Colon cancer therapy: recent developments in nanomedicine to improve the efficacy of conventional chemotherapeutic drugs

The number of patients with colorectal cancer, the third most frequently diagnosed malignancy in the world, has increased markedly over the past 20 years and will continue to increase in the future. Despite recent advances in chemotherapy, currently used anticancer molecules are unable to improve the prognosis of advanced or recurrent colorectal cancer, which remains incurable. The transport of classical drugs by nanoparticles has shown great promise in terms of improving drug distribution and bioavailability, increasing tissue half-life and concentrating anticancer molecules in the tumor mass, providing optimal drug delivery to tumor tissue, and minimizing drug toxicity, including those effects associated with pharmaceutical excipients. In addition, colon cancer targeting may be improved by incorporating ligands for tumor-specific surface receptors. Similarly, nanoparticles may interact with key drug-resistance molecules to prevent a reduction in intracellular drug levels drug. Recently published data have provided convincing pre-clinical evidence regarding the potential of active-targeted nanotherapeutics in colon cancer therapy, although, unfortunately, only a few of these therapies have been translated into early-phase clinical trials. As nanotechnology promises to be a new strategy for improving the prognosis of colon cancer patients, it would be very useful to analyze recent progress in this field of research. This review discusses the current status of nanoparticle-mediated cancer-drug delivery, the challenges restricting its application, and the potential implications of its use in colon cancer therapy.

Regulatory systems in bone marrow for hematopoietic stem/progenitor cells mobilization and homing

Regulation of hematopoietic stem cell release, migration, and homing from the bone marrow (BM) and of the mobilization pathway involves a complex interaction among adhesion molecules, cytokines, proteolytic enzymes, stromal cells, and hematopoietic cells. The identification of new mechanisms that regulate the trafficking of hematopoietic stem/progenitor cells (HSPCs) cells has important implications, not only for hematopoietic transplantation but also for cell therapies in regenerative medicine for patients with acute myocardial infarction, spinal cord injury, and stroke, among others. This paper reviews the regulation mechanisms underlying the homing and mobilization of BM hematopoietic stem/progenitor cells, investigating the following issues: (a) the role of different factors, such as stromal cell derived factor-1 (SDF-1), granulocyte colony-stimulating factor (G-CSF), and vascular cell adhesion molecule-1 (VCAM-1), among other ligands; (b) the stem cell count in peripheral blood and BM and influential factors; (c) the therapeutic utilization of this phenomenon in lesions in different tissues, examining the agents involved in HSPCs mobilization, such as the different forms of G-CSF, plerixafor, and natalizumab; and (d) the effects of this mobilization on BM-derived stem/progenitor cells in clinical trials of patients with different diseases.

How is gene transfection able to improve current chemotherapy? The role of combined therapy in cancer treatment

Despite advances in cancer treatment, a large number of patients eventually develop metastatic disease that is generally incurable. Systemic chemotherapy remains the standard treatment for these patients. Several chemotherapeutic combinations have proven effective in the management of cancer. Paradoxically, although the purpose of polychemotherapy is to improve the prognosis and prolong the survival of patients, it often carries considerable toxicity that causes substantial adverse symptoms. For this reason, a major goal of cancer research is to improve the effectiveness of these cytotoxic agents and reduce their adverse effects. Gene transfer has been proposed as a new strategy to enhance the efficacy of anti-tumor drugs in the treatment of intractable or metastatic cancers. In fact, the association of gene therapy and drugs (combined therapy) has been reported to increase the anti-proliferative effect of classical treatments in lung, bladder, pancreatic, colorectal and breast cancers, among others. Various especially promising therapies have been proposed in this context, including the use of suicide genes, antisense oligonucleotides, ribozymes and RNA interference. In this chapter, we review recent progress in the development of novel anti-cancer strategies that associate cytotoxic agents with gene transfer to enhance their antitumor effect.

Tumour malignancy loss and cell differentiation are associated with induction of gef gene in human melanoma cells

BACKGROUND

Gene therapy is a new method used to induce cancer cell differentiation. Our group previously showed that transfection of the gef gene from Escherichia coli, related to cell-killing functions, may be a novel candidate for cancer gene therapy. Its expression leads to cell cycle arrest unrelated to the triggering of apoptosis in MS-36 melanoma cells.

OBJECTIVES

To determine the basis of the antiproliferative effect of the gef gene in this cell line.

METHODS

Transmission electron microscopy, apoptosis analysis by confocal microscopy, flow cytometry and immunocytochemical analysis were used.

RESULTS

Ultrastructural analysis showed a strikingly different morphology after treatment with dexamethasone and expression of the gef gene, with large accumulations of pigment throughout the cell cytoplasm and presence of melanosomes in different stages of development. High mitochondrial turnover and myeloid bodies, characteristics of neurone cells, were also observed. In addition, both immunocytochemical and indirect immunofluorescence analysis demonstrated a significant decrease in HMB-45, Ki-67 and CD44 antigen expression and an increase in S100 and p53 expression in gef gene-transfected MS-36 melanoma cells that were correlated with the duration of dexamethasone treatment. In the present work, we report that gef gene not only reduces cell proliferation in transfected melanoma MS-36TG cell line but also induces morphological changes clearly indicative of melanoma cell differentiation and a reduction in tumour malignancy.

CONCLUSIONS

These findings support the hypothesis that the gef gene offers a new approach to differentiation therapy in melanoma.

