Inhibition of the growth of cultured human meningioma cells by recombinant interferon-α

In this paper the results of investigations on the effect of interferon-α (IFN-α) on the growth of meningioma cells in culture is reported. A consecutive series of six meningiomas and one meningioma/neurofibroma derived from a patient with neurofibromatosis type 2 was investigated and it was found that the growth of all seven tumours in response to mitotic stimuli (fetal bovine serum or epidermal growth factor) is strongly inhibited by IFN-α. Maximal response varied between 100% and 70% inhibition of the incorporation of tritiated thymidine. In some cases an inhibitory response was obtained already at very low doses (≤10 U of IFN-α per ml). These results indicate that further clinical investigation of the application of IFN-α to the treatment of meningioma is warranted.     

Altered growth control by natural growth inhibitors in the mutant HD33 substrain of the Ehrlich-Lettré ascites mammary carcinoma

The mutant substrain HD33 of the Ehrlich-Lettré ascites mammary carcinoma (EAC) was found to be altered in its ability to respond to and to produce natural growth inhibitors. Cells of this substrain did not respond to (1) a highly purified growth inhibitor from bovine mammary gland, inhibiting the proliferation of two strains of the original EAC already at concentrations of 0.5–2.0 ng/ml, (2) inhibitory activities found in the ascites fluid of these sensitive strains and partially purified. However, from the ascites fluid of the mutant substrain an inhibitory activity was partially purified, which was inhibitory towards this substrain. It also inhibited the cells from an original strain, although less effectively. This new inhibitory activity is similar in its properties to that of the others investigated in that (1) its mol. wt is between 10,000 and 50,000 D, (2) it is heat labile and (3) its activity can be overcome by insulin, epidermal growth factor and 2′-deoxycytidine, (4) the dose-response curve levels off at 35–45% inhibition. The results demonstrate that the regulation of cell proliferation by endogenous (autocrine) inhibitors can be altered by mutagen treatment.     

Direct inhibition of the transforming growth factor-β pathway by protein-bound polysaccharide through inactivation of Smad2 signaling

Transforming growth factor-β (TGF-β) is involved in the regulation of cell proliferation, differentiation, and apoptosis and is associated with epithelial-mesenchymal transition (EMT). Inhibition of the TGF-β pathway is an attractive strategy for the treatment of cancer. We recently screened for novel TGF-β inhibitors among commercially available drugs and identified protein-bound polysaccharide (PSK) as a strong inhibitor of the TGF-β-induced reporter activity of 3TP-lux, a TGF-β1-responsive luciferase reporter. Protein-bound polysaccharide is used as a non-specific immunostimulant for the treatment of gastric and colorectal cancers in Japan. The anticancer activity of this agent may involve direct regulation of growth factor production and enzyme activity in tumors in addition to its immunomodulatory effect. Although several clinical studies have shown the beneficial therapeutic effects of PSK on various types of tumors, its mechanism of action is not clear. In the present study, Western blot analysis showed that PSK suppressed the phosphorylation and nuclear localization of the Smad2 protein, thereby suggesting that PSK inhibits the Smad and MAPK pathways. Quantitative PCR analysis showed that PSK decreased the expression of several TGF-β pathway target genes. E-cadherin and vimentin immunohistochemistry showed that PSK suppressed TGF-β1-induced EMT, and FACS analysis showed that PSK inhibited the EMT-mediated generation of CD44(+) /CD24(-) cells. These data provide new insights into the mechanisms mediating the TGF-β-inhibiting activity of PSK and suggest that PSK can effectively treat diseases associated with TGF-β signaling.     

Gene expression profiling of cancer by use of DNA arrays: how far from the clinic?

DNA arrays allow the simultaneous analysis of expression levels for thousands of genes in normal and pathological tissues and hold great promise in molecular medicine, notably in cancer research. The great biological and clinical diversity present in human tumours is poorly characterised by the current classification systems. DNA arrays can provide a better understanding of oncogenesis, leading to improvements in cancer management. First, the identification of new target genes and pathways will allow the development of specific molecular-based anticancer drugs. Secondly, expression profiles will permit tumour classification in more homogeneous diagnostic and prognostic groups, as well as the identification of new clinically and biologically relevant tumour subclasses. Here, we review the technology and present some cancer studies with promising results. Finally, we discuss some of the issues that must be resolved in the near future, so that DNA arrays can fulfil the aims mentioned above.     

On the role of transforming growth factor-β in the growth inhibitory effects of retinoic acid in human pancreatic cancer cells

Background  

Retinoids are potent growth inhibitory and differentiating agents in a variety of cancer cell types. We have shown that retinoids induce growth arrest in all pancreatic cancer cell lines studied, regardless of their p53 and differentiation status. However, the mechanism of growth inhibition is not known. Since TGF-β2 is markedly induced by retinoids in other cancers and mediates MUC4 expression in pancreatic cancer cells, we investigated the role of TGF-β in retinoic acid-mediated growth inhibition in pancreatic cancer cells.     

