Association of epigenetic inactivation of the WRN gene with anticancer drug sensitivity in cervical cancer cells

PLK1 phosphorylates WRN at replication forks

Prostate cancer, particularly castration-resistant prostate cancer, remains a serious public health issue. Androgen signaling inhibitors have emerged as a major treatment approach but with limited success. Thus, identification of novel treatment targets is of high clinical relevance. Polo-like kinase 1 (PLK1) has documented roles in various aspects of prostate cancer, including resistance to androgen inhibitors. Radiotherapy is another major approach for treating prostate cancer, but how Plk1 might regulate the efficacy of radiotherapy is unknown. Nonhomologous end joining (NHEJ) and homologous recombination (HR) are 2 major DNA repair pathways, with cellular choices between NHEJ and HR being elegantly regulated by end-processing. However, how the long-range DNA end resection is regulated remains poorly understood. It has been documented that Werner syndrome protein (WRN) is actively involved in the long-range resection pathway. In this study, we demonstrate that PLK1-associated phosphorylation of WRN regulates end resection at double-strand breaks, thereby promoting HR and chromosome stability. Cells expressing the WRN nonphosphorylatable mutant show the phenotype similar to WRN null cells because they lack the ability for long-range resection and increase NHEJ. In summary, we reveal that PLK1-associated Mre11, Rad50 and Nbs1 phosphorylation promotes end resection, eventually affecting cellular choices for double-strand break repair pathways. SIGNIFICANCE STATEMENT: Both DNA damage repair and PLK1 play critical roles in the efficacy of radiotherapy of prostate cancer. The data presented here will provide guidance on how to manipulate PLK1 to improve the efficacy of radiotherapy in clinical settings.

A case of Bloom syndrome manifesting with therapy-related myelodysplastic syndromes harboring a novel BLM gene variant

Bloom syndrome (BS) is an autosomal recessive genetic disorder caused by variants in the BLM gene. BS is characterized by distinct facial features, elongated limbs, and various dermatological complications including photosensitivity, poikiloderma, and telangiectatic erythema. The BLM gene encodes a RecQ helicase critical for genome maintenance, stability, and repair, and a deficiency in functional BLM protein leads to genomic instability and high predisposition to various types of cancers, particularly hematological and gastrointestinal malignancies. Here, we report a case of BS with a previously unreported variant in the BLM gene. The patient was a 34-year-old woman who presented with short stature, prominent facial features, and a history of malignancies, including lymphoma, breast cancer, and myelodysplastic syndromes (MDS). She was initially treated with azacitidine for MDS and showed transient improvement, but eventually died at age of 35 due to progression of MDS. Genetic screening revealed compound heterozygous variants in the BLM gene, with a recurrent variant previously reported in BS in one allele and a previously unreported variant in the other allele. Based on her characteristic clinical features and the presence of heterozygous variants in the BLM gene, she was diagnosed with BS harboring compound heterozygous BLM variants.

Epigenetic modulations in cancer: predictive biomarkers and potential targets for overcoming the resistance to topoisomerase I inhibitors

INTRODUCTION

Altered epigenetic map is frequently observed in cancer and recent investigations have demonstrated a pertinent role of epigenetic modifications in the response to many anticancer drugs including the DNA damaging agents. Topoisomerase I (Top I) is a well-known nuclear enzyme that is critical for DNA function and cell survival and its inhibition causes DNA strand breaks and cell cycle arrest. Inhibitors of human Top I have proven to be a prosperous chemotherapeutic treatment for a vast number of cancer patients. While the treatment is efficacious in many cases, resistance and altered cellular response remain major therapeutic issues.

AREAS COVERED

This review highlights the evidence available till date on the influence of different epigenetic modifications on the response to Top I inhibitors as well as the implications of targeting epigenetic alterations for improving the efficacy and safety of Top I inhibitors.

