Proliferation Of B16 Cells Research Articles

Physiochemical and biological properties of phosphorylated polysaccharides from Dictyophora indusiata

In this study, we aim to investigate the physiochemical and biological properties of water-soluble phosphorylated polysaccharides (P-DIP) obtained from a water-insoluble polysaccharide (DIP) extracted from Dictyophora indusiata. A series of physiochemical properties were determined, including morphology, water-solubility, molecular weight, and degree of substitution (DS). To investigate the antioxidant activity of P-DIP, we determined the scavenging activity of hydroxyl radicals and DPPH, as well as the reducing power. MTT assay was performed to determine the cytotoxic effects of DIP and P-DIP on the cellular proliferation of MCF-7 and B16 cells. Compared with DIP, P-DIP showed a satisfactory water-solubility and significant increase in the antioxidant properties. Moreover, P-DIP also showed more significant inhibitory effects on the growth of MCF-7 and B16 tumor cells than the water-insoluble DIP. These results indicated that phosphorylation might contribute to the improvement of water solubility, as well as antioxidant and anti-tumor activities of natural DIP.

Synthesis, structure–activity relationships and biological evaluation of barbigerone analogues as anti-proliferative and anti-angiogenesis agents

A series of barbigerone analogues (7a–7w, 13a–13x) were designed, synthesized and biologically evaluated for their anti-proliferative and anti-angiogenic activities. Among these compounds, compound 13a exhibited the most potent inhibitory effect on the proliferation of HUVECs, HepG2, A375, U251, B16, and HCT116 cells (IC50=3.80, 0.28, 1.58, 3.50, 1.09 and 0.68μM, respectively). Compound 13a inhibited the angiogenesis in zebrafish embryo assay in a concentration-dependent manner. Furthermore, 13a also effectively inhibited the migration and capillary like tube formation of human umbilical vein endothelial cell in vitro. These results support the further investigation of this class of compounds as potential anti-proliferative and anti-angiogenesis agents.

A novel cyclic pentapeptide, H-10, inhibits B16 cancer cell growth and induces cell apoptosis.

Sansalvamide A, a cyclic depsipeptide isolated from a marine fungus of the Fusarium genus, exhibits significant antitumor activity. In the present study, H-10 (molecular formula, C38H55N5O6; molecular weight, 677.8732), a novel sansalvamide A derivative, demonstrated an inhibitory effect on the proliferation of murine melanoma B16 cells. It was confirmed that H-10 induced the apoptosis of the B16 cells. The inhibitory rate of various concentrations of H-10 on the B16 cells was measured by sulforhodamine B colorimetric assay, and the results revealed that the inhibitory effect of H-10 on the B16 cells occurred in a concentration-dependent manner. In addition, a growth curve model of the B16 cells treated with 50 μM H-10 revealed that the effect of H-10 also occurred in a time-dependent manner. The apoptotic morphology of the B16 cells was observed using an optical microscope. Following the treatment of the cells with 50 μM H-10 for 24 h, the cell apoptosis rate was analyzed using flow cytometry. The expression levels of caspase-3, -8 and -9 were analyzed by western blot analysis, and the results indicated that H-10 may induce the apoptosis of B16 cells.

Antineoplastic effect of calycosin on osteosarcoma through inducing apoptosis showing in vitro and in vivo investigations

Recently, increasing studies have documented that tumorigenesis closely relates to apoptotic processes. Thus, inducing apoptosis is an anti-cancer strategy against osteosarcoma. Here we investigated the anti-proliferative effect of calycosin on human osteosarcoma cell (143B) in vitro. The results showed that calycosin dose-dependently inhibited 143B cell proliferation as reflected in tetrazolium salt (MTT) assay (P<0.01). In addition, calycosin effectively down-regulated cellular mRNA expressions of IκBα, NF-κB p65 and cyclin D1 through RT-PCR assay (P<0.01). Next, calycosin-mediated inhibitory effect on 143B tumor-bearing nude mice and the underlying mechanism were evaluated and discussed. As a result, calycosin administration significantly blocked solid tumor growth in 143B-harbored nude mice (P<0.01). Furthermore, intracellular Bcl-2 protein expression was effectively reduced in 143B-harbored tumor tissue through western blotting analysis (P<0.01), while intratumoral Apaf-1 and cleaved Caspase-3 protein levels were up-regulated, respectively (P<0.01). Taken together, calycosin possesses the anti-osteosarcoma potential, in which the mechanism involved was associated with activation of apoptotic, thus inducing apoptosis.

