Human papilloma virus 16 E6 RNA interference enhances cisplatin and death receptor-mediated apoptosis in human cervical carcinoma cells

Therapeutic potentials and targeting strategies of quercetin on cancer cells: Challenges and future prospects

BACKGROUND

Every cell in the human body is vital because it maintains equilibrium and carries out a variety of tasks, including growth and development. These activities are carried out by a set of instructions carried by many different genes and organized into DNA. It is well recognized that some lifestyle decisions, like using tobacco, alcohol, UV, or multiple sexual partners, might increase one's risk of developing cancer. The advantages of natural products for any health issue are well known, and researchers are making attempts to separate flavonoid-containing substances from plants. Various parts of plants contain a phenolic compound called flavonoid. Quercetin, which belongs to the class of compounds known as flavones with chromone skeletal structure, has anti-cancer activity.

PURPOSE

The study was aimed at investigating the therapeutic action of the flavonoid quercetin on various cancer cells.

METHODS

The phrases quercetin, anti-cancer, nanoparticles, and cell line were used to search the data using online resources such as PubMed, and Google Scholar. Several critical previous studies have been included.

RESULTS

Quercetin inhibits various dysregulated signaling pathways that cause cancer cells to undergo apoptosis to exercise its anticancer effects. Numerous signaling pathways are impacted by quercetin, such as the Hedgehog system, Akt, NF-κB pathway, downregulated mutant p53, JAK/STAT, G1 phase arrest, Wnt/β-Catenin, and MAPK. There are downsides to quercetin, like hydrophobicity, first-pass effect, instability in the gastrointestinal tract, etc., because of which it is not well-established in the pharmaceutical industry. The solution to these drawbacks in the future is using bio-nanomaterials like chitosan, PLGA, liposomes, and silk fibroin as carriers, which can enhance the target specificity of quercetin. The first section of this review covers the specifics of flavonoids and quercetin; the second section covers the anti-cancer activity of quercetin; and the third section explains the drawbacks and conjugation of quercetin with nanoparticles for drug delivery by overcoming quercetin's drawback.

CONCLUSIONS

Overall, this review presented details about quercetin, which is a plant derivative with a promising molecular mechanism of action. They inhibit cancer by various mechanisms with little or no side effects. It is anticipated that plant-based materials will become increasingly relevant in the treatment of cancer.

HPV upregulates MARCHF8 ubiquitin ligase and inhibits apoptosis by degrading the death receptors in head and neck cancer

The membrane-associated RING-CH-type finger ubiquitin ligase MARCHF8 is a human homolog of the viral ubiquitin ligases Kaposi's sarcoma herpesvirus K3 and K5 that promote host immune evasion. Previous studies have shown that MARCHF8 ubiquitinates several immune receptors, such as the major histocompatibility complex II and CD86. While human papillomavirus (HPV) does not encode any ubiquitin ligase, the viral oncoproteins E6 and E7 are known to regulate host ubiquitin ligases. Here, we report that MARCHF8 expression is upregulated in HPV-positive head and neck cancer (HNC) patients but not in HPV-negative HNC patients compared to normal individuals. The MARCHF8 promoter is highly activated by HPV oncoprotein E6-induced MYC/MAX transcriptional activation. The knockdown of MARCHF8 expression in human HPV-positive HNC cells restores cell surface expression of the tumor necrosis factor receptor superfamily (TNFRSF) death receptors, FAS, TRAIL-R1, and TRAIL-R2, and enhances apoptosis. MARCHF8 protein directly interacts with and ubiquitinates the TNFRSF death receptors. Further, MARCHF8 knockout in mouse oral cancer cells expressing HPV16 E6 and E7 augments cancer cell apoptosis and suppresses tumor growth in vivo. Our findings suggest that HPV inhibits host cell apoptosis by upregulating MARCHF8 and degrading TNFRSF death receptors in HPV-positive HNC cells.

