Evaluation of expression of apoptosis-related proteins and their correlation with HPV, telomerase activity, and apoptotic index in cervical cancer

MicroRNAs in HPV associated cancers: small players with big consequences

INTRODUCTION

MicroRNAs (miRs) are short (~20 nucleotides) non-coding ribonuecleic acids (ncRNAs) known to be involved in cellular processes such as proliferation, differentiation, immune response, pathogenicity and tumourigenesis, among many others. The regulatory mechanisms exerted by miRs have been implicated in many cancers, including Human Papillomavirus (HPV)-associated cancers. Areas covered: In this review, the authors discuss the involvement of miRs (-143, -375, -21, -200, -296 etc.) that have been shown to be dysregulated in HPV-associated cancers. This review also encompasses both intracellular and exosomal miRs, and their potential as diagnostic biomarkers in saliva and blood. The authors have also attempted to dissect the functional impact of miRs on cellular processes such as changes in cellular polarity, loss of apoptosis and tumour suppression, and unchecked and uncontrolled cell cycle regulation, all of which ultimately lead to aberrant cellular proliferation. Expert commentary: Identification of dysregulated miRs in HPV-associated cancers opens up new opportunities to develop diagnostic, therapeutic and prognostic biomarkers. Studies on global expression patterns of miRs dysregulated in HPV-associated cancers can be instrumental in developing broader therapeutic strategies. Therapies like anti-miR, miR-replacement and those based on alternative natural products targeting miRs, need to be improved and better synchronized to be cost-effective and have better treatment outcomes.

Survivin, a molecular target for therapeutic interventions in squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most common cancer worldwide. The treatment of locally advanced disease generally requires various combinations of radiotherapy, surgery, and systemic therapy. Despite aggressive multimodal treatment, most of the patients relapse. Identification of molecules that sustain cancer cell growth and survival has made molecular targeting a feasible therapeutic strategy. Survivin is a member of the Inhibitor of Apoptosis Protein (IAP) family, which is overexpressed in most of the malignancies including SCC and totally absent in most of the normal tissues. This feature makes survivin an ideal target for cancer therapy. It orchestrates several important mechanisms to support cancer cell survival including inhibition of apoptosis and regulation of cell division. Overexpression of survivin in tumors is also associated with poor prognosis, aggressive tumor behavior, resistance to therapy, and high tumor recurrence. Various strategies have been developed to target survivin expression in cancer cells, and their effects on apoptosis induction and tumor growth attenuation have been demonstrated. In this review, we discuss recent advances in therapeutic potential of survivin in cancer treatment.

Clinicopathological significance of survivin expression in patients with cervical cancer: A systematic meta-analysis

BACKGROUND

Survivin has been shown to play an important role in cancer pathogenesis. However, its role in cervical cancer development is still controversial. This study was performed to evaluate the clinical significance of survivin expression in cervical cancer.

METHODS

Search of some online electronic databases was conducted to identify available studies. The pooled odds ratios (ORs) with its 95% confidence intervals (CIs) were calculated and analyzed.

RESULTS

Finally, 18 eligible studies with 791 cervical cancer patients, 1,013 cervical intraepithelial neoplasia (CIN) lesions, 199 normal cervical tissues, and 95 samples with chronic cervicitis were identified in this analysis. The pooled OR of survivin expression was found to be significantly higher in the samples from cervical cancer than in those from CIN lesions, normal cervical tissues, and chronic cervicitis. When cervical cancer was compared to CIN lesions, the subgroup analysis by ethnicity showed that survivin expression was associated with a risk of cervical cancer in Asians (P < 0.001), but not in Caucasians (P = 0.659). In addition, survivin was significantly more overexpressed in high-grade cervical cancer than in low-grade cervical cancer. Its expression was also more elevated in advanced-stage patients than in early-stage patients, in lymph node metastasis than in lymph node without metastasis, and in squamous cell carcinoma (SCC) than in adenocarcinoma (AC).

