Roscovitine synergizes with conventional chemo-therapeutic drugs to induce efficient apoptosis of human colorectal cancer cells

DPP2/7 is a Potential Predictor of Prognosis and Target in Immunotherapy in Colorectal Cancer: An Integrative Multi-omics Analysis

BACKGROUND

Colorectal cancer (CRC) ranks among the leading causes of cancerrelated deaths.

OBJECTIVE

This study aimed to illuminate the relationship between DPP7 (also known as DPP2) and CRC through a combination of bioinformatics and experimental methodologies.

METHODS

A multi-dimensional bioinformatic analysis on DPP7 was executed, covering its expression, survival implications, clinical associations, functional roles, immune interactions, and drug sensitivities. Experimental validations involved siRNA-mediated DPP7 knockdown and various cellular assays.

RESULTS

Data from the Cancer Genome Atlas (TCGA) identified high DPP7 expression in solid CRC tumors, with elevated levels adversely affecting patient prognosis. A shift from the N0 to the N2 stage in CRC was associated with increased DPP7 expression. Functional insights indicated the involvement of DPP7 in cancer progression, particularly in extracellular matrix disassembly. Immunological analyses showed its association with immunosuppressive entities, and in vitro experiments in CRC cell lines underscored its oncogenic attributes.

CONCLUSION

DPP7 could serve as a CRC prognosis marker, functioning as an oncogene and representing a potential immunotherapeutic target.

Cyclin-dependent kinases as potential targets for colorectal cancer: past, present and future

Colorectal cancer (CRC) is a common cancer in the world and its prevalence is increasing in developing countries. Deregulated cell cycle traverse is a hallmark of malignant transformation and is often observed in CRC as a result of imprecise activity of cell cycle regulatory components, viz. cyclins and cyclin-dependent kinases (CDKs). Apart from cell cycle regulation, some CDKs also regulate processes such as transcription and have also been shown to be involved in colorectal carcinogenesis. This article aims to review cyclin-dependent kinases as potential targets for CRC. Furthermore, therapeutic candidates to target CDKs are also discussed.

Cyclin-Dependent Kinase Inhibitors and Their Therapeutic Potential in Colorectal Cancer Treatment

Cyclin-dependent kinases (CDKs) are key players in cell cycle regulation. So far, more than ten CDKs have been described. Their direct interaction with cyclins allow progression through G1 phase, transitions to S and G2 phase and finally through mitosis (M). While CDK activation is important in cell renewal, its aberrant expression can lead to the development of malignant tumor cells. Dysregulations in CDK pathways are often encountered in various types of cancer, including all gastrointestinal (GI) tract tumors. This prompted the development of CDK inhibitors as novel therapies for cancer. Currently, CDK inhibitors such as CDK4/6 inhibitors are used in pre-clinical studies for cancer treatment. In this review, we will focus on the therapeutic role of various CDK inhibitors in colorectal cancer, with a special focus on the CDK4/6 inhibitors.

Roscovitine and Trichostatin A promote DNA damage repair during porcine oocyte maturation

Faithful repair of DNA double-strand breaks in mammalian oocytes is essential for meiotic maturation and embryonic development. In the present study we investigated the roles of Roscovitine and Trichostatin A (TSA) in DNA damage recovery during invitro maturation of porcine oocytes. Etoposide was used to trigger DNA damage in oocytes. When these DNA-damaged oocytes were treated with 2μM Roscovitine, 50nM TSA or both for 22h, first polar body extrusion and blastocyst formation in all treated groups were significantly improved compared with the etoposide-only group. The most significant improvement was observed when Roscovitine was present. Further immunofluorescent analysis of γH2A.X, an indicator of DNA damage, indicated that DNA damage was significantly decreased in all treated groups. This observation was further supported by analysing the relative mRNA abundance of DNA repair-related genes, including meiotic recombination 11 homolog A (MRE11A), breast cancer type 1 susceptibility protein (BRCA1), Recombinant DNA Repair Protein 51 (RAD51), DNA-dependent protein kinase catalytic subunit (PRKDC) and X-ray cross complementing gene 4 (XRCC4). Compared with the etoposide-only group, the experimental group with combined treatment of Roscovitine and TSA showed a significant decrease of all genes at germinal vesicle and MII stages. The Roscovitine-only treatment group revealed a similar tendency. Together, these results suggest that Roscovitine and TSA treatments could increase the capacity of oocytes to recover from DNA damage by enlisting DNA repair processes.

