Key role of PIN1 in telomere maintenance and oncogenic behavior in a human glioblastoma model.

PIN1 is the only known enzyme capable of recognizing and isomerizing the phosphorylated Serine/Threonine­Proline motif. Through this mechanism, PIN1 controls diverse cellular functions, including telomere maintenance. Both PIN1 overexpression and its involvement in oncogenic pathways are involved in several cancer types, including glioblastoma (GBM), a lethal disease with poor therapeutic resources. However, knowledge of the role of PIN1 in GBM is limited. Thus, the present work aimed to study the role of PIN1 as a telomere/telomerase regulator and its contribution to tumor biology. PIN1 knockout (KO) LN­229 cell variant using CRISPR/Cas9 was developed and compared with PIN1 LN­229 expressing cells. To study the effect of PIN1 absence, status of NF­κB pathway was evaluated by luciferase reporter gene assay and quantitative PCR. Results revealed that PIN1 deletion in GBM cells diminished the active levels of NF­κB and decrease the transcription of il­8 and htert genes. Then, telomere/telomerase related processes were studied by RQ­TRAP assay and telomere length determination by qPCR, obtaining a reduction both in telomerase activity as in telomere length in PIN1 KO cells. In addition, measurement of SA ß­galactosidase and caspase­3 activities revealed that loss of PIN1 triggers senescence and apoptosis. Finally, migration, cell cycle progression and tumorigenicity were studied by flow cytometry/western blot, Transwell assay and in vivo experiments, respectively. PIN1 deletion decreased migration as well as cell cycle progression by increasing doubling time and also resulted in the loss of LN­229 cell ability to form tumors in mice. These results highlight the role of PIN1 in telomere homeostasis and GBM progression, which supports PIN1 as a potential molecular target for the development of novel therapeutic agents for GBM treatment.

Preclinical Efficacy and Toxicology Evaluation of RAC1 Inhibitor 1A-116 in Human Glioblastoma Models.

Malignant gliomas are the most common primary central nervous system tumor in adults. Despite current therapeutics, these tumors are associated with poor prognosis and a median survival of 16 to 19 months. This highlights the need for innovative treatments for this incurable disease. Rac1 has long been associated with tumor progression and plays a key role in glioma's infiltrative and invasive nature. The aim of this study is to evaluate the 1A-116 molecule, a Rac1 inhibitor, as targeted therapy for this aggressive disease. We found that targeting Rac1 inhibits cell proliferation and cell cycle progression using different in vitro human glioblastoma models. Additionally, we evaluated 1A-116 in vivo, showing a favorable toxicological profile. Using in silico tools, 1A-116 is also predicted to penetrate the blood-brain barrier and present a favorable metabolic fate. In line with these results, 1A-116 i.p daily treatment resulted in a dose-dependent antitumor effect in an orthotopic IDH-wt glioma model. Altogether, our study provides a strong potential for clinical translation of 1A-116 as a signal transduction-based precision therapy for glioma and also increases the evidence of Rac1 as a key molecular target.

Rational design of PIN1 inhibitors for cancer treatment based on conformational diversity analysis and docking based virtual screening.

The parvulin PIN1 (peptidyl-prolyl cis-trans isomerase NIMA-interacting 1), is the only enzyme capable of isomerizing prolines of phospho-Serine/Threonine-Proline motifs. PIN1 binds to a subset of proteins and plays an essential role in regulating protein function post-phosphorylation control. Furthermore, the activity of PIN1 regulates the outcome of the signalling of proline-directed kinases (e.g. MAPK, CDK, or GSK3) and thus regulates cell proliferation and cell survival. For these reasons, PIN1 inhibitors are interesting since they may have therapeutic implications for cancer. Several authors have already reported that the non-structural point mutation Trp34Ala prevents PIN1 from interacting with its downstream effector proteins. In this work, we characterized PIN1 structurally, intending to explore new inhibition targets for the rational design of pharmacological activity compounds. Through a conformational diversity analysis of PIN1, we identified and characterized a highly specific druggable pocket around the residue Trp34. This pocket was used in a high-throughput docking screening of 450,000 drug-like compounds, and the top 10 were selected for re-docking studies on the previously used conformers. Finally, we evaluated the binding of each compound by thermal shift assay and found four molecules with a high affinity for PIN1 and potential inhibitory activity. Through this strategy, we achieved novel drug candidates with the ability to interfere with the phosphorylation-dependent actions of PIN1 and with potential applications in the treatment of cancer.Communicated by Ramaswamy H. Sarma.

