Navitoclax Enhances the Therapeutic Effects of PLK1 Targeting on Lung Cancer Cells in 2D and 3D Culture Systems

Injectable Senolytic Hydrogel Depot for the Clearance of Senescent Cells

Small molecules are frontline therapeutics for many diseases; however, they are often limited by their poor solubility. Therefore, hydrophobic small molecules are often encapsulated or prepared as pure drug nanoparticles. Navitoclax, used to eliminate senescent cells, is one such small molecule that faces challenges in translation due to its hydrophobicity and toxic side effects. Further, as senescent cells exhibit context-dependent pathologic or beneficial properties, it is preferable to eliminate senescent cells locally. To formulate navitoclax and enable local treatment, we designed an injectable hydrogel loaded with navitoclax nanoparticles as a senolytic delivery vehicle. Navitoclax nanoparticles (Ø ∼ 110 nm) were prepared via solvent-antisolvent nanoprecipitation and formulated in an injectable polymer-nanoparticle (PNP) hydrogel to create a local senolytic depot. Navitoclax-loaded PNP hydrogels selectively cleared senescent cells in vitro in senescent endothelial monolayers. This work demonstrates the value of formulating lipophilic small molecules and the potential of localized drug delivery strategies to improve senolytic therapies.

Onvansertib and Navitoclax Combination as a New Therapeutic Option for Mucinous Ovarian Carcinoma

Mucinous epithelial ovarian cancer (mEOC) is a rare subtype of epithelial ovarian cancer, characterized by poor responses to standard platinum-based chemotherapy. Polo-like kinase 1 (PLK1) is a key regulator of mitosis and cell cycle progression and its inhibition has been recently identified as a target in mEOC. In this study, we aimed to identify further therapeutic targets in mEOC using a CRISPR/Cas9 library targeting 3015 genes, with and without treatment with onvansertib, a PLK1 inhibitor. We identified twelve genes associated with cell survival (ZC2HC1C, RPA2, KIN17, TUBG1, SMC2, CDC26, CDC42, HOXA9, TAF10, SENP1, MRPS31, and COPS2) and three genes (JUND, CARD9, and BCL2L2) in synthetic lethality with onvansertib treatment. We validated that SENP1 downregulation is important for the growth of mEOC cells through esiRNA interference and the use of a pharmacological inhibitor Momordin Ic. The downregulation of CARD9 and BCL2L2 combined with subtoxic doses of onvansertib interfered with mEOC cell growth. Interestingly, the combination of navitoclax, an inhibitor of BcL2 family members including BCL2L2, was synergistic in all four of the mEOC cell lines tested and substantially induced cell death through apoptosis. These data support the use of a combination of navitoclax and onvansertib as a new therapeutic strategy for mEOC.

Time-Lapse Imaging to Analyze Cell Fate in Response to Antimitotics

Time-lapse imaging is a powerful technique widely used in Cellular and Molecular Biology to capture and analyze the dynamic processes of living cells over specific time periods. Particularly, in the study of cell division, under normal conditions or after drug treatments, this methodology can provide essential data that is impossible to obtain from conventional cell-fixed-based assays. In the context of evaluating cell fate after antimitotic drug treatment, time-lapse imaging provides valuable insights into the mechanisms of action of these compounds. Antimitotic drugs belong to a class of anticancer compounds that interfere with mitosis by targeting microtubules or specific kinases and molecular motors involved in the mitotic apparatus. This chapter aims to highlight the significant advantage of using time-lapse microscopy to assess the effects of antimitotic drugs on cell behavior and fates. We describe the full protocol for time-lapse imaging, using the human lung adenocarcinoma A549 cell line as a model, after exposure to the antimitotic BI2536, a potent inhibitor of polo-like kinase 1 (PLK1). This description includes software for imaging acquisition and data analysis.

Targeting treatment resistance in cervical cancer: A new avenue for senolytic therapies

Cervical cancer poses a significant global health challenge, particularly impacting women in economically developing nations. This disparity stems from a combination of factors, including inadequate screening infrastructure and resource limitations. However, the foremost contributor is the widespread lack of awareness and limited accessibility to Human Papillomavirus (HPV) vaccination, which is a key preventative measure against cervical cancer development. Despite advancements in cervical cancer prevention, treatment resistance remains a major hurdle in achieving improved patient outcomes. Cellular senescence, specifically the senescence-associated secretory phenotype (SASP) and its bidirectional relationship with the immune system, has been implicated in resistance to conventional cervical cancer chemotherapy treatments. The exact mechanisms by which this state of growth arrest and the associated changes in immune regulation contribute to cervical cancer progression and the associated drug resistance are not entirely understood. This underscores the necessity for innovative strategies to address the prevalence of treatment-resistant cervical cancer, with one promising avenue being the utilisation of senolytics. Senolytics are agents that have promising efficacy in clearing senescent cells from tumour tissues, however neither the utilisation of senolytics for addressing senescence-induced treatment resistance nor the potential integration of immunotherapy as senolytic agents in cervical cancer treatment has been explored to date. This review provides a concise overview of the mechanisms underlying senescence induction and the pivotal role of the immune system in this process. Additionally, it explores various senolytic approaches that hold significant potential for advancing cervical cancer research.

