Growth Inhibition Of Malignant Cells Research Articles

Understanding the prophylactic, chemo preventive, and pharmacotherapeutic perspectives of various dietary foods in breast cancer

Currently, one of the most challenging diseases to tis breast cancer. Hormone therapy, surgery, chemotherapy, and radiation have all been used to treat breast cancer for a long time, but they are become eating less and less successful due to serious side effects and rising drug resistance. Numerous dietary foods have been linked to altered cancer genesis and progression pathways, decreased aggressiveness, and growth inhibition of malignant cells. These dietary foods may be advantageous compared to produce medications since they exhibit lower toxicity and negative effects in various investigations. The promises made by dietary foods for breast cancer treatment by focusing on several pathophysiological cascades involved in the onset and progression of breast cancer and their capacity to simultaneously stop metastatic and growth progression. Some of the extensively researched numerous dietary foods that specifically target certain breast cancer pathways and express any of the three attributes are mentioned in article.

Overexpression of MiR-138 Inhibits Cell Growth and Induces Caspase-mediated Apoptosis in Acute Promyelocytic Leukemia Cell Line.

Dysregulated expression of miRNAs can play a vital role in pathogenesis of leukemia. The shortened telomere length, and elevated telomerase activity in acute promyelocytic leukemia cells are mainly indicative of extensive proliferative activity. This study aimed to investigate the effect of overexpression of miR-138 on telomerase activity, and cell proliferation of acute promyelocytic leukemia NB4 cells. MiR-138 was overexpressed in NB4 cells using GFP hsa-miR-138-expressing lentiviruses. hTERT mRNA and protein expression levels were assessed by qRT-PCR and western blot analysis. For evaluation of apoptosis, annexin-V staining and activation of caspases were assessed using flow cytometry and western blot analysis, respectively. Our data demonstrate that overexpression of miR-138 attenuated the hTERT mRNA and protein expression levels. In addition, cell growth was inhibited, and malignant cells underwent caspase mediated-apoptosis in response to miR-138 overexpression. These findings suggest that loss of miR-138 expression may be associated with increased telomerase activity in NB4 cells. Therefore, strategies for up-regulation of miR-138 may result in inhibition of malignant cell growth, and provide a promising therapeutic approach for acute promyelocytic leukemia.

Optimising Selenium for Modulation of Cancer Treatments.

Selenium is an essential trace element involved in many biological processes that are mediated through, at least, 25 selenoproteins expressed in humans. Extensive study of selenium compounds has demonstrated growth inhibition of malignant cells in a vast array of experimental models. Moreover combining selenium with conventional cancer therapy has yielded promising results in both preclinical studies and a cohort of human trials. The aim of this review is to highlight the current research evaluating the role of selenium compounds in combination with chemotherapy and radiation. Pharmacodymanic mechanisms responsible for the differential effects of the commonly studied compounds on healthy and malignant cells are presented and the pertinent in vitro and in vivo data summarised. The clinical utility of this approach is discussed both in terms of anti-tumour efficacy and toxicity prevention. Finally a case is made for novel trial designs to facilitate rapid progression into pivotal studies.

Cyclic Changes in the Expression of p57kip2 in Human Endometrium and its Regulation by Steroid Hormones in Endometrial Stromal Cells In Vitro

We investigated the expressions of p57(kip2) and p27(kip) and its regulation by steroids in the normal and abnormal human endometrium. Endometrial p27(kip1) and p57(kip2) messenger RNA (mRNA) were markedly increased in the secretory phase. P57(kip2) protein was absent in proliferative phase but appeared in glandular epithelium together with early- to mid-secretory phase stromal cells. During the late secretory phase, strong P57(kip2) protein immunoreactivity was found in the stromal cells. In both endometrial hyperplasia and cancer, the expression of P57(kip2) protein was low. In cultured human endometrial stromal cells (ESCs), p27(kip1) mRNA levels were increased together with the decidual marker prolactin (prl), following treatment with 17β-estradiol (E2) and progesterone (P4). At 1 nmol/L, the glucocorticoid receptor (GR) agonist dexamethasone (DEX) induced prl, p57(kip2) , and p27(kip1) mRNA in ESCs. Taken together, upregulation of p57(kip2) may play an important role in the decidual differentiation by P4 and growth inhibition of malignant cells in human endometrium.

