Inhibition of cervical cancer cell growth in vitro and in vivo by lentiviral-vector mediated shRNA targeting the common promoter of HPV16 E6 and E7 oncogenes

The Micro-Immunotherapy Medicine 2LPAPI® Displays Immune-Modulatory Effects in a Model of Human Papillomavirus Type-16 L1-Protein Capsid-Treated Human Peripheral Blood Mononuclear Cells and Antiproliferative Effects in a Model of Cervical Cancer Cells

Human papillomavirus (HPV) is the second most common infectious agent causing cancer. Persistent infection with high-risk (HR)-HPV can lead to cervical intra-epithelial neoplasia and cervical carcinomas (CC). While host immune response is necessary for viral clearance, chronic immune activation contributes to a low-grade inflammation that can ultimately lead to carcinogenesis. The micro-immunotherapy medicine (MIM) 2LPAPI® could be a valuable tool to manage the clearance of the virus and reduce the risk of developing CC. In this in vitro study, we aimed to investigate its mode of action. We showed that actives from the MIM increased the IL-6, IFN-γ, and IP-10 secretion in human peripheral blood mononuclear cells (PBMCs) exposed to peptides derived from the HPV-16 capsid (HPV16(L1)). This could reflect an increase in the immune activity toward HPV-16. At the same time, some active substances reduced the lympho-proliferation and the expression of T-cell activation markers. Finally, some of the MIM actives displayed antiproliferative effects in CC-derived HeLa cells under serum-starvation conditions. Altogether, this body of data highlighted for the first time the dual effect of MIM in the framework of HR-HPV infections as a potential (i) immune modulator of HPV16(L1)-treated PBMCs and (ii) antiproliferative agent of HPV-positive CC cells.

Advances in application of CRISPR-Cas13a system

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) and CRISPR-associated (Cas) proteins serve as an adaptive immune system that safeguards prokaryotes and some of the viruses that infect prokaryotes from foreign nucleic acids (such as viruses and plasmids). The genomes of the majority of archaea and about half of all bacteria contain various CRISPR-Cas systems. CRISPR-Cas systems depend on CRISPR RNAs (crRNAs). They act as a navigation system to specifically cut and destroy foreign nucleic acids by recognizing invading foreign nucleic acids and binding Cas proteins. In this review, we provide a brief overview of the evolution and classification of the CRISPR-Cas system, focusing on the functions and applications of the CRISPR-Cas13a system. We describe the CRISPR-Cas13a system and discuss its RNA-directed ribonuclease function. Meanwhile, we briefly introduce the mechanism of action of the CRISPR-Cas13a system and summarize the applications of the CRISPR-Cas13a system in pathogen detection, eukaryotes, agriculture, biosensors, and human gene therapy. We are right understanding of CRISPR-Cas13a has been broadened, and the CRISPR-Cas13a system will be useful for developing new RNA targeting tools. Therefore, understanding the basic details of the structure, function, and biological characterization of CRISPR-Cas13a effector proteins is critical for optimizing RNA targeting tools.

Optimal delivery of RNA interference by viral vectors for cancer therapy

In recent years, there has been a surge in the innovative modification and application of the viral vector-based gene therapy field. Significant and consistent improvements in the engineering, delivery, and safety of viral vectors have set the stage for their application as RNA interference (RNAi) delivery tools. Viral vector-based delivery of RNAi has made remarkable breakthroughs in the treatment of several debilitating diseases and disorders (e.g., neurological diseases); however, their novelty has yet to be fully applied and utilized for the treatment of cancer. This review highlights the most promising and emerging viral vector delivery tools for RNAi therapeutics while discussing the variables limiting their success and suitability for cancer therapy. Specifically, we outline different integrating and non-integrating viral platforms used for gene delivery, currently employed RNAi targets for anti-cancer effect, and various strategies used to optimize the safety and efficacy of these RNAi therapeutics. Most importantly, we provide great insight into what challenges exist in their application as cancer therapeutics and how these challenges can be effectively navigated to advance the field.

