Evaluation of the efficacy of potential antineoplastic drugs on tumour metastasis by a computer-assisted image analysis

Phytochemicals as Immunomodulatory Agents in Melanoma

Cutaneous melanoma is an immunogenic highly heterogenic tumor characterized by poor outcomes when it is diagnosed late. Therefore, immunotherapy in combination with other anti-proliferative approaches is among the most effective weapons to control its growth and metastatic dissemination. Recently, a large amount of published reports indicate the interest of researchers and clinicians about plant secondary metabolites as potentially useful therapeutic tools due to their lower presence of side effects coupled with their high potency and efficacy. Published evidence was reported in most cases through in vitro studies but also, with a growing body of evidence, through in vivo investigations. Our aim was, therefore, to review the published studies focused on the most interesting phytochemicals whose immunomodulatory activities and/or mechanisms of actions were demonstrated and applied to melanoma models.

Antimetastatic pectic polysaccharide from Decalepis hamiltonii; galectin-3 inhibition and immune-modulation

Melanoma is a malignant neoplasm of major concern because of its high mortality rate and failure of chemotherapy. Previously we have shown that galectin-3, a galactose specific lectin, plays a pivotal role in the initiation of metastasis. It was hypothesized that blocking galectin-3 with galactose rich dietary pectic polymer would inhibit metastasis. The current study analyzes the preventive effect and mode of action of a pectic polymer from Swallow Root (Decalepis hamiltonii) in a preventative study of B16F10 cells lung colonization. Matrix metalloproteinase (MMPs) activity was assayed by zymography. Apoptotic/proliferative markers and cytokines were analyzed by immunoassay. Results indicated ~88% inhibition of lung colonization by SRPP as compared to 60% by CPP and only 7% by GRPP. Further molecular analysis revealed that galectin-3 blockade was associated with down regulation of MMPs and NFκB. Activation of caspases supported the apoptotic effect of SRPP. Infiltration of inflammatory cells into the lung was evidenced by presence of CD11b+ cells and release of the pro-inflammatory cytokine-IL-17, indicating inflammation during the cancer cell colonization process. SRPP enhanced the release of IL-12 that enables the reduction of inflammation. Our data for the first time indicate the effective anti-metastatic effect of SRPP due to both galectin-3 blockade and immunomodulation.

Hinokitiol, a tropolone derivative, inhibits mouse melanoma (B16-F10) cell migration and in vivo tumor formation

Invasion and metastasis are the major causes of treatment failure in patients with cancer. Hinokitiol, a natural bioactive compound found in Chamacyparis taiwanensis, has been used in hair tonics, cosmetics, and food as an antimicrobial agent. In this study, we investigated the effects and possible mechanisms of action of hinokitiol on migration by the metastatic melanoma cell line, B16-F10, in which matrix metalloproteinase-1 (MMP-1) is found to be highly- expressed. Treatment with hinokitiol revealed a concentration-dependent inhibition of migration of B16-F10 melanoma cells. Hinokitiol appeared to achieve this effect by reducing the expression of MMP-1 and by suppressing the phosphorylation of mitogen- activated protein kinase (MAPK) signaling molecules such as extracellular signal-regulated kinase (ERK) 1/2, p38 MAPK and c-Jun N-terminal kinases (JNK). On the other hand, hinokitiol treatment reversed IκB-α degradation and inhibited the phosphorylation of p65 nuclear factor kappa B (NF-κB) and cJun in B16-F10 cells. In addition, hinokitiol suppressed the translocation of p65 NF-κB from the cytosol to the nucleus, suggesting reduced NF-κB activation. Consistent with these in vitro findings, our in vivo study demonstrated that hinokitiol treatment significantly reduced the total number of mouse lung metastatic nodules and improved histological alterations in B16-F10 injected C57BL/6 mice. These findings suggest that treatment of B16-F10 cells with hinokitiol significantly inhibits metastasis, possibly by blocking MMP-1 activation, MAPK signaling pathways and inhibition of the transcription factors, NF-κB and c-Jun, involved in cancer cell migration. These results may accelerate the development of novel therapeutic agents for the treatment of malignant cancers.

