The TGFBI gene and protein expression in topotecan resistant ovarian cancer cell lines

PURPOSE

The primary limiting factor in achieving cures for patients with cancer, particularly ovarian cancer, is drug resistance. The mechanisms of drug resistance of cancer cells during chemotherapy may include compounds of the extracellular matrix, such as the transforming growth factor-beta-induced protein (TGFBI). In this study, we aimed to analyze the TGFBI gene and protein expression in different sensitive and drug-resistant ovarian cancer cell lines, as well as test if TGFBI can be involved in the response to topotecan (TOP) at the very early stages of treatment.

MATERIALS AND METHODS

In this study, we conducted a detailed analysis of TGFBI expression in different ovarian cancer cell lines (A2780, A2780TR1, A2780TR2, W1, W1TR, SKOV-3, PEA1, PEA2 and PEO23). The level of TGFBI mRNA (QPCR), intracellular and extracellular protein (Western blot analysis) were assessed in this study.

RESULTS

We observed upregulation of TGFBI mRNA in drug-resistant cell lines and estrogen-receptor positive cell lines, which was supported by overexpression of both intracellular and extracellular TGFBI protein. We also showed the TGFBI expression after a short period of treatment of sensitive ovarian cancer cell lines with TOP.

CONCLUSION

The expression of TGFBI in ovarian cancer cell lines suggests its role in the development of drug resistance.

The response and resistance to drugs in ovarian cancer cell lines in 2D monolayers and 3D spheroids

Ovarian cancer is the most common type of gynecologic cancer. One of the leading causes of high mortality is chemoresistance, developed primarily or during treatment. Different mechanisms of drug resistance appear at the cellular and cancer tissue organization levels. We examined the differences in response to the cytotoxic drugs CIS, MTX, DOX, VIN, PAC, and TOP using 2D (two-dimensional) and 3D (three-dimensional) culture methods. We tested the drug-sensitive ovarian cancer cell line W1 and established resistant cell lines to appropriate cytotoxic drugs. The following qualitative and quantitative methods were used to assess: 1) morphology - inverted microscope and hematoxylin & eosin staining; 2) viability - MTT assay; 3) gene expression - a quantitative polymerase chain reaction; 4) identification of proteins - immunohistochemistry, and immunofluorescence. Our results indicate that the drug-sensitive and drug-resistant cells cultured in 3D conditions exhibit stronger resistance than the cells cultured in 2D conditions. A traditional 2D model shows that drug resistance of cancer cells is caused mainly by changes in the expression of genes encoding ATP-binding cassette transporter proteins, components of the extracellular matrix, "new" established genes related to drug resistance in ovarian cancer cell lines, and universal marker of cancer stem cells. Whereas in a 3D model, the drug resistance in spheroids can be related to other mechanisms such as the structure of the spheroid (dense or loose), the cell type (necrotic, quiescent, proliferating cells), drug concentrations or drug diffusion into the dense cellular/ECM structure.

The significance of interferon gamma inducible protein 16 (IFI16) expression in drug resistant ovarian cancer cell lines

BACKGROUND

Inherent or developed during treatment drug resistance is the main reason for the low effectiveness of chemotherapy in ovarian cancer. IFI16 is a cytoplasmic/nuclear protein involved in response to virus's infection and cell cycle arrest associated with the cellular senescence.

METHODS

Here we performed a detailed IFI16 expression analysis in ovarian cancer cell lines sensitive (A2780) and resistant to doxorubicin (DOX) (A2780DR1 and A2780DR2) and paclitaxel (PAC) (A2780PR1). IFI16 mRNA level, protein level in the nuclear and cytoplasmic fraction (Western blot analysis), the protein expression in cancer cells and nuclei (immunofluorescence analysis) and cancer patient lesions (immunohistochemistry) were performed in this study.

RESULTS

We observed upregulation of IFI16 expression in drug resistant cell lines with dominant cytoplasmic localization in DOX-resistant cell lines and nuclear one in the PAC-resistant cell line. The most abundantly overexpressed isoforms of IFI16 were IFI16A and IFI16C. Finally, an analysis of a histological type of ovarian cancer (immunohistochemistry) showed expression in serous ovarian cancer.

CONCLUSIONS

Expression of IFI16 in drug-resistant cell lines suggests its role in drug resistance development in ovarian cancer. Expression in serous ovarian cancer suggests its role in the pathogenesis of this histological type.

Piperine Targets Different Drug Resistance Mechanisms in Human Ovarian Cancer Cell Lines Leading to Increased Sensitivity to Cytotoxic Drugs

Our goal was to examine the anticancer effects of piperine against the resistant human ovarian cancer cells and to explore the molecular mechanisms responsible for its anticancer effects. Our study used drug-sensitive ovarian cancer cell line W1 and its sublines resistant to paclitaxel (PAC) and topotecan (TOP). We analyzed the cytotoxic effect of piperine and cytostatic drugs using an MTT assay. The impact of piperine on protein expression was determined by immunofluorescence and Western blot. We also examined its effect on cell proliferation and migration. We noticed a different level of piperine resistance between cell lines. Piperine increases the cytotoxic effect of PAC and TOP in drug-resistant cells. We observed an increase in PTPRK expression correlated with decreased pTYR level after piperine treatment and downregulation of P-gp and BCRP expression. We also noted a decrease in COL3A1 and TGFBI expression in investigated cell lines and increased COL3A1 expression in media from W1PR2 cells. The expression of Ki67 protein and cell proliferation rate decreased after piperine treatment. Piperine markedly inhibited W1TR cell migration. Piperine can be considered a potential anticancer agent that can increase chemotherapy effectiveness in cancer patients.