Single-Agent Lenalidomide in the Treatment of Previously Untreated Chronic Lymphocytic Leukemia

Lenalidomide is an oral immunomodulatory drug with multiple effects on the immune system and tumor cell microenvironment leading to inhibition of malignant cell growth. Based on encouraging reports of lenalidomide in relapsed and refractory chronic lymphocytic leukemia (CLL), we investigated the first-line use of single-agent lenalidomide in CLL. Using a starting dose of lenalidomide 10 mg/d for 21 days of a 28-day cycle and weekly 5-mg dose escalations to a target of 25 mg, we encountered severe toxicities (tumor lysis, fatal sepsis) in the first two patients enrolled. The study was halted and the protocol amended to a more conservative regimen: starting dose of lenalidomide 2.5 mg with monthly escalations to a target dose of 10 mg, and extended tumor lysis prophylaxis and monitoring. Gene expression profiles from patient samples before and after 7 days of lenalidomide were performed. Twenty-five patients were enrolled on the amended protocol. No further tumor lysis events were reported. Tumor flare was common (88%) but mild. Grade 3 to 4 neutropenia occurred in 72% of patients, with only five episodes of febrile neutropenia. The overall response rate was 56% (no complete responses). Although rapid peripheral lymphocyte reductions were observed, rebound lymphocytoses during the week off-therapy were common. Lenalidomide-induced molecular changes enriched for cytoskeletal and immune-related genes were identified. Lenalidomide is clinically active as first-line CLL therapy and is well-tolerated if a conservative approach with slow dose escalation is used. A lenalidomide-induced molecular signature provides insights into its immunomodulatory mechanisms of action in CLL.

CDDO-imidazolide mediated inhibition of malignant cell growth in Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a B-cell malignancy that remains incurable. Synthetic triterpenoids (ST), 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), its methyl ester derivative (CDDO-Me) and imidazolide derivative (CDDO-Im) induce cell death and inhibit growth of various malignancies and hold promise as treatment for cancer patients. We examined the therapeutic potential of these compounds in WM. All three forms of CDDO induced equal toxicity in BCWM.1 cells. In malignant B cells from WM patients, CDDO-Im induced the greatest toxicity. CDDO-Im inhibited proliferation at nanomolar concentrations and arrested the cells in G0/G1. CDDO-Im induced apoptotic cell death that was partially abolished in the presence of caspase inhibitor. CDDO-Im also inhibited survival pathways that have been shown to be important in WM. Overall, our data suggest that ST are likely to provide therapeutic efficacy for WM patients.

Preferential Inhibition of Malignant Cell Growth by CDDO in Waldenström Macroglobulinemia.

