Investigação das quinases Aurora A e Aurora B na tumorigenicidade mediada pelo oncogene KRAS / Investigation of Aurora kinases A and B in KRAS-induced lung tumorigenesis

O câncer de pulmão é a principal causa de morte relacionada ao câncer no mundo. Mutações em KRAS são altamente prevalentes no câncer e têm sido diretamente associadas ao processo tumorigênico. Apesar disso, até hoje todas as terapias visando inibir KRAS diretamente falharam e a caracterização de alvos indiretos, importantes para a oncogênese mediada por KRAS, é fundamental para o desenvolvimento de novas terapias contra o câncer de pulmão. Nós mostramos previamente que as quinases Aurora A (AURKA) e B (AURKB) são alvos a jusante de KRAS, importantes para o crescimento, viabilidade e oncogenicidade de linhagens celulares derivadas de tumores pulmonares mediados por KRAS. Aqui, nós aprofundamos os nossos estudos para melhor caracterizar AURKA e AURKB como potenciais alvos terapêuticos no câncer de pulmão. Os objetivos deste trabalho foram (1) investigar o mecanismo de perda de viabilidade induzido pela inibição de AURKA e/ou AURKB; (2) avaliar como a inibição de AURKA e/ou AURKB afeta propriedades oncogênicas relacionadas à agressividade tumoral; e (3) como a inibição destas quinases afeta o crescimento tumoral in vivo. Para tanto, nós utilizamos dois modelos celulares: (1) células A549 e H358, que apresentam mutações em KRAS, geneticamente modificadas para a expressão estável e induzível de shRNAs contra AURKA ou AURKB, e (2) células tumorais H1703, que não apresentam mutações em KRAS, geneticamente modificadas para a expressão induzível de KRASG12V, tratadas ou não com inibidores farmacológicos das quinases Aurora. A inibição farmacológica ou por interferência de RNA de AURKA e/ou AURKB em células H358 e A549 reduziu a proliferação celular, sendo esta inibição acompanhada de anomalias mitóticas, além de aneuploidia e poliploidia. A inibição destas quinases também induziu morte celular in vitro, tanto em mitose, quanto em interfase. Mais interessantemente, a inibição farmacológica dual de AURKA e AURKB induziu morte celular in vitro em células H1703, somente na presença de KRASG12V, indicando que a inibição das quinases Aurora afeta preferencialmente células portadoras de mutações em KRAS. Além disso, a inibição de AURKA e/ou AURKB reduziu propriedades malignas celulares relacionadas à agressividade tumoral, como migração, invasão e adesão. Finalmente, a inibição de AURKA por RNA de interferência em células A549 também reduziu a formação de tumores in vivo. Entretanto, como a inibição destas quinases levou a anomalias mitóticas e à instabilidade genética, nós resolvemos investigar se a inibição de TPX2, um substrato e ativador de AURKA, poderia ser uma abordagem alternativa para inibir esta via em câncer de pulmão induzido por KRAS. Primeiramente, nós observamos nos nossos modelos celulares que KRAS regula positivamente a expressão de TPX2. Além disso, a inibição de TPX2 em células pulmonares portadoras de KRAS oncogênica reduziu a viabilidade e proliferação celulares e induziu morte celular. Mais interessantemente, esses efeitos ocorreram preferencialmente em células que expressam KRAS oncogênica. Em conclusão, nossos resultados apoiam a hipótese de que a ativação de AURKA/TPX2 e AURKB por KRAS são eventos importantes no câncer de pulmão e sugerem a inibição destas vias, possivelmente em combinação com outras terapias citotóxicas, como uma nova abordagem terapêutica para o câncer de pulmão induzido por KRAS

