Multidrug resistance (mdr) genes in human cancer

Biochemical, Toxicological, and in Silico Aspects of Trillium govanianum Wall. ex D.Don (Trilliaceae): A Rich Source of Natural Bioactive Compounds

Trillium govanianum is a high-value medicinal herb, having multifunctional traditional and culinary uses. The present investigation was carried out to evaluate the phytochemical, biological and toxicological parameters of the T. govanianum Wall. ex D. Don (Family: Trilliaceae) roots collected from Azad Kashmir, Pakistan. Phytochemical profiling was achieved by determining total bioactive contents (total phenolic and flavonoid contents) and UHPLC-MS analysis. For biological evaluation, antioxidant activities (DPPH, ABTS, FRAP, CUPRAC, phosphomolybdenum, and metal chelation assays) and enzyme inhibition activities (against AChE, BChE, glucosidase, amylase, and tyrosinase) were performed. Moreover, cytotoxicity was assessed against three human carcinoma cell lines (MDA-MB-231, CaSki, and DU-145). The tested extract was found to contain higher total phenolics (7.56 mg GAE/g dry extract) as compared to flavonoid contents (0.45 mg RE/g dry extract). Likewise, for the antioxidant activity, higher CUPRAC activity was noted with 39.84 mg TE/g dry extract values. In the case of enzyme assays, higher activity was pointed out against the cholinesterase, glucosidase and tyrosinase enzymes. The plant extract displayed significant cytotoxicity against the cell lines examined. Moreover, the in-silico studies highlighted the interaction between the important phytochemicals and tested enzymes. To conclude, the assessed biological activity and the existence of bioactive phytochemicals in the studied plant extract may pave the way for the development of novel pharmaceuticals.

P-Glycoprotein Activity at Diagnosis Does Not Predict Therapy Outcome and Survival in Canine B-Cell Lymphoma

Simple Summary

Clinical experience in human and canine clinics shows that following initial response to treatment, drug-resistant cancer cells frequently evolve and eventually, most tumors become resistant to all available therapies. The most straightforward cause of therapy resistance is linked to cellular alterations that prevent drugs from acting on their target. Drug efflux mediated by the ABC transporter P-glycoprotein (P-gp) contributes to unfavorable treatment outcome in several human malignancies. Here, we characterize a large cohort of canine B-cell lymphoma patients followed for over 7 years. We show that the intrinsic P-gp activity of tumor cells characterized at the time of diagnosis is not predictive for therapy outcome. Our results highlight the complexity of clinical drug resistance mechanisms and suggests that the relevance of P-gp in acquired resistance should be further investigated by the continuous monitoring of tumor cells during treatment.

Abstract

Various mechanisms are known to be involved in the development of multidrug resistance during cancer treatment. P-glycoprotein (P-gp) decreases the intracellular concentrations of cytotoxic drugs by an energy-dependent efflux mechanism. The aim of this study was to investigate the predictive value of P-gp function based on the evaluation of P-gp activity in tumor cells obtained from canine B-cell lymphoma patients at diagnosis. P-gp function of 79 immunophenotyped canine lymphoma samples was determined by flow cytometry using the Calcein assay. Dogs were treated with either the CHOP or the L-CHOP protocol, a subset of relapsed patients received L-asparaginase and lomustine rescue treatments. Among the 79 dogs, the median overall survival time was 417 days, and the median relapse-free period was 301 days. 47 percent of the samples showed high P-gp activity, which was significantly higher in Stage IV cancer patients compared to Stage II + III and V. Whereas staging was associated with major differences in survival times, we found that the intrinsic P-gp activity of tumor cells measured at diagnosis is not predictive for therapy outcome. Further studies are needed to identify the intrinsic and acquired resistant mechanisms that shape therapy response and survival in B-cell canine lymphoma patients.

Multidrug Resistance in Cancer: Understanding Molecular Mechanisms, Immunoprevention and Therapeutic Approaches

Cancer is one of the leading causes of death worldwide. Several treatments are available for cancer treatment, but many treatment methods are ineffective against multidrug-resistant cancer. Multidrug resistance (MDR) represents a major obstacle to effective therapeutic interventions against cancer. This review describes the known MDR mechanisms in cancer cells and discusses ongoing laboratory approaches and novel therapeutic strategies that aim to inhibit, circumvent, or reverse MDR development in various cancer types. In this review, we discuss both intrinsic and acquired drug resistance, in addition to highlighting hypoxia- and autophagy-mediated drug resistance mechanisms. Several factors, including individual genetic differences, such as mutations, altered epigenetics, enhanced drug efflux, cell death inhibition, and various other molecular and cellular mechanisms, are responsible for the development of resistance against anticancer agents. Drug resistance can also depend on cellular autophagic and hypoxic status. The expression of drug-resistant genes and the regulatory mechanisms that determine drug resistance are also discussed. Methods to circumvent MDR, including immunoprevention, the use of microparticles and nanomedicine might result in better strategies for fighting cancer.

Physiological Roles of ERM Proteins and Transcriptional Regulators in Supporting Membrane Expression of Efflux Transporters as Factors of Drug Resistance in Cancer

One factor contributing to the malignancy of cancer cells is the acquisition of drug resistance during chemotherapy via increased expression of efflux transporters, such as P-glycoprotein (P-gp), multidrug resistance-associated proteins (MRPs), and breast cancer resistance protein (BCRP). These transporters operate at the cell membrane, and are anchored in place by the scaffold proteins ezrin (Ezr), radixin (Rdx), and moesin (Msn) (ERM proteins), which regulate their functional activity. The identity of the regulatory scaffold protein(s) differs depending upon the transporter, and also upon the tissue in which it is expressed, even for the same transporter. Another factor contributing to malignancy is metastatic ability. Epithelial-mesenchymal transition (EMT) is the first step in the conversion of primary epithelial cells into mesenchymal cells that can be transported to other organs via the blood. The SNAI family of transcriptional regulators triggers EMT, and SNAI expression is used is an indicator of malignancy. Furthermore, EMT has been suggested to be involved in drug resistance, since drug excretion from cancer cells is promoted during EMT. We showed recently that ERM proteins are induced by a member of the SNAI family, Snail. Here, we first review recent progress in research on the relationship between efflux transporters and scaffold proteins, including the question of tissue specificity. In the second part, we review the relationship between ERM scaffold proteins and the transcriptional regulatory factors that induce their expression.

The Evolution and Ecology of Resistance in Cancer Therapy

Despite the continuous deployment of new treatment strategies and agents over many decades, most disseminated cancers remain fatal. Cancer cells, through their access to the vast information of the human genome, have a remarkable capacity to deploy adaptive strategies for even the most effective treatments. We note there are two critical steps in the clinical manifestation of treatment resistance. The first, which is widely investigated, requires molecular machinery necessary to eliminate the cytotoxic effect of the treatment. However, the emergence of a resistant phenotype is not in itself clinically significant. That is, resistant cells affect patient outcomes only when they succeed in the second step of resistance by proliferating into a sufficiently large population to allow tumor progression and treatment failure. Importantly, proliferation of the resistant phenotype is by no means certain and, in fact, depends on complex Darwinian dynamics governed by the costs and benefits of the resistance mechanisms in the context of the local environment and competing populations. Attempts to target the molecular machinery of resistance have had little clinical success largely because of the diversity within the human genome-therapeutic interruption of one mechanism simply results in its replacement by an alternative. Here we explore evolutionarily informed strategies (adaptive, double-bind, and extinction therapies) for overcoming treatment resistance that seek to understand and exploit the critical evolutionary dynamics that govern proliferation of the resistant phenotypes. In general, this approach has demonstrated that, while emergence of resistance mechanisms in cancer cells to every current therapy is inevitable, proliferation of the resistant phenotypes is not and can be delayed and even prevented with sufficient understanding of the underlying eco-evolutionary dynamics.