Waldenström macroglobulinemia (WM) is a B cell disorder with a highly variable clinical outcome, where some patients remain asymptomatic, while others have significant symptoms and require therapeutic intervention. Clinical symptoms include infiltration of lymphoplasmacytic cells into the bone marrow, production of a monoclonal IgM protein, anemia, lymphadenopathy, and serum hyperviscosity. Despite the introduction of multiple chemotherapeutic regimens over the past several decades, WM remains an incurable disease. 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) and its methyl ester derivative (CDDO-Me) and imidazolide derivative (CDDO-Im) are synthetic triterpenoids derived from oleanolic acid. These compounds have been shown to induce apoptosis of several tumor cell types including breast cancer, lung cancer, ovarian cancer, melanoma, osteosarcoma, leukemia, and multiple myeloma cells. The goal of this study was to evaluate the potential role of synthetic triterpenoids in WM. Preliminary studies on malignant B cells indicated that CDDO-Im induced the greatest amount of cell death and we therefore used this derivative of CDDO for our studies. CD19+ CD138+ cells from bone marrow biopsy specimens obtained from WM patients were isolated by positive selection and were treated with varying concentrations of CDDO-Im (62.5 nM to 750 nM ) and cell viability was determined after 24 hours (n=3). Compared to the nil control 47% of the malignant cells remained viable at a CDDO-Im concentration of 62.5 nM and only 11% remained viable at 125 nM CDDO-Im. To determine if CDDO-Im had specific toxic effects on non-malignant cells, we cultured CD19- CD138- cells from WM patient bone marrows with CDDO-Im and found that non-malignant cells were less sensitive to the drug, 80% being viable at 62.5 nM and 65% being viable at 125 nM. Similarly, we found that normal peripheral blood B cells and CD19+ CD138+ bone marrow B cells from healthy donors were less sensitive to CDDO-Im. Compared to the nil control 93% of the CD19+ CD138+ bone marrow B cells and 70% of the peripheral blood B cells remained viable at a CDDO-Im concentration of 62.5 nM and 95% and 68% remained viable at 125 nM CDDO-Im respectively. We next examined the effect of CDDO-Im on WM cell proliferation and found that CDDO-Im inhibited cell proliferation in a dose-dependent manner. Similar to the viability assays, there was a differential effect of CDDO-Im on malignant and non-malignant cells. Compared to the nil control, at 125 nM, there was a complete inhibition of malignant cell growth, while approximately 40% of the non-malignant cells remained proliferative. To determine the mechanism of cell death, CD19+ CD138+ cells were cultured in the presence or absence of various doses of CDDO-Im for 6 hours and cell lysates were examined for cleavage of PARP. There was evidence of PARP cleavage in a dose-dependent manner, suggesting that CDDO-Im induced malignant cell death occurs through a caspase-dependent mechanism. In summary, the synthetic triterpenoid CDDO-Im decreased the viability of WM B cells in a dose-dependent manner, and CDDO-Im had a greater effect on the viability of the malignant cells compared to non-malignant cells from the same WM patients. CDDO-Im also inhibited malignant cell growth in a dose-dependent manner and the mechanism of CDDO-Im mediated cell death appears to be a caspase-mediated event. Overall, our data indicate that CDDO-Im may have potential efficacy in WM patients.

Elasmobranch immune cells as a source of novel tumor cell inhibitors: Implications for public health

SYNOPSIS: Reports that elasmobranchs (sharks, skates, and rays) may have a low incidence of disease have stimulated interest in understanding the role of their immune system in this apparent resistance. Although research in this area may potentially translate into applications for human health, a basic understanding of the elasmobranch immune system components and how they function is essential. As in higher vertebrates, elasmobranch fishes possess thymus and spleen, but in the absence of bone marrow and lymph nodes, these fish have evolved unique lymphomyeloid tissues, namely epigonal and Leydig organs. As conditions for short-term culture of elasmobranch immune cells have become better understood, the opportunity to examine functional activity of cytokine-like factors derived from conditioned culture medium has resulted in the identification of growth inhibitory activity against a variety of tumor cell lines. Specifically, the medium enriched by short term culture of bonnethead shark (Sphyrna tiburo) epigonal cells (epigonal conditioned medium, ECM) has been shown to inhibit the growth of mammalian tumor cell lines, including fibrosarcoma (WEHI-164), melanoma (A375.S2), B-cell lymphoma (Daudi), T-cell leukemia (Jurkat), pancreatic cancer (PANC-1), ovarian cancer (NIH:OVCAR-3), and three breast carcinoma cell lines (MCF7, HCC38, Hs578T). Of the cell lines tested, WEHI-164, A375.S2, Daudi, and Jurkat cells were among the most sensitive to growth inhibitory activity of ECM whereas PANC-1 and NIH:OVCAR-3 cells were among the least sensitive. In addition, ECM demonstrated preferential growth inhibition of malignant cells in assays against two different malignant/non-malignant cell line pairs (HCC38/HCC38 BL and Hs 578T/Hs 578Bst). Separation of protein components of ECM using SDS-PAGE resulted in a very reproducible pattern of three major bands corresponding to molecular sizes of approximately 40-42 kD, 24 kD, and 17 kD. Activity is lost after heating at 75 degrees C for 30 min, and can be diminished by treatment with proteinase K and protease. Activity is not affected by treating with trypsin, DNase I or RNase A.