The antiviral effects of a MEK1/2 inhibitor promote tumor regression in a preclinical model of human papillomavirus infection-induced tumorigenesis

Human papillomaviruses (HPVs) are a significant public health concern due to their widespread transmission, morbidity, and oncogenic potential. Despite efficacious vaccines, millions of unvaccinated individuals and those with existing infections will develop HPV-related diseases for the next two decades and beyond. The continuing burden of HPV-related diseases is exacerbated by the lack of effective therapies or cures for infections, highlighting the need to identify and develop antivirals. The experimental murine papillomavirus type 1 (MmuPV1) model provides opportunities to study papillomavirus pathogenesis in cutaneous epithelium, the oral cavity, and the anogenital tract. However, to date the MmuPV1 infection model has not been used to demonstrate the effectiveness of potential antivirals. We previously reported that inhibitors of cellular MEK/ERK signaling suppress oncogenic HPV early gene expression in three-dimensional tissue cultures. Herein, we adapted the MmuPV1 infection model to determine whether MEK inhibitors have anti-papillomavirus properties in vivo. We demonstrate that oral delivery of a MEK1/2 inhibitor promotes papilloma regression in immunodeficient mice that otherwise would have developed persistent infections. Quantitative histological analyses reveal that inhibition of MEK/ERK signaling reduces E6/E7 mRNA, MmuPV1 DNA, and L1 protein expression within MmuPV1-induced lesions. These data suggest that MEK1/2 signaling is essential for both early and late MmuPV1 replication events supporting our previous findings with oncogenic HPVs. We also provide evidence that MEK inhibitors protect mice from developing secondary tumors. Thus, our data suggest that MEK inhibitors have potent antiviral and anti-tumor properties in a preclinical mouse model and merit further investigation as papillomavirus antiviral therapies.

Inhibition of Cellular MEK/ERK Signaling Suppresses Murine Papillomavirus Type 1 Replicative Activities and Promotes Tumor Regression

Human papillomaviruses (HPVs) are a significant public health concern due to their widespread transmission, morbidity, and oncogenic potential. Despite efficacious vaccines, millions of unvaccinated individuals and those with existing infections will develop HPV-related diseases for the next two decades. The continuing burden of HPV-related diseases is exacerbated by the lack of effective therapies or cures for most infections, highlighting the need to identify and develop antivirals. The experimental murine papillomavirus type 1 (MmuPV1) model provides opportunities to study papillomavirus pathogenesis in cutaneous epithelium, the oral cavity, and the anogenital tract. However, to date the MmuPV1 infection model has not been used to demonstrate the effectiveness of potential antivirals. We previously reported that inhibitors of cellular MEK/ERK signaling suppress oncogenic HPV early gene expression in vitro . Herein, we adapted the MmuPV1 infection model to determine whether MEK inhibitors have anti-papillomavirus properties in vivo . We demonstrate that oral delivery of a MEK1/2 inhibitor promotes papilloma regression in immunodeficient mice that otherwise would have developed persistent infections. Quantitative histological analyses revealed that inhibition of MEK/ERK signaling reduces E6/E7 mRNAs, MmuPV1 DNA, and L1 protein expression within MmuPV1-induced lesions. These data suggest that MEK1/2 signaling is essential for both early and late MmuPV1 replication events supporting our previous findings with oncogenic HPVs. We also provide evidence that MEK inhibitors protect mice from developing secondary tumors. Thus, our data suggest that MEK inhibitors have potent anti-viral and anti-tumor properties in a preclinical mouse model and merit further investigation as papillomavirus antiviral therapies.

Significance Statement

Persistent human papillomavirus (HPV) infections cause significant morbidity and oncogenic HPV infections can progress to anogenital and oropharyngeal cancers. Despite the availability of effective prophylactic HPV vaccines, millions of unvaccinated individuals, and those currently infected will develop HPV-related diseases over the next two decades and beyond. Thus, it remains critical to identify effective antivirals against papillomaviruses. Using a mouse papillomavirus model of HPV infection, this study reveals that cellular MEK1/2 signaling supports viral tumorigenesis. The MEK1/2 inhibitor, trametinib, demonstrates potent antiviral activities and promotes tumor regression. This work provides insight into the conserved regulation of papillomavirus gene expression by MEK1/2 signaling and reveals this cellular pathway as a promising therapeutic target for the treatment of papillomavirus diseases.

