Cancer Cell Cycle Regulation Research Articles

Unveiling the potency of FDA-approved oxidopamine HBr for cervical cancer regulation and replication proteins.

Cervical Cancer remains a women's health concern worldwide and ranks among the most prevalent cancers, particularly in developing countries. Many women are diagnosed with cervical cancer, with a substantial number succumbing to the disease even after the availability of vaccines and drugs. The tumour microenvironment often exhibits immune evasion, including suppression of T-cell activity and altered cytokine, impacting the efficacy of therapeutic interventions and highlighting the need for treatments to modulate the immune response. Despite efforts to promote HPV vaccination and regular screenings, it causes many deaths, underscoring the urgent need for continued research, healthcare access, and rapid drug development or repurposing. In this study, we identified various proteins involved in cervical cancer cell cycle regulation and DNA replication proteins, performed the multitargeted docking with an FDA-approved library, and identified Oxidopamine HBr as a multitargeted drug. Studies extended with pharmacokinetics and compared with the standard values followed by DFT, which supported the compound as a multitargeted inhibitor. Further, the docked complexes were taken for the interaction fingerprints, and it was identified that there are many 9 polar, 5 hydrophobic, 2 aromatic, and 2 basic residues. We extended our studies for 100ns MD Simulation in water, and the computations explored the deviation and fluctuations under 2Å and many intermolecular interactions; the same trajectory files were used for the MM\GBSA studies. All the studies have supported the Oxidopamine HBr as a cervical cancer multitargeted inhibitor-however, experimental studies are needed before human use.

CDKL3 is a targetable regulator of cell cycle progression in cancers.

Cell cycle regulation is largely abnormal in cancers. Molecular understanding and therapeutic targeting of the aberrant cell cycle are essential. Here, we identified that an underappreciated serine/threonine kinase, cyclin-dependent kinase-like 3 (CDKL3), crucially drives rapid cell cycle progression and cell growth in cancers. With regard to mechanism, CDKL3 localizes in the nucleus and associates with specific cyclin to directly phosphorylate retinoblastoma (Rb) for quiescence exit. In parallel, CDKL3 prevents the ubiquitin-proteasomal degradation of cyclin-dependent kinase 4 (CDK4) by direct phosphorylation on T172 to sustain G1 phase advancement. The crucial function of CDKL3 in cancers was demonstrated both in vitro and in vivo. We also designed, synthesized, and characterized a first-in-class CDKL3-specific inhibitor, HZ1. HZ1 exhibits greater potency than CDK4/6 inhibitor in pan-cancer treatment by causing cell cycle arrest and overcomes acquired resistance to CDK4/6 inhibitor. In particular, CDKL3 has significant clinical relevance in colon cancer, and the effectiveness of HZ1 was demonstrated by murine and patient-derived cancer models. Collectively, this work presents an integrated paradigm of cancer cell cycle regulation and suggests CDKL3 targeting as a feasible approach in cancer treatment.

Circular RNAs in Cell Cycle Regulation of Cancers.

Cancer has been one of the most problematic health issues globally. Typically, all cancers share a common characteristic or cancer hallmark, such as sustaining cell proliferation, evading growth suppressors, and enabling replicative immortality. Indeed, cell cycle regulation in cancer is often found to be dysregulated, leading to an increase in aggressiveness. These dysregulations are partly due to the aberrant cellular signaling pathway. In recent years, circular RNAs (circRNAs) have been widely studied and classified as one of the regulators in various cancers. Numerous studies have reported that circRNAs antagonize or promote cancer progression through the modulation of cell cycle regulators or their associated signaling pathways, directly or indirectly. Mostly, circRNAs are known to act as microRNA (miRNA) sponges. However, they also hold additional mechanisms for regulating cellular activity, including protein binding, RNA-binding protein (RBP) recruitment, and protein translation. This review will discuss the current knowledge of how circRNAs regulate cell cycle-related proteins through the abovementioned mechanisms in different cancers.

Regulatory miRNAs, circRNAs and lncRNAs in cell cycle progression of breast cancer.

