Melanotransferrin induces human melanoma SK-Mel-28 cell invasion in vivo

The expression of melanotransferrin (MTf), a membrane-bound glycoprotein highly expressed in melanomas, is correlated with tumor vascularization and progression, suggesting a proinvasive function associated with MTf in malignant tumors. To test this hypothesis, we silenced MTf in human melanoma SK-MEL-28 cells using small interfering RNA (siRNA) and examined the plasmin activity and invasiveness of MTf-silenced melanoma. In vitro, the siRNA-mediated MTf knockdown inhibited by 58% the cell surface activation of plasminogen into plasmin. In addition, decreased expression of MTf in melanoma cells reduced cell migration. In vivo, we used a nude mice invasion model in which tissue factor (TF) induces vascular [125I]-fibrin deposition following injection. Using this metastasis model, the invasive potential of MTf-silenced cells into the lungs was reduced by fivefold. Altogether, these findings strongly suggest that MTf overexpression in melanoma cells contributes to tumor progression by stimulating plasmin generation as well as cell migration and invasion.     

Transforming growth factor-beta3 increases the invasiveness of endometrial carcinoma cells through phosphatidylinositol 3-kinase-dependent up-regulation of X-linked inhibitor of apoptosis and protein kinase c-dependent induction of matrix metalloproteinase-9

Tumor cells often acquire intrinsic resistance to the growth inhibitory and pro-apoptotic effects of transforming growth factor-beta (TGF-beta); moreover, TGF-beta can confer invasive properties to established tumor cells. In the present study, we show that TGF-beta isoforms (TGF-beta1, TGF-beta2, and TGF-beta3) trigger proper Smad signaling in human endometrial carcinoma cell lines and efficiently inhibit cellular proliferation. These cells, however, exhibit a high degree of resistance to TGF-beta pro-apoptotic effects; we found that this resistant phenotype would be acquired through up-regulation of X-linked inhibitor of apoptosis protein (XIAP) levels. In addition, using RNA interference and pharmacological inhibitors, we show that TGF-beta increases cellular invasiveness via two distinct signaling pathways in endometrial carcinoma cells: phosphatidylinositol 3-kinase/AKT-dependent up-regulation of XIAP and protein kinase C-dependent induction of matrix-metalloproteinase-9 (MMP-9) expression. Additionally, these findings were correlated with clinical observations showing abundant TGF-beta immunoreactivity in human endometrial carcinoma tumors in vivo, extending from the epithelial compartment to the stroma upon acquisition of an invasive phenotype (gradually from grades I to III). Collectively our results describe for the first time a role for TGF-beta3 in tumor invasiveness.     

A novel series of potent cytotoxic agents targeting G2/M phase of the cell cycle and demonstrating cell killing by apoptosis in human breast cancer cells

Breast cancer, a leading cause of mortality in women, warrants the development and biological evaluation of new anticancer agents. A novel series of thiopyridine triazine derivatives was synthesized and investigated in the human breast cancer cell line, MDA-MB-468. SM40, the most potent derivative, induced a G2/M arrest and apoptosis with a possible involvement of p53. The cytotoxicity of SM40 was also examined against the NCI 60 cell line panel and its potency was rationalized using molecular modeling. Results suggest that SM40 is a promising cytotoxic agent.     

A new platinum complex of triazine demonstrates G1 arrest with novel biological profile in human breast cancer cell line, MDA-MB-468

A novel class of platinum(II) complexes of pyridine sulfide derivatives of triazine was synthesized, characterized, and investigated using the human breast cancer cell line, MDA-MB-468. S-30 was one of the most potent derivatives of its class (IC(50), 0.39 microM) eliciting the greatest biological response. S-30 induced arrest in the G1 phase and apoptosis (TUNEL assay) in a p53/p21(WAF1/CIP1)-consistent manner. Modeling and docking experiments were performed for three known targets for cisplatin, d(GpG), d(ApG), and a protein (Cu/Zn superoxide dismutase, SOD) from bovine origin. A Blast search of bovine SOD was performed to identify analogous human protein targets resulting in about 22 human proteins. A multi-sequence alignment of those targets showed >80% sequence identity and >88% similarity. One of them is SOD1 that is differentially expressed (based on global gene expression pattern) in various forms of cancer and other diseases. SOD1 controls apoptosis via p53/BAD/BAX/BCL2 in the amyotrophic lateral sclerosis (ALS) pathway and is also involved in various other KEGG's pathways. Results suggest that the S-30 is a potential cytotoxic agent.     

