M. Filomena Botelho

Chiral 6,7-bis(hydroxymethyl)-1H,3H-pyrrolo[1,2-c]thiazoles with anti-breast cancer properties.

The synthesis and biological evaluation of 6,7-bis(hydroxymethyl)-1H,3H-pyrrolo[1,2-c]thiazoles as anticancer agents against MCF7 breast cancer cell lines is reported. The design of the new compounds has been guided considering (3R)-6,7-bis(hydroxymethyl)-5-methyl-3-phenyl-1H,3H-pyrrolo[1,2-c]thiazole as the lead compound due to its good performance against MCF7 breast cancer cell lines (IC(50) = 1.0 μM). The structural changes included the removal of the phenyl group at C-3, the replacement of this group by a 3,4,5-trimethoxyphenyl group, the removal of the methyl group at C-5 from the lead scaffold and the replacement of this group by a phenyl substituent. Overall, these studies showed that the combined presence of a phenyl group at C-3 and a methyl group at C-5 in the 1H,3H-pyrrolo[1,2-c]thiazole ring system is essential to ensure high cytotoxicty against MCF7 breast cancer cell lines. To probe whether the absolute configuration of the lead compound might affect the anticancer activity, its enantiomer was prepared and the activity against MCF7 cells was evaluated. (3S)-6,7-Bis(hydroxymethyl)-5-methyl-3-phenyl-1H,3H-pyrrolo[1,2-c]thiazole proved to be the most active compound so far studied, with IC(50) value of 0.5 μM.

P-glycoprotein Versus MRP1 on Transport Kinetics of Cationic Lipophilic Substrates: A Comparative Study Using [99mTc]Sestamibi and [99mTc]Tetrofosmin

The multidrug resistance (MDR) phenotype in cancer is closely related with the overexpression of P-glycoprotein (Pgp) and multidrug resistance protein-1 (MRP1). Although conferring resistance to a similar spectrum of drugs, these proteins present distinct transport mechanisms and have their own substrates. In this work, we compared the functional properties of Pgp and MRP1 in the transport kinetics of two cationic lipophilic tracers, [(99m)Tc]sestamibi and [(99m)Tc]tetrofosmin, in cellular models of resistance. Cellular transport kinetics of both tracers was evaluated in Small-cell lung cancer cell line H69 and in its drug-resistant sublines, H69LX4 and H69AR, overexpressing Pgp and MRP1, respectively. Studies were performed in the absence and in the presence of MDR modulators. Kinetic parameters extracted from time-activity curves were analyzed through receiver-operating characteristics curve analysis. The uptake and the efflux rate of both radiotracers were significantly higher (p < 0.05) in sensitive cells. However, MRP1 was more effective than Pgp in removing tracers from the intracellular medium. The addition of verapamil and PSC833 significantly reduced the efflux rate and restored the accumulation of both tracers in H69LX4 cells. Only verapamil was effective in the inhibition of MRP1; however, the effects were more pronounced with [(99m)Tc]sestamibi, when compared to [(99m)Tc]tetrofosmin. Outward transport of radiotracers by MRP1 was dependent on the intracellular glutathione levels. We concluded that both tracers can detect Pgp- and MRP1-mediated drug resistance, based on transport kinetics; however, MRP1 is more effective than Pgp on outward transport of radiotracers. We postulate that this finding can be useful to distinguish between the two resistance mechanisms.

Synthesis of new 2-galactosylthiazolidine-4-carboxylic acid amides. Antitumor evaluation against melanoma and breast cancer cells.

A set of 2-galactosylthiazolidine-4-carboxylic acid amides was synthesized with different length for the carbon chain amide moiety. The cytotoxicity of the molecules was evaluated against A375 melanoma and MCF7 breast cancer cell lines. For the derivatives tested, the one that contains a C(16) amide carbon chain is the most active with an IC(50) of 17.0 μM for A375 and 5.8 μM for MCF7. This compound also shows cytotoxicity in the triple negative cancer cell line HCC1806. The selectivity of the compounds was assessed by comparing the cytotoxicity in cancer cell line versus in a fibroblast cell line. Flow cytometry studies show the activation of apoptotic pathways and also DNA damages with blockage of the cell cycle in the S-phase and appearance of peaks in G0/G1-phase.