EXPERT OPINION

The field of epigenetic research is steadily growing. With its assistance, we could gain better understanding on how drug response and resistance work. Epigenetics can evolve as possible biomarkers and predictors of response to many medications including Top I inhibitors, and could have significant clinical implications that necessitate deeper attention.HIGHLIGHTSEpigenetic alterations, including DNA methylation and histone modifications, play a pertinent role in the response to several anticancer treatments, including DNA damaging agents like Top I inhibitors.Although camptothecin derivatives are used clinically as Top I inhibitors for management of cancer, certain types of cancer have inherent and or acquired resistance that limit the curative potential of them.Epigenetic modifications like DNA hypomethylation can either increase or decrease sensitivity to Top I inhibitors by different mechanisms.The combination of Top I inhibitors with the inhibitors of histone modifying enzymes can result in enhanced cytotoxic effects and sensitization of resistant cells to Top I inhibitors.MicroRNAs were found to directly influence the expression of Top I and other proteins in cancer cells resulting in positive or negative alteration of the response to Top I inhibitors.lncRNAs and their genetic polymorphisms have been found to be associated with Top I function and the response to its inhibitors.Clinical trials of epigenetic drugs in combination with Top I inhibitors are plentiful and some of them showed potentially promising outcomes.

RecQ Helicase Somatic Alterations in Cancer

Named the “caretakers” of the genome, RecQ helicases function in several pathways to maintain genomic stability and repair DNA. This highly conserved family of enzymes consist of five different proteins in humans: RECQL1, BLM, WRN, RECQL4, and RECQL5. Biallelic germline mutations in BLM, WRN, and RECQL4 have been linked to rare cancer-predisposing syndromes. Emerging research has also implicated somatic alterations in RecQ helicases in a variety of cancers, including hematological malignancies, breast cancer, osteosarcoma, amongst others. These alterations in RecQ helicases, particularly overexpression, may lead to increased resistance of cancer cells to conventional chemotherapy. Downregulation of these proteins may allow for increased sensitivity to chemotherapy, and, therefore, may be important therapeutic targets. Here we provide a comprehensive review of our current understanding of the role of RecQ DNA helicases in cancer and discuss the potential therapeutic opportunities in targeting these helicases.

Role of DNA Methylation in the Resistance to Therapy in Solid Tumors

Despite the recent advances in chemotherapeutic treatments against cancer, some types of highly aggressive and invasive cancer develop drug resistance against conventional therapies, which continues to be a major problem in the fight against cancer. In recent years, studies of alterations of DNA methylome have given us a better understanding of the role of DNA methylation in the development of tumors. DNA methylation (DNAm) is an epigenetic change that promotes the covalent transfer of methyl groups to DNA. This process suppresses gene expression through the modulation of the transcription machinery access to the chromatin or through the recruitment of methyl binding proteins. DNAm is regulated mainly by DNA methyltransferases. Aberrant DNAm contributes to tumor progression, metastasis, and resistance to current anti-tumoral therapies. Aberrant DNAm may occur through hypermethylation in the promoter regions of tumor suppressor genes, which leads to their silencing, while hypomethylation in the promoter regions of oncogenes can activate them. In this review, we discuss the impact of dysregulated methylation in certain genes, which impact signaling pathways associated with apoptosis avoidance, metastasis, and resistance to therapy. The analysis of methylome has revealed patterns of global methylation, which regulate important signaling pathways involved in therapy resistance in different cancer types, such as breast, colon, and lung cancer, among other solid tumors. This analysis has provided gene-expression signatures of methylated region-specific DNA that can be used to predict the treatment outcome in response to anti-cancer therapy. Additionally, changes in cancer methylome have been associated with the acquisition of drug resistance. We also review treatments with demethylating agents that, in combination with standard therapies, seem to be encouraging, as tumors that are in early stages can be successfully treated. On the other hand, tumors that are in advanced stages can be treated with these combination schemes, which could sensitize tumor cells that are resistant to the therapy. We propose that rational strategies, which combine specific demethylating agents with conventional treatment, may improve overall survival in cancer patients.