Induction of drug resistance in embryonal rhabdomyosarcoma treated with conventional chemotherapy is associated with HLA class I increase

Effectiveness of conventional cytotoxic treatment of rhabdomyosarcoma (RMS) may be limited by the development of multidrug resistance (MDR) mediated by mdr1 gene. This gene codes for P-glycoprotein (P-gp) which has been related to a immunoregulatory function. Modulation of HLA expression by P-gp has been described in different types of tumor cells including RMS. However, very little is known about biological implications of the P-gp expression in RMS patients treated with conventional chemotherapy. In order to study the problem, we used embryonal RMS tissue samples from treated patients. Our results indicated that positive RMS samples to mdr1 show higher HLA class I expression than those which were negative to mdr1 PCR, what indicates a significant correlation between the expression of both molecules. In addition, we developed two resistant RMS cell lines (A-204-1 and 2) using similar concentrations of actinomycin D as are plasma levels in clinical situation. Both resistant cell lines showed mdr1 expression and an increase of HLA class I expression which was dose-dependent. These results demonstrated that conventional chemotherapy of embryonal RMS is able to induce resistance which can modulate HLA class I expression and suggest that immunological studies of these tumors may be necessary to the design new specific therapeutic strategies.

Non-viral and viral vectors for gene therapy

Human gene therapy can be defined as the delivery of genetic material into a patient's cells with a therapeutic aim. The success or failure of gene therapy depends on the development and efficiency of the transfection of viral and non-viral vectors. Viral vectors typically offer higher transduction efficiency and long-term gene expression, but may be associated with toxicity, immunogenicity, restricted target cell specificity and high cost. Non-viral methods have become widespread because of their relative safety, capacity to transfer large genes, site-specificity and their non-inflammatory, non-toxic and non-infectious properties. However, the clinical usefulness of non-viral methods is limited by their low transfection efficiency and relatively poor transgene expression. In this review, we describe the progress made in the development of gene delivery technology and its possible application in clinical trials.

Cancer gene therapy: strategies and clinical trials

In recent years, great advances have been made in developing novel therapeutic systems based on the introduction of genetic material into damaged cells and designed to correct the error underlying the disease or destroy the pathological cell. One of the main applications of this new approach, known as gene therapy, is the treatment of malignant pathological tumours, in which classic treatments with radiotherapy, chemotherapy and surgery are only palliative. Strategies developed to date include the use of suicide genes, immunity-enhancing genes, apoptosis-inducing genes or genes that inhibit the neovascularization of the tumour, and the blocking of mutated tumour suppressor genes or their restoration in the tumour cell. The effectiveness shown in cell culture and animal experiments and some promising results in clinical trials suggest that gene therapy will help to improve the prognosis of cancer patients and may become the treatment of choice.

Modulation of Ki-67 expression and morphological changes induced by gef gene in MCF-7 human breast cancer cells

New therapeutic strategies are required to overcome the limitations of conventional breast cancer treatment. Suicide gene therapy offers a potential approach to this type of tumour, since systems based on the use of prodrugs may present some drawbacks related to toxicity, drug release and bioavailability. The gef gene has cell-killing functions in Escherichia coli and does not depend on the use of a prodrug for its action, making it an attractive target for suicide gene therapy. We created a gef-overexpressing human breast cancer cell line (MCF-7TG) by transfecting the gef gene under the control of a pMAMneo promotor. Dexamethasone-induction of gef gene expression in MCF-7TG cells produced a significant decrease in Ki-67 expression, which is a known proliferation marker. In addition, annexin-V-FITC and propidium iodide assays showed the presence of apoptotic cell death, which was confirmed by scanning electron microscopy. The most significant finding was the presence of "craters" in the cell membrane, as previously described in other apoptotic breast cancer cells. These results demonstrate the ability of the gef gene to down regulate Ki-67 expression and induce apoptosis in a breast cancer cell line, suggesting its potential application as a new gene therapy strategy for this type of tumor.

Contractile Regulatory Proteins Tropomyosin and Troponin-T as Indicators of the Modulatory Role of Retinoic Acid

Retinoic acid (RA), the active metabolite of vitamin A, plays a significant role in regulating cardiac form and function throughout the life of the organism. Both cardiac morphogenesis and myocardial differentiation are affected by alterations in RA homeostasis. In order to test the effect of all-trans RA and 13-cis RA on cardiomyocyte differentiation, we studied the level and the subcellular compartmentalization of alpha-tropomyosin and troponin-T proteins in cultures of chick embryo cardiomyocytes obtained from Hamburger and Hamilton's (HH) stage 22, 32 and 40 embryos. The retinoids increased the levels of alpha-tropomyosin and troponin-T in the cytoplasmic and cytoskeletal fractions of cells at all three stages of development. The greatest increases in alpha-tropomyosin occurred in the cytoplasmic fraction in HH22 cells cultured for 24 h with all-trans RA or 13-cis RA, whereas the greatest increases in troponin-T were found in the cytoplasmic fraction of HH32 cells exposed to retinoids for 24 h. In cultures treated for 48 h with retinoids, the levels of alpha-tropomyosin and troponin-T showed significant increases in the cytoplasmic compartment of cells treated in HH32-with respect to the control values. These findings are further evidence that RA plays a modulating role in the formation and reorganization of sarcomeric proteins during the process of cardiomyocyte maturation.

Modulation of HLA class I expression in multidrug-resistant human rhabdomyosarcoma cells

An abnormal HLA expression has been detected in some tumors including rhabdomyosarcoma (RMS). Classical cytotoxic treatment of these tumors, the most common childhood soft tissue malignancy, may induce multidrug resistance (MDR) associated with the expression of a 170-kDa membrane-associated glycoprotein (P-glycoprotein). In order to analyse the connection between modulation of HLA expression and the development of the MDR phenotype mediated by P-glycoprotein in RMS, we used three resistant RMS cell lines; two of these resistant cell lines (TE.32.7.DAC and RD-DAC) were established by in vitro exposure to actinomycin D, a drug of choice in the treatment of RMS; the resistant RMS- GR cell line was established from an embryonal RMS tumor after polychemotherapy. Our results showed that all the resistant cell lines showed a significant increase in the expression of HLA class I surface antigens in comparison to drug-sensitive cells. Blockade of P-glycoprotein with verapamil led to a decrease in HLA class I expression in RMS resistant cell lines. However, no modulation of HLA class II expression was observed in any of the three analyzed cell lines. These findings support the hypothesis that the development of resistance mediated by mdr 1/P-glycoprotein, directly influences the expression of HLA class I in RMS cells, inducing to upregulation. This effect may be relevant to the application in RMS of immunotherapy against tumor-associated antigens presented by HLA class I molecules.

