Diverse microtubule-targeted anticancer agents kill cells by inducing chromosome missegregation on multipolar spindles

CENP-E Inhibition Induces Chromosomal Instability and Synergizes with Diverse Microtubule-Targeting Agents in Breast Cancer

Drugs that perturb microtubules are commonly used to treat breast cancers of all subtypes in both early stage and metastatic disease, but they are effective in only approximately 50% of patients. High concentrations of microtubule-targeting agents can elicit mitotic arrest in cell culture models; however, recent evidence from primary and metastatic breast cancers has revealed that these agents only accumulate at intratumoral levels capable of inducing abnormal multipolar mitotic spindles, not mitotic arrest. Although the maintenance of multipolar spindles can generate cytotoxic rates of chromosomal instability (CIN), focusing of aberrant multipolar spindles into normal bipolar spindles can dramatically reduce CIN and confer resistance to microtubule poisons. Here, we showed that inhibition of the mitotic kinesin centromeric-associated protein-E (CENP-E) overcomes resistance caused by focusing multipolar spindles. Clinically relevant microtubule-targeting agents used a mechanistically conserved pathway to induce multipolar spindles without requiring centrosome amplification. Focusing could occur at any point in mitosis, with earlier focusing conferring greater resistance to antimicrotubule agents. CENP-E inhibition increased CIN on focused spindles by generating chromosomes that remained misaligned at spindle poles during anaphase, which substantially increased death in the resulting daughter cells. CENP-E inhibition synergized with diverse, clinically relevant microtubule poisons to potentiate cell death in cell lines and suppress tumor growth in orthotopic tumor models. These results suggest that primary resistance to microtubule-targeting drugs can be overcome by simultaneous inhibition of CENP-E. Significance: The increased incidence of polar chromosomes induced by inhibition of the mitotic kinesin CENP-E exacerbates chromosomal instability, reduces daughter cell viability, and improves sensitivity to microtubule-targeting therapies.

Paclitaxel in colon cancer management: from conventional chemotherapy to advanced nanocarrier delivery systems

Paclitaxel, a potent chemotherapeutic agent derived from the bark of the Pacific yew tree, has demonstrated significant efficacy in the treatment of various cancers, including colon cancer. This comprehensive review delves into the conventional treatments for colon cancer, emphasizing the crucial role of paclitaxel in contemporary management strategies. It explores the intricate process of sourcing and synthesizing paclitaxel, highlighting the importance of its structural properties in its anticancer activity. The review further elucidates the mechanism of action of paclitaxel, its pharmacological effects, and its integration into chemotherapy regimens for colon cancer. Additionally, novel drug delivery systems, such as nanocarriers, liposomes, nanoparticles, microspheres, micelles, microemulsions, and niosomes, are examined for their potential to enhance the therapeutic efficacy of paclitaxel. The discussion extends to recent clinical trials and patents, showcasing advancements in paclitaxel formulations aimed at improving treatment outcomes. The review concludes with prospects in the field underscoring the ongoing innovation and potential breakthroughs in colon cancer therapy.

YY2/BUB3 Axis promotes SAC Hyperactivation and Inhibits Colorectal Cancer Progression via Regulating Chromosomal Instability

Spindle assembly checkpoint (SAC) is a crucial safeguard mechanism of mitosis fidelity that ensures equal division of duplicated chromosomes to the two progeny cells. Impaired SAC can lead to chromosomal instability (CIN), a well-recognized hallmark of cancer that facilitates tumor progression; paradoxically, high CIN levels are associated with better therapeutic response and prognosis. However, the mechanism by which CIN determines tumor cell survival and therapeutic response remains poorly understood. Here, using a cross-omics approach, YY2 is identified as a mitotic regulator that promotes SAC activity by activating the transcription of budding uninhibited by benzimidazole 3 (BUB3), a component of SAC. While both conditions induce CIN, a defect in YY2/SAC activity enhances mitosis and tumor growth. Meanwhile, hyperactivation of SAC mediated by YY2/BUB3 triggers a delay in mitosis and suppresses growth. Furthermore, it is revealed that YY2/BUB3-mediated excessive CIN causes higher cell death rates and drug sensitivity, whereas residual tumor cells that survived DNA damage-based therapy have moderate CIN and increased drug resistance. These results provide insights into the role of SAC activity and CIN levels in influencing tumor cell survival and drug response, as well as suggest a novel anti-tumor therapeutic strategy that combines SAC activity modulators and DNA-damage agents.