CONCLUSIONS

The expression of survivin may play a key role in the carcinogenesis, progression, and metastasis of cervical cancer. However, survivin expression may be involved in the progression of CIN lesions only in the Asian population. Survivin expression is associated with an increased risk of SCC. Additional studies with larger sample sizes are needed in the future to confirm our findings.

Immunohistochemical expression of apoptosis regulators in squamous cell carcinoma of the cervix and their association with human papillomavirus 16/18 subtypes

BACKGROUND

Human papillomavirus (HPV) infection is an important aetiological factor in squamous cell carcinoma (SCC) of the cervix. Limited studies have been focused on the differences between carcinogenesis of SCCs with and without HPV infection.

AIMS

The main goal of this study is to determine the expression of some of the apoptotic pathway regulators, including P53, Bax and Bcl2 in SCCs with and without high risk HPV 16/18 infection.

STUDY DESIGN

Cross sectional study.

METHODS

A total of 42 paraffin-embedded blocks with the histopathological diagnosis of invasive SCC with determined HPV 16/18 status were selected; half of them were HPV positive and the rest were negative. Afterwards, immunohistochemistry stained slides for p53, Bcl2 and Bax were evaluated with H-score, multiplicative and Additive Quick score by two pathologists; in cases of controversy about the results, the mean results were recorded.

RESULTS

Mean results and percentage of expression of our three markers were significantly higher in the HPV 16/18 infected group than in uninfected individuals: Respectively, the mean score for Bcl2, Bax and p53 staining according to H-scoring method was 68.5, 234, 106.4 in the HPV 16/18 infected group and 4.5, 218.8, 5.07 in the uninfected group; and the Multiplicative Quick score was 4, 14.6, 8.2 in the HPV 16/18 infected group and 3, 12.3, 3.5 in the uninfected group.

CONCLUSION

High risk HPVs possibly act in favour of apoptotic pathway inactivation. The significant difference in apoptotic pathway between SCCs with and without high risk HPVs suggests a different early carcinogenesis pathway.

Reduction in cancer risk by selective and nonselective cyclooxygenase-2 (COX-2) inhibitors

We conducted a series of epidemiologic studies to evaluate the chemopreventive effects of aspirin, ibuprofen, and selective cyxlooxygenase-2 (COX-2) inhibitors (coxibs) against cancers of the breast, colon, prostate, and lung. Composite results across all four cancer sites revealed that regular intake of 325 mg aspirin, 200 mg ibuprofen, or standard dosages of coxibs (200 mg celecoxib or 25 mg rofecoxib) produced risk reductions of 49%, 59%, and 64%, respectively. Use of coxibs for at least 2 years was associated with risk reductions of 71%, 70%, 55%, and 60% for breast cancer, colon cancer, prostate cancer and lung cancer, respectively. Effects of ibuprofen were similar to selective coxibs, and slightly stronger than aspirin. These observed effects are consistent with the relative COX-2 selectivity of ibuprofen, coxibs, and aspirin. Acetaminophen, an analgesic without COX-2 activity, had no effect. Overexpression of COX-2 and increased prostaglandin biosynthesis correlates with carcinogenesis and metastasis at most anatomic sites. These results indicate that regular intake of nonselective or selective COX-2 inhibiting agents protects against the development of major forms of cancer.

Epigenetic deregulation of the COX pathway in cancer

Inflammation is a major cause of cancer and may condition its progression. The deregulation of the cyclooxygenase (COX) pathway is implicated in several pathophysiological processes, including inflammation and cancer. Although, its targeting with nonsteroidal antiinflammatory drugs (NSAIDs) and COX-2 selective inhibitors has been investigated for years with promising results at both preventive and therapeutic levels, undesirable side effects and the limited understanding of the regulation and functionalities of the COX pathway compromise a more extensive application of these drugs. Epigenetics is bringing additional levels of complexity to the understanding of basic biological and pathological processes. The deregulation of signaling and biosynthetic pathways by epigenetic mechanisms may account for new molecular targets in cancer therapeutics. Genes of the COX pathway are seldom mutated in neoplastic cells, but a large proportion of them show aberrant expression in different types of cancer. A growing body of evidence indicates that epigenetic alterations play a critical role in the deregulation of the genes of the COX pathway. This review summarizes the current knowledge on the contribution of epigenetic processes to the deregulation of the COX pathway in cancer, getting insights into how these alterations may be relevant for the clinical management of patients.