Cytotoxic, antitumour and antimetastatic activity of two new polyacetylenes isolated from Vernonia scorpioides (Lam.) Pers

Vernonia scorpioides (Lam.) Pers., popularly known as Enxuga, Erva-de-São Simão and Piracá, has been used in folk medicine for its anti-inflammatory, wound healing and antimicrobial properties. Two polyacetylenes, 5-octa-2,4,6-triynyl-furan-2(5H)-one (1) and 8'-hydroxy 3-4 dihydrovernoniyne (2), were isolated from the dichloromethane extract fraction of V. scorpioides. In this study, polyacetylene 1 demonstrated a more potent cytotoxic activity than 2 in the tumour cell lines examined, and cytotoxicity was found to be comparable to a commercial drug (p > 0.05) in melanoma cells. No significant cytotoxic effect was observed in normal cell lines. Furthermore, polyacetylene 1 induced an in vitro increase in caspase-3 activity in B16F10 cells. When polyacetylene 1 was administered intraperitoneally (i.p.) in mice, a reduction in solid tumour volume and metastasis was observed in mice injected with B16F10 cells. An increase in locomotor activity was also observed in mice with solid tumours, and an inhibition of mechanical hypersensitivity was observed in a mouse model of metastasis. Notably, no significant morphological change was observed in several organs harvested from the treated mice. In conclusion, in vitro and in vivo anticancer activity of polyacetylene 1 was consistently observed and involved the induction of apoptosis by the activation of caspase-3. The anticancer activity demonstrated by polyacetylene 1, together with the absence of preliminary toxicological effects, represents a new and interesting option for the management of neoplastic disease.

Tissue transglutaminase activity protects from cutaneous melanoma metastatic dissemination: an in vivo study

The role of tissue transglutaminase (TG-2, TGase-2) in cancer development is still a fascinating field of research. The available reports do not elucidate fully its mechanism of action, due to the limitations of in vitro approaches. Therefore, to understand TG-2 role in cancer, we carried out an in vivo study with a more direct approach. TG-2 was in vivo overexpressed in a murine model of melanoma (intravenous injection of B16 melanoma cells in C57BL/6N mice) by means of a plasmid carrying the TG-2 cDNA. The evaluation of the frequency and size of the metastases indicated that the number of melanoma lung foci was more markedly reduced by TG-2 overexpression than the metastatic size. Then, TG-2 overexpressing mice showed a prolonged survival with respect to control mice. Further analyses were carried by means of proteomic analysis of melanoma cell lysates and meta-analysis of published transcriptomic datasets. Proteomic analysis of cell lysates from a human melanoma cell line compared to human keratinocytes showed significant differences in the expression of TG-2 substrates known to be involved in proliferation/differentiation and cancer progression. Taken together, these findings indicate a protective role of TG-2 enzymatic activity in melanoma progression in vivo.

Similar antineoplastic effects of nimesulide, a selective COX-2 inhibitor, and prostaglandin E1 on B16-F10 murine melanoma cells

There is now increasing evidence that a constitutive expression of cyclooxygenase 2 (COX-2) plays a role in the development and progression of malignant ectodermal tumours. In this study, we investigated whether the selective inhibition of COX-2 would be beneficial in melanoma treatment. Nimesulide, a selective inhibitor of COX-2 that causes the breakdown of proinflammatory 2-series prostaglandins (PG2), adversely affected the growth of B16-F10 melanoma cells through the induction of differentiation. The intracellular levels of polyamine, as a proliferation marker, were reduced by the treatment; at the same time, transglutaminase activation and increase in melanin content, as differentiation indicators, were observed. The potential antimetastatic activity of the drug was further shown by means of the Boyden invasion assay and gelatin zymography for metalloproteinase activity. Comparable results were obtained after the treatment of cells with one of the 1-series PGs (PGE1). Therefore, our hypothesis is that the antineoplastic activity observed for nimesulide may be ascribed to intracellular changes in alterations in PG levels.