WRN inhibits oxidative stress-induced apoptosis of human lensepithelial cells through ATM/p53 signaling pathway and its expression is downregulated by DNA methylation

BACKGROUND

Apoptosis and oxidative stress are the main etiology of age related cataract (ARC). This article aims to investigate the role of WRN in lens epithelial cells (LECs).

METHODS

We estimated the methylation level of WRN in anterior lens capsule tissues of ARC patients. SRA01/04 (LECs) cells were treated with H2O2 or combined with 5-aza-2-deoxycytidine (5-Aza-CdR) or chloroquine. CCK8 and flow cytometry were performed to explore proliferation and apoptosis. The content of ROS was detected by fluorescent probe DCFH-DA. The gene and protein expression was assessed by quantitative real-time PCR or western blot.

RESULTS

WRN was down-regulated and the methylation level of WRN was increased in the anterior lens capsule tissues. WRN overexpression and 5-Aza-CdR enhanced proliferation and repressed apoptosis and oxidative stress of SRA01/04 cells. 5-Aza-CdR enhanced WRN expression. WRN knockdown inhibited proliferation and promoted apoptosis and oxidative stress of SRA01/04 cells, which was rescued by 5-Aza-CdR. WRN overexpression and 5-Aza-CdR repressed ATM/p53 signaling pathway. Furthermore, chloroquine inhibited proliferation and promoted apoptosis and oxidative stress of SRA01/04 cells by activating ATM/p53 signaling pathway. The influence conferred by chloroquine was abolished by WRN overexpression.

CONCLUSION

Our study reveals that DNA methylation mediated WRN inhibits apoptosis and oxidative stress of human LECs through ATM/p53 signaling pathway.

A Phase I Trial of a Guadecitabine (SGI-110) and Irinotecan in Metastatic Colorectal Cancer Patients Previously Exposed to Irinotecan

PURPOSE

Chemotherapeutic resistance eventually develops in all patients with metastatic colorectal cancer (mCRC). Gene silencing through promoter demethylation is one potential reversible mechanism of resistance with administration of hypomethylating agents. We evaluated the safety and tolerability of guadecitabine and irinotecan in patients with mCRC previously treated with irinotecan.

PATIENTS AND METHODS

In this 3+3 dose-escalation study, patients with mCRC previously exposed to irinotecan received guadecitabine days 1 to 5 of a 28-day cycle and irinotecan 125 mg/m2 days 8 and 15 [dose level (DL) 1, guadecitabine 45 mg/m2; DL -1: guadecitabine 30 mg/m2; DL -1G: guadecitabine 30 mg/m2 with growth factor support (GFS); DL 1G: guadecitabine 45 mg/m2 with GFS].

RESULTS

Twenty-two patients were treated across four DLs. Dose-limiting toxicities were neutropenic fever (DL 1 and -1G), biliary drain infection (DL -1), colonic obstruction (DL -1), and severe dehydration (DL 1G). Most common toxicities were neutropenia (82% any grade, 77% Grade 3/4), neutropenic fever (23%), leukopenia (73% any grade, 50% Grade 3/4), and injection site reactions (64% total, 0% Grade 3/4). Patients received a median of 4.5 cycles of treatment; 12/17 evaluable patients had stable disease as best response, with one having initial disease progression but subsequently durable partial response. Circulating tumor DNA showed decrease in global demethylation by LINE-1 after treatment.

CONCLUSIONS

We report the first study of chemo-priming with epigenetic therapy in gastrointestinal cancers. Guadecitabine 45 mg/m2 and irinotecan 125 mg/m2 with GFS was safe and tolerable in patients with mCRC, with early indication of benefit. These data have provided the basis for an ongoing phase II randomized, multicenter trial.

