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BACKGROUND: Colorectal cancer (CRC) is ranked as the third most commonly diagnosed cancer and the third cause of cancer related deaths. CRC is greatly attributed to genetic and epigenetic mutations and immune dysregulation. Tumor aberrant expression of Toll-like Receptors (TLRs) can contribute to tumorigenesis. Recent studies suggested that microRNAs act as direct ligands of TLRs altering their expression and signaling pathways. AIM: To prove our concept that specific miRNA mimics may act as antagonists of their specific toll like receptors inhibiting their expression that could limit the release of pro-inflammatory and pro-tumorigenic cytokines leading to apoptosis of tumor cells. METHODS: From public microarray databases, we retrieved TLRs and miRNAs related to CRC followed by in silico docking of the selected miRNA ligands into the TLRs. Clinical validation after co-immunoprecipitation of TLRs and their interacting miRNA ligands was done. Expression of TLRs 1, 7,8 was determined by ELISA while miRNAs was measured by RT-qPCR. In addition, microRNA mimics of the down regulated miRNAs were transfected into human CRC cell lines. RESULTS: Our data demonstrate that TLRs 1, 7, 8 are up regulated in CRC compared to controls. Further, three miRNAs (-122, -29b and -15b) are relatively downregulated, while 4 miRNAs (-202, miRNA-98, -21 and -let7i) are upregulated in CRC patients compared to those with benign tumor and healthy controls. Transfection of down regulated miRNA mimics into CRC cell lines resulted in a significant reduction of the number and viability of cells as well as down regulating the expression of TLRs 1, 7 and 8 with ultimate reduction of downstream effector IL6 protein, suggesting that these miRNAs are negative regulators of carcinogenesis. CONCLUSION: MicroRNAs could act as antagonistic ligands of TLRs limiting the inflammatory tumor microenvironment.
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Neoplasias Colorrectales , Regulación Neoplásica de la Expresión Génica , MicroARNs , Receptor Toll-Like 8 , Microambiente Tumoral , Humanos , MicroARNs/genética , MicroARNs/metabolismo , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Neoplasias Colorrectales/metabolismo , Microambiente Tumoral/genética , Receptor Toll-Like 8/genética , Receptor Toll-Like 8/metabolismo , Línea Celular Tumoral , Receptor Toll-Like 7/genética , Receptor Toll-Like 7/metabolismo , Receptor Toll-Like 1/genética , Receptor Toll-Like 1/metabolismo , Receptores Toll-Like/metabolismo , Receptores Toll-Like/genética , Femenino , Masculino , Inflamación/genética , Inflamación/metabolismo , Transducción de SeñalRESUMEN
BACKGROUND: For effective Public Health measures, factors that influence Knowledge, Attitudes and Practices (KAP) need to be understood. In this paper, we document the relationship between levels of education on the KAP towards COVID-19 among the population of Edo State, Nigeria. METHODS: A cross-sectional KAP questionnaire was delivered across 13 communities. The study population was dichotomized into those who had or had not completed secondary education. Chi-square tests were conducted to determine statistical significance. RESULTS: Of the 538 participants, 30% had completed secondary education. Those with secondary education were significantly more likely to recognize symptoms of COVID-19 (P < 0.001). For attitudes, only one option showed a statistically significant association with 78.4% of those who did not complete secondary education having a high confidence in the church compared with 66% of those who had (P = 0.022). For practices, those who have completed secondary education practiced all of the supplied measures more than those who had not, except for taking herbal supplements. DISCUSSION: Higher levels of education impacts on knowledge and practices but has less impact on attitudes regarding how well certain individuals/organizations can handle the pandemic. Findings highlighted the importance of tailoring public health communication and strategies to local populations to improve the efficacy.
