RESUMEN
Triple negative breast cancer (TNBC) patients exhibit poor survival outcomes and lack effective targeted therapies. Using unbiased in vivo genome-wide CRISPR screening, we interrogated cancer vulnerabilities in TNBC and identified an interplay between oncogenic and tumor suppressor pathways. This study reveals tumor regulatory functions for essential components of the mTOR and Hippo pathways in TNBC. Using in vitro drug matrix synergy models and in vivo patient-derived xenografts, we further establish the therapeutic relevance of our findings and show that pharmacological inhibition of mTORC1/2 and oncoprotein YAP efficiently reduces tumorigenesis in TNBC. At the molecular level, we find that while verteporfin-induced YAP inhibition leads to apoptosis, torin1-mediated mTORC1/2 inhibition promotes macropinocytosis. Torin1-induced macropinocytosis further facilitates verteporfin uptake, thereby greatly enhancing its pro-apoptotic effects in cancer cells. Overall, our study underscores the power and robustness of in vivo CRISPR genome-wide screens in identifying clinically relevant and innovative therapeutic modalities in cancer.
Asunto(s)
Repeticiones Palindrómicas Cortas Agrupadas y Regularmente Espaciadas , Terapia Combinada/métodos , Proteínas Serina-Treonina Quinasas/genética , Serina-Treonina Quinasas TOR/genética , Neoplasias de la Mama Triple Negativas/genética , Animales , Sistemas CRISPR-Cas , Carcinogénesis , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Técnicas de Inactivación de Genes , Células HEK293 , Vía de Señalización Hippo , Humanos , Diana Mecanicista del Complejo 1 de la Rapamicina , Diana Mecanicista del Complejo 2 de la Rapamicina , Ratones , Verteporfina , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Growth factor receptor-bound protein 10 (Grb10) is an adaptor protein that binds to the insulin receptor, upon which insulin signaling and action are thought to be inhibited. Grb10 is also a substrate for the mechanistic target of rapamycin complex 1 (mTORC1) that mediates its feedback inhibition on phosphatidylinositide 3-kinase (PI3K)/Akt signaling. To characterize the function of Grb10 and its regulation by mTORC1 in human muscle, primary skeletal muscle cells were isolated from healthy lean young men and then induced to differentiate into myotubes. Knockdown of Grb10 enhanced insulin-induced PI3K/Akt signaling and glucose uptake in myotubes, reinforcing the notion underlying its function as a negative regulator of insulin action in human muscle. The increased insulin responsiveness in Grb10-silenced myotubes was associated with a higher abundance of the insulin receptor. Furthermore, insulin and amino acids independently and additively stimulated phosphorylation of Grb10 at Ser476. However, acute inhibition of mTORC1 with rapamycin blocked Grb10 Ser476 phosphorylation and repressed a negative-feedback loop on PI3K/Akt signaling that increased myotube responsiveness to insulin. Chronic rapamycin treatment reduced Grb10 protein abundance in conjunction with increased insulin receptor protein levels. Based on these findings, we propose that mTORC1 controls PI3K/Akt signaling through modulation of insulin receptor abundance by Grb10. These findings have potential implications for obesity-linked insulin resistance, as well as clinical use of mTORC1 inhibitors.