Novel 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine fused chlorins as very active photodynamic agents for melanoma cells.

The development of new stable 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused chlorins with high absorption properties at 650 nm, and their impressive photosensitizer ability against melanotic and amelanotic cancer cells is described. Comparison between a diester-substituted chlorin with the corresponding dihydroxymethyl derivative demonstrated that the increased hydrophilicity of the latter is crucial to ensure nanomolar activity against melanoma cells. The new photosensitizer leads to death of human melanoma cells being both apoptosis and necrosis in equal parts involved in the treatment response. The dihydroxymethyl-chlorin was particularly active against human melanocytic melanoma A375 cells, which can be viewed as a solution to overcome the resistance of melanotic melanoma to photodynamic therapy.

In vivo biodistribution of antihyperglycemic biopolymer-based nanoparticles for the treatment of type 1 and type 2 diabetes

Graphical abstract Biodistribution of insulin‐loaded alginate/dextran sulfate‐based nanoparticles dual coated with chitosan and 99mTc‐albumin after oral administration. The comparison of the oral antihyperglycemic effect between type 1 and type 2 diabetic models after the intraperitoneal glucose tolerance test revealed that the effect lasted longer in the type 1 model and that the glycemia increased to a greater extend in the type 2 model. No caption available. Abstract This study aimed to assess the biodistribution of antihyperglycemic insulin‐loaded alginate/dextran sulfate‐based nanoparticles dual coated with chitosan and technetium‐99m‐albumin (99mTc‐BSA) after oral administration. The oral administration of 50 IU/kg insulin‐loaded nanoparticles to type 1 diabetic rats showed prolonged antihyperglycemic effects up to 12 h and relative pharmacological availability of 5.04% comparing to the subcutaneous administration. The oral antihyperglycemic effect was further compared between type 1 and type 2 diabetic models by the intraperitoneal glucose tolerance test, revealing that the effect lasted longer in the type 1 diabetic model. 99mTc‐BSA revealed to be a good nanoparticles’ tracer since there was no systemic absorption and 99mTc‐BSA‐nanoparticles were capable of increasing their residence time in the intestinal epithelium of balb‐c mice when compared with 99mTc‐BSA biodistribution. Thus, this biopolymeric‐based delivery nanoparticulate system is a promising tool for the therapy of type 1 and type 2 diabetic individuals and prevention of T1D.

Platinum(II) Ring-Fused Chlorins as Near-Infrared Emitting Oxygen Sensors and Photodynamic Agents

Novel near-infrared luminescent compounds based on platinum(II) 4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine-fused chlorins are described. These compounds have high photostability and display light emission, in particular simultaneous fluorescence and phosphorescence emission in solution at room temperature, in the biologically relevant 700-850 nm red and near-infrared (NIR) spectral region, making them excellent materials for biological imaging. The simultaneous presence of fluorescence and phosphorescence emission at room temperature, with the phosphorescence strongly quenched by oxygen whereas fluorescence remains unaffected, allows these compounds to be used as ratiometric oxygen sensors in chemical and biological media. Both steady-state (fluorescence vs phosphorescence intensities) and dynamic (dependence of phosphorescence lifetimes upon oxygen concentration) luminescence approaches can be used. Photocytotoxicity studies against human melanocytic melanoma cells (A375) indicate that these compounds display potential as photosensitizers in photodynamic therapy.

Osteosarcoma contains a subpopulation of cancer stem-like cells that are highly resistant to radiotherapy

Methods The isolation of CSCs was performed using the sphere formation assay in serum-free medium in non-adherent conditions. The cells were characterized for the expression of mesenchymal stem cell markers (CD90/ CD105/CD73) by flow cytometry. MNNG/HOS and CSCs were irradiated with X-rays at different doses (020Gy). The sensitivity to ionizing radiation was evaluated using the MTT assay after 7 days. Cell-cycle responses were studied at 24h post-irradiation using propidium iodide staining.