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COVID-19 , Humanos , COVID-19/epidemiología , Nigeria/epidemiología , Conocimientos, Actitudes y Práctica en Salud , Estudios Transversales , Escolaridad , Encuestas y CuestionariosRESUMEN
The anticancer agent, cisplatin (CIS), is associated with hepatotoxic effects related to activation of oxidative stress and inflammation pathways. CIS-induced oxidative DNA damage reduces sirtuin 1 (SIRT1) activity, which in turn, modulates the activity of peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α). Moreover, microRNA-34a (miRNA-34a) was shown to hinder both SIRT1 and nuclear factor erythroid 2-related factor 2 (Nrf2) activity. Thus, targeting such a pathway can alleviate CIS-induced hepatotoxicity. Betanin (BET) is a natural red glycoside food dye obtained from beets, which is reported to exhibit antioxidant function. However, its role in CIS-induced liver injury and the molecular mechanism has not been fully elucidated. Thus, the aim of this study was to investigate the ameliorative effect of BET on CIS-induced acute hepatotoxicity through the SIRT1/PGC-1α signaling pathway and illustrate the impact of miRNA-34a. Seventy-two rats were divided into six equal groups: (1) Control, (2) BET, (3) CIS, (4) CIS/BET, (5) CIS/EX527, and (6) CIS/BET/EX527. CIS-induced liver injury was evidenced by deregulated BAX and BCL2 levels, decreased levels of AMP-activated protein kinase and PGC-1α expression, and decreased SIRT1 activity. Consequently, reduced levels of Nrf2 and the expression of associated heme oxygenase-1 and glutamate-cysteine ligase modifier subunit were observed. Intriguingly, BET succeeded in reducing the CIS-induced liver injury through reducing miRNA-34a expression and enhancing the SIRT1/PGC-1α pathway. These findings coincide with the molecular docking results and the histopathological picture. In conclusion, the current research provided novel findings of the BET ameliorative effect on CIS-induced liver injury through modulating miRNA-34a expression and the SIRT1/PGC-1α signaling cascade.
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Betacianinas/farmacología , Enfermedad Hepática Inducida por Sustancias y Drogas/metabolismo , Cisplatino/efectos adversos , Hígado/metabolismo , MicroARNs/metabolismo , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Transducción de Señal/efectos de los fármacos , Sirtuina 1/metabolismo , Animales , Enfermedad Hepática Inducida por Sustancias y Drogas/tratamiento farmacológico , Enfermedad Hepática Inducida por Sustancias y Drogas/patología , Cisplatino/farmacología , Hígado/patología , Masculino , Ratas , Ratas WistarRESUMEN
Cisplatin (CIS)-mediated nephrotoxicity is induced via transforming growth factor-beta (TGF-ß) and TGF-ß-activated kinase (TAK1). TGF-ß and TAK1 are known to interact with microRNA-let-7b and microRNA-26b, respectively. Additionally, TGF-ß1 is reported to down-regulate the autophagy marker microtubule-associated protein 1 light chain 3-II (LC3-II) through upregulation of microRNA-34a. Pentoxifylline (PTX) anti-inflammatory effects are mediated via suppressing TGF-ß and regulating mammalian target of rapamycin (mTOR). The current study aimed to investigate the involvement of microRNAs let-7b, 26b, and 34a, and the modulating impact of PTX on CIS-induced nephrotoxicity. Moreover, we aimed at examining the ability of PTX to interact with TGF-ß receptor-1 (TGFßR-1), and TAK1, and examine its ability to downgrade the previously reported toxicities. Hence, the expression of the aforementioned microRNAs, and protein levels of TGFßR-1, TGF-ß1, TAK1, mTOR, LC3-II, and NF-κB were assessed. Molecular docking studies of PTX on TGFßR-1 and TAK1 were also executed. CIS induced TGF-ß1, with down-regulation of microRNA-let-7b and -26b, and up-regulation of microRNA-34a. TGFßR-1, TAK1, and mTOR levels were increased, while LC3-II level was decreased. PTX significantly protected renal cells against CIS-induced changes as indicated by reverting the level of the investigated parameters, while exhibiting an antagonistic effect on TGFßR-1 and TAK1. Our results postulate a possible role of epigenetic regulation of CIS-induced nephrotoxicity through the investigated microRNAs proposing them as potential future targets for controlling this serious toxicity. PTX was able to shield CIS-induced toxicity possibly through blocking TGF-ß pathway, while promoting autophagy in a TAK1 independent manner with the involvement of the examined microRNAs.
