Mutational landscape of the essential autophagy gene BECN1 in human cancers

Area of Science:

• Molecular Biology
• Cancer Genetics
• Cellular Biology

Background:

• Macroautophagy (autophagy) plays a dual role in cancer, potentially suppressing or promoting tumor growth.
• The autophagy gene ATG6/BECN1, encoding Beclin1, was previously suggested to be a tumor suppressor, particularly in breast, ovarian, and prostate cancers.
• The close proximity of BECN1 to the BRCA1 gene on chromosome 17q21 complicated previous assessments of BECN1's tumor suppressor status.

Purpose of the Study:

• To investigate the mutational status of BECN1 in human cancers.
• To clarify the role of BECN1 in tumorigenesis, particularly in light of its association with BRCA1.
• To determine if BECN1 functions as a tumor suppressor across various human cancers.

Main Methods:

• Analysis of human tumor sequencing data from The Cancer Genome Atlas (TCGA) and other databases.
• Assessment of the mutational status and large deletions encompassing BECN1.
• Comparative analysis of BECN1 and BRCA1 deletions in breast and ovarian cancers.

Main Results:

• Large deletions involving both BRCA1 and BECN1, as well as deletions of BRCA1 alone, were observed in breast and ovarian cancers.
• These findings suggest BRCA1 loss is a primary driver mutation in these cancers.
• No significant evidence of BECN1 mutation or loss was found in any other assessed cancer type.

Conclusions:

• BECN1 is not significantly mutated in human cancer.
• Contrary to prior reports, BECN1 does not function as a tumor-suppressor gene in most human cancers.
• The observed deletions involving BECN1 in conjunction with BRCA1 deletions are likely attributable to BRCA1's primary role as a tumor suppressor.