Association of CHFR Promoter Methylation with Treatment Outcomes of Irinotecan-Based Chemotherapy in Metastatic Colorectal Cancer

Aberrant promoter methylation plays a vital role in colorectal carcinogenesis. However, its role in treatment responses is unclear, especially for metastatic disease. Here, we investigated the association between promoter methylation and treatment outcomes of irinotecan-based chemotherapy in 102 patients with metastatic colorectal cancer. Promoter methylation was examined by methylation-specific polymerase chain reaction for three loci (CHFR, WRN, and SULF2) associated with chemotherapy response and five CpG island methylator phenotype (CIMP)–specific markers (CACNA1G, IGF2, NEUROG1, RUNX3, and SOCS1). Association between CHFR methylation and in vitro sensitivity to irinotecan was also evaluated. Promoter methylation of CHFR, WRN, and SULF2 was identified in 16 (15.7%), 24 (23.5%), and 33 (32.4%) patients, respectively. CIMP status was positive in 22 (21.6%) patients. CHFR methylation was associated with a significantly longer time to progression (TTP) (median: 8.77 vs. 4.43 months, P = .019), with trends favoring higher overall survival (OS) (median: 22.83 vs. 20.17 months, P = .300) and response rates (31.3% vs. 17.4%, P = .300). For patients with unmethylated CHFR, TTP (median: 5.60 vs. 3.53, P = .020) and OS (median: 20.57 vs. 9.23, P = .006) were significantly different according to CIMP status. Colorectal cancer cell lines with CHFR methylation demonstrated increased sensitivity to irinotecan. Both CHFR overexpression and combination with 5-aza-2′-deoxycytidine reversed irinotecan sensitivity in CHFR-methylated cell lines, whereas CHFR knockdown in unmethylated cells restored sensitivity to irinotecan. These data suggest that CHFR methylation may be associated with favorable treatment outcomes of irinotecan-based chemotherapy in patients with metastatic colorectal cancer.

Effects of shRNA-mediated silencing of PSMA7 on cell proliferation and vascular endothelial growth factor expression via the ubiquitin-proteasome pathway in cervical cancer

This study aims to evaluate the effects of PSMA7 silencing on cervical cancer (CC) cell proliferation and vascular endothelial growth factor (VEGF) expression through the ubiquitin-proteasome pathway. CC tissues (n = 43) and normal tissues (n = 27) were first collected from patients. Human CC cell line (SiHa) and human normal cervical epithelial cells (H8) were obtained and classified into the normal, blank, negative control (NC), PSMA7-shRNA1, and PSMA7-shRNA2 groups, respectively. In situ hybridization was used to detect the expressions of wild-type and mutant p53 proteins. Immunofluorescence assay was carried out to test the activity of 20S proteasomes. Reverse transcription quantitative polymerase chain reaction and Western blot analysis were both performed to determine the expressions of PSMA7, ubiquitin, P27, P53, and VEGF in sample tissues and cells. 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to analyze cell proliferation rates, and flow cytometry was used to analyze the cell cycle and the apoptotic rate. Compared with normal tissues, CC tissues showed increased expression levels of PSMA7, ubiquitin, p53, VEGF as well as increased activity of 20S proteasomes but exhibited a decrease in p27 expression. Compared with the blank and NC groups, the PSMA7-shRNA1 and PSMA7-shRNA2 groups all had decreased expression levels of PSMA7, ubiquitin, p53, and VEGF as well as decreased cell proliferation, 20S proteasomes activity, and cell number in the S phase, increased p27 expression, cell apoptosis and cell number in the G0/G1 phase. Our study demonstrated that PSMA7 silencing can suppress CC cell proliferation and VEGF expression in addition to promoting cell apoptosis through inhibiting the UPP signaling pathway.

