Cyclin-dependent kinase pathways as targets for cancer treatment

Tetrahydroisoquinolines - an updated patent review for cancer treatment (2016 - present)

INTRODUCTION

Cancer is a prominent cause of death globally, triggered by both non-genetic and genetic alterations in genes influenced by various environmental factors. The tetrahydroisoquinoline (THIQ), specifically 1,2,3,4-tetrahydroisoquinoline serves as fundamental element in various alkaloids, prevalent in proximity to quinoline and indole alkaloids.

AREA COVERED

In this review, the therapeutic applications of THIQ derivatives as an anticancer agent from 2016 to 2024 have been examined. The patents were gathered through comprehensive searches of the Espacenet, Google patent, WIPO, and Sci Finder databases. The therapeutic areas encompassed in the patents include numerous targets of cancer.

EXPERT OPINION

THIQ analogues play a crucial role in medicinal chemistry, with many being integral to pharmacological processes and clinical trials. Numerous THIQ compounds have been synthesized for therapeutic purposes, notably in cancer treatment. They show great promise for developing anticancer drugs, demonstrating strong affinity and efficacy against various cancer targets. The creation of multi-target ligands is a compelling avenue for THIQ-based anticancer drug discovery.

Exploiting spirooxindoles for dual DNA targeting/CDK2 inhibition and simultaneous mitigation of oxidative stress towards selective NSCLC therapy; synthesis, evaluation, and molecular modelling studies

The unique structure of spirooxindoles and their ability to feature various pharmacophoric motifs render them privileged scaffolds for tailoring new multitarget anticancer agents. Herein, a stereoselective multicomponent reaction was utilized to generate a small combinatorial library of pyrazole-tethered spirooxindoles targeting DNA and CDK2 with free radical scavenging potential as an extra bonus. The designed spirooxindoles were directed to combat NSCLC via inducing apoptosis and alleviating oxidative stress. The series' absolute configuration was assigned by X-ray diffraction analysis. Cytotoxicity screening of the developed spirooxindoles against NSCLC A549 and H460 cells compared to normal lung fibroblasts Wi-38 revealed the sensitivity of A549 cells to the compounds and raised 6e and 6h as the study hits (IC50 ∼ 0.09 μM and SI > 3). They damaged DNA at 24.6 and 35.3 nM, and surpassed roscovitine as CDK2 inhibitors (IC50 = 75.6 and 80.2 nM). Docking and MDs simulations postulated their receptors binding modes. The most potent derivative, 6e, induced A549 apoptosis by 40.85% arresting cell cycle at G2/M phase, and exhibited antioxidant activity in a dose-dependent manner compared to Trolox as indicated by DPPH scavenging assay. Finally, in silico ADMET analysis predicted the drug-likeness properties of 6e.

The role of palbociclib on the alterations in CDKN2, CCNE1, E2F3, MDM2 expressions as target genes of miR-141

INTRODUCTION

According to WHO, Breast cancer is widely considered to be the first or second cause of cancer-related death almost universally. Cell cycle disruption, either in the form of uncontrolled expression of cyclins or because of the suspension in negative regulatory proteins (CDK inhibitors), was found to cause breast cancer. Palbociclib as specific CDK4/6 inhibitor is used for the treatment of ER+ metastatic cancers. In this study, we are looking to investigate the effect of palbociclib on breast cancer cells and evaluate the changes in the expression of some genes involved in the cell cycle as target genes of miR-141 after treatment with this drug. We used MCF7 as functional estrogen and non-invasive and MDA-MB-231 cell lines as triple-negative type of breast cancer and a model for more aggressive.

METHOD & MATERIALS

MCF7 and MDA-MB-231 cell lines were cultured in DMEM medium. After counting cells and measuring viability, Palbociclib was administered at varying doses using the IC50 obtained from MTT, with the treatment given at two time points of 24 and 72 hours. RNA was extracted from untreated and treated cells and RNAs were converted to cDNA in the end. Gene expression changes were investigated by real-time PCR. Data management and analysis were conducted using GraphPad Prism 5.01 software.

RESULT AND CONCLUSION

Among investigated genes, E2F3 gene was not significantly affected by Palbociclib in any of cell lines and time points. Besides, the expression of CCNE1 gene was significantly suppressed. It seems this drug was unable to reduce the expression of MDM2 gene significantly in triple negative (MDA-MB-231) cancer cells; however, a decrease was observed in luminal A (MCF-7) cells. CDKN2A and miR-141 genes expression increased significantly after treatment which can be aligned with palbociclib in proliferation inhibition.

A Multi-Omics Analysis of an Exhausted T Cells' Molecular Signature in Pan-Cancer

T cells are essential tumor suppressors in cancer immunology, but their dysfunction induced by cancer cells can result in T cell exhaustion. Exhausted T cells (Tex) significantly influence the tumor immune environment, and thus, there is a need for their thorough investigation across different types of cancer. Here, we address the role of Tex cells in pan-cancer, focusing on the expression, mutations, methylation, immune infiltration, and drug sensitivity of a molecular signature comprising of the genes HAVCR2, CXCL13, LAG3, LAYN, TIGIT, and PDCD1across multiple cancer types, using bioinformatics analysis of TCGA data. Our analysis revealed that the Tex signature genes are differentially expressed across 14 cancer types, being correlated with patient survival outcomes, with distinct survival trends. Pathway analysis indicated that the Tex genes influence key cancer-related pathways, such as apoptosis, EMT, and DNA damage pathways. Immune infiltration analysis highlighted a positive correlation between Tex gene expression and immune cell infiltration in bladder cancer, while mutations in these genes were associated with specific immune cell enrichments in UCEC and SKCM. CNVs in Tex genes were widespread across cancers. We also highlight high LAYN methylation in most tumors and a negative correlation between methylation levels and immune cell infiltration in various cancers. Drug sensitivity analysis identified numerous correlations, with CXCL13 and HAVCR2 expressions influencing sensitivity to several drugs, including Apitolisib, Belinostat, and Docetaxel. Overall, these findings highlight the importance of reviving exhausted T cells to enhance the treatment efficacy to significantly boost anti-tumor immunity and achieve better clinical outcomes.

Discovery and preclinical evaluations of TQB3616, a novel CDK4-biased inhibitor

Among small-molecule CDK4/6 inhibitors (palbociclib, ribociclib, and abemaciclib) approved for metastatic breast cancers, abemaciclib has a more tolerable adverse effects in clinic. This is attributable to preferential inhibition of CDK4 over CDK6. In our search for a biased CDK4 inhibitor, we discovered a series of pyrimidine-indazole inhibitors. SAR studies led us to TQB3616 as a preferential CDK4 inhibitor. TQB3616 exhibited improvements in both enzymatic and cellular proliferation inhibitory potency when tested side-by-side with the FDA approved palbociclib and abemaciclib. TQB3616 also possessed favorable PK profile in multiple species. These differentiated properties, together with excellent GLP safety profile warranted TQB3616 moving to clinic. TQB3616 entered into clinical development in 2019 and currently in phase III clinical trials (NCT05375461, NCT05365178).

Inhibitors and PROTACs of CDK2: challenges and opportunities

INTRODUCTION

Abundant evidence suggests that the overexpression of CDK2-cyclin A/E complex disrupts normal cell cycle regulation, leading to uncontrolled proliferation of cancer cells. Thus, CDK2 has become a promising therapeutic target for cancer treatment. In recent years, insights into the structures of the CDK2 catalytic site and allosteric pockets have provided notable opportunities for developing more effective clinical candidates of CDK2 inhibitors.

AREA COVERED

This article reviews the latest CDK2 inhibitors that have entered clinical trials and discusses the design and discovery of the most promising new preclinical CDK2 inhibitors in recent years. Additionally, it summarizes the development of allosteric CDK2 inhibitors and CDK2-targeting PROTACs. The review encompasses strategies for inhibitor and PROTAC design, structure-activity relationships, as well as in vitro and in vivo biological assessments.

EXPERT OPINION

Despite considerable effort, no CDK2 inhibitor has yet received FDA approval for marketing due to poor selectivity and observed toxicity in clinical settings. Future research must prioritize the optimization of the selectivity, potency, and pharmacokinetics of CDK2 inhibitors and PROTACs. Moreover, exploring combination therapies incorporating CDK2 inhibitors with other targeted agents, or the design of multi-target inhibitors, presents significant promise for advancing cancer treatment strategies.