Insight into Cisplatin-Resistance Signaling of W1 Ovarian Cancer Cells Emerges mTOR and HSP27 as Targets for Sensitization Strategies

The microenvironment possesses a strong impact on the tumor chemoresistance when cells bind to components of the extracellular matrix. Here we elucidate the signaling pathways of cisplatin resistance in W1 ovarian cancer cells binding to collagen type 1 (COL1) and signaling interference with constitutive cisplatin resistance in W1CR cells to discover the targets for sensitization. Proteome kinase arrays and Western blots were used to identify the signaling components, their impact on cisplatin resistance was evaluated by inhibitory or knockdown approaches. W1 cell binding to COL1 upregulates integrin-associated signals via FAK/PRAS40/mTOR, confirmed by β1-integrin (ITGB1) knockdown. mTOR appears as key for resistance, its blockade reversed COL1 effects on W1 cell resistance completely. W1CR cells compensate ITGB1-knockdown by upregulation of discoidin domain receptor 1 (DDR1) as alternative COL1 sensor. COL1 binding via DDR1 activates the MAPK pathway, of which JNK1/2 appears critical for COL1-mediated resistance. JNK1/2 inhibition inverts COL1 effects in W1CR cells, whereas intrinsic cisplatin resistance remained unaffected. Remarkably, knockdown of HSP27, another downstream MAPK pathway component overcomes intrinsic resistance completely sensitizing W1CR cells to the level of W1 cells for cisplatin cytotoxicity. Our data confirm the independent regulation of matrix-induced and intrinsic chemoresistance in W1 ovarian cancer cells and offer novel targets for sensitization.

The Impact of Integrin-Mediated Matrix Adhesion on Cisplatin Resistance of W1 Ovarian Cancer Cells

BACKGROUND

Tumor cell binding to the microenvironment is regarded as the onset of therapeutic resistance, referred to as cell adhesion mediated drug resistance (CAM-DR). Here we elucidate whether CAM-DR occurs in ovarian cancer cells and contributes to still-existing cisplatin resistance.

METHODS

Cultivation of W1 and cisplatin-resistant W1CR human ovarian cancer cells on collagen-type I (COL1) was followed by whole genome arrays, MTT assays focusing cisplatin cytotoxicity, and AAS detection of intracellular platinum levels. Expression of cisplatin transporters Ctr1 and MRP2 was analyzed. Mechanistic insight was provided by lentiviral β1-integrin (ITGB1) knockdown, or inhibition of integrin-linked kinase (ILK).

RESULTS

EC₅₀ values of cisplatin cytotoxicity increased twofold when W1 and W1CR cells were cultivated on COL1, associated with significantly diminished intracellular platinum levels. Transporter deregulation could not be detected at mRNA levels but appears partially responsible at protein levels. The ITGB1 knockdown confirms that CAM-DR follows a COL1/ITGB1 signaling axis in W1 cells; thus, a blockade of ILK re-sensitized W1 cells on COL1 for cisplatin. In contrast, CAM-DR adds to cisplatin resistance in W1CR cells independent of ITGB1.

CONCLUSIONS

CAM-DR appears relevant for ovarian cancer cells, adding to existing genetic resistance and thus emerges as a target for sensitization strategies.

Expression of Osteoblast-Specific Factor 2 (OSF-2, Periostin) Is Associated with Drug Resistance in Ovarian Cancer Cell Lines

One of the main obstacles to the effective treatment of ovarian cancer patients continues to be the drug resistance of cancer cells. Osteoblast-Specific Factor 2 (OSF-2, Periostin) is a secreted extracellular matrix protein (ECM) expressed in fibroblasts during bone and teeth development. Expression of OSF-2 has been also related to the progression and drug resistance of different tumors. The present study investigated the role of OSF-2 by evaluating its expression in the primary serous ovarian cancer cell line, sensitive (W1) and resistant to doxorubicin (DOX) (W1DR) and methotrexate (MTX) (W1MR). The OSF-2 transcript (real-time PCR analysis), protein expression in cell lysates and cell culture medium (western blot), and expression of the OSF-2 protein in cell lines (immunofluorescence) were investigated in this study. Increased expression of OSF-2 mRNA was observed in drug-resistant cells and followed by increased protein expression in cell culture media of drug-resistant cell lines. A subpopulation of ALDH1A1-positive cells was noted for W1DR and W1MR cell lines; however, no direct co-expression with OSF-2 was demonstrated. Both drugs induced OSF-2 expression after a short period of exposure of the drug-sensitive cell line to DOX and MTX. The obtained results indicate that OSF-2 expression might be associated with the development of DOX and MTX resistance in the primary serous W1 ovarian cancer cell line.

PTPRK Expression Is Downregulated in Drug Resistant Ovarian Cancer Cell Lines, and Especially in ALDH1A1 Positive CSCs-Like Populations

Background: Ovarian cancer is the 7th most common cancer and 8th most mortal cancer among woman. The standard treatment includes cytoreduction surgery followed by chemotherapy. Unfortunately, in most cases, after treatment, cancer develops drug resistance. Decreased expression and/or activity of protein phosphatases leads to increased signal transduction and development of drug resistance in cancer cells. Methods: Using sensitive (W1, A2780) and resistant ovarian cancer cell lines, the expression of Protein Tyrosine Phosphatase Receptor Type K (PTPRK) was performed at the mRNA (real-time PCR analysis) and protein level (Western blot, immunofluorescence analysis). The protein expression in ovarian cancer tissues was determined by immunohistochemistry. Results: The results showed a decreased level of PTPRK expression in ovarian cancer cell lines resistant to cisplatin (CIS), paclitaxel (PAC), doxorubicin (DOX), topotecan (TOP), vincristine (VIN) and methotrexate (MTX). Additionally, the lower PTPRK expression was observed in Aldehyde Dehydrogenase 1 Family Member A1 (ALDH1A1) positive cancer stem cells (CSCs) population, suggesting the role of PTPRK downregulation in primary as well as acquired resistance to cytotoxic drugs. Conclusions: These results provide important insights into the role of PTPRK in mechanism leading to drug resistance in ovarian cancer and has raised important questions about the role of imbalance in processes of phosphorylation and dephosphorylation.