Stem Cell Therapy for Hepatocellular Carcinoma: Future Perspectives

Hepatocellular carcinoma (HCC) is one of the most common types of cancer and results in a high mortality rate worldwide. Unfortunately, most cases of HCC are diagnosed in an advanced stage, resulting in a poor prognosis and ineffective treatment. HCC is often resistant to both radiotherapy and chemotherapy, resulting in a high recurrence rate. Although the use of stem cells is evolving into a potentially effective approach for the treatment of cancer, few studies on stem cell therapy in HCC have been published. The administration of stem cells from bone marrow, adipose tissue, the amnion, and the umbilical cord to experimental animal models of HCC has not yielded consistent responses. However, it is possible to induce the apoptosis of cancer cells, repress angiogenesis, and cause tumor regression by administration of genetically modified stem cells. New alternative approaches to cancer therapy, such as the use of stem cell derivatives, exosomes or stem cell extracts, have been proposed. In this review, we highlight these experimental approaches for the use of stem cells as a vehicle for local drug delivery.

MicroRNA-mediated suppression of P-glycoprotein by quantum dots in lung cancer cells

The interactions between adenosine triphosphate-binding cassette (ABC) transporters and nano-sized materials are attracting increasing attention, due to their great potential in overcoming the multidrug resistance (MDR) phenomena in cancer treatment. However, the inner mechanisms involved in the interactions are largely unknown. In this study, two commercial quantum dots (QDs), CdSe/ZnS-MPA and CdSe/ZnS-GSH, were tested for their interactions with P-glycoprotein (P-gp), as well as the relating mechanisms in lung cancer (A549) cells. Both QDs significantly suppressed the gene and protein expressions of P-gp in A549 cells. To explain this, the gene expressions of nine relating microRNAs (miRNAs) were evaluated. The results indicated a shared up-regulation of miR-34b and miR-185 by both QDs. Furthermore, mimics and inhibitors of miR-34b and miR-185 significantly enhanced and suppressed the gene and protein expressions of P-gp, respectively, confirming the modulatory function of these two miRNAs on P-gp. Interestingly, expressions of both miRNAs were suppressed during treatment with Cd²⁺ and doxorubicin, which induced the expression of P-gp, indicating the universality of these miRNAs-related mechanisms. Thus, as miR-34b and miR-185 participated in the suppression of P-gp functions in A549 cells they could be interesting targets for the treatment of lung cancer.

Antiproliferative, neurotoxic, genotoxic and mutagenic effects of toxic cyanobacterial extracts

Cyanobacteria are the rich resource of various secondary metabolites including toxins with broad pharmaceutical significance. The aim of this work was to evaluate the antiproliferative, neurotoxic, genotoxic and mutagenic effects of cyanobacterial extracts containing Microcystin-LR (MCLR) in vitro. ELISA analysis results showed that MCLR contents of five cyanobacterial extracts were 2.07 ng/mL, 1.43 ng/mL, 1.41 ng/mL, 1.27 ng/mL, and 1.12 ng/mL for Leptolyngbya sp. SB1, Phormidium sp. SB4, Oscillatoria earlei SB5, Phormidium sp. SB2, Uncultured cyanobacterium, respectively. Phormidium sp. SB4 and Phormidium sp. SB2 extracts had the lowest neurotoxicity (86% and 79% cell viability, respectively) and Oscillatoria earlei SB5 extracts had the highest neurotoxicity (47% cell viability) on PC12 cell at 1000 µg/ml extract concentration. Leptolyngbya sp. SB1 and Phormidium sp. SB2 showed the highest antiproliferative effect (92% and 77% cell death) on HT29 cell. On the other hand, all concentrations of five toxic cyanobacterial extracts induced DNA damage between 3.0% and 1.3% of tail intensity and did not cause any direct mutagenic effect at the 1000 µg/plate cyanobacterial extracts. These results suggest that cyanobacteria-derived MCLR is a promising candidate for development of effective agents against colon cancer.

Anticancer and antibacterial effects of a clove bud essential oil-based nanoscale emulsion system

BACKGROUND AND PURPOSE

The essential oil derived from clove buds (Syzygium aromaticum) has been used as a chemopreventive agent in Ayurvedic medicine. The antiviral, antibacterial, and anticancer properties of its chemo-skeleton have motivated this study to explore its efficacy in pharmaceutics.

METHODS

Nanoscale-based emulsions were prepared by employing a spontaneous emulsification technique through self-assembly using varying concentrations of Tween 20 and Tween 80 surfactants. Their physicochemical properties and stability were studied in order to choose an optimum formulation which was clear and stable. The cytotoxicity of the stable oil-based emulsion system was evaluated using MTT assay, colony formation assay, and Annexin V-FITC assay against the thyroid cancer cell line (HTh-7).

RESULTS

All three methods verified apoptosis and reduction in cancer cell proliferation, making the formulation a promising candidate as an alternative cancer drug. The oil-based emulsion system was also tested for its antibacterial properties against Staphylococcus aureus. Membrane permeability studies proved its efficacy to permeate through cell membrane, thereby increasing the leakage of cytoplasmic contents.

CONCLUSION

Many current treatments for cancers are aggressive yet ineffective. This study positions the clove bud-based nanoscale emulsion as a suitable candidate for further in vivo studies and trials as a cancer drug.

siRNA-Conjugated Nanoparticles to Treat Ovarian Cancer

Ovarian cancer is the fifth-most lethal cancer among women due to a lack of early detection and late-stage treatment options, and it is responsible for more than 14,000 deaths each year in the United States. Recently, there have been advances in RNA interference therapy, specifically with small interfering RNA (siRNA), to reduce tumor burden for ovarian cancer via gene down-regulation. However, delivery of siRNA poses its own challenges, as siRNA is unstable in circulation, is unable to be effectively internalized by cells, and may cause toxicity in off-target sites. To address such challenges, nanoparticle carriers have emerged as delivery platforms for the biocompatible, targeted delivery of siRNA-based therapies. Several preclinical studies have shown the promising effects of siRNA therapy to reduce chemotherapy resistance and proliferation of ovarian cancer cells. This review evaluates the recent advances, clinical applications, and future potential of nanoparticle-mediated delivery of siRNA therapeutics to target genes implicated in ovarian cancer.

Chondrosarcoma: An overview of clinical behavior, molecular mechanisms mediated drug resistance and potential therapeutic targets

Sarcomas are known as a heterogeneous class of cancers arisen in the connective tissues and demonstrated various histological subtypes including both soft tissue and bone origin. Chondrosarcoma is one of the main types of bone sarcoma that shows a considerable deficiency in response to chemotherapy and radiotherapy. While conventional treatment based on surgery, chemo-and radiotherapy are used in this tumor, high rate of death especially among children and adolescents are reported. Due to high resistance to current conventional therapies in chondrosarcoma, there is an urgent requirement to recognize factors causing resistance and discover new strategies for optimal treatment. In the past decade, dysregulation of genes associated with tumor development and therapy resistance has been studied to find potential therapeutic targets to overcome resistance. In this review, clinical aspects of chondrosarcoma are summarized. Moreover, it gives a summary of gene dysregulation, mutation, histone modifications and non-coding RNAs associated with tumor development and therapeutic response modulation. Finally, the probable role of tumor microenvironment in chondrosarcoma drug resistance and targeted therapies as a promising molecular therapeutic approach are summarized.