RNA-based gene targeting therapies for human papillomavirus driven cancers

While platinum-based chemotherapy, radiation therapy and or surgery are effective in reducing human papillomavirus (HPV) driven cancer tumours, they have some significant drawbacks, including low specificity for tumour, toxicity, and severe adverse effects. Though current therapies for HPV-driven cancers are effective, severe late toxicity associated with current treatments contributes to the deterioration of patient quality of life. This warrants the need for novel therapies for HPV derived cancers. In this short review, we examined RNA-based therapies targeting the major HPV oncogenes, including short-interfering RNAs (siRNAs) and clustered regularly interspaced short palindromic repeats (CRISPR) as putative treatment modalities. We also explore other potential RNA-based targeting approaches such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and mRNA vaccines as future treatment modalities for HPV cancers. Some of these technologies have already been approved for clinical use for a range of other human diseases but not for HPV cancers. Here we explore the emerging evidence supporting the effectiveness of some of these gene-based therapies for HPV malignancies. In short, the evidence sheds promising light on the feasibility of translating these technologies into a clinically relevant treatment modality for HPV derived cancers and potentially other virally driven human cancers.

MEK/ERK signaling is a critical regulator of high-risk human papillomavirus oncogene expression revealing therapeutic targets for HPV-induced tumors

Intracellular pathogens have evolved to utilize normal cellular processes to complete their replicative cycles. Pathogens that interface with proliferative cell signaling pathways risk infections that can lead to cancers, but the factors that influence malignant outcomes are incompletely understood. Human papillomaviruses (HPVs) predominantly cause benign hyperplasia in stratifying epithelial tissues. However, a subset of carcinogenic or “high-risk” HPV (hr-HPV) genotypes are etiologically linked to nearly 5% of all human cancers. Progression of hr-HPV-induced lesions to malignancies is characterized by increased expression of the E6 and E7 oncogenes and the oncogenic functions of these viral proteins have been widely studied. Yet, the mechanisms that regulate hr-HPV oncogene transcription and suppress their expression in benign lesions remain poorly understood. Here, we demonstrate that EGFR/MEK/ERK signaling, influenced by epithelial contact inhibition and tissue differentiation cues, regulates hr-HPV oncogene expression. Using monolayer cells, epithelial organotypic tissue models, and neoplastic tissue biopsy materials, we show that cell-extrinsic activation of ERK overrides cellular control to promote HPV oncogene expression and the neoplastic phenotype. Our data suggest that HPVs are adapted to use the EGFR/MEK/ERK signaling pathway to regulate their productive replicative cycles. Mechanistic studies show that EGFR/MEK/ERK signaling influences AP-1 transcription factor activity and AP-1 factor knockdown reduces oncogene transcription. Furthermore, pharmacological inhibitors of EGFR, MEK, and ERK signaling quash HPV oncogene expression and the neoplastic phenotype, revealing a potential clinical strategy to suppress uncontrolled cell proliferation, reduce oncogene expression and treat HPV neoplasia.

Human papillomavirus (HPV) infections occur in differentiating squamous epithelium and induce hyperplasia during the viral replicative cycle. Although HPV oncogene expression is necessary to promote cellular proliferation for viral genome amplification in the middle epithelial layers, oncogene levels are thereafter suppressed to permit differentiation-induced late gene expression in the uppermost epithelial cells. Yet, the mechanisms responsible for controlling HPV oncogene expression are not well understood. Here, we demonstrate that EGFR/MEK/ERK signaling, which is subject to the normal cellular cues of contact inhibition and epithelial tissue differentiation, is a critical regulator of hr-HPV oncogene expression. We found that extrinsic activation of ERK overrides cellular control to promote oncogene expression and the neoplastic phenotype. Many epidemiologically defined risk factors activate the EGFR/MEK/ERK pathway, suggesting a common mechanism whereby they may promote HPV persistence and disease progression. Lastly, we show that HPV oncogene transcription and protein expression remain susceptible to MEK/ERK control in early neoplastic tissues and tumor cells and that targeted inhibition of MEK/ERK signaling might be exploited therapeutically for HPV-induced infections and tumors.