Intestinal Epithelial Stem Cells: Distinct Behavior After Surgical Injury and Teduglutide Administration

ABSTRACT Background: Previous studies suggest that intestinal epithelial stem cells (IESC), critical drivers of homeostasis and regeneration, include two subpopulations: crypt-based columnar and “position +4” stem cells, identified by Lgr5 and Bmi1 biomarkers, respectively. Teduglutide is an enterotrophic counterpart of glucagon-like peptide 2. This study aimed to investigate the response of putative IESC to surgical injury and teduglutide administration on an animal model of intestinal resection and anastomosis. Methods: Wistar rats (n = 59) were distributed into four groups: “Ileal Resection” versus “Laparotomy”, subsequently subdivided into “Postoperative Teduglutide Administration” versus “No Treatment”; and sacrificed at third or seventh days, with ileal sample harvesting. Flow cytometry was used to analyze epithelial stem cells with monoclonal antibodies against Lgr5, Bmi1 and also CD44, CD24, CD166, and Grp78 surface markers. Results: Surgical trauma induced an increase of epithelial stem cells population at third day (9.0 ± 0.3 versus 5.7 ± 0.3%, p = 0.0001), which was more intense and involved all subpopulations after ileal resection. At seventh day, teduglutide was significantly associated with higher proportion of Lgr5+/Bmi1− cells (5.8 ± 0.1 versus 2.9 ± 0.3%, p = 0.005) and, on the contrary, lower percentage of Lgr5−/Bmi1+ cells (0.03 ± 0.01 versus 1.9 ± 0.1%, p = 0.049) after ileal resection; and higher proportion of Lgr5+/Bmi1+ cells (1.7 ± 0.1 versus 1.1 ± 0.2%, p = 0.028) after isolated laparotomy. After surgery, Lgr5+/Bmi1− and Lgr5−/Bmi1+ subpopulations demonstrated an inverse correlation and both correlated negatively with Grp78 labeling index. Lgr5−/Bmi1+ and CD44+/CD24low/CD166+/Grp78+ cells proportions exhibited a high grade positive correlation. Conclusion: Those observations support the existence of two epithelial stem cells subpopulations with distinct behavior after surgical injury and teduglutide treatment.

Stroma-derived IL-6, G-CSF and Activin-A mediated dedifferentiation of lung carcinoma cells into cancer stem cells.

Cancer stem cells (CSCs) are a small population of resistant cells inhabiting the tumors. Although comprising only nearly 3% of the tumor mass, these cells were demonstrated to orchestrate tumorigenesis and differentiation, underlie tumors’ heterogeneity and mediate therapy resistance and tumor relapse. Here we show that CSCs may be formed by dedifferentiation of terminally differentiated tumor cells under stress conditions. Using a elegant co-culture cellular system, we were able to prove that nutrients and oxygen deprivation activated non-malignant stromal fibroblasts, which in turn established with tumor cells a paracrine loop mediated by Interleukine-6 (IL-6), Activin-A and Granulocyte colony-stimulating factor (G-CSF), that drove subsequent tumor formation and cellular dedifferentiation. However, by scavenging these cytokines from the media and/or blocking exosomes’ mediated communication it was possible to abrogate dedifferentiation thus turning these mechanisms into potential therapeutic targets against cancer progression.

Photodynamic therapy on bladder cancer cells: further studies on the performance of Coimbra sensitizers

Following previous studies where we developed some high performance porphyrin derivatives for photodynamic therapy demonstrating their activity in different cell lines, we now extend our attention to CRL1472 bladder cancer line. In this work the phototoxicity of several diaryl and tetraarylporphyrins with different structures were evaluated with different incubation times. The phototoxicity observed was not directly related to the concentration of photosensitizer inside cells. Uptake studies demonstrate that the brominated derivative 2 which despite the most efficient photosensitizer presents a poor tendency to enter into cells.