New inhibitor targeting Acyl-CoA synthetase 4 reduces breast and prostate tumor growth, therapeutic resistance and steroidogenesis.

Acyl-CoA synthetase 4 (ACSL4) is an isoenzyme of the fatty acid ligase-coenzyme-A family taking part in arachidonic acid metabolism and steroidogenesis. ACSL4 is involved in the development of tumor aggressiveness in breast and prostate tumors through the regulation of various signal transduction pathways. Here, a bioinformatics analysis shows that the ACSL4 gene expression and proteomic signatures obtained using a cell model was also observed in tumor samples from breast and cancer patients. A well-validated ACSL4 inhibitor, however, has not been reported hindering the full exploration of this promising target and its therapeutic application on cancer and steroidogenesis inhibition. In this study, ACSL4 inhibitor PRGL493 was identified using a homology model for ACSL4 and docking based virtual screening. PRGL493 was then chemically characterized through nuclear magnetic resonance and mass spectroscopy. The inhibitory activity was demonstrated through the inhibition of arachidonic acid transformation into arachidonoyl-CoA using the recombinant enzyme and cellular models. The compound blocked cell proliferation and tumor growth in both breast and prostate cellular and animal models and sensitized tumor cells to chemotherapeutic and hormonal treatment. Moreover, PGRL493 inhibited de novo steroid synthesis in testis and adrenal cells, in a mouse model and in prostate tumor cells. This work provides proof of concept for the potential application of PGRL493 in clinical practice. Also, these findings may prove key to therapies aiming at the control of tumor growth and drug resistance in tumors which express ACSL4 and depend on steroid synthesis.

Computational and in vitro Pharmacodynamics Characterization of 1A-116 Rac1 Inhibitor: Relevance of Trp56 in Its Biological Activity.

In the last years, the development of new drugs in oncology has evolved notably. In particular, drug development has shifted from empirical screening of active cytotoxic compounds to molecularly targeted drugs blocking specific biologic pathways that drive cancer progression and metastasis. Using a rational design approach, our group has developed 1A-116 as a promising Rac1 inhibitor, with antitumoral and antimetastatic effects in several types of cancer. Rac1 is over activated in a wide range of tumor types and and it is one of the most studied proteins of the Rho GTPase family. Its role in actin cytoskeleton reorganization has effects on endocytosis, vesicular trafficking, cell cycle progression and cellular migration. In this context, the regulatory activity of Rac1 affects several key processes in the course of the cancer including invasion and metastasis. The purpose of this preclinical study was to focus on the mode of action of 1A-116, conducting an interdisciplinary approach with in silico bioinformatics tools and in vitro assays. Here, we demonstrate that the tryptophan 56 residue is necessary for the inhibitory effects of 1A-116 since this compound interferes with protein-protein interactions (PPI) of Rac1GTPase involving several GEF activators. 1A-116 is also able to inhibit the oncogenic Rac1P29S mutant protein, one of the oncogenic drivers found in sun-exposed melanoma. It also inhibits numerous Rac1-regulated cellular processes such as membrane ruffling and lamellipodia formation. These results deepen our knowledge of 1A-116 inhibition of Rac1 and its biological impact on cancer progression. They also represent a good example of how in silico analyses represent a valuable approach for drug development.

Telomeropathies: Etiology, diagnosis, treatment and follow-up. Ethical and legal considerations.