Targeting CDKs with Roscovitine Increases Sensitivity to DNA Damaging Drugs of Human Osteosarcoma Cells

Cyclin-dependent kinase 2 (CDK2) has been reported to be essential for cell proliferation in several human tumours and it has been suggested as an appropriate target to be considered in order to enhance the efficacy of treatment regimens based on the use of DNA damaging drugs. We evaluated the clinical impact of CDK2 overexpression on a series of 21 high-grade osteosarcoma (OS) samples profiled by using cDNA microarrays. We also assessed the in vitro efficacy of the CDKs inhibitor roscovitine in a panel of drug-sensitive and drug-resistant human OS cell lines. OS tumour samples showed an inherent overexpression of CDK2, and high expression levels at diagnosis of this kinase appeared to negatively impact on clinical outcome. CDK2 expression also proved to be relevant for in vitro OS cells growth. These findings indicated CDK2 as a promising candidate therapeutic marker for OS and therefore we assessed the efficacy of the CDKs-inhibitor roscovitine in both drug-sensitive and -resistant OS cell lines. All cell lines resulted to be responsive to roscovitine, which was also able to increase the activity of cisplatin and doxorubicin, the two most active DNA damaging drugs used in OS chemotherapy. Our results indicated that combined treatment with conventional OS chemotherapeutic drugs and roscovitine may represent a new candidate intervention approach, which may be considered to enhance tumour cell sensitivity to DNA damaging drugs.

Novel pyrazolo[3,4-d]pyrimidine with 4-(1H-benzimidazol-2-yl)-phenylamine as broad spectrum anticancer agents: Synthesis, cell based assay, topoisomerase inhibition, DNA intercalation and bovine serum albumin studies

A series of new pyrazolo[3,4-d]pyrimidine possessing 4-(1H-benzimidazol-2-yl)-phenylamine moiety at C4 position and primary as well as secondary amines at C6 position has been designed and synthesized. Their antitumor activities were evaluated against a panel of 60 human cancer cell lines at National Cancer Institute (NCI). Six compounds displayed potent and broad spectrum anticancer activities at 10 μM. Compounds 8, 12, 14 and 17 proved to be the most active and efficacious candidate in this series, with mean GI₅₀ values of 1.30 μM, 1.43 μM, 2.38 μM and 2.18 μM, respectively against several cancer cell lines. Further biological evaluation of these compounds suggested that these compounds induce apoptosis and inhibit human topoisomerase (Topo) IIα as a possible intracellular target. UV-visible and fluorescence studies of these compounds revealed strong interaction with ct-DNA and bovine serum albumin (BSA).

Roscovitine in cancer and other diseases

Roscovitine [CY-202, (R)-Roscovitine, Seliciclib] is a small molecule that inhibits cyclin-dependent kinases (CDKs) through direct competition at the ATP-binding site. It is a broad-range purine inhibitor, which inhibits CDK1, CDK2, CDK5 and CDK7, but is a poor inhibitor for CDK4 and CDK6. Roscovitine is widely used as a biological tool in cell cycle, cancer, apoptosis and neurobiology studies. Moreover, it is currently evaluated as a potential drug to treat cancers, neurodegenerative diseases, inflammation, viral infections, polycystic kidney disease and glomerulonephritis. This review focuses on the use of roscovitine in the disease model as well as clinical model research.

An RNAi-based screen reveals PLK1, CDK1 and NDC80 as potential therapeutic targets in malignant pleural mesothelioma

BACKGROUND

Malignant pleural mesothelioma (MPM) is an aggressive tumour originating in the thoracic mesothelium. Prognosis remains poor with 9- to 12-month median survival, and new targets for treatments are desperately needed.

METHODS

Utilising an RNA interference (RNAi)-based screen of 40 genes overexpressed in tumours, including genes involved in the control of cell cycle, DNA replication and repair, we investigated potential therapeutic targets for MPM. Following in vitro characterisation of the effects of target silencing on MPM cells, candidates were assessed in tumour samples from 154 patients.

RESULTS

Gene knockdown in MPM cell lines identified growth inhibition following knockdown of NDC80, CDK1 and PLK1. Target knockdown induced cell-cycle arrest and increased apoptosis. Using small-molecule inhibitors specific for these three proteins also led to growth inhibition of MPM cell lines, and Roscovitine (inhibitor of CDK1) sensitised cells to cisplatin. Protein expression was also measured in tumour samples, with markedly variable levels of CDK1 and PLK1 noted. PLK1 expression in over 10% of cells correlated significantly with a poor prognosis.

CONCLUSION

These results suggest that RNAi-based screening has utility in identifying new targets for MPM, and that inhibition of NDC80, CDK1 and PLK1 may hold promise for treatment of this disease.