Update on uses and properties of citrus flavonoids: new findings in anticancer, cardiovascular, and anti-inflammatory activity

Significantly, much of the activity of Citrus flavonoids appears to impact blood and microvascular endothelial cells, and it is not surprising that the two main areas of research on the biological actions of Citrus flavonoids have been inflammation and cancer. Epidemiological and animal studies point to a possible protective effect of flavonoids against cardiovascular diseases and some types of cancer. Although flavonoids have been studied for about 50 years, the cellular mechanisms involved in their biological action are still not completely known. Many of the pharmacological properties of Citrus flavonoids can be linked to the abilities of these compounds to inhibit enzymes involved in cell activation. Attempts to control cancer involve a variety of means, including the use of suppressing, blocking, and transforming agents. Suppressing agents prevent the formation of new cancers from procarcinogens, and blocking agents prevent carcinogenic compounds from reaching critical initiation sites, while transformation agents act to facilitate the metabolism of carcinogenic components into less toxic materials or prevent their biological actions. Flavonoids can act as all three types of agent. Many epidemiological studies have shown that regular flavonoid intake is associated with a reduced risk of cardiovascular diseases. In coronary heart disease, the protective effects of flavonoids include mainly antithrombotic, anti-ischemic, anti-oxidant, and vasorelaxant. It is suggested that flavonoids decrease the risk of coronary heart disease by three major actions: improving coronary vasodilatation, decreasing the ability of platelets in the blood to clot, and preventing low-density lipoproteins (LDLs) from oxidizing. The anti-inflammatory properties of the Citrus flavonoids have also been studied. Several key studies have shown that the anti-inflammatory properties of Citrus flavonoids are due to its inhibition of the synthesis and biological activities of different pro-inflammatory mediators, mainly the arachidonic acid derivatives, prostaglandins E 2, F 2, and thromboxane A 2. The anti-oxidant and anti-inflammatory properties of Citrus flavonoids can play a key role in their activity against several degenerative diseases and particularly brain diseases. The most abundant Citrus flavonoids are flavanones, such as hesperidin, naringin, or neohesperidin. However, generally, the flavones, such as diosmin, apigenin, or luteolin, exhibit higher biological activity, even though they occur in much lower concentrations. Diosmin and rutin have a demonstrated activity as a venotonic agent and are present in several pharmaceutical products. Apigenin and their glucosides have been shown a good anti-inflammatory activity without the side effects of other anti-inflammatory products. In this paper, we discuss the relation between each structural factor of Citrus flavonoids and the anticancer, anti-inflammatory, and cardiovascular protection activity of Citrus flavonoids and their role in degenerative diseases.

Protein-polyamine conjugates by transglutaminase 2 as potential markers for antineoplastic screening of natural compounds

The role of post-translational modification of cell proteins with polyamines, a reaction catalyzed by a tissue tranglutaminase (TG, EC 2.3.2.13), in the induction of cell differentiation, represents an intriguing strategy to control cell proliferation and metastatic ability of different tumor cell lines. In this review, we focus our attention on the metabolic aspects of some natural compounds (methylxantines, retinoids and flavonoids) responsible of their antitumor effects exerted through the induction of TG activity in cancer cells.