ABCB1 and ABCC1-like transporters in immune system cells from sea urchins Echinometra lucunter and Echinus esculentus and oysters Crassostrea gasar and Crassostrea gigas

ABC transporters activity and expression have been associated with the multixenobiotic resistance phenotype (MXR). The activity of these proteins leads to a reduction in the intracellular concentration of several xenobiotics, thus reducing their toxicity. However, little attention has been given to the expression of ABC transporters in marine invertebrates and few studies have investigated their role in immune system cells of sea urchins and shellfish bivalves. The aim of the present study was to investigate the activity of the ABC transporters ABCB1 and ABCC1 in immune system cells of sea urchins (coelomocytes) and oysters (hemocytes) from different climatic regions (Brazil and France). Sea urchins and oysters were collected at Paraíba coast; Brazil (Echinometra lucunter and Crassostrea gasar) and Rade of Brest; France (Echinus esculentus and Crassostrea gigas). Coelomocytes and hemocytes were stained with the ABC transporter substrate calcein-AM and dye accumulation analyzed under flow cytometry. Reversin 205 (ABCB1 transporter blocker) and MK571 (ABCC1 transporter blocker) were used as pharmacological tools to investigate ABC transporter activity. A different pattern of calcein accumulation was observed in coelomocytes: phagocytes > colorless spherulocytes > vibrate cells > red spherulocytes. The treatment with MK571 increased calcein fluorescence levels in coelomocytes from both species. However, reversin 205 treatment was not able to increase calcein fluorescence in E. esculentus coelomocytes. These data suggest that ABCC1-like transporter activity is present in both sea urchin species, but ABCB1-like transporter activity might only be present in E. lucunter coelomocytes. The activity of ABCC1-like transporter was observed in all cell types from both bivalve species. However, reversin 205 only increased calcein accumulation in hyalinocytes of the oyster C. gasar, suggesting the absence of ABCB1-like transporter activity in all other cell types, including hyalinocytes from the oyster C. gigas. Additionally, our results showed that C. gigas exhibited higher activity of ABCC1-like transporter in all hemocyte types than C. gasar. The present work is the first to characterize ABCB1 and ABCC1-like transporter activity in the immune system cells of sea urchins E. lucunter and E. esculentus and oysters. Our findings encourage the performing studies regarding ABC transporters activity/expression in immune system cells form marine invertebrates under stress conditions and the possible use of ABC transporters as biomarkers.

Pilot study: duodenal MDR1 and COX2 gene expression in cats with inflammatory bowel disease and low-grade alimentary lymphoma

Objectives Multidrug resistance 1 (MDR1) encodes a protein called P-glycoprotein (P-gp), which serves as an efflux pump membrane protein implicated in intestinal homeostasis and drug resistance. Cyclooxygenase-2 (COX2) is a key enzyme in the synthesis of proinflammatory prostaglandins, tumourigenesis and in mucosal defence. Despite the importance of MDR1 and COX2, changes in their mRNA levels have not been studied in cats with inflammatory bowel disease (IBD) and low-grade alimentary lymphoma (LGAL). The present study aimed to determine the mRNA levels of MDR1 and COX2 in cats with IBD and LGAL, and to evaluate their correlation with clinical signs, histological severity and between genes. Methods Cats diagnosed with IBD (n = 20) and LGAL (n = 9) between 2008 and 2015 were included in the current study. Three healthy animals composed the healthy control cats group in which endoscopy was performed immediately before the ovariohysterectomy. All duodenal biopsy samples were obtained by endoscopy. Feline chronic enteropathy activity index was calculated for all cases. IBD histopathology was classified according to severity. MDR1 and COX2 mRNA levels were determined by absolute reverse transcriptase-quantitative real-time PCR. Results Statistically significant differences were observed for MDR1 and COX2 mRNA levels between the IBD and LGAL groups. No correlations were observed between molecular gene expression, feline chronic enteropathy activity index and histological grading for IBD, and between MDR1 and COX2 genes. However, a positive statistically significant correlation was observed between MDR1 and COX2 expression in the duodenum of cats. Conclusions and relevance MDR1 and COX2 gene expression is increased in cats with LGAL compared with cats with IBD. The control group tended to have lower values than both diseased groups. These results suggest that these genes may be involved in the pathogenesis of IBD or LGAL in cats.

Thiopurine use associated with reduced B and natural killer cells in inflammatory bowel disease

AIM

To identify which blood and mucosal lymphocyte populations are specifically depleted by thiopurine use in vivo.

METHODS

The thiopurines azathioprine and 6-mercaptopurine have been a mainstay of inflammatory bowel disease (IBD) therapy for decades, but their mechanism of action in vivo remains obscure. Although thiopurines are lymphotoxic at high doses, and have been reported to cause T cell apoptosis in vitro, their ability to control IBD at lower doses suggests that they may selectively deplete particular lymphocyte populations. Blood cells from 19 IBD patients on a thiopurine, 19 IBD patients not on a thiopurine, and 38 matched healthy control subjects were analyzed by multiple multi-color flow cytometry panels to quantify the immune cell subsets contained therein, both as a percent of cells, and as an absolute cell count. Similar analyses were performed on colon biopsies from 17 IBD patients on a thiopurine, 17 IBD patients not on a thiopurine, and 49 healthy screening colonoscopy recipients.

RESULTS

Complete blood counts revealed lower lymphocyte, but not monocyte or granulocyte, counts in IBD patients who were taking thiopurines at the time of sampling. This reduction was restricted to CD3-negative lymphocytes, wherein both natural killer (NK) and B cells were significantly reduced among thiopurine recipients. Among CD19+ B cells, the transitional B cells were particularly depleted, being nearly absent in both blood and colon biopsies of thiopurine recipients. No differences were associated with thiopurine use in CD8+ T cells, mucosa-associated invariant T (MAIT) cells, invariant natural killer T (iNKT) cells, gamma/delta T cells, Th1, Th17, regulatory T cells (Tregs) or naïve CD4+ T cells. However, patients with IBD had significantly more circulating FOXP3+, Helios+ Tregs and fewer iNKT and MAIT cells than healthy controls.

CONCLUSION

Thiopurine use is associated with reduced B and NK cell, but not T cell, subpopulations in the blood of IBD patients.

Effectiveness of imatinib mesylate over etoposide in the treatment of sensitive and resistant chronic myeloid leukaemia cells in vitro

Chronic myeloid leukaemia (CML) is a form of leukaemia derived from the myeloid cell lineage. Imatinib mesylate, the breakpoint cluster region-abelson murine leukeamia kinase inhibitor, is a specific reagent used in the clinical treatment of CML. The DNA topoisomerase II inhibitor, etoposide, is also employed as a therapeutic, though it is used to a lesser extent. The present study aims to evaluate the effects of CML-targeted therapy, utilising imatinib mesylate and etoposide in the in vitro treatment of parental sensitive and adriamycin-resistant CML in the K562 and K562/ADM cell lines, respectively. Preliminary work involved the screening of multidrug resistant (MDR) gene expression, including MDR1, MRP1 and B-cell lymphoma 2 (BCL-2) at the mRNA levels. The sensitive and resistant CML cell lines expressed the MRP1 gene, though the sensitive K562 cells expressed low, almost undetectable levels of MDR1 and BCL-2 genes relative to the K562/ADM cells. Following treatment with imatinib mesylate or etoposide, the IC50 for imatinib mesylate did not differ between the sensitive and resistant cell lines (0.492±0.024 and 0.378±0.029, respectively), indicating that imatinib mesylate is effective in the treatment of CML regardless of cell chemosensitivity. However, the IC50 for etoposide in sensitive K562 cells was markedly lower than that of K562/ADM cells (50.6±16.5 and 194±8.46 µM, respectively), suggesting that the higher expression levels of MDR1 and/or BCL-2 mRNA in resistant cells may be partially responsible for this effect. This is supported by terminal deoxynucleotidyl transferase dUTP nick-end labeling data, whereby a higher percentage of apoptotic cells were found in the sensitive and resistant K562 cells treated with imatinib mesylate (29.3±0.2 and 31.9±16.7%, respectively), whereas etoposide caused significant apoptosis of sensitive K562 cells (18.3±8.35%) relative to K562/ADM cells (5.17±3.3%). In addition, the MDR genes in K562/ADM cells were knocked down by short interfering RNAs. The percentage knockdowns were 15.4% for MRP1, 17.8% for MDR and 30.7% for BCL-2, which resulted in a non-significant difference in the half maximal inhibitory concentration value of K562/ADM cells relative to K562 cells upon treatment with etoposide.