Suppressing Anaphase-Promoting Complex/Cyclosome-Cell Division Cycle 20 Activity to Enhance the Effectiveness of Anti-Cancer Drugs That Induce Multipolar Mitotic Spindles

Paclitaxel induces multipolar spindles at clinically relevant doses but does not substantially increase mitotic indices. Paclitaxel's anti-cancer effects are hypothesized to occur by promoting chromosome mis-segregation on multipolar spindles leading to apoptosis, necrosis and cyclic-GMP-AMP Synthase-Stimulator of Interferon Genes (cGAS-STING) pathway activation in daughter cells, leading to secretion of type I interferon (IFN) and immunogenic cell death. Eribulin and vinorelbine have also been reported to cause increases in multipolar spindles in cancer cells. Recently, suppression of Anaphase-Promoting Complex/Cyclosome-Cell Division Cycle 20 (APC/C-CDC20) activity using CRISPR/Cas9 mutagenesis has been reported to increase sensitivity to Kinesin Family 18a (KIF18a) inhibition, which functions to suppress multipolar mitotic spindles in cancer cells. We propose that a way to enhance the effectiveness of anti-cancer agents that increase multipolar spindles is by suppressing the APC/C-CDC20 to delay, but not block, anaphase entry. Delaying anaphase entry in genomically unstable cells may enhance multipolar spindle-induced cell death. In genomically stable healthy human cells, delayed anaphase entry may suppress the level of multipolar spindles induced by anti-cancer drugs and lower mitotic cytotoxicity. We outline specific combinations of molecules to investigate that may achieve the goal of enhancing the effectiveness of anti-cancer agents.

The Causes and Consequences of DNA Damage and Chromosomal Instability Induced by Human Papillomavirus

High-risk human papillomaviruses (HPVs) are the main cause of cervical, oropharyngeal, and anogenital cancers, which are all treated with definitive chemoradiation therapy when locally advanced. HPV proteins are known to exploit the host DNA damage response to enable viral replication and the epithelial differentiation protocol. This has far-reaching consequences for the host genome, as the DNA damage response is critical for the maintenance of genomic stability. HPV+ cells therefore have increased DNA damage, leading to widespread genomic instability, a hallmark of cancer, which can contribute to tumorigenesis. Following transformation, high-risk HPV oncoproteins induce chromosomal instability, or chromosome missegregation during mitosis, which is associated with a further increase in DNA damage, particularly due to micronuclei and double-strand break formation. Thus, HPV induces significant DNA damage and activation of the DNA damage response in multiple contexts, which likely affects radiation sensitivity and efficacy. Here, we review how HPV activates the DNA damage response, how it induces chromosome missegregation and micronuclei formation, and discuss how these factors may affect radiation response. Understanding how HPV affects the DNA damage response in the context of radiation therapy may help determine potential mechanisms to improve therapeutic response.

Targeting chromosomal instability and aneuploidy in cancer

Cancer development and therapy resistance are driven by chromosomal instability (CIN), which causes chromosome gains and losses (i.e., aneuploidy) and structural chromosomal alterations. Technical limitations and knowledge gaps have delayed therapeutic targeting of CIN and aneuploidy in cancers. However, our toolbox for creating and studying aneuploidy in cell models has greatly expanded recently. Moreover, accumulating evidence suggests that seven conventional antimitotic chemotherapeutic drugs achieve clinical response by inducing CIN instead of mitotic arrest, although additional anticancer activities may also contribute in vivo. In this review, we discuss these recent developments. We also highlight new discoveries, which together show that 25 chromosome arm aneuploidies (CAAs) may be targetable by 36 drugs across 14 types of cancer. Collectively, these advances offer many new opportunities to improve cancer treatment.

Tanshinone IIA modulates cancer cell morphology and movement via Rho GTPases-mediated actin cytoskeleton remodeling

Actin filaments form unique structures with robust actin bundles and cytoskeletal networks affixed to the extracellular matrix and interact with neighboring cells, which are crucial structures for cancer cells to acquire a motile phenotype. This study aims to investigate a novel antitumor mechanism by which Tanshinone IIA (Tan IIA) modulates the morphology and migration of liver cancer cells via actin cytoskeleton regulation. 97H and Huh7 exhibited numerous tentacle-like protrusions that interacted with neighboring cells. Following treatment with Tan IIA, 97H and Huh7 showed a complete absence of cytoplasmic protrusion and adherens junctions, thereby effectively impeding their migration capability. The fluorescence staining of F-actin and microtubules indicated that these tentacle-like protrusions and cell-cell networks were actin-based structures that led to morphological changes after Tan IIA treatment by retracting and reorganizing beneath the membrane. Tan IIA can reverse the actin depolymerization and cell morphology alterations induced by latrunculin A. Tan IIA down-regulated actin and Rho GTPases expression significantly, as opposed to inducing Rho signaling activation. Preventing the activity of proteasomes and lysosomes had no discernible impact on the modifications in cellular structure and protein expression induced by Tan IIA. However, as demonstrated by the puromycin labeling technique, the newly synthesized proteins were significantly inhibited by Tan IIA. In conclusion, Tan IIA can induce dramatic actin cytoskeleton remodeling by inhibiting the protein synthesis of actin and Rho GTPases, resulting in the suppression of tumor growth and migration. Targeting the actin cytoskeleton of Tan IIA is a promising strategy for HCC treatment.