Telomeropathies involve a wide variety of infrequent genetic diseases caused by mutations in the telomerase maintenance mechanism or the DNA damage response (DDR) system. They are considered a family of rare diseases that often share causes, molecular mechanisms and symptoms. Generally, these diseases are not diagnosed until the symptoms are advanced, diminishing the survival time of patients. Although several related syndromes may still be unrecognized this work describes those that are known, highlighting that because they are rare diseases, physicians should be trained in their early diagnosis. The etiology and diagnosis are discussed for each telomeropathy and the treatments when available, along with a new classification of this group of diseases. Ethical and legal issues related to this group of diseases are also considered.

Preclinical Efficacy of [V4 Q5 ]dDAVP, a Second Generation Vasopressin Analog, on Metastatic Spread and Tumor-Associated Angiogenesis in Colorectal Cancer.

PURPOSE: Control of metastatic spread of colorectal cancer (CRC) remains as a major therapeutic challenge. [V4 Q5 ]dDAVP is a vasopressin peptide analog with previously reported anticancer activity against carcinoma tumors. By acting as a selective agonist of arginine vasopressin type 2 membrane receptor (AVPR2) present in endothelial and tumor cells, [V4Q5]dDAVP is able to impair tumor aggressiveness and distant spread. Our aim was to evaluate the potential therapeutic benefits of [V4Q5]dDAVP on highly aggressive CRC disease using experimental models with translational relevance. MATERIALS AND METHODS: Murine CT-26 and human Colo-205 AVPR2-expressing CRC cell lines were used to test the preclinical efficacy of [V4Q5]dDAVP, both in vitro and in vivo. RESULTS: In syngeneic mice surgically implanted with CT-26 cells in the spleen, sustained intravenous treatment with [V4Q5]dDAVP (0.3 µg/kg) dramatically impaired metastatic progression to liver without overt signs of toxicity, and also reduced experimental lung colonization. The compound inhibited in vivo angiogenesis driven by Colo-205 cells in athymic mice, as well as in vitro endothelial cell migration and capillary tube formation. [V4Q5]dDAVP exerted AVPR2-dependent cytostatic activity in vitro (IC50 1.08 µM) and addition to 5-fluorouracil resulted in synergistic antiproliferative effects both in CT-26 and Colo-205 cells. CONCLUSION: The present preclinical study establishes for the first time the efficacy of [V4Q5]dDAVP on CRC. These encouraging. RESULTS: suggest that the novel second generation vasopressin analog could be used for the management of aggressive CRC as an adjuvant agent during surgery or to complement standard chemotherapy, limiting tumor angiogenesis and metastasis and thus protecting the patient from CRC recurrence.

[Rho GTPases as molecular targets in cancer. Strategies and therapeutic opportunities]. / Rho GTPasas como blancos moleculares en cáncer. Estrategias y oportunidades terapéuticas.

Rho GTPases are molecular switches that control the different cellular processes. Deregulation of these proteins is associated to transformation and malignant progression in several cancer types. Given the evidence available of the role of Rho GTPases in cancer it is suggested that these proteins can serve as potential therapeutic targets. This review focuses on the strategies used to develop Rho GTPases modulators and their potential use in therapeutic settings.

RHO GTPasas como blancos moleculares en cáncer: Estrategias y oportunidades terapéuticas / Rho GTPases as molecular targets in cancer. Strategies and therapeutic opportunities

Las Rho GTPasas son una familia de proteínas que actúan como interruptores moleculares en diversas vías de señalización coordinando la regulación de distintos procesos celulares. La desregulación de dichas proteínas se vincula con transformación maligna y progresión tumoral en distintos tipos de cáncer. Por estos motivos, en los últimos años las Rho GTPasas fueron postuladas como blancos moleculares interesantes. En este trabajo describimos las distintas estrategias estudiadas utilizando a las Rho GTPasas como blanco y su grado de avance, mostrando una estrategia novedosa para el tratamiento del cáncer.

Rho GTPases are molecular switches that control the different cellular processes. Deregulation of these proteins is associated to transformation and malignant progression in several cancer types. Given the evidence available of the role of Rho GTPases in cancer it is suggested that these proteins can serve as potential therapeutic targets. This review focuses on the strategies used to develop Rho GTPases modulators and their potential use in therapeutic settings.