Study of gambogenic acid-induced apoptosis of melanoma B16 cells through PI3K/Akt/mTOR signaling pathways

To discuss the mechanism of gambogenic acid (GNA) in inducing the apoptosis of melanoma B16 cells. The inhibitory effect of GNA on the proliferation of B16 cells was measured by the methyl thiazolyl tetrazolium (MTT) assay. The effect of GNA on B16 cells was detected by the Hoechst 33258 staining. The transmission electron microscopy was used to observe the ultra-structure changes of B16 cells. The changes in PI3K, p-PI3K, Akt, p-Akt, p-mTOR, PTEN proteins were detected by the Western blotting to discuss the molecular mechanism of GNA in inducing the apoptosis of B16 cells. GNA showed a significant inhibitory effect in the growth and proliferation of melanoma B16 cells. The cell viability remarkably decreased with the increase of GNA concentration and the extension of the action time. The results of the Hoechst 33258 staining showed that cells processed with GNA demonstrated apparent apoptotic characteristics. Under the transmission electron microscope, B16 cells, after being treated with GNA, showed obvious morphological changes of apoptosis. The Western blot showed a time-dependent reduction in the p-PI3K and p-Akt protein expressions, with no change in p-PI3K and p-Akt protein expression quantities. The p-mTOR protein expression decreased with the extension of time, where as the PTEN protein expression showed a time-dependent increase. GNA could inhibit the proliferation of melanoma B16 cells and induce their apoptosis within certain time and concentration ranges. Its mechanism in inducing the cell apoptosis may be related to PI3K/Akt/mTOR signaling pathways.

Myeloid-Derived Suppressor Cells Confer Tumor-Suppressive Functions on Natural Killer Cells via Polyinosinic:Polycytidylic Acid Treatment in Mouse Tumor Models

Polyinosinic:polycytidylic acid (poly I:C), a synthetic double-stranded RNA, acts on myeloid cells and induces potent antitumor immune responses including natural killer (NK) cell activation. Myeloid-derived suppressor cells (MDSCs) systemically exist in tumor-bearing hosts and have strong immunosuppressive activity against antitumor effector cells, thereby dampening the efficacy of cancer immunotherapy. Here we tested what happened in MDSCs in poly I:C-treated mice. NK-sensitive syngenic tumor (B16)-bearing C57BL/6 mice were employed for this study. Intraperitoneal poly I:C treatment induced MDSC activation, driving CD69 expression and interferon (IFN)-γ production in NK cells. IFN-γ directly inhibited proliferation of B16 cells. This NK cell priming led to growth retardation of B16 tumors, although no direct tumoricidal activity was induced in NK cells. Mechanistic analysis using KO mice and function-blocking monclonal antibody revealed that MDSCs produced IFN-α via the mitochondrial antiviral signaling protein (MAVS) pathway after in vivo administration of poly I:C, and activated NK cells through the IFNAR pathway. MDSC-mediated NK cell priming was reconstituted by IFN-α in a coculture system. Either the MAVS or IFNAR signaling pathway was required for activation of MDSCs that led to growth retardation of B16 tumor in vivo. The results infer that MDSC is a target of poly I:C to prime NK cells, which exert antitumor activity to NK-sensitive tumor cells.

Patatin-like PLA&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; with cytotoxicity against mammalian and plant tumour cells

Plants can respond to traumatism by synthesis and secretion of defence molecules. Wound-healing and desiccation stress of pieces of potato tuber parenchyma (Solanum tuberosum) promoted the secretion of a patatin-like phospholipase A2, PLA2 (EC.3.1.1.4.) that displayed cytotoxic activity against tumour cells. The potato secretion product, an oligomeric form of patatin-like protein, was shown to contain several isoforms of PLA2 polypeptides and to be associated with other proteins, including Kunitz-type protease inhibitors. Patatin-like protein secretion was inhibited by vanadate. Secreted patatin-like proteins displayed specific features, such as extracellular function and low molecular weights, mainly 36 to 40 kDa. The 36-kDa polypeptide sequence was related to iPLA2α. Polypeptide spots of secreted patatin-like protein exhibited a nucleotide-binding consensus motif, GGGIKG that has been described in iPLA2 gene family. The cytotoxic agent caused cell death of plant crown-gall induced by Agrobacterium tumefaciens, and inhibited B16 cell proliferation, but at the same concentration did not display any toxicity against non-transformed cells. PLA2 enzyme activity was required for cytotoxicity against B16 melanoma cells. A model for such a specific activity against tumour cells is discussed in connection with asymmetric phospholipid patterns of cell membranes. In conclusion, secreted patatin-like PLA2 (e-patatin) may represent a novel therapeutic target for the development of new agents against cancer.