Breast cancer is a complex and heterogeneous disease that poses a significant public health concern worldwide, and it remains a major challenge despite advances in treatment options. One of the main properties of cancer cells is the increased proliferative activity that has lost regulation. Dysregulation of various positive and negative modulators in the cell cycle has been identified as one of the driving factors of breast cancer. In recent years, non-coding RNAs have garnered much attention in the regulation of cell cycle progression, with microRNAs (miRNAs), circular RNAs (circRNAs), and long non-coding RNAs (lncRNAs) being of particular interest. MiRNAs are a class of highly conserved and regulatory small non-coding RNAs that play a crucial role in the modulation of various cellular and biological processes, including cell cycle regulation. CircRNAs are a novel form of non-coding RNAs that are highly stable and capable of modulating gene expression at posttranscriptional and transcriptional levels. LncRNAs have also attracted considerable attention because of their prominent roles in tumor development, including cell cycle progression. Emerging evidence suggests that miRNAs, circRNAs and lncRNAs play important roles in the regulation of cell cycle progression in breast cancer. Herein, we summarized the latest related literatures in breast cancer that emphasize the regulatory roles of miRNAs, circRNAs and lncRNAs in cell cycle progress of breast cancer. Further understanding of the precise roles and mechanisms of non-coding RNAs in breast cancer cell cycle regulation could lead to the development of new diagnostic and therapeutic strategies for breast cancer.

KDM5D Histone Demethylase Identifies Platinum-Tolerant Head and Neck Cancer Cells Vulnerable to Mitotic Catastrophe

Head and neck squamous cell carcinoma (HNSCC) is a major contributor to cancer incidence globally and is currently managed by surgical resection followed by adjuvant chemoradiotherapy. However, local recurrence is the major cause of mortality, indicating the emergence of drug-tolerant persister cells. A specific histone demethylase, namely lysine-specific demethylase 5D (KDM5D), is overexpressed in diverse types of cancers and involved in cancer cell cycle regulation. However, the role of KDM5D in the development of cisplatin-tolerant persister cells remains unexplored. Here, we demonstrated that KDM5D contributes to the development of persister cells. Aurora Kinase B (AURKB) disruption affected the vulnerability of persister cells in a mitotic catastrophe-dependent manner. Comprehensive in silico, in vitro, and in vivo experiments were performed. KDM5D expression was upregulated in HNSCC tumor cells, cancer stem cells, and cisplatin-resistant cells with biologically distinct signaling alterations. In an HNSCC cohort, high KDM5D expression was associated with a poor response to platinum treatment and early disease recurrence. KDM5D knockdown reduced the tolerance of persister cells to platinum agents and caused marked cell cycle deregulation, including the loss of DNA damage prevention, and abnormal mitosis-enhanced cell cycle arrest. By modulating mRNA levels of AURKB, KDM5D promoted the generation of platinum-tolerant persister cells in vitro, leading to the identification of the KDM5D/AURKB axis, which regulates cancer stemness and drug tolerance of HNSCC. Treatment with an AURKB inhibitor, namely barasertib, resulted in a lethal consequence of mitotic catastrophe in HNSCC persister cells. The cotreatment of cisplatin and barasertib suppressed tumor growth in the tumor mouse model. Thus, KDM5D might be involved in the development of persister cells, and AURKB disruption can overcome tolerance to platinum treatment in HNSCC.

Deciphering the signaling mechanisms of β-arrestin1 and β-arrestin2 in regulation of cancer cell cycle and metastasis.

β-Arrestins are ubiquitously expressed intracellular proteins with many functions which interact directly and indirectly with a wide number of cellular partners and mediate downstream signaling. Originally, β-arrestins were identified for their contribution to GPCR desensitization to agonist-mediated activation, followed by receptor endocytosis and ubiquitylation. However, current investigations have now recognized that in addition to GPCR arresting (hence the name arrestin). β-Arrestins are adaptor proteins that control the recruitment, activation, and scaffolding of numerous cytoplasmic signaling complexes and assist in G-protein receptor signaling, thus bringing them into close proximity. They have participated in various cellular processes such as cell proliferation, migration, apoptosis, and transcription via canonical and noncanonical pathways. Despite their significant recognition in several physiological processes, these activities are also involved in the onset and progression of various cancers. This review delivers a concise overview of the role of β-arrestins with a primary emphasis on the signaling processes which underlie the mechanism of β-arrestins in the onset of cancer. Understanding these processes has important implications for understanding the therapeutic intervention and treatment of cancer in the future.