HPV-mediated nuclear export of HP1γ drives cervical tumorigenesis by downregulation of p53

E6 oncoprotein derived from high-risk human papillomavirus (HPV) drives the development of cervical cancer through p53 degradation. Because cervical cancer therapies to inactivate HPV or E6 protein are not available, alternative strategies are required. Here, we show that HPV-mediated nuclear export of human heterochromatin protein 1γ (HP1γ) reduces the stability of p53 through UBE2L3-mediated p53 polyubiquitination during cervical cancer progression. In general, HP1 plays a key role in heterochromatin formation and transcription in the nucleus. However, our immunostaining data showed that the majority of HP1γ is localized in the cytoplasm in HPV-mediated cervical cancer. We found that HPV E6 protein drives unusual nuclear export of HP1γ through the interaction between the NES sequence of HP1γ and exportin-1. The mutation of the NES sequence in HP1γ led to nuclear retention of HP1γ and reduced cervical cancer cell growth and tumor generation. We further discovered that HP1γ directly suppresses the expression of UBE2L3 which drives E6-mediated proteasomal degradation of p53 in cervical cancer. Downregulation of UBE2L3 by overexpression of HP1γ suppressed UBE2L3-dependent p53 degradation-promoting apoptosis of cervical cancer cells. Our findings propose a useful strategy to overcome p53 degradation in cervical cancer through the blockage of nuclear export of HP1γ.

In vitro and in vivo growth inhibition of human cervical cancer cells via human papillomavirus E6/E7 mRNAs' cleavage by CRISPR/Cas13a system

Sustained infection of high-risk human papillomavirus (HR-HPVs), especially HPV16 and HPV18, is a major cause of cervical cancer. E6 and E7 oncoproteins, encoded by the HPV genome, are critical for transformation and maintenance of malignant phenotypes of cervical cancer. Here, we used an emerging programmable clustered regularly interspaced short palindromic repeat (CRISPR)/Cas13a system to cleave HPV 16/18 E6/E7 messenger RNAs (mRNAs). The results showed that customized CRISPR/Cas13a system effectively and specifically knocked down HPV 16/18 E6/E7 mRNAs, inducing growth inhibition and apoptosis in HPV16-positive SiHa and HPV18-positive HeLa Cell lines, but not in HPV-negative C33A cell line. Simultaneously, we detected downregulation of E6/E7 oncoproteins and upregulation of tumor suppressor P53 and RB proteins. In addition, we used subcutaneous xenograft tumor growth assays to find that the weight and volume of tumors in the SiHa-16E6CR1 group knocked down by the CRISPR/Cas13a system were significantly lower than those in the SiHa-VECTOR group lacking crRNA. Our study demonstrated that targeting HPV E6/E7 mRNAs by the CRISPR/Cas13a system may be a candidate therapeutic strategy for HPV-related cervical cancer.

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.

Transcriptional Targeting and MicroRNA Regulation of Lentiviral Vectors

Gene expression regulation is the result of complex interactions between transcriptional and post-transcriptional controls, resulting in cell-type-specific gene expression patterns that are determined by the developmental and differentiation stage of pathophysiological conditions. Understanding the complexity of gene expression regulatory networks is fundamental to gene therapy, an approach which has the potential to treat and cure inherited disorders by delivering the correct gene to patient specific cells or tissues by means of both viral and non-viral vectors. Besides the issues of biosafety, in recent years efforts have focused on achieving a robust and sustained transgene expression, which attains a phenotypic correction in several diseases, while avoiding transgene-related adverse effects, such as overexpression-associated cytotoxicity and/or immune responses to the transgene. In this sense, the use of cell-type-specific promoters and microRNA target sequences (miRTs) in gene transfer expression cassettes have allowed for a restricted expression after gene transfer in several studies. This review will focus on the use of transcriptional and post-transcriptional regulation to achieve a highly specific and safe transgene expression, as well as their application in ex vivo and in vivo gene therapeutic approaches.