Highly Expressed Integrin-α8 Induces Epithelial to Mesenchymal Transition-Like Features in Multiple Myeloma with Early Relapse

Despite recent groundbreaking advances in multiple myeloma (MM) treatment, most MM patients ultimately experience relapse, and the relapse biology is not entirely understood. To define altered gene expression in MM relapse, gene expression profiles were examined and compared among 16 MM patients grouped by 12 months progression-free survival (PFS) after autologous stem cell transplantation. To maximize the difference between prognostic groups, patients at each end of the PFS spectrum (the four with the shortest PFS and four with the longest PFS) were chosen for additional analyses. We discovered that integrin-α8 (ITGA8) is highly expressed in MM patients with early relapse. The integrin family is well known to be involved in MM progression; however, the role of integrin-α8 is largely unknown. We functionally overexpressed integrin-α8 in MM cell lines, and surprisingly, stemness features including HIF1α, VEGF, OCT4, and Nanog, as well as epithelial mesenchymal transition (EMT)-related phenotypes, including N-cadherin, Slug, Snail and CXCR4, were induced. These, consequently, enhanced migration and invasion abilities, which are crucial to MM pathogenesis. Moreover, the gain of integrin-α8 expression mediated drug resistance against melphalan and bortezomib, which are the main therapeutic agents in MM. The cBioPortal genomic database revealed that ITGA8 have significant tendency to co-occur with PDGFRA and PDGFRB and their mRNA expression were up-regulated in ITGA8 overexpressed MM cells. In summary, integrin-α8, which was up-regulated in MM of early relapse, mediates EMT-like phenotype, enhancing migration and invasion; therefore, it could serve as a potential marker of MM relapse and be a new therapeutic target.

Immunohistochemical detection of P-glycoprotein in various subtypes of canine lymphomas

Combination chemiotherapy is the current standard of care for dogs with lymphoma. Multidrug resistance is one of the most important factors contributing to the efficacy of chemiotherapy. The major protein responsible for this phenomenon is P-glycoprotein. Little is known about P-glycoprotein expression in particular subtypes of lymphomas. The aim of the study was evaluation of P-glycoprotein expression in various subtypes of canine lymphomas. Positive reaction with P-glycoprotein was found in 12/25 cases of various morphological subtypes of lymphomas, however, in 3/11 lymphomas the percentage of positively weakly stained cells was < 10% and those tumors were also considered negative. Tumors with 10-50% P-glycoprotein positive cells were found in single cases of centroblastic and centroblastic-centrocytic tumors. In 5 lymphomas P-glycoprotein expression exceeded 50% of tumor cells. Those cases were found among centroblastic, centroblastic-centrocytic, lymphoblastic and Burkitt-like subtypes. Positive reaction was observed mainly in the cell cytoplasm, however, in some cases prominent perinuclear dot-like staining pattern was found. In 2 cases focal staining pattern comprised dominant type of immunolabelling. Among all lymphomas containing P-glycoprotein positive cells intensity of imunolabelling was assessed as weak (6/25), moderate (2/25) and strong (3/25). Our results indicate that P-glycoprotein expression is present in nearly one third of newly diagnosed canine lymphomas of different morphological subtypes including those most commonly occurring, such as cenroblastic lymphomas. Hence, determination of P-glycoprotein expression at the time of diagnosis could provide valuable information for the design of treatment protocols. Moreover, our results have shown that P-glycoprotein expression in canine tumors could be located in Golgi-zone.

A robust and versatile signal-on fluorescence sensing strategy based on SYBR Green I dye and graphene oxide

A robust and versatile signal-on fluorescence sensing strategy was developed to provide label-free detection of various target analytes. The strategy used SYBR Green I dye and graphene oxide as signal reporter and signal-to-background ratio enhancer, respectively. Multidrug resistance protein 1 (MDR1) gene and mercury ion (Hg(2+)) were selected as target analytes to investigate the generality of the method. The linear relationship and specificity of the detections showed that the sensitive and selective analyses of target analytes could be achieved by the proposed strategy with low detection limits of 0.5 and 2.2 nM for MDR1 gene and Hg(2+), respectively. Moreover, the strategy was used to detect real samples. Analytical results of MDR1 gene in the serum indicated that the developed method is a promising alternative approach for real applications in complex systems. Furthermore, the recovery of the proposed method for Hg(2+) detection was acceptable. Thus, the developed label-free signal-on fluorescence sensing strategy exhibited excellent universality, sensitivity, and handling convenience.

Paris saponin VII from trillium tschonoskii reverses multidrug resistance of adriamycin-resistant MCF-7/ADR cells via P-glycoprotein inhibition and apoptosis augmentation

ETHNOPHARMACOLOGICAL RELEVANCE

Saponins of several herbs are known to induce apoptosis in some cancer cells and are proposed to be promising modulators of drug resistance. In the present study, we extracted Paris saponin VII (PS VII), a kind of saponin, from Trillium tschonoskii Maxim. and observed its effect on adriamycin-resistant breast cancer cells.

MATERIALS AND METHODS

An adriamycin-resistant human breast cancer cell line, MCF-7/ADR cells were exposed to different concentrations of PS VII (0-100 μmol/L). Then, flow cytometric assays and a human apoptosis array were used to detect apoptotic cells and apoptosis related protein expression. P-glycoprotein levels and intracellular rhodamine 123 (RH-123) accumulations were measured to evaluate the expression and activity of P-glycoprotein.

RESULTS

PS VII dose dependently suppressed cell viability as well as triggered apoptosis and modulated drug resistance of MCF-7/ADR cells. Further results showed that PS VII treatment in MCF-7/ADR cells led to increased TNFR1, TRAIL R1/DR4, TRAIL R2/DR5, and FADD expression, and activation of PARP, caspase-8, and 3. In parallel to the alterations, P-glycoprotein expression and activity were also reduced.

CONCLUSION

These findings showed that PS VII might be an effective tumouristatic agent for the treatment of MDR breast cancer.