Purvalanol A, olomoucine II and roscovitine inhibit ABCB1 transporter and synergistically potentiate cytotoxic effects of daunorubicin in vitro

Cyclin-dependent kinase inhibitors (CDKi) have high potential applicability in anticancer therapy, but various aspects of their pharmacokinetics, especially their interactions with drug efflux transporters, have not yet been evaluated in detail. Thus, we investigated interactions of five CDKi (purvalanol A, olomoucine II, roscovitine, flavopiridol and SNS-032) with the ABCB1 transporter. Four of the compounds inhibited efflux of two ABCB1 substrates, Hoechst 33342 and daunorubicin, in MDCKII-ABCB1 cells: Olomoucine II most strongly, followed by roscovitine, purvalanol A, and flavopiridol. SNS-032 inhibited ABCB1-mediated efflux of Hoechst 33342 but not daunorubicin. In addition, purvalanol A, SNS-032 and flavopiridol lowered the stimulated ATPase activity in ABCB1 membrane preparations, while olomoucine II and roscovitine not only inhibited the stimulated ATPase but also significantly activated the basal ABCB1 ATPase, suggesting that these two CDKi are ABCB1 substrates. We further revealed that the strongest ABCB1 inhibitors (purvalanol A, olomoucine II and roscovitine) synergistically potentiate the antiproliferative effect of daunorubicin, a commonly used anticancer drug and ABCB1 substrate, in MDCKII-ABCB1 cells as well as in human carcinoma HCT-8 and HepG2 cells. We suggest that this pronounced synergism is at least partly caused by (i) CDKi-mediated inhibition of ABCB1 transporter leading to increased intracellular retention of daunorubicin and (ii) native cytotoxic activity of the CDKi. Our results indicate that co-administration of the tested CDKi with anticancer drugs that are ABCB1 substrates may allow significant dose reduction in the treatment of ABCB1-expressing tumors.

Inhibition of polyamine oxidase prevented cyclin-dependent kinase inhibitor-induced apoptosis in HCT 116 colon carcinoma cells

Roscovitine and purvalanol are novel cyclin-dependent kinase (CDK) inhibitors that prevent cell proliferation and induce apoptotic cell death in various cancer cell lines. Although a number of studies have demonstrated the potential apoptotic role of roscovitine, there is limited data about the therapeutic efficiency of purvalanol on cancer cells. The natural polyamines (PAs) putrescine, spermidine, and spermine have essential roles in the regulation of cell differentiation, growth, and proliferation, and increased levels of these compounds have been associated with cancer progression. Recently, depletion of intracellular PA levels because of modulation of PA catabolic enzymes was shown to be an indicator of the efficacy of chemotherapeutic agents. In this study, our aim was to investigate the potential role of PA catabolic enzymes in CDK inhibitor-induced apoptosis in HCT 116 colon carcinoma cells. Exposure of cells to roscovitine or purvalanol decreased cell viability in a dose- and time-dependent manner. The selected concentrations of roscovitine and purvalanol inhibited cell viability by 50 % compared with control cells and induced apoptosis by activating the mitochondria-mediated pathway in a caspase-dependent manner. However, the apoptotic effect of purvalanol was stronger than that of roscovitine in HCT 116 cells. In addition, we found that CDK inhibitors decreased PA levels and significantly upregulated expression of key PA catabolic enzymes such as polyamine oxidase (PAO) and spermine oxidase (SMO). MDL-72,527, a specific inhibitor of PAO and SMO, decreased apoptotic potential of CDK inhibitors on HCT 116 cells. Moreover, transient silencing of PAO was also reduced prevented CDK inhibitor-induced apoptosis in HCT 116 cells. We conclude that the PA catabolic pathway, especially PAO, is a critical target for understanding the molecular mechanism of CDK inhibitor-induced apoptosis.

Syringic acid from Tamarix aucheriana possesses antimitogenic and chemo-sensitizing activities in human colorectal cancer cells

CONTEXT

For its variety of biological activities, Tamarix aucheriana (Decne.) Baum. (Tamaricaceae) has an extensive history as a traditional Arab medicine.

OBJECTIVES

Antimitogenic and chemo-sensitizing activities of syringic acid (SA) were studied against human colorectal cancer.

MATERIALS AND METHODS

Chromatographic and spectral data were used for the isolation and identification of SA. MTT, flow cytometry, in vitro invasion and angiogenesis assays, fluoremetry, ELISA and Real Time qPCR were used to test antimitogenic and chemo-sensitizing activities of SA, cell cycle, apoptosis, proteasome and NFκB-DNA-binding activities, cancer cell invasion and angiogenesis, and expression of cell cycle/apoptosis-related genes.

