BRAF inhibitor treatment of melanoma causing colonic polyps: An alternative hypothesis

Area of Science:

• Oncology
• Gastroenterology
• Molecular Biology

Background:

• BRAF inhibitor treatment for melanoma can lead to colonic polyps.
• The exact mechanism, possibly involving mitogen-activated protein (MAP)-kinase pathway activation or APC gene mutations, is under investigation.
• An alternative pathway for colorectal cancer (CRC) development involves serrated polyps.

Purpose of the Study:

• To propose a novel hypothesis linking BRAF inhibitor-induced colonic polyps to the serrated polyp pathway.
• To explore the phenotypic and molecular characteristics of BRAF inhibitor-induced polyps in comparison to serrated polyps.

Main Methods:

• Comparative analysis of molecular and histological features of BRAF inhibitor-induced polyps and serrated polyps.
• Review of existing literature on BRAF inhibitors, colonic polyps, and serrated polyp pathway.

Main Results:

• BRAF inhibitor-induced polyps exhibit similarities to serrated polyps, including CpG island methylation phenotype and MLH1 silencing.
• Serrated polyps are characterized by BRAF mutations, MLH1 silencing, and cellular senescence.
• BRAF inhibitor-induced polyps may mimic serrated polyps but involve C-RAF homodimers and B-RAF:C-RAF heterodimers instead of BRAF mutations.

Conclusions:

• BRAF inhibitor-induced colonic polyps may arise through a pathway resembling the serrated polyp pathway.
• The mechanism involves the induction of C-RAF and B-RAF dimers, distinct from the BRAF mutations typically seen in serrated polyps.