Essential oils and their constituents as anticancer agents: a mechanistic view

Exploring natural plant products as an option to find new chemical entities as anticancer agents is one of the fastest growing areas of research. Recently, in the last decade, essential oils (EOs) have been under study for their use in cancer therapy and the present review is an attempt to collect and document the available studies indicating EOs and their constituents as anticancer agents. This review enlists nearly 130 studies of EOs from various plant species and their constituents that have been studied so far for their anticancer potential and these studies have been classified as in vitro and in vivo studies for EOs and their constituents. This review also highlights in-depth various mechanisms of action of different EOs and their constituents reported in the treatment strategies for different types of cancer. The current review indicates that EOs and their constituents act by multiple pathways and mechanisms involving apoptosis, cell cycle arrest, antimetastatic and antiangiogenic, increased levels of reactive oxygen and nitrogen species (ROS/RNS), DNA repair modulation, and others to demonstrate their antiproliferative activity in the cancer cell. The effect of EOs and their constituents on tumour suppressor proteins (p53 and Akt), transcription factors (NF- κB and AP-1), MAPK-pathway, and detoxification enzymes like SOD, catalase, glutathione peroxidase, and glutathione reductase has also been discussed.

Endogenous Voltage Potentials and the Microenvironment: Bioelectric Signals that Reveal, Induce and Normalize Cancer

Cancer may be a disease of geometry: a misregulation of the field of information that orchestrates individual cells' activities towards normal anatomy. Recent work identified molecular mechanisms underlying a novel system of developmental control: bioelectric gradients. Endogenous spatio-temporal differences in resting potential of non-neural cells provide instructive cues for cell regulation and complex patterning during embryogenesis and regeneration. It is now appreciated that these cues are an important layer of the dysregulation of cell: cell interactions that leads to cancer. Abnormal depolarization of resting potential (Vmem) is a convenient marker for neoplasia and activates a metastatic phenotype in genetically-normal cells in vivo. Moreover, oncogene expression depolarizes cells that form tumor-like structures, but is unable to form tumors if this depolarization is artificially prevented by misexpression of hyperpolarizing ion channels. Vmem triggers metastatic behaviors at considerable distance, mediated by transcriptional and epigenetic effects of electrically-modulated flows of serotonin and butyrate. While in vivo data on voltages in carcinogenesis comes mainly from the amphibian model, unbiased genetic screens and network profiling in rodents and human tissues reveal several ion channel proteins as bona fide oncogene and promising targets for cancer drug development. However, we propose that a focus on specific channel genes is just the tip of the iceberg. Bioelectric state is determined by post-translational gating of ion channels, not only from genetically-specified complements of ion translocators. A better model is a statistical dynamics view of spatial Vmem gradients. Cancer may not originate at the single cell level, since gap junctional coupling results in multi-cellular physiological networks with multiple stable attractors in bioelectrical state space. New medical applications await a detailed understanding of the mechanisms by which organ target morphology stored in real-time patterns of ion flows is perceived or mis-perceived by cells. Mastery of somatic voltage gradients will lead to cancer normalization or rebooting strategies, such as those that occur in regenerating and embryonic organs, resulting in transformative advances in basic biology and oncology.

Correlation between PgP, TP, GST-π and MRP expression and response to chemotherapy in patients with esophageal cancer

AIM: To study the relationship between expression of P-glycoprotein (PgP), thymidine phosphorylase (TP), glutathione S-transferase-π (GST-π), and multidrug resistance-associated protein (MRP) and response to chemotherapy in patients with esophageal cancer.

METHODS: Fifty-eight patients gastroscopically and pathologically diagnosed with esophageal cancer were included in this study. Esophageal cancer samples collected from these patients were used to detect the expression of PgP, TP, GST-π, and MRP by immunohistochemistry. All the patients underwent neoadjuvant chemotherapy with double-platinum regimen. Response to chemotherapy and expression of PgP, TP, GST-π, and MRP was analyzed.

RESULTS: PgP-positive particles were distributed in the membrane and cytoplasm, TP-positive particles in the cytoplasm and nucleus, GST-π-positive particles in the cytoplasm, and MRP-positive particles in the cytoplasm. The positive rates of PgP, TP, GST-π, and MRP expression in esophageal cancer were 41.37%, 32.76%, 20.69% and 37.93%, respectively. Compared to patients not responding to chemotherapy, the positive rates of PgP, GSH and MRP expression were significantly lower and that of TP was significantly higher in patients having response to chemotherapy.

CONCLUSION: Low expression of PgP, GST-π, and MRP and high expression of TP are conducive to chemotherapy in patients with esophageal cancer.

Morphogenetic fields in embryogenesis, regeneration, and cancer: non-local control of complex patterning

Establishment of shape during embryonic development, and the maintenance of shape against injury or tumorigenesis, requires constant coordination of cell behaviors toward the patterning needs of the host organism. Molecular cell biology and genetics have made great strides in understanding the mechanisms that regulate cell function. However, generalized rational control of shape is still largely beyond our current capabilities. Significant instructive signals function at long range to provide positional information and other cues to regulate organism-wide systems properties like anatomical polarity and size control. Is complex morphogenesis best understood as the emergent property of local cell interactions, or as the outcome of a computational process that is guided by a physically encoded map or template of the final goal state? Here I review recent data and molecular mechanisms relevant to morphogenetic fields: large-scale systems of physical properties that have been proposed to store patterning information during embryogenesis, regenerative repair, and cancer suppression that ultimately controls anatomy. Placing special emphasis on the role of endogenous bioelectric signals as an important component of the morphogenetic field, I speculate on novel approaches for the computational modeling and control of these fields with applications to synthetic biology, regenerative medicine, and evolutionary developmental biology.

Multidrug Resistance (MDR) Gene Expression in Acute Non Lymphoblastic Leukemia: Sequential Analysis

Sequential evaluation of P-glycoprotein expression was performed in 29 patients with acute nonlymphoblastic leukemia using immunocytochemistry with the C219 antibody. At diagnosis, 32% of the patients exhibited more than 5% of the P-gp(+) leukemic cells. Under chemotherapy, 62% of the patients eventually expressed a subset of P-gp positive leukemic cells. After conventional doses of cytosine-arabinoside (Ara-C) and daunorubicin or mitoxantrone, positive P-gp cells were noted in 65% of the cases. This percentage was significantly higher (p = 0.002) than the proportion of positive cases (15%) observed after regimens containing either intermediate doses of Ara-C or cyclosporine A, a P-gp modulator.

Systems biology of the cell cycle of Saccharomyces cerevisiae: From network mining to system-level properties

Following a brief description of the operational procedures of systems biology (SB), the cell cycle of budding yeast is discussed as a successful example of a top-down SB analysis. After the reconstruction of the steps that have led to the identification of a sizer plus timer network in the G1 to S transition, it is shown that basic functions of the cell cycle (the setting of the critical cell size and the accuracy of DNA replication) are system-level properties, detected only by integrating molecular analysis with modelling and simulation of their underlying networks. A detailed network structure of a second relevant regulatory step of the cell cycle, the exit from mitosis, derived from extensive data mining, is constructed and discussed. To reach a quantitative understanding of how nutrients control, through signalling, metabolism and transcription, cell growth and cycle is a very relevant aim of SB. Since we know that about 900 gene products are required for cell cycle execution and control in budding yeast, it is quite clear that a purely systematic approach would require too much time. Therefore lines for a modular SB approach, which prioritises molecular and computational investigations for faster cell cycle understanding, are proposed. The relevance of the insight coming from the cell cycle SB studies in developing a new framework for tackling very complex biological processes, such as cancer and aging, is discussed.