Reproductive potential of balsam fir (Abies balsamea), white spruce (Picea glauca), and black spruce (P. mariana) at the ecotone between mixedwood and coniferous forests in the boreal zone of western Quebec

The reproductive potentials of balsam fir and white spruce (co-dominants in mixedwood forests) and black spruce (dominant in coniferous forests) were studied to explain the location of the ecotone between the two forest types in the boreal zone of Quebec. Four sites were selected along a latitudinal gradient crossing the ecotone. Cone crop, number of seeds per cone, percentage filled seeds, and percentage germination were measured for each species. Balsam fir and white spruce cone crops were significantly lower in the coniferous than in the mixedwood forest, while black spruce had greater crop constancy and regularity between both forest types. Mast years were more frequent for black spruce than for balsam fir in both forest types (mast year data not available for white spruce). The number of seeds per cone was more related to cone size than to forest type for all species. Black spruce produced more filled seeds in the coniferous forest than balsam fir or white spruce. The sum of growing degree-days and the maximum temperature of the warmest month (both for the year prior to cone production) significantly affected balsam fir cone production. The climate-related northward decrease in reproductive potential of balsam fir and white spruce could partly explain the position of the northern limit of the mixedwood forest. This could change drastically, however, as the ongoing climate warming might cancel this competitive advantage of black spruce.     

Prostate apoptosis response-4 mediates TGF-β-induced epithelial-to-mesenchymal transition

A growing body of evidence supports that the epithelial-to-mesenchymal transition (EMT), which occurs during cancer development and progression, has a crucial role in metastasis by enhancing the motility of tumor cells. Transforming growth factor-β (TGF-β) is known to induce EMT in a number of cancer cell types; however, the mechanism underlying this transition process is not fully understood. In this study we have demonstrated that TGF-β upregulates the expression of tumor suppressor protein Par-4 (prostate apoptosis response-4) concomitant with the induction of EMT. Mechanistic investigations revealed that exogenous treatment with each TGF-β isoform upregulates Par-4 mRNA and protein levels in parallel levels of phosphorylated Smad2 and IκB-α increase. Disruption of TGF-β signaling by using ALK5 inhibitor, neutralizing TGF-β antibody or phosphoinositide 3-kinase inhibitor reduces endogenous Par-4 levels, suggesting that both Smad and NF-κB pathways are involved in TGF-β-mediated Par-4 upregulation. NF-κB-binding sites in Par-4 promoter have previously been reported; however, using chromatin immunoprecipitation assay we showed that Par-4 promoter region also contains Smad4-binding site. Furthermore, TGF-β promotes nuclear localization of Par-4. Prolonged TGF-β3 treatment disrupts epithelial cell morphology, promotes cell motility and induces upregulation of Snail, vimentin, zinc-finger E-box binding homeobox 1 and N-Cadherin and downregulation of Claudin-1 and E-Cadherin. Forced expression of Par-4, results in the upregulation of vimentin and Snail expression together with increase in cell migration. In contrast, small interfering RNA-mediated silencing of Par-4 expression results in decrease of vimentin and Snail expression and prevents TGF-β-induced EMT. We have also uncovered a role of X-linked inhibitor of apoptosis protein in the regulation of endogenous Par-4 levels through inhibition of caspase-mediated cleavage. In conclusion, our findings suggest that Par-4 is a novel and essential downstream target of TGF-β signaling and acts as an important factor during TGF-β-induced EMT.     

Synthesis and cytotoxic activity of benzopyran-based platinum(II) complexes

A series of benzopyran-based platinum complexes of types 4 and 5 were synthesized as potential anticancer agents. The novel compounds were synthesized in several steps using simple and efficient chemistry. The newly synthesized compounds were evaluated for their biological efficacy and showed significant in vitro cytotoxic activity in different hormone-dependent and -independent breast cancer cell lines. Docking and other molecular modeling experiments were also performed for one of the potent compounds, 5f, which showed that both the possible enantiomeric forms (5f with 3R,4R and 5f with 3S,4S) of the molecule have comparable lowest energy (for 5f with 3R,4R, −31.953 kcal/mol and for 5f with 3S,4S, −31.944 kcal/mol). The 3D QSAR was examined for the derivatives of both enantiomeric forms and a novel relationship for the 3S,4S derivatives is discussed.