Epigenetic inactivation of tumour suppressor coding and non-coding genes in human cancer: an update

Cancer cells undergo many different alterations during their transformation, including genetic and epigenetic events. The controlled division of healthy cells can be impaired through the downregulation of tumour suppressor genes. Here, we provide an update of the mechanisms in which epigenetically altered coding and non-coding tumour suppressor genes are implicated. We will highlight the importance of epigenetics in the different molecular pathways that lead to enhanced and unlimited capacity of division, genomic instability, metabolic shift, acquisition of mesenchymal features that lead to metastasis, and tumour plasticity. We will briefly describe these pathways, focusing especially on genes whose epigenetic inactivation through DNA methylation has been recently described, as well as on those that are well established as being epigenetically silenced in cancer. A brief perspective of current clinical therapeutic approaches that can revert epigenetic inactivation of non-coding tumour suppressor genes will also be given.

KLF5 promotes cervical cancer proliferation, migration and invasion in a manner partly dependent on TNFRSF11a expression

Although the transcription factor Krüppel-like factor 5 (KLF5) plays important roles in both inflammation and cancer, the mechanism by which this factor promotes cervical carcinogenesis remains unclear. In this study, we demonstrated a potential role for tumour necrosis factor receptor superfamily member 11a (TNFRSF11a), the corresponding gene of which is a direct binding target of KLF5, in tumour cell proliferation and invasiveness. Coexpression of KLF5 and TNFRSF11a correlated significantly with tumorigenesis in cervical tissues (P < 0.05) and manipulation of KLF5 expression positively affected TNFRSF11a mRNA and protein expression. Functionally, KLF5 promoted cancer cell proliferation, migration and invasiveness in a manner dependent partly on TNFRSF11a expression. Moreover, in vivo functional TNFRSF11a-knockdown mouse studies revealed suppression of tumorigenicity and liver metastatic potential. Notably, tumour necrosis factor (TNF)-α induced KLF5 expression by activating the p38 signalling pathway and high KLF5 and TNFRSF11a expression increased the risk of death in patients with cervical squamous cell carcinoma. Our results demonstrate that KLF5 and TNFRSF11a promote cervical cancer cell proliferation, migration and invasiveness.

WRN Promoter CpG Island Hypermethylation Does Not Predict More Favorable Outcomes for Patients with Metastatic Colorectal Cancer Treated with Irinotecan-Based Therapy

PURPOSE

WRN promoter CpG island hypermethylation in colorectal cancer has been reported to increase sensitivity to irinotecan-based therapies. We aimed to characterize methylation of the WRN promoter, determine the effect of WRN promoter hypermethylation upon expression, and validate a previous report that WRN promoter hypermethylation predicts improved outcomes for patients with metastatic colorectal cancer (mCRC) treated with irinotecan-based therapy.

EXPERIMENTAL DESIGN

WRN methylation status was assessed using methylation-specific PCR and bisulfite sequencing assays. WRN expression was determined using qRT-PCR and Western blotting. WRN methylation status was correlated with overall survival (OS) and progression-free survival (PFS) in 183 patients with mCRC. Among these patients, 90 received capecitabine monotherapy as first-line therapy, and 93 received capecitabine plus irinotecan (CAPIRI) therapy as part of the CAIRO phase III clinical trial.

RESULTS

WRN mRNA and WRN protein expression levels were low in colorectal cancer cell lines and in primary colorectal cancer and were largely independent of WRN methylation status. Patients with methylated WRN colorectal cancer had a shorter OS compared with patients who had unmethylated WRN colorectal cancer (HR = 1.6; 95% confidence interval [CI], 1.2-2.2; P = 0.003). Patients with unmethylated WRN showed a significantly longer PFS when treated with CAPIRI compared with capecitabine alone (HR = 0.48; 95% CI, 0.32-0.70; P = 0.0001). In contrast, patients did not benefit from adding irinotecan to capecitabine when WRN was methylated (HR = 1.1; 95% CI, 0.69-1.77; P = 0.7).

CONCLUSIONS

WRN expression is largely independent of WRN promoter hypermethylation in colorectal cancer. Moreover, we could not validate the previous finding that WRN promoter hypermethylation predicts improved clinical outcomes of mCRC treated with irinotecan-based therapy and found instead the opposite result. Clin Cancer Res; 22(18); 4612-22. ©2016 AACR.