Synthetic Approaches and Clinical Application of Representative Small-Molecule Inhibitors of Cyclin-Dependent Kinase for Cancer Therapy

The regulation of the cancer cell cycle heavily relies on cyclin-dependent kinases (CDKs). Targeting CDKs has been identified as a promising approach for effective cancer therapy. In recent years, there has been significant attention paid towards developing small-molecule CDK inhibitors in the field of drug discovery. Notably, five such inhibitors have already received regulatory approval for the treatment of different cancers, including breast tumors, lung malignancies, and hematological malignancies. This review provides an overview of the synthetic routes used to produce 17 representative small-molecule CDK inhibitors that have obtained regulatory approval or are currently being evaluated through clinical trials. It also discusses their clinical applications for treating CDK-related diseases and explores the challenges and limitations associated with their use in a clinical setting, which will stimulate the further development of novel CDK inhibitors. By integrating therapeutic applications, synthetic methodologies, and mechanisms of action observed in various clinical trials involving these CDK inhibitors, this review facilitates a comprehensive understanding of the versatile roles and therapeutic potential offered by interventions targeting CDKs.

Cell cycle machinery in oncology: A comprehensive review of therapeutic targets

The cell cycle is tightly regulated to ensure controlled cell proliferation. Dysregulation of the cell cycle machinery is a hallmark of cancer that leads to unchecked growth. This review comprehensively analyzes key molecular regulators of the cell cycle and how they contribute to carcinogenesis when mutated or overexpressed. It focuses on cyclins, cyclin-dependent kinases (CDKs), CDK inhibitors, checkpoint kinases, and mitotic regulators as therapeutic targets. Promising strategies include CDK4/6 inhibitors like palbociclib, ribociclib, and abemaciclib for breast cancer treatment. Other possible targets include the anaphase-promoting complex/cyclosome (APC/C), Skp2, p21, and aurora kinase inhibitors. However, challenges with resistance have limited clinical successes so far. Future efforts should focus on combinatorial therapies, next-generation inhibitors, and biomarkers for patient selection. Targeting the cell cycle holds promise but further optimization is necessary to fully exploit it as an anti-cancer strategy across diverse malignancies.

Novel meriolin derivatives potently inhibit cell cycle progression and transcription in leukemia and lymphoma cells via inhibition of cyclin-dependent kinases (CDKs)

A key feature of cancer is the disruption of cell cycle regulation, which is characterized by the selective and abnormal activation of cyclin-dependent kinases (CDKs). Consequently, targeting CDKs via meriolins represents an attractive therapeutic approach for cancer therapy. Meriolins represent a semisynthetic compound class derived from meridianins and variolins with a known CDK inhibitory potential. Here, we analyzed the two novel derivatives meriolin 16 and meriolin 36 in comparison to other potent CDK inhibitors and could show that they displayed a high cytotoxic potential in different lymphoma and leukemia cell lines as well as in primary patient-derived lymphoma and leukemia cells. In a kinome screen, we showed that meriolin 16 and 36 prevalently inhibited most of the CDKs (such as CDK1, 2, 3, 5, 7, 8, 9, 12, 13, 16, 17, 18, 19, 20). In drug-to-target modeling studies, we predicted a common binding mode of meriolin 16 and 36 to the ATP-pocket of CDK2 and an additional flipped binding for meriolin 36. We could show that cell cycle progression and proliferation were blocked by abolishing phosphorylation of retinoblastoma protein (a major target of CDK2) at Ser612 and Thr82. Moreover, meriolin 16 prevented the CDK9-mediated phosphorylation of RNA polymerase II at Ser2 which is crucial for transcription initiation. This renders both meriolin derivatives as valuable anticancer drugs as they target three different Achilles' heels of the tumor: (1) inhibition of cell cycle progression and proliferation, (2) prevention of transcription, and (3) induction of cell death.

CDK7/CDK9 mediates transcriptional activation to prime paraptosis in cancer cells

BACKGROUND

Paraptosis is a programmed cell death characterized by cytoplasmic vacuolation, which has been explored as an alternative method for cancer treatment and is associated with cancer resistance. However, the mechanisms underlying the progression of paraptosis in cancer cells remain largely unknown.

METHODS

Paraptosis-inducing agents, CPYPP, cyclosporin A, and curcumin, were utilized to investigate the underlying mechanism of paraptosis. Next-generation sequencing and liquid chromatography-mass spectrometry analysis revealed significant changes in gene and protein expressions. Pharmacological and genetic approaches were employed to elucidate the transcriptional events related to paraptosis. Xenograft mouse models were employed to evaluate the potential of paraptosis as an anti-cancer strategy.

RESULTS

CPYPP, cyclosporin A, and curcumin induced cytoplasmic vacuolization and triggered paraptosis in cancer cells. The paraptotic program involved reactive oxygen species (ROS) provocation and the activation of proteostatic dynamics, leading to transcriptional activation associated with redox homeostasis and proteostasis. Both pharmacological and genetic approaches suggested that cyclin-dependent kinase (CDK) 7/9 drive paraptotic progression in a mutually-dependent manner with heat shock proteins (HSPs). Proteostatic stress, such as accumulated cysteine-thiols, HSPs, ubiquitin-proteasome system, endoplasmic reticulum stress, and unfolded protein response, as well as ROS provocation primarily within the nucleus, enforced CDK7/CDK9-Rpb1 (RNAPII subunit B1) activation by potentiating its interaction with HSPs and protein kinase R in a forward loop, amplifying transcriptional regulation and thereby exacerbating proteotoxicity leading to initiate paraptosis. The xenograft mouse models of MDA-MB-231 breast cancer and docetaxel-resistant OECM-1 head and neck cancer cells further confirmed the induction of paraptosis against tumor growth.

CONCLUSIONS

We propose a novel regulatory paradigm in which the activation of CDK7/CDK9-Rpb1 by nuclear proteostatic stress mediates transcriptional regulation to prime cancer cell paraptosis.

Single-cell and spatial transcriptomics reveal a high glycolysis B cell and tumor-associated macrophages cluster correlated with poor prognosis and exhausted immune microenvironment in diffuse large B-cell lymphoma

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous malignancy characterized by varied responses to treatment and prognoses. Understanding the metabolic characteristics driving DLBCL progression is crucial for developing personalized therapies.

METHODS

This study utilized multiple omics technologies including single-cell transcriptomics (n = 5), bulk transcriptomics (n = 966), spatial transcriptomics (n = 10), immunohistochemistry (n = 34), multiple immunofluorescence (n = 20) and to elucidate the metabolic features of highly malignant DLBCL cells and tumor-associated macrophages (TAMs), along with their associated tumor microenvironment. Metabolic pathway analysis facilitated by scMetabolism, and integrated analysis via hdWGCNA, identified glycolysis genes correlating with malignancy, and the prognostic value of glycolysis genes (STMN1, ENO1, PKM, and CDK1) and TAMs were verified.

RESULTS

High-glycolysis malignant DLBCL tissues exhibited an immunosuppressive microenvironment characterized by abundant IFN_TAMs (CD68+CXCL10+PD-L1+) and diminished CD8+ T cell infiltration. Glycolysis genes were positively correlated with malignancy degree. IFN_TAMs exhibited high glycolysis activity and closely communicating with high-malignancy DLBCL cells identified within datasets. The glycolysis score, evaluated by seven genes, emerged as an independent prognostic factor (HR = 1.796, 95% CI: 1.077-2.995, p = 0.025 and HR = 2.631, 95% CI: 1.207-5.735, p = 0.015) along with IFN_TAMs were positively correlated with poor survival (p < 0.05) in DLBCL. Immunohistochemical validation of glycolysis markers (STMN1, ENO1, PKM, and CDK1) and multiple immunofluorescence validation of IFN_TAMs underscored their prognostic value (p < 0.05) in DLBCL.

CONCLUSIONS

This study underscores the significance of glycolysis in tumor progression and modulation of the immune microenvironment. The identified glycolysis genes and IFN_TAMs represent potential prognostic markers and therapeutic targets in DLBCL.