Prediction of the Mechanisms by Which Quercetin Enhances Cisplatin Action in Cervical Cancer: A Network Pharmacology Study and Experimental Validation

Yimucao has been used as an herbal medicine to treat gynecological diseases. Common genes of Yimucao active compounds were investigated using network pharmacology. The components and targets of Yimucao were retrieved from the TCMSP database. Cervical cancer targets were collected from GeneCards, TTD, DisGeNET, and KEGG. Cisplatin-related genes were downloaded from GeneWeaver. The protein-protein interaction (PPI) network was created using the STRING database. A drug-bioactive compound-disease-target network was constructed using Cytoscape. GO and KEGG analyses were performed to investigate common targets of quercetin and cisplatin in cervical cancer. We found that quercetin was the highly bioactive compound in Yimucao. The drug-bioactive compound-disease-target network contained 93 nodes and 261 edges. Drug-related key targets were identified, including EGFR, IL6, CASP3, VEGFA, MYC, CCND1, ERBB2, FOS, PPARG, and CASP8. Core targets were primarily related to the response to metal ions, cellular response to xenobiotic stimulus, and transcription factor complex. The KEGG pathway analysis revealed that quercetin and cisplatin may affect cervical cancer through platinum drug resistance and the p53 and HIF-1 pathways. Furthermore, quercetin combined with cisplatin downregulated the expression of EGFR, MYC, CCND1, and ERBB2 proteins and upregulated CASP8 expression in HeLa and SiHa cells. Functionally, quercetin enhanced cisplatin-induced anticancer activity in cervical cancer cells. Our results indicate that quercetin can be used to overcome cisplatin resistance in cervical cancer cells.

HP1γ Sensitizes Cervical Cancer Cells to Cisplatin through the Suppression of UBE2L3

Cisplatin is the most frequently used agent for chemotherapy against cervical cancer. However, recurrent use of cisplatin induces resistance, representing a major hurdle in the treatment of cervical cancer. Our previous study revealed that HP1γ suppresses UBE2L3, an E2 ubiquitin conjugating enzyme, thereby enhancing the stability of tumor suppressor p53 specifically in cervical cancer cells. As a follow-up study of our previous findings, here we have identified that the pharmacological substances, leptomycin B and doxorubicin, can improve the sensitivity of cervical cancer cells to cisplatin inducing HP1γ-mediated elevation of p53. Leptomycin B, which inhibits the nuclear export of HP1γ, increased cisplatin-dependent apoptosis induction by promoting the activation of p53 signaling. We also found that doxorubicin, which induces the DNA damage response, promotes HP1γ-mediated silencing of UBE2L3 and increases p53 stability. These effects resulted from the nuclear translocation and binding of HP1γ on the UBE2L3 promoter. Doxorubicin sensitized the cisplatin-resistant cervical cancer cells, enhancing their p53 levels and rate of apoptosis when administered together with cisplatin. Our findings reveal a therapeutic strategy to target a specific molecular pathway that contributes to p53 degradation for the treatment of patients with cervical cancer, particularly with cisplatin resistance.

Targeted Gene Delivery Therapies for Cervical Cancer

Despite being largely preventable through early vaccination and screening strategies, cervical cancer is the most common type of gynecological malignancy worldwide and constitutes one of the leading causes of cancer deaths in women. Patients with advanced or recurrent disease have a very poor prognosis; hence, novel therapeutic modalities to improve clinical outcomes in cervical malignancy are needed. In this regard, targeted gene delivery therapy is presented as a promising approach, which leads to the development of multiple strategies focused on different aspects. These range from altered gene restoration, immune system potentiation, and oncolytic virotherapy to the use of nanotechnology and the design of improved and enhanced gene delivery systems, among others. In the present manuscript, we review the current progress made in targeted gene delivery therapy for cervical cancer, the advantages and drawbacks and their clinical application. At present, multiple targeted gene delivery systems have been reported with encouraging preclinical results. However, the translation to humans has not yet shown a significant clinical benefit due principally to the lack of efficient vectors. Real efforts are being made to develop new gene delivery systems, to improve tumor targeting and to minimize toxicity in normal tissues.

MDC1 depletion promotes cisplatin induced cell death in cervical cancer cells

OBJECTIVE

Cisplatin, the most common chemotherapeutic drug for the treatment of advanced stage cervical cancers has limitations in terms of drugs resistance observed in patients partly due to functional DNA damage repair (DDR) processes in the cell. Mediator of DNA damage checkpoint 1 (MDC1) is an important protein in the Ataxia telangiectasia mutated (ATM) mediated double stranded DNA break (DSB) repair pathway. In this regard, we investigated the effect of MDC1 change in expression on the cisplatin sensitivity in cervical cancer cells.

