

RESULTS

Thirty-two patients were assessable for efficacy and 33 for toxicity. In all, 323 treatment cycles were administered. No toxic deaths occurred. Hematological grade 3-4 toxicity consisted of thrombocytopenia (27% of patients) and neutropenia (24%), including 2 febrile neutropenia and anemia (9%). Grade 3 oxaliplatin-induced neurotoxicity was observed in 3 (9%) patients. The overall response rate was 18% (95% confidence interval [CI]: 8-34) and disease stabilization was observed in 58% of patients (including 5 minor responses), giving a disease control rate of 76%. Median progression-free and overall survival times were, respectively, 6.3 months (95% CI: 4.3-10.1 months) and 11.5 months (95% CI: 8.5-14.3 months). Treatment was significantly more effective in patients with nonalcoholic cirrhosis than in those with alcoholic cirrhosis.

CONCLUSIONS

The GEMOX regimen seems to be well tolerated and active in advanced HCC, especially in patients with underlying nonalcoholic liver disease. A Phase II study of the GEMOX regimen plus cetuximab is ongoing.

Relationship between therapeutic efficacy of arterial infusion chemotherapy and expression of P-glycoprotein and p53 protein in advanced hepatocellular carcinoma

AIM: To investigate the relationship between the chemotherapeutic drug efficacy and the expression of P-glycoprotein (PGP) and p53 protein in advanced hepatocellular carcinoma (HCC).

METHODS: The study was conducted on 41 patients with advanced HCC who were treated by repeated arterial infusion chemotherapy. Biopsy specimens from the tumor were collected before the start of treatment in all the patients, and the specimens were stored frozen until immunohistochemical staining, which was performed after the start of treatment, to detect PGP and p53 protein expressions. Twenty of the forty-one patients were treated with an anthracycline drug (epirubicin hydrochloride; anthracycline group), and the remaining 21 were treated with a non-anthracycline drug (mitoxantrone hydrochloride in 11 patients and carboplatin in 10 patients; non-anthracycline group). The relationship between the chemotherapeutic efficacy and the results of immunostaining were compared between the two groups.

RESULTS: Before the start of the treatment, PGP-positive rate was 90.2% (strongly-positive, 36.6%) and p53 protein-positive rate was 34.1% (strongly-positive, 19.5%). In the anthracycline group, the response rate was 40.0%. The number of patients showing poor response to the treatment was significantly larger in the patients with strongly positive PGP expression (P = 0.005), and their prognoses were poor (P = 0.001). In the non-anthracycline group, the response rate was 42.9%, and there was no significant relationship between the chemotherapeutic drug efficacy and the PGP or p53 protein expression. When only the data from the 11 patients treated with anthraquinone drug, mitoxantrone, were analyzed, however, the number of patients who showed poor response to treatment was significantly higher among the p53-positive patients (P = 0.012), irrespective of the survival outcome.

CONCLUSION: The chemotherapeutic efficacy with an anthracycline drug for advanced HCC can be predicted by immunohistochemical analysis of PGP expression. Similarly, immunostaining to evaluate p53 protein may be useful to predict the response in patients treated with an anthraquinone drug.

Increase of doxorubicin sensitivity by doxorubicin-loading into nanoparticles for hepatocellular carcinoma cells in vitro and in vivo

BACKGROUND/AIMS

Hepatocellular carcinoma (HCC) is known to be chemoresistant to anticancer drugs due to the multidrug resistant (MDR) transporters expression. Here, we compared in vitro and in vivo the anti-tumor efficacy of doxorubicin-loaded polyisohexylcyanoacrylate nanoparticles (PIHCA-Dox) versus free doxorubicin (Dox). These nanoparticles are known to overcome the MDR phenotype.