Structure-independent machine-learning predictions of the CDK12 interactome

Cyclin-dependent kinase 12 (CDK12) is a critical regulatory protein involved in transcription and DNA repair processes. Dysregulation of CDK12 has been implicated in various diseases, including cancer. Understanding the CDK12 interactome is pivotal for elucidating its functional roles and potential therapeutic targets. Traditional methods for interactome prediction often rely on protein structure information, limiting applicability to CDK12 characterized by partly disordered terminal C region. In this study, we present a structure-independent machine-learning model that utilizes proteins' sequence and functional data to predict the CDK12 interactome. This approach is motivated by the disordered character of the CDK12 C-terminal region mitigating a structure-driven search for binding partners. Our approach incorporates multiple data sources, including protein-protein interaction networks, functional annotations, and sequence-based features, to construct a comprehensive CDK12 interactome prediction model. The ability to predict CDK12 interactions without relying on structural information is a significant advancement, as many potential interaction partners may lack crystallographic data. In conclusion, our structure-independent machine-learning model presents a powerful tool for predicting the CDK12 interactome and holds promise in advancing our understanding of CDK12 biology, identifying potential therapeutic targets, and facilitating precision-medicine approaches for CDK12-associated diseases.

Current Systemic Therapy in Men with Metastatic Castration-Sensitive Prostate Cancer

PURPOSE OF REVIEW

This review aims to explore the evolving landscape of treatments available for metastatic castration-sensitive prostate cancer (mCSPC) patients.

RECENT FINDINGS

In less than a decade, evidence was chronologically provided that (1) systemic treatment intensification with docetaxel improves outcomes, including survival, in men with mCSPC, (2) then that these outcomes are also improved when a second-generation androgen receptor pathway inhibitor (ARPI) is combined with androgen deprivation therapy (ADT), and (3) using a "triplet systemic therapy," which consists in the combination of ADT, an ARPI and docetaxel, further improves outcomes, including survival. Radiotherapy to the prostate combined with ADT alone is now recommended in men with low-volume mCSPC. Combining prostate radiotherapy and intensified systemic treatment including abiraterone may be synergistic as suggested in the PEACE-1 trial. Also, the role of metastases-directed local therapies (mostly stereotactic radiotherapy) is currently being assessed in phase 3 trials. Finally, the integration of biomarkers (e.g. BRCA2 gene alterations, PTEN loss, PSMA expression) for decision making is not currently established, though trials are also currently underway. Importantly, most evidence currently available was obtained in men with de novo metastases, while for those with metastatic relapse after definitive local treatment, the role of treatment intensification is less well established. Treatment intensification is nowadays the standard of care for patients with de novo mCSPC as it leads to outcomes improvement, including survival, and the standard of care is evolving almost on a yearly basis.

O-GlcNAcylation of E3 ubiquitin ligase SKP2 promotes hepatocellular carcinoma proliferation

O-linked-β-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) and ubiquitination are critical posttranslational modifications that regulate tumor development and progression. The continuous progression of the cell cycle is the fundamental cause of tumor proliferation. S-phase kinase-associated protein 2 (SKP2), an important E3 ubiquitin ligase, assumes a pivotal function in the regulation of the cell cycle. However, it is still unclear whether SKP2 is an effector of O-GlcNAcylation that affects tumor progression. In this study, we found that SKP2 interacted with O-GlcNAc transferase (OGT) and was highly O-GlcNAcylated in hepatocellular carcinoma (HCC). Mechanistically, the O-GlcNAcylation at Ser34 stabilized SKP2 by reducing its ubiquitination and degradation mediated by APC-CDH1. Moreover, the O-GlcNAcylation of SKP2 enhanced its binding ability with SKP1, thereby enhancing its ubiquitin ligase function. Consequently, SKP2 facilitated the transition from the G1-S phase of the cell cycle by promoting the ubiquitin degradation of cell cycle-dependent kinase inhibitors p27 and p21. Additionally, targeting the O-GlcNAcylation of SKP2 significantly suppressed the proliferation of HCC. Altogether, our findings reveal that O-GlcNAcylation, a novel posttranslational modification of SKP2, plays a crucial role in promoting HCC proliferation, and targeting the O-GlcNAcylation of SKP2 may become a new therapeutic strategy to impede the progression of HCC.

Kinase inhibitor macrocycles: a perspective on limiting conformational flexibility when targeting the kinome with small molecules

Methods utilized for drug discovery and development within the kinome have rapidly evolved since the approval of imatinib, the first small molecule kinase inhibitor. Macrocycles have received increasing interest as a technique to improve kinase inhibitor drug properties evident by the FDA approvals of lorlatinib, pacritinib, and repotrectinib. Compared to their acyclic counterparts, macrocycles can possess improved pharmacodynamic and pharmacokinetic properties. This review highlights clinical success stories when implementing macrocycles in kinase-based drug discovery and showcases that macrocyclization is a clinically validated drug discovery strategy when targeting the kinome.

Middle Eastern Plants with Potent Cytotoxic Effect Against Lung Cancer Cells

Cancer is one of the leading causes of increasing global mortality with uprising health concerns and threats. Unfortunately, conventional chemotherapy has substantial side effects, limiting its relevance and prompting a quest for safe and efficient alternatives. For thousands of years, plants have provided a rich reservoir for curing a variety of ailments, including cancer. According to the World Health Organization, medicinal plants would be the best source of medications. However, only 25% of drugs in the present pharmacopoeia are derived from plants. Hence, further research into different plants is required to better understand their efficacy. Twenty extracts of widely distributed Middle Eastern plants were screened for the cytotoxic effect against lung cancer cell lines (A549). Eleven plants showed IC50 below 25 μg/mL, consequently, the bioactive extracts were further fractionated by graded precipitation using absolute ethanol. All fraction A (FA; crude polysaccharides precipitate) showed potent IC50, 0.2-5.5 μg/mL except the FA of Brassica juncea, Silybum marianum, and Phaseolus vulgaris, whereas FB fractions (filtrate) of Anastatica hierochuntica, Plantago ovate, Tussilago farfara, and Cucurbita moschata had lower efficacy than other fractions with IC50 values in the range of 0.1-7.7 μg/mL. The fractions of FA Taraxacum officinale and FB Ziziphus spina possess the most potent cytotoxic activity with IC50, 0.2 and 0.1 μg/mL, respectively. Moreover, cell cycle analysis of both fractions revealed an arrest at G1/S-phase and activation of apoptosis rather than necrosis as the mode of cell death. Therefore, T. officinale and Z. spina fractions may pave the way to manage lung carcinoma as an alternative and complementary food regimen.

Neosetophomone B induces apoptosis in multiple myeloma cells via targeting of AKT/SKP2 signaling pathway

Multiple myeloma (MM) is a hematologic malignancy associated with malignant plasma cell proliferation in the bone marrow. Despite the available treatments, drug resistance and adverse side effects pose significant challenges, underscoring the need for alternative therapeutic strategies. Natural products, like the fungal metabolite neosetophomone B (NSP-B), have emerged as potential therapeutic agents due to their bioactive properties. Our study investigated NSP-B's antitumor effects on MM cell lines (U266 and RPMI8226) and the involved molecular mechanisms. NSP-B demonstrated significant growth inhibition and apoptotic induction, triggered by reduced AKT activation and downregulation of the inhibitors of apoptotic proteins and S-phase kinase protein. This was accompanied by an upregulation of p21Kip1 and p27Cip1 and an elevated Bax/BCL2 ratio, culminating in caspase-dependent apoptosis. Interestingly, NSP-B also enhanced the cytotoxicity of bortezomib (BTZ), an existing MM treatment. Overall, our findings demonstrated that NSP-B induces caspase-dependent apoptosis, increases cell damage, and suppresses MM cell proliferation while improving the cytotoxic impact of BTZ. These findings suggest that NSP-B can be used alone or in combination with other medicines to treat MM, highlighting its importance as a promising phytoconstituent in cancer therapy.

SNRPB promotes the progression of hepatocellular carcinoma via regulating cell cycle, oxidative stress, and ferroptosis

Small Nuclear Ribonucleoprotein Polypeptides B and B1 (SNRPB) have been linked to multiple human cancers. However, the mechanism of SNRPB in hepatocellular carcinoma (HCC) and whether SNRPB has a synergistic effect with sorafenib in the treatment of HCC remain unclear. In this study, bioinformatic analysis found that SNRPB was an independent prognostic factor for HCC that exerted a critical effect on the progression of HCC. SNRPB was linked with immune checkpoints, cell cycle, oxidative stress and ferroptosis in HCC. Single cell sequencing analysis found that HCC cell subset with high expression of SNRPB, accounted for a higher proportion in HCC cells with higher stages, had higher expression levels of the genes which promote cell cycle, inhibit oxidative stress and ferroptosis, and had higher cell cycle score, lower oxidative stress score and ferroptosis score. Single-sample gene set enrichment analysis (ssGSEA) analysis found that 17 oxidative stress pathways and 68 oxidative stress-ferroptosis related genes were significantly correlated with SNRPB risk scores. SNRPB knockdown induced cell cycle G2/M arrest and restrained cell proliferation, while downregulated the expression of CDK1, CDK4, and CyclinB1. The combined treatment (SNRPB knockdown+sorafenib) significantly inhibited tumor growth. In addition, the expression of SLC7A11, which is closely-related to ferroptosis, decreased significantly in vitro and in vivo. Therefore, SNRPB may promote HCC progression by regulating immune checkpoints, cell cycle, oxidative stress and ferroptosis, while its downregulation inhibits cell proliferation, which enhances the therapeutic effect of sorafenib, providing a novel basis for the development of HCC therapies.

