Expression of cyclins, p53, and Ki-67 in cervical squamous cell carcinomas: overexpression of cyclin A is a poor prognostic factor in stage Ib and II disease

Mannose-Modified Liposome Co-Delivery of Human Papillomavirus Type 16 E7 Peptide and CpG Oligodeoxynucleotide Adjuvant Enhances Antitumor Activity Against Established Large TC-1 Grafted Tumors in Mice

Background

Previously, we demonstrated the therapeutic efficacy of a human papillomavirus (HPV) vaccine, including HPV16 E7 peptide and CpG oligodeoxynucleotides (CpG ODN), against small TC-1 grafted tumors. Here, we developed an HPV16 E7 peptide and CpG ODN vaccine delivered using liposomes modified with DC-targeting mannose, Lip E7/CpG, and determined its anti-tumor effects and influence on systemic immune responses and the tumor microenvironment (TME) in a mouse large TC-1 grafted tumor model.

Methods

L-alpha-phosphatidyl choline (SPC), cholesterol (CHOL), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol-2000)] (DSPE-PEG-2000), 1,2-dioleoyl-3-trimethylammonium-propane chloride salt (DOTAP) and Mannose-PEG-DSPE, loaded with HPV16 E7 peptide and CpG ODN, were used to construct the Lip E7/CpG vaccine. The anti-tumor effects and potential mechanism of Lip E7/CpG were assessed by assays of tumor growth inhibition, immune cells, in vivo cytotoxic T lymphocyte (CTL) responses and cytokines, chemokines, CD31, Ki67 and p53 expression in the TME. In addition, toxicity of Lip E7/CpG to major organs was evaluated.

Results

Lip E7/CpG had a diameter of 122.21±8.37 nm and remained stable at 4°C for 7 days. Co-delivery of HPV16 E7 peptide and CpG ODN by liposomes exerted potent anti-tumor effects in large (tumor volume ≥200mm³) TC-1 grafted tumor-bearing mice with inhibition rates of 80% and 78% relative to the control and Free E7/CpG groups, respectively. Vaccination significantly increased numbers of CD4+ and CD8+ T cells, and IFN-γ-producing cells in spleens and tumors and enhanced HPV-specific CTL responses, while reducing numbers of inhibitory cells including myeloid-derived suppressor cells and macrophages. Expression of cytokines and chemokines was altered and formation of tumor blood vessels was reduced in the Lip E7/CpG group, indicating possible modulation of the immunosuppressive TME to promote anti-tumor responses. Lip E7/CpG did not cause morphological changes in major organs.

Conclusion

Lip E7/CpG induced anti-tumor effects by enhancing cellular immunity and improving tumor-associated immunosuppression. Mannose-modified liposomes are the promising vaccine delivery strategy for cancer immunotherapy.

Induction of systemic immune responses and reversion of immunosuppression in the tumor microenvironment by a therapeutic vaccine for cervical cancer

Cervical cancer is the most common malignant tumor of the genital tract in females worldwide. Persistent human papillomavirus (HPV) infection is closely associated with the occurrence of cervical cancer. No licensed therapeutic HPV vaccines for cervical cancer are currently available. In our previous study, we demonstrated that the vaccine containing the HPV16 E7 43-77 peptide and the adjuvant unmethylated cytosine-phosphate-guanosine oligodeoxynucleotide elicited significant prophylactic and therapeutic effects on cervical cancer. In the current study, we comprehensively evaluated the effect of the vaccine on systemic immune responses and the tumor microenvironment (TME) in a mouse model of cervical cancer. The results showed that the administration of the vaccine induced a significant increase in splenic IFN-γ-producing CD4 and CD8 T cells as well as tumor infiltrating CD4 and CD8 T cells. Moreover, marked decreases in splenic MDSCs and Tregs as well as intratumoral MDSCs, Tregs and type 2-polarized tumor-associated macrophages were observed in the vaccine group. The profile of cytokines, chemokines and matrix metalloproteinases (MMPs) in the TME revealed significantly increased expression of IL-2, IL-12, TNF-α, IFN-γ, CCL-20, CXCL-9, CXCL-10 and CXCL-14 and decreased expression of IL-6, IL-10, TGF-β, CCL-2, CCL-3, CCL-5, CXCL-8, MMP-2, MMP-9 and VEGF in the vaccine group. The expression of the cell proliferation indicator Ki67, apoptosis regulatory protein p53 and angiogenesis marker CD31 was significantly decreased in the vaccine group. In conclusion, the vaccine reversed tolerogenic systemic and local TME immunosuppression and induced robust antitumor immune responses, which resulted in the inhibition of established implanted tumors.