Identification and clinical validation of NUSAP1 as a novel prognostic biomarker in ovarian cancer

BackgroundNucleolar and spindle-associated protein 1 (NUSAP1) was shown to be involved in cell cycle regulation in cancer. However, its prognostic value and underlying mechanism in ovarian cancer remain unclear.MethodsOncomine, TCGA, CCLE, and UALCAN databases were used to analyze the expression level of NUSAP1 in ovarian cancer. The Kaplan–Meier plotter database was used to evaluate its prognostic value. The results from these analyses were further validated using immunohistochemical assay. The potential molecular mechanism of NUSAP1 in ovarian cancer was assessed with respect to homologous recombination repair, mismatch repair, and immunology using different databases.ResultsDatabase analyses and experimental results demonstrated that NUSAP1 was highly expressed in ovarian cancer, its levels being correlated with the FIGO stage. High NUSAP1 expression was an independent risk factor affecting the prognosis of patients with epithelial ovarian cancer. Moreover, NUSAP1 was associated with cell cycle, DNA replication, homologous recombination, and p53 signaling pathway. A positive correlation was identified between the expression of NUSAP1 and BRCA1/2 in ovarian cancer. In addition, NUSAP1 was associated with the expression of DNA mismatch repair genes and immune cell infiltration.ConclusionsNUSAP1 may be a valuable prognostic marker, as well as a novel biomarker for evaluating the response to immunotherapy of patients with ovarian cancer.

Molecular mechanisms of the lipopeptides from Bacillus subtilis in the apoptosis of cancer cells - A review on its Current Status in different cancer cell lines

Cancer treatment is an economic burden because of the very expensive drugs which depend on improvement in modern technology. Furthermore, the rate of success of cancer treatments is not actually satisfying. Several experimental investigations are going on the alternative therapeutics directed at lessening the undesirable effects of medications enhancing the patient's survival rates. Bacillus subtilis has the ability to produce different stable bioactive molecules over a wide range of temperature, pH, and enzymes. The lipopeptides from Bacillus subtilis have significant potential to inhibit different tumor cell lines such as breast cancer, lung cancer, colon cancer, oral cancer, pancreatic cancer, liver cancer, cervical cancer, gastric cancer. Lipopeptides have interacted with the cancer cell cycle regulation by influencing the cell cycle checkpoints, regulatory proteins, and signaling pathways and interfere with the downstream signaling. This review gives an overview of the potential bioactive compounds from the Bacillus subtilis that efficiently treat various cancer cell lines through apoptosis, paraptosis, and autophagy. Furthermore, this review comprehensively summarizes the molecular mechanism of lipopetides like iturin, surfactin, and fengycin from Bacillus subtilis to treat several cancer types by influencing the cell cycle checkpoints, regulatory proteins, and signaling pathways.

In Vitro Effect and Mechanism of Action of Ergot Alkaloid Dihydroergocristine in Chemoresistant Prostate Cancer Cells.

Chemoresistance is a major obstacle in the treatment of prostate cancer (PCa). It is imperative to develop novel strategies for overcoming chemoresistance and improving clinical outcomes. We evaluated the in vitro activity and mechanism of action of dihydroergocristine (DHECS), an ergot alkaloid approved for the treatment of dementia, in PCa cells. The in vitro effects of DHECS on PCa cell cycle and viability were determined by flow cytometry and colorimetric assay. The effects of DHECS on PCa cell signaling were evaluated by quantitative PCR, western blot analysis and reporter assay. DHECS was effective in inducing cell cycle arrest and apoptosis in human PCa cells. Of particular interest, DHECS demonstrated high potency against chemoresistant PCa cells. At the molecular level, DHECS affected multiple factors implicated in the regulation of cancer cell cycle and programmed cell death, including p53, mouse double minute 2 homolog (MDM2), retinoblastoma protein (RB), p21, E2F transcription factor 1 (E2F1), survivin, myeloid cell leukemia 1 (Mcl-1) and poly ADP ribose polymerase (PARP). Furthermore, DHECS may function through dopamine receptor-mediated effects on 5'-AMP-activated protein kinase (AMPK) and nuclear factor kappa B (NF-ĸB). DHECS has the potential to be repurposed as a novel anticancer agent for the management of chemoresistant PCa.