Effect of trichostatin A, a histone deacetylase inhibitor, on glioma proliferation in vitro by inducing cell cycle arrest and apoptosis

Trichostatin A (TSA) is a histone deacetylase inhibitor that causes growth inhibition of malignant cells. The authors' goal was to evaluate its effect on cell growth and cell cycle regulation in a large panel of glioma cell lines, as well as in human astrocytes, fibroblasts, and endothelial cells. Cell growth in response to TSA was evaluated using a tetrazolium colorimetric assay and a clonogenic assay. Cell cycle effects were examined using flow cytometry. A DNA fragmentation assay was used to evaluate induction of apoptosis. Histone acetylation status and the expression of p21WAF1, phosphorylated retinoblastoma protein (Rb), poly(adenosine diphosphate-ribose) polymerase (PARP), and caspase-3 were studied using Western blot analysis. In the glioma cell lines, there was significant inhibition of cell growth and detection of increased levels of acetylated histones after TSA treatment. The mechanisms underlying the growth inhibition include cell cycle arrest at the G2/M phase and apoptosis induction. The expression of p21WAF1 was activated, with a temporally related decrease in levels of phosphorylated Rb. Apoptosis was preceded by detection of cleaved PARP and activated caspase-3. The effects of TSA were less pronounced or absent in human astrocytes, fibroblasts, and endothelial cells. The TSA caused inhibition of glioma cell growth by both cell cycle arrest and apoptosis. Cell cycle arrest was associated with an increase in p21WAF1 expression and a decrease in phosphorylated Rb. Apoptosis was mediated at least partly through the activation of caspase-3. Because of the differential effects in glioma cells compared with nonneoplastic cells, TSA may provide a novel strategy for achieving tumor growth inhibition and cytotoxicity. Further investigation is warranted.

Tyrosine kinase inhibitor resistance in cancer: role of ABC multidrug transporters

Recent antitumor drug research has seen the development of a large variety of tyrosine kinase inhibitors (TKIs) with increasing specificity and selectivity. These are highly promising agents for specific inhibition of malignant cell growth and metastasis. However, their therapeutic potential also depends on access to their intracellular targets, which may be significantly affected by certain ABC membrane transporters. It has been recently shown that several human multidrug transporter ABC proteins interact with specific TKIs, and the ABCG2 transporter has an especially high affinity for some of these kinase inhibitors. These results indicate that multidrug resistance protein modulation by TKIs may be an important factor in the treatment of cancer patients; moreover, the extrusion of TKIs by multidrug transporters may result in tumor cell TKI resistance. Interaction with multidrug resistance ABC transporters may also significantly modify the pharmacokinetics and toxicity of TKIs in patients.

High-affinity interaction of tyrosine kinase inhibitors with the ABCG2 multidrug transporter.

Tyrosine kinase inhibitors (TKIs) are promising new agents for specific inhibition of malignant cell growth and metastasis formation. Because most of the TKIs have to reach an intracellular target, specific membrane transporters may significantly modulate their effectiveness. In addition, the hydrophobic TKIs may interact with so-called multidrug transporters and thus alter the cellular distribution of unrelated pharmacological agents. In the present work, we show that certain TKIs, already in the clinical phase of drug development, directly interact with the ABCG2 multidrug transporter protein with a high affinity. We found that in several in vitro assay systems, STI-571 (Gleevec; imatinib mesylate), ZD1839 (Iressa; gefitinib), and N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]-2-butynamide (EKI-785) interacted with ABCG2 at submicromolar concentrations, whereas other multidrug transporters, human multidrug resistance protein (P-glycoprotein, ABCB1) and human multidrug resistance protein 1 (ABCC1), showed much lower reactivity toward these agents. Low concentrations of the TKIs examined selectively modulated ABCG2-ATPase activity, inhibited ABCG2-dependent active drug extrusion, and significantly affected drug resistance patterns in cells expressing ABCG2. Our results indicate that multidrug resistance protein modulation by TKIs may be an important factor in the clinical treatment of cancer patients. These data also raise the possibility that an extrusion of TKIs by multidrug transporters, e.g., ABCG2, may be involved in tumor cell TKI resistance.