Activation of telomerase by seminal plasma in malignant and normal cervical epithelial cells

Seminal fluids are involved in the development of cervical cancer but the underlying mechanism is unclear. Because cellular transformation requires telomerase activation by expression of the telomerase reverse transcriptase (hTERT) gene, we examined the role of seminal fluids in telomerase activation. Significantly elevated hTERT mRNA and telomerase activity were observed in cervical cell lines (HeLa, SiHa and Caski) treated with seminal plasma. Normal cervical epithelial cells expressed minimal levels of hTERT mRNA and telomerase activity, and seminal plasma substantially enhanced both expression and activity. The hTERT promoter activity was similarly increased in seminal plasma-treated HeLa cells and this effect was closely correlated with increased Sp1 expression and binding to the hTERT promoter. Cyclooxygenase-2 (COX-2) was simultaneously increased in HeLa cells exposed to seminal plasma, and blockade of COX-2 induction abolished seminal plasma stimulation of the hTERT promoter activity, hTERT expression and telomerase activity. Prostaglandin E2 (PGE2) mimics the effect of seminal plasma, stimulating Sp1 expression, enhancing Sp1 occupancy on the hTERT promoter and promoter activity. Moreover, tumour growth was robustly enhanced when HeLa cells together with seminal plasma were injected into nude-mice. Taken together, seminal plasma stimulates COX-2-PGE2-Sp1-dependent hTERT transcription, which provides insights into the putative mechanism underlying telomerase activation in cervical epithelial and cancer cells.

The HPV-16 E5 protein represses expression of stress pathway genes XBP-1 and COX-2 in genital keratinocytes

The HPV-16 E5 protein resides in membranes of the endoplasmic reticulum (ER) and modulates cell growth and viral replication. In order to help define its biological activities, we analyzed E5-induced changes in human keratinocyte gene expression. Our studies identified the downregulation of spliced XBP-1 transcripts, a key player in the ER stress response, as a biochemical marker of E5 expression. IRE1alpha, the endoribonuclease responsible for XBP-1 RNA splicing, was also downregulated. Furthermore, cDNA microarray analysis revealed the repression of COX-2, another member of the ER stress pathway. In contrast, these genes were not altered either by the low-risk HPV-6b E5, or a C-terminal HPV-16 E5 mutant, in which the histidine and alanine residues (conserved in high-risk HPVs) were replaced with tyrosine and isoleucine (conserved in low-risk HPVs). HPV-16 E5 was also able to lower COX-2 mRNA levels in cells co-expressing E6/E7, suggesting that it might exert similar activity during viral replication. Interestingly, the E6/E7 genes were independently able to lower COX-2 transcripts compared to vector cells, indicating that multiple pathways of COX-2 repression exist. COX-2 downregulation by E5 could be overcome by thapsigargin or tunicamycin treatments, which initiate ER stress via calcium fluxes and abnormal protein glycosylation respectively, making it unlikely that E5 specifically tempers these pathways. Overall, our data indicate that E5 represses the cellular ER stress response and suggest a potential role for E5 during productive HPV infection.

Detection of autoantibodies to survivin in cervical mucus from patients with human papillomavirus-associated cervical cancer and precursor lesions

OBJECTIVES

To investigate the prevalence of mucosal autoantibodies to survivin in patients with human papillomavirus (HPV)-associated cervical cancer and precursor lesions.

METHODS

Cervical mucus from 117 HPV-associated cervical cancer, 102 high-grade squamous intraepithelial lesion (HSIL), 107 low-grade SIL (LSIL), and 80 normal controls were tested by ELISA using either full length recombinant survivin or survivin-derived peptides. Survivin expression in cervical tissue biopsies was studied by Western Blotting.