Over-expression of HDAC8 down-regulate CDKN2A is associated with worse prognosis of esophageal squamous cell carcinoma.

BackgroundThe epigenetic alteration has an impact on cancer cell cycle regulation. Expression of histone deacetylase 8 (HDAC8) ruled out the expression of cyclin-dependent kinase inhibitor 2A (CDKN2A) and this is linked with the prognosis of Esophageal cancer (EC) patients.MethodsBy the immunohistochemical staining, we examined the expression status of HDAC8 and CDKN2A protein of 110 esophageal squamous cell carcinoma (ESCC) patients in the tissue microarray. The nuclear staining intensity was counted by immunoreactivity scoring ranging from 0 to 12 and grouped them into two; weak or non-expression and over-expression.ResultsThe median follow-up duration of our study was 71 months postoperatively. Up-regulation of HDAC8 expression and down-regulation of CDKN2A (p16) indicate decreased 5-year overall survival (OS) (P=0.003) and (P=0.001) respectively and progression-free survival (PFS) (P=0.005, P=0.001) respectively, which are statistically significant and determined by Kaplan-Meier estimates using log-rank test. Consequently, HDAC8 and CDKN2A act as an independent prognostic biomarker, for OS and PFS that analyzed by multivariate cox-regression analysis, HR 1.173 with 95% CI: 0.215–6.416 and P=0.003 and HR 1.217 with 95% CI: 0.224–6.600 and P=0.005 respectively. Spearman rank test establish the negative correlation between HDAC8 and CDKN2A.ConclusionsOver-expression of HDAC8 and weak or no expression of CDKN2A have a worse impact on EC patients and indicate poor survival and progression of the disease and act as a promising prognostic parameter.

Computational Molecular Modeling of Pin1 Inhibition Activity of Quinazoline, Benzophenone, and Pyrimidine Derivatives

Pin1 (peptidyl-prolyl cis-trans isomerase NIMA-interacting 1) is directly involved in cancer cell-cycle regulation because it catalyses the cis-trans isomerization of prolyl amide bonds in proteins. In this sense, a modeling evaluation of the inhibition of Pin1 using quinazoline, benzophenone, and pyrimidine derivatives was performed by using multilinear, random forest, SMOreg, and IBK regression algorithms on a dataset of 51 molecules, which was divided randomly in 78% for the training and 22% for the test set. Topological descriptors were used as independent variables and the biological activity (pIC50) as a dependent variable. The most robust individual model contained 9 features, and its predictive capability was statistically validated by the correlation coefficient for adjusting, 10-fold cross validation, test set, and bootstrapping with values of 0.910, 0.819, 0.841, and 0.803, respectively. In order to improve the prediction of the pIC50 values, the aggregation of the individual models was performed through the construction of an ensemble, and the most robust one was constructed by two individual models (LR3 and RF1) by applying the IBK algorithm, and a substantial improvement in predictive performance is reflected in the values of R2ADJ = 0.982, Q2CV = 0.962, and Q2EXT = 0.918. Mean square errors <0.165 and good fitting between calculated and experimental pIC50 values suggest a robustness on the prediction of pIC50. Regarding the docking simulation, a binding affinity between the molecules and the active site for the Pin1 inhibition into the protein (3jyj) was estimated through the calculation of the binding free energy (BE), with values in the range of −5.55 to −8.00 kcal/mol, implying a stabilizing interaction molecule receptor. The ligand interaction diagrams between the drugs and amino acid in the binding site for the three most active compounds denoted a good wrapper of these organic compounds into the protein mainly by polar amino acids.

PROTACs suppression of CDK4/6, crucial kinases for cell cycle regulation in cancer.

PROTACs based on two selective, FDA approved, CDK4/6 inhibitors were formed. One of them, based on palbociclib, potently initiates degradation of these CDK proteins, and suppresses phosphorylation of retinoblastoma protein (Rb) leading to cell cycle arrest. These PROTACs are active at nanomolar concentrations, and appear to be the first for CDK4/6.