Inhibition of growth and induction of apoptosis in human breast cancer by transfection of gef gene

The gef gene has cell-killing functions in Escherichia coli. To evaluate the feasibility of using this gene as a new strategy for cancer therapy, we transfected it in MCF-7 cells derived from breast cancer (MCF-7TG). The gef gene was cloned in a pMAMneo vector under the control of a mouse mammary tumour virus promoter, inducible by dexamethasone (Dex), and was transfected with liposomes. After selection and induction, expression of the gef gene was confirmed by reverse transcription-polymerase chain reactions (RT-PCR) and Western blot. Cell viability was determined with a haemocytometre and the sulphorodamine B colorimetric assay, and the cell cycle was studied by propidium iodide (PI) staining. Annexin V-FITC and PI assays were used to evaluate apoptosis, which was confirmed by electron microscopy. In comparison with MCF-7 parental cells and MCF-7 cells transfected with an empty vector, MCF-7TG cells induced with Dex showed a significant decrease in proliferation rate, which was associated with evidence of apoptosis. Morphological findings confirmed apoptosis and showed a typical pattern of mitochondrial dilation. Furthermore, the cell cycle was characterised by premature progression from G(1) to S phase and G(2) delay. Our results show that the gef gene was able to decrease proliferation in a breast cancer cell line, and induce apoptosis. These findings suggest that the gef gene is a potential candidate for tumour therapy.

Modulation of alpha-actin and alpha-actinin proteins in cardiomyocytes by retinoic acid during development

Early heart development is known to be sensitive to retinoid concentrations. Although the influence of retinoids on cardiac morphogenesis has been described previously, the effect of retinoids on cardiomyocyte differentiation during development has not been characterized. We quantified the effects of the retinoic acids all-trans RA and 13-cis RA on alpha-actin and alpha-actinin at the subcellular level in cultures of chick embryo cardiomyocytes obtained from Hamburger and Hamilton's (HH) stage 22, 32 and 40 embryos. The retinoids increased the concentration of alpha-actin and alpha-actinin in the cytoplasmic and cytoskeletal fractions of cells at all three stages of development. The effect was greatest in cardiomyocytes treated for 24 h with all-trans RA and in cells from HH22 embryos. The greatest increases in alpha-actin concentration occurred in the cytoskeletal fraction of HH22 cells cultured for 24 h with all-trans or 13-cis RA, whereas the greatest increases in alpha-actinin were found in the cytoplasmic fraction of HH22 cells exposed to retinoids for 24 h. We conclude that retinoic acid plays a role in the reorganization of the pattern of sarcomeric protein expression during cardiomyocyte differentiation.

Development of chick cardiomyocytes: modulation of intermediate filaments by basic fibroblast and platelet-derived growth factors

Recent studies suggest that peptide growth factors play a functional role in cardiac muscle. To test whether embryonic cardiac muscle is a target for regulation by basic fibroblast growth factor and platelet-derived growth factor, we analyzed the effects of these peptides on the expression of the intermediate filaments desmin and vimentin at the subcellular level during development. Sodium dodecyl sulfate-gel electrophoresis, immunoblotting and fluorescence-activated cell sorting analysis were used to study the effect of basic fibroblast growth factor and platelet-derived growth factor on cultures of chick cardiomyocytes during development. Cytoplasmic and cytoskeletal concentrations of desmin and vimentin were dependent on the stage of embryonic development and on the type of growth factor added to the culture. The most significant finding was the increase in desmin expression in the cytoplasmic and cytoskeletal compartments after treatment with basic fibroblast growth factor (10 ng/ml) of chick heart cells at Hamburger and Hamilton stage 19. In more mature stages, basic fibroblast growth factor did not modify the levels of desmin expression. However, this factor led to a progressive deceleration in the rate of increase in vimentin expression. Platelet-derived growth factor increased vimentin expression in all stages studied, the greatest increases appearing in early stages of heart development. Our findings support the hypothesis that basic fibroblast growth factor plays a role in cardiomyocyte differentiation during the early stages of development, whereas platelet-derived growth factor has a dedifferentiating effect.

Modulation of myogenic differentiation in a human rhabdomyosarcoma cell line by a new derivative of 5-fluorouracil (QF-3602)

The in vitro study of mechanisms involved in drug-induced maturation has made it possible to use differentiation-based therapy in clinical practice. The goal of this new therapy is the development of specific agents to induce cancer cells to stop proliferating and express characteristics of normal cells. Recently, by structural modifications of 5-fluorouracil (5-FU), we synthesized a new pyrimidine acyclonucleoside-like compound, 1-¿[3-(3-chloro-2-hydroxypropoxy)-1-methoxy]propyl¿-5-fluorouracil (QF-3602), which showed in rhabdomyosarcoma cells a low toxicity and time-dependent growth inhibition. In this work, we compared the degree of myogenic differentiation of RD rhabdomyosarcoma (RMS) cells after treatment with QF-3602 and 5-FU. Scanning and transmission electron microscopy (SEM and TEM) and immunocytochemical analyses showed that QF-3602 induced the appearance of myofilaments along the myotube-like giant RD cells, an increase in fibronectin and a decrease in vimentin expression. In contrast, only minor changes were observed with 5-FU. Moreover, polymerase chain reaction (PCR) analyses showed that QF-3602 did not induce overexpression of the mdr 1 gene, a resistance mechanism that frequently appears in classical cytotoxic therapy in these tumors. Compounds obtained by structural modifications of 5-FU may be useful in differentiation therapy as a new approach to the treatment of RMS.

