Synthesis of N-acyl Derivatives of Aminocombretastatin A-4 and Study of their Interaction with Tubulin and Downregulation of c-Myc.

BACKGROUND: Six N-acyl derivatives of aminocombretastatin A-4 have been synthesized and evaluated according to their interaction with tubulin and as c-Myc downregulators. AIMS: In search of new promising anti-cancer agents. OBJECTIVE: This study is focused on the synthesis and the biological evaluation of N-acyl derivatives of aminocombretastatin A-4 (CA-4). Docking studies were carried out to find out whether the synthetic derivatives could bind to tubulin at the colchicine site in a conformation similar to that of CA- 4. The synthetic derivatives' effect on the proliferation of several cancer cells and non-cancer cells has been measured. Their effect on tubulin polymerization, cell cycle distribution, the microtubule network and c-Myc expression has also been evaluated. METHODS: A set of six N-acyl derivatives was achieved by means of a peptide-type coupling of aminocombretastatin A-4 and the corresponding carboxylic acid. The synthetic compounds' ability to inhibit cell proliferation was measured by MTT assay against three human carcinoma cell lines (colorectal HT-29, lung A549, and breast adenocarcinoma MCF-7) and one non-tumor cell line (HEK- 293). Turbidimetry time-course measurements evaluated the inhibition of tubulin polymerization. The action of the synthetic derivatives on cell cycle distribution was measured by flow cytometry and their effects on the microtubule network were determined by immunofluorescence microscopy. Finally, the downregulation of the synthetic derivatives on c-Myc protein was quantified by ELISA assay, while the effect on c-Myc gene was measured by RT-qPCR analysis. RESULTS: Derivatives bearing pentanoyl (compound 2), hexanoyl (compound 3), and heptanoyl (compound 4) side chains show anti-proliferative activities on the HT-29 line in the low nanomolar range, with values similar to that exhibited by AmCA-4 but far exceeding those of CA-4. Compounds 1 (butanoyl side chain) and 2-3 inhibit tubulin polymerization in vitro in a manner similar to that of CA-4 and AmCA-4 whereas compounds 4, 5 (octanoyl side chain) and 6 (dodecanoyl side chain) may be considered as partial inhibitors of tubulin polymerization. While all derivatives are able to accumulate cells in G2/M phase, compounds with the longest acyl chains (5 and 6) are the least active ones in this particular action. Moreover, compounds 2-3 were the most active ones as c-Myc downregulators. CONCLUSION: Our studies show that the most active compounds in the disruption of the microtubule network are also the most potent ones in the downregulation of c-Myc expression. Other: Compounds 2 and 3 are good candidates for in vivo studies as they combine the best antimitotic and c-Myc downregulation activities at low doses.

N-alpha-Aminoacyl Colchicines as Promising Anticancer Agents.

BACKGROUND: In the last years, many efforts have been made to find colchicine derivatives with reduced toxicity. Additionally, the deregulation of amino acid uptake by cancer cells provides an opportunity to improve anticancer drug effectiveness. OBJECTIVE: To design new colchicine derivatives with reduced cytotoxicity and enhanced selectivity by means of introducing aminoacyl groups. METHODS: 34 colchicine analogues bearing L- and D-amino acid pendants were synthetized and characterized by NMR, IR and MS techniques. Cytotoxicity and antimitotic properties were assessed by spectrophotometry and cell cycle assays. Oncogene downregulation was studied by RTqPCR whereas in vivo studies were performed in SCID mice. RESULTS: Compounds exhibit high antiproliferative activities at the nanomolar level while being, in general, less cytotoxic than colchicine. Most compounds inhibit the polymerization of tubulin in a way similar to colchicine itself, with L-amino acid derivatives being the most active in the inhibition of tubulin polymerization. All selected compounds caused cell cycle arrest at the G2/M phase when tested at 1 µM. More specifically, Boc-L-proline derivative 6 arrested half of the population and showed one of the highest Selectivity Indexes. Derivatives 1 (Boc-glycine), 27 (D-leucine) and 31 (Boc-glycine-glycine) proved fairly active in downregulating the expression of the c-Myc, hTERT and VEGF oncogenes, with compound 6 (Boc-L-proline) having the highest activity. This compound was shown to exert a potent anti-tumor effect when administered intraperitoneally (LD50 > 100 mg/kg for 6, compared with 2.5 mg/kg for colchicine). CONCLUSION: Compound 6 offers an opportunity to be used in cancer therapy with less toxicity problems than colchicine.

