Papel de la cinasa de adhesión focal (FAK) en el mecanismo de sensibilidad a tratamientos antiangiogénicos en modelos preclínicos de cáncer colorrectal

Tesis Doctoral inédita leída en la Universidad Autónoma de Marid, Facultad de Medicina, Departamento de Bioquímica. Fecha de Lectura: 14-12-2018El cáncer colorrectal es la principal causa de muerte por cáncer en España y de las primeras causas a nivel mundial. Un alto porcentaje de los pacientes serán diagnosticados en etapas avanzadas de la enfermedad y serán tratados con quimioterapia paliativa, así como con terapia dirigida a dianas específicas como es el caso de bevacizumab y aflibercept que van dirigidas contra miembros de la familia de factores de crecimiento del endotelio vascular (VEGF). A pesar de estas alternativas terapéuticas, desafortunadamente, actualmente no contamos en la práctica clínica con biomarcadores que puedan predecir la respuesta al tratamiento anti-VEGF y nos permitan seleccionar que pacientes podrían beneficiarse de estos tratamientos. La cinasa de adhesión focal (FAK) es una proteína que sirve de anclaje y activa al resto de las proteínas que forman las adhesiones focales y están encargadas de mantener a la célula unida a la matriz extracelular, así como de mantener el contacto célula-célula. FAK está involucrada en múltiples mecanismos celulares de supervivencia como la proliferación, motilidad y migración, así como, también se ha descrito su relevancia en la muerte celular mediada por anoikis. Diversos estudios han demostrado su relevancia en el proceso de angiogénesis, necesario para la supervivencia de la célula tumoral y el desarrollo del tumor. En la presente tesis doctoral hemos evaluado, mediante modelos de xenoinjerto usando líneas de cáncer colorrectal humano, el papel de FAK como mediador en la respuesta a terapias anti- VEGF (bevacizumab y aflibercept). En estos modelos animales hemos observado que aquellos que eran sensibles a los tratamientos mostraban una pérdida de la proteína total de FAK que podría estar relacionada con la apoptosis mediada por anoikis. Por otro lado, el modelo resistente a bevacizumab presentó una ausencia completa de la expresión de FAK en las células epiteliales. Dicha pérdida se produjo durante el desarrollo tumoral previo a recibir el tratamiento anti-VEGF, ya que el grupo de animales control también presentaba esta característica. Mientras que la línea celular con la que se desarrolló el modelo de xenoinjerto sobreexpresaba FAK antes de ser inoculada en los ratones. El estudio del mecanismo por el cual FAK se reduce queda pendiente de confirmar a tiempos más cortos de tratamiento ya que la proteasa y ubiquitina ligasa analizadas muestran una expresión reducida a tiempo final de tratamiento. Posiblemente, y tal y como sugieren otros estudios, sea debido a que la actuación de estas proteínas es un evento temprano dentro de la muerte celular. Nuestros resultados sugieren que la presencia de FAK es necesaria para que los fármacos anti-VEGF activen un mecanismo de muerte celular por anoikis mediado por la degradación de esta proteína mientras que la ausencia de FAK en la células tumorales imposibilitaría la inducción de dicho mecanismo y estaría relacionado con la resistencia o menor sensibilidad a los tratamientos usados. Los resultados de nuestro trabajo abren la posibilidad de continuar la línea de investigación para profundizar en el papel de FAK como mecanismo de sensibilidad al tratamiento anti-VEGF.Colorectal cancer is the leading cause of death in Spain and one of the first worldwide. A high percentage of patients are diagnosed at late stages and, they are treated with palliative therapy and with biologic treatments against specific targets such as members of vascular endothelial growth factor (VEGF) family. Nowadays, despite these therapies, there are no available biomarkers to predict treatment response and therefore to select which patients could be benefited from these therapies. Focal adhesion kinase (FAK) is an assembly protein; it has been involved in activating the rest of focal adhesion proteins to maintain the interactions between cell and extracellular matrix or the cell to cell connections. FAK is involved in multiple cellular survival mechanisms such as proliferation, motility and migration, as well as it has been describing its relevance in cell death mediated by anoikis. Several studies have demonstrated its importance in angiogenesis. In the present doctoral thesis, we have evaluated, through xenograft models using human colorectal cancer lines, the role of FAK as a mediator in the response to anti-VEGF therapies (bevacizumab and aflibercept). In these animal models we have observed that those that were sensitive to the treatments showed a loss of the FAK protein that could be related to the apoptosis mediated by anoikis. On the other hand, the animal model resistant to bevacizumab showed a loss of FAK expression in the epithelial cells during the tumor development prior to receiving the anti-VEGF treatment, since the group of control animals also had this characteristic. However, the cell line used to develope the xenograft overexpressed FAK before being inoculated into mice. The study of the mechanism by which FAK is reduced remains to be confirmed at shorter time since the protease and ubiquitin ligase analyzed show reduced expression at the end of treatment. Possibly, and as other studies suggest, it is because the role of these proteins is an early event within cell death. Our results suggest that FAK is necessary for the anti-VEGF drugs to activate a mechanism of cell death by anoikis mediated by the degradation of this protein. While the absence of FAK in the tumor cells would avoid the induction of this mechanism and would be related to resistance or less sensitivity to anti-VEGF therapies. Results reported in this thesis highlight the remarkable role of FAK in the anti-VEGF sensitivity-related mechanism and are the starting point for further studies which strengthen these novel data