Nanoparticles Based on Poly (β-Amino Ester) and HPV16-Targeting CRISPR/shRNA as Potential Drugs for HPV16-Related Cervical Malignancy

Persistent high-risk HPV infection is the main cause of cervical cancer. The HPV oncogene E7 plays an important role in HPV carcinogenesis. Currently, HPV vaccines do not offer an effective treatment for women who already present with cervical disease, and recommended periodical cervical screenings are difficult to perform in countries and areas lacking medical resources. Our aim was to develop nanoparticles (NPs) based on poly (β-amino ester) (PBAE) and HPV16 E7-targeting CRISPR/short hairpin RNA (shRNA) to reduce the levels of HPV16 E7 as a preliminary form of a drug to treat HPV infection and its related cervical malignancy. Our NPs showed low toxicity in cells and mouse organs. By reducing the expression of HPV16 E7, our NPs could inhibit the growth of cervical cancer cells and xenograft tumors in nude mice, and they could reverse the malignant cervical epithelium phenotype in HPV16 transgenic mice. The performance of NPs containing shRNA is better than that of NPs containing CRISPR. HPV-targeting NPs consisting of PBAE and CRISPR/shRNA could potentially be developed as drugs to treat HPV infection and HPV-related cervical malignancy.

MCM7 polymorphisms associated with the AML relapse and overall survival

The minichromosome maintenance complex component 7 (MCM7) encodes a member of MCM complex, which plays a critical role in the initiation of gene replication. Due to the importance of MCM complex, MCM7 gene has been regarded as a candidate gene for cancer development. In the present study, seven MCM7 polymorphisms were genotyped in 344 subjects composed of 103 acute myeloid leukemia (AML) patients and 241 normal controls to examine the possible associations between MCM7 polymorphisms and the risk of AML. MCM7 polymorphisms were not associated with the risk of AML (P > 0.05). However, MCM7 polymorphisms were significantly related to the relapse of AML and overall survival. The rs2070215 (N144S) showed a protective effect to the risk of AML relapse (OR = 0.37; P ^corr = 0.02). In haplotype analyses, the ht1 and ht2 showed significant associations with the risk of AML relapse (P ^corr = 0.02-0.03). In addition, rs1534309 showed an association with the overall survival of AML patients. Patients with major homozygote genotype (CC) of rs1534309 showed a higher survival rate than the patients with other genotypes (CG and GG). The results of the present study indicate that MCM7 polymorphisms may be able to predict the prognosis of AML patients.

E6 and E7 gene silencing results in decreased methylation of tumor suppressor genes and induces phenotype transformation of human cervical carcinoma cell lines

In SiHa and CaSki cells, E6 and E7-targeting shRNA specifically and effectively knocked down human papillomavirus (HPV) 16 E6 and E7 at the transcriptional level, reduced the E6 and E7 mRNA levels by more than 80% compared with control cells that expressed a scrambled-sequence shRNA. E6 and E7 repression resulted in down-regulation of DNA methyltransferase mRNA and protein expression, decreased DNA methylation and increased mRNA expression levels of tumor suppressor genes, induced a certain apoptosis and inhibited proliferation in E6 and E7 shRNA-infected SiHa and CaSki cells compared with the uninfected cells. Repression of E6 and E7 oncogenes resulted in restoration of DNA methyltransferase suppressor pathways and induced apoptosis in HPV16-positive cervical carcinoma cell lines. Our findings suggest that the potential carcinogenic mechanism of HPV16 through influencing DNA methylation pathway to activate the development of cervical cancer exist, and maybe as a candidate therapeutic strategy for cervical and other HPV-associated cancers.