Multidrug resistance phenotype in the RMS-GR human rhabdomyosarcoma cell line obtained after polychemotherapy

Classical cytotoxic treatment of rhabdomyosarcoma (RMS), the most common soft tissue malignacy in children, is often accompanied by significant morbidity and poor response. Chemotherapy may induce multidrug resistance (MDR) associated with the expression of P-glycoprotein, a drug efflux pump which modifies the sensitivity of tumoral cells to drugs. To analyze MDR in RMS we used the RMS-GR cell line, obtained from an embryonal rhabdomyosarcoma treated in vivo with polychemotherapy. The RMS-GR cells showed cross-resistance to vincristine, doxorubicin and actinomycin D, the drugs of choice in the conventional treatment of RMS. Polymerase chain reaction (PCR) analysis showed that these RMS cells overexpressed mdr1/P-glycoprotein. The pattern of resistance and the level of P-glycoprotein expression were similar to those found in the resistant RMS TE.32.7.DAC cell line obtained in vitro. Southern blot analysis showed that mdr1 overexpression was not due to amplification of the gene. Our results showed that the in vivo treatment of embryonal RMS may induce an MDR phenotype mediated by mdr1/P-glycoprotein in RMS cells.

GR-891: a novel 5-fluorouracil acyclonucleoside prodrug for differentiation therapy in rhabdomyosarcoma cells

Differentiation therapy provides an alternative treatment of cancer that overcomes the undesirable effects of classical chemotherapy, i.e. cytotoxicity and resistance to drugs. This new approach to cancer therapy focuses on the development of specific agents designed to selectively engage the process of terminal differentiation, leading to the elimination of tumorigenic cells and recovery of normal cell homeostasis. A series of new anti-cancer pyrimidine acyclonucleoside-like compounds were designed and synthesized by structural modifications of 5-fluorouracil, a drug which causes considerable cell toxicity and morbidity, and we evaluated their applicability for differentiation therapy in human rhabdomyosarcoma cells. We tested the pyrimidine derivative GR-891, (RS)-1-[[3-(2-hydroxyethoxy)-1-isopropoxy]propyl]-5-fluorouracil, an active drug which shows low toxicity in vivo and releases acrolein which is an aldehyde with anti-tumour activity. Both GR-891 and 5-fluorouracil caused time- and dose-dependent growth inhibition in vitro; however, GR-891 showed no cytotoxicity at low doses (22.5 micromol l(-1) and 45 micromol l(-1)) and induced terminal myogenic differentiation in RD cells (a rhabdomyosarcoma cell line) treated for 6 days. Changes in morphological features and in protein organization indicated re-entry in the pathway of muscular maturation. Moreover, GR-891 increased adhesion capability mediated by the expression of fibronectin, and did not induce overexpression of P-glycoprotein, the mdr1 gene product, implicated in multidrug resistance. New acyclonucleoside-like compounds such as GR-891 have important potential advantages over 5-fluorouracil because of their lower toxicity and their ability to induce myogenic differentiation in rhabdomyosarcoma cells. Our results suggest that this drug may be useful for differentiation therapy in this type of tumour.

Optimization of the tyrosinase mRNA probe to detect circulating melanocytes with reverse transcription and polymerase chain reaction

It was recently suggested that reverse transcription polymerase chain reaction (RT-PCR)-based detection of tyrosinase messenger RNA (mRNA) in peripheral blood is useful in the early detection of circulating tumor cells, since tyrosinase is thought to be a melanocyte-specific marker. However, the sensitivity of detection of these cells in circulation is controversial, some authors reporting 0% effectiveness, others obtaining 100% efficacy. We developed a modification of a technique to process blood samples to detect tyrosinase mRNA, and tested the method with 50 samples from as many patients with histologically confirmed malignant melanoma in different stages. Whole blood was processed by discarding the plasma and extracting RNA from density gradient-isolated peripheral blood lymphocytes. The RNA samples were tested with a sensitive nested primer RT-PCR assay. Sensitivity was tested using RNA extracted from SK-mel-1 human melanoma cells diluted serially with peripheral blood obtained from healthy control subjects. A lymph node from a patient with confirmed disseminated melanoma served as the positive control. Our technique was able to detect tyrosinase mRNA in samples from the 37 patients with progressive metastatic melanoma. The test detected tyrosinase mRNA from both the melanoma cell line and the positive lymph node. Our method to extract RNA from whole blood improves the specificity and sensitivity of tyrosinase mRNA detection by RT-PCR. The test should be of use in determining the prognosis of patients with melanoma, and in deciding when to initiate early treatment in patients with malignant melanoma.

Therapeutic differentiation in a human rhabdomyosarcoma cell line selected for resistance to actinomycin D

Classical cytotoxic treatment of rhabdomyosarcoma (RMS) is accompanied often by significant morbidity and poor response. The use of cytotoxic agents may induce a multidrug resistance phenotype, which plays an important role in the sensitivity of tumoral cells to drugs. Using actinomycin D, a drug of choice in the treatment of RMS, we induced resistance in the TE.32.7 human RMS cell line. The TE.32.7-DAC-resistant cell line exhibited cross-resistance to vincristine and doxorubicin and showed mdr1/P-glycoprotein over-expression, suggesting that this mechanism was involved in the reduction in intracellular drug concentration and may be responsible for the failure of treatment of RMS with classical cycles of cytotoxics. Furthermore, this resistant cell line showed increased expression of the muscle differentiation markers desmin and alpha-actinin and ultrastructural changes which clearly indicated myogenic differentiation. Our findings suggest that, although this tumor is probably arrested along the normal myogenic pathway to maturation, induction of cell differentiation with anti-neoplastic drugs may be an alternative therapeutic approach. However, the failure of TE.32.7-DAC cells to completely re-enter the program of myogenic differentiation supports the hypothesis that multidrug resistance is a major obstacle in differentiation therapy for RMS.