Synthesis of Combretastatin A-4 and 3'-Aminocombretastatin A-4 derivatives with Aminoacid Containing Pendants and Study of Their Interaction with Tubulin and as Downregulators of the VEGF, hTERT and c-Myc Gene Expression.

Natural product combretastatin A-4 (CA-4) and its nitrogenated analogue 3'-aminocombretastatin A-4 (AmCA-4) have shown promising antitumor activities. In this study, a range of CA-4 and AmCA-4 derivatives containing amino acid pendants have been synthesized in order to compare their biological actions with those of their parent compounds. Thus, inhibition of cell proliferation on tumor cell lines HT-29, MCF-7 and A-549, as well as on the nontumor cell line HEK-273; in vitro tubulin polymerization; mitotic cell arrest; action on the microtubule cell network and inhibition of VEGF, hTERT, and c-Myc genes have been evaluated. Some AmCA-4 derivatives bearing L-amino acids exhibited inhibition of cell proliferation at low nanomolar levels exceeding the values shown by AmCA-4. Furthermore, while CA-4 and AmCA-4 derivatives do not show significant effects on the in vitro tubulin polymerization and cell cycle arrest, some selected CA-4 and AmCA-4 derivatives are able to cause total depolymerization of the microtubule network on A-549 cells. The best results were obtained in the inhibition of gene expression, particularly on the VEGF gene, in which some AmCA-4 derivatives greatly exceeded the inhibition values achieved by the parent compound.

Novel multitarget inhibitors with antiangiogenic and immunomodulator properties.

By means of docking studies, seventeen compounds T.1-T17 have been designed and evaluated as multitarget inhibitors of VEGFR-2 and PD-L1 proteins in order to overcome resistance phenomena offered by cancer. All these designed molecules display a urea moiety as a common structural feature and eight of them (T.1-T8) further contain a 1,2,3-triazol moiety. The antiproliferative activity of these molecules on several tumor cell lines (HT-29, MCF-7, HeLa, A549, HL-60), on the endothelial cell line HMEC-1 and on the non-tumor cell line HEK-293 has been determined. The urea derivatives were also evaluated for their antiangiogenic properties, whereby their ability to inhibit tubulogenesis and kinase activity employing flow cytometry, ELISA, immunofluorescence and western blot techniques was measured. In addition, these techniques were also employed to investigate the immunomodulator action of the synthetic compounds on the inhibition of PD-L1 and c-Myc proteins. Compound T.2, 1-(3-chlorophenyl)-3-(2-(4-(4-methoxybenzyl)-1H-1,2,3-triazol-1-yl)ethyl)urea, has shown similar results to sorafenib in both down-regulation of VEGFR-2 and inhibition of the kinase activity of this receptor. Furthermore, compound T.14, (E)-1-(4-chlorophenyl)-3-(3-(4-methoxystyryl)phenyl)urea, improves the effect of T.2 as regards tube formation of endothelial cells and inhibition of VEGFR-2 tyrosine kinase activity. In addition, T.14 improves the effect of the experimental drug BMS-8 in the inhibition of PD-L1 and c-Myc proteins.

Arylpyridines, arylpyrimidines and related compounds as potential modulator agents of the VEGF, hTERT and c-Myc oncogenes.

