SIK1, short for salt-inducible kinase 1, is a serine/threonine protein kinase belonging to the AMP-activated protein kinase family. It is catalytically activated by phosphorylation via the upstream kinase LKB1. SIK1 is involved in multiple signal regulatory pathways, such as those related to glucose metabolism, inflammation, and cell growth regulation [3].

In a Kras-dependent lung cancer mouse model, conditional genetic loss of Sik1 led to increased tumor growth, which was further enhanced by loss of Sik3. This revealed that SIK1 and SIK3 mediate key tumor-suppressive effects of LKB1 in non-small cell lung cancer (NSCLC) [1]. In breast cancer, AKT-mediated phosphorylation of SIK1 compromises its tumor-suppressive functions, allowing breast cell tumorigenesis [2]. In colorectal cancer, SIK1 inhibits metastasis and chemoresistance through the TGF-β signaling pathway [4].

In conclusion, SIK1 plays a crucial role in tumor-suppression in various cancers, as demonstrated by gene knockout and conditional knockout mouse models. These models have provided insights into the functions of SIK1 in cancer-related biological processes, highlighting its potential as a therapeutic target in cancer treatment.