Antiangiogenic and Antitumoral Effects Mediated by a Vascular Endothelial Growth Factor Receptor 1 (VEGFR-1)-Targeted DNAzyme

Antiangiogenesis is a promising antitumor strategy that inhibits tumor vascular formation to suppress tumor growth. DNAzymes are synthetic single-strand deoxyribonucleic acid (DNA) molecules that can cleave ribonucleic acids (RNAs). Here, we conducted a comprehensive in vitro selection of active DNAzymes for their activity to cleave the vascular endothelial growth factor receptor (VEGFR-1) mRNA and screened for their biological activity in a matrigel tube-formation assay. Among the selected DNAzymes, DT18 was defined as a lead molecule that was further investigated in several model systems. In a rat corneal vascularization model, DT18 demonstrated significant and specific antiangiogenic activity, as evidenced by the reduced area and vessel number in VEGF-induced corneal angiogenesis. In a mouse melanoma model, DT18 was shown to inhibit B16 tumor growth, whereas it did not affect B16 cell proliferation. We further assessed the DT18 effect in mice with established human nasopharyngeal carcinoma (NPC). A significant inhibition of tumor growth was observed, which accompanied downregulation of VEGFR-1 expression in NPC tumor tissues. To evaluate DT18 effect on vasculature, we performed dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) on the human NPC xenograft mice treated with DT18 and showed a reduction of the parameter of K(trans) (volume constant for transfer of contrast agent), which reflects the condition of tumor microvascular permeability. When examining the safety and tolerability of DT18, intravenous administration of Dz18 to healthy mice caused no substantial toxicities, as shown by parameters such as body weight, liver/kidney function, and histological and biochemical analyses. Taken together, our data suggest that the anti-VEGFR-1 DNAzyme may be used as a therapeutic agent for the treatment of cancer, such as NPC.

Development of dextran microparticles loaded with IL-1Ra of high-encapsulation efficiency and high-bioactivity by a novel method without exposing IL-1Ra to water–oil interfaces

Abstract The interleukin-1 receptor antagonist (IL-1Ra), having the potential of treating cancers, has been used for treating rheumatoid arthritis in clinic. To improve its therapeutic efficacy and patient compliance, IL-1Ra was often needed to prepare a long efficacy formulation using all kinds of method for protein stabilization. In this study, we reported a novel freezing-induced PEG water solution phase/dextran water solution phase separation method to prepare the IL-1Ra-loaded dextran microparticles to address stability of IL-1Ra in preparation process for all kinds of formulation, namely: first IL-1Ra was dissolved in water together with dextran and polyethylene glycol, and then by a freezing process during which dextran is separated out as the dispersed phase with IL-1Ra partitioned in dextran microparticles preferentially. The frozen sample was then lyophilized to powder and washed with dichloromethane to remove the PEG continuous phase. Once IL-Ra was loaded in the dextran microparticles, 1–5 μm in diameter, the dextran microparticles gained resistance to oil/water interfaces without IL-Ra aggregation and activity loss. The bioactivity from dextran microparticles in vitro is preserved highly (above 98%), while bioactivity from IL-1Ra-loaded dextran microparticles using the control method of water-in-oil-in-water (W/O/W) method is only 70.5% by inhibiting melanoma B16 cell proliferation. The dextran microparticles may be used further to prepare different formulations according to clinic needs.

Effect of pericytes on epithelial-to-mesenchymal transition in melanoma.