Role of transglutaminase 2 in quercetin-induced differentiation of B16-F10 murine melanoma cells

Flavonoids belong to the class of plant polyphenolic compounds with over 6,000 individual structures known. These phytochemicals have attracted the interest of the scientists, because they possess a remarkable spectrum of biological activities, such as antiallergic, antiinflammatory, antioxidant, antimutagenic and anticarcinogenic. In this work, we compared the anticancer potential of two flavonoids, quercetin and pelargonidin, on highly metastatic B16-F10 melanoma murine cells. We have evaluated different parameters related to cell proliferation and differentiation, such as cell number, toxicity, intracellular content of polyamines and transglutaminase (TG, EC 2.3.2.13) activity. The higher inhibition of tumor cell growth, with respect to control, was obtained with quercetin cell treatment, i.e. 32% reduction after 48 h and 39% reduction after 72 h of incubation (P < 0.001). In parallel, quercetin-treated cells showed a similar decrease in polyamine content. TG activity was fourfold increased, with respect to control, after 48 h and twofold increased after 72 h (P < 0.001). Pelargonidin treatment did not show significant antiproliferative effects and any increase in TG activity. Proteomic approach was used to investigate changes in protein expression profiles in tumor cells following quercetin treatment. Changes in expression of 60 proteins were detected, i.e. 8 proteins were down-regulated, 35 up-regulated, 11 "de novo" synthetized proteins and 6 suppressed proteins were present in treated cells. A 80 kDa spot, identified as TG type 2 by Western blot analysis, presented a fourfold increase in intensity, confirming the key role played by TG in the induction of cancer cell differentiation.

Decrease of polyamine levels and enhancement of transglutaminase activity in selective reduction of B16-F10 melanoma cell proliferation induced by atrial natriuretic peptide

The atrial natriuretic peptide (ANP) at physiological levels reduced the proliferation of highly metastatic murine (B16-F10) and human (SK-MEL 110) melanoma cell lines whereas rat aortic smooth muscle (RASM) cells were unaffected. In RASM cells, the levels of proliferation markers (putrescine, spermidine and spermine) increase after 24 h of epidermal growth factor (EGF) stimulation (RASM-EGF), but strongly decrease after 24 h of exposition to ANP. The B16-F10 cell line, which received no EGF stimulation, showed a similar decrease in polyamine content after ANP treatment. Furthermore, the enzymatic activity of a differentiation marker (transglutaminase) was increased for both RASM-EGF and B16-F10 cells after 24 h of treatment with 10(-10) mol/l ANP, concomitantly with the observed inhibition of polyamine biosynthesis and cell growth. Data obtained on B16-F10 cells treated with 8Br-GMPc or with an ANP analogue (cANF) support the involvement of the type C ANP receptor (NRP-C) in hormone effects. From the overall results, it appears that ANP may play a role in the inhibition of cellular growth under hyperproliferative conditions, as shown for RASM-EGF cells. The B16-F10 melanoma cell line showed similar results, but in the absence of mitogen stimulation. This observation suggests that the constitutive hyperproliferative state of tumor cells may be a sufficient condition to favor the ANP inhibitory effects on cell growth. This finding is particularly interesting in the light of a possible use of ANP as a potential selective antineoplastic agent.

Enhancement of transglutaminase activity and polyamine depletion in B16-F10 melanoma cells by flavonoids naringenin and hesperitin correlate to reduction of the in vivo metastatic potential

The in vitro and in vivo effects of two flavonons, naringenin (NG) and hesperitin (HP) on the proliferation rate of highly metastatic murine B16-F10 melanoma cell were investigated. NG or HP treatment of melanoma cells produced a remarkable reduction of cell proliferation, paralleled with both the lowering of the intracellular levels of polyamine, spermidine and spermine and the enhancement of transglutaminase (TGase, EC 2.3.2.13) activity. Orally administered NG or HP in C57BL6/N mice inoculated with B16-F10 cells affected the pulmonary invasion of melanoma cells in an in vivo metastatic assay. The number of lung metastases detected by a computerized image analyzer was reduced, compared to untreated animals, by about 69% in NG-treated mice and by about 36% in HP-treated mice. Survival studies showed that 50% of the NG-treated animals died 38 +/- 3.1 days after tumor cell injection (control group: 18 +/- 1.5 days) and HP-treated mice died 27 +/- 2.3 days after cell inoculation. Taken together, these findings provide further evidences for the potential anticancer properties of dietary flavonoids as chemopreventive agents against malignant melanoma.