AZT exerts its antitumoral effect by telomeric and non-telomeric effects in a mammary adenocarcinoma model.

Limitless replicative potential is one of the hallmarks of cancer that is mainly due to the activity of telomerase. This holoenzyme maintains telomere length, adding TTAGGG repetitions at the end of chromosomes in each cell division. In addition to this function, there are extratelomeric roles of telomerase that are involved in cancer promoting events. It has been demonstrated that TERT, the catalytic component of telomerase, acts as a transcriptional modulator in many signaling pathways. Taking into account this evidence and our experience on the study of azidothymidine (AZT) as an inhibitor of telomerase activity, the present study analyzes the effect of AZT on some telomeric and extratelomeric activities. To carry out the present study, we evaluated the transcription of genes that are modulated by the Wnt/ß-catenin pathway, such as c-Myc and cyclin-D1 (Cyc-D1) and cell processes related with their expression, such as, proliferation, modifications of the actin cytoskeleton, cell migration and cell cycle in a mammary carcinoma cell line (F3II). Results obtained after treatment with AZT (600 µM) for 15 passages confirmed the inhibitory effect on telomerase. Regarding extratelomeric activities, our results showed a decrease of 64, 38 and 25% in the transcription of c-Myc, Cyc-D1 and TERT, respectively (p<0.05) after AZT treatment. Furthermore, we found an effect on cell migration, reaching an inhibition of 48% (p<0.05) and a significant passage-dependent increase on cell doubling time during treatment. Finally, we evaluated the effect on cell cycle, obtaining a decline in G0/G1 in AZT-treated cells. These results allow us to postulate that AZT is not only an inhibitor of telomerase activity, but also a potential modulator of extratelomeric processes involved in cancer promotion.

Addition of vasopressin synthetic analogue [V(4)Q(5)]dDAVP to standard chemotherapy enhances tumour growth inhibition and impairs metastatic spread in aggressive breast tumour models.

[V(4)Q(5)]dDAVP is a novel 2nd generation vasopressin analogue with robust antitumour activity against metastatic breast cancer. We recently reported that, by acting on vasopressin V2r membrane receptor present in tumour cells and microvascular endothelium, [V(4)Q(5)]dDAVP inhibits angiogenesis and metastatic progression of the disease without overt toxicity. Despite chemotherapy remaining as a primary therapeutic option for aggressive breast cancer, its use is limited by low selectivity and associated adverse effects. In this regard, we evaluated potential combinational benefits by adding [V(4)Q(5)]dDAVP to standard-of-care chemotherapy. In vitro, combination of [V(4)Q(5)]dDAVP with sub-IC50 concentrations of paclitaxel or carmustine resulted in a cooperative inhibition of breast cancer cell growth in comparison to single-agent therapy. In vivo antitumour efficacy of [V(4)Q(5)]dDAVP addition to chemotherapy was first evaluated using the triple-negative MDA-MB-231 breast cancer xenograft model. Tumour-bearing mice were treated with i.v. injections of [V(4)Q(5)]dDAVP (0.3 µg/kg, thrice weekly) in combination with weekly cycles of paclitaxel (10 mg/kg i.p.). After 6 weeks of treatment, combination regimen resulted in greater tumour growth inhibition compared to monotherapy. [V(4)Q(5)]dDAVP addition was also associated with reduction of local aggressiveness, and impairment of tumour invasion and infiltration of the skin. Benefits of combined therapy were confirmed in the hormone-independent and metastatic F3II breast cancer model by combining [V(4)Q(5)]dDAVP with carmustine (25 mg/kg i.p.). Interestingly, [V(4)Q(5)]dDAVP plus cytotoxic agents severely impaired colony forming ability of tumour cells and inhibited breast cancer metastasis to lung. The present study shows that [V(4)Q(5)]dDAVP may complement conventional chemotherapy by modulating metastatic progression and early stages of microtumour establishment, and thus supports further preclinical testing of the compound for the management of aggressive breast cancer.