Clinical significance of antiheart antibodies after myocardial infarction

We used one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis of myocardial proteins followed by Western blotting to study the formation of antiheart antibodies during three months after myocardial infarction and the relationship between the appearance of antibodies and clinical and laboratory findings. Fifty-four percent of the 66 patients with infarction had different types of antiheart antibodies. The autoantibodies detected most frequently were against 35 and 42 kDa cardiac proteins. Immunoblottings with purified proteins showed that these autoantibodies reacted against myocardial tropomyosin and actin, which have been detected after acute myocardial infarction and can have immunogenetic activity through a humoral immune response. However, only the presence of autoantibody against myocardial tropomyosin correlated significantly with the presence of clinical and laboratory findings. Our results suggest that autoantibody against myocardial tropomyosin may play an immunopathogenic role in the development of symptoms in these patients.

Actinomycin D treatment leads to differentiation and inhibits proliferation in rhabdomyosarcoma cells

Human embryonal cell line RD is derived from rhabdomyosarcoma, a tumor of childhood that arises from rhabdomyoblasts probably arrested somewhere along their pathway to maturation. Because actinomycin D is a drug of choice in the treatment of rhabdomyosarcomas, and because it has been used to induce differentiation as an alternative therapy for myeloproliferative syndromes, we treated RD cells with different concentrations of actinomycin D and evaluated the effects on growth and differentiation. Actinomycin D treatment in vitro caused time- and dose-dependent growth inhibition. Interestingly, RD cells treated with low doses (2.85 and 5.7 nmol/L) of actinomycin D for 6 days showed morphologic and phenotypic differentiation, with increased expression of desmin, alpha-actinin, and tropomyosin. However, treatment with 11.4 nmol/L actinomycin D strongly inhibited growth and had cytotoxic effects that prevented the cells from attaining myogenic differentiation. We conclude that exposure of this human embryonal rhabdomyosarcoma cell line to low concentrations of actinomycin D released the neoplastic cells from their blockade, allowing them to recover normal myogenic development. We suggest a potential role for differentiation therapy in the treatment of rhabdomyosarcomas.

Low sample volume causes differentiation in human rhabdomyosarcoma cell line RD subjected to electroporation

Gene transfection has been accomplished with a variety of techniques such as DEAE dextran, calcium phosphate coprecipitation, protoplast fusion, liposomes, microinjection and recombinant bacteriophages. However, transfection by electroporation, consisting of the reversible permeabilization of cell membranes after exposure to a pulsed electric field, has been shown to be the most rapid, simple and efficient method for the stable incorporation of genes in different cell lines. We studied rhabdomyosarcoma cells subjected to electroporation in two different vol. [400 microliters (group 1) and 150 microliters (group 2] of 140 mM NaCl/15 mM Hepes buffer, pH 7.2) and evaluated the effects of electroporation volume on growth and differentiation. Low sample volumes induced a terminal process of morphological and ultrastructural myogenic differentiation in rhabdomyosarcoma cells, which concluded with cell death. Our results suggest that in electroporation low sample vol. of rhabdomyosarcoma cells induced morphological and phenotypic differentiation, with increased expression of desmin, alpha-actinin and tropomyosin.

Inverse expression of mdr 1 and c-myc genes in a rhabdomyosarcoma cell line resistant to actinomycin d

Cytotoxic agents used in cancer therapy may induce differentiation in tumour cells with no proliferative potential. However, chemotherapy can also induce multidrug resistance, a formidable obstacle to the successful treatment of tumours. Both events were recently shown to occur in a rhabdomyosarcoma cell line (RD-DAC) resistant to actinomycin D, a drug of choice in the treatment of these tumours. To analyse this connection, cell line RD cultures were investigated with progressive concentrations of actinomycin D and it was shown that a minimum dose (1.2 x 10(-6) mM) of the drug was necessary to increase mdr 1 mRNA in RD-DAC. The mechanism of mdr 1 overexpression was an increase in the number of copies of the mdr 1 gene, although the mRNA levels were not correlated with mdr 1 amplification. Drug resistance mediated by mdr 1 overexpression coincided with the development of myogenic differentiation in RD-DAC and with a decrease in c-myc mRNA levels, whereas levels of N-myc mRNA showed no modulation. These findings suggest that factors implicated in cell proliferation and differentiation, such as c-myc, may be responsible for the control of genes related to the development of multidrug resistance in rhabdomyosarcomas. Modulation of these factors may determine the sensitivity of rhabdomyosarcoma cells to drugs and may play an important role in triggering the differentiation programme found in these resistant rhabdomyosarcoma cells.

Detection of circulating alpha-actinin in non-insulin-dependent diabetics with autonomic dysfunction

The presence of cardiac proteins in serum has been related to ischemic heart diseases such as acute myocardial infarction and angina pectoris, which are more frequent in non-insulin-dependent diabetic patients. Silent myocardial ischemia, which is also more frequent in these patients, occurs in association with autonomic dysfunction. We used Western blot analysis to search the myocardial protein alpha-actinin in sera from non-insulin-dependent diabetic patients with or without autonomic dysfunction. Of the 24 diabetic patients with neuropathy, 18 were positive for circulating alpha-actinin; this protein was found in only 1 of the 22 diabetic patients without neuropathy. Our results showed a significant correlation between non-insulin-dependent diabetic patients with neuropathy and detectable circulating alpha-actinin in serum, and suggest that the determination by immunoblotting of serum alpha-actinin in these patients may be an effective method to detect myocardial cell impairment, and to identify diabetic patients that may need special consideration.