p53 increase mitochondrial copy number via up-regulation of mitochondrial transcription factor A in colorectal cancer

In colorectal cancer, no study has been carried out discovering the relationship among p53, mitochondrial transcription factor A (TFAM) expression and change of mitochondrial DNA (mtDNA) copy number. In our study, co-expression of p53 and TFAM was observed in colon adenocarcinoma tissues, paracancerous tissues and 9 colorectal cancer cell lines. Then, a significant linear correlation was established between either p53 or TFAM expression and advanced TNM stage, positive lymph nodes and low 5-year survival rate in patients with colon adenocarcinoma. Additionally, advanced TNM stage, large tumor burden, presence of distant metastasis, and high TFAM expression were significantly related to poor overall 5-years survival. Moreover, alteration of p53 expression could change TFAM expression but TFAM could not influence p53 expression, and p53 could enhance TFAM expression via binding to TFAM promoter. While, both of p53 and TFAM expression could incrase mtDNA copy number in vitro. In conclusions, p53 might incrase mtDNA copy number through its regulation on TFAM expression via TFAMpromoter.

Immature colon carcinoma transcript-1 promotes proliferation of gastric cancer cells

Gastric cancer is the fourth most common malignant tumor and has been considered as one of the leading causes of cancer-related death worldwide. The identification of the molecular mechanism during gastric cancer progression is urgently needed, which will help to develop more effective treatment strategies. As a component of the human mitoribosome, immature colon carcinoma transcript-1 (ICT1) might be involved in tumor formation and progression. However, its biological function and the corresponding mechanism in gastric cancer have been poorly characterized. To study the mechanism of ICT1 in gastric cancer, we first investigated the mRNA levels of ICT1 in human normal and gastric cancer tissues using datasets from the publicly available Oncomine database. The results showed that ICT1 is overexpressed in gastric cancer tissues. Then in order to study the role of ICT1 in gastric cancer, two shRNAs were used to silence ICT1 in MGC80-3 and AGS cells. Functional analysis showed ICT1 knockdown significantly inhibited the proliferation of gastric cancer cells and induced apoptosis. Further, mechanistic study demonstrated that ICT1 silencing induced cell-cycle arrest at G2/M phase via the suppression of cyclin A2 and cyclin B1. In addition, ICT1 silencing also increased cleaved caspase-3 and activated PARP in gastric cancer cells. These findings suggest that ICT1 may play a crucial role in promoting gastric cancer proliferation in vitro.

Sildenafil potentiates the antitumor activity of cisplatin by induction of apoptosis and inhibition of proliferation and angiogenesis