Cathelicidin PR-39 peptide inhibits hypoxia/reperfusion-induced kidney cell apoptosis by suppression of the endoplasmic reticulum-stress pathway

Ischemia/reperfusion injury (IRI) is a major cause of acute kidney damage, which often occurs in deceased donor kidney transplants. Cathelicidin PR-39 peptide possesses anti-inflammatory and wound repair effects through tissue angiogenesis and anti-apoptosis. This study assessed the role of PR-39 in anti-apoptosis in vitro using a lentiviral vector with a kidney specific promoter (KSP) to drive PR-39 expression. Our data revealed that PR-39 peptide was specifically over-expressed in kidney-derived HK-2 cells, but was scarcely detected in non-kidney tissue-derived cells. PR-39 over-expression had a protective role in the hypoxia/re-oxygenation (H/R) treated cells. The anti-apoptotic activity of PR-39 peptide was mediated by the inhibition of caspase-2, caspase-12 and caspase-3 activity in the endoplasmic reticulum (ER) stress-induced apoptotic pathway. It was also revealed that the anti-apoptotic effect of PR-39 peptide was mediated by an apoptosis-related protein, cellular inhibitor apoptosis protein-2 (c-IAP-2). Taken together, the current data demonstrate that PR-39 expression driven by KSP could prevent kidney damage (apoptosis) from IRI via the ER stress-induced apoptotic pathway.

HPV-16 E6/E7 promotes cell migration and invasion in cervical cancer via regulating cadherin switch in vitro and in vivo

PURPOSE

Cadherin switch, as a key hallmark of epithelial-mesenchymal transition (EMT), is characterized by reduced E-cadherin expression and increased N-cadherin or P-cadherin expression, and has been implicated in many aggressive tumors, but the importance and regulatory mechanism of cadherin switch in cervical cancer have not been investigated. Our study aimed to explore the role of cadherin switch by regulation of HPV-16 E6/E7 in progression and metastasis of cervical cancer.

METHODS

The expressions of E-cadherin and P-cadherin were examined by immunohistochemical staining in 40 cases of high-grade cervical lesions with HPV-16 infection only in which HPV-16 E6 and E7 expression had been detected using qRT-PCR method. Through modulating E6 and E7 expression using HPV-16 E6/E7 promoter-targeting siRNAs or expressed vector in vitro, cell growth, migration, and invasion were separately tested by MTT, wound-healing and transwell invasion assays, as well as the expressions of these cadherins by western blot analyses. Finally, the expressions of these cadherins in cancerous tissues of BALB/c-nu mouse model inoculated with the stable HPV-16 E6/E7 gene silencing Siha and Caski cells were also measured by immunohistochemical staining.

RESULTS

Pearson correlation coefficient analyses showed the strongly inverse correlation of E-cadherin expression and strongly positive correlation of P-cadherin expression with E6/E7 level in 40 cases of high-grade cervical lesions. Furthermore, the modulation of HPV-16 E6/E7 expression remarkably influenced cell proliferation, migration, and invasion, as well as the protein levels of E-cadherin and P-cadherin in cervical cell lines. Finally, the reduction of HPV-16 E6/E7 expression led to up-regulated expression of E-cadherin and down-regulated expression of P-cadherin in BALB/c-nu mouse model in vivo assay.

CONCLUSIONS

Our results unraveled the possibility that HPV-16 E6/E7 could promote cell invasive potential via regulating cadherin switching, and consequently contribute to progression and metastasis of cervical cancer.