Low concentrations of actinomycin D potentially cause therapeutic differentiation in human rhabdomyosarcoma cell line RD

Neoplastic transformation may be an alteration in the process of cell maturation that leads to an infinite capacity for proliferation. Because the cytodestruction caused by most drugs available for cancer chemotherapy is often accompanied by significant morbidity and poor response, the induction of differentiation has been proposed as an alternative approach to conventional anticancer therapy. We used human rhabdomyosarcoma cell line RD to analyze the differentiation process induced by actinomycin D, a drug of choice in the conventional treatment of rhabdomyosarcomas. Low concentrations of actinomycin D induced a terminal process of morphological and ultrastructural myogenic differentiation in rhabdomyosarcoma cells, which concluded with cell death. However, this potential therapeutic effect cannot be considered complete because of the presence of tumoral cells that are heterogeneous with respect to actinomycin D chemosensitivity. This heterogeneity led to the appearance of foci of resistant cells which, despite their greater degree of differentiation in comparison with the parental cell line, escaped from terminal myogenic differentiation. This subgroup of tumoral cells may be responsible for the failure of cytotoxic treatment.

Modulation of cardiac intermediate filament proteins in the chick heart by fibric acid derivatives

The effects of different fibrates (bezafibrate, fenofibrate and gemfibrozil) on intermediate filaments were studied in cultured chick embryo heart cells after treatment for 6 or 24 h. Treatment led to alterations in total protein levels, as well as changes in protein levels, in the cytoplasmic and cytoskeletal fractions of cultured cells. Desmin was increased in the cytoskeletal fraction of all cultures after 6 h of treatment regardless of the drug tested, whereas vimentin was decreased in the cytoskeletal fraction only in cells treated with fenofibrate. These findings suggest that the alterations caused by fibrates in desmin and vimentin protein content may be related with the secondary effects that these drugs have on the cardiovascular system in patients treated with fibrates.

Basic fibroblast and platelet-derived growth factors as modulators of actin and alpha-actinin in chick myocardiocytes during development

To test whether cardiac muscle is a target for regulation by peptide growth factors, we analyzed the effects of two growth factors on actin and alpha-actinin expression at the subcellular level. Sodium dodecyl sulfate-gel electrophoresis, immunoblotting, and fluorescense-activated cell sorter analysis were used to quantify the effects of basic fibroblast growth factor and platelet-derived growth factor on cultures of chick myocardiocytes during development. Cytoplasmic and cytoskeletal concentrations of actin and alpha-actinin were dependent on the stage of embryonic development and on the type of growth factor added to the culture. The most significant finding was the increase in actin and alpha-actinin expression in the cytoplasmic compartment after treatment with basic fibroblast growth factor of chick heart cells at Hamburger and Hamilton's stage 19. At stage 39, basic fibroblast growth factor induced less marked changes in the accumulation of actin and alpha-actinin. Platelet-derived growth factor decreased alpha-actinin expression slightly in the cytoskeletal compartment in more mature stages of heart development. Our findings support the hypothesis that basic fibroblast growth factor plays a role in cardiomyocyte differentiation during the early stages of development.

Circulating alpha-actin in non-insulin-dependent diabetics with autonomic dysfunction

Silent myocardial ischemia in non-insulin-dependent diabetic patients occurs frequently in association with autonomic dysfunction, suggesting that diabetic neuropathy may be involved in the development of this disorder. Repeated episodes of silent myocardial ischemia can induce myocardial necrosis. Recently, actin was detected with Western blotting in the serum of patients with acute myocardial infarction and angina pectoris. We found that a large proportion of non-insulin-dependent diabetic patients with neuropathy also have detectable circulating concentrations of alpha-actin, and therefore suggest that the determination by immunoblotting of serum alpha-actin in such patients is an effective method to detect myocardial cell suffering and to identify patients that may need special consideration.

Swine hearts: quantitative anatomy of the right ventricle

The right ventricle was studied in 75 anatomically normal swine hearts, using, in all, nine geometric and volumetric parameters: ventricular-wall thickness, length of the right-ventricular inflow and outflow tracts, and volume of the right-ventricular inflow and outflow tracts. The data for these parameters were compared with previously published patterns for human hearts and volumetric data were compared with patterns of normality found in human hearts. As in the human heart, the ventricular inflow tract in swine hearts was significantly shorter than the outflow tract (P < 0.0001).

Differentiation of a human rhabdomyosarcoma cell line after antineoplastic drug treatment

The feasibility of treating solid tumours with differentiation therapy using antineoplastic drugs is currently being investigated, but the emergence of multidrug resistance remains the major limitation to this therapeutic approach. A rhabdomyosarcoma cell line resistant to actinomycin D (RD-DAC) has been used as an in vitro model to investigate, with light and electron microscopy, the degree of differentiation in multidrug-resistant cells. The parental cell line (RD), derived from a human embryonic-type rhabdomyosarcoma, is undifferentiated, with no evidence of specific ultrastructural markers. Examination of resistant cells by transmission electron microscopy revealed myofilaments arranged parallel to the long axis of the cell, which was considered clear evidence of myogenic differentiation. These observations suggest that actinomycin D, the drug of choice in the treatment of rhabdomyosarcoma, induces differentiation in the cell line RD. It is postulated that multidrug resistance can interfere with cellular differentiation.

Modulation of contractile protein troponin-T in chick myocardial cells by catecholamines during development

In the present study we quantified the contractile protein troponin-T at the cellular and subcellular level in chick embryo cardiomyocytes to investigate the modulation of cardiac development by catecholamines. We analyzed the effects of these drugs on cultures of chick cardiomyocytes obtained from Hamburger and Hamilton's (HH) stage 21, HH stage 29 and HH stage 40 embryos; cardiomyocytes are considered to be mature at HH stage 40. We analyzed the modifications these drugs induced in the transcription of the gene for chick cardiac troponin-T. Sodium dodecyl sulfate-gel electrophoresis and immunobloting showed that cytoplasmic and cytoskeletal concentrations of troponin-T are dependent on the stage of embryonic development analyzed, and on the type of catecholamine added to the culture. The most significant finding was the increase in troponin-T mRNA in the chick heart at HH stage 40, accompanied by an increase in the increase in the expression of this protein in the cytoskeletal compartment after treatment with norepinephrine. At HH stage 21, norepinephrine induced less marked changes in the accumulation of troponin-T in comparison with untreated cardiomyocytes.