RESULTS

Through modulation of MDC1 expression in the cervical cancer cell lines; Hela, SiHa and Caski, we found that all the three cell lines silenced for MDC1 exhibited higher sensitivity to cisplatin treatment with inefficiency in accumulation of p γH2AX, Ser 139 foci and increased accumulation of pChk2 Thr 68 at the damaged chromatin followed by enhanced apoptosis. Further, we observed the increased p53 Ser 15 phosphorylation in the MDC1 depleted cells. Our studies suggest that MDC1 expression could be a key determinant in cervical cancer prognosis and its depletion in combination with cisplatin has the potential to be explored for the sensitisation of chemo-resistant cervical cancer cells.

Human Papillomavirus E6 and E7: The Cervical Cancer Hallmarks and Targets for Therapy

Human papillomavirus (HPV)-induced cervical cancer is a major health issue among women from the poorly/under-developed sectors of the world. It accounts for a high-mortality rate because of its late diagnosis and poor prognosis. Initial establishment and subsequent progression of this form of cancer are completely dependent on two major oncogenes E6 and E7, which are expressed constitutively leading to tumorigenesis. Thus, manipulation of these genes represents the most successful form of cervical cancer therapy. In the present article, information on structural, functional, and clinical dimensions of E6 and E7 activity has been reviewed. The genome organization and protein structure of E6 and E7 have been discussed followed by their mechanism to establish the six major cancer hallmarks in cervical tissues for tumor propagation. The later section of this review article deals with the different modes of therapeutics, which functions by deregulating E6 and E7 activity. Since E6 and E7 are the biomarkers of a cervical cancer cell and are the ones driving the cancer progression, therapeutic approaches targeting E6 and E7 have been proved to be highly efficient in terms of focused removal of abnormally propagating malignant cells. Therapeutics including different forms of vaccines to advanced genome editing techniques, which suppress E6 and E7 activity, have been found to successfully bring down the population of cervical cancer cells infected with HPV. T-cell mediated immunotherapy is another upcoming successful form of treatment to eradicate HPV-infected tumorigenic cells. Additionally, therapeutics using natural compounds from plants or other natural repositories, i.e., phytotherapeutic approaches have also been reviewed here, which prove their anticancer potential through E6 and E7 inhibitory effects. Thus, E6 and E7 repression through any of these methods is a significant approach toward cervical cancer therapy, described in details in this review along with an insight into the signaling pathways and molecular mechanistic of E6 and E7 action.

FLT3L and granulocyte macrophage colony-stimulating factor enhance the anti-tumor and immune effects of an HPV16 E6/E7 vaccine

HPV16 infections promote the development and progression of cervical cancer. We investigated Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor as new adjuvants to an HPV16 vaccine. C57BL/6 mice were immunized by intramuscular injections of HPV16 E6/E7 plasmids every two weeks, three times in all. An in vivo imaging system was used to observe tumor growth and metastasis. Pathological changes to the heart, liver, spleen, lungs, brain and kidneys were recorded, and the survival rate of the mice was determined. The constructed HPV16 E6/E7 vaccine had no notable side effects in terms of physiological or biochemical indexes. Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor increased the inhibitory effects of the HPV16 E6/E7 vaccine on tumor growth and metastasis in vivo. The HPV16 E6/E7 vaccine enhanced the survival of mice and increased their serum-specific antibody and interferon-γ levels. Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor augmented these effects. In a cytotoxic lymphocyte killing test, Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor improved the ability of splenic lymphocytes from HPV16 E6/E7-vaccinated mice to kill B16 cells. As Fms-like Tyrosine Kinase 3 Ligand and granulocyte macrophage colony-stimulating factor enhanced the anti-tumor and immune effects of the HPV16 vaccine, these adjuvants should be considered for the treatment of cervical cancer.

Single-Domain Antibodies Represent Novel Alternatives to Monoclonal Antibodies as Targeting Agents against the Human Papillomavirus 16 E6 Protein

Approximately one fifth of all malignancies worldwide are etiologically associated with a persistent viral or bacterial infection. Thus, there is a particular interest in therapeutic molecules which use components of a natural immune response to specifically inhibit oncogenic microbial proteins, as it is anticipated they will elicit fewer off-target effects than conventional treatments. This concept has been explored in the context of human papillomavirus 16 (HPV16)-related cancers, through the development of monoclonal antibodies and fragments thereof against the viral E6 oncoprotein. Challenges related to the biology of E6 as well as the functional properties of the antibodies themselves appear to have precluded their clinical translation. Here, we addressed these issues by exploring the utility of the variable domains of camelid heavy-chain-only antibodies (denoted as VHHs). Through construction and panning of two llama, immune VHH phage display libraries, a pool of potential VHHs was isolated. The interactions of these with recombinant E6 were further characterized using an enzyme-linked immunosorbent assay (ELISA), Western blotting under denaturing and native conditions, and surface plasmon resonance. Three VHHs were identified that bound recombinant E6 with nanomolar affinities. Our results lead the way for subsequent studies into the ability of these novel molecules to inhibit HPV16-infected cells in vitro and in vivo.