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Regulación de la Expresión Génica/efectos de los fármacos , Quinasas Quinasa Quinasa PAM/metabolismo , MicroARNs/metabolismo , Pentoxifilina/farmacología , Serina-Treonina Quinasas TOR/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Animales , Sitios de Unión , Cisplatino/toxicidad , Enfermedades Renales/inducido químicamente , Quinasas Quinasa Quinasa PAM/genética , Masculino , MicroARNs/genética , Modelos Moleculares , Simulación del Acoplamiento Molecular , Unión Proteica , Conformación Proteica , Distribución Aleatoria , Ratas , Serina-Treonina Quinasas TOR/genética , Factor de Crecimiento Transformador beta/genéticaRESUMEN
A new series of indolyl 1,2,4-triazole scaffolds was designed, synthesised, and biologically evaluated for their inhibitory activity against both CDK4 and CDK6. The results ranged from 0.049 µM to 3.031 µM on CDK4 and from 0.075 µM to 1.11 µM on CDK6 when compared to staurosporine, with IC50 values of 1.027 and 0.402 µM, respectively. Moreover, all compounds were tested for their cytotoxicity against two breast cancer cell lines, MCF-7 and MDA-MB-231. All of the synthesised compounds showed promising anti-proliferative activity, with two compounds Vf (IC50 = 2.91 and 1.914 µM, respectively) and Vg (IC50 = 0.891 and 3.479 µM, respectively) having potent cytotoxic activity in comparison to the reference staurosporine (IC50 = 3.144 and 4.385 µM, respectively). Vf and Vg were also found to significantly induce apoptosis to 45.33% and 37.26% (control = 1.91%) where Vf arrested the cell cycle at the S phase while Vg arrested the cycle at the G0/G1 phase. The binding mode and interactions of all compounds were studied and found to mimic those of the FDA approved CDK4/6 inhibitor palbociclib that was used as a reference throughout the study.
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Blood-brain barrier (BBB) dysfunction may be involved in the increased sensitivity of Alzheimer's disease (AD) patients to antipsychotics, including amisulpride. Studies indicate that antipsychotics interact with facilitated glucose transporters (GLUT), including GLUT1, and that GLUT1 BBB expression decreases in AD. We tested the hypotheses that amisulpride (charge: +1) interacts with GLUT1, and that BBB transport of amisulpride is compromised in AD. GLUT1 substrates, GLUT1 inhibitors and GLUT-interacting antipsychotics were identified by literature review and their physicochemical characteristics summarised. Interactions between amisulpride and GLUT1 were studied using in silico approaches and the human cerebral endothelial cell line, hCMEC/D3. Brain distribution of [3H]amisulpride was determined using in situ perfusion in wild type (WT) and 5xFamilial AD (5xFAD) mice. With transmission electron microscopy (TEM) we investigated brain capillary degeneration in WT mice, 5xFAD mice and human samples. Western blots determined BBB transporter expression in mouse and human. Literature review revealed that, although D-glucose has no charge, charged molecules can interact with GLUT1. GLUT1 substrates are smaller (184.95±6.45g/mol) than inhibitors (325.50±14.40g/mol) and GLUT-interacting antipsychotics (369.38±16.04). Molecular docking showed beta-D-glucose (free energy binding: -15.39kcal/mol) and amisulpride (-29.04kcal/mol) interact with GLUT1. Amisulpride did not affect [14C]D-glucose hCMEC/D3 accumulation. [3H]amisulpride uptake into the brain (except supernatant) of 5xFAD mice compared to WT remained unchanged. TEM revealed brain capillary degeneration in human AD. There was no difference in GLUT1 or P-glycoprotein BBB expression between WT and 5xFAD mice. In contrast, caudate P-glycoprotein, but not GLUT1, expression was decreased in human AD capillaries versus controls. This study provides new details about the BBB transport of amisulpride, evidence that amisulpride interacts with GLUT1 and that BBB transporter expression is altered in AD. This suggests that antipsychotics could potentially exacerbate the cerebral hypometabolism in AD. Further research into the mechanism of amisulpride transport by GLUT1 is important for improving antipsychotics safety.
