Tetraploidy-linked sensitization to CENP-E inhibition in human cells

Targeting Kinesins for Therapeutic Exploitation of Chromosomal Instability in Lung Cancer

New therapeutic approaches that antagonize tumour-promoting phenotypes in lung cancer are needed to improve patient outcomes. Chromosomal instability (CIN) is a hallmark of lung cancer characterized by the ongoing acquisition of genetic alterations that include the gain and loss of whole chromosomes or segments of chromosomes as well as chromosomal rearrangements during cell division. Although it provides genetic diversity that fuels tumour evolution and enables the acquisition of aggressive phenotypes like immune evasion, metastasis, and drug resistance, too much CIN can be lethal because it creates genetic imbalances that disrupt essential genes and induce severe proteotoxic and metabolic stress. As such, sustaining advantageous levels of CIN that are compatible with survival is a fine balance in cancer cells, and potentiating CIN to levels that exceed a tolerable threshold is a promising treatment strategy for inherently unstable tumours like lung cancer. Kinesins are a superfamily of motor proteins with many members having functions in mitosis that are critical for the correct segregation of chromosomes and, consequently, maintaining genomic integrity. Accordingly, inhibition of such kinesins has been shown to exacerbate CIN. Therefore, inhibiting mitotic kinesins represents a promising strategy for amplifying CIN to lethal levels in vulnerable cancer cells. In this review, we describe the concept of CIN as a therapeutic vulnerability and comprehensively summarize studies reporting the clinical and functional relevance of kinesins in lung cancer, with the goal of outlining how kinesin inhibition, or "targeting kinesins", holds great potential as an effective strategy for treating lung cancer.

Kinetochore and ionomic adaptation to whole-genome duplication in Cochlearia shows evolutionary convergence in three autopolyploids

Whole-genome duplication (WGD) occurs in all kingdoms and impacts speciation, domestication, and cancer outcome. However, doubled DNA management can be challenging for nascent polyploids. The study of within-species polyploidy (autopolyploidy) permits focus on this DNA management aspect, decoupling it from the confounding effects of hybridization (in allopolyploid hybrids). How is autopolyploidy tolerated, and how do young polyploids stabilize? Here, we introduce a powerful model to address this: the genus Cochlearia, which has experienced many polyploidization events. We assess meiosis and other polyploid-relevant phenotypes, generate a chromosome-scale genome, and sequence 113 individuals from 33 ploidy-contrasting populations. We detect an obvious autopolyploidy-associated selection signal at kinetochore components and ion transporters. Modeling the selected alleles, we detail evidence of the kinetochore complex mediating adaptation to polyploidy. We compare candidates in independent autopolyploids across three genera separated by 40 million years, highlighting a common function at the process and gene levels, indicating evolutionary flexibility in response to polyploidy.

Tetraploidy as a metastable state towards malignant cell transformation within a systemic approach of cancer development

Tetraploidy, a condition in which a cell has four homologous sets of chromosomes, may be a natural physiological condition or pathophysiological such as in cancer cells or stress induced tetraploidisation. Its contribution to cancer development is well known. However, among the many models proposed to explain the causes, mechanisms and steps of malignant cell transformation, only few integrate tetraploidization into a systemic multistep approach of carcinogenesis. Therefore, we will i) describe the molecular and cellular characteristics of tetraploidy; ii) assess the contribution of stress-induced tetraploidy in cancer development; iii) situate tetraploidy as a metastable state leading to cancer development in a systemic cell-centered approach; iiii) consider knowledge gaps and future perspectives. The available data shows that stress-induced tetraploidisation/polyploidisation leads to p53 stabilisation, cell cycle arrest, followed by cellular senescence or apoptosis, suppressing the proliferation of tetraploid cells. However, if tetraploid cells escape the G1-tetraploidy checkpoint, it may lead to uncontrolled proliferation of tetraploid cells, micronuclei induction, aneuploidy and deploidisation. In addition, tetraploidization favors 3D-chromatin changes and epigenetic effects. The combined effects of genetic and epigenetic changes allow the expression of oncogenic gene expression and cancer progression. Moreover, since micronuclei are inducing inflammation, which in turn may induce additional tetraploidization, tetraploidy-derived genetic instability leads to a carcinogenic vicious cycle. The concept that polyploid cells are metastable intermediates between diploidy and aneuploidy is not new. Metastability denotes an intermediate energetic state within a dynamic system other than the system's state at least energy. Considering in parallel the genetic/epigenetic changes and the probable entropy levels induced by stress-induced tetraploidisation provides a new systemic approach to describe cancer development.

Kinesin-7 CENP-E in tumorigenesis: Chromosome instability, spindle assembly checkpoint, and applications

Kinesin motors are a large family of molecular motors that walk along microtubules to fulfill many roles in intracellular transport, microtubule organization, and chromosome alignment. Kinesin-7 CENP-E (Centromere protein E) is a chromosome scaffold-associated protein that is located in the corona layer of centromeres, which participates in kinetochore-microtubule attachment, chromosome alignment, and spindle assembly checkpoint. Over the past 3 decades, CENP-E has attracted great interest as a promising new mitotic target for cancer therapy and drug development. In this review, we describe expression patterns of CENP-E in multiple tumors and highlight the functions of CENP-E in cancer cell proliferation. We summarize recent advances in structural domains, roles, and functions of CENP-E in cell division. Notably, we describe the dual functions of CENP-E in inhibiting and promoting tumorigenesis. We summarize the mechanisms by which CENP-E affects tumorigenesis through chromosome instability and spindle assembly checkpoints. Finally, we overview and summarize the CENP-E-specific inhibitors, mechanisms of drug resistances and their applications.

Cell shape instability during cytokinesis in tetraploid HCT116 cells

Tetraploidy is a hallmark of broad cancer types, but it remains largely unknown which aspects of cellular processes are influenced by tetraploidization in human cells. Here, we found that tetraploid HCT116 cells manifested severe cell shape instability during cytokinesis, unlike their diploid counterparts. The cell shape instability accompanied the formation of protrusive deformation at the cell poles, indicating ectopic contractile activity of the cell cortex. While cytokinesis regulators such as RhoA and anillin correctly accumulated at the equatorial cortex, myosin II was over-accumulated at the cell poles, specifically in tetraploid cells. Suppression of myosin II activity by Y27632 treatment restored smooth cell shape in tetraploids during cytokinesis, indicating dysregulation of myosin II as a primary cause of the cell shape instability in the tetraploid state. Our results demonstrate a new aspect of the dynamic cellular process profoundly affected by tetraploidization in human cells, which provides a clue to molecular mechanisms of tetraploidy-driven pathogenic processes.