Myotilin, a New Topotecan Resistant Protein in Ovarian Cancer Cell Lines

Background: Low effectiveness of chemotherapy in ovarian cancer results from development of drug resistance during treatment. Topotecan (TOP) is a chemotherapeutic drug used in second-line chemotherapy of this cancer. Unfortunately, during treatment cancer can develop diverse cellular and tissue specific mechanisms of resistance to cytotoxic drugs.

Methods: We analyzed development of TOP resistance in ovarian cancer cell lines (A2780 and W1). On the base of our previous results where a set of “new genes” with different functions that can be related to TOP-resistance was described hereby we performed detailed analysis of MYOT expression. MYOT mRNA level (real time PCR analysis), protein expression in cell lysates and cell culture medium (western blot analysis) and protein expression in cancer cells (immunofluorescence analysis) were determined in this study.

Results: We observed increased expression of MYOT in TOP resistant cell lines at both mRNA and protein level. MYOT, together with extracellular matrix molecules like COL1A2 and COL15A1 were also secreted to corresponding cell culture media.

Conclusion: Our results suggest that upregulation of MYOT can be related to TOP resistance in ovarian cancer cell lines.

The Role of Matrix Gla Protein (MGP) Expression in Paclitaxel and Topotecan Resistant Ovarian Cancer Cell Lines

The major cause of ovarian cancer treatment failure in cancer patients is inherent or acquired during treatment drug resistance of cancer. Matrix Gla protein (MGP) is a secreted, non-collagenous extracellular matrix protein involved in inhibition of tissue calcification. Recently, MGP expression was related to cellular differentiation and tumor progression. A detailed MGP expression analysis in sensitive (A2780) and resistant to paclitaxel (PAC) (A2780PR) and topotecan (TOP) (A2780TR) ovarian cancer cell lines and their corresponding media was performed. MGP mRNA level (real time PCR analysis) and protein expression in cell lysates and cell culture medium (Western blot analysis) and protein expression in cancer cells (immunofluorescence analysis) and cancer patient lesions (immunohistochemistry) were determined in this study. We observed increased expression of MGP in PAC and TOP resistant cell lines at both mRNA and protein level. MGP protein was also detected in the corresponding culture media. Finally, we detected expression of MGP protein in ovarian cancer lesions from different histological type of cancer. MGP is an important factor that might contribute to cancer resistance mechanism by augmenting the interaction of cells with ECM components leading to increased resistance of ovarian cancer cells to paclitaxel and topotecan. Expression found in ovarian cancer tissue suggests its possible role in ovarian cancer pathogenesis.

Microarray-based detection and expression analysis of new genes associated with drug resistance in ovarian cancer cell lines

PURPOSE

The present study is to discover a new genes associated with drug resistance development in ovarian cancer.

METHODS

We used microarray analysis to determine alterations in the level of expression of genes in cisplatin- (CisPt), doxorubicin- (Dox), topotecan- (Top), and paclitaxel- (Pac) resistant variants of W1 and A2780 ovarian cancer cell lines. Immunohistochemistry assay was used to determine protein expression in ovarian cancer patients.

RESULTS

We observed alterations in the expression of 22 genes that were common to all three cell lines that were resistant to the same cytostatic drug. The level of expression of 13 genes was upregulated and that of nine genes was downregulated. In the CisPt-resistant cell line, we observed downregulated expression of ABCC6, BST2, ERAP2 and MCTP1; in the Pac-resistant cell line, we observe upregulated expression of ABCB1, EPHA7 and RUNDC3B and downregulated expression of LIPG, MCTP1, NSBP1, PCDH9, PTPRK and SEMA3A. The expression levels of three genes, ABCB1, ABCB4 and IFI16, were upregulated in the Dox-resistant cell lines. In the Top-resistant cell lines, we observed increased expression levels of ABCG2, HERC5, IFIH1, MYOT, S100A3, SAMD4A, SPP1 and TGFBI and decreased expression levels of MCTP1 and PTPRK. The expression of EPHA7, IFI16, SPP1 and TGFBI was confirmed at protein level in analyzed ovarian cancer patients..

CONCLUSIONS

The expression profiles of the investigated cell lines indicated that new candidate genes are related to the development of resistance to the cytostatic drugs that are used in first- and second-line chemotherapy of ovarian cancer.

