Extracellular signal-regulated protein kinase 1/2 (ERK1/2), the only known substrate of MEK1/2, is located downstream of the RAS-RAF-MEK-ERK (MAPK) pathway and is associated with the abnormal activation and poor prognosis of cancer. To date, several small-molecule inhibitors of RAS, RAF, and MEK have been reported to make rapid advances in cancer therapy; however, acquired resistance still occurs, thereby weakening the therapeutic efficacy of these inhibitors. Recently, selective inhibition of ERK1/2 has been regarded as a potential cancer therapeutic strategy that can not only effectively block the MAPK pathway but also overcome drug resistance caused by upstream mutations in RAS, RAF, and MEK. Herein, we summarize the oncogenic roles, key signaling network, and the single- and dual-target inhibitors of ERK1/2 in preclinical and clinical trials. Together, these inspiring findings shed new light on the discovery of more small-molecule inhibitors of ERK1/2 as candidate drugs to improve cancer therapeutics.

Hepatitis B virus (HBV) infection is a worldwide health problem, and chronic infection can cause many diseases ranging from liver fibrosis to hepatocellular carcinoma (HCC) by complicated mechanisms. Currently, the treatment of HBV infection mainly depends on interferons (IFNs) and nucleotide analogues (NAs); however, both have some limitations. In 2012, sodium taurocholate cotransporting polypeptide (NTCP) was identified as the entry receptor of HBV. Based upon this groundbreaking discovery, a series of molecules have been gradually developed and evaluated to discover novel entry inhibitors targeting NTCP. However, only two macromolecules have been used for potential clinical applications so far. In this Perspective, we focus on summarizing the structural features that convey the biological functions of NTCP, as well as further discuss the anti-HBV activity and selectivity of inhibitors in HBV-related diseases, which should provide clues in the future for the discovery of drug candidates targeting NTCP.

Colorectal cancer (CRC) is a common malignancy of the gastrointestinal tract, often accompanied by poor prognosis and high incidence and mortality. p21 activated kinases (PAKs) have been used as therapeutic targets because of their central role in many oncogenic signaling networks. By exploring tumor databases, we found that PAK1 overexpression is associated with poor prognosis in colorectal cancer, and therefore, PAK1‐targeted inhibition is a new potential therapeutic strategy for colorectal cancer. We identified that Balanol (compound 6, DB04098) can effectively target PAK1 by high‐throughput virtual screening. In vitro, compound 6 exhibited favorable PAK1 inhibition with potent anti‐proliferative and anti‐migration activity in SW480 cells. Additionally, we also found that compound 6 induced apoptosis and cytoprotective autophagy in SW480 cells. Together, these results indicate that compound 6 is a potential novel PAK1 inhibitor, which would be utilized as a candidate compound for future CRC treatment.

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