Chondroitin Sulphate: An emerging therapeutic multidimensional proteoglycan in colon cancer

Chondroitin sulfate (CS) is a sulfated glycosaminoglycan (GAG) that has captured massive attention in the field of drug delivery. As the colon is considered the preferred site for local and systemic delivery of bioactive agents for the treatment of various diseases, colon-targeted drug delivery rose to the surface of research. Amid several tactics to attain colon-targeted drug release, the exploitation of polymers degraded by colonic bacteria holds great promise. Chondroitin sulfate as a biodegradable, biocompatible mucopolysaccharide is known for its anti-inflammatory, anti-osteoarthritis, anti-atherosclerotic, anti-oxidant, and anti-coagulant effects. Besides these therapeutic functions, CS thrived to play a major role in nanocarriers as a matrix material, coat, and targeting ligand. This review focuses on the role of CS in nanocarriers as a matrix material or as a targeting moiety for colon cancer therapy, relating the present applications to future perspectives.

Peripheral blood lymphocytes predict clinical outcomes in hormone receptor-positive HER2-negative advanced breast cancer patients treated with CDK4/6 inhibitors

Background

Cyclin-Dependent Kinase 4/6 inhibitors (CDK4/6i) combined with Endocrine Therapy (ET) are the standard treatment for patients with Hormone Receptor-positive/HER2-negative advanced breast cancer (HR+/HER2- aBC).

Objectives

While CDK4/6i are known to reduce several peripheral blood cells, such as neutrophils, lymphocytes and platelets, the impact of these modulations on clinical outcomes is unknown.

Design

A multicenter, retrospective-prospective Italian study.

Methods

We investigated the association between baseline peripheral blood cells, or their early modifications (i.e. 2 weeks after treatment initiation), and the progression-free survival (PFS) of HR+/HER2- aBC patients treated with ETs plus CDK4/6i. Random Forest models were used to select covariates associated with patient PFS among a large list of patient- and tumor-related variables.

Results

We evaluated 638 HR+/HER2- aBC patients treated with ET plus CDK4/6i at six Italian Institutions between January 2017 and May 2021. High baseline lymphocyte counts were independently associated with longer PFS [median PFS (mPFS) 20.1 versus 13.2 months in high versus low lymphocyte patients, respectively; adjusted Hazard Ratio (aHR): 0.78; 95% confidence interval (CI): 0.66-0.92; p = 0.0144]. Moreover, patients experiencing a lower early reduction of lymphocyte counts had significantly longer PFS when compared to patients undergoing higher lymphocyte decrease (mPFS 18.1 versus 14.5 months; aHR: 0.82; 95% CI: 0.73-0.93; p = 0.0037). Patients with high baseline lymphocytes and undergoing a lower reduction, or even an increase, of lymphocyte counts during CDK4/6i therapy experienced the longest PFS, while patients with lower baseline lymphocytes and undergoing a higher decrease of lymphocytes had the lowest PFS (mPFS 21.4 versus 11 months, respectively).

Conclusion

Baseline and on-treatment modifications of peripheral blood lymphocytes have independent prognostic value in HR+/HER2- aBC patients. This study supports the implementation of clinical strategies to boost antitumor immunity in patients with HR+/HER2- aBC treated with ETs plus CDK4/6i.

Thiazolo-pyridopyrimidines: An in silico evaluation as a lead for CDK4/6 inhibition, synthesis and cytotoxicity screening against breast cancer cell lines

Introduction

Pyridopyrimidines belong to a class of compounds characterized by the presence of nitrogen as heteroatoms. These compounds exhibit diverse biological effects, particularly showing promise as anticancer agents, including actions that inhibit CDK4/6.

Methods

We designed and synthesized a range of substituted thiazolo-pyridopyrimidines (4a-p). Computational ADME/T analysis and molecular docking were performed using the crystal structure of CDK4/6. Subsequently, we synthesized the top-scoring compounds, characterized them using IR, NMR, and Mass spectroscopy, and assessed their impact on MCF-7 and MDAMB-231 cell lines using the SRB assay. To further evaluate stability, molecular dynamics simulations were conducted for the two most promising compounds within the binding site.

Results

The docking scores indicated stronger interactions for compounds 4a, 4c, 4d, and 4g. As a result, these specific compounds (4a, 4c, 4d, and 4g) were chosen for synthesis and subsequent screening to assess their cytotoxic effects. Remarkably, compounds 4c and 4a exhibited the most promising activity in terms of their IC50 values across both tested cell lines. Furthermore, molecular dynamics simulation studies uncovered an elevated level of stability within the 4c-6OQO complex.

Conclusion

By integrating insights from computational, in vitro, and molecular dynamics simulation findings, compound 4c emerges as a leading candidate for future investigations. The presence of a polar hydroxyl group at the C2 position of the 8-phenyl substitution on the pyridopyrimidine rings appears to contribute to the heightened activity of the compound. Further enhancements to cytotoxic potential could be achieved through structural refinements.

Exploring the therapeutic potential of ADC combination for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer. Currently, standard treatment options for TNBC are limited to surgery, adjuvant chemotherapy, and radiotherapy. However, these treatment methods are associated with a higher risk of intrinsic or acquired recurrence. Antibody-drug conjugates (ADCs) have emerged as a useful and promising class of cancer therapeutics. ADCs, also known as "biochemical missiles", use a monoclonal antibody (mAb) to target tumor antigens and deliver a cytotoxic drug payload. Currently, several ADCs clinical studies are underway worldwide, including sacituzumab govitecan (SG), which was recently approved by the FDA for the treatment of TNBC. However, due to the fact that only a small portion of TNBC patients respond to ADC therapy and often develop resistance, growing evidence supports the use of ADCs in combination with other treatment strategies to treat TNBC. In this review, we described the current utilization of ADCs and discussed the prospects of ADC combination therapy for TNBC.

Insulin-like Growth Factor II mRNA-Binding Protein 1 Regulates Pancreatic Cancer Cell Growth through the Surveillance of CDC25A mRNA

A number of data indicate that the sources of different kinds of PDAC may be discovered at the transcription/transduction stage. RNA metabolism is manipulated at various steps by different RNA-binding proteins (RBPs), and the deregulation or irregular activity of RBPs is known to contribute to tumor promotion and progression. The insulin-like growth factor 2 mRNA-binding protein family (IMPs), and IMP1 in particular, has been linked with a poor prognosis in PDAC patients; however, little is known about its contribution in PDAC carcinogenesis. In this study, we investigated the function of IMP1 in PDAC. To evaluate IMP1 expression and correlation with PDAC prognosis, we utilized several public databases. Using a specific siRNA IMP1, we analyzed cell death and cell cycle progression in PDAC cell lines and 3D spheroids. The role of IMP1 was also evaluated in vivo in a Panc-1-derived tumor xenograft murine model. Public data suggest that PDAC patients with higher expression of IMP1 showed poor overall and progression-free survival. IMP1 silencing leads to reduced cell growth in PDAC cells and three-dimensional spheroids. Abrogation of IMP1 in PDAC cells showed lower levels of CDC25A, increased phosphorylation of the cyclin-dependent kinase (CDK)2, and accumulation of PDAC cells in the G1 phase. Immunoprecipitation experiments revealed that IMP1 binds CDC25A mRNA, thus controlling cell-cycle progression. Ultimately, we proved that suppression of IMP1 blocked in vivo growth of Panc-1 transferred into immunodeficient mice. Our results indicate that IMP1 drives the PDCA cell cycle and represents a novel strategy for overcoming PDCA cell proliferation.