Sildenafil is the first phosphodiesterase-5 inhibitor used for the treatment of erectile dysfunction. However, recent studies have been suggesting an antitumor effect of sildenafil. The current study assessed the aforementioned activity of sildenafil in vivo and in vitro in solid-tumor-bearing mice and in a human cell line MCF-7, respectively. Moreover, we investigated the impact of sildenafil on cisplatin antitumor activity. The solid tumor was induced by inoculation of Ehrlich ascites carcinoma cells in female mice. The tumor-bearing mice were assigned randomly to control (saline), sildenafil (sildenafil 5 mg/kg/d, PO daily for 15 days), cisplatin (cisplatin 7.5 mg/kg, IP once on the 12th day of Ehrlich ascites carcinoma inoculation), and combination therapy (cisplatin and sildenafil) groups. The tumor volume was measured at the end of the treatment period along with the following parameters: angiogenin, vascular endothelial growth factor, tumor necrosis factor-α, Ki-67, caspase-3, DNA-flow cytometry analysis, and histopathological examination. The study results showed that sildenafil has significantly decreased the tumor volume by 30.4%, angiogenin and tumor necrosis factor-α contents, as well as vascular endothelial growth factor expression. Additionally, caspase-3 level significantly increased with sildenafil treatment, whereas Ki-67 expression failed to show any significant changes. Furthermore, the cell cycle analysis revealed that sildenafil was capable of improving the category of tumor activity from moderate to low proliferative. Sildenafil induced necrosis in the tumor. Moreover, the drug of interest showed cytotoxic activity against MCF-7 in vitro as well as potentiated cisplatin antitumor activity in vivo and in vitro. These findings shed light on the antitumor activity of sildenafil and its possible impact on potentiating the antitumor effect of conventional chemotherapeutic agents such as cisplatin. These effects might be related to antiangiogenic, antiproliferative, and apoptotic activities of sildenafil.

The prognostic role of Ki-67/MIB-1 in cervical cancer: a systematic review with meta-analysis

BACKGROUND

A significant relationship has been reported in which Ki-67/MIB-1 expression is correlated with survival in cervical cancer patients. However, the prognostic value of Ki-67/MIB-1 in cervical cancer is still not well understood.

MATERIAL AND METHOD

A meta-analysis was carried out to explore the prognostic value of Ki-67/MIB-1 on overall survival (OS) and/or disease-free survival (DFS) in cervical cancer. The databases of PubMed, ISI Web of Science, EMBASE, Cochrane Central Register of Controlled Trials, ScienceDirect, and Wiley Online Library were used to identify relevant literature.

RESULTS

We included 18 studies covering 1344 patients in the meta-analysis. The effect of Ki-67/MIB-1 on OS for pooled random effects HR estimate was 1.63 (95% confidence intervals (CI) 1.09-2.45; P<0.05). Subgroup analysis by ethnicity suggested that high expression of Ki-67/MIB-1 had association with Asians (1.84, 95% CI 1.04-3.23), but not with Africans (HR=1.53, 95% CI 0.34-6.86) or Europeans (HR=1.29, 95% CI 0.74-2.23). Furthermore, subgroup analysis of diverse treatments revealed no difference in surgery (HR=1.97, 95% CI 0.78-4.99) and radiation therapy (RT) (HR=1.56, 95% CI 0.93-2.63). The pooled HR for DFS was 1.26 (95% CI 0.58-2.73; P>0.05) and the subgroup analysis indicated Ki-67/MIB1 was associated with DFS (HR=3.67, 95% CI 2.65-5.09) in Asians. In the treatment subgroup analysis, no direct value was found among surgery (HR=1.13, 95% CI 0.10-13.53) and RT (HR=1.26, 95% CI 0.71-2.24).

CONCLUSIONS

Our meta-analysis concludes that Ki-67/MIB-1 had a prognostic value for OS in cervical cancer patients. To further evaluate the prognostic role of Ki-67/MIB-1 on DFS, studies with larger numbers of patients are needed to validate our findings.

Clinicopathology significance of p53 and p63 expression in Indonesian cervical squamous cell carcinomas

BACKGROUND

Human papilloma virus infection is associated with genesis and malignant potential of cervical cancer. E6 and E7 oncogens are known to bind to p53 and retinoblastoma gene products, abrogating their functions as tumor suppressors, leading to an abnormal cell cycle machinery. Roles of the p53 homolog p63 have also been postulated, E6 expression leading to TAp63b degradation allowing anchorage independent growth. Molecular studies correlated with clinicopathological factors are important to determine prognosis and treatment strategies, but results have been controversial and need to be clarified.

