Proteomic Mapping and Targeting of Mitotic Pericentriolar Material in Tumors Bearing Centrosome Amplification

PARP inhibitors suppress tumours via centrosome error-induced senescence independent of DNA damage response

BACKGROUND

Poly(ADP-ribose) polymerase (PARP) inhibitors have emerged as promising chemotherapeutic drugs primarily against BRCA1/2-associated tumours, known as synthetic lethality. However, recent clinical trials reported patients' survival benefits from PARP inhibitor treatments, irrelevant to homologous recombination deficiency. Therefore, revealing the therapeutic mechanism of PARP inhibitors beyond DNA damage repair is urgently needed, which can facilitate precision medicine.

METHODS

A CRISPR-based knock-in technology was used to establish stable BRCA1 mutant cancer cells. The effects of PARP inhibitors on BRCA1 mutant cancer cells were evaluated by biochemical and cell biological experiments. Finally, we validated its in vivo effects in xenograft and patient-derived xenograft (PDX) tumour mice.

FINDINGS

In this study, we uncovered that the majority of clinical BRCA1 mutations in breast cancers were in and near the middle of the gene, rather than in essential regions for DNA damage repair. Representative mutations such as R1085I and E1222Q caused transient extra spindle poles during mitosis in cancer cells. PAR, which is synthesized by PARP2 but not PARP1 at mitotic centrosomes, clustered these transient extra poles, independent of DNA damage response. Common PARP inhibitors could effectively suppress PARP2-synthesized PAR and induce cell senescence by abrogating the correction of mitotic extra-pole error.

INTERPRETATION

Our findings uncover an alternative mechanism by which PARP inhibitors efficiently suppress tumours, thereby pointing to a potential new therapeutic strategy for centrosome error-related tumours.

FUNDING

Funded by National Natural Science Foundation of China (NSFC) (T2225006, 82272948, 82103106), Beijing Municipal Natural Science Foundation (Key program Z220011), and the National Clinical Key Specialty Construction Program, P. R. China (2023).

Regulation of Cell Adhesion and Migration via Microtubule Cytoskeleton Organization, Cell Polarity, and Phosphoinositide Signaling

The capacity for cancer cells to metastasize to distant organs depends on their ability to execute the carefully choreographed processes of cell adhesion and migration. As most human cancers are of epithelial origin (carcinoma), the transcriptional downregulation of adherent/tight junction proteins (e.g., E-cadherin, Claudin and Occludin) with the concomitant gain of adhesive and migratory phenotypes has been extensively studied. Most research and reviews on cell adhesion and migration focus on the actin cytoskeleton and its reorganization. However, metastasizing cancer cells undergo the extensive reorganization of their cytoskeletal system, specifically in originating/nucleation sites of microtubules and their orientation (e.g., from non-centrosomal to centrosomal microtubule organizing centers). The precise mechanisms by which the spatial and temporal reorganization of microtubules are linked functionally with the acquisition of an adhesive and migratory phenotype as epithelial cells reversibly transition into mesenchymal cells during metastasis remains poorly understood. In this Special Issue of "Molecular Mechanisms Underlying Cell Adhesion and Migration", we highlight cell adhesion and migration from the perspectives of microtubule cytoskeletal reorganization, cell polarity and phosphoinositide signaling.

DNAJA2 deficiency activates cGAS-STING pathway via the induction of aberrant mitosis and chromosome instability

Molecular chaperone HSP70s are attractive targets for cancer therapy, but their substrate broadness and functional non-specificity have limited their role in therapeutical success. Functioning as HSP70's cochaperones, HSP40s determine the client specificity of HSP70s, and could be better targets for cancer therapy. Here we show that tumors defective in HSP40 member DNAJA2 are benefitted from immune-checkpoint blockade (ICB) therapy. Mechanistically, DNAJA2 maintains centrosome homeostasis by timely degrading key centriolar satellite proteins PCM1 and CEP290 via HSC70 chaperone-mediated autophagy (CMA). Tumor cells depleted of DNAJA2 or CMA factor LAMP2A exhibit elevated levels of centriolar satellite proteins, which causes aberrant mitosis characterized by abnormal spindles, chromosome missegregation and micronuclei formation. This activates the cGAS-STING pathway to enhance ICB therapy response in tumors derived from DNAJA2-deficient cells. Our study reveals a role for DNAJA2 to regulate mitotic division and chromosome stability and suggests DNAJA2 as a potential target to enhance cancer immunotherapy, thereby providing strategies to advance HSPs-based cancer therapy.