Activation of Rac1 and the p38 Mitogen-activated Protein Kinase Pathway in Response to Arsenic Trioxide

Arsenic trioxide induces differentiation and apoptosis of malignant cells in vitro and in vivo, but the mechanisms by which such effects occur have not been elucidated. In the present study we provide evidence that arsenic trioxide induces activation of the small G-protein Rac1 and the alpha and beta isoforms of the p38 mitogen-activated protein (MAP) kinase in several leukemia cell lines. Such activation of Rac1 and p38-isoforms results in downstream engagement of the MAP kinase-activated protein kinase-2 and is enhanced by pre-treatment of cells with ascorbic acid. Interestingly, pharmacological inhibition of p38 potentiates arsenic-dependent apoptosis and suppression of growth of leukemia cell lines, suggesting that this signaling cascade negatively regulates induction of antileukemic responses by arsenic trioxide. Consistent with this, overexpression of a dominant-negative p38 mutant (p38betaAGF) enhances the antiproliferative effects of arsenic trioxide on target cells. To further define the relevance of activation of the Rac1/p38 MAP kinase pathway in the induction of arsenic-dependent antileukemic effects, studies were performed using bone marrows from patients with chronic myelogenous leukemia. Arsenic trioxide suppressed the growth of leukemic myeloid (CFU-GM) progenitors from such patients, whereas concomitant pharmacological inhibition of the p38 pathway enhanced its growth-suppressive effects. Altogether, these data provide evidence for a novel function of the p38 MAP kinase pathway, acting as a negative regulator of arsenic trioxide-induced apoptosis and inhibition of malignant cell growth.

Evidence for involvement of Wnt signaling pathway in IB-MECA mediated suppression of melanoma cells.

The A3 adenosine receptor, A3AR, belongs to the family of Gi proteins, which upon induction, suppresses the formation of cAMP and its downstream effectors. Recent studies have indicated that activation of A3AR by its agonist, IB-MECA, results in growth inhibition of malignant cells. Here we demonstrate the ability of IB-MECA to decrease the levels of protein kinase A, a downstream effector of cAMP, and protein kinase B/Akt in melanoma cells. Examination of glycogen synthase kinase 3beta, GSK-3beta, whose phosphorylation is controlled by protein kinase A and B, showed a substantial decrease in the levels of its phosphorylated form and an increase in total GSK-3beta levels in IB-MECA treated melanoma cells. This observation suggests that the treatment of cells with IB-MECA augments the activity of GSK-3beta in the cells. Evaluation of beta-catenin, a key component of Wnt signaling pathway which, upon phosphorylation by GSK-3beta rapidly ubiquitinates, showed a substantial decrease in its level after IB-MECA treatment. Accordingly, the level of beta-catenin responsive cell growth regulatory genes including c-myc and cyclin D1 was severely declined upon treatment of the cells with IB-MECA. These observations which link cAMP to the Wnt signaling pathway provide mechanistic evidence for the involvement of Wnt pathway via its key elements GSK-3beta and beta-catenin in the anti-tumor activity of A3AR agonists.

Inhibition of tumor cell growth by protein factors derived from the developing mouse brain.

It was recently reported (Endoh et al. 1981, Exp Cell Biol 49:272-277) that conditioned medium of neonatal mouse brain (CM-NB) inhibited the growth of mouse neuroblastoma cells. In this work we fractionated CM-NB by size exclusion high performance liquid chromatography, and separated two active principles (28,000 and 62,000 daltons) Each or a combination of the 28,000 and 62,000 dalton fractions showed a differential inhibitory effect on DNA synthesis or clonal growth of the three human lung cell lines: the normal diploid fibroblast WI38 cells were less susceptible than their simian virus 40-transformed VA13 cells and carcinoma A549 cells. This preferential growth-inhibition of malignant cells was also observed for rat fibroblast 3Y1 and its simian virus 40-transformed W3Y cells, and for two other normal and five other malignant cell lines. The growth-inhibitory activity of CM-NB or the 28,000 and 62,000 dalton fractions was lost by pronase, trypsin, tetrahydrofuran, acetonitrile, or dithiothreitol in the presence of guanidine, and also labile to heat, vigorous agitation, or freeze-thawing. The activity was also found in the conditioned medium of prenatal mouse brain, but not in either the conditioned medium of the adult brain and of the secondary culture of the neonatal brain, or in the homogenate and rinsing fluid of the neonatal brain. Thus the mouse brain at the terminal stage of ontogenesis liberates proteinaceous factors, which exhibit a preferential growth-inhibition of tumor or transformed cells and act on malignant cells of human and rodent origin.

Growth inhibition of malignant cells in vitro by a certain isoenzyme (author's transl)

Growth inhibition of malignant cells in vitro by a certain isoenzyme (author's transl)