AIM

To investigate expression of p53 and p63 in cervical squamous cell carcinomas in correlation with age, FIGO staging, morphology, and cancer cell proliferation.

MATERIALS AND METHODS

Expression of p53 and p63 immunohistochemical staining in a total of 56 paraffin-embedded tissues of cervical squamous cell carcinomas from Dr. Sardjito General Hospital Indonesia, was evaluated for correlation with clinicopathological parameters. The Mann-Whitney test was used to compare the percentage of p53 and p63 expression with patient age, FIGO staging and morphology and to compare mean p53 and p63 expression. The Spearman correlation test was applied to correlate p53 and p63 expression with that of Ki-67. A p-value of <0.05 was considered statistically significant.

RESULTS

There were significant associations between p53 expression with age (p=0.019) and FIGO staging (p=0.026), but not with with morphology or Ki-67 expression. There were no links between p63 expression and age, morphology, FIGO staging or Ki-67.

CONCLUSIONS

This study indicated that p53 has a prognostic value in cervical squamous cell carcinomas given the relation with FIGO staging.

Pathogenic role of the eight probably/possibly carcinogenic HPV types 26, 53, 66, 67, 68, 70, 73 and 82 in cervical cancer

Eight HPV types (HPV26, 53, 66, 67, 68, 70, 73 and 82) that are phylogenetically closely related to 12 WHO-defined high-risk (HR) HPV have been rarely but consistently identified as single HPV infections in about 3% of cervical cancer (CxCa) tissues. Due to lack of biological data, these types are referred to as probable/possible (p) HR-HPV. To analyse their biological activity in direct comparison to HR-HPV types, we selected 55 formalin-fixed, paraffin-embedded (FFPE) CxCa tissues harbouring single pHR-HPV infections (2-13 cases per type) and 266 tissues harbouring single HR-HPV (7-40 cases per type) from a worldwide, retrospective, cross-sectional study. Single HPV infection was verified by two genotyping methods. Presence of type-specific spliced E6*I mRNA transcripts and expression of cellular proteins indicative of HPV transformation were assessed in all cases. In 55 CxCa tissues with pHR-HPV, E6*I mRNA expression was 100%; high p16(INK4a) , 98%; low pRb, 96%; low CyD1, 93%; and low p53, 84%. Compared to HPV16 tissues as a reference, individual frequencies of these five markers did not differ significantly, either for any of the eight pHR-HPV and the 11 other HR types individually or for the groups of pHR and HR types without HPV16. We conclude that the eight pHR-HPV types, when present as a single infection in CxCa, are biologically active and affect the same cellular pathways as any of the fully recognized carcinogenic HR-HPV types. Therefore we have provided molecular evidence of carcinogenicity for types currently classified as probably/possibly carcinogenic. Although this evidence is crucial for HPV-type carcinogenicity classification, per se it is not sufficient for inclusion of these HPV types into population-wide primary and secondary prevention programmes. Such decisions have to include careful estimation of effectiveness and cost-benefit analyses.

The integration of HR-HPV increases the expression of cyclins A and E in cytologies with and without low-grade lesions

Background:

Cyclin-A and cyclin-E are regulators of G1–S phase of normal cell cycle. Integration of human papilloma virus high-risk (HR-HPV) could alter this mechanism, and its overexpression has been associated with poor prognosis in cervical cancer.

Aim:

To determine the expression of cyclin-A and cyclin-E, types of HR-HPV and physical state of DNA in cytologies with the diagnosis of low-grade squamous intraepithelial lesion (LSIL).