Repositioning of simvastatin for diabetic colon cancer: role of CDK4 inhibition and apoptosis

There is increased risk of colon cancer in both men and women having diabetes. The objective of the study was to evaluate the role of simvastatin in colon cancer associated with type 2 diabetes mellitus. Diabetes was induced by administering high fat diet with low dose streptozotocin model. 1,2 dimethylhydrazine (25 mg/kg, sc) was used for colon cancer induction. MTT assay, scratch assay, clonogenic assay and annexin V-FITC assay using flow cytometry were performed on HCT-15 cell line. Simvastatin controlled diabetes and colon cancer in animal models and reduced mRNA expression of CDK4 in colon tissues. In vitro studies revealed that simvastatin showed a decrease in cell viability and produced dose dependent decrease in clone formation. There was decrease in the rate of migration with increase in concentration of simvastatin in scratch assay. Moreover, simvastatin induced apoptosis as depicted from annexin V-FITC assay using flow cytometry as well as that revealed by tunnel assay. Our data suggest that simvastatin exhibits protective role in colon cancer associated with diabetes mellitus and acts possibly via down regulation of CDK4 and induction of apoptosis and hence can be considered for repositioning in diabetic colon cancer.

A molecular landscape of quiescence and proliferation highlights the role of Pten in mammary gland acinogenesis

Cell context is key for cell state. Using physiologically relevant models of laminin-rich extracellular matrix (lrECM) induction of mammary epithelial cell quiescence and differentiation, we provide a landscape of the key molecules for the proliferation-quiescence decision, identifying multiple layers of regulation at the mRNA and protein levels. Quiescence occurred despite activity of Fak (also known as PTK2), Src and phosphoinositide 3-kinases (PI3Ks), suggesting the existence of a disconnecting node between upstream and downstream proliferative signalling. Pten, a lipid and protein phosphatase, fulfils this role, because its inhibition increased proliferation and restored signalling via the Akt, mTORC1, mTORC2 and mitogen-activated protein kinase (MAPK) pathways. Pten and laminin levels were positively correlated in developing murine mammary epithelia, and Pten localized apicolaterally in luminal cells in ducts and near the nascent lumen in terminal end buds. Consistently, in three-dimensional acinogenesis models, Pten was required for triggering and sustaining quiescence, polarity and architecture. The multilayered regulatory circuitry that we uncovered provides an explanation for the robustness of quiescence within a growth-suppressive microenvironment, which could nonetheless be disrupted by perturbations in master regulators such as Pten.

Limited clinical activity of palbociclib and ribociclib monotherapy in advanced cancers with cyclin D-CDK4/6 pathway alterations in the Dutch DRUP and Australian MoST trials

The Dutch Drug Rediscovery Protocol (DRUP) and the Australian Cancer Molecular Screening and Therapeutic (MoST) Program are similar nonrandomized, multidrug, pan-cancer trial platforms that aim to identify signals of clinical activity of molecularly matched targeted therapies or immunotherapies outside their approved indications. Here, we report results for advanced or metastatic cancer patients with tumors harboring cyclin D-CDK4/6 pathway alterations treated with CDK4/6 inhibitors palbociclib or ribociclib. We included adult patients that had therapy-refractory solid malignancies with the following alterations: amplifications of CDK4, CDK6, CCND1, CCND2 or CCND3, or complete loss of CDKN2A or SMARCA4. Within MoST, all patients were treated with palbociclib, whereas in DRUP, palbociclib and ribociclib were assigned to different cohorts (defined by tumor type and alteration). The primary endpoint for this combined analysis was clinical benefit, defined as confirmed objective response or stable disease ≥16 weeks. We treated 139 patients with a broad variety of tumor types; 116 with palbociclib and 23 with ribociclib. In 112 evaluable patients, the objective response rate was 0% and clinical benefit rate at 16 weeks was 15%. Median progression-free survival was 4 months (95% CI: 3-5 months), and median overall survival 5 months (95% CI: 4-6 months). In conclusion, only limited clinical activity of palbociclib and ribociclib monotherapy in patients with pretreated cancers harboring cyclin D-CDK4/6 pathway alterations was observed. Our findings indicate that monotherapy use of palbociclib or ribociclib is not recommended and that merging data of two similar precision oncology trials is feasible.

Cyclin-dependent kinases: Masters of the eukaryotic universe

A family of structurally related cyclin-dependent protein kinases (CDKs) drives many aspects of eukaryotic cell function. Much of the literature in this area has considered individual members of this family to act primarily either as regulators of the cell cycle, the context in which CDKs were first discovered, or as regulators of transcription. Until recently, CDK7 was the only clear example of a CDK that functions in both processes. However, new data points to several "cell-cycle" CDKs having important roles in transcription and some "transcriptional" CDKs having cell cycle-related targets. For example, novel functions in transcription have been demonstrated for the archetypal cell cycle regulator CDK1. The increasing evidence of the overlap between these two CDK types suggests that they might play a critical role in coordinating the two processes. Here we review the canonical functions of cell-cycle and transcriptional CDKs, and provide an update on how these kinases collaborate to perform important cellular functions. We also provide a brief overview of how dysregulation of CDKs contributes to carcinogenesis, and possible treatment avenues. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Processing > 3' End Processing RNA Processing > Splicing Regulation/Alternative Splicing.

The Therapeutic Potential of CDK4/6 Inhibitors, Novel Cancer Drugs, in Kidney Diseases

Inflammation is a crucial pathological feature in cancers and kidney diseases, playing a significant role in disease progression. Cyclin-dependent kinases CDK4 and CDK6 not only contribute to cell cycle progression but also participate in cell metabolism, immunogenicity and anti-tumor immune responses. Recently, CDK4/6 inhibitors have gained approval for investigational treatment of breast cancer and various other tumors. Kidney diseases and cancers commonly exhibit characteristic pathological features, such as the involvement of inflammatory cells and persistent chronic inflammation. Remarkably, CDK4/6 inhibitors have demonstrated impressive efficacy in treating non-cancerous conditions, including certain kidney diseases. Current studies have identified the renoprotective effect of CDK4/6 inhibitors, presenting a novel idea and potential direction for treating kidney diseases in the future. In this review, we briefly reviewed the cell cycle in mammals and the role of CDK4/6 in regulating it. We then provided an introduction to CDK4/6 inhibitors and their use in cancer treatment. Additionally, we emphasized the importance of these inhibitors in the treatment of kidney diseases. Collectively, growing evidence demonstrates that targeting CDK4 and CDK6 through CDK4/6 inhibitors might have therapeutic benefits in various cancers and kidney diseases and should be further explored in the future.

Exploring the Molecular Complexity of Medulloblastoma: Implications for Diagnosis and Treatment

Medulloblastoma is the most common malignant brain tumor in children. Over the last few decades, significant progress has been made in revealing the key molecular underpinnings of this disease, leading to the identification of distinct molecular subgroups with different clinical outcomes. In this review, we provide an update on the molecular landscape of medulloblastoma and treatment strategies. We discuss the four main molecular subgroups (WNT-activated, SHH-activated, and non-WNT/non-SHH groups 3 and 4), highlighting the key genetic alterations and signaling pathways associated with each entity. Furthermore, we explore the emerging role of epigenetic regulation in medulloblastoma and the mechanism of resistance to therapy. We also delve into the latest developments in targeted therapies and immunotherapies. Continuing collaborative efforts are needed to further unravel the complex molecular mechanisms and profile optimal treatment for this devastating disease.

Advances in Endocrine Therapy for Hormone Receptor-Positive Advanced Breast Cancer

PURPOSE OF REVIEW

To provide an overview of the current management of hormone receptor-positive (HR +) advanced breast cancer as well as highlight ongoing clinical investigation and novel therapies in development.

RECENT FINDINGS

CDK4/6 inhibition plus endocrine therapy is standard front-line therapy for HR + advanced breast cancer. Continuation of CDK4/6 inhibitors in combination with alternative endocrine therapy has been evaluated in the second-line setting. Alternatively, endocrine therapy in combination with PI3K/AKT pathway targeting agents has been studied, particularly in patients with PI3K pathway alterations. The oral SERD elacestrant has also been evaluated in patients with ESR1 mutation. Many novel endocrine agents and targeted agents are in development. An improved understanding of combination therapies and sequencing of therapies is needed to optimize the treatment paradigm. Biomarker development is needed to guide treatment decisions. Advances in the treatment of HR + breast cancer have resulted in improved patient outcomes in recent years. Continued development efforts with identification of biomarkers to better understand response and resistance to therapy are needed.