PO-479 NUB1 as a prognostic marker in breast cancer: a retrospective, integrated genomic, transcriptomic, and protein analysis

IntroductionAryl Hydrocarbon Receptor Interacting Protein-Like 1 (AIPL1) protein interacts with and restricts NEDD8 ultimate buster-1 (NUB1) protein from entering nucleus. The interferon-induced NUB1 protein causes degradation of neddylated proteins through the ubiquitin proteasome system. The AIPL1 transcripts were down regulated in various cancers compared to adjacent normal tissues. The mechanistic roles of AIPL1 and NUB1 protein in cancer cell cycle regulation remain unexplored.Material and methodsProtein expression was examined by immunoblotting and immunochemistry. Cells were cultured in the recommended conditions. The NUB1 monoclonal antibody and the DAKO Envision Plus system were used to evaluate FFPE. Survival curves was analysed by kaplan meier methods and compared by the log rank test. All statistical tests were two sided.Results and discussionsThe meta-analysis of cancer dataset showed the transcripts expression of AIPL1 were down regulated in lung, pancreatic and breast cancer in relative to the adjacent normal tissues. The upregulated NUB1 transcripts were observed in the breast cancer. METABRIC cohort highlighted that patients with low NUB1 transcripts had a poorer survival in the ER-negative subgroup of breast cancer patients [hazard ratio (HR)=0.66, 95% confidence interval (CI)=0.5–0.87, p=0.003] and triple negative subgroup (HR=0.67, 95% CI=0.47–0.96, p=0.028). NUB1 knockdown inhibits in vitro cell growth in MDA-MB-231. AIPL1 protein forms multimers in cancer cells. NUB1 protein moved into the nucleus in hypoxia (0.1% O248 hours). p21 and p27 proteins accumulated in NUB1-knockdown MDA-MB-231 cells. The prolonged G0/G1 cell cycle arrests resulted in cell death through the neddylation-dependent CUL1-p27-p21 and CUL2-VHL axis. We also demonstrated that HIF1α protein could be neddylated upon reoxygenation. In a retrospective study of Oxford breast cancer cohort, the lower cytoplasmic expression (n=57) prognosed worse overall survival than higher cytoplasmic expression (n=57) (HR=1.779, 95% CI=1.006–3.346, p=0.048).ConclusionNUB1 protein depletion cause G0/G1 cell cycle arrest in breast cancer. Low cytoplasmic NUB1 protein prognosed worse survival of breast cancer patients. NUB1 depletion causes cell cycle arrest via the deactivated ubiquitin E3 ligase pathway.

Synthesis and biological evaluation of novel 2-imino-4-thiazolidinone derivatives as potent anti-cancer agents

A new series of 2-imino-4-thiazolidinone derivatives (7a–7t) has been synthesised and screened for their cytotoxicity against three cancer cell lines (B16F10, A549, PANC-1) and normal cell line (CHO). Among the compounds tested, compounds 7k, 7m, 7n showed potent cytotoxicity against B16F10 cell line with IC50 between 3.4 and 7μM. Interestingly these three compounds are non toxic to non cancerous CHO cells and induced apoptosis in B16F10 cells observed by DNA damage analysis through PI/Hoechst double staining method. Compounds 7k and 7n induced G0/G1 cell cycle arrest while compound 7m induced G2/M cell cycle arrest in B16F10 cells which confirms that these compounds have role in cancer cell cycle regulation. Additionally, compound 7m showed generation of intracellular reactive oxygen species (ROS) in B16F10 cells that may contribute in the cell cycle arrest whereas compounds 7k and 7n show anti-cancer activity through independent of ROS formation. Induction of apoptosis, cell cycle arrest in B16F10 cells are found to be the anti-cancer mechanism of these three compounds. The results all together demonstrate the potent cytotoxic nature of these compounds in cancer cells could be considered as new class of chemotherapeutic agents in near future.