84 Background: Melanoma-associated stroma cells play an important role in supporting cancer cell proliferation, invasion, and dissemination. Increased invasiveness has been observed in cancer cells undergoing epithelial-to-mesenchymal transition (EMT); however, it is unknown whether EMT is facilitated by stroma cells. We showed that pericytes constitute a predominant stroma subpopulation that promotes melanoma growth by interacting with cancer cells. This study investigates the mechanism by which pericytes facilitate melanoma development. Methods: GFP+ pericytes isolated from tumors and adipose tissue were co-cultured in vitro with B16 melanoma cells at a 3:1 ratio. After 4 days, proliferation of B16 cells and pericytes was assessed. Also, co-cultures were labeled for several markers and analyzed by flow cytometry (FC). Tumorigenicity was investigated by isolating B16 cells from co-cultures by FACS sorting and then injected into SCID mice to measure tumor growth. Results: B16 cells induced pericyte differentiation into FAP+ myofibroblasts. However, no change in the pericyte proliferation rate was observed. B16 cells co-cultured with pericytes, and later separated by FACS sorting, displayed faster proliferation rates in vitro, and induced increased tumor growth rates when injected into SCID mice, compared with naive B16 cells. Pericytes increased B16 cell proliferation rate and induced a change in cell morphology, from cobblestone to fibroblast-like colonies. Interaction between B16 cells and pericytes in co-culture increased pericyte production of TGF-β and increased the expression of the stem cell markers SSEA-1, OCT3/4 and CD271 in B16 cells. In addition, cadherin switching, demonstrated by loss of E-cadherin expression and an up-regulation of the mesenchymal markers N-cadherin and vimentin was observed in B16 cells. Conclusions: Pericyte production of TGF-β promotes B16 cell development of EMT, as shown by loss of E-cadherin expression and up-regulation of the mesenchymal markers N-cadherin and vimentin, resulting in an increase in melanoma cell tumorigenicity. These results suggest that therapies targeting stromal pericytes may be a promising approach for melanoma treatment.

Effect of pericytes on melanoma development.

83 Background: Melanoma-associated stroma cells regulate tumor establishment, invasion, and dissemination through paracrine and heterotypic cell-cell interactions with cancer cells. Pericytes constitute a major noninflammatory component of the melanoma-associated stroma. Our study is designed to evaluate the role of pericytes in melanoma development. Methods: Tumors induced in GFP+/SCID mice with GFP-B16 cells were harvested after 14 days, enzyme digested, labeled against mesenchymal markers, and analyzed by flow cytometry (FC). The distribution of stromal subpopulations in tumors was investigated by immunofluorescence microscopy (IFM). Stromal pericytes from tumors and adipose tissue were FACS sorted, mixed with B16 cells at a 3:1 ratio, and injected into SCID mice. Tumor diameters were taken periodically with a scientific caliper, and used to determine tumor volumes using the ellipsoid formula. Results: FC analysis showed that the melanoma stroma was composed of CD45+ inflammatory cells, CD31+ endothelial cells, FAP+ myofibroblasts and CD146+ cells. IFM analysis showed that the CD146+ cells are perivascular CD31-/CD34-/α-SMA+ stromal pericytes that associated with TGF-β immunoreactive CD271+/CD146+B16 cells in perivascular tumor niches. Co-induction experiments were performed to investigate the effect of pericytes on melanoma development. We observed faster growth rates in the size of tumors co-induced with pericytes, compared with tumors induced with B16 cells alone. These co-induced tumors had bigger masses, more volume, were hypercellular, and had increase vascularization compared with control tumors. In addition, pericytes increased the B16 cell proliferation rate, as determined by higher expression of Ki-67 in the tumor fraction of co-induced tumors. Conclusions: Pericytes promote melanoma development by inducing angiogenesis and melanoma cell proliferation. Our results suggest that pericytes could be utilized as a therapeutic target for melanoma treatment.