Lung cancer is the leading cause of cancer-related deaths worldwide. KRAS mutations are widespread in lung cancer and have been causally linked to tumorigenesis. Nonetheless, therapies targeting KRAS directly have so far failed and characterization of indirect KRAS targets, which play important roles in KRAS-mediated oncogenesis, is crucial for the development of new therapies for lung cancer. We have previously shown that mitotic kinases Aurora A (AURKA) and B (AURKB) are downstream targets of oncogenic KRAS, important for the growth, viability, and oncogenicity of KRAS-transformed lung cancer cell lines. Here, we studied these kinases more in depth in order to better characterize them as potential therapeutical targets for KRAS-induced lung cancer. The aims of this study were (1) to investigate the mechanism leading to loss of viability upon AURKA and/or AURKB targeting; (2) to evaluate how AURKA and/or AURKB inhibition affects malignant properties associated with tumor aggressiveness; and (3) to determine whether AURKA and/or AURKB inhibition reduces KRAS-induced tumor growth in vivo. For that purpose, we used two cell-based models: (1) KRAS mutant A549 and H358 cells with stable and inducible shRNA-mediated knockdown of AURKA or AURKB, and (2) KRAS wildtype H1703 tumor cell lines, genetically engineered to inducibly express oncogenic KRASG12V treated or not with Aurora kinase pharmacological inhibitors. Targeting AURKA and/or AURKB pharmacologically or by RNA interference in H358 and A549 cells led to decreased cell proliferation, which was accompanied by mitotic abnormalities, leading to aneuploidy and hyperploidy. Aurora kinase targeting also induced cell death in vitro, both during mitosis and interphase. More importantly, AURKA and AURKB inhibition with a dual pharmacological inhibitor in H1703 cells induced cell death in vitro, but only in the presence of KRASG12V, indicating that Aurora kinase targeting affects preferentially lung cells harboring oncogenic KRAS. Furthermore, AURKA and/or AURKB targeting reduced malignant properties associated with tumor aggressiveness, such as cell migration, invasion and adhesion. Finally, AURKA targeting by RNA interference in A549 cells also reduced growth of xenograft tumors in vivo. Nonetheless, since Aurora targeting was associated with mitotic abnormalities and genetic instability, we decided to investigate if targeting TPX2, a substrate and an activator of AURKA, could constitute an alternative approach to targeting this pathway in KRAS-induced lung cancer. First, using our cell-based models, we determined that KRAS positively regulates TPX2 expression. In addition, TPX2 inhibition by RNA interference in KRAS-positive lung cells reduced cell viability and proliferation and induced cell death. Finally, these effects occurred preferentially in cells harboring oncogenic KRAS. In conclusion, our results support the hypothesis that activation of AURKA/TPX2 and AURKB by KRAS are important events in lung cancer and suggest inhibition of these pathways, possibly in combination with other cytotoxic therapies, as a new approach for KRAS-induced lung cancer therapy

Differential regulation of H3S10 phosphorylation, mitosis progression and cell fate by Aurora Kinase B and C in mouse preimplantation embryos

Coordination of cell division and cell fate is crucial for the successful development of mammalian early embryos. Aurora kinases are evolutionarily conserved serine/threonine kinases and key regulators of mitosis. Aurora kinase B (AurkB) is ubiquitously expressed while Aurora kinase C (AurkC) is specifically expressed in gametes and preimplantation embryos. We found that increasing AurkC level in one blastomere of the 2-cell embryo accelerated cell division and decreasing AurkC level slowed down mitosis. Changing AurkB level had the opposite effect. The kinase domains of AurkB and AurkC were responsible for their different ability to phosphorylate Histone H3 Serine 10 (H3S10P) and regulate metaphase timing. Using an Oct4-photoactivatable GFP fusion protein (Oct4-paGFP) and fluorescence decay after photoactivation assay, we found that AurkB overexpression reduced Oct4 retention in the nucleus. Finally, we show that blastomeres with higher AurkC level elevated pluripotency gene expression, which were inclined to enter the inner cell mass lineage and subsequently contributed to the embryo proper. Collectively, our results are the first demonstration that the activity of mitotic kinases can influence cell fate decisions in mammalian preimplantation embryos and have important implications to assisted reproduction.

Evaluation of target mRNA cleavage by Aurorakinase B specific siRNA in prostate and hepatic cancer cells and its therapeutic potential in mouse models of liver cancer.

The anti proliferative potential of siRNA26, targeted to Aurora kinase B, in prostate cancer cells is known from a previous study from our laboratory. Here we first show that siRNA26 cleaves at the same position of the target mRNA in the prostate cancer and hepatocellular carcinoma cell lines, PC3 and HepG2 respectively. Aurorakinase B specific siRNA, but not a control siRNA, inhibited PC3 and HepG2 cell proliferation and cell migration. These effects correlated to RNA silencing of Aurorakinase B in both the cell lines. Intra-tumoral administration of HiPerfect complexed siRNA26 inhibited the growth of HepG2 xenografts in SCID mice. In an orthotopic setting, intravenous administration of HiPerfect encapsulated siRNA26 appeared to reduce the severity of multifocal lesions.