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Enfermedad de Alzheimer , Antipsicóticos , Humanos , Ratones , Animales , Barrera Hematoencefálica/metabolismo , Amisulprida , Enfermedad de Alzheimer/metabolismo , Transportador de Glucosa de Tipo 1/metabolismo , Simulación del Acoplamiento Molecular , Encéfalo/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Antipsicóticos/farmacología , Antipsicóticos/metabolismo , Glucosa/metabolismo , Proteínas Facilitadoras del Transporte de la Glucosa/metabolismo , Subfamilia B de Transportador de Casetes de Unión a ATP/metabolismoRESUMEN
TLR4-induced mitigation of the BMP down-regulation and activin membrane bound inhibitor (BAMBI) and the consequent enhancement of the transforming growth factor-beta (TGF-ß) profibrogenic signaling has not yet been studied in cisplatin (CIS)-induced hepatotoxicity. miRNA-9 and29 have been previously reported to modulate TLR4 signaling via either tempering the expression of nuclear factor kappa-B p50 (NF-κB p50) or downregulation of extracellular matrix genes respectively. Hence we aimed to investigate the involvement of TLR4-induced modulation of TGF-ß receptor 1 (TGF-ßR1) signaling as well as the implication of miRNA-9 and 29 in CIS-induced hepatotoxicity. Moreover, we examined the ability of the phytochemical; crocin (CROC); to interact with either TLR4 or TGF-ßR1 through a molecular docking study and subsequently explore its capability to attenuate CIS-induced hepatotoxicity. CROC pretreatment ameliorated the CIS-induced enhancement of TLR4 and TGF-ß signaling and enhanced the expression of BAMBI, miRNA-9 and 29. Accordingly, it may be assumed that the protective effect of CROC against CIS-induce hepatotoxicity is mediated via the crosstalk of TLR4/NF-κBp50 signaling and BAMBI modulation of TGF-ß1 activity in addition to the up-regulation of miRNA-9 and 29. These findings came in alignment with our molecular docking results; emphasizing the molecular antagonistic activity of CROC in both TLR4 and TGF-ßR1.
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Antineoplásicos/toxicidad , Carotenoides/farmacología , Cisplatino/toxicidad , Hígado/efectos de los fármacos , Proteínas de la Membrana/metabolismo , FN-kappa B/metabolismo , Receptor Toll-Like 4/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Animales , Hígado/metabolismo , Masculino , Simulación del Acoplamiento Molecular , Ratas , Ratas Wistar , Reacción en Cadena en Tiempo Real de la Polimerasa , Transducción de Señal/efectos de los fármacosRESUMEN
Ion-pairing a lifesaving drug such as theophylline with a targeting moiety could have a significant impact on medical emergencies such as status asthmaticus or COVID-19 induced pneumomediastinum. However, to achieve rapid drug targeting in vivo the ion-pair must be protected against breakdown before the entry into the target tissue. This study aims to investigate if inserting theophylline, when ion-paired to the polyamine transporter substrate spermine, into a cyclodextrin (CD), to form a triplex, could direct the bronchodilator to the lungs selectively after intravenous administration. NMR demonstrates that upon the formation of the triplex spermine protruded from the CD cavity and this results in energy-dependent uptake in A549 cells (1.8-fold enhancement), which persists for more than 20 min. In vivo, the triplex produces a 2.4-fold and 2.2-fold increase in theophylline in the lungs 20 min after injection in rats and mice, respectively (p < 0.05). The lung targeting is selective with no increase in uptake into the brain or the heart where the side-effects of theophylline are treatment-limiting. Selectively doubling the concentration of theophylline in the lungs could improve the benefit-risk ratio of this narrow therapeutic index medicine, which continues to be important in critical care.
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BACKGROUND: Various phenolic phytochemical extracts have been claimed to exhibit different types of biological activity, including anti-inflammatory, anti-oxidative and anti-carcinogenic activity. Carnosol and carnosic acid, extracts of rosemary, are among these phenolic compounds. MATERIALS AND METHODS: CHARMm-based molecular docking was performed to estimate the possible molecular interactions of both carnosic acid and carnosol with the COX-2 active binding site. An MTT assay was used to evaluate HEp-2 cell viability after incubation for 48 hours with low or high concentrations of carnosol, carnosic acid or their combination. The levels of COX-2 were measured in cell lysate by the quantitative indirect ELISA technique. RESULTS: Docking revealed favourable negative binding energies as well as binding interactions of both carnosic acid and carnosol within the binding site of the COX-2 receptor. Carnosic acid showed more favourable binding potential than carnosol. One-way ANOVA and Bonferroni's post hoc tests revealed significant differences in cytotoxicity among cells treated with different concentrations of the rosemary extracts (P< 0.001). ELISA revealed significant reductions in COX-2 protein levels in HEp-2 cells treated with either carnosic acid (-1.42- fold) or carnosol (-3.16-fold) compared to control cells. CONCLUSION: Both rosemary extracts, carnosol and carnosic acid, exert potential cytotoxic effects on the HEp-2 cell line via inhibition of the COX-2 pathway. The combination of carnosol and carnosic acid exerts a stronger cytotoxic effect than either compound alone.