CP-31398 inhibits the progression of cervical cancer through reversing the epithelial mesenchymal transition via the downregulation of PAX2s

CP-31398, a styrylquinazoline, emerges from a screen for therapeutic agents that restore the wild-type DNA-binding conformation of mutant p53 to suppress tumors in vivo, but its effects on cervical cancer (CC) remain unknown. Hence, this study aimed to explore the effects CP-31398 has on the CC cells and to investigate whether it is associated with paired box 2 (PAX2) expression. CC cells were treated with different concentrations of CP-31398 (1, 2, 4, 6, 8, and 10 μg/ml) to determine the optimum concentration using fluorometric microculture cytotoxicity assay. After constructing the sh-PAX2 vector, CC cells were transfected with sh-PAX2 or treated with CP-31398. The effects of CP-31398 or PAX2 silencing on CC cell proliferation, apoptosis, invasion, and migration were evaluated. Epithelial mesenchymal transition (EMT)-related genes such as E-cadherin, vimentin, N-cadherin, snail, and twist in CC cells were detected. Tumor formation experiment in nude mice was performed to observe tumor growth. The optimum concentration of CP-31398 was 2 μg/ml. PAX2 was overexpressed in CC cells. CC cells treated with CP-31398 or treated with sh-PAX2 inhibited proliferation, invasion, and migration but promoted apoptosis with decreased PAX2 expression. The EMT process in CC cells was also reversed after treatment with CP-31398 or sh-PAX2. Moreover, the tumor formation experiment in nude mice revealed the inhibitory activity of CP-31398 in CC tumor in nude mice by suppressing PAX2. Our results provide evidence that CP-31398 could inhibit EMT and promote apoptosis of CC cells to curb CC tumor growth by downregulating PAX2.

Synthetic siRNA targeting human papillomavirus 16 E6: a perspective on in vitro nanotherapeutic approaches

High-risk human papillomaviruses infect skin and mucosa, causing approximately 5% of cancers worldwide. In the search for targeted nanotherapeutic approaches, siRNAs against the viral E6 transcript have been molecules of interest but have not yet seen successful translation into the clinic. By reviewing the past approximately 15 years of in vitro literature, we identify the need for siRNA validation protocols which concurrently evaluate ranges of key treatment parameters as well as characterize downstream process restoration in a methodical, quantitative manner and demonstrate their implementation using our own data. We also reflect on the future need for more appropriate cell culture models to represent patient lesions as well as the application of personalized approaches to identify optimal treatment strategies.

MiR-23b controls ALDH1A1 expression in cervical cancer stem cells

BACKGROUND

Cancer stem cells has been widely investigated due to its essential role in cancer progression and drug resistance. Here, we try to find a new therapeutic target for cervical cancer stem cells.

METHODS

We detected ALDH1A1-associated miRNAs expression in our isolated tumorspheres and their corresponding parental cells. Sphere formation assay was also used to determine stemness after cells were manipulated with miR-23b plasmid or miR-23b inhibitor.

RESULTS

We found that miR-23b was under-expressed in cervical cancer stem cells to maintain high levels of ALDH1A1. Introduction of miR-23b into cervical cancer cells could alter stemness and cisplatin sensitivity.

CONCLUSIONS

miR-23b plays key role in maintaining stemness of cervical cancer stem cells and can be developed as therapeutic target to better fight against cervical cancer.