METHODS

We first determined in vitro the 50% inhibition concentration (IC(50)) of these drugs on different human hepatoma cell lines. Secondly, the efficacy of the drugs in vivo was determined on the X/myc transgenic murine model of HCC by histological counting of apoptotic tumorous hepatocytes and by TUNEL labeling. We characterized by semi-quantitative RT-PCR the MDR-related gene (mdr1, mdr3, mrp1) expression pattern in this model.

RESULTS

In vitro, IC(50) was reduced with PIHCA-Dox versus Dox for Huh7 (1.7-fold reduction; P<0.001), HepaRG (4.5-fold reduction; P<0.01), HepG2 (1.5-fold reduction; P<0.001), and HepG2.2.15 (1.5-fold reduction; P=0.059). In vivo, HCC in transgenic mice overexpressed the mdr1 and mdr3 genes and the antitumor drugs efficacy was greatly enhanced after injection of PIHCA-Dox (9.0+/-5.0%; n=15) versus Dox (4.6+/-3.3%; n=13; P=0.01) for apoptotic bodies count.

CONCLUSIONS

These promising data showing a higher anti-tumor efficacy on HCC of PIHCA-Dox versus Dox, warrant further studies in both animals and humans.

Hepatobiliary transporter expression in human hepatocellular carcinoma

BACKGROUND/AIMS

Treatment of hepatocellular carcinoma (HCC) is hampered by resistance to chemotherapy, which might be mediated by multidrug resistance P-glycoproteins (MDR P-gps) and MDR-associated proteins (MRPs). The effectiveness of cytostatics could be further impeded by reduced hepatocellular drug uptake into HCCs. Therefore, we aimed to determine P-gp, MRP and organic anion transporting protein OATP2 (SLC21A6) expression in HCC. Furthermore, we investigated expression of the major bile salt uptake system Na(+)/taurocholate cotransporter NTCP (SLC10A1), since bile salt-coupled chemotherapeutics were proposed to increase therapeutic drug enrichment in HCC.

MATERIAL/METHODS

mRNA and protein expression and tissue distribution of P-gps, MRPs, OATP2 and NTCP were assessed in HCC and peritumorous non-neoplastic tissue by reverse transcription polymerase chain reaction, Western blotting and immunohistochemistry, respectively.

RESULTS

Expression of P-gps (multidrug export pump MDR1 (ABCB1), phospholipid flippase MDR3 (ABCB4), sister of P-glycoprotein SPGP (ABCB11)) and basolateral MRP homologue MRP3 (ABCC3) showed a trend for decreased levels in HCC but was highly variable among individual tumors. In contrast, canalicular conjugate export pump MRP2 (ABCC2) expression was generally maintained or even showed a trend towards increased levels. NTCP and OATP2 expression was markedly reduced in most HCCs (P < 0.05). Expression of the genuine drug transporter, the concentrative nucleoside transporter (CNT1), was highly variable and showed a trend for reduced levels in HCC.

SUMMARY/CONCLUSIONS

MRP2 seems to be the major candidate transporter involved in chemoresistance and reduced expression of OATP2 may further contribute to low drug accumulation in HCCs. Overexpression of drug exporters is not a general feature of HCC but could account for chemoresistance of individual cases. Since expression of uptake systems is generally reduced in HCC, bile salt-coupled therapeutics may not represent a suitable strategy to overcome insufficient drug enrichment.

Gemcitabine plus oxaliplatin for patients with advanced hepatocellular carcinoma using two different schedules

BACKGROUND

New therapies are needed to improve the prognosis of patients with advanced hepatocellular carcinoma (HCC). Various gemcitabine-oxaliplatin combinations have been tested recently in patients with ovarian and pancreatic carcinoma, yielding interesting results with little toxicity. Therefore, the authors evaluated the activity and toxicity of two such combinations in patients with HCC.

METHODS

Twenty-one patients were enrolled prospectively in the study. Eleven patients received gemcitabine 1000 mg/m2 on Day 1 and oxaliplatin 100 mg/m2 on Day 2 (GEMOX-1), and 10 patients received gemcitabine 1500 mg/m2 on Day 1 followed by oxaliplatin 85 mg/m2 on Day 1 (GEMOX-2). Treatment was repeated every 2 weeks until disease progression developed or until unacceptable adverse effects occurred.