Fucose-Containing Sulfated Polysaccharides from Brown Seaweeds Inhibit Proliferation of Melanoma Cells and Induce Apoptosis by Activation of Caspase-3 in Vitro

Fucose-containing sulfated polysaccharides (FCSPs) extracted from seaweeds, especially brown macro-algae, are known to possess essential bioactive properties, notably growth inhibitory effects on tumor cells. In this work, we conducted a series of in vitro studies to examine the influence of FCSPs products from Sargassum henslowianum C. Agardh (FSAR) and Fucus vesiculosus (FVES), respectively, on proliferation of melanoma B16 cells and to investigate the underlying apoptosis promoting mechanisms. Cell viability analysis showed that both FCSPs products, i.e., FSAR and FVES, decreased the proliferation of the melanoma cells in a dose-response fashion, with FSAR being more potent at lower dosages, and FVES being relatively more anti-proliferative than FSAR at higher dosages. Flow cytometric analysis by Annexin V staining of the melanoma cells exposed to the FCSPs products confirmed that both FSAR and FVES induced apoptosis. The FCSPs-induced apoptosis was evidenced by loss of plasma membrane asymmetry and translocation of the cell membrane phospholipids and was accompanied by the activation of caspase-3. The FCSPs bioactivity is proposed to be attributable to distinct structural features of the FCSPs, particularly the presence of sulfated galactofucans (notably in S. henslowianum) and sulfated fucans (notably in F. vesiculosus). This study thus indicates that unfractionated FCSPs may exert bioactive effects on skin cancer cells via induction of apoptosis through cascades of reactions that involve activation of caspase-3.

MicroRNA miR-21 Regulates the Metastatic Behavior of B16 Melanoma Cells

MicroRNA-21 (miR-21) is overexpressed in many human tumors and has been linked to various cellular processes altered in cancer. miR-21 is also up-regulated by a number of inflammatory agents, including IFN, which is of particular interest considering the close relationship between inflammation and cancer. Because miR-21 appears to be overexpressed in human melanoma, we examined the role of miR-21 in cancer development and metastasis in B16 mouse melanoma cells. We found that miR-21 is a member of an IFN-induced miRNA subset that requires STAT3 activation. To characterize the role of miR-21 in melanoma behavior, we transduced B16 cells with lentivirus encoding a miR-21 antagomir and isolated miR-21 knockdown B16 cells. miR-21 knockdown or IFN treatment alone inhibited B16 cell proliferation and migration in vitro, and in combination they had an enhanced effect. Moreover, miR-21 knockdown sensitized B16 cells to IFN-induced apoptosis. In B16 cells miR-21 targeted tumor suppressor (PTEN and PDCD4) and antiproliferative (BTG2) proteins. To characterize the role of miR-21 in vivo, empty vector- and antagomiR-21-transduced B16 melanoma cells were injected via tail vein into syngeneic C57BL/6 mice. Although empty vector-transduced B16 cells produced large lung metastases, miR-21 knockdown cells only formed small lung lesions. Importantly, miR-21 knockdown tumor-bearing mice exhibited prolonged survival compared with empty vector tumor-bearing mice. Thus, miR-21 regulates the metastatic behavior of B16 melanoma cells by promoting cell proliferation, survival, and migration/invasion as well as by suppressing IFN action, providing important new insights into the role of miR-21 in melanoma.

MicroRNA cloning and sequencing in osteosarcoma cell lines: differential role of miR-93

Studies show that abnormalities in non-coding genes can contribute to carcinogenesis; microRNA levels may modulate cancer growth and metastatic diffusion. MicroRNA libraries were built and sequenced from two osteosarcoma cell lines (MG-63 and 143B), which differ in proliferation and transmigration. By cloning and transfection, miR-93, expressed in both cell lines, was then investigated for its involvement in osteosarcoma progression. Six of the 19 miRNA identified were expressed in both cell lines with higher expression levels of miR-93 in 143B and in primary osteosarcoma cultures compared to normal osteoblasts. Interestingly, levels of miR-93 were significantly higher in metastases from osteosarcoma than in paired primary tumours. When 143B and MG-63 were transfected with miR-93, clones appeared to respond differently to microRNA overexpression. Ectopic expression of miR-93 more significantly increased cell proliferation and invasivity in 143B than in MG-63 clones. Furthermore, increased mRNA and protein levels of E2F1, one of the potential miR-93 targets, were seen in osteosarcoma cellular clones and its involvement in 143B cell proliferation was confirmed by E2F1 silencing. Although further studies are needed to evaluate miRNA involvement in osteosarcoma progression, miR-93 overexpression seems to play an important role in osteosarcoma cell growth and invasion.