Creatine kinase isoenzymes as markers of differentiation in rhabdomyosarcoma cells in culture

Rhabdomyosarcomas have been classified on the basis of their degree of differentiation, a feature closely related with their response to chemotherapy. We recently reported the role of creatine kinase isoenzymes as tumoral markers in the diagnosis of rhabdomyosarcoma. The present study was designed to determine whether these isoenzymes are also good markers of the degree of differentiation of these neoplasm. Dimethyl sulfoxide, a well-known differentiating agent, was used to induce myogenic differentiation. This agent increased CK-MM and/or CK-MB fractions, and decreased CK-BB isoenzyme in rhabdomyosarcoma cell lines. The variable behavior of MCK-1 macromolecule was unrelated to the degree of differentiation. Our findings suggest that CK-MM, CK-MB and CK-BB isoenzymes are good markers of the degree of differentiation in rhabdomyosarcomas and could be used as specific markers of prognostic and diagnostic value.

Modulation of contractile protein troponin-T in chick myocardial cells by basic fibroblast growth factor and platelet-derived growth factor during development

We quantified the effect of basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) on the contractile protein troponin-T (TnT) at the cellular and subcellular level in cultures of chick embryo cardiomyocytes obtained from Hamburger and Hamilton's (HH) stage 19, 29, and 39 embryos. Because expression of thin-filament molecules is considered a good marker of differentiation in muscle cell cultures, we analyzed the modifications these growth factors induced in the transcription of the gene for chick cardiac TnT. Sodium dodecyl sulfate-polyacrylamate gel electrophoresis (SDS-PAGE) and immunoblotting showed that cytoplasmic and cytoskeletal concentrations of TnT are dependent on the stage of embryonic development analyzed and on the type of growth factors added to the culture. The most significant finding was the increase in TnT expression in the cytoplasmic compartment (p < 0.001), accompanied by a slight increase in TnT mRNA, after treatment with bFGF of chick heart cells obtained at HH stage 19. At HH stage 39, bFGF induced less marked changes in the accumulation of TnT in comparison with untreated cardiomyocytes. Our findings support the hypothesis that bFGF plays a role in cardiomyocyte differentiation during early stages of development.

Production and characterization of a new monoclonal antibody, GR-ICOR-2, recognizing sarcomeric actin: analysis of the expression in the developing chick heart

We produced and characterized a specific monoclonal antibody (mAB) designated GR-ICOR-2. This mAb recognizes sarcomeric actin molecules (43 kDa) and was used in an immunohistochemical analysis of staining patterns in Hamburger and Hamilton's stages 18, 22 and 25 (HH 18, 22 and 25) embryonic chick hearts. Staining showed a mainly cytoplasmic distrubition in three regions: the atrioventricular (AV) canal cushion tissue, the primitive ventricle, and conal crests. In addition, this mAb-cross-reacted with rabbit and human cardiac and skeletal muscle tissue; but not with smooth muscle tissue.

Influence of dimethyl sulphoxide on intermediate filament proteins in human rhabdomyosarcoma cell lines: modulation at subcellular level

The effects of dimethyl sulphoxide have been investigated on differentiation in human rhabdomyosarcoma cell lines obtained from typically malignant, poorly differentiated tumours. The expression of cell differentiation marker proteins (desmin and vimentin) was assessed in cell lines A-204, A-673 and RD, and the modifications in expression after 3, 8 and 24 h of induction with 1.25% dimethyl sulphoxide were recorded. Protein expression in both the cytoplasm and cytoskeleton was significantly altered by treatments lasting 8 and 24 h, the most noteworthy changes being increased desmin and decreased vimentin expression. The results clearly indicate that dimethyl sulphoxide induced changes typical of differentiation in rhabdomyosarcoma cell lines A-673 and RD; less marked changes were observed in line A-204.

Actinomycin D causes multidrug resistance and differentiation in a human rhabdomyosarcoma cell line

The emergence of drug-resistant tumor cells remains a major problem in cancer chemotherapy. Resistance to multiple unrelated antineoplastic drugs may be related, in part, to expression of the P-glycoprotein. The cell line RD, derived from an embryonic rhabdomyosarcoma tumor, was used as an in vitro model to examine the development of drug resistance. A cell line resistant to actinomycin D (RD-DAC) was developed by growing RD in increasing concentrations of the drug. The ID50 (concentration of drug needed to induce a 50% reduction in cell growth) of the resultant line to actinomycin D was more than 15 times that of the parental line. The resistant line was cross-resistant to vincristine and doxorubicin. Resistance to actinomycin D resulted in increased P-glycoprotein expression, which was associated with a change in desmin and vimentin expression. These results suggest that exposure to chemotherapeutic drugs can induce not only classical multidrug resistance, but also a process of cellular differentiation in rhabdomyosarcoma cells.

Modulation of contractile proteins in embryonic and fetal chick cardiac cells by phorbol ester, gamma-interferon, 5-azacytidine and diacylglycerols

We studied changes in the concentration of tropomyosin, actin, desmin and vimentin in cultured myocardiocytes from Hamburger and Hamilton's stages 29 and 39 chick embryos (HH29 and HH39) (1), treated with 12-o-tetradecanoyl-phorbol-13-acetate (TPA), 5-azacytidine (AZA), gamma interferon (INF) and diacylglycerols (DAG). In embryonic myocardiocytes at HH29, the first three agents modified the intracellular distribution of the thin filament proteins tropomyosin and actin, increasing their cytoplasmic concentration and decreasing their cytoskeletal concentration. The concentration of the intermediate filament proteins desmin and vimentin increased in both subcellular fractions after treatment with these drugs. In fetal myocardiocytes at HH39, total protein content decreased after treatment with these drugs. Cytoplasmic and cytoskeletal concentrations of actin and tropomyosin decreased to different degrees after treatment with TPA, AZA or DAG in HH39 myocardiocytes. TPA, AZA and DAG decreased desmin in the cytoplasmic and cytoskeletal fractions. These findings suggest that the drugs tested alter the normal protein composition in cultured myocardiocytes, and have different effects depending on the developmental stage in which the embryo is treated.