Down-regulation of transforming growth factor-β and interleukin-10 secretion from malignant glioma cells by cytokines and anticancer drugs

The effect of treatment with interleukin-1 (IL-1), interferon- (IFN-), vincristine, and etoposide was evaluated on the secretion of transforming growth factor- (TGF-) and IL-10 and the expression of major histocompatibility complex (MHC) class I, intercellular adhesion molecule-1 (ICAM-1), and CD80 molecules by malignant glioma cells. Five malignant glioma cell lines were treated with IL-1, IFN-, and/or anticancer agents (vincristine and etoposide). Combined treatment with IL-1 and IFN- caused greater inhibition of TGF- secretion compared to treatment with IFN-, and almost the same levels of inhibition as treatment with vincristine and etoposide. The greatest inhibition of TGF- secretion was achieved by treatment with all agents. Low levels of IL-10 secretion were determined in two out of five malignant glioma cell lines. This IL-10 secretion was inhibited by treatment with IL-1, IFN-, vincristine, and/or etoposide. Treatment with both cytokines and anticancer agents increased the expression of MHC class I and ICAM-1 in all tumor cell lines. The mean increase of expression of MHC class I was 50% and that of ICAM-1 was 12-fold. No tumor cell lines expressed CD80 molecules on the cell surface, and no treatment caused CD80 expression. These results suggest that TGF- and IL-10 secretion by malignant glioma cells can be suppressed by treatment with a combination of IL-1, IFN-, vincristine, and etoposide, and the treatment up-regulates MHC class I and ICAM-1 expression on tumor cells. These results have implications for immunotherapy and chemotherapy in patients with malignant tumors.     

LncRNA PlncRNA-1 overexpression inhibits the growth of breast cancer by upregulating TGF-β1 and downregulating PHGDH

Objective

To investigate the role of lncRNA PlncRNA-1 in the pathogenesis of breast cancer.

Methods

A total of 78 patients with breast cancer as well as 48 healthy females were included in this study. Expression in tumor tissues and adjacent healthy tissues of breast cancer patients, as well as in breast tissues and serum of both patients and healthy control was detected by qRT-PCR. Cell proliferation was detected by CCK-8 assay, and cell apoptosis was tested by MTT assay. PlncRNA-1 overexpression cell lines were constructed and the effects on TGF-β1 as well as phosphoglycerate dehydrogenase (PHGDH) were explored by western blot.

Results

Expression levels of PlncRNA-1 were significantly lower in tumor tissues than those in adjacent healthy tissues. Significantly lower expression levels of PlncRNA-1 were also found in breast cancer patients than those in healthy controls in both breast tissue and serum. Upregulation of PlncRNA-1 promoted the expression of TGF-β1, but inhibited the expression of PHGDH. LncRNA PlncRNA-1 overexpression reduced the proliferation rate, but increased the apoptosis rate of breast cancer cells, while treatment with TGF-β inhibitor reduced those effects of PlncRNA-1 overexpression.

Conclusion

LncRNA PlncRNA-1 overexpression inhibits the growth of breast cancer by upregulating TGF-β1 and downregulating PHGDH.

     

Norcantharidin impairs medulloblastoma growth by inhibition of Wnt/β-catenin signaling

Medulloblastoma is one of the leading causes of morbidity and mortality in pediatric cancer. Wnt-active tumors, an independent molecular subgroup in medulloblastoma, are characterized by a distinct pattern of genomic aberrations. We assessed the anticancer activity of cantharidin and norcantharidin against medulloblastoma, as cell lines in vitro and in athymic nude mice in vivo. Cantharidin and norcantharidin treatment impaired the growth of DAOY and UW228 medulloblastoma cells and promoted the loss of β-catenin activation and the β-catenin nuclearization linked to N-cadherin impairment in vitro. Intra-peritoneal administration of norcantharidin inhibited the growth of intra-cerebellum tumors in orthotopic xenograft nude mice. Analysis of the xenograft tissues revealed enhanced neuronal differentiation and reduced β-catenin expression. Our findings suggest that norcantharidin has potential therapeutic applications in the treatment of medulloblastoma as a result of its ability to cross the blood–brain barrier and its impairment of Wnt-β-catenin signaling.     

