RESUMEN
Chaperone Mediated Autophagy (CMA) is a selective autophagy pathway deregulated in many cancers. In this study, we were aiming at understanding the importance of CMA in breast cancer. To this end, we examined the expression of the CMA markers HSP8 and LAMP2A in different breast cancer cell lines and found a wide range of LAMP2A expression levels across the cell lines analyzed. Next, we applied a specific immunohistochemical staining protocol to a tissue microarray derived from a cohort of 365 breast cancer patients. Therefore, we were able to find a correlation of high LAMP2A but not HSPA8 (HSC70) with worse disease free survival in patients with HER2 negative tumors (p = 0.026) which was independent prognostic parameter from pT category, pN category and grading in a multivariate model (HR = 1.889; 95% CI = 1.039-3.421; p = 0.037). In line, low LAMP2A levels decrease proliferation of the breast cancer cell lines T47D and MCF-7 in vitro. Our data suggest that LAMP2A supports a more severe breast cancer cell phenotype.
Asunto(s)
Neoplasias de la Mama/metabolismo , Técnicas de Cultivo de Célula/métodos , Proteína 2 de la Membrana Asociada a los Lisosomas/metabolismo , Receptor ErbB-2/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Western Blotting , Neoplasias de la Mama/genética , Neoplasias de la Mama/terapia , Línea Celular Tumoral , Proliferación Celular/genética , Supervivencia Celular/genética , Autofagia Mediada por Chaperones/genética , Supervivencia sin Enfermedad , Femenino , Humanos , Proteína 2 de la Membrana Asociada a los Lisosomas/genética , Células MCF-7 , Persona de Mediana Edad , Interferencia de ARNRESUMEN
Macroautophagy (herein referred to as autophagy) is a complex catabolic process characterized by the formation of double-membrane vesicles called autophagosomes. During this process, autophagosomes engulf and deliver their intracellular content to lysosomes, where they are degraded by hydrolytic enzymes. Thereby, autophagy provides energy and building blocks to maintain cellular homeostasis and represents a dynamic recycling mechanism. Importantly, the clearance of damaged organelles and aggregated molecules by autophagy in normal cells contributes to cancer prevention. Therefore, the dysfunction of autophagy has a major impact on the cell fate and can contribute to tumorigenesis. Breast cancer is the most common cancer in women and has the highest mortality rate among all cancers in women worldwide. Breast cancer patients often have a good short-term prognosis, but long-term survivors often experience aggressive recurrence. This phenomenon might be explained by the high heterogeneity of breast cancer tumors rendering mammary tumors difficult to target. This review focuses on the mechanisms of autophagy during breast carcinogenesis and sheds light on the role of autophagy in the traits of aggressive breast cancer cells such as migration, invasion, and therapeutic resistance.
Asunto(s)
Autofagia , Neoplasias de la Mama/patología , Carcinogénesis/patología , Transformación Celular Neoplásica , Animales , Línea Celular Tumoral , Femenino , Humanos , Recurrencia Local de NeoplasiaRESUMEN
ALK inhibitors effectively target EML4-ALK positive non-small cell lung cancer, but their effects are hampered by treatment resistance. In the present study, we asked whether ALK inhibition affects autophagy, and whether this may influence treatment response. Whereas the impact of targeted therapies on autophagic activity previously have been assessed by surrogate marker proteins such as LC3B, we here thoroughly examined effects on functional autophagic activity, i.e. on the sequestration and degradation of autophagic cargo, in addition to autophagic markers. Interestingly, the ALK inhibitor Ceritinib decreased mTOR activity and increased GFP-WIPI1 dot formation in H3122 and H2228 EML4-ALK+ lung cancer cells, suggesting autophagy activation. Moreover, an mCherry-EGFP-LC3B based assay indicated elevated LC3B carrier flux upon ALK inhibition. In accordance, autophagic cargo sequestration and long-lived protein degradation significantly increased upon ALK inhibition. Intriguingly, autophagic cargo flux was dependent on VPS34 and ULK1, but not LC3B. Co-treating H3122 cells with Ceritinib and a VPS34 inhibitor or Bafilomycin A1 resulted in reduced cell numbers. Moreover, VPS34 inhibition reduced clonogenic recovery of Ceritinib-treated cells. In summary, our results indicate that ALK inhibition triggers LC3B-independent macroautophagic flux in EML4-ALK+ cells to support cancer cell survival and clonogenic growth.
Asunto(s)
Quinasa de Linfoma Anaplásico/antagonistas & inhibidores , Antineoplásicos/farmacología , Autofagia/efectos de los fármacos , Carcinoma de Pulmón de Células no Pequeñas/inmunología , Neoplasias Pulmonares/inmunología , Proteínas de Fusión Oncogénica/metabolismo , Pirimidinas/farmacología , Sulfonas/farmacología , Homólogo de la Proteína 1 Relacionada con la Autofagia/metabolismo , Carcinoma de Pulmón de Células no Pequeñas/enzimología , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Fosfatidilinositol 3-Quinasas Clase III/antagonistas & inhibidores , Fosfatidilinositol 3-Quinasas Clase III/metabolismo , Humanos , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Neoplasias Pulmonares/enzimología , Neoplasias Pulmonares/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismoRESUMEN
[This corrects the article DOI: 10.1155/2020/8506572.].
RESUMEN
LAMP2A and HSC70 are crucial players in chaperone-mediated autophagy (CMA), a targeted, lysosome-dependent protein degradation pathway. Elevated LAMP2A levels, indicative of increased CMA activity, are observed in several malignancies, and CMA downregulation may be exploited therapeutically. We evaluated the impact of LAMP2A and HSC70 in pulmonary squamous cell carcinomas (pSQCC). Antibodies were validated by knockdown and overexpression experiments using three different cell lines. Expression levels in tissue were analyzed by immunohistochemistry in a cohort of 336 consecutive pSQCC using tissue microarrays. There was no significant correlation between the two markers among each other and no association with pathological parameters (TNM categories, grading). However, both high LAMP2A and HSC70 expression were associated with worse outcome, including overall survival (OS; p = 0.012 and p = 0.001) and disease free survival (DFS; p = 0.049 and p = 0.036). In multivariate analysis, both markers and a combination of them were independent adverse prognostic factors for OS (LAMP2Ahigh: HR = 2.059; p < 0.001; HSC70high: HR = 1.987; p < 0.001; LAMP2Ahigh/HSC70high: HR = 1.529; p < 0.001) and DFS (LAMP2Ahigh: HR = 1.709; p = 0.004; HSC70high: HR = 1.484; p = 0.027; LAMP2Ahigh/HSC70high: HR = 1.342, p < 0.001). The negative prognostic impact of high LAMP2A and HSC70 and their variable expression in pSQCC may justify the use of these proteins as potential biomarkers for future CMA-inhibiting therapies.