RESULTS

SA showed a time- and dose-dependent (IC₅₀ = 0.95-1.2 mg mL⁻¹) antimitogenic effect against cancer cells with little cytotoxicity on normal fibroblasts (≤20%). SA-altered cell cycle (S/G2-M or G1/G2-M phases) in a time-dependent manner, induced apoptosis, inhibited DNA-binding activity of NFκB (p ≤ 0.0001), chymotrypsin-like/PGPH (peptidyl-glutamyl peptide-hydrolyzing) (p ≤ 0.0001) and the trypsin-like (p ≤ 0.002) activities of 26S proteasome and angiogenesis. SA also differentially sensitized cancer cells to standard chemotherapies with a marked increase in their sensitivity to camptothecin (500-fold), 5FU (20,000-fold), doxorubicin (210-fold), taxol (3134-fold), vinblastine (1000-fold), vincristine (130-fold) and amsacrine (107-fold) compared to standard drugs alone.

DISCUSSION

SA exerted its chemotherapeutic and chemo-sensitizing effects through an array of mechanisms including cell-cycle arrest, apoptosis induction, inhibition of cell proliferation, cell migration, angiogenesis, NFκB DNA-binding and proteasome activities.

CONCLUSION

These results demonstrate the potential of SA as an antimitogenic and chemo-sensitizing agent for human colorectal cancer.

Enhancement of carboplatin- and quercetin-induced cell death by roscovitine is Akt dependent and p53 independent in hepatoma cells

PURPOSE

Hepatocellular carcinoma (HCC) is a common malignancy worldwide and has an annual occurrence of one million new cases. Novel therapeutic strategies of increased efficacy in the treatment of HCC-bearing patients would certainly be helpful. Hence, the authors explored the effect of combination treatment of roscovitine with chemotherapeutic drugs or quercetin (Qctn) in hepatoma cells, HepG2 and Hep3B.

METHODS

Cell viability was assessed by MTT assay, cell growth assay, and nuclear morphological changes by DAPI staining. The altered expression of signaling proteins and apoptotic molecules was established by Western blotting.

RESULTS

Roscovitine pretreatment considerably enhanced the drugs and Qctn-induced cell death in HepG2 and Hep3B cells. The exploratory studies revealed that augmented cell killing in HepG2 and Hep3B was mediated via Akt pathway and was independent of p53. pAkt was found to be significantly downregulated in combination treatment of roscovitine with carboplatin or Qctn. Corresponding to reduced expression of pAkt, the downstream molecules Bcl-2 and proactive forms of caspase 9 and caspase 3 were also downregulated indicating apoptosis.

CONCLUSIONS

The present study reports for the first time, in hepatoma cells, the potentiation of carboplatin- and Qctn-induced cell death by the cell cycle inhibitor roscovitine. Roscovitine can thus be considered as a potential therapeutic target in combination with chemotherapeutic drugs or Qctn for treatment of HCC.

Antiapoptotic effects of roscovitine on camptothecin-induced DNA damage in neuroblastoma cells

In the present study dopaminergic neuroblastoma B65 cells were exposed to Camptothecin (CPT) (0.5-10 μM), either alone or in the presence of roscovitine (ROSC). The results show that CPT induces apoptosis through the activation of ataxia telangiectasia mutated (ATM)-induced cell-cycle alteration in neuroblastoma B65 cells. The apoptotic process is mediated through the activation of cystein proteases, namely calpain/caspases. However, whereas a pan-caspase inhibitor, zVADfmk, inhibited CPT-mediated apoptosis, a calpain inhibitor, calpeptin, did not prevent cell death. Interestingly, CPT also induces CDK5 activation and ROSC (25 μM) blocked CDK5, ATM activation and apoptosis (as measured by caspase-3 activation). By contrast, selective inhibition of ATM, by KU55933, and non-selective inhibition, by caffeine, did not prevent CPT-mediated apoptosis. Thus, we conclude that CDK5 is activated in response to DNA damage and that CDK5 inhibition prevents ATM and p53ser15 activation. However, pharmacological inhibition of ATM using KU55933 and caffeine suggests that ATM inhibition by ROSC is not the only mechanism that might explain the anti-apoptotic effects of this drug in this apoptosis model. Our findings have a potential clinical implication, suggesting that combinatory drugs in the treatment of cancer activation should be administered with caution.