Bistable switch in migration stimulating factor expression: regulation by the concerted signalling of transforming growth factor-β1 and the extracellular matrix

Migration stimulating factor (MSF) is an oncofetal motogenic/angiogenic cytokine constitutively expressed by epithelial and stromal cells in fetal and neoplastic tissues. Fibroblasts derived from healthy adult skin do not express MSF but can be induced to do so by treatment with transforming growth factor-β1 (TGF-β1). As the bioactivities of both MSF and TGF-β1 are modulated by the extracellular matrix, we investigated whether the induction of MSF expression by TGF-β1 is also matrix dependent. We now report that adult fibroblasts are induced to express MSF by a transient treatment with TGF-β1 (as short as 2 hr) but only when the cells are adherent to a "wound" matrix, such as denatured type I collagen, fibrin or plastic tissue culture dishes. Unexpectedly, this induction of MSF expression persists unabated for the entire subsequent lifespan of the treated cells in the absence of further TGF-β1 and irrespective of the substratum. Such "activated" MSF expression may, however, be persistently switched off again by a second transient exposure to TGF-β1 but this time only when the cells are adherent to a "healthy" matrix of native type I collagen. Significantly, the constitutive expression of MSF by fetal and cancer patient fibroblasts could also be persistently switched off by this means. We conclude that TGF-β1 may both switch on and switch off MSF expression in a manner critically determined by the nature of the matrix substratum and suggest that this may be a possible mechanism underlying the observed dual functionality of TGF-β1 as both a tumour suppressor and tumour promoter.     

Regulatory role of the transforming growth factor-β signaling pathway in the drug resistance of gastrointestinal cancers

Gastrointestinal (GI) cancer, including esophageal, gastric, and colorectal cancer, is one of the most prevalent types of malignant carcinoma and the leading cause of cancer-related deaths. Despite significant advances in therapeutic strategies for GI cancers in recent decades, drug resistance with various mechanisms remains the prevailing cause of therapy failure in GI cancers. Accumulating evidence has demonstrated that the transforming growth factor (TGF)-β signaling pathway has crucial, complex roles in many cellular functions related to drug resistance. This review summarizes current knowledge regarding the role of the TGF-β signaling pathway in the resistance of GI cancers to conventional chemotherapy, targeted therapy, immunotherapy, and traditional medicine. Various processes, including epithelial-mesenchymal transition, cancer stem cell development, tumor microenvironment alteration, and microRNA biogenesis, are proposed as the main mechanisms of TGF-β-mediated drug resistance in GI cancers. Several studies have already indicated the benefit of combining antitumor drugs with agents that suppress the TGF-β signaling pathway, but this approach needs to be verified in additional clinical studies. Moreover, the identification of potential biological markers that can be used to predict the response to TGF-β signaling pathway inhibitors during anticancer treatments will have important clinical implications in the future.     

Potentiation of the antitumor activity of 5-trifluoromethyl-2′-deoxyuridine by the use of depot forms of the parent compound

Summary 5-Trifluoromethyl-2-deoxyuridine (CF₃dUrd), an antitumor agent, is known to be short-lived in human plasma. Since its rapid elimination from the blood-stream seems to have descouraged the clinical evaluation of this drug, we explored the potential use of masked derivatives of CF₃dUrd as depot forms of the parent compound. First, we observed that the toxicity of CF₃dUrd against HeLA cells in culture was 10⁴ times greater for a 24-h treatment as compared with a 1-h treatment at identical concentrations of the drug, which suggests the importance of using a prolonged treatment period. In fact, the divided dosing of CF₃dUrd to L1210-bearing mice was markedly more effective than its single administration. 5-O-Hexanoyl-,N ³-p-butylbenzoyl-, 5-O-benzyloxymethyl-, and 3-O-benzyl-CF₃dUrd were found to be effective in maitaining the CF₃dUrd concentration in plasma. The oral doses of these agents required to achieve 50% growth inhibition (ED₅₀) in mice bearing sarcoma 180 tumors were 19, 34, 10, and 13 mg kg^–1 day^–1, respectively, whereas that of CF₃dUrd was 63 mg kg^–1 day^–1. The ED₅₀ values for these compounds were inversely correlated with the residence time of CF₃dUrd in plasma. The therapeutic indices of these compounds, calculated as the dose producing a 50% inhibition of body-weight gain (IB₅₀) divided by the ED₅₀ value (1.89, 1,21, 1.40, and 2.15, respectively), were significantly higher than that of CF₃dUrd (0.78). Consequently, these depot forms of CF₃dUrd, particularly 3-O-benzyl-CF₃dUrd, are expected to be more useful than the parent compound as antitumor agents.Abbreviations CF₃dUrd 5-trifluoromethyl-2-deoxyuridine - CF₃dUMP 5-trifluoromethyl-2-deoxyuridine-5-monophospate - S180 sarcoma 180 - L1210 L1210 leukemia - k_el elimination rate constant - T1/2 half-life time - AUC area under the curve - ILS increase in life span - TS thymidylade synthase - FdUMP 5-fluoro-2-deoxyuridine-5 monophosphate - FUra 5-fluorouracil