New and Old Genes Associated with Primary and Established Responses to Paclitaxel Treatment in Ovarian Cancer Cell Lines

Development of drug resistance is the main reason for low chemotherapy effectiveness in treating ovarian cancer. Paclitaxel (PAC) is a chemotherapeutic drug used in the treatment of this cancer. We analysed the development of PAC resistance in two ovarian cancer cell lines. Exposure of drug-sensitive cell lines (A2780 and W1) to PAC was used to determine the primary response. An established response was determined in PAC-resistant sublines of the A2780 and W1 cell lines. qRT-PCR was performed to measure the expression levels of specific genes. We observed decreased expression of the PCDH9, NSBP1, MCTP1 and SEMA3A genes in the PAC-resistant cell lines. Short-term exposure to PAC led to increased expression of the MDR1 and BCRP genes in the A2780 and W1 cell lines. In the A2780 cell line, we also observed increased expression of the C4orf18 gene and decreased expression of the PCDH9 and SEMA3A genes after PAC treatment. In the W1 cell line, short-term treatment with PAC upregulated the expression of the ALDH1A1 gene, a marker of Cancer stem cells (CSCs). Our results suggest that downregulation of the PCDH9, NSBP1, MCTP1 and SEMA3A genes and upregulation of the MDR1, BCRP, C4orf18 and ALDH1A1 genes may be related to PAC resistance.

Analysis of defective protein ubiquitylation associated to adriamycin resistant cells

DNA damage activated by Adriamycin (ADR) promotes ubiquitin-proteasome system-mediated proteolysis by stimulating both the activity of ubiquitylating enzymes and the proteasome. In ADR-resistant breast cancer MCF7 (MCF7^ADR) cells, protein ubiquitylation is significantly reduced compared to the parental MCF7 cells. Here, we used tandem ubiquitin-binding entities (TUBEs) to analyze the ubiquitylation pattern observed in MCF7 or MCF7^ADR cells. While in MCF7, the level of total ubiquitylation increased up to six-fold in response to ADR, in MCF7^ADR cells only a two-fold response was found. To further explore these differences, we looked for cellular factors presenting ubiquitylation defects in MCF7^ADR cells. Among them, we found the tumor suppressor p53 and its ubiquitin ligase, Mdm2. We also observed a drastic decrease of proteins known to integrate the TUBE-associated ubiquitin proteome after ADR treatment of MCF7 cells, like histone H2AX, HMGB1 or β-tubulin. Only the proteasome inhibitor MG132, but not the autophagy inhibitor chloroquine partially recovers the levels of total protein ubiquitylation in MCF7^ADR cells. p53 ubiquitylation is markedly increased in MCF7^ADR cells after proteasome inhibition or a short treatment with the isopeptidase inhibitor PR619, suggesting an active role of these enzymes in the regulation of this tumor suppressor. Notably, MG132 alone increases apoptosis of MCF7^ADR and multidrug resistant ovarian cancer A2780DR1 and A2780DR2 cells. Altogether, our results highlight the use of ubiquitylation defects to predict resistance to ADR and underline the potential of proteasome inhibitors to treat these chemoresistant cells.

New and Old Genes Associated with Primary and Established Responses to Cisplatin and Topotecan Treatment in Ovarian Cancer Cell Lines

Low efficiency of chemotherapy in ovarian cancer results from the development of drug resistance. Cisplatin (CIS) and topotecan (TOP) are drugs used in chemotherapy of this cancer. We analyzed the development of CIS and TOP resistance in ovarian cancer cell lines. Incubation of drug sensitive cell lines (W1 and A2780) with cytostatic drugs was used to determine the primary response to CIS and TOP. Quantitative polymerase chain reaction (Q-PCR) was performed to measure the expression levels of the genes. We observed decreased expression of the MCTP1 gene in all resistant cell lines. We observed overexpression of the S100A3 and HERC5 genes in TOP-resistant cell lines. Increased expression of the S100A3 gene was also observed in CIS-resistant A2780 sublines. Overexpression of the C4orf18 gene was observed in CIS- and TOP-resistant A2780 sublines. A short time of exposure to CIS led to increased expression of the ABCC2 gene in the W1 and A2780 cell lines and increased expression of the C4orf18 gene in the A2780 cell line. A short time of exposure to TOP led to increased expression of the S100A3 and HERC5 genes in both sensitive cell lines, increased expression of the C4orf18 gene in the A2780 cell line and downregulation of the MCTP1 gene in the W1 cell line. Our results suggest that changes in expression of the MCTP1, S100A3 and C4orf18 genes may be related to both CIS and TOP resistance. Increased expression of the HERC5 gene seems to be important only in TOP resistance.

Analysis of MDR genes expression and cross-resistance in eight drug resistant ovarian cancer cell lines

Background

Multiple drug resistance (MDR) of cancer cells is the main reason of intrinsic or acquired insensitivity to chemotherapy in many cancers. In this study we used ovarian cancer model of acquired drug resistance to study development of MDR.

We have developed eight drug resistant cell lines from A2780 ovarian cancer cell line: two cell lines resistant to each drug commonly used in ovarian cancer chemotherapy: cisplatin (CIS), paclitaxel (PAC), doxorubicin (DOX) and topotecan (TOP). A chemosensitivity assay - MTT was performed to assess drug cross-resistance. Quantitative real-time polymerase chain reaction and immunofluorescence were also performed to determine mRNA and protein expression of genes/proteins involved in drug resistance (P-gp, BCRP, MRP1, MRP2, MVP). Flow cytometry was used to determine the activity of drug transporters.

Results

We could observe cross-resistance between PAC- and DOX-resistant cell lines. Additionally, both PAC-resistant cell lines were cross-resistant to TOP and both TOP-resistant cell lines were cross-resistant to DOX. We observed two different mechanisms of resistance to TOP related to P-gp and BCRP expression and activity. P-gp and BCRP were also involved in DOX resistance. Expression of MRP2 was increased in CIS-resistant cell lines and increased MVP expression was observed in CIS-, PAC- and TOP-, but not in DOX-resistant cell lines.