The research progress of Aurora-B kinase and its inhibitors / 药学学报

Aurora-B as an important kinase to adjust the cell normal mitosis is a potent target for cancer treatment. Aurora-B is overexpressed in a broad range of tumor and tumor cells are more sensitive while Aurora-B is inhibited. Due to the key role of the Aurora-B in cell mitosis, the development of its inhibitors is becoming more and more important. Several small molecules inhibit with a similar efficacy both Aurora-A and Aurora-B, however, in most cases the effects resemble Aurora-B disruption by genetic methods, indicating that Aurora-B represents an effective therapeutic target. There were several Aurora-B kinase inhibitors which had entered the clinics and displayed good antitumor activity. In this review, we will outline the functions of Aurora kinase B in normal cell division and in malignancy. We will focus on recent preclinical and clinical studies that have explored the mechanism of action and clinical effect of Aurora-B inhibitors in cancer treatment.

[Cytotoxic effects of selective inhibitor 'Aurora Kinase B' on viability and metabolic features of human promyelocytic leukemia cell line]

A goal of modern cancer research is to reach targeted therapies with drugs having fewer side effects. AZD1152 is a highly specific inhibitor of Aurora Kinase B, which leads to the programmed cell death by different mechanisms. The aim of this study was to evaluate the effects of AZD1152 on viability and metabolic activity of NB4 cells [APL derived cell line]. The cells were treated with various concentrations of AZD1152. After 24, 48 and 72h treatments, the metabolic activity and viability of inhibitor-treated NB4 cells were assessed using MTT and trypan blue dye exclusion assays, respectively. Data were analyzed by applying student's t-test [Microsoft Excel]. At 25, 50 and 100 nM, AZD1152 reduced the metabolic activity by 9.2, 15.5 and 56.2% [after 24h], 10.3, 19.5 and 59.9% [after 48h], and 17.1, 28.4 and 64.8% [after 72h], respectively. Meanwhile, the percentage of viability was decreased to about 51, 45 and 40% [after 24h], 39, 36 and 30% [after 48h], and 34, 32 and 28% [after 72h], respectively. According to the results, AZD1152 has substantial efficacy on APL cell line and may be applied in some cases, e. g., for patients who have relapse or who become refractory to the conventional chemotherapy. Further studies are needed to show the molecular mechanisms regulating effects of this anti-cancer agent

Expression of Aurora-B in non-small cell lung cancer and its clinical significance / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the expression of Aurora-B in non-small cell lung cancer (NSCLC) tissues and NSCLC cell lines.</p><p><b>METHOD</b>Aurora-B expression was examined using immunohistochemical SP method in 91 stage I and 69 stage II-III NSCLC tissues and 40 adjacent tissues. The mRNA and protein expressions of Aurora-B in NSCLC cell lines (A549, H460 and H1299) were examined by RT-PCR and Western blotting, respectively.</p><p><b>RESULTS</b>The protein expression of Aurora-B was detected in 77.7% (94/121) of the tumor tissues and 9.8% (4/41) of the adjacent tissues, showing a significant difference between them (P<0.01). The positivity rate of Aurora-B protein was not related with the gender and age of NSCLC patients, but with lymph node metastasis, differentiation and histological type of NSCLC (P<0.05). Aurora-B was expressed in all the NSCLC cell lines (A549, H460 and H1299) at both mRNA and protein levels. A549 cells showed the highest expression of Aurora-B.</p><p><b>CONCLUSION</b>Aurora-B protein is highly expressed in NSCLC tissues and cell lines, and may play a crucial role in the invasion, metastasis and development of NSCLC. The mRNA and protein expression levels of Aurora-B differ significantly between different NSCLC cell lines.</p>

Expression of Aurora-B in human glioma tissue and its significance / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the expression of Aurora-B in human glioma tissue and its significance.</p><p><b>METHODS</b>The total RNA was extracted from 41 human glioma tissues and 11 normal brain tissues by Trizol reagent. After reverse transcription of the total RNA into cDNAs, Aurora-B mRNA expressions in these samples were detected by quantitative real-time PCR. The protein expression in these samples was detected using immunohistochemical staining.</p><p><b>RESULTS</b>Aurora-B mRNA and protein expressions were significantly increased in glioma tissues as compared with those in normal brain tissues.</p><p><b>CONCLUSION</b>Aurora-B mRNA and protein show markedly higher expressions in glioma tissue, suggesting that Aurora-B may be one of the malignant biomarkers in the pathogenesis and progression of human glioma.</p>