RESULTS

All patients were assessable for response and toxicity. Four patients (19%) achieved objective responses (95% confidence interval, 13-26%), including 3 patients in the GEMOX-1 group and 1 patient in the GEMOX-2 group. Ten patients (48%) had stable disease, and 7 patients (33%) experienced disease progression. The median progression-free survival was 5 months, and the median overall survival was 12 months. Fifty-four percent of patients in the GEMOX-1 group and 50% of patients in the GEMOX-2 group had received previous systemic chemotherapy or cisplatin-based chemoembolization. Grade 3-4 hematologic toxicity, according to National Cancer Institute Common Toxicity Criteria, consisted of thrombocytopenia (GEMOX-1 vs. GEMOX-2, 18% vs. 40%) and neutropenia (0% vs. 30%). No Grade 3-4 nonhematologic toxicity was observed, except for 1 episode of Grade 3 diarrhea. Grade 1 neurotoxicity and Grade 2 neurotoxicity (specific scale), respectively, were observed in 4 patients and 7 patients receiving GEMOX-1 and in 7 patients and 1 patient receiving GEMOX-2.

CONCLUSIONS

Gemcitabine-oxaliplatin combination therapy is feasible in patients with advanced HCC. The GEMOX-1 regimen was tolerated better than the GEMOX-2 regimen. Currently, the GEMOX-1 regimen is being evaluated in a Phase II study in previously untreated patients with HCC.

Usefulness of technetium-99m tetrofosmin liver imaging to detect hepatocellular carcinoma and related to expression of P-glycoprotein or multidrug resistance associated protein-a preliminary report

Technetium-99m Tetrofsomin (Tc-TF) has been shown to be useful in identifying several types of tumors, such as breast, lung, and thyroid cancers. There was no report in the literature for Tc-TF uptake in hepatocellular carcinoma (HCC). The aim of this study was to evaluate the usefulness of Tc-TF liver imaging to detect HCC and investigate the relationship between Tc-TF liver imaging findings and P-glycoprotein (Pgp) and multidrug resistance associated protein (MRP) expression. Before any therapy, 22 patients with HCC were enrolled in this study. Tc-TF liver images were performed l0 minutes after intravenous injection of 20mCi Tc-TF. All patients had liver biopsy or surgery within l week after Tc-TF liver imaging. Immunohistochemical study of the biopsy or resected HCC specimens was performed using anti-human Pgp and MRP antibodies. Twenty of the 22 (90.9%) patients showed negative Tc-TF liver imaging results without significant Tc-TF uptake in HCC, whereas only the remaining 2 (9.1%) patients showed positive Tc-TF liver imaging results with significant Tc-TF uptake in HCC. Positive Pgp expression was observed in 13 of 20 patients with negative Tc-TF liver imaging results, whereas positive MRP expression was observed in 6 of the remaining 7 patients with negative both Tc-TF liver imaging results and Pgp expression. However, negative Pgp expression but positive MRP expression was observed in all of the remaining 2 patients with positive Tc-TF liver imaging results. The correlation between Tc-TF liver imaging findings and Pgp expression was significant and better than between Tc-TF liver imaging findings and MRP expression. Pgp or MRP expression in HCC may induce no significant Tc-TF uptake in HCC resulting in negative Tc-TF liver imaging findings. Therefore, Tc-TF liver imaging is potential to be a non-invasive method to predict Pgp or MRP expression in HCC. However, further studies with a larger series of patients and longer follow-up time are necessary to confirm our findings.

cDNA microarray analysis of macroregenerative and dysplastic nodules in end-stage hepatitis C virus-induced cirrhosis