Curcumin improves the paclitaxel-induced apoptosis of HPV-positive human cervical cancer cells via the NF-κB-p53-caspase-3 pathway

Paclitaxel, isolated from Taxus brevifolia, is considered to be an efficacious agent against a wide spectrum of human cancers, including human cervical cancer. However, dose-limiting toxicity and high cost limit its clinical application. Curcumin, a nontoxic food additive, has been reported to improve paclitaxel chemotherapy in mouse models of cervical cancer. However, the underlying mechanisms remain unclear. In this study, two human cervical cancer cell lines, CaSki [human papilloma virus (HPV)16-positive] and HeLa (HPV18-positive), were selected in which to investigate the effect of curcumin on the anticancer action of paclitaxel and further clarify the mechanisms. Flow cytometry and MTT analysis demonstrated that curcumin significantly promoted paclitaxel-induced apoptosis and cytotoxicity in the two cervical cell lines compared with that observed with paclitaxel alone (P<0.05). Reverse transcription-polymerase chain reaction indicated that the decline of HPV E6 and E7 gene expression induced by paclitaxel was also assisted by curcumin. The expression levels of p53 protein and cleaved caspase-3 were increased significantly in the curcumin plus paclitaxel-treated HeLa and CaSki cells compared with those in the cells treated with paclitaxel alone (P<0.01). Significant reductions in the levels of phosphorylation of IκBα and the p65-NF-κB subunit in CaSki cells treated with curcumin and paclitaxel were observed compared with those in cells treated with paclitaxel alone (P<0.05). This suggests that the combined effect of curcumin and paclitaxel was associated with the NF-κB-p53-caspase-3 pathway. In conclusion, curcumin has the ability to improve the paclitaxel-induced apoptosis of HPV-positive human cervical cancer cell lines via the NF-κB-p53-caspase-3 pathway. Curcumin in combination with paclitaxel may provide a superior therapeutic effect on human cervical cancer.

Construction and detection of the tissue-specific pINV-HPV16 E6/7 vector

A tissue-specific promoter can control downstream gene expression in tissues or organs. The human involucrin (hINV) promoter (pINV) that contains 2474 bp of hINV upstream sequence is able to regulate tissue-specific gene expression. This tissue specificity may be important for the prevention and treatment of human papilloma virus infections. pINV was cloned by polymerase chain reaction and the human papillomavirus (HPV)16 E6/7 gene was obtained from the cancer tissue samples of patients with cervical carcinoma at the Yangzhou Maternal and China Health-Care Center of Jinagsu Province (Yangzhou, China). First, specific primers were designed according to the genomic DNA sequence of the HPV16-type standard strain that has been reported and the E6/7 gene was acquired by PCR. The carcinogenic fraction of the E6/7 gene was removed and the remaining section was cloned into T vectors, sequenced correctly and then cloned into the eukaryotic expression vector pCEP4, which was lacking the CMV promoter. The positive recombinants were identified using blue-white screening and endonuclease digestion, subsequent to sequencing and analysis, and the tissue-specific recombinant pINV-HPV16E6/7 plasmids was detected.

IGF axis and other factors in HPV-related and HPV-unrelated carcinogenesis (review)

The insulin-like growth factor (IGF) axis promotes the growth of cells, tissues and organs. IGF-1 is mainly produced in the liver but is also secreted from local tissues. In the circulation, IGF-1 is bound to insulin-like binding proteins (IGFBPs), and when released it activates the insulin-like growth factor receptor (IGF-1R). The signal is further transmitted by intracellular signaling pathways leading to gene expression that regulates, among others, cell proliferation and survival. This review presents the IGF axis in the context of cell transformation and cancer development. Aspects involving IGF-1 deficiency and protection from cancer are also briefly described. Furthermore, human papillomaviruses (HPVs) interplaying with IGF axis components in cervical cancer development are described. These small dsDNA viruses are divided into low-risk and high-risk HPVs with regard to the potency of their oncogenic actions; they mainly infect epithelial or mucosal cells. Special attention is drawn to expression of two major HPV oncogenes (E6 and E7) initiating and maintaining cervical carcinogenesis, which is a multistep and multifactorial process; therefore, involvement of additional factors such as mitochondrial DNA changes, sex hormones, retinoic and folic acids are also discussed. Finally, IGF axis components and HPV oncogenes as targets in anticancer treatment are presented which include IGF-1R downregulation, RNA interference and anti-HPV therapeutic vaccines. The review concludes that despite an enormous advancement in research on IGF and HPV-related cancers, more molecular studies and clinical trials are needed before commercialized therapies are widely available for oncology patients.

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.