RESULTS

Cervical mucus from 33 cervical cancer (28.2%), 17 HSIL (16.6%), and 8 LSIL (7.4%) patients reacted with recombinant survivin. The IgA-class antibody response was significantly higher than that observed in the normal controls. The level of mucosal anti-survivin response was associated to the level and intensity of survivin expression in the different lesions. Finally, reactivity against a survivin Nt-derived peptide was found more frequently than reactivity against a Ct-derived peptide.

CONCLUSIONS

IgA-class autoantibodies against survivin are present in a substantial proportion of cervical mucus from patients with HPV-associated cervical cancer, and precursor lesions. Mucosal anti-survivin response is positively associated with the level of survivin expression and the grade of cervical lesion.

Cyclooxygenase-2 (cox-2) and the inflammogenesis of cancer

Cohesive scientific evidence from molecular, animal, and human investigations supports the hypothesis that aberrant induction of COX-2 and up-regulation of the prostaglandin cascade play a significant role in carcinogenesis, and reciprocally, blockade of the process has strong potential for cancer prevention and therapy. Supporting evidence includes the following: [1] expression of constitutive COX-2-catalyzed prostaglandin biosynthesis is induced by most cancer-causing agents including tobacco smoke and its components (polycylic aromatic amines, heterocyclic amines, nitrosamines), essential polyunsaturated fatty acids (unconjugated linoleic acid), mitogens, growth factors, proinflammatory cytokines, microbial agents, tumor promoters, and other epigenetic factors, [2] COX-2 expression is a characteristic feature of all premalignant neoplasms, [3] COX-2 expression is a characteristic feature of all malignant neoplasms, and expression intensifies with stage at detection and cancer progression and metastasis, [4] all essential features of carcinogenesis (mutagenesis, mitogenesis, angiogenesis, reduced apoptosis, metastasis, and immunosuppression) are linked to COX-2-driven prostaglandin (PGE-2) biosynthesis, [5] animal studies show that COX-2 up-regulation (in the absence of genetic mutations) is sufficient to stimulate the transformation of normal cells to invasive cancer and metastatic disease, [6] non-selective COX-2 inhibitors, such as aspirin and ibuprofen, reduce the risk of human cancer and precancerous lesions, and [7] selective COX-2 inhibitors, such as celecoxib, reduce the risk of human cancer and precancerous lesions at all anatomic sites thus far investigated. Results confirming that COX-2 blockade is effective for both cancer prevention and therapy have been tempered by observations that some COX2 inhibitors pose a risk to the cardiovascular system, and more studies are needed in order to determine if certain of these drugs can be taken at dosages that prevent cancer without increasing cardiovascular risk. It is emphasized that the "inflammogenesis model of cancer" is not mutually exclusive and may in fact be synergistic with the accumulation of somatic mutations in tumor suppressor genes and oncogenes or epigenetic factors in the development of cancer.

Survivin protein expression and hypoxia in advanced cervical carcinoma of patients treated by radiotherapy

BACKGROUND

Survivin is strongly overexpressed in the vast majority of cancers. Initial investigations suggest a role for Survivin in radiation resistance. In this study, we investigate the effect of Survivin expression on clinical outcome and its relationship to tumor oxygenation parameters, expression of Hif-1alpha and anemia in patients with advanced cervical cancers treated with radiotherapy.

MATERIAL AND METHODS

Biopsies of 44 patients with cervical cancers (Stage IIB: n=9; Stage IIIB: n=31; Stage IVA: n=4) treated with radiotherapy were assessed by immunochemistry for expression of Survivin. Relation of Survivin to pretreatment tumor oxygenation parameters (HF5, pO(2)), hemoglobin (hb) level, Hif-1alpha expression and clinical parameters were investigated.