The effect of survivin on multidrug resistance mediated by P-glycoprotein in MCF-7 and its adriamycin resistant cells

Although anticancer chemotherapeutic drugs have been designed to inhibit the growth of tumor cells, chemotherapy frequently fails due to the development of multidrug resistance (MDR). In this paper, the effect of survivin on multidrug resistance mediated by P-glycoprotein (Pgp) was investigated in breast cancer cells. Overexpression of survivin in MCF-7 cells transfected with survivin expression vector pEGFP/survivin results in decreasing sensitivity to anticancer drugs and activation of Pgp to export drug out of cells. Down regulation of survivin in MCF-7/adriamycin (ADR) transfected with RNAi directed against survivin vector psh1/survivin could increase the drug accumulation in cells by inhibiting Pgp. Downregulation of the expression of the Pgp with the specific inhibitor verapamil could markedly suppress the survivin mRNA expression, whereas the reverse impact was not observed. Survivin might modulate the turnover of Pgp or transport by Pgp in cells, which result in anti-apoptosis and drug resistance. Our results suggest that survivin might play a key role in MDR in the presence of Pgp, and this might represent a novel strategy for modulating MDR in cancer cells.

Lipid rafts: dream or reality for cholesterol transporters?

As a key constituent of the cell membranes, cholesterol is an endogenous component of mammalian cells of primary importance, and is thus subjected to highly regulated homeostasis at the cellular level as well as at the level of the whole body. This regulation requires adapted mechanisms favoring the handling of cholesterol in aqueous compartments, as well as its transfer into or out of membranes, involving membrane proteins. A membrane exhibits functional properties largely depending on its lipid composition and on its structural organization, which very often involves cholesterol-rich microdomains. Then there is the appealing possibility that cholesterol may regulate its own transmembrane transport at a purely functional level, independently of any transcriptional regulation based on cholesterol-sensitive nuclear factors controling the expression level of lipid transport proteins. Indeed, the main cholesterol "transporters" presently believed to mediate for instance the intestinal absorption of cholesterol, that are SR-BI, NPC1L1, ABCA1, ABCG1, ABCG5/G8 and even P-glycoprotein, all present privileged functional relationships with membrane cholesterol-containing microdomains. In particular, they all more or less clearly induce membrane disorganization, supposed to facilitate cholesterol exchanges with the close aqueous medium. The actual lipid substrates handled by these transporters are not yet unambiguously determined, but they likely concern the components of membrane microdomains. Conversely, raft alterations may provide specific modulations of the transporter activities, as well as they can induce indirect effects via local perturbations of the membrane. Finally, these cholesterol transporters undergo regulated intracellular trafficking, with presumably some relationships to rafts which remain to be clarified.

The theory of biological robustness and its implication in cancer

One of the essential issues in systems biology is to identify fundamental principles that govern living organisms at the system level. In this chapter, I argue that robustness is a fundamental feature of living systems where its relationship with evolution-trade-offs among robustness, fragility, resource demands, and performance-provides a possible framework for how biological systems have evolved and been organized. In addition, diseases can be con- sidered as a manifestation of fragility of the system. In some cases, such as cancer, the disease state establishes its own robustness against therapeutic interventions. Understanding robustness and its intrinsic properties will provide us with a more profound understanding of biological systems, their anomalies, and countermeasures.

Tumor markers in ovarian carcinoma

This review analyzes in 2 ways the prognostic value of markers found in ovarian carcinomas before chemotherapy. It is known that neoangiogenesis, cyclooxygenase activity, and host responsiveness to chemotherapy can be evaluated by means of specific molecules recognized as tumor markers. However, host response as well as tumor histotype, grade of differentiation, clinical characteristics, and histopathologic characteristics must also be taken into account when selecting a treatment. Analysis must therefore focus on the molecular basis of aggressive disease, on tumor peculiarity, on the efficacy of chemotherapy, and on the host's response to the tumor. Although treatment may be more aggressive in patients with unfavorable prognostic elements, it may be modulated according to the molecular and cellular biology of the tumor and the host's response. When the tumor's molecular characterization contributes to the choice of treatment, prognostic markers may turn into predictive markers.

Sanguinarine overcomes P-glycoprotein-mediated multidrug-resistance via induction of apoptosis and oncosis in CEM-VLB 1000 cells

Permeability-glycoprotein (Pgp) positive cells are known to be encoded by the multidrug-resistance gene (MDR1), and characterized by a reduced ability to accumulate drugs. The vinblastin-resistant, Pgp positive CEM-VLB 1000 and its wild type (Pgp-negative and vinblastin-sensitive) counterpart CEM-T4 human leukemia cells, when treated with the alkaloid sanguinarine, were both found to undergo apoptosis at concentrations of 1.5 microg/ml and oncosis/blister cell death (BCD) at concentrations of 12.5 microg/ml. The aim of this study was to assess the ability of sanguinarine to overcome Pgp-mediated multidrug-resistance (MDR), and also to characterize the cell death processes of apoptosis and oncosis (or bimodal cell death) induced by sanguinarine in MDR cells. The cell death processes of apoptosis and oncosis in CEM-VLB 1000 and CEM-T4 cell lines were found to be qualitatively similar when assessed by light microscopy, terminal deoxynucleotidyl transferase (TdT) end-labeling, annexin-V-binding, trypan blue exclusion and western blot analysis. Western blotting revealed an increase in the Bax/Bcl-2 ratio and activation of caspase-3 in apoptosis but not oncosis in both cell lines. The Pgp-positive CEM-VLB 1000 cells and their wild type CEM-T4 cells were both equally sensitive to sanguinarine. Thus, sanguinarine may overcome the phenomenon of Pgp-mediated MDR by inducing apoptosis through increasing the Bax/Bcl-2 ratio and activating caspase-3, and oncosis, which involved neither.

RNA expression of MDR1/P-glycoprotein, DNA-topoisomerase I, and MRP2 in ovarian carcinoma patients: correlation with chemotherapeutic response

OBJECTIVE

Clinical drug resistance is the major obstacle in the successful treatment of ovarian cancer. Besides elevated expression of adenosine triphosphate binding cassette (ABC) transporters, such as MDR1/P-gp or MRP2/cMOAT/ABCC2, alterations in the expression of DNA topoisomerase I (TOP1) are associated with drug-resistant phenotypes in various model systems.

METHODS

In ovarian specimens of 61 patients, the mRNA expression levels of MDR1/P-gp, MRP2, and TOP1 were determined using a competitive quantitative RT-PCR protocol with internal standards. The mRNA expression levels were correlated with the clinical outcome and histopathological criteria. The tumor specimens included 11/61 (18%) benign ovarian tumors, including 2 LMP tumors, and 50/61 (82%) ovarian carcinomas, including 34 primary and 16 recurrent cancers. Moreover, 20/61 (33%) ovarian specimens showed low or no MDR1/P-gp expression.

RESULTS

None of the benign tumors showed MRP2 expression, whereas 15/50 (30%) ovarian carcinomas expressed MRP2. In 61/61 (100%) of the samples, expression of TOP1 could be measured. In patients with recurrent ovarian cancer, no differences in expression of any of the factors could be observed. In patients with primary FIGO III carcinomas (n = 18), the overall-survival time (OST) was significantly prolonged with low MDR1/P-gp expression level (P = 0.015). Expression levels of MRP2 and TOP1 did not correlate with OST. Moreover, the progression-free survival (PFS) in FIGO III patients showed a clear tendency to be associated with low MDR1/P-gp (P = 0.218) and TOP1 expression (P = 0.466), and negativity for MRP2 (P = 0.244).

CONCLUSION

MDR1/P-gp and MRP2 might have some additional predictive value for the clinical outcome of patients with advanced ovarian carcinoma.