Twenty-four derivatives structurally related to honokiol have been synthesized and biologically evaluated. IC50 values were determined towards the HT-29, MCF-7 and HEK-293 cell lines. Some of these derivatives exhibited comparable or lower IC50 values than honokiol towards the HT-29 and MCF-7 cell lines or else higher selectivity indexes than the natural product. Twelve selected derivatives were evaluated for their ability to inhibit the expression of the VEGFA, hTERT and c-Myc genes and also to inhibit the production of total c-Myc protein and the secretion of the VEGF protein. One of the most promising compounds, 3-(2,4-dimethoxyphenyl)pyridine, may be a good candidate for further studies as an anticancer agent as it is able to improve the effect shown by honokiol in downregulating all gene expression and protein production at a safe concentration for non-tumor cells.

Synthesis and biological evaluation as antiangiogenic agents of ureas derived from 3'-aminocombretastatin A-4.

Twenty-six compounds derived from 3'-aminocombretastatin A-4 (AmCA-4) containing a urea fragment mimicking the structure of Sorafenib, have been synthesized and evaluated as antiangiogenic compounds. Antiproliferative activity of all the synthetic ureas has been measured on tumor cell lines HT-29, MCF-7, HeLa, A-549 and HL-60 as well as on the endothelial cell line HMEC-1 and on the non-tumor cell line HEK-293. Preliminary docking studies were developed in order to predict which ureas show better interactions with the protein VEGFR-2. Then, the selected derivatives were evaluated in terms of their apoptotic effect and antiangiogenic properties. In this regard, VEGFR-2/ligand interactions were determined by flow cytometry and immunofluorescence techniques. Inhibition of VEGFR-2 tyrosine kinase activity in both the A-549 and HMEC-1 cell lines was also carried out. In addition, tube formation inhibition was studied in endothelial cells. Ortho-chloro substituted urea 5 and ortho-bromo substituted urea 8 were the most active ones in both down-regulation of VEGFR-2 and inhibition of the kinase activity of this receptor, with better results than those obtained with sunitinib and sorafenib.

[Prostate carcinosarcoma.] / Carcinosarcoma de próstata.

OBJECTIVE: To report a new case of prostatic carcinosarcoma, an uncommon and locally and distance aggressive tumor. METHOD: We analyzed one case diagnosed in our Center, from clinical and pathological diagnosis to death, describing the treatments received. RESULT: Patient presented a huge pelvic mass and a pulmonary metastasis that was treated with cystoprostatectomy and bilateral cutaneous ureterostomy with the diagnosis of carcinosarcoma of the prostate. He received 8 cycles of Docetaxel with bone progression and then 3 cycles of doxorubicin, suspending treatment due to progression. The survival was 18 months. CONCLUSIONS: Prostate carcinosarcoma is a very aggressive neoplasia that does not respond to the usual treatments of prostate cancer.

Carcinosarcoma de próstata / Prostate carcinosarcoma

OBJETIVO: Reportar un nuevo caso de carcinosarcoma prostático, un tumor infrecuente y agresivo localmente y a distancia. MÉTODO: Se ha analizado un único caso diagnosticado en nuestro Centro, desde el diagnóstico clínico y anatomopatológico hasta el éxitus, describiéndose los tratamientos recibidos por el mismo. RESULTADO: Paciente que presenta gran masa pélvica y una metástasis pulmonar que es sometido a cistoprostatectomia y ureterostomía cutánea bilateral con el diagnóstico de carcinosarcoma de próstata. Recibió 8 ciclos de Docetaxel objetivándose progresión ósea y posteriormente 3 ciclos de Doxorrubicina suspendiéndose por progresión. La supervivencia fue de 18 meses. CONCLUSIONES: El carcinosarcoma prostático es una neoplasia muy agresiva que no responde a los tratamientos habituales del cáncer de próstata

OBJECTIVE: To report a new case of prostatic carcinosarcoma, an uncommon and locally and distance aggressive tumor. METHOD: We analyzed one case diagnosed in our Center, from clinical and pathological diagnosis to death, describing the treatments received. RESULT: Patient presented a huge pelvic mass and a pulmonary metastasis that was treated with cystoprostatectomy and bilateral cutaneous ureterostomy with the diagnosis of carcinosarcoma of the prostate. He received 8 cycles of Docetaxel with bone progression and then 3 cycles of doxorubicin, suspending treatment due to progression. The survival was 18 months. CONCLUSIONS: Prostate carcinosarcoma is a very aggressive neoplasia that does not respond to the usual treatments of prostate cancer

Synthesis and biological evaluation of cyclic derivatives of combretastatin A-4 containing group 14 elements.