Effect of zibuganshenfang on the expression and activity of tyrosinase on B16 cells

ZiBuGanShenFang (ZBGSF) is a traditional herbal formula, which has showed an outstanding therapeutic effect on vitiligo clinically. Our aim is to investigate the influence of ZBGSF drug serum on the expression and activity of Tyrosinase in B16 cells, explore the mechanism of ZBGSF on Vitiligo treatment further. tyrosinase activity was measured by zymological methods, western blotting and RT-PCR were used to measure the protein content and mRNA level of tyrosinase and related proteins, respectively. ZBGSF drug serum had no effect on the proliferation of B16 cells. But it could promote Tyrosinase activity significantly and increase protein content and mRNA level of tyrosinase and related proteins in B16 cells. Promoting the expression of tyrosinase protein and mRNA may be the elementary basis of ZBGSF on Vitiligo treatment.

Ginsenoside F1 Modulates Cellular Responses of Skin Melanoma Cells

Ginsenoside (G)-F1 is an enzymatic metabolite generated from G-Rg1. Although this metabolite has been reported to suppress platelet aggregation and to reduce gap junction-mediated intercellular communication, the modulatory activity of G-F1 on the functional role of skin-derived cells has not yet been elucidated. In this study, we evaluated the regulatory role of G-F1 on the cellular responses of B16 melanoma cells. G-F1 strongly suppressed the proliferation of B16 cells up to 60% at 200 <TEX>${\mu}g/mL$</TEX>, while only diminishing the viability of HEK293 cells up to 30%. Furthermore, G-F1 remarkably induced morphological change and clustering of B16 melanoma cells. The melanin production of B16 cells was also significantly blocked by G-F1 up to 70%. Interestingly, intracellular signaling events involved in cell proliferation, migration, and morphological change were up-regulated at 1 h incubation but down-regulated at 12 h. Therefore, our results suggest that G-F1 can be applied as a novel anti-skin cancer drug with anti-proliferative and anti-migration features.

Endothelial cell-expressed Tim-3 facilitates metastasis of melanoma cells by activating the NF-κB pathway

T cell immunoglobulin and mucin domain-3 (Tim-3) is originally recognized as a receptor of Th1 cells. We found that Tim-3 could be expressed in endothelial cells after stimulation with tumor cell-released TLR4 ligand. Tim-3 expressed by endothelial cells does not function as the receptor of galectin-9, but mediates the interaction of endothelial cells with tumor cells. The engagement of endothelial cell-expressed Tim-3 with a non-galectin 9 putative receptor on B16 melanoma cells could trigger the NF-kappaB signaling pathway in B16 cells. The activated NF-kappaB not only promoted the proliferation of B16 cells, but also enhanced apoptosis resistance of B16 cells by up-regulating Bcl-2 and Bcl-xL and down-regulating Bax. Consistently, Tim-3 facilitated the survival of B16 cells in the blood stream, arrested in the lung and following invasion, resulted in more metastatic nodules in the lung. These findings suggest that endothelial cell-expressed Tim-3 increases tumor cell metastatic potential by facilitating tumor cell intravasation, survival in blood stream and extravasation. Thus, anti-inflammation or blockade of Tim-3 may contribute to the prevention of metastasis.

Abstract 1499: Gene therapy in a mouse model for malignant melanoma: Combining the activities of the p53/Arf and interferon pathways

Abstract Background: Malignant melanoma cells typically maintain wild-type p53 in a non-functional state, due in part to the loss of ARF (p14ARF in humans, p19ARF in mice). Data have shown that interferon-β (IFNβ) can activate the transcription of p53 and interact with the ARF pathway as well. By using a p53-driven adenovirus, we sought to combine the action and regulation of p53, p19ARF and IFNβ for the treatment of malignant melanoma in an immunocompetent mouse model. Methods: p53-responsive AdPG adenoviral vectors (Bajgelman and Strauss, 2008) containing p53, p19ARF and IFNβ were produced and expression verified by immunofluorescence and ELISA. In vitro evaluation of the antiproliferative effect of single or co-transduction of B16F10 cells (B16, p53 wild-type) was done by FACS after annexin/PI staining. C57/Bl6 mice were injected subcutaneously with B16 cells and tumors were allowed to develop (∼0.5 cm2). At this point, three consecutive intra-tumor injections (3 day interval between injections) of individual or combined adenoviral vectors were performed. Animals were then sacrificed and tumors collected and analyzed. Results: The combination of IFNβ and p19ARF proved to be more effective in inhibiting proliferation of B16 cells than either treatment alone, both in vitro and in vivo. In vitro we observed that neither AdPGp19 nor AdPGIFNβ alone altered the cell cycle, though co-transduction with these vectors resulted in extensive cell death. Annexin-V staining was also increased by the combined, but not individual, treatments. Cell death was observed only after 90-120h of incubation, yet prior to this event, indicators of senescence (positive SA-βGal staining, loss of histone H3 acetylatation at Lys9) were revealed in both single and combined vector treatments. In vivo, we observed that the combined gene transfer strategy led to reduced tumor volume, reduced incorporation of BrdU and increased staining by TUNEL in the primary tumor. Assays are in progress to determine if the combined treatment is effective in reducing metastases and prolonging survival. Conclusion: The use of p53-responsive vectors for the restoration of ARF expression in the presence of IFNβ represents a potential strategy for melanoma tumor suppression. While mechanistic studies are underway, we propose that the complementation of the p53/ARF and interferon pathways in the primary tumor may lead to reduction of metastases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1499.