Conclusions

Effectiveness of TOP and DOX in second line of chemotherapy in ovarian cancer can be limited because of their cross-resistance to PAC. Moreover, cross-resistance of PAC-resistant cell line to CIS suggests that such interaction between those drugs might also be probable in clinic.

Increased Expression of Several Collagen Genes is Associated with Drug Resistance in Ovarian Cancer Cell Lines

Ovarian cancer is the most lethal gynaecological cancer. The main reason for the high mortality among ovarian cancer patients is the development of drug resistance. The expression of collagen genes by cancer cells can increase drug resistance by inhibiting the penetration of the drug into the cancer tissue as well as increase apoptosis resistance. In this study, we present data that shows differential expression levels of collagen genes and proteins in cisplatin- (CIS), paclitaxel- (PAC), doxorubicin- (DOX), topotecan- (TOP), vincristine- (VIN) and methotrexate- (MTX) resistant ovarian cancer cell lines. Quantitative real-time polymerase chain reactions were performed to determine the mRNA levels. Protein expression was detected using Western blot and immunocytochemistry assays. In the drug resistant cell lines, we observed the upregulation of eight collagen genes at the mRNA level and based on these expression levels, we divided the collagen genes into the following three groups:

1. Genes with less than a 50-fold increase in expression: COL1A1, COL5A2, COL12A1 and COL17A1. 2. Genes with greater than a 50-fold increase in expression: COL1A2, COL15A1 and COL21A1. 3. Gene with a very high level of expression: COL3A1. Expression of collagen (COL) proteins from groups 2 and 3 were also confirmed using immunocytochemistry. Western blot analysis showed very high expression levels of COL3A1 protein, and immunocytochemistry analysis showed the presence of extracellular COL3A1 in the W1TR cell line. The cells mainly responsible for the extracellular COL3A1 production are aldehyde dehydrogenase-1A1 (ALDH1A1) positive cells. All correlations between the types of cytostatic drugs and the expression levels of different COL genes were studied, and our results suggest that the expression of fibrillar collagens may be involved in the TOP and PAC resistance of the ovarian cancer cells. The expression pattern of COL genes provide a preliminary view into the role of these proteins in cytostatic drug resistance of cancer cells. The exact role of these COL genes in drug resistance requires further investigation.

Effect of brefeldin A and castanospermine on resistant cell lines as supplements in anticancer therapy

In the present study, we analyzed the influence of brefeldin A (BFA) and castanospermine (CAS) on the activity, stability and localization of P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) in various resistant cell lines. The impact of BFA and CAS on cell viability was assessed using the MTT test. Western blotting (WB) was performed to assess the effect of the inhibitors on the expression of the investigated proteins. Immunofluorescence was employed to assess the effect of BFA and CAS on the cellular localization of the proteins. Flow cytometry was used to verify the functional role of inhibitors on drug uptake and efflux. The MTT test showed that BFA had a significant effect on cell viability in LoVo/Dx and W1PR cell lines. WB analysis demonstrated that BFA partially blocked Pgp N-glycosylation and induced BCRP degradation and CASP 3-dependent apoptosis in W1TR cells; however, the BFA activity was p53-independent. CAS had no effect on the stability of Pgp but increased the level of non-glycosylated BCRP. The expression of p53 protein decreased in all of the cells that were treated with CAS. Immunofluorescence revealed that BFA caused a more granular Pgp signal in W1PR and BCRP in A2780T1 cells. Furthermore, BFA caused morphological changes in LoVo/Dx and W1TR cell lines. CAS also induced a granular signal in all of the cell lines, except W1TR. The flow cytometry showed higher dye accumulation in sensitive cell lines. We observed an increase in the mean fluorescence intensity (MFI) of Rho123 in LoVo/Dx cells treated with BFA and CAS, but no differences were observed in W1PR. BFA had no effect on the MFI of W1TR, but CAS led to an increase in the level of intracellular H33342 in W1TR and A2780T1 cells. These results suggest that these compounds are likely to be useful as supplements in anticancer therapy.

Inhibition of protein glycosylation reverses the MDR phenotype of cancer cell lines

BACKGROUND

Multidrug resistance proteins are one of the most important factors that cause chemotherapy resistance, which in turn reduces therapeutic efficacy and survival for cancer patients. Tunicamycin is one of the most well-known inhibitors of N-glycosylation and is considered a powerful adjunct that can increase the effectiveness of many drugs. Tunicamycin blocks the first step of P-gp (glycoprotein P) and BCRP (breast cancer resistance protein) N-glycosylation, which is a very important modification for the activity and cellular localisation of these proteins.

METHODS

The effects of tunicamycin on ovarian and colorectal cancer cells were examined in multiple cell lines. The primary ovarian cancer cell line W1 and the established ovarian cancer cell line A2780 were compared against their drug-resistant derivatives W1TR/W1PR (TR: topotecan resistant; PR: paclitaxel resistant) and A2780T1 (topotecan resistant), respectively. We also compared the colorectal cancer cell line LoVo against its doxorubicin-resistant derivative LoVo/Dx. Cell viability was determined by the MTT assay. The glycopeptides were subjected to deglycosylation using the endoglycosidase PNGase F. A2780T1, LoVo/Dx and W1PR cells were treated with the protein degradation inhibitors MG132 and BMA. Protein expression was detected by western blot and immunocytochemistry.