Several tricyclic compounds inspired by the structure of combretastatin A-4 and bearing group 14 elements have been synthesized by homocoupling lithiated aryl fragments followed by ring-closing metathesis. These tricyclic compounds and their diolefin precursors were evaluated for their antiproliferative action on the tumor cell lines HT-29, MCF-7, HeLa and A-549 and on the non-tumor cell line HEK-293. In addition, their effects on the cell cycle were also measured. The tricyclic compounds show antiproliferative activity similar to that of combretastatin A-4, even though they are not so active in arresting the cell cycle. However, some diolefin precursors are able to cause accumulation of cells in the G2/M phase in a higher percentage than combretastatin A-4 itself. Inhibition of endothelial tube formation and VEGFR-2 phosphorylation of some selected compounds is comparable to that of combretastatin A-4, particularly those of tin-containing compounds 23c and 26c, whose actions exceed those of sorafenib, a clinically used VEGFR-2 inhibitor.

Arylureas derived from colchicine: Enhancement of colchicine oncogene downregulation activity.

Our efforts to get therapeutically useful colchicine derivatives for the treatment of cancer have led us to synthetize and biologically evaluate twenty-seven N,N'-disubstituted ureas containing a colchicine moiety and an aryl fragment. The cytotoxicity of the compounds, their ability to inhibit the expression of oncogenes related to telomerase activation and to the VEGF/VEGFR-2 autocrine process, such as c-MYC, hTERT and VEGF and their capability to downregulate c-MYC and VEGFR-2 proteins and the secretion of VEGF have been measured. In these biological evaluations, we have found that the change of the acetyl group in colchicines for an N-arylurea unit causes a great improvement in anticancer properties. The most promising derivatives were compounds 6 (o-Cl) and 14 (o,o-di-F) as they were able to downregulate all the tested targets at a concentration below their IC50 values. Thus, the arylurea unit enhances the potential of colchicine as an anticancer agent.

Effects on tubulin polymerization and down-regulation of c-Myc, hTERT and VEGF genes by colchicine haloacetyl and haloaroyl derivatives.

Several colchicine analogues in which the N-acetyl residue has been replaced by haloacetyl, cyclohexylacetyl, phenylacetyl and various aroyl moieties have been synthesized. The cytotoxic activities of the synthesized compounds have been measured on three tumor cell lines (HT-29, MCF-7 and A549) and on one non-tumor cell line (HEK-293). These compounds exhibit high antiproliferative activities at the nanomolar level, in many cases with a higher potency than colchicine itself. Some of the compounds, particularly the haloacetyl derivatives, inhibit the polymerization of tubulin in a similar manner as colchicine. As regards the cell cycle, the most active compounds are the chlorobenzoyl and bromobenzoyl derivatives, which cause cell cycle arrest at the G2/M phase when tested at 20 nM, and the bromoacetyl derivative, which arrests the cell cycle at 15 nM. In addition, these colchicine derivatives have shown fairly active downregulating the expression of the c-Myc, hTERT and VEGF genes, as well as VEGF protein secretion, at very low concentrations.

Synthesis and biological evaluation of carbamates derived from aminocombretastatin A-4 as vascular disrupting agents.