Materials and Methods:

115 cytological specimens in liquid base (liquid-PREP^™) were analyzed. 25 specimens were with no signs of SIL (NSIL) and without HPV; 30 with NSIL with low-risk HPV (LR-HPV); 30 with NSIL with HR-HPV; and 30 with both LSIL and HR-HPV. The expression of cyclins was evaluated by immunocytochemistry; and the detection of viral DNA was done by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLPs) for genotyping or sequencing of HPV. The physical state of HPV was evaluated by in situ hybridization with amplification with tyramide.

Results:

In the cytologies NSIL with LR-HPV, the expression of cyclin-A and cyclin-E was found respectively in 23.3% and 33.3% of the specimens. Among the specimens of NSIL with HR-HPV, 33.3% expressed cyclin-A and 40% cyclin-E, while 100% of the LSILs expressed the 2 cyclins. On the other hand, 100% of the samples NSIL with LR-HPV presented an episomal pattern. Of the specimens of NSIL with HR-HPV, 56.6% exhibited an episomal pattern, 23.3% integrated and 20%, mixed. Among the LSILs, 90% were mixed and 10% integrated.

Conclusions:

The cyclins A and E are present in the LSILs that occur predominantly in mixed state in the presence of HR-HPV.

Prognostic Significance of Cell Cycle- and Invasion-Related Molecular Markers and Genomic Instability in Primary Carcinoma of the Vagina

Objective

This study aimed to analyze the prognostic value of DNA content and biological markers for cell cycle regulation and invasion in primary carcinoma of the vagina (PCV).

Material and Methods

Seventy-two consecutive patients with PCV, categorized as short-term (≤2 years) and long-term (≥8 years) survivors, were evaluated for DNA content by image cytometry, and for expression of p53, p21, cyclin A, Ki67, E-cadherin, and laminin-5γ2 chain by immunohistochemistry. The relationship between these biological markers and histopathological and clinical parameters was assessed.

Results

All PCV showed aneuploid DNA content. Most of the PCV patients showed no overexpression of p53 and high expression of p21, cyclin A, and Ki67. Loss or underexpression of E-cadherin was found in 94% (68/72) of PCV patients, and all patients showed immunopositivity for the laminin-5γ2 chain. Tumors with a vaginal longitudinal location in the lower third or in the entire vagina more often had overexpression of p53, high expression of Ki67 (P = 0.044), and underexpression of E-cadherin (P = 0.038), than tumors confined only to the upper third. Overexpression of p53 was significantly associated with short-term survival in the univariate analysis, but not in the multivariate analysis adjusted for age at diagnosis and tumor size.

Conclusions

The expression level of some markers was related to tumor location, which might be indicative of different genesis. Overexpression of p53 was associated with short-term survival, but the only independent predictors of survival were age at diagnosis and tumor size.

Tissue biomarkers as prognostic variables of cervical cancer

The most important prognostic variables of cervical carcinoma are FIGO stage, lymph node status and clinical-pathological features of primary tumor. Recently, there has been increasing interest in the identification of biomarkers able to predict both response to treatment and survival. The aim of this review is to critically evaluate current published evidence on the ability of various tissue biomarkers to predict the clinical outcome of patients with cervical carcinoma. In particular, the paper takes into account DNA content, cell-cycle and apoptosis-regulatory proteins, epidermal growth factor receptor [EGFR], vascular endothelial growth factor [VEGF], cyclooxygenase [COX]-2, signal transducer and activator of transcription [Stat]3, human papilloma virus [HPV] status, tumor hypoxia, tumor infiltrating lymphocytes [TIL], microarray technology and microRNA (miRNA). The presence of HPV-18 genotype and an elevated VEGF expression appear to be poor prognostic factors in women with early disease treated with primary surgery, whereas the expression of EGFR, VEGF, COX-2 and tumor hypoxia may have a major impact on the survival of patients treated with definitive radiotherapy or chemoradiation. The data supporting the reliability of ΔNp73 and TAp73α as novel biomarkers of response to radiotherapy are interesting but still limited. DNA microarray technology could offer new laboratory tools for a rationale planning of treatment strategy, and miRNAs might represent new candidate targets to be investigated for both prognostic and therapeutic purposes. Moreover, the assessment of different types of TIL and their ligands in tumor biopsies could enable the identification of a subset of high-risk patients, paving the way to novel immune therapies aimed at blocking T-reg cell activity.

