Identification and evaluation of a novel PARP1 inhibitor for the treatment of triple-negative breast cancer

AXL inhibition prevents RPA2/CHK1-mediated homologous recombination to increase PARP inhibitor sensitivity in hepatocellular carcinoma

Homologous recombination defects (HRD) render cells fail to repair DNA double-strand break (DSB), which causes synthetic lethality in these cells with punch by poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi). Here, we reveal a receptor tyrosine kinase, AXL, whose inhibition leads to HRD in hepatocellular carcinoma (HCC) cells. AXL is upregulated in HCC tumors, which is positively correlated with low survival rates. AXL knockdown or AXL inhibition by bemcentinib reduces HR efficiency in HCC cells, and AXL plays its role in HR repair through its kinase activity. Furthermore, we find that AXL interacts with RPA2, enhancing the recruitment of RPA2 to DNA damage sites. Mechanistically, AXL promotes the tyrosinization of RPA2 at tyrosine 9, promoting the phosphorylation of CHK1, thereby strengthens the HR repair ability in HCC cells to resist DNA damage. In conclusion, our results reveal that AXL is a promising therapeutic biomarker for HCC patients, and present that targeting AXL-RPA2-CHK1 pathway together with PARP inhibitor will be effective therapeutic strategy in HCC.

Advances in Doxorubicin-based nano-drug delivery system in triple negative breast cancer

Triple positive breast cancer (TPBC) is one of the most aggressive breast cancer. Due to the unique cell phenotype, aggressiveness, metastatic potential and lack of receptors or targets, chemotherapy is the choice of treatment for TNBC. Doxorubicin (DOX), one of the representative agents of anthracycline chemotherapy, has better efficacy in patients with metastatic TNBC (mTNBC). DOX in anthracycline-based chemotherapy regimens have higher response rates. Nano-drug delivery systems possess unique targeting and ability of co-load, deliver and release chemotherapeutic drugs, active gene fragments and immune enhancing factors to effectively inhibit or kill tumor cells. Therefore, advances in nano-drug delivery systems for DOX therapy have attracted a considerable amount of attention from researchers. In this article, we have reviewed the progress of nano-drug delivery systems (e.g., Nanoparticles, Liposomes, Micelles, Nanogels, Dendrimers, Exosomes, etc.) applied to DOX in the treatment of TNBC. We also summarize the current progress of clinical trials of DOX combined with immune checkpoint inhibitors (ICIS) for the treatment of TNBC. The merits, demerits and future development of nanomedicine delivery systems in the treatment of TNBC are also envisioned, with the aim of providing a new class of safe and efficient thoughts for the treatment of TNBC.