Hepatocellular carcinoma is a common malignancy causing significant morbidity and mortality worldwide. In this study we use expression microarray technology to identify novel genes that consistently displayed altered expression levels in the earliest identifiable precursors to hepatocellular carcinoma, dysplastic and macroregenerative nodules. The gene expression profiles from nine patients with end-stage hepatitis C cirrhosis that contained a combined 11 dysplastic or macroregenerative nodules were compared to the patient's matched cirrhotic liver tissue. A total of 53 genes were consistently dysregulated in the patient liver specimens. Six of seven genes were validated by quantitative real-time reverse transcriptase-polymerase chain reaction, or by immunohistochemical studies performed on an independent set of lesions. The novel genes, including caveolin-1, semaphorin E, and FMS-like tyrosine kinase 3 ligand, have putative roles in carcinogenesis but have not been reported in hepatocellular carcinogenesis. Microarray expression analysis of dysplastic and macroregenerative liver nodules provide insight into the earliest changes in hepatocellular carcinogenesis.

Cyclosporine a augments P-glycoprotein expression in the regenerating rat liver

In the liver, the multidrug resistance (MDR) protein P-glycoprotein (P-gp) is physiologically expressed at the bile canalicular membrane, where it participates in the biliary excretion of various lipophilic drugs and xenobiotics. Previous studies showed that the immunosuppressive agent cyclosporine A (CsA) modulates P-gp and exerts a hepatotrophic influence in the regenerating liver. Hepatocytes isolated from regenerating rat liver, after 2/3 partial hepatectomy (PH 2/3), were used as an in vivo experimental model of cells with high proliferating activity in order to investigate whether CsA influences cellular levels of P-gp in those cells. Male Wistar rats were treated with CsA (20 mg/kg body weight) for 4 d preoperatively and 1 d postoperatively, and regenerating hepatocytes were isolated by collagenase perfusion 12, 24 and 48 h after PH 2/3. Flow cytometry and Western blotting studies with the monoclonal antibodies C494 and C219 showed that after PH 2/3, cellular levels of P-gp were initially suppressed, 12 h after PH 2/3, by 23%, but were significantly elevated thereafter, 24 and 48 h after PH 2/3 by 28% and 73%, respectively. In CsA pretreated animals, P-gp levels were increased even in normal hepatocytes by 34%, and an additional augmentation was seen in hepatocytes from 24 and 48 h regenerating livers (60% and 56%, respectively). In summary, we demonstrate for the first time that CsA has an additive effect on the expression of P-glycoprotein during liver regeneration in the rat. Therefore, induction of P-gp might also be considered in patients receiving CsA after liver transplantation for hepatocellular carcinoma and chemotherapy as an adjuvant treatment for the prevention of tumor recurrence.

Hepatocellular carcinoma: systemic treatments

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, with increasing incidence in Western countries. Many pharmacologic treatments have been tested against HCC; most of them belong to three categories: chemotherapy, hormone therapy, and immunotherapy. Neither single agent nor combination chemotherapy have demonstrated a clear reproducible advantage in terms of overall survival; therefore, systemic or intraarterial chemotherapy should not be considered as standard strategies for patients with HCC. Tamoxifen and antiandrogen therapy were not effective in prolonging survival when tested in randomized, controlled trials. Promising results have been obtained with octreotide in a small randomized trial, but confirmation studies are needed. Although adoptive immunotherapy was effective in the adjuvant setting, interferon should be further investigated in this setting or investigated as a preventive strategy in cirrhotic patients. On the contrary, interferon does not seem to have a role in advanced disease, where it is tolerated poorly. In the future, innovative and promising therapeutic strategies will be tested in HCC, including new biologic target-based drugs, cyclooxygenase inhibitors, and gene therapy.