Altered expression of p27(Kip1) -interacting cell-cycle regulators in the adult testicular germ cell tumors: potential role in tumor development and histological progression

We examined the potential role of cell-cycle dysregulation in the development and histological progression of adult testicular germ cell tumors (TGCTs). Expressions of p27(Kip1) -interacting cell-cycle regulators (down-regulation of p27(Kip1) and overexpression of Skp2, Cks1, cyclin A, and cyclin E) and Ki-67 labeling index (LI) were immunohistochemically examined in histological components of 50 intratubular germ cell neoplasms, unclassified (IGCNUs); 74 seminomas; and 25 embryonal carcinomas, identified from 88 patients. Altered expression of p27(Kip1) , Skp2, Cks1, cyclin A, and cyclin E was observed in 20%, 12%, 16%, 10%, and 24% of IGCNUs; 26%, 36%, 27%, 89%, and 23% of seminomas; and 48%, 68%, 56%, 100%, and 60% of embryonal carcinomas, respectively. A significant difference in the frequency of Skp2 and cyclin A overexpression was observed between IGCNUs and seminomas. Significantly more frequent alterations of Skp2, Cks1, and cyclin E and p27(Kip1) were detected in embryonal carcinomas than in seminomas. Alterations of all cell-cycle regulators were significantly more frequent in embryonal carcinomas than in IGCNUs. The mean Ki-67 LI significantly increased from IGCNU (21.2%) through seminoma (34.7%) to embryonal carcinoma (54.2%). These results suggest that alterations of the p27(Kip1) -interacting cell-cycle regulators are common in TGCTs and may be involved in their histological progression.

Correlation of p53 and Ki-67 (MIB-1) expressions with clinicopathological features and prognosis of early stage cervical squamous cell carcinomas

AIM

To evaluate the prognostic significance of the expression of p53 and Ki-67, and their correlation with various clinicopathological factors in patients with squamous cell carcinoma of the uterine cervix treated by radical hysterectomy.

METHODS

Two hundred and thirty five patients diagnosed between 1987 and 2004 were investigated for p53 and Ki-67 expression by immunohistochemistry. The relationship of these proteins and other potential prognostic factors with recurrence-free survival (RFS) was evaluated.

RESULTS

The mean age of the patients was 43.9 years (range, 27-68). There were 28 cases with stage IA2 (11.9%) and 207 cases with stage IB1 (88.1%). The overall 5-year RFS was 91.1% (95% confidence interval [CI] 86.0, 94.4). p53 and Ki-67 expressions were seen in 33.6% and 81.3% of cases, respectively. p53 expression was significantly associated only with parametrial or marginal involvement (P = 0.005), while Ki-67 expression significantly correlated only with larger tumor (P = 0.011) and parametrial or marginal involvement (P = 0.024). There was significant correlation between the expression of p53 and Ki-67 (P = 0.021). In multivariate analysis, Ki-67 expression (hazard ratio for >or=3rd vs 1st tertile [>or=30% vs <20% expression] = 16.0, 95%CI 2.1-124.5; P = 0.0015) appeared to be an independent prognostic factor for RFS, while no prognostic significance of p53 expression was found.

CONCLUSION

Ki-67 expression is an independent prognostic parameter for RFS in patients with early stage squamous cell carcinoma of the uterine cervix. Ki-67 expression at or above the cut-off point of 30.0% had significantly poorer RFS.