A series of twenty-six carbamates derived from aminocombretastatin A-4 (AmCA-4) were synthesized and evaluated for their capacity to affect cell proliferation, tubulin polymerization, mitotic cell arrest, microtubule network organization, apoptosis and endothelial tubular structures in vitro. The anti-proliferative activity of the synthetic carbamates was measured on several human tumor cell lines (i.e. HT-29, MCF-7, HeLa, A-549, MDA-MB-231, HL-60) as well as on the endothelial cell line HMEC-1 and the non-tumor cell line HEK-293. The compounds showed anti-proliferative activity in the nanomolar range thereby exceeding by far the activity of combretastatin A-4 (CA-4) and, in some cases, the activity of AmCA-4. The most active compounds proved to be the carbamates bearing chloro, bromo or methoxy groups in the meta position of the phenyl ring. Moreover, all carbamates inhibited in vitro tubulin polymerization, in a similar manner to that of CA-4 and AmCA-4 by interacting with the colchicine binding site in tubulin. The synthetic carbamates proved as active as AmCA-4 in causing mitotic arrest, as assessed in A549 human lung cancer cells, and disruption of the microtubule cellular network. Some selected carbamates induced apoptosis at concentrations as low as 10 nM, being more active than AmCA-4. Finally, these selected carbamates displayed a vascular disrupting activity on endothelial cells in a dose-dependent manner. In conclusion, our data indicate that carbamates derived from aminocombretastatin A-4 represent interesting lead compounds for the design of vascular disrupting agents.

Synthesis and Biological Evaluation of Imines Structurally Related to Resveratrol as Dual Inhibitors of VEGF Protein Secretion and hTERT Gene Expression.

A group of 28 N-benzylidene aniline derivatives structurally related to the natural stilbene resveratrol has been prepared through condensation of anilines with the corresponding aldehydes. The ability of these imines to inhibit proliferation of two tumor cell lines (HT-29 and MCF-7) and one non-tumor cell line (HEK- 293) was first determined. Subsequently, we determined the ability of some of the most cytotoxic compounds to inhibit the secretion of the VEGF-A factor in HT-29 cells and to downregulate the expression of the VEGF and hTERT genes, the latter one being involved in the activation of telomerase.

Synthesis of honokiol analogues and evaluation of their modulating action on VEGF protein secretion and telomerase-related gene expressions.

A group of 36 biphenyl derivatives structurally related to honokiol were synthesized by means of Suzuki coupling reactions. Their cytotoxicities were evaluated and compared to that of honokiol. Some of the compounds were then evaluated for their ability to downregulate the secretion of the VEGF protein and the expression of the VEGF, hTERT, and c-Myc genes; the two latter involved in the activation of telomerase in tumoral cells. Some of the synthetized derivatives showed promising pharmacological features as they exhibited IC50 values in low micromolar range, good therapeutic margins, and a multiple mode of action on tumor cells based on the inhibition of VEGF and, at the same time, of the expression of genes related to the activation of telomerase.

Interactions of long-chain homologues of colchicine with tubulin.

Several colchicine analogues in which the N-acetyl residue has been replaced by aliphatic, straight-chain acyl moieties, have been synthesized. These compounds show high cytotoxic activity at the nanomolar level against the tumoral cell lines HT-29, MCF-7 and A549. Some of them exhibit activities in the picomolar range against the HT-29 line and are thus two to three orders of magnitude more cytotoxic than colchicine. In this specific cell line, the activities were found to be closely related to the length of the acyl carbon chain, an increase in the latter giving rise to an increase in the cytotoxicity with a maximum in the range of 10-12 carbon atoms, followed by a decrease in activity with still longer chains. Some of the compounds inhibit microtubule assembly and induce the formation of abnormal polymers and present in most cases better apparent affinity constants than colchicine. In addition, at IC50 concentrations the analogues block the cell cycle of A549 cells in the G2/M phase. Molecular docking studies suggest that, while interactions of the colchicine analogues with the colchicine binding site at ß-tubulin are still present, the increase in the acyl chain length leads to the progressive development of new interactions, not present in colchicine itself, with the neighboring α-tubulin subunit. Indeed, sufficiently long acyl chains span the intradimer interface and contact with a hydrophobic groove in α-tubulin. It is worth noting that some of the compounds show cytotoxicity at concentrations three orders of magnitude lower than colchicine. Their pharmacological use in cancer therapy could possibly be performed with lower dosages and be thus endowed with less acute toxicity problems than in the case of colchicine.

Synthesis and biological evaluation of simplified pironetin analogues with modifications in the side chain and the lactone ring.

