Overexpression SPRY2 Suppresses Esophageal Squamous Cell Carcinoma Progression Via Inactivation of ERK/AKT Signaling / La Sobreexpresión SPRY2 Suprime la Evolución del Carcinoma de Células Escamosas de Esófago Mediante la Inactivación de la Señalización ERK/AKT

SUMMARY: Esophageal cancer is one of the most aggressive gastrointestinal cancers. Invasion and metastasis are the main causes of poor prognosis of esophageal cancer. SPRY2 has been reported to exert promoting effects in human cancers, which controls signal pathways including PI3K/AKT and MAPKs. However, the expression of SPRY2 in esophageal squamous cell carcinoma (ESCC) and its underlying mechanism remain unclear. In the present study, we aimed to investigate the detailed role of SPRY2 in the regulation of cell proliferation, invasion and ERK/AKT signaling pathway in ESCC. It was identified that the expression level of SPRY2 in ESCC was remarkably decreased compared with normal tissues, and it was related to clinicopathologic features and prognosis ESCC patients. The upregulation of SPRY2 expression notably inhibited the proliferation, migration and invasion of Eca-109 cells. In addition, the activity of ERK /AKT signaling was also suppressed by the SPRY2 upregulation in Eca-109 cells. Our study suggests that overexpression of SPRY2 suppress cancer cell proliferation and invasion of by through suppression of the ERK/AKT signaling pathways in ESCC. Therefore, SPRY2 may be a promising prognostic marker and therapeutic target for ESCC.

El cáncer de esófago es uno de los cánceres gastrointestinales más agresivos. La invasión y la metástasis son las principales causas de mal pronóstico del cáncer de esófago. Se ha informado que SPRY2 ejerce efectos promotores en los cánceres humanos, que controla las vías de señales, incluidas PI3K/AKT y MAPK. Sin embargo, la expresión de SPRY2 en el carcinoma de células escamosas de esófago (ESCC) y su mecanismo subyacente aún no están claros. En el presente estudio, nuestro objetivo fue investigar el papel detallado de SPRY2 en la regulación de la proliferación celular, la invasión y la vía de señalización ERK/AKT en ESCC. Se identificó que el nivel de expresión de SPRY2 en ESCC estaba notablemente disminuido en comparación con los tejidos normales, y estaba relacionado con las características clínico-patológicas y el pronóstico de los pacientes con ESCC. La regulación positiva de la expresión de SPRY2 inhibió notablemente la proliferación, migración e invasión de células Eca-109. Además, la actividad de la señalización de ERK/AKT también fue suprimida por la regulación positiva de SPRY2 en las células Eca-109. Nuestro estudio sugiere que la sobreexpresión de SPRY2 suprime la proliferación y la invasión de células cancerosas mediante la supresión de las vías de señalización ERK/AKT en ESCC. Por lo tanto, SPRY2 puede ser un marcador de pronóstico prometedor y un objetivo terapéutico para la ESCC.

Role of MicroRNA-21 in Proliferation and Migration of Pancreatic Cancer Cells / 胃肠病学

Background: Studies have shown that microRNAs are closely related to the occurrence and development of tumors. As one of the most common carcinogenic microRNAs, the specific role and mechanism of miR-21 in the proliferation and migration of pancreatic cancer cells have not been fully elucidated. Aims: To investigate the effect and specific molecular mechanism of miR-21 on proliferation and migration of pancreatic cancer cells. Methods: PANC-1 and MIA PaCa-2 cells were transfected with lentiviral vectors to construct stable cell lines with overexpression and knockdown of miR-21, respectively. The transfection efficiency was verified by qRT-PCR. CCK-8 assay was used to detect cell proliferation, scratch test was used to detect cell migration ability. The expressions of Spry2 mRNA and protein were determined by qRT-PCR and Western blotting, respectively, and luciferase report assay was used to detect the regulatory effect of miR-21 on Spry2. Results: Overexpression of miR-21 significantly promoted PANC-1 cells proliferation and migration (P<0.05). Knockdown of miR-21 significantly inhibited MIA PaCa-2 cells proliferation and migration (P<0.05). Compared with controls, expressions of Spry2 mRNA and protein were significantly decreased after up-regulation of miR-21 (P<0.05), however, expressions of Spry2 mRNA and protein were significantly increased after down-regulation of miR-21 (P<0.05). Overexpression of miR-21 could inhibit luciferase activity of plasmids containing wild-type Spry2 3'-UTR sequence (P<0.05), and knockdown of miR-21 could enhance luciferase activity (P<0.05). Spry2 could reverse miR-21-mediated cell proliferation and migration (P<0.05). Conclusions: MiR-21 can affect biological function of pancreatic cancer cells by targeted regulating the expression of Spry2.

Induction of Resistance to BRAF Inhibitor Is Associated with the Inability of Spry2 to Inhibit BRAF-V600E Activity in BRAF Mutant Cells

The clinical benefits of oncogenic BRAF inhibitor therapies are limited by the emergence of drug resistance. In this study, we investigated the role of a negative regulator of the MAPK pathway, Spry2, in acquired resistance using BRAF inhibitor-resistant derivatives of the BRAF-V600E melanoma (A375P/Mdr). Real-time RT-PCR analysis indicated that the expression of Spry2 was higher in A375P cells harboring the BRAF V600E mutation compared with wild-type BRAF-bearing cells (SK-MEL-2) that are resistant to BRAF inhibitors. This result suggests the ability of BRAF V600E to evade feedback suppression in cell lines with BRAF V600E mutations despite high Spry2 expression. Most interestingly, Spry2 exhibited strongly reduced expression in A375P/Mdr cells with acquired resistance to BRAF inhibitors. Furthermore, the overexpression of Spry2 partially restored sensitivity to the BRAF inhibitor PLX4720 in two BRAF inhibitor-resistant cells, indicating a positive role for Spry2 in the growth inhibition induced by BRAF inhibitors. On the other hand, long-term treatment with PLX4720 induced pERK reactivation following BRAF inhibition in A375P cells, indicating that negative feedback including Spry2 may be bypassed in BRAF mutant melanoma cells. In addition, the siRNA-mediated knockdown of Raf-1 attenuated the rebound activation of ERK stimulated by PLX4720 in A375P cells, strongly suggesting the positive role of Raf-1 kinase in ERK activation in response to BRAF inhibition. Taken together, these data suggest that RAF signaling may be released from negative feedback inhibition through interacting with Spry2, leading to ERK rebound and, consequently, the induction of acquired resistance to BRAF inhibitors.