Tissue tumor marker expression in smokers, including serum cotinine concentrations, in women with cervical intraepithelial neoplasia or normal squamous cervical epithelium

OBJECTIVE

The purpose of this study was to investigate correlations between smoking and serum cotinine, respectively, and tumor marker expression in cervical intraepithelial neoplasia (CIN) and normal epithelium.

STUDY DESIGN

Women (n = 228) with cervical biopsy specimens that ranged histologically from normal to carcinoma in situ (CIN III) were included. Expression of 11 tumor markers with possible relevance in cervical neoplasms was studied. Smoking habits were recorded, and serum was assessed for cotinine concentrations.

RESULTS

No differences were found in tumor marker expression in normal epithelium between smokers and nonsmokers. The tumor suppressors p53 and fragile histidine triad and the immunologic marker interleukin-10 were underexpressed, and the tumor markers cyclooxygenase-2 and Ki-67 were overexpressed in smoking, compared with nonsmoking, women with CIN and particularly in all fertile women.

CONCLUSION

The molecular pattern indicates that smoking exerts unfavorable effects in cervical neoplasia. This provides biologic evidence of smoking being a true cofactor in cervical neoplasia.

Differences in protein expression and gene amplification of cyclins between colon and rectal adenocarcinomas

Adenocarcinomas of rectum and colon may be different with regard to the cellular biological basis for cancer development. A material of 246 rectal cancers removed surgically at Akershus University Hospital in the years 1992–2000 was investigated and was compared to a material of 219 colon cancers operated on at Akershus University Hospital during the years 1988, 1990 and 1997–2000. There were highly significant differences between the rectal and the colon cancers in the protein expression of cyclin D1, cyclin D3, cyclin E, nuclear β-catenin, and c-Myc and in gene amplification of cyclin A2, cyclin B1, cyclin D1, and cyclin E. Gene amplification and protein expression in the rectal cancers correlated significantly for the cyclins B1, D3, and E. A statistically significant relation was observed between overexpression of cyclin A2 and local relapse of rectal carcinomas, as higher expression of cyclin A2 was associated with lower local recurrence rate.

Cyclin A expression is associated with apoptosis and mitosis in murine 3-methylcholanthrene-induced fibrosarcomas

The chemical carcinogen MCA induces fibrosarcoma and tissue damage at the injection site. Despite the importance of ROS in the development of cancer, little is known about the pattern of expression of ROS in MCA-induced fibrosarcomas. To gain some insight into the biological significance of iNOS and Cu/Zn-SOD, comparative immunohistochemical analyses were performed to characterize their expression in MCA-induced fibrosarcomas. Cyclin A is overexpressed in various tumors, but its expression in MCA-induced fibrosarcoma in mice and its correlation to mitosis and apoptosis are unclear. The presence of apoptotic cell death was evaluated using the TUNEL method and findings were compared with cyclin A expression and mitotic count of fibrosarcomas. Subcutaneous application of MCA caused fibrosarcoma development in 14 of 20 mice (70%) in 26 weeks. Limited cytoplasmic Cu/Zn-SOD and iNOS immunostainings were detected in 13 of 14 and 9 of 14 tumors with median immunoreactive scores of 2 and 1, respectively. Prominent nuclear cyclin A immunostaining and TUNEL-positive reactions were seen in all the fibrosarcoma cases. Cyclin A immunoreaction significantly correlated with the TUNEL index (P<0.01) and MC (P<0.001). The present findings show a low level of iNOS expression in neoplastic cells indicating limited synthesizing capacity of tumor cells. Limited Cu/Zn-SOD reaction could be associated with an imbalance in between pro-oxidant/antioxidant levels. Furthermore, it was shown that cyclin A is overexpressed in MCA-induced fibrosarcomas and possibly plays a significant role in the pathogenesis of fibrosarcomas. Cyclin A could be useful for detecting the S phase of the cell cycle and could also indicate that cyclin A may induce S phase arrest associated with apoptosis in the MCA-induced fibrosarcomas.