The preparation of several new analogues of the natural dihydropyrone pironetin is described. They differ from the natural product mainly in the nature of the side chain and the lactone ring. Their cytotoxic activity has been measured. In addition, their interaction with tubulin, their ability to inhibit the secretion of the vascular endothelial growth factor (VEGF) and the expression of angiogenesis and telomerase-related genes have been determined. Unexpectedly, and unlike pironetin, the lactones studied in this work do not interact with tubulin. Two of the compounds have been found to downregulate the expression of the hTERT and VEGF genes. Furthermore, one of them causes an appreciably decrease in the secretion of the VEGF protein.

Pironetin Binds Covalently to αCys316 and Perturbs a Major Loop and Helix of α-Tubulin to Inhibit Microtubule Formation.

Microtubule-targeting agents are among the most powerful drugs used in chemotherapy to treat cancer patients. Pironetin is a natural product that displays promising anticancer properties by binding to and potently inhibiting tubulin assembly into microtubules; however, its molecular mechanism of action remained obscure. Here, we solved the crystal structure of the tubulin-pironetin complex and found that the compound covalently binds to Cys316 of α-tubulin. The structure further revealed that pironetin perturbs the T7 loop and helix H8 of α-tubulin. Since both these elements are essential for establishing longitudinal tubulin contacts in microtubules, this result explains how pironetin inhibits the formation of microtubules. Together, our data define the molecular details of the pironetin binding site on α-tubulin and thus offer a promising basis for the rational design of pironetin variants with improved activity profiles. They further extend our knowledge on strategies evolved by natural products to target and perturb the microtubule cytoskeleton.

Synthesis and evaluation of biphenyl derivatives as potential downregulators of VEGF protein secretion and telomerase-related gene expressions.

A group of 47 biphenyl functionalized compounds, prepared by means of Suzuki couplings, has been investigated for their cytotoxicity on two tumoral cell lines (HT-29 and MCF-7) and one non tumoral cell line (HEK-293). 29 selected compounds have been investigated for their ability to inhibit the production of the vascular endothelial growth factor (VEGF). Subsequently, the capacity of the compounds to downregulate the expression of the VEGF, h-TERT and c-Myc genes, the two latter involved in the control of the activation of telomerase, has also been determined.

[Emphysematous cystitis: Report of 2 cases with different outcomes]. / CYSTITIS ENFISEMATOSA: 2 CASOS CON DIFERENTE EVOLUCIÓN.

OBJECTIVE: To report two cases of emphysematous cystitis, a rare, potentially serious disease. METHODS: Analysis of two different cases treated in our center and review of the existing literature. RESULTS: One patient underwent emergency surgery (radical cystectomy) due to the advanced stage of the disease. The second patient, whose was in an initial stage, benefited from a new treatment, consisting of hyperbaric oxygen and wide spectrum antibiotics. CONCLUSIONS: Early diagnosis is the cornerstone of the conservative management of the disease. Hyperbaric oxygen therapy may be beneficial due to the improvement in oxygenation of the tissues affected by the disease.

Inhibitory effect of cytotoxic stilbenes related to resveratrol on the expression of the VEGF, hTERT and c-Myc genes.

A group of thirty-nine stilbene derivatives, prepared by means of Heck coupling reactions, has been investigated for their cytotoxicity, as well as for their ability to inhibit the production of the vascular endothelial growth factor (VEGF) and the activation of telomerase. The ability of these compounds to inhibit proliferation of two tumoral cell lines (HT-29 and MCF-7) and one non tumoral cell line (HEK-293) was first determined. Subsequently, we determined the capacity of the compounds to inhibit the secretion of VEGF in the aforementioned cell lines and to downregulate the expression of the VEGF, hTERT and c-Myc genes, the two latter involved in the control of the activation of telomerase. One of the synthetic stilbenes, (E)-4-(4-methoxystyryl)aniline, showed strong cytotoxicity and proved able to cause a marked decrease both in the secretion of VEGF and in the expression of the hTERT and c-Myc genes, in all cases at concentrations in the low nanomolar range.