RESULTS

In this study, we showed via the MTT assay that tunicamycin significantly decreased the viability of cancer cell lines that were co-treated with a chemotherapeutic drug. Western blot analysis showed that, in LoVo/Dx and W1PR cells, tunicamycin treatment resulted in the expression of a 70kDa P-gp protein instead of the mature 170kDa P-gp. Treatment with MG132 or BMA fully suppressed the effect of tunicamycin in the case of W1PR cells only. In tunicamycin-treated W1TR cells, the size of the BCRP protein did not differ from that of its native unglycosylated form. In tunicamycin-treated A2780T1 cells, BCRP expression was completely inhibited, but pre-treatment with MG132 or BMA suppressed the effect of tunicamycin. Immunocytochemistry analysis indicated that tunicamycin only affected the translocation of P-gp but not that of BCRP. After treatment, we observed higher P-gp expression in the cytoplasm than at the cell membrane.

CONCLUSIONS

Our results indicated that tunicamycin may enhance the effect of chemotherapy by interfering with the localisation and function of transporter proteins that are responsible for multidrug resistance.

The role of aldehyde dehydrogenase (ALDH) in cancer drug resistance

Chemotherapy in cancer patients is still not satisfactory because of drug resistance. The main mechanism of drug resistance results from the ability of cancer cells to actively expel therapeutic agents via transport proteins of the ABC family. ABCB1 and ABCG2 are the two main proteins responsible for drug resistance in cancers. Recent investigations indicate that aldehyde dehydrogenase (ALDH) can also be involved in drug resistance. Expression of the ABC transporters and ALDH enzymes is observed in normal stem cells, cancer stem cells and drug resistant cancers. Current chemotherapy regimens remove the bulk of the tumour but are usually not effective against cancer stem cells (CSCs) expressing ALDH. As a result, the number of ALDH positive drug resistant CSCs increases after chemotherapy. This indicates that therapies targeting drug resistant CSCs should be developed. A number of therapies targeting CSCs are currently under investigation. These therapies include differentiation therapy using different retinoic acids (RA) as simple agents or in combination with DNA methyltransferase inhibitors (DNMTi) and/or histone deacetylase inhibitors (HDACi). Therapies that target cancer stem cell signaling pathways are also under investigation. A number of natural compounds are effective against cancer stem cells and lead to decreasing numbers of ALDH positive cells and downregulation of the ABC proteins. Combinations of differentiation therapies or therapies targeting CSC signaling pathways with classical cytostatics seem promising. This review discusses the role of ALDH and ABC proteins in the development of drug resistance in cancer and current therapies designed to target CSCs.

Detection of a Short CCR5 Messenger RNA Isoform in Human Spermatozoa

It has recently been reported that the Regulated upon Activation of Normal T-cells Expressed and Secreted (RANTES) chemokine may exhibit a chemotactic effect on sperm. The RANTES chemokine acts on target cells by binding to the CCR5 receptor, which is present on the surface of various cells. Spermatozoa contain a complex repertoire of messenger RNAs (mRNAs) that may provide an insight into past events of spermatogenesis. The type and amount of CCR5 chemokine receptor transcript were investigated in spermatozoa that were isolated by the swim-up method from semen samples of men with normozoospermia. Using reverse transcription and real-time quantitative polymerase chain reaction (RQ-PCR) analysis, we found that the CCR5 mRNA isoform in human spermatozoa consists of exons 3 and 4, and is shorter than the transcript in leukocytes. This CCR5 transcript may represent a more stable mRNA isoform; one that is used to biosynthesize the CCR5 receptor in spermatogenesis or the early stages of embryonic development.

Microarray-based detection and expression analysis of ABC and SLC transporters in drug-resistant ovarian cancer cell lines

Multiple drug resistance of cancer cells is multifactorial. A microarray technique may provide information about new candidate genes playing a role in drug resistance. Drug membrane transporters from ABC and SLC families play a main role in this phenomenon. This study demonstrates alterations in ABC and SLC gene expression levels in methotrexate, cisplatin, doxorubicin, vincristine, topotecan and paclitaxel-resistant variant of W1 ovarian cancer cell line. Resistant W1 cell lines were derived by stepwise selection of cells in increasing concentration of drugs. Affymetrix GeneChip(®) Human Genome U219 Array Strip was used for hybridizations. Statistical significance was determined by independent sample t-test. The genes having altered expression levels in drug-resistant sublines were selected and filtered by scater plot. Genes up/downregulated more than threefolds were selected and listed. Among ABC genes, seven were upregulated and three were downregulated. Three genes: ABCB1, ABCB4 and ABCG2 were upregulated very significantly (over tenfold). One ABCA8 was significantly downregulated. Among 38 SLC genes, 18 were upregulated, 16 were downregulated and four were up- or downregulated dependent on the cell line. Expression of 10 SLC genes was changed very significantly (over tenfold). Four genes were significantly increased: SLC6A1, SLC9A2, SLC12A1, SLC16A6 and six genes were significantly decreased: SLC2A14, SLC7A3, SLC7A8, SLC7A11, SLC16A14, SLC38A9. Based on the expression profiles, our results provide a preliminary insight into the relationship between drug resistance and expression of membrane transporters involved in drug resistance. Correlation of specific drug transporter with drug resistance requires further analysis.

Inhibitors of N-glycosylation as a potential tool for analysis of the mechanism of action and cellular localisation of glycoprotein P

Multidrug resistance has for many years attracted attention of numerous investigators. Attempts have also been made to increase efficiency of anti-neoplastic therapy. For this reason, most of efforts have been devoted to analysing proteins engaged in the mechanism of multidrug resistance such as the N-glycosylated membrane protein glycoprotein P. Interestingly, glycosylation probably plays a significant role in the intracellular location and activity of modified proteins. Inhibitors of glycosylation have been demonstrated to alter the activity of glycoprotein P in various ways, depending on the cell line examined. These inhibitors markedly reduce multidrug resistance of cancer cells, thus promoting success of anti-neoplastic therapy. Here, we review the basic knowledge on N-glycosylation inhibitors, their effect on glycoprotein P and their therapeutic potential.