An overview of resistance to chemotherapy in osteosarcoma and future perspectives

Osteosarcoma (OS) is the most common type of bone sarcoma. Despite the availability of multimodal treatment with surgery and chemotherapy, the clinical results remain unsatisfactory. The main reason for the poor outcomes in patients with OS is the development of resistance to methotrexate, cisplatin, doxorubicin, and ifosfamide. Molecular and cellular mechanisms associated with resistance to chemotherapy include DNA repair and cell-cycle alterations, enhanced drug efflux, increased detoxification, resistance to apoptosis, autophagy, tumor extracellular matrix, and angiogenesis. This versatility of cells to generate chemoresistance has motivated the use of anti-angiogenic therapy based on tyrosine kinase inhibitors. This approach has shown that other therapies, along with standard chemotherapy, can improve responses to therapy in patients with OS. Moreover, microRNAs may act as predictors of drug resistance in OS. This review provides insight into the molecular and cellular mechanisms involved in the development of resistance during the treatment of OS and discusses promising novel therapies (e.g., afatinib and palbociclib) for overcoming resistance to chemotherapy in OS

Adjuvant endocrine therapy for premenopausal women with breast cancer: Patient adherence and physician prescribing practices in Mexico

Background: In resource-constrained settings, data regarding breast cancer patients' adherence to endocrine therapy (ET) and physicians’ prescribing practices is limited. This study aims to decrease this knowledge gap in a real-world clinical practice. Methods: Premenopausal women with stage 0-III hormone-sensitive breast cancer and receiving adjuvant ET during the past 1–5 years were identified in three Mexican referral centers. Participants' self-reported ET compliance, clinicopathologic characteristics, ET-related knowledge and beliefs, experienced adverse effects, social support, and patient-physician relationships were evaluated. Physician ET prescribing practices were compared with the gold standard according to international and national guidelines to assess clinicians’ adherence to standard-of-care prescription. Results: In total, 95/132 (72%) and 35/132 (27%) participants reported complete and acceptable adherence, respectively. Incomplete adherence was mainly attributed to forgetfulness, adverse effects, and unwillingness to take ET. Being employed/studying (p = 0.042), worrying about long-term ET use (p = 0.031), and experiencing >7 ET-related symptoms (p = 0.018) were associated with incomplete adherence. Guideline-endorsed regimens were prescribed in 84/132 (64%) patients, while the rest should have undergone ovarian function suppression (OFS) but instead received tamoxifen monotherapy. Conclusions: Premenopausal Mexican women self-report remarkably high rates of adequate ET adherence. However, a considerable proportion misses ≥1 doses/month, usually because of forgetfulness. Notably, only 64% receive standard-of-care ET due to suboptimal prescription of OFS. Interventions that remind patients to take their ET, refine physicians’ knowledge on the importance of OFS in high-risk patients, and increase access to OFS could prove pivotal to enhance optimal ET implementation and adherence, which could translate into improved patient outcomes

Additional file 1: Table S1. of Predictive value of vrk 1 and 2 for rectal adenocarcinoma response to neoadjuvant chemoradiation therapy: a retrospective observational cohort study

Relationship between clinicopathological characteristics and biomarkers. (DOCX 21 kb