Reversal of drug resistance of hepatocellular carcinoma cells by adenoviral delivery of anti-MDR1 ribozymes

Human cancers, including hepatocellular carcinoma (HCC), are characterized by a high degree of drug resistance. The multidrug resistance (MDR) transporters MDR1-P-glycoprotein and MRP2 (multidrug-associated protein 2) are expressed in almost 50% of human cancers, including HCCs. In this study, we analyzed the effect of anti-MDR1 ribozymes, especially AFP promoter-driven anti-MDR1 ribozymes, to specifically chemosensitize HCC cells. Epirubicin-selected HB8065/R cells were used as MDR1-P-glycoprotein-overexpressing cells. Adenoviral vectors were constructed to allow an efficient gene transfer of anti-MDR1 ribozyme constructs. AFP promoter-driven anti-MDR1 ribozymes reduced the IC(50) 30-fold for epirubicin in HCC cells, whereas human colorectal cancer cells were unaffected. Target sequences were either the translational start site or codon 196 of the human MDR1 gene. Adenoviral delivery of CMV promoter-driven anti-MDR1 ribozymes resulted in a reduced IC(50) for epirubicin and doxorubicin (60- and 20-fold, respectively). They completely restored chemosensitivity in stably transfected anti-MDR1 ribozyme-expressing HCC cells as well as in HCC cells transduced with adenoviruses expressing wild-type anti-MDR1 ribozymes. Adenoviral delivery of ribozymes was so efficient that chemosensitization of HCC cells could be demonstrated in cell cultures without further selection of transduced cells for single anti-MDR1 ribozyme-expressing HCC cell clones. Northern blots showed a decreased MDR1 mRNA expression, and fluorescence-activated cell sorting (FACS) analysis revealed a significantly reduced expression of MDR1-P-glycoprotein on the cell surface of HB8065/R cells after transduction with the anti-MDR1 ribozymes. In conclusion, our data demonstrate that adenoviral delivery of ribozymes can chemosensitize HCC cells and that chemosensitization can be specifically achieved by ribozymes driven by an AFP promoter directed against human MDR1.

Polymorphisms in the ABC drug transporter gene MDR1

In addition to genetically variable metabolic enzymes such as Cyp p450 proteins, blood and tissue levels of many drugs are influenced by controlled transport across compartmental boundaries. Major determinants in these transport processes are ATP-dependent efflux pumps such as P-glycoprotein and related proteins (eg MRPs), which can influence the bioavailability and CNS concentrations, as well as disposition of drugs. In addition to its recognized role in the development of multiple chemotherapy resistances, experimental evidence for the relevant influence of the MDR1 gene encoded P-glycoprotein, on the pharmacology of many other drugs has been gathered by the analyses of knockout mice, as well as in clinical studies. Recently, functional genetic polymorphisms in the MDR1 gene have been identified which influence the distribution and bioavailability of PGP substrates.

Induction of human MDR1 gene expression by 2-acetylaminofluorene is mediated by effectors of the phosphoinositide 3-kinase pathway that activate NF-kappaB signaling

The expression of P-glycoprotein encoded by the multidrug resistance (MDR1) gene is associated with the emergence of the MDR phenotype in cancer cells. Human MDR1 and its rodent homolog mdr1a and mdr1b are frequently overexpressed in liver cancers. However, the underlying mechanisms are largely unknown. The hepatocarcinogen 2-acetylaminofluorene (2-AAF) efficiently activates rat mdr1b expression in cultured cells and in Fisher 344 rats. We recently reported that activation of rat mdr1b in cultured cells by 2-AAF involves a cis-activating element containing a NF-kappaB binding site located -167 to -158 of the rat mdr1b promoter. 2-AAF activates IkappaB kinase (IKK), resulting in degradation of IkappaBbeta and activation of NF-kappaB. In this study, we report that 2-AAF could also activate the human MDR1 gene in human hepatoma and embryonic fibroblast 293 cells. Induction of MDR1 by AAF was mediated by DNA sequence located at -6092 which contains a NF-kappaB binding site. Treating hepatoma cells with 2-AAF activated phosphoinositide 3-kinase (PI3K) and its downstream effectors Rac1, and NAD(P)H oxidase. Transient transfection assays demonstrated that constitutively activated PI3K and Rac1 enhanced the activation of the MDR1 promoter by 2-AAF. Treatment of hepatoma cells with 2-AAF also activated another PI3K downstream effector Akt. Transfection of recombinant encoding a dominant activated Akt also enhanced the activation of MDR1 promoter activation by 2-AAF. These results demonstrated that 2-AAF up-regulates MDR1 expression is mediated by the multiple effectors of the PI3K signaling pathway.