Intelligent nanomaterials for cancer therapy: recent progresses and future possibilities

Intelligent nanomedicine is currently one of the most active frontiers in cancer therapy development. Empowered by the recent progresses of nanobiotechnology, a new generation of multifunctional nanotherapeutics and imaging platforms has remarkably improved our capability to cope with the highly heterogeneous and complicated nature of cancer. With rationally designed multifunctionality and programmable assembly of functional subunits, the in vivo behaviors of intelligent nanosystems have become increasingly tunable, making them more efficient in performing sophisticated actions in physiological and pathological microenvironments. In recent years, intelligent nanomaterial-based theranostic platforms have showed great potential in tumor-targeted delivery, biological barrier circumvention, multi-responsive tumor sensing and drug release, as well as convergence with precise medication approaches such as personalized tumor vaccines. On the other hand, the increasing system complexity of anti-cancer nanomedicines also pose significant challenges in characterization, monitoring and clinical use, requesting a more comprehensive and dynamic understanding of nano-bio interactions. This review aims to briefly summarize the recent progresses achieved by intelligent nanomaterials in tumor-targeted drug delivery, tumor immunotherapy and temporospatially specific tumor imaging, as well as important advances of our knowledge on their interaction with biological systems. In the perspective of clinical translation, we have further discussed the major possibilities provided by disease-oriented development of anti-cancer nanomaterials, highlighting the critical importance clinically-oriented system design.

Identification of prognostic and therapeutic biomarkers in type 2 papillary renal cell carcinoma

BACKGROUND

Papillary renal cell carcinoma (PRCC) can be divided into type 1 (PRCC1) and type 2 (PRCC2) and PRCC2 share a more invasive phenotype and worse prognosis. This study aims to identify potential prognostic and therapeutic biomarkers in PRCC2.

METHODS

A cohort from The Cancer Genome Atlas and two datasets from Gene Expression Omnibus were examined. Common differentially expressed genes (DEGs) were screened and potential biomarkers were explored by using Kaplan-Meier method and cox regression analysis. Functional enrichment analysis was utilized to evaluate the potential biological functions. Tumor infiltrating immune cells were estimated by CIBERSORT algorithm. Ninety-two PRCC2 samples from Fudan University Shanghai Cancer Center were obtained, and immunostaining was performed to validate prognostic and therapeutic significance of the potential biomarker.

RESULTS

PRCC2 has worse overall survival and shares distinct molecular characteristics from PRCC1. There was significant higher expression level of Targeting protein for Xklp2 (TPX2) in PRCC2 compared with normal tissues. Higher expression level of TPX2 was significantly associated with worse overall survival in PRCC2 and kinesin family genes expression were found significantly elevated in high risk PRCC2. Abundance of tumor infiltrating M1 macrophage was significantly higher in PRCC2 and it was also associated with worse overall survival. In the FUSCC cohort, higher TPX2 expression was significantly correlated with worse overall and progression-free survival. Retrospective analysis indicated that mTOR inhibitor (everolimus) had greater efficacy in the high-risk group than in the low-risk group (overall response rate: 28.6% vs. 16.7%) and that everolimus had greater efficacy than sunitinib in the high-risk group (overall response rate: 28.6% vs. 20%).

CONCLUSIONS

TPX2 was a prognostic and therapeutic biomarker in PRCC2. Higher abundance of tumor infiltrating M1 macrophage was significantly associated with worse overall survival in PRCC2. mTOR inhibitors may have good efficacy in patients with high-risk PRCC2.

Whole-Genome Duplication and Genome Instability in Cancer Cells: Double the Trouble

Whole-genome duplication (WGD) is one of the most common genomic abnormalities in cancers. WGD can provide a source of redundant genes to buffer the deleterious effect of somatic alterations and facilitate clonal evolution in cancer cells. The extra DNA and centrosome burden after WGD is associated with an elevation of genome instability. Causes of genome instability are multifaceted and occur throughout the cell cycle. Among these are DNA damage caused by the abortive mitosis that initially triggers tetraploidization, replication stress and DNA damage associated with an enlarged genome, and chromosomal instability during the subsequent mitosis in the presence of extra centrosomes and altered spindle morphology. Here, we chronicle the events after WGD, from tetraploidization instigated by abortive mitosis including mitotic slippage and cytokinesis failure to the replication of the tetraploid genome, and finally, to the mitosis in the presence of supernumerary centrosomes. A recurring theme is the ability of some cancer cells to overcome the obstacles in place for preventing WGD. The underlying mechanisms range from the attenuation of the p53-dependent G₁ checkpoint to enabling pseudobipolar spindle formation via the clustering of supernumerary centrosomes. These survival tactics and the resulting genome instability confer a subset of polyploid cancer cells proliferative advantage over their diploid counterparts and the development of therapeutic resistance.