The antitumor properties of a nontoxic, nitric oxide–modified version of saquinavir are independent of Akt

Application of the HIV protease inhibitor saquinavir (Saq) to cancer chemotherapy is limited by its numerous side effects. To overcome this toxicity, we modified the original compound by covalently attaching a nitric oxide (NO) group. We compared the efficacy of the parental and NO-modified drugs in vitro and in vivo. The novel compound saquinavir-NO (Saq-NO) significantly reduced the viability of a wide spectrum of human and rodent tumor cell lines at significantly lower concentration than the unmodified drug. In contrast to Saq, Saq-NO had no effect on the viability of primary cells and drastically reduced B16 melanoma growth in syngeneic C57BL/6 mice. In addition, at the equivalent of the 100% lethal dose of Saq, Saq-NO treatment caused no apparent signs of toxicity. Saq-NO blocked the proliferation of C6 and B16 cells, up-regulated p53 expression, and promoted the differentiation of these two cell types into oligodendrocytes or Schwann-like cells, respectively. Although it has been well documented that Saq decreases tumor cell viability by inhibiting Akt, the anticancer properties of Saq-NO were completely independent of the phosphatidylinositol 3-kinase/Akt signaling pathway. Moreover, Saq-NO transiently up-regulated Akt phosphorylation, delivering a protective signal that could be relevant for primary cell protection and the absence of drug toxicity in vivo. It was unlikely that released NO was independently responsible for these drug effects because Saq-NO treatment increased intracellular and secreted NO levels only slightly. Rather, the chemical modification seems to have produced a qualitatively new chemical entity, which may have a unique mode of action against cancer cells.

Inhibitory activity of Bifidobacterium adolescent combined with cisplatin on melanoma in mice and its mechanism

The aim of this study is to explore inhibitory activity of Bifidobacterium adolescent combined with cisplatin on the growth of melanoma (B16) in mice and the underlying mechanism. C57 mice were inoculated with B16 cancer cells to construct mouse model of melanoma and treated with bifidobacterium adolescent combined with cisplatin. Ratios of inhibitory activity on the growth of melanoma (B16) were calculated. Pathology changes of the tumor were observed by HE staining. B16 cell cycles were examined on a flow cytometer. Lymphocyte proliferation was measured with MTT assay and the T-cell subset was measured by double marked fluorescence. When bifidobacterium of 1010 cfu/L was injected, the ratio of inhibitory activity on the growth of melanoma (B16) reached 54%, which was similar to that of cisplatin group. The ratio of inhibitory activity reached 74.45% when the mice were treated by bifidobacterium combined with cisplatin. HE staining shows that bifidobacterium inhibited B16 cell proliferation and enhanced the cisplatins killing activity on B16 cells. The results of flow cytometry demonstrated that B16 cell proliferation was arrested at G1 stage after treatment with bifidobacterium. The B16 cell proliferation was arrested at S stage after treatment with cisplatin. The CD4+ percentage increased and the difference was significant compared with the normal group after treatment with bifidobacterium, indicating that T-cell immune activity was enhanced. Treatment with bifidobacterium combined with cisplatin can enhance the inhibitory activity on the growth of melanoma (B16) of cisplatin. The mechanism of the inhibitory activity on B16 cell proliferation is correlated with the enhanced immune activity in mice.