Inhibitors of N-glycosylation as a potential tool for analysis of the mechanism of action and cellular localisation of glycoprotein P

Multidrug resistance has for many years attracted attention of numerous investigators. Attempts have also been made to increase efficiency of anti-neoplastic therapy. For this reason, most of efforts have been devoted to analysing proteins engaged in the mechanism of multidrug resistance such as the N-glycosylated membrane protein glycoprotein P. Interestingly, glycosylation probably plays a significant role in the intracellular location and activity of modified proteins. Inhibitors of glycosylation have been demonstrated to alter the activity of glycoprotein P in various ways, depending on the cell line examined. These inhibitors markedly reduce multidrug resistance of cancer cells, thus promoting success of anti-neoplastic therapy. Here, we review the basic knowledge on N-glycosylation inhibitors, their effect on glycoprotein P and their therapeutic potential.

QUANTITATIVE ANALYSIS OF CCR5 CHEMOKINE RECEPTOR AND CYTOCHROME P450 AROMATASE TRANSCRIPTS IN SWIM-UP SPERMATOZOA ISOLATED FROM FERTILE AND INFERTILE MEN

We determined the CCR5 chemokine receptor and cytochrome P450 aromatase (P450arom) transcript copies number in swim-up sperm isolated from fertile and infertile men. The ejaculates were purified by centrifugation through discontinuous Percoll density gradient and swim-up techniques. RNA was isolated from sperm, treated with DNase I and reverse-transcribed into cDNA. Quantitative analysis of CCR5 and P450arom cDNA were performed by real-time quantitative (RQ-PCR) SYBR Green I analysis. There was a higher content of CCR5 and P450arom transcripts copy number in swim-up sperm of fertile than from infertile donors. The decrease in CCR5 and P450arom transcripts in swim-up sperm may be associated with male infertility.

Prevalence of ZAP-70, LAT, SLP-76, and DNA methyltransferase 1 expression in CD4+ T cells of patients with systemic lupus erythematosus

T cells from systemic lupus erythematosus (SLE) patients exhibit defective function of CD4(+) T cells that can be responsible for improper activation of B cells and antibody biosynthesis against host antigens. We compared the level of ZAP-70, LAT, and SLP-76, transcripts and proteins in CD4(+) T cells from SLE patients (n = 22) and healthy individuals (n = 15). We also determined DNA methyltransferase 1 (DNMT1) protein content in CD4(+) T cells of SLE patients. The CD4(+) T cells were isolated by positive biomagnetic separation technique. The quantitative analysis of messenger RNA (mRNA) was performed by reverse transcription and real-time quantitative polymerase chain reaction (RQ-PCR) SYBR Green I system. The protein level in the CD4(+) T cells was determined by Western blotting analysis. We found that the LAT protein level was significantly higher in SLE CD4(+) T cells than in controls (P = 0.006). Western blot analysis revealed that ZAP-70 protein content in SLE CD4(+) T cells may be reciprocally correlated with disease activity expressed in SLEDAI scale (R = -0.623, P = 0.002) or number of affected organ systems (R = -0.549, P = 0.008). We also observed reciprocal correlation between DNMT1 protein content in CD4(+) T cells and disease activity scored with SLEDAI scale (R = -0.779, P = 0.001) or number of affected organ systems (R = -0.617, P = 0.019), respectively. Our findings might indicate that LAT, ZAP-70, and DNMT1 protein levels in CD4(+) T cells can be associated with SLE disease.

Trichostatin A down-regulates ZAP-70, LAT and SLP-76 content in Jurkat T cells

We exploited Jurkat leukemia T cell clone E6-1 as a model of Trichostatin A (TSA) effect on cellular levels of ZAP-70, LAT and SLP-76 molecules involved in the signal transduction pathway from T cell receptor to nucleus. Using reverse transcription real-time quantitative PCR and Western blotting analysis we observed that TSA resulted in ZAP-70, LAT and SLP-76 transcript and protein down-regulation in Jurkat leukemia T cells. We also found that TSA reduced half-life of ZAP-70, LAT and SLP-76 mRNAs from 4.8, 3.5, and 4.8 to approximately 2.3, 1.9 and 1.7 h, respectively. Employing the protein biosynthesis inhibitor cycloheximide, we demonstrated the involvement of RNase and/or mRNA stabilization protein in ZAP-70, LAT and SLP-76 mRNAs stabilization. The effect of TSA on ZAP-70, LAT and SLP-76 content in T cells confirms an immunosuppressive effect by TSA, and the usefulness of this histone deacetylase inhibitor in the treatment of autoimmune diseases.

Trichostatin A down-regulate DNA methyltransferase 1 in Jurkat T cells

Histone deacetylase inhibitor Trichostatin A (TSA), alone, is able to activate the transcription of DNA methylation-mediated silenced genes in human cancer cells. Increase in expression and half-life of the DNA methyltransferase DNMT1 has been found in carcinomas of the colon, lung, liver, prostate, and breast cancer. This overexpression of DNMT1 is responsible for hypermethylation of regulatory sequences of many genes involved in tumorigenesis. Using quantitative real-time PCR and Western blot analysis, we found that TSA down-regulate DNMT1 mRNA and protein expression in Jurkat T leukemia cells clone E6-1. We also observed that TSA decreased DNMT1 mRNA stability and reduced this transcript half-life from approximately 7 to 2h. We also found that protein biosynthesis is needed for posttranscriptional regulation of DNMT1 mRNA, which suggests the involvement of an RNase and/or mRNA stabilization protein entity in DNMT1 transcript stabilization. Our findings suggest that TSA not only alters histone acetylation, but also may affect DNA methylation.