Cervical cancer: A comprehensive approach towards extermination

Human Papilloma Virus (HPV) is one of the most common sexually transmitted pathogen, globally. Oncogenic types of HPV are the causative agents of many neoplastic diseases, including cervical cancer, which ranks as the most common cancer affecting females in developing countries. HPV infection of the cervical epithelium and the subsequent integration of viral DNA into the host genome are the major risk factors for cervical cancer. The scientific discovery of HPV as the causal agent of cervical cancer has led to the development of HPV-based diagnostic tools. Prophylactic vaccines, based on the oncogenic HPV type virus-like particles have been introduced in several developed countries as a preliminary preventive approach. Nevertheless, it remains a continuous threat to women in developing countries, where the prophylactic vaccines are unaffordable and organized screening programmes are lacking. This warrants implementation of prevention strategies that will reduce cervical cancer-related mortality. In this review, we have discussed molecular pathogenesis of HPV infection and the risk factors associated with it. The diagnosis, treatment and prevention strategies of HPV-related cervical cancer have also been discussed.

Human papillomavirus confers radiosensitivity in cancer cervix: a hypothesis toward a possible restoration of apoptotic pathways based on clinical outcomes

ABSTRACT 

Aim: To evaluate if high baseline local human papillomavirus (HPV) titer confers radiosensitivity in cancer cervix. A hypothesis is proposed to explain the clinical outcomes. Materials & methods: 121 serial HPV titers from cervical smears of 21 patients were estimated during radiotherapy (RT) and correlated with RT dose–response curves, local response and local disease-free survival (LDFS). Results: Local response (p = 0.04) and LDFS (p = 0.06) were better in high HPV than low HPV baseline group. On multivariate analysis, RT doses for 50% tumor regression and baseline HPV titer were the only predictors for LDFS. Conclusion: Serial reductions of HPV titers following RT could restore the HPV induced temporarily downregulated p53 and pRb apoptotic pathways resulting in radiosensitivity of these tumors.

Bortezomib sensitises TRAIL-resistant HPV-positive head and neck cancer cells to TRAIL through a caspase-dependent, E6-independent mechanism

Human papillomavirus (HPV) is causative for a new and increasing form of head and neck squamous cell carcinomas (HNSCCs). Although localised HPV-positive cancers have a favourable response to radio-chemotherapy (RT/CT), the impact of HPV in advanced or metastatic HNSCC remains to be defined and targeted therapeutics need to be tested for cancers resistant to RT/CT. To this end, we investigated the sensitivity of HPV-positive and -negative HNSCC cell lines to TRAIL (tumour necrosis factor-related apoptosis-inducing ligand), which induces tumour cell-specific apoptosis in various cancer types. A clear correlation was observed between HPV positivity and resistance to TRAIL compared with HPV-negative head and neck cancer cell lines. All TRAIL-resistant HPV-positive cell lines tested were sensitised to TRAIL-induced cell death by treatment with bortezomib, a clinically approved proteasome inhibitor. Bortezomib-mediated sensitisation to TRAIL was associated with enhanced activation of caspase-8, -9 and -3, elevated membrane expression levels of TRAIL-R2, cytochrome c release and G2/M arrest. Knockdown of caspase-8 significantly blocked cell death induced by the combination therapy, whereas the BH3-only protein Bid was not required for induction of apoptosis. XIAP depletion increased the sensitivity of both HPV-positive and -negative cells to TRAIL alone or in combination with bortezomib. In contrast, restoration of p53 following E6 knockdown in HPV-positive cells had no effect on their sensitivity to either single or combination therapy, suggesting a p53-independent pathway for the observed response. In summary, bortezomib-mediated proteasome inhibition sensitises previously resistant HPV-positive HNSCC cells to TRAIL-induced cell death through a mechanism involving both the extrinsic and intrinsic pathways of apoptosis. The cooperative effect of these two targeted anticancer agents therefore represents a promising treatment strategy for RT/CT-resistant HPV-associated head and neck cancers.

HPV16 infection regulates RASSF1A transcription mediated by p53

Human papillomavirus (HPV) 16 infection and RASSF1A expression play important roles in tumor development and progression. However, the precise mechanisms underlying their concerted function in the development of reproductive system tumors still remain to be elucidated. In the present study, we showed that HPV16-E6 selectively upregulates RASSF1A expression via degradation of p53, which interacts with the RASSF1A promoter and regulates apoptosis. Overexpression of p53 triggered a decrease in endogenous RASSF1A in SiHa cells, accompanied by apoptosis. Similarly, knockdown of endogenous HPV16-E6 in SiHa cells with RNA interference (RNAi) led to downregulation of RASSF1A mediated by p53 and the subsequent induction of apoptosis. These findings collectively suggest that HPV16 infection regulates p53-mediated RASSF1A expression and suppresses apoptosis. Moreover, RASSF1A may form an element of the negative autoregulatory feedback loops that act on the HPV16 response and are involved in p53-dependent apoptosis. Our results provide novel insights into the cellular mechanism of tumor development, and present a starting point for the development of novel strategies in cancer treatment and effective diagnosis.