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Antineoplásicos/farmacología , Inhibidores de la Ciclooxigenasa 2/farmacología , Ciclooxigenasa 2/metabolismo , Neoplasias de Cabeza y Cuello/tratamiento farmacológico , Fitoquímicos/farmacología , Rosmarinus/química , Carcinoma de Células Escamosas de Cabeza y Cuello/tratamiento farmacológico , Antineoplásicos/química , Antineoplásicos/aislamiento & purificación , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Inhibidores de la Ciclooxigenasa 2/química , Inhibidores de la Ciclooxigenasa 2/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Neoplasias de Cabeza y Cuello/metabolismo , Neoplasias de Cabeza y Cuello/patología , Células Hep G2 , Humanos , Simulación del Acoplamiento Molecular , Estructura Molecular , Fitoquímicos/química , Fitoquímicos/aislamiento & purificación , Carcinoma de Células Escamosas de Cabeza y Cuello/metabolismo , Carcinoma de Células Escamosas de Cabeza y Cuello/patología , Relación Estructura-Actividad , Células Tumorales CultivadasRESUMEN
BACKGROUND: Research into amisulpride use in Alzheimer's disease (AD) implicates blood-brain barrier (BBB) dysfunction in antipsychotic sensitivity. Research into BBB transporters has been mainly directed towards the ABC superfamily, however, solute carrier (SLC) function in AD has not been widely studied. This study tests the hypothesis that transporters for organic cations contribute to the BBB delivery of the antipsychotics (amisulpride and haloperidol) and is disrupted in AD. METHODS: The accumulation of [3H]amisulpride (3.7-7.7 nM) and [3H]haloperidol (10 nM) in human (hCMEC/D3) and mouse (bEnd.3) brain endothelial cell lines was explored. Computational approaches examined molecular level interactions of both drugs with the SLC transporters [organic cation transporter 1 (OCT1), plasma membrane monoamine transporter (PMAT) and multi-drug and toxic compound extrusion proteins (MATE1)] and amisulpride with the ABC transporter (P-glycoprotein). The distribution of [3H]amisulpride in wildtype and 3×transgenic AD mice was examined using in situ brain perfusion experiments. Western blots determined transporter expression in mouse and human brain capillaries . RESULTS: In vitro BBB and in silico transporter studies indicated that [3H]amisulpride and [3H]haloperidol were transported by the influx transporter, OCT1, and efflux transporters MATE1 and PMAT. Amisulpride did not have a strong interaction with OCTN1, OCTN2, P-gp, BCRP or MRP and could not be described as a substrate for these transporters. Amisulpride brain uptake was increased in AD mice compared to wildtype mice, but vascular space was unaffected. There were no measurable changes in the expression of MATE1, MATE2, PMAT OCT1, OCT2, OCT3, OCTN1, OCTN2 and P-gp in capillaries isolated from whole brain homogenates from the AD mice compared to wildtype mice. Although, PMAT and MATE1 expression was reduced in capillaries obtained from specific human brain regions (i.e. putamen and caudate) from AD cases (Braak stage V-VI) compared to age matched controls (Braak stage 0-II). CONCLUSIONS: Together our research indicates that the increased sensitivity of individuals with Alzheimer's to amisulpride is related to previously unreported changes in function and expression of SLC transporters at the BBB (in particular PMAT and MATE1). Dose adjustments may be required for drugs that are substrates of these transporters when prescribing for individuals with AD.
