AMBRA1 attenuates the proliferation of uveal melanoma cells

The multiple roles of autophagy in uveal melanoma and the microenvironment

PURPOSE

Uveal melanoma (UM) is the most common primary malignant intraocular tumor in adults, and effective clinical treatment strategies are still lacking. Autophagy is a lysosome-dependent degradation system that can encapsulate abnormal proteins, damaged organelles. However, dysfunctional autophagy has multiple types and plays a complex role in tumorigenicity depending on many factors, such as tumor stage, microenvironment, signaling pathway activation, and application of autophagic drugs.

METHODS

A systematic review of the literature was conducted to analyze the role of autophagy in UM, as well as describing the development of autophagic drugs and the link between autophagy and the tumor microenvironment.

RESULTS

In this review, we summarize current research advances regarding the types of autophagy, the mechanisms of autophagy, the application of autophagy inhibitors or agonists, autophagy and the tumor microenvironment. Finally, we also discuss the relationship between autophagy and UM.

CONCLUSION

Understanding the molecular mechanisms of how autophagy differentially affects tumor progression may help to design better therapeutic regimens to prevent and treat UM.

Ambra1 modulates the sensitivity of mantle cell lymphoma to palbociclib by regulating cyclin D1

Mantle cell lymphoma (MCL) is a rare B-cell malignancy with a predominantly aggressive clinical course and poor prognosis. Abnormal expression of Ambra1 is closely related to the occurrence and development of various tumors. However, the role of Ambra1 in MCL remains unknown. Here, we performed both in vitro and in vivo experiments to investigate how Ambra1 regulates MCL progression and whether Ambra1 modulates the sensitivity of MCL cells to the CDK4/6 inhibitor palbociclib. We discovered that MCL cells had decreased levels of Ambra1 expression relative to normal B cells. Overexpression of Ambra1 in MCL cells inhibited autophagy, reduced cell proliferation, migration, and invasion, and decreased cyclin D1 level. While knockdown of Ambra1 reduced MCL cell sensitivity to CDK4/6 inhibitor palbociclib. Furthermore, overexpression of cyclin D1 lowered the sensitivity of MCL cells to palbociclib, enhanced cell proliferation, migration, invasion, and autophagy, and inhibited cell apoptosis. When Ambra1 expression was inhibited, the in vivo antitumor effects of palbociclib on MCL were reversed. Ambra1 expression was downregulated but cyclin D1 expression was upregulated in MCL samples, demonstrating a negative correlation between Ambra1 and cyclin D1. Our findings suggest a unique tumor suppressor function for Ambra1 in the development of MCL.

RUVBL1-modulated chromatin remodeling alters the transcriptional activity of oncogenic CTNNB1 in uveal melanoma

Recent years have witnessed an increasing research interest in the therapeutic value of aberrant chromatin regulatory processes in carcinogenesis. Our study was performed to explore the possible carcinogenic mechanism of the chromatin regulator RuvB-like protein 1 (RUVBL1) in uveal melanoma (UVM). The expression pattern of RUVBL1 was retrieved in bioinformatics data. The correlation between RUVBL1 expression and the prognosis of patients with UVM was analyzed in publicly available database. The downstream target genes of RUVBL1 were predicted and further verified by co-immunoprecipitation. The bioinformatics analysis results showed that RUVBL1 may be associated with the transcriptional activity of CTNNB1 by regulating chromatin remodeling, and that RUVBL1 functioned as an independent prognostic factor for patients with UVM. The UVM cells manipulated with RUVBL1 knockdown were introduced for in vitro investigation. CCK-8 assay, flow cytometry, scratch assay, Transwell assay and Western blot analysis were used for detection on the resultant UVM cell proliferation, apoptosis, migration, invasion and cell cycle distribution. In vitro cell experimental data showed that RUVBL1 expression was significantly increased in UVM cells and RUVBL1 knockdown inhibited the proliferation, invasion and migration of UVM cells, accompanied by augmented apoptosis rate and blocked cell cycle progression. To sum up, RUVBL1 enhances the malignant biological characteristics of UVM cells by increasing the chromatin remodeling and subsequent transcription activity of CTNNB1.

Ambra1 in cancer: implications for clinical oncology

Activating molecule in Beclin-1-regulated autophagy protein 1 (Ambra1) is well known to mediate the autophagy process and promote the formation of autophagosomes. In addition, Ambra1 is involved in the execution of apoptosis. A growing number of studies have revealed that this protein modifies the sensitivity of cancer cells to anticancer drugs by controlling the balance between autophagy and apoptosis. In addition, Ambra1 is a key factor in regulating the cell cycle, proliferation, invasion and migration. Therefore, it plays a key role in tumorigenesis and progression. Moreover, Ambra1 is highly expressed in a variety of cancers and is closely related to the prognosis of patients. Thus, it appears that Ambra1 has multiple roles in tumorigenesis and progression, which may have implications for clinical oncology. The present review focuses on recent advances in the study of Ambra1, especially the role of the protein in tumorigenesis, progression and effects on anticancer drug sensitivity.