Biological implications and therapeutic significance of DNA methylation regulated genes in cervical cancer

Cervical cancer is the second most common cancer among women worldwide. About 528,000 women are diagnosed with cervical cancer contributing to around 266,000 deaths, across the globe every year. Out of these, the burden of 226,000 (85%) deaths occurs in the developing countries, who are less resource intensive to manage the disease. This is despite the fact that cervical cancer is amenable for early detection due to its long and relatively well-known natural history prior to its culmination as invasive disease. Infection with high risk human papillomavirus (hrHPVs) is essential but not sufficient to cause cervical cancer. Although it was thought that genetic mutations alone was sufficient to cause cervical cancer, the current epidemiological and molecular studies have shown that HPV infection along with genetic and epigenetic changes are frequently associated and essential for initiation, development and progression of the disease. Moreover, aberrant DNA methylation in host and HPV genome can be utilized not only as biomarkers for early detection, disease progression, diagnosis and prognosis of cervical cancer but also to design effective therapeutic strategies. In this review, we focus on recent studies on DNA methylation changes in cervical cancer and their potential role as biomarkers for early diagnosis, prognosis and targeted therapy.

Epigenetic Regulation of Werner Syndrome Gene in Age-Related Cataract

Purpose. To examine the promoter methylation and histone modification of WRN (Werner syndrome gene), a DNA repair gene, and their relationship with the gene expression in age-related cataract (ARC) lens. Methods. We collected the lenses after cataract surgery from 117ARC patients and 39 age-matched non-ARC. WRN expression, DNA methylation and histone modification around the CpG island were assessed. The methylation status of Human-lens-epithelium cell (HLEB-3) was chemically altered to observe the relationship between methylation and expression of WRN. Results. The WRN expression was significantly decreased in the ARC anterior lens capsules comparing with the control. The CpG island of WRN promoter in the ARC anterior lens capsules displayed hypermethylation comparing with the controls. The WRN promoter was almost fully methylated in the cortex of ARC and control lens. Acetylated H3 was lower while methylated H3-K9 was higher in ARC anterior lens capsules than that of the controls. The expression of WRN in HLEB-3 increased after demethylation of the cells. Conclusions. A hypermethylation in WRN promoter and altered histone modification in anterior lens capsules might contribute to the ARC mechanism. The data suggest an association of altered DNA repair capability in lens with ARC pathogenesis.

Candidate biomarkers for cervical cancer treatment: Potential for clinical practice (Review)

Cervical cancer ranks high among the causes of female cancer mortalities and is an important disease in developing and developed countries. Current diagnosis of cervical cancer depends on colposcopy, pathological diagnosis and preoperative diagnosis using methods, including magnetic resonance imaging and computed tomography. Advanced cervical cancer has a poor prognosis. The tumor marker squamous cell carcinoma is conventionally used for screening, but recent studies have revealed the mechanisms of carcinogenesis and the factors associated with a poor prognosis in cervical cancer. These include epigenetic biomarkers, with the methylation level of the checkpoint with forkhead and ring finger gene being potentially useful for predicting the malignancy of cervical cancer and sensitivity to treatment with paclitaxel. The extent of methylation of the Werner DNA helicase gene is also useful for determining sensitivity to an anticancer agent, CPT-11. In addition to epigenetic changes, the expression levels of hypoxia-inducible factor 1α subunit, epidermal growth factor receptor and cyclooxygenase-2 have been reported as possible biomarkers in cervical cancer. Novel prognostic factors, including angiogenic factors, fragile histidine triad, thymidylate synthase, glucose-related protein 58 and mucin antigens, have also been described, and hemoglobin and platelets may also be significant prognostic biomarkers. Utilization of these biomarkers may facilitate personalized treatment and improved outcomes in cervical cancer.