Coupling Kinesin Spindle Protein and Aurora B Inhibition with Apoptosis Induction Enhances Oral Cancer Cell Killing

Many proteins regulating mitosis have emerged as targets for cancer therapy, including the kinesin spindle protein (KSP) and Aurora kinase B (AurB). KSP is crucial for proper spindle pole separation during mitosis, while AurB plays roles in chromosome segregation and cytokinesis. Agents targeting KSP and AurB selectively affect dividing cells and have shown significant activity in vitro. However, these drugs, despite advancing to clinical trials, often yield unsatisfactory outcomes as monotherapy, likely due to variable responses driven by cyclin B degradation and apoptosis signal accumulation networks. Accumulated data suggest that combining emerging antimitotics with various cytostatic drugs can enhance tumor-killing effects compared to monotherapy. Here, we investigated the impact of inhibiting anti-apoptotic signals with the BH3-mimetic Navitoclax in oral cancer cells treated with the selective KSP inhibitor, Ispinesib, or AurB inhibitor, Barasertib, aiming to potentiate cell death. The combination of BH3-mimetics with both KSP and AurB inhibitors synergistically induced substantial cell death, primarily through apoptosis. A mechanistic analysis underlying this synergistic activity, undertaken by live-cell imaging, is presented. Our data underscore the importance of combining BH3-mimetics with antimitotics in clinical trials to maximize their effectiveness.

Maximizing Anticancer Response with MPS1 and CENPE Inhibition Alongside Apoptosis Induction

Antimitotic compounds, targeting key spindle assembly checkpoint (SAC) components (e.g., MPS1, Aurora kinase B, PLK1, KLP1, CENPE), are potential alternatives to microtubule-targeting antimitotic agents (e.g., paclitaxel) to circumvent resistance and side effects associated with their use. They can be classified into mitotic blockers, causing SAC-induced mitotic arrest, or mitotic drivers, pushing cells through aberrant mitosis by overriding SAC. These drugs, although advancing to clinical trials, exhibit unsatisfactory cancer treatment outcomes as monotherapy, probably due to variable cell fate responses driven by cyclin B degradation and apoptosis signal accumulation networks. We investigated the impact of inhibiting anti-apoptotic signals with the BH3-mimetic navitoclax in lung cancer cells treated with the selective CENPE inhibitor GSK923295 (mitotic blocker) or the MPS1 inhibitor BAY1217389 (mitotic driver). Our aim was to steer treated cancer cells towards cell death. BH3-mimetics, in combination with both mitotic blockers and drivers, induced substantial cell death, mainly through apoptosis, in 2D and 3D cultures. Crucially, these synergistic concentrations were less toxic to non-tumor cells. This highlights the significance of combining BH3-mimetics with antimitotics, either blockers or drivers, which have reached the clinical trial phase, to enhance their effectiveness.

Combination Therapy as a Promising Way to Fight Oral Cancer

Oral cancer is a highly aggressive tumor with invasive properties that can lead to metastasis and high mortality rates. Conventional treatment strategies, such as surgery, chemotherapy, and radiation therapy, alone or in combination, are associated with significant side effects. Currently, combination therapy has become the standard practice for the treatment of locally advanced oral cancer, emerging as an effective approach in improving outcomes. In this review, we present an in-depth analysis of the current advancements in combination therapies for oral cancer. The review explores the current therapeutic options and highlights the limitations of monotherapy approaches. It then focuses on combinatorial approaches that target microtubules, as well as various signaling pathway components implicated in oral cancer progression, namely, DNA repair players, the epidermal growth factor receptor, cyclin-dependent kinases, epigenetic readers, and immune checkpoint proteins. The review discusses the rationale behind combining different agents and examines the preclinical and clinical evidence supporting the effectiveness of these combinations, emphasizing their ability to enhance treatment response and overcome drug resistance. Challenges and limitations associated with combination therapy are discussed, including potential toxicity and the need for personalized treatment approaches. A future perspective is also provided to highlight the existing challenges and possible resolutions toward the clinical translation of current oral cancer therapies.

Novel Anticancer Strategies II

Owing to the exceptional complexity of the development and progression of cancer, diverse cancer types are alarmingly increasing worldwide [...].