Polo-Like Kinase 1 Regulates Chromosomal Instability and Paclitaxel Resistance in Breast Cancer Cells

Structural regulation of PLK1 activity: implications for cell cycle function and drug discovery

Polo Like Kinase 1 (PLK1), a key regulator of mitosis whose overexpression is often associated with poor survival rates in cancer, continues to be widely investigated as an oncology drug target with clinical trials evaluating second and third generation inhibitors. In addition to the conserved N-terminal kinase domain (KD), a unique characteristic of the Polo-Like kinase family is the C-terminal polo-box domain (PBD). The PBD contains a phosphopeptide binding site that recognizes substrates primed by other kinases and furthermore is responsible for subcellular localization of PLK1 to specific sites in the nucleus including centrosomes and kinetochores. Another role of the PBD is its regulatory ability through domain-domain interactions with the KD to maintain an autoinhibited state of PLK1. Insights into post translational modifications and the PBD - KD domain-domain association have been obtained and show that key events in PLK1 regulation include phosphosubstrate binding, T210 phosphorylation and engagement with the Bora protein. These can induce an open and active conformation where the domain-domain inhibitory interactions no longer dominate. Further regulatory events recently described include the interchange between monomeric and dimeric forms, which can also serve to inhibit or activate PLK1 during the cell cycle. Different oligomeric forms of PLK1, existing as homodimers and heterodimers with PLK2, have been identified and likely play context dependent roles. This review provides an overview of recent information describing structural and mechanistic insights into inhibition of PLK1 and the temporal and spatial requirements of its activation and regulation. It also covers recent insights into the conformational regulation of other members of the Polo-Like kinase family. The implications of the conformational regulation of PLK1 with respect to cell cycle function and drug discovery are significant and are therefore discussed in detail.

Tumor-intrinsic CDC42BPB confers resistance to anti-PD-1 immune checkpoint blockade in breast cancer

Immune checkpoint blockade has been used to treat breast cancer, but the clinical responses remain relatively poor. We have used the CRISPR-Cas9 kinome knockout library consisting of 763 kinase genes to identify tumor-intrinsic kinases conferring resistance to anti-PD-1 immune checkpoint blockade. We have identified the CDC42BPB kinase as a potential target to overcome the resistance to anti-PD-1 immune checkpoint blockade immunotherapy. We found that CDC42BPB is highly expressed in breast cancer patients who are non-responsive to immunotherapy. Furthermore, a small-molecule pharmacological inhibitor, BDP5290, which targets CDC42BPB, synergized with anti-PD-1 and enhanced tumor cell killing by promoting T cell proliferation in both in vitro and in vivo assays. Moreover, anti-PD-1-resistant breast cancer cells showed higher expression of CDC42BPB, and its inhibition rendered the resistant cells more susceptible to T cell killing in the presence of anti-PD-1. We also found that CDC42BPB phosphorylated AURKA, which in turn upregulated PD-L1 through cMYC. Our results have revealed a robust link between tumor-intrinsic kinase and immunotherapy resistance and have provided a rationale for a unique combination therapy of CDC42BPB inhibition and anti-PD-1 immunotherapy for breast cancer.

BioKA: a curated and integrated biomarker knowledgebase for animals

Biomarkers play an important role in various area such as personalized medicine, drug development, clinical care, and molecule breeding. However, existing animals' biomarker resources predominantly focus on human diseases, leaving a significant gap in non-human animal disease understanding and breeding research. To address this limitation, we present BioKA (Biomarker Knowledgebase for Animals, https://ngdc.cncb.ac.cn/bioka), a curated and integrated knowledgebase encompassing multiple animal species, diseases/traits, and annotated resources. Currently, BioKA houses 16 296 biomarkers associated with 951 mapped diseases/traits across 31 species from 4747 references, including 11 925 gene/protein biomarkers, 1784 miRNA biomarkers, 1043 mutation biomarkers, 773 metabolic biomarkers, 357 circRNA biomarkers and 127 lncRNA biomarkers. Furthermore, BioKA integrates various annotations such as GOs, protein structures, protein-protein interaction networks, miRNA targets and so on, and constructs an interactive knowledge network of biomarkers including circRNA-miRNA-mRNA associations, lncRNA-miRNA associations and protein-protein associations, which is convenient for efficient data exploration. Moreover, BioKA provides detailed information on 308 breeds/strains of 13 species, and homologous annotations for 8784 biomarkers across 16 species, and offers three online application tools. The comprehensive knowledge provided by BioKA not only advances human disease research but also contributes to a deeper understanding of animal diseases and supports livestock breeding.

Site-specific delivery of cisplatin and paclitaxel mediated by liposomes: A promising approach in cancer chemotherapy

The site-specific delivery of drugs, especially anti-cancer drugs has been an interesting field for researchers and the reason is low accumulation of cytotoxic drugs in cancer cells. Although combination cancer therapy has been beneficial in providing cancer drug sensitivity, targeted delivery of drugs appears to be more efficient. One of the safe, biocompatible and efficient nano-scale delivery systems in anti-cancer drug delivery is liposomes. Their particle size is small and they have other properties such as adjustable physico-chemical properties, ease of functionalization and high entrapment efficiency. Cisplatin is a chemotherapy drug with clinical approval in patients, but its accumulation in cancer cells is low due to lack of targeted delivery and repeated administration results in resistance development. Gene and drug co-administration along with cisplatin/paclitaxel have resulted in increased sensitivity in tumor cells, but there is still space for more progress in cancer therapy. The delivery of cisplatin/paclitaxel by liposomes increases accumulation of drug in tumor cells and impairs activity of efflux pumps in promoting cytotoxicity. Moreover, phototherapy along with cisplatin/paclitaxel delivery can increase potential in tumor suppression. Smart nanoparticles including pH-sensitive nanoparticles provide site-specific delivery of cisplatin/paclitaxel. The functionalization of liposomes can be performed by ligands to increase targetability towards tumor cells in mediating site-specific delivery of cisplatin/paclitaxel. Finally, liposomes can mediate co-delivery of cisplatin/paclitaxel with drugs or genes in potentiating tumor suppression. Since drug resistance has caused therapy failure in cancer patients, and cisplatin/paclitaxel are among popular chemotherapy drugs, delivery of these drugs mediates targeted suppression of cancers and prevents development of drug resistance. Because of biocompatibility and safety of liposomes, they are currently used in clinical trials for treatment of cancer patients. In future, the optimal dose of using liposomes and optimal concentration of loading cisplatin/paclitaxel on liposomal nanocarriers in clinical trials should be determined.

Ten Years of CRISPRing Cancers In Vitro

Cell lines have always constituted a good investigation tool for cancer research, allowing scientists to understand the basic mechanisms underlying the complex network of phenomena peculiar to the transforming path from a healthy to cancerous cell. The introduction of CRISPR in everyday laboratory activity and its relative affordability greatly expanded the bench lab weaponry in the daily attempt to better understand tumor biology with the final aim to mitigate cancer's impact in our lives. In this review, we aim to report how this genome editing technique affected in the in vitro modeling of different aspects of tumor biology, its several declinations, and analyze the advantages and drawbacks of each of them.