Promoter hypermethylation of KLF4 inactivates its tumor suppressor function in cervical carcinogenesis

OBJECTIVE

The KLF4 gene has been shown to be inactivated in cervical carcinogenesis as a tumor suppressor. However, the mechanism of KLF4 silencing in cervical carcinomas has not yet been identified. DNA methylation plays a key role in stable suppression of gene expression.

METHODS

The methylation status of the KLF4 promoter CpG islands was analyzed by bisulfite sequencing (BSQ) in tissues of normal cervix and cervical cancer. KLF4 gene expression was detected by RT-PCR, immunohistochemistry and western blot. KLF4 promoter methylation in cervical cancer cell line was determined by BSQ and methylation-specific polymerase chain reaction (MS-PCR). Cell proliferation ability was detected by cell growth curve and MTT assay.

RESULTS

The methylated allele was found in 41.90% of 24 cervical cancer tissues but only in 11.11% of 11 normal cervix tissues (P<0.005). KLF4 mRNA levels were significantly reduced in cervical cancer tissues compared with normal cervix tissues (P<0.01) and KLF4 mRNA expression showed a significant negative correlation with the promoter hypermethylation (r = -0.486, P = 0.003). Cervical cancer cell lines also showed a significant negative correlation between KLF4 expression and hypermethylation. After treatment with the demethylating agent 5-Azacytidine (5-Aza), the expression of KLF4 in the cervical cancer cell lines at both mRNA and protein levels was drastically increased, the cell proliferation ability was inhibited and the chemosensitivity for cisplatin was significantly increased.

CONCLUSION

KLF4 gene is inactivated by methylation-induced silencing mechanisms in a large subset of cervical carcinomas and KLF4 promoter hypermethylation inactivates the gene's function as a tumor suppressor in cervical carcinogenesis.

Emerging biological treatments for uterine cervical carcinoma

Cervical cancer is the third most common cancer worldwide, and the development of new diagnosis, prognostic, and treatment strategies is a major interest for public health. Cisplatin, in combination with external beam irradiation for locally advanced disease, or as monotherapy for recurrent/metastatic disease, has been the cornerstone of treatment for more than two decades. Other investigated cytotoxic therapies include paclitaxel, ifosfamide and topotecan, as single agents or in combination, revealing unsatisfactory results. In recent years, much effort has been made towards evaluating new drugs and developing innovative therapies to treat cervical cancer. Among the most investigated molecular targets are epidermal growth factor receptor and vascular endothelial growth factor (VEGF) signaling pathways, both playing a critical role in cervical cancer development. Studies with bevacizumab or VEGF receptor tyrosine kinase have given encouraging results in terms of clinical efficacy, without adding significant toxicity. A great number of other molecular agents targeting critical pathways in cervical malignant transformation are being evaluated in preclinical and clinical trials, reporting preliminary promising data.

In the current review, we discuss novel therapeutic strategies which are being investigated for the treatment of advanced cervical cancer.

Discovering new medicines targeting helicases: challenges and recent progress

Helicases are ubiquitous motor proteins that separate and/or rearrange nucleic acid duplexes in reactions fueled by adenosine triphosphate (ATP) hydrolysis. Helicases encoded by bacteria, viruses, and human cells are widely studied targets for new antiviral, antibiotic, and anticancer drugs. This review summarizes the biochemistry of frequently targeted helicases. These proteins include viral enzymes from herpes simplex virus, papillomaviruses, polyomaviruses, coronaviruses, the hepatitis C virus, and various flaviviruses. Bacterial targets examined include DnaB-like and RecBCD-like helicases. The human DEAD-box protein DDX3 is the cellular antiviral target discussed, and cellular anticancer drug targets discussed are the human RecQ-like helicases and eIF4A. We also review assays used for helicase inhibitor discovery and the most promising and common helicase inhibitor chemotypes, such as nucleotide analogues, polyphenyls, metal ion chelators, flavones, polycyclic aromatic polymers, coumarins, and various DNA binding pharmacophores. Also discussed are common complications encountered while searching for potent helicase inhibitors and possible solutions for these problems.