Targeting CDK1 in cancer: mechanisms and implications

Cyclin dependent kinases (CDKs) are serine/threonine kinases that are proposed as promising candidate targets for cancer treatment. These proteins complexed with cyclins play a critical role in cell cycle progression. Most CDKs demonstrate substantially higher expression in cancer tissues compared with normal tissues and, according to the TCGA database, correlate with survival rate in multiple cancer types. Deregulation of CDK1 has been shown to be closely associated with tumorigenesis. CDK1 activation plays a critical role in a wide range of cancer types; and CDK1 phosphorylation of its many substrates greatly influences their function in tumorigenesis. Enrichment of CDK1 interacting proteins with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was conducted to demonstrate that the associated proteins participate in multiple oncogenic pathways. This abundance of evidence clearly supports CDK1 as a promising target for cancer therapy. A number of small molecules targeting CDK1 or multiple CDKs have been developed and evaluated in preclinical studies. Notably, some of these small molecules have also been subjected to human clinical trials. This review evaluates the mechanisms and implications of targeting CDK1 in tumorigenesis and cancer therapy.

Cost Effectiveness of CDK4/6 Inhibitors in the First-Line Treatment of HR+/HER2- Metastatic Breast Cancer in Postmenopausal Women in the USA

BACKGROUND AND OBJECTIVE

Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors improve progression-free survival when combined with endocrine therapies in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer. However, the comparative cost effectiveness of utilizing three US Food and Drug Administration-approved CDK4/6 inhibitors is unknown. Therefore, we aimed to evaluate the cost effectiveness of individual CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib) with letrozole versus letrozole monotherapy in the first-line treatment of hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer in the USA.

METHODS

We constructed a Markov-based decision-analytic model to evaluate the cost effectiveness of CDK4/6 inhibitors plus endocrine therapies over a 40-year lifetime from a third-party payer perspective. The model incorporated health states (progression-free disease, progressive disease, and death), major adverse events (neutropenia), and cancer-specific and all-cause mortality. Using clinical efficacy and quality-of-life scores (utility) data from clinical trials, we estimated quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios using Medicare charges reported in US dollars per 2022 valuation and a discount rate of 3% applied to costs and outcomes. We performed deterministic and probabilistic sensitivity analyses to evaluate parametric and decision uncertainty.

RESULTS

Compared to letrozole, the model estimated an increase of 5.72, 5.87, and 6.39 in QALYs and costs of $799,178, $788,168, and $741,102 in combining palbociclib, ribociclib, and abemaciclib plus letrozole, respectively. Palbociclib or ribociclib plus letrozole were dominated by abemaciclib plus letrozole. Compared with letrozole, abemaciclib plus letrozole resulted in an incremental cost-effectiveness ratio of $457,538 per QALY with an incremental cost of $553,621 and an incremental QALY gain of 1.21. The results were sensitive to the cost of abemaciclib, disease progression utility, and patients' age.

CONCLUSIONS

At a willingness to pay of $100,000/QALY gained, our model predicts that combining CDK4/6 inhibitors plus letrozole is not cost effective with a marginal increase in QALYs at a high cost. Lowering the cost of these drugs or identifying patients who can receive maximal benefit from CDK4/6 inhibitors would improve the value of this regimen in patients.

Combination Therapies with Kinase Inhibitors for Acute Myeloid Leukemia Treatment

Targeting kinase activity is considered to be an attractive therapeutic strategy to overcome acute myeloid leukemia (AML) since aberrant activation of the kinase pathway plays a pivotal role in leukemogenesis through abnormal cell proliferation and differentiation block. Although clinical trials for kinase modulators as single agents remain scarce, combination therapies are an area of therapeutic interest. In this review, the author summarizes attractive kinase pathways for therapeutic targets and the combination strategies for these pathways. Specifically, the review focuses on combination therapies targeting the FLT3 pathways, as well as PI3K/AKT/mTOR, CDK and CHK1 pathways. From a literature review, combination therapies with the kinase inhibitors appear more promising than monotherapies with individual agents. Therefore, the development of efficient combination therapies with kinase inhibitors may result in effective therapeutic strategies for AML.

An Interpretable Multitask Framework BiLAT Enables Accurate Prediction of Cyclin-Dependent Protein Kinase Inhibitors

The cyclin-dependent protein kinases (CDKs) are protein-serine/threonine kinases with crucial effects on the regulation of cell cycle and transcription. CDKs can be a hallmark of cancer since their excessive expression could lead to impaired cell proliferation. However, the selectivity profile of most developed CDK inhibitors is not enough, which have hindered the therapeutic use of CDK inhibitors. In this study, we propose a multitask deep learning framework called BiLAT based on SMILES representation for the prediction of the inhibitory activity of molecules on eight CDK subtypes (CDK1, 2, 4-9). The framework is mainly composed of an improved bidirectional long short-term memory module BiLSTM and the encode layer of the Transformer framework. Additionally, the data enhancement method of SMILES enumeration is applied to improve the performance of the model. Compared with baseline predictive models based on three conventional machine learning methods and two multitask deep learning algorithms, BiLAT achieves the best performance with the highest average AUC, ACC, F1-score, and MCC values of 0.938, 0.894, 0.911, and 0.715 for the test set. Moreover, we constructed a targeted external data set CDK-Dec for the CDK family, which mainly contains bait values screened by 3D similarity with active compounds. This dataset was utilized in the subsequent evaluation of our model. It is worth mentioning that the BiLAT model is interpretable and can be used by chemists to design and synthesize compounds with improved activity. To further verify the generalization ability of the multitask BiLAT model, we also conducted another evaluation on three public datasets (Tox21, ClinTox, and SIDER). Compared with several currently popular models, BiLAT shows the best performance on two datasets. These results indicate that BiLAT is an effective tool for accelerating drug discovery.

Structural basis of CDK3 activation by cyclin E1 and inhibition by dinaciclib

Cell cycle transitions are controlled by multiple cell cycle regulators, especially CDKs. Several CDKs, including CDK1-4 and CDK6, promote cell cycle progression directly. Among them, CDK3 is critically important because it triggers the transitions of G0 to G1 and G1 to S phase through binding to cyclin C and cyclin E1, respectively. In contrast to its highly related homologs, the molecular basis of CDK3 activation remains elusive due to the lack of structural information of CDK3, particularly in cyclin bound form. Here we report the crystal structure of CDK3 in complex with cyclin E1 at 2.25 Å resolution. CDK3 resembles CDK2 in that both adopt a similar fold and bind cyclin E1 in a similar way. The structural discrepancy between CDK3 and CDK2 may reflect their substrate specificity. Profiling a panel of CDK inhibitors reveals that dinaciclib inhibits CDK3-cyclin E1 potently and specifically. The structure of CDK3-cyclin E1 bound to dinaciclib reveals the inhibitory mechanism. The structural and biochemical results uncover the mechanism of CDK3 activation by cyclin E1 and lays a foundation for structural-based drug design.

Cyclins and cyclin-dependent kinases: from biology to tumorigenesis and therapeutic opportunities

The discussion on cell proliferation cannot be continued without taking a look at the cell cycle regulatory machinery. Cyclin-dependent kinases (CDKs), cyclins, and CDK inhibitors (CKIs) are valuable members of this system and their equilibrium guarantees the proper progression of the cell cycle. As expected, any dysregulation in the expression or function of these components can provide a platform for excessive cell proliferation leading to tumorigenesis. The high frequency of CDK abnormalities in human cancers, together with their druggable structure has raised the possibility that perhaps designing a series of inhibitors targeting CDKs might be advantageous for restricting the survival of tumor cells; however, their application has faced a serious concern, since these groups of serine-threonine kinases possess non-canonical functions as well. In the present review, we aimed to take a look at the biology of CDKs and then magnify their contribution to tumorigenesis. Then, by arguing the bright and dark aspects of CDK inhibition in the treatment of human cancers, we intend to reach a consensus on the application of these inhibitors in clinical settings.

A mass balance study of [14C]SHR6390 (dalpiciclib), a selective and potent CDK4/6 inhibitor in humans

SHR6390 (dalpiciclib) is a selective and effective cyclin-dependent kinase (CDK) 4/6 inhibitor and an effective cancer therapeutic agent. On 31 December 2021, the new drug application was approved by National Medical Product Administration (NMPA). The metabolism, mass balance, and pharmacokinetics of SHR6390 in 6 healthy Chinese male subjects after a single oral dose of 150 mg [14C]SHR6390 (150 µCi) in this research. The Tmax of SHR6390 was 3.00 h. In plasma, the t1/2 of SHR6390 and its relative components was approximately 17.50 h. The radioactivity B/P (blood-to-plasma) AUC0-t ratio was 1.81, indicating the preferential distribution of drug-related substances in blood cells. At 312 h after administration, the average cumulative excretion of radioactivity was 94.63% of the dose, including 22.69% in urine and 71.93% in stool. Thirteen metabolites were identified. In plasma, because of the low level of radioactivity, only SHR6390 was detected in pooled AUC0-24 h plasma. Stool SHR6390 was the main component in urine and stool. Five metabolites were identified in urine, and 12 metabolites were identified in stool. Overall, faecal clearance is the main method of excretion.