RESULTS

Survivin expression was detected in all tumors of the 44 patients. Seven showed a strong expression and 37 have moderate Survivin expression. Patients whose tumors showed moderate Survivin expression had a 5-year overall survival of 66%. However, only one of the seven patients with strong Survivin expression was alive 45 months after treatment. In a Cox regression analysis, Survivin expression was correlated to poor overall survival (p=0.02, RR=3.3). There was no relationship between Survivin expression and pO(2) or HF5, but rather an inverse correlation with hemoglobin level (p=0.04). Furthermore, for six of the seven tumors with a high Survivin expression, Hif-1alpha was detected.

CONCLUSION

Survivin protein expression is linked with anemia and prognosis in advanced cervical carcinoma of patients treated by radiotherapy.

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Expression of the p73 protein in rectal cancers with or without preoperative radiotherapy

PURPOSE

To investigate p73 expression in normal mucosa, primary tumor, and metastasis in relation to radiotherapy (RT) response and clinicopathologic/biologic variables in rectal cancers.

METHODS AND MATERIALS

p73 was immunohistochemically examined on biopsies (unirradiated, n=102), distant (from the large bowel, n=82), and adjacent (adjacent to primary tumor, n=89) normal mucosa samples, primary tumors (n=131), and lymph node metastasis (n=32) from rectal cancer patients participating in a clinical trial of preoperative RT. Seventy-four patients received surgery alone and 57 received additional RT.

RESULTS

Cytoplasmic p73 was increased in the primary tumor compared with the distant or adjacent mucosa (p<or=0.0001). Nuclear (p=0.02) and cytoplasmic (p=0.003) p73 was higher in irradiated distant mucosa samples than in unirradiated ones, and nuclear p73 tended to be increased in irradiated primary tumors compared with unirradiated ones (p=0.06). p73 was positively related to cyclooxygenase-2 expression in irradiated tumors (p=0.03). p73-negative tumors tended to have a lower local recurrence after RT compared with unirradiated cases (p=0.06).

CONCLUSIONS

Normal epithelial cells seem more sensitive to RT than tumor cells regarding p73 expression. Patients with p73-negative rectal tumors may have a lower risk of local recurrence after RT.

Mutations in the mitochondrial DNA D-loop region are frequent in cervical cancer

Background

Mitochondrial DNA (mtDNA) is known for high mutation rates caused by lack of protective histones, inefficient DNA repair systems, and continuous exposure to mutagenic effects of oxygen radicals. Alterations in the non-coding displacement (D) loop of mitochondrial DNA are present in many cancers. It has been suggested that the extent of mitochondrial DNA mutations might be useful in the prognosis of cancer outcome and/or the response to certain therapies. In order to investigate whether a high incidence of mutations exist in mitochondrial DNA of cervical cancer patients, we examined the frequency of mutations in the D-loop region in 19 patients of cervical cancer.

Results

Mutations, often multiple, were detected in 18 of 19 (95%) patients. The presence of mutations correlated with Human Papilloma Virus (HPV) infection in these patients. Mutations were also detected in normal samples and lymphocytes obtained from cervical cancer patients, but their frequency of occurrence was much lower as compared to the cervical cancer tissues.

Conclusion

Our findings indicate that D-loop alterations are frequent in cervical cancers and are possibly caused by HPV infection. There was no association of mtDNA D-loop mutations with the histopathological grade and tumor staging.

γ-Herpesvirus neoplasia: A growing role for COX-2

Both human gamma-herpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) induce neoplasia. Burkitt's and Hodgkin's lymphomas harbor EBV sequences, while KSHV has been associated with Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric castleman's disease (MCD). Each of these gamma-herpesvirus-associated malignancies displays typical characteristics of neoplasia, such as angiogenesis and cell survival. One enzyme commonly overexpressed in breast, prostate, and colon cancers is cyclooxygenase-2 (COX-2). Recently, COX-2 overexpression has been reported in herpesvirus infections in vitro. This review will outline potential mechanisms by which COX-2 may participate in herpesvirus-induced neoplasia.