Treatment of metastatic melanoma B16F10 by the flavonoids tangeretin, rutin, and diosmin

Melanoma is one of the most frequently metastasizing malignant neoplasias. This study examines an experimental model of pulmonary metastasis and the B16F10 cell subline, highly metastatic in the lung. Antimetastatic effects of the flavonoids tangeretin, rutin, and diosmin were analyzed, and at the same time an analysis of the metastatic activity of ethanol was performed, considered to be necessary because it is used as a vehicle for administering the flavonoids. Lentini's model, which complements the macroscopic evaluation of nodule numbers by using a stereoscopic microscope and image analysis at the microscopic level, was used. The greatest reduction in the number of metastatic nodules (52%) was obtained with diosmin; similarly, the percentages of implantation, growth index, and invasion index (79.40, 67.44, and 45.23%, respectively), were all compared with those of the ethanol group, considered to be an effective control group. Rutin- and tangeretin-treated groups also showed reductions of the same index compared with the ethanol group. It would seem that structural factors would better explain these results and the antimetastatic activity of each flavonoid and the respective metabolites.

Modelo experimental de tratamiento con extracto de semillas de uva, vino tinto y etanol del melanoma metastásico pulmonar

INTRODUCTION

Melanoma is one of the neoplasias that most frequently metastasize, especially in the lung, where represents a challenge in oncology since current treatment is ineffective, and mortality is high.

MATERIAL AND METHODS

Swiss mice (n = 52) were inoculated with 0.5 x 106 B16F10 cell lines and, later, given an oral administration of grape-seed extract, red wine or ethanol. Metastatic nodules on the lung surface were counted and, after processing for microscopy, five sections were selected for image analysis and the invasion index was calculated.

RESULTS

Macroscopic analysis showed that grape-seed extract and red wine reduced the number of metastatic nodules by 26.07 and 20.81%, respectively, compared with a control group treated with ethanol. Microscopically, the reduction in the invasion index was 31.65 for grape-seed extract and 17.57% for red wine.

CONCLUSION

Ethanol administration significantly increased pulmonary metastasis while grape-seed extract and red wine led to their reduction.

Platelet-derived growth factor inhibits basic fibroblast growth factor angiogenic properties in vitro and in vivo through its alpha receptor

Basic fibroblast growth factor (bFGF) and platelet-derived growth factor-BB (PDGF-BB) modulate vascular wall cell function in vitro and angiogenesis in vivo. The aim of the current study was to determine how bovine aorta endothelial cells (BAECs) respond to the simultaneous exposure to PDGF-BB and bFGF. It was found that bFGF-dependent BAEC migration, proliferation, and differentiation into tubelike structures on reconstituted extracellular matrix (Matrigel) were inhibited by PDGF-BB. The role played by PDGF receptor alpha (PDGF-Ralpha) was investigated by selective stimulation with PDGF-AA, by blocking PDGF-BB-binding to PDGF-Ralpha with neomycin, or by transfecting cells with dominant-negative forms of the receptors to selectively impair either PDGF-Ralpha or PDGF-Rbeta function. In all cases, PDGF-Ralpha impairment abolished the inhibitory effect of PDGF-BB on bFGF-directed BAEC migration. In addition, PDGF-Ralpha phosphorylation was increased in the presence of bFGF and PDGF, as compared to PDGF alone, whereas mitogen-activated protein kinase phosphorylation was decreased in the presence of PDGF-BB and bFGF compared with bFGF alone. In vivo experiments showed that PDGF-BB and PDGF-AA inhibited bFGF-induced angiogenesis in vivo in the chick embryo chorioallantoic membrane assay and that PDGF-BB inhibited bFGF-induced angiogenesis in Matrigel plugs injected subcutaneously in CD1 mice. Taken together these results show that PDGF inhibits the angiogenic properties of bFGF in vitro and in vivo, likely through PDGF-Ralpha stimulation.