Nip the HPV encoded evil in the cancer bud: HPV reshapes TRAILs and signaling landscapes

HPV encoded proteins can elicit ectopic protein–protein interactions that re-wire signaling pathways, in a mode that promotes malignancy. Moreover, accumulating data related to HPV is now providing compelling substantiation of a central role played by HPV in escaping immunosurveillance and impairment of apoptotic response. What emerges is an intricate network of Wnt, TGF, Notch signaling cascades that forms higher-order ligand–receptor complexes routing downstream signaling in HPV infected cells. These HPV infected cells are regulated both extracellularly by ligand receptor axis and intracellularly by HPV encoded proteins and impair TRAIL mediated apoptosis. We divide this review into different sections addressing how linear signaling pathways integrate to facilitate carcinogenesis and compounds that directly or indirectly reverse these aberrant interactions offer new possibilities for therapy in cancer. Although HPV encoded proteins mediated misrepresentation of pathways is difficult to target, improved drug-discovery platforms and new technologies have facilitated the discovery of agents that can target dysregulated pathways in HPV infected cervical cancer cells, thus setting the stage for preclinical models and clinical trials.

RNA interference for the treatment of papillomavirus disease

Human Papillomavirus (HPV)-induced diseases are a significant burden on our healthcare system and current therapies are not curative. Vaccination provides significant prophylactic protection but effective therapeutic treatments will still be required. RNA interference (RNAi) has great promise in providing highly specific therapies for all HPV diseases yet this promise has not been realised. Here we review the research into RNAi therapy for HPV in vitro and in vivo and examine the various targets and outcomes. We discuss the idea of using RNAi with current treatments and address delivery of RNAi, the major issue holding back clinical adoption. Finally, we present our view of a potential path to the clinic.

Induction of p53, p21 and apoptosis by silencing the NF90/NF45 complex in human papilloma virus-transformed cervical carcinoma cells

The heterodimeric nuclear factor 90/nuclear factor 45 complex (NF90/NF45) binds nucleic acids and is a multifunctional regulator of gene expression. Here we report that depletion of NF90/NF45 restores the expression of the p53 and p21 proteins in cervical carcinoma cells infected with high-risk human papillomaviruses (HPV). Knockdown of either NF90 or NF45 by RNA interference led to greatly elevated levels of p53 and p21 proteins in HPV-derived HeLa and SiHa cells, but not in other cancerous or normal cell lines. In HeLa cells, p21 mRNA increased concomitantly but the level of p53 mRNA was unaffected. RNA interference directed against p53 prevented the induction of both proteins. These results indicated that the up-regulation of p21 is due to p53-dependent transcription, whereas p53 is regulated post-transcriptionally. Proteasome-mediated turnover of p53 is accelerated by the HPV E6 and cellular E6AP proteins. We therefore examined the hypothesis that this pathway is regulated by NF90/NF45. Indeed, depletion of NF90 attenuated the expression of E6 RNA and inhibited transcription from the HPV early promoter, revealing a new role for NF90/NF45 in HPV gene expression. The transcription inhibition was largely independent of the reduction of P-TEFb levels caused by NF90 depletion. Consistent with p53 derepression, NF90/NF45-depleted HeLa cells displayed elevated PARP cleavage and susceptibility to camptothecin-induced apoptosis. We conclude that high-risk strains of HPV utilize the cellular NF90/NF45 complex for viral E6 expression in infected cervical carcinoma cell lines. Interference with NF90/NF45 function could assist in controlling cervical carcinoma.

DNA methylation profiling across the spectrum of HPV-associated anal squamous neoplasia

BACKGROUND

Changes in host tumor genome DNA methylation patterns are among the molecular alterations associated with HPV-related carcinogenesis. However, there is little known about the epigenetic changes associated specifically with the development of anal squamous cell cancer (SCC). We sought to characterize broad methylation profiles across the spectrum of anal squamous neoplasia.