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Enfermedad de Alzheimer/metabolismo , Amisulprida/farmacología , Antipsicóticos/farmacología , Barrera Hematoencefálica/efectos de los fármacos , Barrera Hematoencefálica/metabolismo , Proteínas de Transporte de Membrana/farmacología , Anciano de 80 o más Años , Animales , Sitios de Unión , Línea Celular , Células Endoteliales/efectos de los fármacos , Células Endoteliales/metabolismo , Femenino , Haloperidol/farmacología , Humanos , Masculino , Proteínas de Transporte de Membrana/química , Ratones , Ratones Transgénicos , Modelos BiológicosRESUMEN
Cells undergo autophagy to save themselves from injury, but progressive autophagy can cause cell death. This study characterized and compared the effect of grape (resveratrol) and tomato (lycopene) extracts and their combination on modulating autophagy-related miRNA and its target gene in squamous cell carcinoma cell line. Docking analysis for extracts and selected genes was performed. Methyl Thiazol Tetrazolium assays were used to assess the cytotoxicity of extracts and their combination toward HEp-2 cells. qRT-PCR was used to quantify changes in gene expression. Data were statistically analyzed. miRNA-20a was identified as a potential effector in laryngeal cancer, and sequestosome-1 (SQSTM1) was its target gene. Docking analysis showed that resveratrol interacted with miRNA-20a and showed less affinity toward SQSTM1. Hydrogen bonds and hydrophobic interactions were predicted. In contrast, lycopene showed less affinity toward miRNA-20a than resveratrol. Increasing doses of resveratrol, lycopene, and their combination induced a statistically significant reduction in mean percent viability and mean fold changes of miRNA-20a and SQSTM1 expression in treated HEp-2 cells. Pearson's correlation showed a statistically significant positive correlation between miRNA-20a and SQSTM1 (R=0.812, p≤0.001). Grape and tomato extracts and their combination display promising cytotoxicity against HEp-2 cells in a dose- and time-dependent fashion. Both extracts reduce the expression of miRNA-20a and SQSTM1 with subsequent inhibition autophagy and promotion of apoptosis in HEp-2 cells.
Las células se someten a autofagia para salvarse de lesiones, pero la autofagia progresiva puede provocar la muerte celular. Este estudio caracterizó y comparó el efecto de los extractos de uva (resveratrol) y tomate (licopeno) y su combinación en la modulación de miARN relacionado con la autofagia y su gen diana en la línea celular de carcinoma de células escamosas. Se realizó análisis de acoplamiento para extractos y genes seleccionados. Se utilizaron ensayos de metil tiazol tetrazolio para evaluar la citotoxicidad de los extractos y su combinación frente a las células HEp-2. qRT-PCR se utilizó para cuantificar los cambios en la expresión génica. Los datos fueron analizados estadísticamente. El miARN-20a se identificó como un efector potencial en el cáncer de laringe y el secuenciasoma-1 (SQSTM1) fue su gen diana. El análisis de acoplamiento mostró que el resveratrol interactuaba con miRNA-20a y mostraba menos afinidad hacia SQSTM1. Se predijeron enlaces de hidrógeno e interacciones hidrofóbicas. Por el contrario, el licopeno mostró menos afinidad hacia el miARN-20a que el resveratrol. El aumento de las dosis de resveratrol, licopeno y su combinación indujo una reducción estadísticamente significativa en el porcentaje medio de viabilidad y los cambios medios en la expresión de miRNA- 20a y SQSTM1 en las células HEp-2 tratadas. La correlación de Pearson mostró una correlación positiva estadísticamente significativa entre miRNA-20a y SQSTM1 (R=0,812, p≤0,001). Los extractos de uva y tomate y su combinación muestran una citotoxicidad prometedora contra las células HEp-2 de forma dependiente de la dosis y el tiempo. Ambos extractos reducen la expresión de miRNA-20a y SQSTM1 con la posterior inhibición de la autofagia y promoción de la apoptosis en células HEp-2.
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The polo-box domain (PBD) has critical roles in the mitotic functions of polo-like kinase 1 (PLK1). The replacement with partial ligand alternative through computational enrichment (REPLACE) strategy to develop inhibitors of protein-protein interactions has identified alternatives for the N-terminal tripeptide of a Cdc25C substrate. In addition, a peptide structure-activity relationship described key determinants and novel information useful for drug design. Fragment-ligated inhibitory peptides (FLIP) were generated with comparable affinity to peptide PBD inhibitors and possessed antiproliferative phenotypes in cells consistent with the observed decrease in PLK1 centrosomal localization. These FLIPs showed evidence of enhanced PLK1 inhibition in cells relative to peptides and induced monopolar and multipolar spindles, which stands in contrast to previously reported small-molecule PBD inhibitors that display phenotypes only partially representative of PLK1 knockdown. Progress obtained applying REPLACE validates this approach for identifying fragment alternatives for determinants of the Cdc25C-binding motif and extends its applicability of the strategy for discovering protein-protein interaction inhibitors. In addition, the described PBD inhibitors retain high specificity for PLK1 over PLK3 and therefore show promise as isotype selective, non-ATP competitive kinase inhibitors that provide new impetus for the development of PLK1-selective antitumor therapeutics.