Expression of epidermal growth factor receptor in chick embryo myocardiocytes: relation with desmin expression during cardiac development

The epidermal growth factor receptor is related with processes of cell replication and differentiation. We used the intermediate filament protein desmin as a marker to study the relation between muscle cell differentiation and modifications in the expression of this receptor during heart development in the chick embryo. Epidermal growth factor receptor was expressed as early as Hamburger and Hamilton's stage 17, when myocardiocytes are still poorly differentiated and desmin-negative. Expression became steadily weaker as the heart matured, and decreased after Hamburger and Hamilton's stage 25, a key stage in heart maturation characterized by a sharp increase in desmin expression. Our findings suggest that in the chick embryo, the expression of epidermal growth factor receptor becomes steadily weaker as myocardiocyte differentiation progresses.

[The swine heart: the papillo-tendino-valvular system of the right ventricle]

The right ventricle was studied in 75 anatomically normal swine hearts. Nine parameters in the papillo-tendino valvular system and three corresponding to the tricuspid orifice, pulmonary orifice and length of the inflow tract were measured. Correlations were established between the parameters and heart weight in grams, between the different parameters themselves, and between heart weight and body weight. The results were compared with similar data from human hearts, and were considered of use to researchers planning to use the swine heart as an experimental model to study congenital or induced heart diseases, or as a reference for the clinical interpretation of spontaneous cardiac, anomalies in swine.

Actin, tropomyosin and alpha-actinin as markers of differentiation in human rhabdomyosarcoma cell lines induced with dimethyl sulfoxide

Most rhabdomyosarcomas are poorly differentiated malignant tumors. Dimethyl sulfoxide has been shown to modulate cell differentiation in cultured human cells. We induced differentiation in human rhabdomyosarcoma cell lines A-673, RD and A-204 with 1.25% dimethyl sulfoxide, and used desmin, the protein most frequently used as a marker of muscle cell differentiation, to trace this process. As alternative markers of the degree of differentiation, we quantified the expression of the proteins actin, tropomyosin and alpha-actinin in these cell lines, and followed the changes in expression of these proteins after induction for 8, 12, 24, 48 and 72 hrs. In the process of differentiation, protein expression in both the cytoplasm and cytoskeleton was significantly increased by treatments lasting 12 hrs. (alpha-actinin) and 24 hrs. (actin). On the basis of our results, alpha-actinin can be considered as an earlier marker of differentiation than actin in human rhabdomyosarcoma cell lines. However, the earliest indication of differentiation was a modification in desmin expression (8 hrs.). Because changes in tropomyosin expression were less marked, we consider this protein as a poor marker of rhabdomyosarcoma cell differentiation.

Production of a new monoclonal antibody recognizing alpha-actinin: analysis of the changes in subcellular expression in the developing chick heart

A new monoclonal antibody that recognizes alpha-actinin in cardiac muscle cells was used in a quantitative study (fluorescence activated cell sorting and polyacrylamide gel electrophoresis) of the expression of this protein during chick embryo development, to determine the changes in cytoplasmic and cytoskeletal compartments. alpha-Actinin expression was weak in early stages of development (Hamburger and Hamilton stage 18) and increased steadily until Hamburger Hamilton stage 40. In all stages, the protein was more abundant in the cytoplasmic compartment. The monoclonal antibody cross-reacted with alpha-actinin in chicken smooth and striated muscle cells and also showed a faint cross-reaction with human cardiac muscle alpha-actinin.

Circulating alpha-actin in angina pectoris

We used Western blot, a highly sensitive technique that detects amounts of protein as low as 0.1 to 1.0 ng, to investigate the possible presence in the blood stream of the contractile protein alpha-actin in 29 patients diagnosed with angina pectoris (Braunwald's classification). Circulating protein was identified with a monoclonal antibody specific for cardiac alpha-actin. Of the 20 control samples of blood, the immunoblot results were negative for alpha-actin in 19. Of the 30 patients with skeletal muscle damage caused by surgery, 27 were negative for circulating alpha-actin. Of the 29 patients with angina pectoris, circulating alpha-actin was found in 19 as a 43 kDa band in immunoblots. Of the four patients with anterior acute myocardial infarction, mean concentration of circulating alpha-actin was 58 mg/l. Among the patients with angina pectoris, the highest circulating concentrations (mean 40 mg/l) was found in those with prolonged angina (class III B, according to Braunwald's classification). In the entire group of individuals with angina pectoris alpha-actin was detectable in serum for up to 175 h after the onset of pain, and showed two peaks, one at 1 h (112 mg/l) and one at 50 h (82 mg/l) after the onset of pain. These findings reinforce the notion that unstable angina should be considered a serious condition.

Changes in subcellular accumulation of contractile proteins in myocardiocyte cultures: effects of fibric acid derivatives

We analyzed the influence of 6 and 24 h of treatment with the fibric acid derivatives bezafibrate (10 micrograms/ml), gemfibrozil (23 micrograms/ml), and fenofibrate (30 micrograms/ml) on alpha-actinin, troponin-T, and tropomyosin proteins in the cytoplasmic and cytoskeletal fractions of cultured chick myocardiocytes. The findings with sodium dodecyl sulfate-gel electrophoresis and immunoblotting showed that all three drugs modified cellular and subcellular protein levels in different ways: bezafibrate and fenofibrate produced the most significant alterations in both fractions, modifying alpha-actinin, troponin T, and tropomyosin compartmentalization in myocardiocytes, whereas gemfibrozil altered these proteins less notably. Given the role of these proteins in heart muscle contraction, fibric acid derivative-induced changes may be related with the secondary effects of these drugs on heart rhythmicity.