Asunto(s)
Proteína Adaptadora GRB10/fisiología , Insulina/fisiología , Diana Mecanicista del Complejo 1 de la Rapamicina/fisiología , Fibras Musculares Esqueléticas/fisiología , Transducción de Señal/genética , Transducción de Señal/fisiología , Aminoácidos/farmacología , Células Cultivadas , Proteína Adaptadora GRB10/genética , Técnicas de Silenciamiento del Gen , Glucosa/metabolismo , Humanos , Insulina/farmacología , Masculino , Diana Mecanicista del Complejo 1 de la Rapamicina/genética , Proteína Oncogénica v-akt/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Fosforilación/efectos de los fármacos , Receptor de Insulina/metabolismo , Adulto JovenRESUMEN
DNA repair mechanisms are crucial for cell survival. It increases the cancer cell's ability to resist DNA damage. FEN1 is involved in DNA replication and repair, specifically long-patch base excision repair. Although the gene function and post-translational modification of FEN1 are well studied, the regulatory mechanism of FEN1 by upstream signal pathways remains unclear. In this article, we have identified AKT as a regulator of FEN1 activity in lung cancer cells. Sustained activation of AKT can phosphorylate nuclear transcription factor NF-κB/p65. NF-κB/p65 directly binds to FEN1 promoter to promote a high transcription level of FEN1, revealing the contribution of the AKT signaling pathway to drug resistance of cancer cells. The combination of an AKT inhibitor and cisplatin efficiently suppressed lung cancer cell growth both in vitro and in vivo Our study illustrated an upstream regulatory mechanism of FEN1, which will contribute to the development of effective lung cancer therapies.These findings identified AKT as a regulator of FEN1 activity and revealed the AKT signaling pathway's contribution to drug resistance, which will contribute to the development of effective lung cancer therapy.
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Antineoplásicos/uso terapéutico , Endonucleasas de ADN Solapado/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Animales , Antineoplásicos/farmacología , Línea Celular Tumoral , Regulación hacia Abajo , Femenino , Humanos , Ratones , Ratones DesnudosRESUMEN
Multiple DNA repair pathways may be involved in the removal of the same DNA lesion caused by endogenous or exogenous agents. Although distinct DNA repair machinery fulfill overlapping roles in the repair of DNA lesions, the mechanisms coordinating different pathways have not been investigated in detail. Here, we show that Ku70, a core protein of nonhomologous end-joining (NHEJ) repair pathway, can directly interact with DNA polymerase-ß (Pol-ß), a central player in the DNA base excision repair (BER), and this physical complex not only promotes the polymerase activity of Pol-ß and BER efficiency but also enhances the classic NHEJ repair. Moreover, we find that DNA damages caused by methyl methanesulfonate (MMS) or etoposide promote the formation of Ku70-Pol-ß complexes at the repair foci. Furthermore, suppression of endogenous Ku70 expression by small interfering RNA reduces BER efficiency and leads to higher sensitivity to MMS and accumulation of the DNA strand breaks. Similarly, Pol-ß knockdown impairs total-NHEJ capacity but only has a slight influence on alternative NHEJ. These results suggest that Pol-ß and Ku70 coordinate 2-way crosstalk between the BER and NHEJ pathways.-Xia, W., Ci, S., Li, M., Wang, M., Dianov, G. L., Ma, Z., Li, L., Hua, K., Alagamuthu, K. K., Qing, L., Luo, L., Edick, A. M., Liu, L., Hu, Z., He, L., Pan, F., Guo, Z. Two-way crosstalk between BER and c-NHEJ repair pathway is mediated by Pol-ß and Ku70.
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Daño del ADN/genética , Reparación del ADN/genética , Replicación del ADN/genética , Autoantígeno Ku/metabolismo , ADN/metabolismo , Roturas del ADN de Doble Cadena , ADN Polimerasa beta/genética , Proteínas de Unión al ADN/metabolismo , HumanosRESUMEN
Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide. 5-Fluorouracil (5-FU) is widely used in the treatment of cancers, but its antineoplastic activity is limited in drug-resistant cancer cells. To investigate the detailed mechanism of 5-FU resistance, we developed a model of 5-FU-resistant cells from HCT-8 cells, a well-established colorectal cancer cell line. We found that the drug-resistant cells demonstrated high expression of TCF4 and ß-catenin, indicating an upregulated Wnt pathway. A microarray analysis revealed that the suppression of the checkpoint kinase 1 (CHK1) pathway explained the resistance to 5-FU, especially in p53 wild-type cancer cells such as HCT-8. Our data also demonstrated that the CHK1 pathway is suppressed by the Wnt pathway in 5-FU-resistant cells. In summary, we have discovered a novel mechanism for 5-FU resistance mediated by histone deacetylation, which also revealed the crosstalk between the Wnt pathway and CHK1 pathway.