METHODOLOGY/PRINCIPAL FINDINGS

Twenty-nine formalin-fixed paraffin embedded samples from 24 patients were evaluated and included adjacent histologically normal anal mucosa (NM; n = 3), SCC-in situ (SCC-IS; n = 11) and invasive SCC (n = 15). Thirteen women and 11 men with a median age of 44 years (range 26-81) were included in the study. Using the SFP(10) LiPA HPV-typing system, HPV was detected in at least one tissue from all patients with 93% (27/29) being positive for high-risk HPV types and 14 (93%) of 15 invasive SCC tissues testing positive for HPV 16. Bisulfite-modified DNA was interrogated for methylation at 1,505 CpG loci representing 807 genes using the Illumina GoldenGate Methylation Array. When comparing the progression from normal anal mucosa and SCC-IS to invasive SCC, 22 CpG loci representing 20 genes demonstrated significant differential methylation (p<0.01). The majority of differentially methylated gene targets occurred at or close to specific chromosomal locations such as previously described HPV methylation "hotspots" and viral integration sites.

CONCLUSIONS

We have identified a panel of differentially methlylated CpG loci across the spectrum of HPV-associated squamous neoplasia of the anus. To our knowledge, this is the first reported application of large-scale high throughput methylation analysis for the study of anal neoplasia. Our findings support further investigations into the role of host-genome methylation in HPV-associated anal carcinogenesis with implications towards enhanced diagnosis and screening strategies.

Identification of the deleted in split hand/split foot 1 protein as a novel biomarker for human cervical cancer

The morphological detection of early neoplastic transformation leading to cervical cancer remains problematic. In this work, we have identified deleted in split hand/split foot 1 protein (DSS1) as an early biomarker that is specifically upregulated in premalignant and malignant cervical epithelial cells, but is low or undetectable in non-malignant cells. DSS1 mRNA and protein levels are significantly increased in cultured human cervical carcinoma cell lines originating from primary and metastatic tumors. In fact, > 96% of patient tumor tissues were found to have cells with elevated DSS1 when compared with tumor-adjacent normal cells. In histological sections of cervical tissue containing either invasive cervical carcinoma or its precursor lesions, DSS1 was readily detected in the tumor cells. Steady-state DSS1 expression by immortalized cervical cancer cell lines was found to be necessary for maintenance of their transformed phenotype, since stable shRNA-mediated depletion of DSS1 in HeLa cells inhibited their proliferation and colony-forming activity in monolayer cultures and prevented division of these cells in soft agar. When DSS1 levels are reduced using shRNA, the cells ultimately undergo apoptosis via activation of p53 and the p53 downstream targets, and cleavage of apoptosis-associated proteins including CPP32/caspase-3, poly(ADP-ribose)polymerase and DNA-PKcs. In addition, silencing of DSS1 makes cervical cancer cells sensitive to cell death after treatment with cisplatin. We conclude that the DSS1 protein is critically involved in the maintenance of the transformed phenotype in cervical cancer cells, and that it might be a specific, robust and reliable marker for early detection, diagnosis and treatment.

The PEI-introduced CS shell/PMMA core nanoparticle for silencing the expression of E6/E7 oncogenes in human cervical cells

In this study, we examined the potential of cationic nanoparticle - polyethyleneimine-introduced chitosan shell/poly (methyl methacrylate) core nanoparticles (CS-PEI) for siRNA delivery. Initially, DNA delivery was performed to validate the capability of CS-PEI for gene delivery in the human cervical cancer cell line, SiHa. siRNA delivery were subsequently carried out to evaluate the silencing effect on targeted E6 and E7 oncogenes. Physicochemical properties including size, zeta potential and morphology of CS-PEI/DNA and CS-PEI/siRNA complexes, were analyzed. The surface charges and sizes of the complexes were observed at different N/P ratios. The hydrodynamic sizes of the CS-PEI/DNA and CS-PEI/siRNA were approximately 300-400 and 400-500nm, respectively. Complexes were positively charged depending on the amount of added CS-PEI. AFM images revealed the mono-dispersed and spherical shapes of the complexes. Gel retardation assay confirmed that CS-PEI nanoparticles completely formed complexes with DNA and siRNA at a N/P ratio of 1.6. For DNA transfection, CS-PEI provided the highest transfection result. Localization of siRNA delivered through CS-PEI was confirmed by differential interference contrast (DIC) confocal imaging. The silencing effect of siRNA specific to HPV 16 E6/E7 oncogene was examined at 18 and 24h post-transfection. The results demonstrated the capacity of CS-PEI to suppress the expression of HVP oncogenes.