A phase I and pharmacologic study of the MDR converter GF120918 in combination with doxorubicin in patients with advanced solid tumors

BACKGROUND

Resistance to chemotherapy can partly be explained by the activity of membrane bound P-glycoprotein. Competitive inhibition of P-glycoprotein, by multidrug resistance (MDR) converters, may overcome this MDR. Previously studied MDR converters either have serious intrinsic side effects or considerably influence the pharmacokinetics of cytotoxic agents at concentrations theoretically required to convert MDR. GF120918 is a third-generation MDR converter with high affinity for P-glycoprotein and can be given orally. We performed a phase 1 study with escalating doses of GF120918 in combination with doxorubicin.

PATIENTS AND METHODS

The study group comprised 46 patients with advanced solid tumors. Doxorubicin was administered on day 1 (cycle 1), GF120918 on days 22-24 (cycle 2), and on days 29-33 with doxorubicin administered on day 31 (cycle 3). Pharmacokinetics of both GF120918 and doxorubicin were studied. The starting daily dose of GF120918 was 50 mg and was to be increased in subsequent cohorts until a steady state plasma level of 100 ng/ml was reached. The starting dose of doxorubicin was 50 mg/m2 and was to be increased after reaching the target dose level of GF120918.

RESULTS

In 37 of the 46 patients, full pharmacokinetic data from the three scheduled cycles were obtained. Pharmacokinetics of GF120918 showed a less than linear increase in Cmax with increasing doses, with considerable interpatient variation. The target steady-state plasma level for GF120918 was exceeded in 12 out of 19 patients who received 400 mg GF120918 alone twice daily and in 12 of 17 patients who received 400 mg GF120918 twice daily in combination with doxorubicin. GF120918 pharmacokinetics were not influenced by coadministration of doxorubicin. The doxorubicin AUC was only marginally influenced by GF120918 and only at the highest dose levels. In these patients there was a significant increase in the AUC of doxorubicinol in cycle 3 as compared to cycle 1. Hematologic toxicity mainly consisted of neutropenia and was more severe in cycle 3 than in cycle 1 (13 vs 5 patients with grade 4 neutropenia, P=0.003). Neutropenic fever was the dose-limiting toxicity at a doxorubicin dose of 75 mg/m2 with 400 mg GF120918 twice daily. The toxicity of GF120918 was limited to somnolence in eight patients and occasional gastrointestinal complaints.

CONCLUSION

GF120918 is an MDR converter with only minimal side effects at a dose level yielding concentrations able to convert the action of P-glycoprotein in vitro. A doxorubicin dose of 60 mg/m2 on day 3 in combination with 400 mg GF120918 twice daily on days 1-5 is an acceptable regimen for further clinical trials.

Inhibition of tumor-associated fatty acid synthase hyperactivity induces synergistic chemosensitization of HER -2/ neu -overexpressing human breast cancer cells to docetaxel (taxotere)

The lipogenic enzyme fatty acid synthase (FAS) is differentially overexpressed and hyperactivated in a biologically aggressive subset of breast carcinomas and minimally in most normal adult tissues, rendering it an interesting target for antineoplastic therapy development. Recently, a molecular connection between the HER -2/ neu (c- erb B-2) oncogene and FAS has been described in human breast cancer cells. Here, we examined the relationship between breast cancer-associated FAS hyperactivity and HER -2/ neu -induced breast cancer chemoresistance to taxanes. Co-administration of docetaxel (Taxotere) and the mycotoxin cerulenin, a potent and non-competitive inhibitor of FAS activity, demonstrated strong synergism in HER -2/ neu -overexpressing and docetaxel-resistant SK-Br3 cells, modest synergism in moderately HER -2/ neu -expressing MCF-7 cells, and it showed additive effects in low HER -2/ neu -expressing and docetaxel-sensitive MDA-MB-231 cells. Sequential exposure to cerulenin followed by docetaxel again yielded strong synergism in SK-Br3 cells, whereas antagonistic and moderate synergistic interactions were observed in MCF-7 and MDA-MB-231 cells, respectively. Importantly, inhibition of FAS activity dramatically decreased the expression of HER -2/ neu oncogene in SK-Br3 breast cancer cells. To the best of our knowledge this is the first study demonstrating that FAS is playing an active role in HER -2/ neu -induced breast cancer chemotherapy resistance.

Immunotherapy for renal cell carcinoma

Renal cell carcinoma (RCC) is the most prevalent malignancy within the kidney and the incidence is rising. Due to improved radiological evaluation over 50% of the renal cancers are found incidentally. Despite the fact that these incidentalomas are often confined to the kidney, around 50% of all patients diagnosed with kidney cancer will develop systemic disease. Metastatic RCC has a poor prognosis. Traditional treatment modalities like chemo- and radiotherapy show overall response percentages of 2-6%. In view of the observed spontaneous remissions of advanced renal cancer, immune mechanisms have been suggested to play a role in the natural disease course of RCC. At present, several non-specific cytokine regimens are used in the treatment of mRCC, e.g. interleukin-2 and interferon-alpha, in combination or as monotherapy or in combination with substances like 13-cis-retinoic acid and/or 5-fluorouracil. Collective data of trials evaluating cytokine-based therapies for mRCC show an overall response rate of approximately 15%, with 5% of the patients showing complete responses. More importantly, cytokine treatment clearly translates into a significant survival benefit in a subset of patients. Nevertheless, the toxicity profile of these cytokine regimens is significant. With the enhanced knowledge of tumor-immunology, the identification of immunogenic tumor proteins, and antibodies recognizing tumor-associated antigens, new treatment strategies with increased specificity and fewer side effects are of interest. Here we review the different immunotherapeutical modalities currently used as well as new approaches for the treatment of advanced RCC.

MDR1 gene expression in hepatocellular carcinoma and the peritumoral liver of patients with and without cirrhosis

P-glycoprotein (P-gp) and MDR1 mRNA expressions were assessed in tumoral and peritumoral specimens from patients with hepatocellular carcinoma (HCC) and in cirrhotic livers without HCC, using immunohistochemistry (C494 monoclonal antibody) and reverse transcription-polymerase chain reaction (RT-PCR) analysis. P-gp overexpression was detected in 24/28 tumoral livers (85%). In the peritumoral liver, staining was strong in cirrhotic nodules, and fainter in non-cirrhotic specimens. P-gp expression was as intense in the cirrhotic specimens free of HCC as in the peritumoral tissue of HCC developing in cirrhotic patients. These results were confirmed by RT-PCR analysis.

MDR1 gene expression in peripheral blood mononuclear cells after liver transplantation

BACKGROUND

The multidrug resistance pump, P-glycoprotein 170 (P-gp), the MDR1 gene expression product, is expressed in peripheral blood mononuclear cells (PBMC). Cyclosporine (CsA) and tacrolimus are inhibitors and substrates of the pump, and can induce its expression. The aim of the present study was to assess MDR1 gene expression in PBMC after liver transplantation.

METHODS

P-gp expression was examined in PBMC from 23 adult patients by flow cytometry analysis using UIC2, a monoclonal anti-Pgp antibody, on days 7, 14, 21, 28, 90, and 180, and whenever a rejection episode was suspected. MDR1 mRNA was estimated by reverse transcription-polymerase chain reaction.

RESULTS

P-gp expression, assessed as the ratio of the mean fluorescence, increased from 1.59 before transplantation to 2.05 after transplantation, and did not vary significantly thereafter. There was no significant difference in P-gp expression between CsA and tacrolimus-based treatments. MDR1 mRNA levels did not vary significantly under CsA or tacrolimus therapy until day 28. P-gp expression was marginally higher in patients before acute rejection (P=0.054), and was lower in patients with severe infection (P=0.003) than in those with uneventful evolution. Alcoholic patients exhibited higher levels of P-gp expression than other patients.