A phase II dose-escalation trial of perioperative desmopressin (1-desamino-8-d-arginine vasopressin) in breast cancer patients.

Desmopressin (dDAVP) is a well-known peptide analog of the antidiuretic hormone vasopressin, used to prevent excessive bleeding during surgical procedures. dDAVP increases hemostatic mediators, such as the von Willebrand factor (vWF), recently considered a key element in resistance to metastasis. Studies in mouse models and veterinary trials in dogs with locally-advanced mammary tumors demonstrated that high doses of perioperative dDAVP inhibited lymph node and early blood-borne metastasis and significantly prolonged survival. We conducted a phase II dose-escalation trial in patients with breast cancer, administering a lyophilized formulation of dDAVP by intravenous infusion in saline, 30-60 min before and 24 h after surgical resection. Primary endpoints were safety and tolerability, as well as selection of the best dose for cancer surgery. Secondary endpoints included surgical bleeding, plasma levels of vWF, and circulating tumor cells (CTCs) as measured by quantitative PCR of cytokeratin-19 transcripts. Only 2 of a total of 20 patients experienced reversible adverse events, including hyponatremia (grade 4) and hypersensitivity reaction (grade 2). Reactions were adequately managed by slowing the infusion rate. A reduced intraoperative bleeding was noted with increasing doses of dDAVP. Treatment was associated with higher vWF plasma levels and a postoperative drop in CTC counts. At the highest dose level evaluated (2 µg/kg) dDAVP appeared safe when administered in two slow infusions of 1 µg/kg, before and after surgery. Clinical trials to establish the effectiveness of adjunctive perioperative dDAVP therapy are warranted. This trial is registered on www.clinicaltrials.gov (NCT01606072).

The novel desmopressin analogue [V4Q5]dDAVP inhibits angiogenesis, tumour growth and metastases in vasopressin type 2 receptor-expressing breast cancer models.

Desmopressin (dDAVP) is a safe haemostatic agent with previously reported antitumour activity. It acts as a selective agonist for the V2 vasopressin membrane receptor (V2r) present on tumour cells and microvasculature. The purpose of this study was to evaluate the novel peptide derivative [V4Q5]dDAVP in V2r-expressing preclinical mouse models of breast cancer. We assessed antitumour effects of [V4Q5]dDAVP using human MCF-7 and MDA-MB-231 breast carcinoma cells, as well as the highly metastatic mouse F3II cell line. Effect on in vitro cancer cell growth was evaluated by cell proliferation and clonogenic assays. Cell cycle distribution was analysed by flow cytometry. In order to study the effect of intravenously administered [V4Q5]dDAVP on tumour growth and angiogenesis, breast cancer xenografts were generated in athymic mice. F3II cells were injected into syngeneic mice to evaluate the effect of [V4Q5]dDAVP on spontaneous and experimental metastatic spread. In vitro cytostatic effects of [V4Q5]dDAVP against breast cancer cells were greater than those of dDAVP, and associated with V2r-activated signal transduction and partial cell cycle arrest. In MDA-MB-231 xenografts, [V4Q5]dDAVP (0.3 µg/kg, thrice a week) reduced tumour growth and angiogenesis. Treatment of F3II mammary tumour-bearing immunocompetent mice resulted in complete inhibition of metastatic progression. [V4Q5]dDAVP also displayed greater antimetastatic efficacy than dDAVP on experimental lung colonisation by F3II cells. The novel analogue was well tolerated in preliminary acute toxicology studies, at doses ≥ 300-fold above that required for anti-angiogenic/antimetastatic effects. Our data establish the preclinical activity of [V4Q5]dDAVP in aggressive breast cancer, providing the rationale for further clinical trials.

Proapoptotic and antiinvasive activity of Rac1 small molecule inhibitors on malignant glioma cells.