Polymer Based Nano-Formulation of Diindolylmethane with High Oral Bioavailability

At the present, a high potential of 3,3’-diindolylmethane (DIM) as a new preventive and therapeutic agent in oncology is well established, due to its ability to target multiple components of cancer cell cycle regulation, survival and progression. However, a very low bioavailability of DIM remains the major challenge for its efficient development as novel medicine. In this work, we have developed a polymer based nano-formulation comprising a non-ionic block copolymer, Pluronic F127 that increases oral bioavailability of DIM by almost one order of magnitude, as compared to the presently marketed products such as crystalline DIM and BioResponse DIM. The pharmacokinetic parameters established in the present study revealed that AUC and Cmax of the new formulation dosed at 60 mg/kg were 7.06 ± 0.93 μg ∙ h/mL, and 3.08 ± 0.17 μg/mL, while in the case of crystalline DIM dosed at the same dose AUC and Cmax were 0.97 ± 0.08 μg ∙ h/mL, and 0.18 ± 0.02 μg/mL. BioResponce DIM showed AUC and Cmax of 1.05 ± 0.05 μg ∙ h/mL, and 0.22 ± 0.02 μg/mL, respectively.

Lin-28 Homologue A (LIN28A) Promotes Cell Cycle Progression via Regulation of Cyclin-dependent Kinase 2 (CDK2), Cyclin D1 (CCND1), and Cell Division Cycle 25 Homolog A (CDC25A) Expression in Cancer

The RNA-binding protein LIN28A regulates the translation and stability of a large number of mRNAs as well as the biogenesis of certain miRNAs in embryonic stem cells and developing tissues. Increasing evidence indicates that LIN28A functions as an oncogene promoting cancer cell growth. However, little is known about its molecular mechanism of cell cycle regulation in cancer. Using tissue microarrays, we found that strong LIN28A expression was reactivated in about 10% (7.1-17.1%) of epithelial tumors (six tumor types, n = 369). Both in vitro and in vivo experiments demonstrate that LIN28A promotes cell cycle progression in cancer cells. Genome-wide RNA-IP-chip experiments indicate that LIN28A binds to thousands of mRNAs, including a large group of cell cycle regulatory mRNAs in cancer and embryonic stem cells. Furthermore, the ability of LIN28A to stimulate translation of LIN28A-binding mRNAs, such as CDK2, was validated in vitro and in vivo. Finally, using a combined gene expression microarray and bioinformatics approach, we found that LIN28A also regulates CCND1 and CDC25A expression and that this is mediated by inhibiting the biogenesis of let-7 miRNA. Taken together, these results demonstrate that LIN28A is reactivated in about 10% of epithelial tumors and promotes cell cycle progression by regulation of both mRNA translation (let-7-independent) and miRNA biogenesis (let-7-dependent).

Cdk11p58 regulation of cell cycle progression in cancer development

Abstract The Cdk11 protein kinases are members of the cyclin-dependent kinase superfamily. There exist two distinct but closely related human CDK11 genes (p110 and p58). Cdk11p58 is a Ser/Thr kinase involved in cell cycle progression, promoting the centrosome maturation; apoptotic signaling and tumorigenesis. Using immunoprecipitation and mass spectrometry approaches we demonstrate that GADD45, PDEF and cdk11p58 interact in a complex that might be involved in cell cycle regulation in cancer. GADD45 protein family members (α, β, and γ) are involved in the induction or prevention of apoptosis, cell cycle arrest and participate in the DNA repair machinery. Arrest at the G2/M phase mediated by GADD45 have been identified to rely on its capacity to inhibit the kinase activities such as the CDK1/cyclinB1 complex and the Aurora A, a serine/threonine kinase that play critical roles in the regulation of mitotic events. PDEF (prostate-derived ETS factor) is a transcriptional factor that plays a major role in cancer development and metastasis. In this study, the kinase activity of cdk11p58 over PDEF as well as the importance of the cdk11p58 binding to the GADD45 family members were evaluated and we demonstate that cdk11p58 phosphorilate PDEF and the phosphorilation process is inhibited by GADD45. Co-expression of PDEF and cdk11p58 in 293T cells leads to PDEF ubiquitination and degradation, which can be reverted by MG132, a proteasome inhibitor. Corroborating this data, confocal microscope analysis revealed that cdk11p58 co-localized with PDEF and ubiquitin into the nucleus. However, the process is partially blockage by the presence of GADD45 gene, which seems to prevent PDEF degradation mediated by cdk11p58. Deregulation of the ETS factors leads to altered expression of key genes required for cancer progression. PDEF acts as a negative regulator of tumor progression by modulating the expression of growth and migration promoting genes. The degradation of PDEF by cdk11p58 may be a critical step in cancer cell tumorigenesis and more experiments are under way to unravel the importance of this event in cancer cell migration and invasion. In order to gain further insights about the role of cdk11p58 and GADD45 in cell cycle regulation of cancer cells, we developed DU145 cell lines overexpressing the GADD45α (DU145-GADD45+) and the cdk11p58 (DU145-p58+) proteins. Additionally, DU145 with the cdk11p58 knocked-down (DU145-p58si) was obtained by transduction of lentivirus containing siRNA against the cdk11p58 gene sequence (Sigma). The biological effect of overexpression or know-down of the cdk11p58 gene in the cell cycle phase was assessed by flow cytometry (FACS) analysis of propidium iodide stained cells. FACS analysis revealed that DU145-p58+ cells progress faster when compared to a control DU145 cell line, while DU145-GADD45+ and DU145-p58si induced cell cycle arrest at the G2/M phase. Furthemore, overexpression of GADD45 in the DU145-p58+ cell line induced an arrest at the G2/M phase, comparable to the control group. Preliminary result of transient transfection of PDEF indicates that ovexpression of PDEF in 293T cells leads to arrest at the G1/S phase. Transient tranfections of cdk11p58 leads to induction of proliferation when compared with control cells while cells expressing the GADD45 α and PDEF genes demonstrate slower proliferation rates. In conclusion, PDEF was identified to be a novel target for the kinase activity of cdk11p58. Cdk11p58 induced cell cycle progression and cell proliferation of a prostate cancer cell line that can be inhibited by GADD45 contributing to cell cycle arrest at the G2/M phase.