Role of identified proteins in the proteome profiles of CDK4/6 inhibitor-resistant breast cancer cell lines

Abemaciclib (Ab) and palbociclib (Pb) are CDK4/6 inhibitors used to cure advanced breast cancer (BC). However, acquired resistance is a major challenge. The molecular mechanisms and signature proteins of therapy resistance for Ab and Pb drugs need to be explored. Here we developed resistant cells for Ab and Pb drugs in MCF-7 cell lines and explored the mechanisms and signature proteins of therapy resistance in BC. Proteome profiling was performed using the label-free proteome-orbitrap-fusion-MS-MS technique. Gene ontology (GO)-terms, KEGG pathways and network analysis were performed for the proteome data. Drug-resistant cells showed increased drug tolerance, enhanced colony formation potential and an increased gap-healing tendency for the respective drug. Up-regulation of survival genes (BCL-2 and MCL-1) and down-regulation of apoptosis inducers were observed. Drug-resistance markers (MDR-1 and ABCG2 (BCRP)) along with ESR-1, CDK4, CDK6, and cyclin-D1 genes were up-regulated in resistant cells. A total of 237 and 239 proteins were found to be differentially expressed in the Ab and Pb-resistant cells, respectively. Down-regulated proteins induce apoptosis signalling and nucleotide metabolisms and restrict EGFR signalling; however, up-regulated proteins induce Erk, wnt-β-catenin, VEGFR-PI3K-AKT, glucose transportation, and hypoxia signalling pathways and regulate hydrogen peroxide signalling pathways. The panel of identified proteins associated with these pathways might have characteristics of molecular signature and new drug targets for overcoming drug resistance in breast cancer.

Integrating a phenotypic screening with a structural simplification strategy to identify 4-phenoxy-quinoline derivatives to potently disrupt the mitotic localization of Aurora kinase B

We combined a mechanism-informed phenotypic screening (MIPS) assay with a structural simplification strategy to guide the discovery of compounds that disrupt the localization of the mitotic regulator, Aurora kinase B (AURKB), rather than inhibiting its catalytic activity. An initial hit 4-(4-methylthiophen-2-yl)-N-(4-(quinolin-4-yloxy)phenyl)phthalazin-1-amine was identified after screening an in-house library of small molecules and phenocopied the loss of function mutations in AURKB without inhibiting its catalytic activity. We isolated this hit compound activity to its 4-phenoxy-quinoline moiety. The fragment was further optimized into a class of new chemical entities that potently disrupt the mitotic localization of AURKB at low nanomolar concentrations and consequently elicit severe growth inhibition in diverse human cancer cell lines. A lead compound, N-(3-methoxy-5-(6-methoxyquinolin-4-yl)oxy)phenyl)acetamide possessed desirable pharmacokinetic properties such as AUC_0-∞: 227.15 [ng∙h/mL/(mg/kg)]; C_max: 3378.52 ng/mL T_1/2: 3.52 h; and F%: 42 % and produced the AURKB-inhibitory phenotypes in a mouse xenograft model. A lead compound is a powerful tool for interrogating the regulation of AURKB and has the potential to be further developed as a first-in-class oncology therapeutic.

Revealing active components and action mechanism of Fritillariae Bulbus against non-small cell lung cancer through spectrum-effect relationship and proteomics

BACKGROUND

Fritillariae Bulbus (FB) is widely used as a traditional medicine for the treatment of lung meridian diseases. It has been proved that FB has good anti-non-small cell lung cancer (NSCLC) activity. However, the active components and potential mechanism are still not clear.

PURPOSE

To reveal the bioactive components of FB against NSCLC and potential mechanism through spectrum-effect relationship and proteomics.

METHOD

First, the FB extract was chemically profiled by UHPLC-QTOF-MS and the inhibitory effect of FB extract on A549 cell viability was evaluated by Cell Counting Kit-8 assay. Second, orthogonal-partial least squares-regression analysis was applied to screen potential active compounds through correlating the chemical profile with corresponding inhibitory effect. Third, the anti-NSCLC activities of potential active components were further investigated in terms of cell proliferation, cell cycle and cell apoptosis in vitro and tumor growth in vivo. Finally, proteomics was utilized to reveal the underlying anti-NSCLC mechanism.

RESULTS

Six potential active components including verticine, verticinone, zhebeirine, ebeiedinone, yibeissine and peimisine were screened out by spectrum-effect relationship. Among them, zhebeirine showed higher inhibitory effect on A549 cell viability with IC₅₀ value of 36.93 μM and dosage-dependent inhibition of A549 xenograft tumor growth in nude mice. Proteomics and western blotting assays indicated that zhebeirine could arrest cell cycle by down-regulating the expressions of CDK1, CDK2, Cyclin A2, Cyclin B2 and inhibiting the phosphorylation of p53. Moreover, the proteins participating in p53 signaling pathway including PCNA, 14-3-3σ, CHEK1 were significantly decreased, which suggested that zhebeirine affected cell cycle progression through p53 signaling pathway.

CONCLUSION

This study not only provides scientific evidence to support the clinical application of FB against NSCLC, but also demonstrates that zhebeirine is a promising anti-NSCLC lead compound deserving further studies.

Deciphering the Immunomodulatory Role of Cyclin-Dependent Kinase 4/6 Inhibitors in the Tumor Microenvironment

Cancer is characterized by persistent cell proliferation driven by aberrant cell cycle regulation and stimulation of cyclin-dependent kinases (CDKs). A very intriguing and potential approach for the development of antitumor medicines is the suppression of CDKs that lead to induction of apoptosis and cell cycle arrest. The shift of the cell cycle from the G0/G1 phase to the S phase, which is characterized by active transcription and synthesis, depends on the development of the cyclin D-CDK4/6 complex. A precise balance between anticancer activity and general toxicity is demonstrated by CDK inhibitors, which can specifically block CDK4/6 and control the cell cycle by reducing the G1 to S phase transition. CDK4/6 inhibitors have recently been reported to exhibit significant cell growth inhibition via modulating the tumour microenvironment in cancerous cells. One significant new understanding is that these inhibitors serve important functions in the interaction among tumour cells and the host immune system in addition to being cytostatic. Herein, we discuss the biological significance of CDK4/6 inhibitors in cancer therapeutics, as well as their biological impact on T cells and other important immune cells. Furthermore, we explore the integration of preclinical findings of these pharmaceuticals' ability to enhance antitumor immunity.

Cyclin-dependent kinases in cancer: Role, regulation, and therapeutic targeting

Regulated cell division is one of the fundamental phenomena which is the basis of all life on earth. Even a single base pair mutation in DNA leads to the production of the dysregulated protein that can have catastrophic consequences. Cell division is tightly controlled and orchestrated by proteins called cyclins and cyclin-dependent kinase (CDKs), which serve as licensing factors during different phases of cell division. Dysregulated cell division is one of the most important hallmarks of cancer and is commonly associated with a mutation in cyclins and CDKs along with tumor suppressor proteins. Therefore, targeting the component of the cell cycle which leads to these characteristics would be an effective strategy for treating cancers. Specifically, Cyclin-dependent kinases (CDKs) involved in cell cycle regulation have been identified to be overexpressed in many cancers. Many studies indicate that oncogenesis occurs in cancerous cells by the overactivity of different CDKs, which impact cell cycle progression and checkpoint dysregulation which is responsible for development of tumor. The development of CDK inhibitors has emerged as a promising and novel approach for cancer treatment in both solid and hematological malignancies. Some of the novel CDK inhibitors have shown remarkable results in clinical trials, such as-Ribociclib®, Palbociclib® and Abemaciclib®, which are CDK4/6 inhibitors and have received FDA approval for the treatment of breast cancer. In this chapter, we discuss the molecular mechanism through which cyclins and CDKs regulate cell cycle progression and the emergence of cyclins and CDKs as rational targets in cancer. We also discuss recent advances in developing CDK inhibitors, which have emerged as a novel class of inhibitors, and their associated toxicities in recent years.