Malignant gliomas are characterized by an intrinsic ability to invade diffusely throughout the normal brain tissue. This feature contributes mainly to the failure of existing therapies. Deregulation of small GTPases signaling, in particular Rac1 activity, plays a key role in the invasive phenotype of gliomas. Here we report the effect of ZINC69391, a specific Rac1 inhibitor developed by our group, on human glioma cell lines LN229 and U-87 MG. ZINC69391 is able to interfere with the interaction of Rac1 with Dock180, a relevant Rac1 activator in glioma invasion, and to reduce Rac1-GTP levels. The kinase Pak1, a downstream effector of Dock180-Rac1 signaling, was also downregulated upon ZINC69391 treatment. ZINC69391 reduced cell proliferation, arrested cells in G1 phase, and triggered apoptosis in glioma cells. Importantly, ZINC69391 dramatically affected cell migration and invasion in vitro, interfering with actin cytoskeleton dynamics. We also evaluated the effect of analog 1A-116, a compound derived from ZINC69391 structure. 1A-116 showed an improved antiproliferative and antiinvasive activity on glioma cells. These findings encourage further preclinical testing in clinically relevant animal models.

Insight into the effect of the vasopressin analog desmopressin on lung colonization by mammary carcinoma cells in BALB/c mice.

BACKGROUND/AIM: Desmopressin (dDAVP) is a synthetic peptide analog of vasopressin with antidiuretic and hemostatic properties. Recent experimental evidence have suggested that dDAVP can inhibit metastasis formation by agonist action on V2 vasopressin receptors present in both tumor and endothelial cells. We have examined the kinetics of dDAVP effect during metastatic colonization and its potential association with hemostasis. MATERIALS AND METHODS: The experimental metastasis assay was performed by injecting F3II mammary carcinoma cells into the lateral tail vein of syngeneic female BALB/c mice. RESULTS: Clinically relevant doses of dDAVP (0.3 to 2 µg/kg intravenously (i.v.)) produced a dose-dependent inhibition in the formation of lung nodules when administered during the first 24 hours after F3II tumor cell injection. The hemostatic agent tranexamic acid (10 mg/kg, i.v.) had no effect on metastasis formation in the same experimental conditions, while the anticoagulant enoxaparin (1 mg/kg, subcutaneously (s.c.)) did not modify the antimetastatic action of dDAVP. In vitro, dDAVP had a strong inhibitory effect on F3II cell colony formation. CONCLUSION: dDAVP interferes with early metastatic disease, and direct association of this effect with hemostatic mechanisms is unlikely.

Mechanisms of cellular uptake, intracellular transportation, and degradation of CIGB-300, a Tat-conjugated peptide, in tumor cell lines.

CIGB-300 is a cyclic synthetic peptide that induces apoptosis in malignant cells, elicits antitumor activity in cancer animal models, and shows tumor reduction signs when assayed in first-in-human phase I trial in patients with cervical tumors. CIGB-300 impairs phosphorylation by casein kinase 2 through targeting the substrate's phosphoacceptor domain. CIGB-300 was linked to the cell penetrating peptide Tat to facilitate the delivery into cells. Previously, we showed that CIGB-300 had a differential antiproliferative behavior in different tumor cell lines. In this work, we studied differential antiproliferative behavior in terms of cellular uptake, intracellular transportation, and degradation in tumor cell lines with dissimilar sensitivity to CIGB-300. The internalization of CIGB-300 was studied in different malignant cell lines. We found that the cell membrane heparan sulfate proteoglycans act as main receptors for extracellular CIGB-300 uptake. The most sensitive tumor cell lines showed higher intracellular incorporation of CIGB-300 in comparison to less sensitive cell lines. Furthermore, CIGB-300 uptake is time- and concentration-dependent in all studied cell lines. It was shown that CIGB-300 has the ability to penetrate cells mainly by direct membrane translocation. However, a minor proportion of the peptide uses an energy-dependent endocytic pathway mechanism to gain access into cells. CIGB-300 is internalized and transported into cells preferentially by caveolae-mediated endocytosis. Lysosomes are involved in CIGB-300 degradation; highly sensitive cell lines showed degradation at earlier times compared to low sensitive cells. Altogether, our data suggests a mechanism of internalization, vesicular transportation, and degradation for CIGB-300 in tumor cells.