Role of Androgen Receptor in Prostate Cancer Cell Cycle Regulation: Interaction with Cell Cycle Regulatory Proteins and Enzymes of DNA Synthesis

The androgen receptor (AR) plays a critical role in proliferation and viability of prostate cancer cells. Therefore, suppressing AR activity by androgen deprivation or anti-androgen treatment has been the frontline therapy for over six decades. However, these treatment strategies are not curative and patients succumb to castration-resistant disease. Although AR is evidently critical for proliferation of prostate cancer cells, very little is known about its mechanism of action in this process. Over the years, the role of AR in prostate cancer cell proliferation and viability has been studied by focusing primarily on its role as a transcription factor. However, recent observations indicate that besides its role as a transcription factor, AR interacts physically with components of the pre-replication complex (pre-RC) and DNA replication machinery (replitase). These interactions may enable AR to exert control over the process of DNA synthesis. In addition, alterations in the proteins that interact with AR in complexes required for DNA synthesis could lead to the development of hormone-refractory prostate cancer. These observations suggest a paradigm shift for the role of AR in proliferation of prostate cancer cells from its role as a transcription factor to a non-transcriptional role as a component of the replication machinery, interacting with cell cycle regulatory proteins and enzymes of DNA synthesis. We propose that a detailed understanding of the structural interactions between AR and the components of pre-RC and replitase may lead to the development of new strategies for the treatment of prostate cancer.

Indole-3-carbinol as a chemopreventive and anti-cancer agent

During the course of oncogenesis and tumor progression, cancer cells constitutively upregulate signaling pathways relevant to cell proliferation and survival as a strategy to overcome genomic instability and acquire resistance phenotype to chemotherapeutic agents. In light of this clinical and molecular heterogeneity of human cancers, it is desirable to concomitantly target these genetic abnormalities by using an agent with pleiotropic mode of action. Indole-3-carbinol and its metabolite 3,3′-diindoylmethane (DIM) target multiple aspects of cancer cell-cycle regulation and survival including Akt-NFκB signaling, caspase activation, cyclin-dependent kinase activities, estrogen metabolism, estrogen receptor signaling, endoplasmic reticulum stress, and BRCA gene expression. This broad spectrum of anti-tumor activities in conjunction with low toxicity underscores the translational value of indole-3-carbinol and its metabolites in cancer prevention/therapy. Furthermore, novel anti-tumor agents with overlapping underlying mechanisms have emerged via structural optimization of indole-3-carbinol and DIM, which may provide considerable therapeutic advantages over the parental compounds with respect to chemical stability and anti-tumor potency. Together, these agents might foster new strategies for cancer prevention and therapy.