Abstract:
Colorectal cancer (CRC) has been referred to as the fourth most diagnosed cancer worldwide and the third leading cause of patient mortality in humans. Approximately, 1,931,590 new cases of CRC were reported with 935,137 patient deaths worldwide in 2020. CRC has become increasingly prevalent worldwide as well, with statistical trends indicated cancer-related deaths could reach as high as 71.5% by 2035. Currently, conventional treatments for CRC patients have fallen short as successful therapeutic strategies, due to lacking in patient response, severe side effects and modest specificity consequently resulting in patient mortality and/or tumour recurrence. The recent trend of immunotherapy in solid cancers such as melanoma have shown success with blocking antibodies including Nivolumab and Pembrolizumab. Siglecs are well known immunotherapeutic targets in cancer. Current checkpoint inhibitors have exhibited limited efficacy, prompting a need for novel therapeutics for targets such as Siglec-15. Presently, small molecule inhibitors targeting Siglec-15 are not explored alongside characterised regulatory mechanisms involving microRNAs in CRC progression. Therefore, a small molecule inhibitor to target Siglec-15 was elucidated in vitro and microRNA mediated inhibitor effects were investigated. Our research findings demonstrated that the SHG-8 molecule exerted significant cytotoxicity on cell viability, migration, and colony formation, with an IC50 value of approximately 20µM. SHG-8 significantly reduced the SIGLEC15 expression at the gene and protein levels. Notably, miR- 6715b-3p was the most upregulated miRNA in high-throughput sequencing, which was also validated via RT-qPCR. MiR-6715b-3p may regulate PTTG1IP, a potential oncogene which was validated via RT-qPCR and in silico analysis. Additionally, molecular docking studies revealed SHG-8 interactions with the Siglec-15 binding pocket with the binding affinity of - 5.4 kcal/mol, highlighting its role as a small molecule inhibitor. Importantly, Siglec-15 and PD-L1 are expressed on mutually exclusive cancer cell populations, suggesting the potential for combination therapies with PD-L1 antagonists.
Audience Take Away Notes:
- We synthesized an in-house beta-amino ketone compound (SHG8) that kills colorectal cancer cells with an IC50 of 20 µM
- This novel compound can inhibit the Siglec-15-Sia axis which is very important axis in cancer progression
- This is the first reported inhibitor of Siglec-15 and reduce proliferation, migration and colonization of cancer cells
- We performed the small RNA Seq (sRNA seq) to find the differential expressed miRNAs with SHG8 treatment
- MiR-6715b-3p was found be the highly upregulated miRNAs upon SHG8 treatment