Computational screening and structural analysis of Gly201Arg and Gly201Asp missense mutations in human cyclin-dependent kinase 4 protein

The regulatory proteins, cyclins, and cyclin-dependent kinases (CDKs) control the cell cycle progression. CDK4 gene mutations are associated with certain cancers such as melanoma, breast cancer, and rhabdomyosarcoma. Therefore, understanding the mechanisms of cell cycle control and cell proliferation is essential in developing cancer treatment regimens. In this study, we obtained cancer-causing CDK4 mutations from the COSMIC database and subjected them to a series of in silico analyses to identify the most significant mutations. An overall of 238 mutations (119 missense mutations) retrieved from the COSMIC database were investigated for the pathogenic and destabilizing properties using the PredictSNP and iStable algorithms. Further, the amino acid position of the most pathogenic and destabilizing mutations were analyzed to understand the nature of amino acid conservation across the species during the evolution. We observed that the missense mutations G201R and G201D were more significant and the Glycine at position 201 was found to highly conserved. These significant mutations were subjected to molecular dynamics simulation analysis to understand the protein's structural changes. The results from molecular dynamics simulations revealed that both G201R and G201D of CDK4 are capable of altering the protein's native form. On comparison among the most significant mutations, G201R disrupted the protein structure higher than the protein with G201D.

Anti-cancer drug molecules targeting cancer cell cycle and proliferation

Cancer, a vicious clinical burden that potentiates maximum fatality for humankind, arises due to unregulated excessive cell division and proliferation through an eccentric expression of cell cycle regulator proteins. A set of evolutionarily conserved machinery controls the cell cycle in an extremely precise manner so that a cell that went through the cycle can produce a genetically identical copy. To achieve perfection, several checkpoints were placed in the cycle for surveillance; so, errors during the division were rectified by the repair strategies. However, irreparable damage leads to exit from the cell cycle and induces programmed cell death. In comparison to a normal cell, cancer cells facilitate the constitutive activation of many dormant proteins and impede negative regulators of the checkpoint. Extensive studies in the last few decades on cell division and proliferation of cancer cells elucidate the molecular mechanism of the cell-cycle regulators that are often targeted for the development of anti-cancer therapy. Each phase of the cell cycle has been regulated by a unique set of proteins including master regulators Cyclins, and CDKs, along with the accessory proteins such as CKI, Cdc25, error-responsive proteins, and various kinase proteins mainly WEE1 kinases, Polo-like kinases, and Aurora kinases that control cell division. Here in this chapter, we have analytically discussed the role of cell cycle regulators and proliferation factors in cancer progression and the rationale of using various cell cycle-targeting drug molecules as anti-cancer therapy.

Sensitization of cervical cancer cells to radiation by the cyclin-dependent kinase inhibitor dinaciclib

Dinaciclib is a selective cyclin-dependent kinase inhibitor, but its radiosensitizing effect remains unclear. The aim of this study is to investigate the radiosensitizing effect of Dinaciclib on cervical cancer cells. Two cervical cancer cell lines, Hela and Siha, were selected, and the IC50 was determined by CCK8. The radiosensitizing effect of Dinaciclib was verified by plate cloning assay, and the G2/M phase arrest and apoptosis of IR cells were verified by flow cytometry. Immunofluorescence assay was used to verify the formation of γH2AX foci following DNA damage. Western blot was performed to detect cell cycle, apoptosis, autophagy, and DNA damage-related pathways. Dinaciclib increased the cell sensitivity to IR. IR induced G2/M phase arrest and apoptosis, and Dinaciclib enhanced this effect. Further, Dinaciclib delayed DNA repair, including non-homologous end joining repair and homologous recombination repair, and reduced the expression of DNA repair proteins Ku80 (SiHa cells), Ku70, and RAD51, as well as the expression of apoptotic marker Bcl-2. The expression of autophagy marker Beclin1 induced tumor cell death and increased the formation of DNA damage marker γH2AX foci. Dinaciclib improves the sensitivity of cervical cancer cells to IR by inducing cell cycle arrest, delaying DNA repair, and increasing apoptosis. However, further research is needed to unravel the complexity of DNA repair pathways.

Pralatrexate mediates effective killing of gemcitabine-resistant pancreatic cancer: role of mTOR/4E-BP1 signal pathway

Gemcitabine is the first-line chemotherapeutic agent for pancreatic cancer. However, gemcitabine-resistance frequently leads to poor prognosis. Exploring new chemotherapeutic agents is important for patients with gemcitabine-resistant pancreatic cancer. In this study, we established a new acquired gemcitabine-resistant pancreatic cancer cell line BxPC-GEM-20 from parental BxPC-3. We found that pralatrexate significantly inhibited the growth of BxPC-GEM-20. The half-maximal inhibitory concentration of pralatrexate on BxPC-GEM-20 cell was about 3.43 ± 0.25 nM. Pralatrexate was found to effectively inhibit the clonal growth of BxPC-GEM-20 cell. Additionally, pralatrexate at 20 mg/kg had an excellent tumor inhibitory effect with an inhibitory rate of 76.92% in vivo. This pralatrexate therapy showed good safety profile that with little to no additional influence on the hepatic, renal function as well as body weight changes in nude mice. Pralatrexate was confirmed to prevent cells from entering the G2/M phase, leading to the promotion of apoptosis and autophagy. Further analysis demonstrated that the reduced phosphorylation of mTOR played a significant role in the tumor cell damage caused by pralatrexate. Pralatrexate effectively inhibited the mTOR/4E-BP1 pathway. Activation of mTOR pathway can further obstruct the repressive effect of pralatrexate on gemcitabine-resistant pancreatic cancer. In summary, pralatrexate induces effective inhibition of gemcitabine-resistant pancreatic cancer. This may lead to the expansion of pralatrexate's application and offer benefit to gemcitabine-resistant pancreatic cancer patients in the future.

Targeting CDK7 in oncology: The avenue forward

Cyclin-dependent kinase (CDK) 7 is best characterized for the ability to regulate biological processes, including the cell cycle and gene transcription. Abnormal CDK7 activity is observed in various tumours and represents a driving force for tumourigenesis. Therefore, CDK7 may be an appealing target for cancer treatment. Whereas, the enthusiasm for CDK7-targeted therapeutic strategy is mitigated due to the widely possessed belief that this protein is essential for normal cells. Indeed, the fact confronts the consensus. This is the first review to introduce the role of CDK7 in pan-cancers via a combined analysis of comprehensive gene information and (pre)clinical research results. We also discuss the recent advances in protein structure and summarize the understanding of mechanisms underlying CDK7 function. These endeavours highlight the pivotal roles of CDK7 in tumours and may contribute to the development of effective CDK7 inhibitors within the strategy of structure-based drug discovery for cancer therapy.

Antitumor response and quality of life: is there a need to sacrifice? Clinical observation: long-term and safe control of the disease using a combination of ribociclib with letrozole. Case report

Metastatic luminal B HER2-negative breast cancer (HR+/HER2- mBC) occupies a leading place in the global structure of morbidity and mortality among women. The current gold standard of first-line treatment is the combination of CDK4/6 inhibitors with aromatase inhibitors, among which ribociclib with letrozole is distinguished. According to the MONALEESA-2 study, the addition of ribociclib to letrozole significantly increased the median overall survival to 63.9 months, reducing the risk of death by 24%. The safety profile of the combination is manageable, and the development of adverse events led to the interruption of therapy only in 7.5% of cases. A study of the actual clinical practice of CompLEEment-1 also confirmed the safety and effectiveness of the combination. Maintaining and improving the quality of life is one of the main tasks in the treatment of patients with HR+/HER2- mBC. According to the MONALEESA-2 study, the addition of ribociclib significantly affects the maintenance of quality of life and leads to a decrease in the intensity of pain syndrome. The published data allowed us to assign a combination of ribociclib and letrozole 4 points on the ESMO-MCBS scale. The safety of long-term use of the combination in the first line of treatment illustrated by clinical observation. The patient's progression-free survival during therapy was 40 months, which significantly exceeds the data of the MONALEESA-2 and CompLEEment-1 studies. The maximum effect (partial response according to RECIST 1.1 -40%) achieved after 24 weeks and persisted for 24 months. Clinically, the patient noted a decrease in the severity of the pain syndrome after 8 weeks of therapy. Against the background of therapy, it was possible to maintain the quality of life without sacrificing antitumor efficacy.