Cancer chemoresistance: the relationship between p53 and multidrug transporters

Extensive studies indicate that both p53 and multidrug transporters play important roles in chemoresistance. Since the initial reports a decade ago demonstrating a transcriptional dependence of the ABCB1 gene (MDR) promoter by p53, much data have been accumulated. However, despite being the subject of intense study, this p53-MDR relationship remains unclear in human cancers. The data are confounded by variable and contrasting results when considering the in vitro regulation and attempting to draw parallels in tissue specimens. The original model suggested that wild-type p53 downregulates the ABCB1 promoter, whereas mutant p53 increases expression of ABCB1. This review summarizes the data for and against this hypothesis. What emerges from these studies is a complex picture, where data have been obtained in support of this hypothesis, but there are also many circumstances where it is not supported. Taken together, these data suggest that the relationship between p53 and multidrug transporters is conditional. It is dependent on cellular environment, the drug used, and the nature of the p53 mutation.

ABC drug transporters: hereditary polymorphisms and pharmacological impact in MDR1, MRP1 and MRP2

Transport by ATP-dependent efflux pumps, such as P-glycoprotein (PGP) and multi-drug resistance related proteins (MRPs), influences bioavailability and disposition of drugs. These efflux pumps serve as defence mechanisms and determine bioavailability and CNS concentrations of many drugs. However, despite the fact that substantial data have been accumulated on the structure, function and pharmacological role of ABC transporters and even though modification of PGP function is an important mechanism of drug interactions and adverse effects in humans, there is a striking lack of data on variability of the underlying genes. This review focuses on the human drug transporter proteins PGP (MDR1) and the multi-drug resistance proteins MRP1 and MRP2. An overview is provided of pharmacologically relevant genetic, structural and functional data as well as on hereditary polymorphisms, their phenotypical consequences and pharmacological implications.

2-acetylaminofluorene up-regulates rat mdr1b expression through generating reactive oxygen species that activate NF-kappa B pathway

Overexpression of multidrug resistance genes and their encoded P-glycoproteins is a major mechanism for the development of multidrug resistance in cancer cells. The hepatocarcinogen 2-acetylaminofluorene (2-AAF) efficiently activates rat mdr1b expression. However, the underlying mechanisms are largely unknown. In this study, we demonstrated that a NF-kappa B site on the mdr1b promoter was required for this induction. Overexpression of antisense p65 and I kappa B alpha partially abolished the induction. We then delineated the pathway through which 2-AAF activates NF-kappa B. 2-AAF treatment led to the increase of intracellular reactive oxygen species (ROS) which causes activation of IKK kinases, degradation of I kappa B beta (but not I kappa B alpha), and increase in NF-kappa B DNA binding activity. Consistent with the idea that ROS may participate in mdr1b regulation, antioxidant N-acetylcysteine inhibited the induction of mdr1b by 2-AAF. Overproduction of a physiological antioxidant glutathione (GSH) blocked the activation of IKK kinase complex and NF-kappa B DNA binding. Based on these results, we conclude that 2-AAF up-regulates mdr1b through the generation of ROS, activation of IKK kinase, degradation of I kappa B beta, and subsequent activation of NF-kappa B. This is the first report that reveals the specific cis-elements and signaling pathway responsible for the induction of mdr1b by the chemical carcinogen 2-AAF.