Effect of hydralazine on CD3-zeta chain expression in Jurkat T cells

PURPOSE

Deficient CD3-zeta chain expression in T cells of patients with idiopathic SLE is associated with T cell receptor/ /CD3 complex (TCR/CD3)-mediated signaling defect. Hydralazine (HYD) inhibits expression of DNA methyltransferase 1 (DNMT1) and may cause a lupus-like disease in man.

MATERIAL AND METHODS

To explain the HYD effect on intracellular level of CD3-zeta chain in Jurkat T leukemia cells clone E6-1, we employed the flow cytometric analysis.

RESULTS

We observed a dose-dependent increase in cellular content of CD3-zeta chain in Jurkat T cells treated with HYD. Our results suggest that HYD may result in T cells dysfunction different from this observed in idiopathic SLE T cells.

CONCLUSIONS

This difference may partially explain distinct disease course in patients with HYD induced and idiopathic SLE.

Effect of 5-azacytidine and procainamide on CD3-zeta chain expression in Jurkat T cells

It has been observed that decrease of DNA methyltransferase 1 (DNMT1) activity is associated with low content of the CD3-zeta (zeta) chain in T cell receptor (TCR)/CD3 complex of T cells in systemic lupus erythematosus (SLE) patients. The CD3-zeta chain plays a pivotal role in intracellular signal transmission between TCR/CD3 complex and nuclei. The compounds 5'-azacytidine (AZC) and procainamide (PCA) belong to inhibitors of DNMT1, whose low activity correlates with increase in transcription of various genes. Using the reverse-transcription and real-time quantitative PCR (RQ-PCR) analysis, we indicated that AZC and PCA did not profoundly affect on CD3-zeta chain transcription in Jurkat T leukemia cells clone E6-1. However, the flowcytometric analysis revealed that AZC and PCA decreased intracellular contents of CD3-zeta chain in these cells in dose dependent manner. Our results suggest that decrease of DNMT1 activity may alter intracellular signal transmission without effect on transcription level of CD3-zeta chain.

Role of epigenetic DNA alterations in the pathogenesis of systemic lupus erythematosus

Epigenetic alternations in genomic DNA encompass cytosine methylation in cytosine and guanine (CpG) dinucleotide islands, which are usually extended in the promoter and first exon of genes. The DNA methylation is carried out by DNA methyltransferases (DNMT) and it serves as an epigenetic method of gene expression modulation. The epigenetic alternations in genomic DNA have been implicated in the development of malignant and autoimmune diseases. The epigenetic aberration in regulatory DNA sequences may also be responsible for the emergence of changes in the immune system in patients with systemic lupus erythematosus (SLE). The agents 5-azacytidine (azacitidine) and 5-aza-2'-deoxycytidine (decitabine) belong to inhibitors of methyltransferase. These compounds affect the methylation level of promoter sequences and cause phenotypic changes in peripheral blood mononuclear cells (PBMC), which are similar to those observed in PBMC of SLE patients. The lack of methylcytosine in CpG dinucleotides may be responsible for the antigenic properties of microbial DNA. The presence of low-apoptotic methylated DNA fragments has been identified in plasma of SLE patients. These DNA fragments exhibit antigenic properties and may elicit the humoral response responsible for the flare of SLE. The low methylation of CpG residues in the regulatory sequences may also contribute to the elevated expression of human endogenous retroviruses (HERVs) in PBMC of SLE patients. The HERV components exhibit a profound similarity with nuclear antigens and may be responsible for the enhancement of the production of anti-antinuclear antibodies (ANA). Recent advances in the investigation of epigenetic DNA changes have formed the basis of improved understanding of etiopathogenesis of SLE, which may thereby facilitate improvement in therapeutic principles of this disease.

Differences between rats and mice in induction of 4S beta-naphthoflavone-binding protein expression by treatment with beta-naphthoflavone

Sprague-Dawley rats and several inbred strains of mice were compared with respect to the induction of 4S BNF-binding protein expression by treatment with beta-naphthoflavone (BNF), an aryl hydrocarbon receptor (AhR) ligand. Inbred strains of mice chosen for the study encompassed 3 allelic forms of AhR found in Mus musculus so far. As it was reported by us earlier, treating rats with BNF caused a significant induction of BNF-binding protein expression. By contrast, no BNF-binding protein was detected in mice treated with BNF in corn oil as a vehicle or with corn oil itself.

The effect of high molecular weight dextran sulfate on the production of interleukin-8 in monocyte cell culture

It has been demonstrated that high molecular weight dextran sulfate (HMDS) is involved in the activation of immune cells. We have shown that HMDS increases the concentration of interleukin (IL)-8 in the medium of monocyte cell culture, in a dose-dependent fashion, whereas under the same conditions, low molecular weight dextran sulfate (LMDS) does not exhibit any effect on IL-8 biosynthesis. The effect of HMDS on IL-8 production is additive to that of IL-1beta and tumor necrosis factor-a (TNFalpha). Flow cytometric analysis revealed the biosynthesis of IL-8 in monocytes incubated in the presence of the HMDS. We hereby postulate that HMDS induces IL-8 biosynthesis in monocyte cell culture.