CONCLUSION

P-gp expression increases after liver transplantation. Its variations do not allow the ability to predict acute rejection, but could help in making the diagnosis of overimmunosuppression.

p53 over-expression identifies a subset of nodal peripheral T-cell lymphomas with a distinctive biological profile and poor clinical outcome

Peripheral T-cell lymphomas (PTCL) are usually characterized by aggressive clinical behaviour and poor clinical outcome, but their biological background has not been extensively investigated to date, due to their low incidence, about 10% of all non-Hodgkin's lymphoma cases in Western countries, and also to the paucity of specific molecular-genetic abnormalities. Neverthless, there is increasing biological and clinical evidence that primary nodal PTCL should be considered separately from extra-nodal cases, but little is known about biological factors of possible clinical and prognostic impact. This immunohistochemical study has analysed the expression of p53, Mdm2, p21(WAF1), BCL-2 and p-glycoprotein (MDR-1 gene product) in a series of 45 cases of nodal peripheral T-cell lymphomas (PTCL) with 'high-grade' histology. The immunohistochemical findings were then correlated with proliferative activity and clinical outcome. p53 was over-expressed in 13 cases (28.9%). p53 positive cases showed significantly higher proliferative activity (p<0.01), more frequent expression of Bcl-2 (p<0.01) and less frequent expression of p21(WAF1) than p53 negative cases. Mdm2 and p-glycoprotein were expressed in 4/13 (30.8%) and 8/13 (61.5%) p53 positive cases respectively, and in none (0%) of the p53 negative cases (p<0.01). Analysis of the survival curves showed that p53 positive cases were associated with a significantly poorer clinical outcome than p53 negative cases, in terms of both overall survival (p=0.0032) and event-free survival (p=0.0004). Furthermore, multivariate analysis showed that p53 expression was the most important independent prognostic variable. These findings indicate that p53 over-expression identifies a subset of nodal PTCL cases with a distinctive biological profile (higher proliferative activity, less frequent expression of p21(WAF1) and more frequent expression of Bcl-2, Mdm2 and p-glycoprotein than p53 negative cases) and poor clinical outcome. The immunohistochemical analysis of p53 expression is a simple, rapid and low-cost method which may provide information of potential clinical and prognostic value in nodal peripheral T-cell lymphomas.

Increased intracellular doxorubicin by anti-FAS monoclonal antibody: a mechanism that enhances the cytotoxicity in renal cell carcinoma cells

OBJECTIVES

To investigate the effect of anti-Fas monoclonal antibody (mAb) on the intracellular concentration of doxorubicin in renal cell carcinoma (RCC) cells. Little is known about the influence of anti-Fas mAb on the intracellular concentration of chemotherapeutic agents.

METHODS

The concentration of intracellular doxorubicin was determined by high-performance liquid chromatography. The mRNA and protein levels of multidrug resistance-associated protein gene were evaluated by reverse transcriptase-polymerase chain reaction and immunocytochemistry, respectively.

RESULTS

An increased concentration of doxorubicin inside the cells was found: 2.4-fold in ACHN cells (a human RCC cell line) after treatment with doxorubicin combined with anti-Fas mAb compared with doxorubicin alone. Of the five cases of freshly derived RCC cells treated with doxorubicin and anti-Fas mAb, the intracellular concentration of doxorubicin was increased 2.3 and 2.7-fold in two of them, respectively. Furthermore, both the mRNA and the protein levels of the multidrug resistance-associated protein gene were downregulated after treatment of ACHN cells with anti-Fas mAb. Treatment of ACHN cells with a combination of anti-Fas mAb and doxorubicin resulted in a potentiation of the doxorubicin-mediated cytotoxicity.

CONCLUSIONS

The increased intracellular concentration of doxorubicin by anti-Fas mAb might be one of the mechanisms responsible for the enhancement of doxorubicin-mediated cytotoxicity in RCC cells.

Multidrug resistance gene 1 expression in salivary gland adenocarcinomas and oral squamous-cell carcinomas

In combined chemotherapy for head-and-neck cancer (HNC), salivary gland-cell adenocarcinoma (SGA) shows insufficient clinical outcome, and it has been suggested that the sensitivity and/or the mechanism of resistance to anti-cancer drugs are different between SGA and oral squamous-cell carcinoma (SCC). The aim of our study was to clarify whether P-glycoprotein (P-gp) expression is associated with multidrug resistance (MDR) in HNC and the difference in the process of its development between SGA and SCC. In immunohistochemical analysis, P-gp expression was found in the ductal cells of salivary glands but not in oral mucosal epithelium. In cancer tissues, a few SCC cells in 12 of 37 and most cells in all SGAs expressed P-gp. The intensive P-gp expression was significantly found in SGA compared with SCC. In an in vivo chemotherapeutic model using tumor-bearing nude mice, P-gp expression in counterparts was observed in only a few cells of the HSY line, while no P-gp expression was observed in Hepd cells. However, P-gp expression was developed in both HSY and Hepd cell lines after vincristine (VCR) treatment. RT-PCR showed that the mean ratios of mdr1 mRNA expression levels in HSY clones were 3.7-fold higher than those in Hepd clones after VCR treatment, while each cell line exhibited both induction and activated production of P-gp. These results suggest that P-gp-related MDR in SGA is an inherent phenotype caused by both high levels of P-gp induction and activated P-gp production during VCR treatment, while that in SCC is an acquired phenotype chiefly caused by induction of P-gp.

Chemotherapy resistance in acute myeloid leukaemia

The development of refractory disease in acute myeloid leukaemia (AML) is frequently associated with the expression of one or several multidrug resistance (MDR) genes. MDR1, MRP1 and LRP have been identified as important adverse prognostic factors in AML. Recently it has become possible to reverse clinical multidrug resistance by blocking P-glycoprotein-mediated drug efflux. The potential relevance of MDR and new approaches to treat refractory disease, are discussed.

Expression of multidrug resistance-associated protein (MRP) in human gliomas

Drug resistance is a major clinical problem in the chemotherapy of human gliomas. The multidrug resistance-associated protein (MRP), a membrane transporter related to non-P-glycoprotein multidrug resistance, is overexpressed in some drug-selected cancer cell lines. To investigate whether MRP is involved in the intrinsic drug resistance of human gliomas, surgical specimens of 20 gliomas (11 glioblastomas, 6 anaplastic astrocytomas, and 3 astrocytomas), 3 normal brain specimens, and 4 glioma cell lines (U87MG, U251MG, U373MG, and T98G) were analyzed. The expression of MRP was studied by RT-PCR and immunohistochemistry in the surgical specimens. The MRP expression levels in the cell lines were assessed by the quantitative RT-PCR and Western blot analyses. Sensitivity to adriamycin (ADM), etoposide (VP-16), cisplatin (CDDP), and 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea (ACNU), were determined by MTT assay, and antisense treatment was evaluated in the cell lines. The expression of MRP was detected in 9 of 11 glioblastomas and 3 of 6 anaplastic astrocytomas. The quantitative analyses of the cell lines revealed that the MRP mRNA and protein levels were increased 4.5-fold in the T98G cells as compared to U87MG. T98G cells showed the highest resistance to all drugs. Western blot analysis revealed that treatment with the antisense oligonucleotide reduced the level of MRP expression to 25% of the sense oligonucleotide treatment in T98G cells. The sensitivity to ADM, VP-16 and CDDP was significantly increased in the antisense-treated cells as compared with the sense-treated cells. These results suggest that the MRP expression may be related to the intrinsic multidrug resistance in human gliomas.