Apoptosis, intrinsic radiosensitivity and prediction of radiotherapy response in cervical carcinoma

Studying the regression profiles of cervical tumours during radiotherapy treatment using a patient-specific multiscale model

Apart from offering insight into the biomechanisms involved in cancer, many recent mathematical modeling efforts aspire to the ultimate goal of clinical translation, wherein models are designed to be used in the future as clinical decision support systems in the patient-individualized context. Most significant challenges are the integration of multiscale biodata and the patient-specific model parameterization. A central aim of this study was the design of a clinically-relevant parameterization methodology for a patient-specific computational model of cervical cancer response to radiotherapy treatment with concomitant cisplatin, built around a tumour features-based search of the parameter space. Additionally, a methodological framework for the predictive use of the model was designed, including a scoring method to quantitatively reflect the similarity and bilateral predictive ability of any two tumours in terms of their regression profile. The methodology was applied to the datasets of eight patients. Tumour scenarios in accordance with the available longitudinal data have been determined. Predictive investigations identified three patient cases, anyone of which can be used to predict the volumetric evolution throughout therapy of the tumours of the other two with very good results. Our observations show that the presented approach is promising in quantifiably differentiating tumours with distinct regression profiles.

Chemoradiation therapy induces in vivo changes in gene promoter methylation & gene transcript expression in patients with invasive cervical cancer

Background & objectives:

Invasive cervical cancer patients are primarily treated with chemoradiation therapy. The overall and disease-free survival in these patients is variable and depends on the tumoral response apart from the tumour stage. This study was undertaken to assess whether in vivo changes in gene promoter methylation and transcript expression in invasive cervical cancer were induced by chemoradiation. Hence, paired pre- and post-treatment biopsy samples were evaluated for in vivo changes in promoter methylation and transcript expression of 10 genes (ESR1, BRCA1, RASSF1A, MYOD1, MLH1, hTERT, MGMT, DAPK1, BAX and BCL2L1) in response to chemoradiation therapy.

Methods:

In patients with locally advanced invasive cervical cancer, paired pre- and post-treatment biopsies after 10 Gy chemoradiation were obtained. DNA/RNA was extracted and gene promoter methylation status was evaluated by custom-synthesized methylation PCR arrays, and the corresponding gene transcript expression was determined by absolute quantification method using quantitative reverse transcription PCR.

Results:

Changes in the gene promoter methylation as well as gene expression following chemoradiation therapy were observed. BAX promoter methylation showed a significant increase (P< 0.01) following treatment. There was a significant increase in the gene transcript expression of BRCA1 (P< 0.01), DAPK1 and ESR1 (P< 0.05), whereas MYOD1 and MLH1 gene transcript expression was significantly decreased (P< 0.05) following treatment.

Interpretation & conclusions:

The findings of our study show that chemoradiation therapy can induce epigenetic alterations as well as affect gene expression in tissues of invasive cervical cancer which may have implications in determining radiation response.

Exploitation of Apoptotic Regulation in Cancer

Within an organism, environmental stresses can trigger cell death, particularly apoptotic cell death. Apoptotic cells, themselves, are potent regulators of their cellular environment, involved primarily in effecting homeostatic control. Tumors, especially, exist in a dynamic balance of cell proliferation and cell death. This special feature of the tumorous microenvironment—namely, the prominence and persistence of cell death—necessarily entails a magnification of the extrinsic, postmortem effects of dead cells. In both normal and malignant tissues, apoptotic regulation is exerted through immune as well as non-immune mechanisms. Apoptotic cells suppress the repertoire of immune reactivities, both by attenuating innate (especially inflammatory) responses and by abrogating adaptive responses. In addition, apoptotic cells modulate multiple vital cell activities, including survival, proliferation (cell number), and growth (cell size). While the microenvironment of the tumor may contribute to apoptosis, the postmortem effects of apoptotic cells feature prominently in the reciprocal acclimatization between the tumor and its environment. In much the same way that pathogens evade the host’s defenses through exploitation of key aspects of innate and adaptive immunity, cancer cells subvert several normal homeostatic processes, in particular wound healing and organ regeneration, to transform and overtake their environment. In understanding this subversion, it is crucial to view a tumor not simply as a clone of malignant cells, but rather as a complex and highly organized structure in which there exists a multidirectional flow of information between the cancer cells themselves and the multiple other cell types and extracellular matrix components of which the tumor is comprised. Apoptotic cells, therefore, have the unfortunate consequence of facilitating tumorigenesis and tumor survival.

Targeting Hypoxia to Improve Non-Small Cell Lung Cancer Outcome

Oxygen deprivation (hypoxia) in non-small cell lung cancer (NSCLC) is an important factor in treatment resistance and poor survival. Hypoxia is an attractive therapeutic target, particularly in the context of radiotherapy, which is delivered to more than half of NSCLC patients. However, NSCLC hypoxia-targeted therapy trials have not yet translated into patient benefit. Recently, early termination of promising evofosfamide and tarloxotinib bromide studies due to futility highlighted the need for a paradigm shift in our approach to avoid disappointments in future trials. Radiotherapy dose painting strategies based on hypoxia imaging require careful refinement prior to clinical investigation. This review will summarize the role of hypoxia, highlight the potential of hypoxia as a therapeutic target, and outline past and ongoing hypoxia-targeted therapy trials in NSCLC. Evidence supporting radiotherapy dose painting based on hypoxia imaging will be critically appraised. Carefully selected hypoxia biomarkers suitable for integration within future NSCLC hypoxia-targeted therapy trials will be examined. Research gaps will be identified to guide future investigation. Although this review will focus on NSCLC hypoxia, more general discussions (eg, obstacles of hypoxia biomarker research and developing a framework for future hypoxia trials) are applicable to other tumor sites.

Biomarkers in Cervical Cancer

Cervical cancer, a potentially preventable disease, remains the second most common malignancy in women worldwide. Human papillomavirus (HPV) is the single most important etiological agent in cervical cancer, contributing to neoplastic progression through the action of viral oncoproteins, mainly E6 and E7. Cervical screening programs using Pap smear testing have dramatically improved cervical cancer incidence and reduced deaths, but cervical cancer still remains a global health burden. The biomarker discovery for accurate detection and diagnosis of cervical carcinoma and its malignant precursors (collectively referred to as high-grade cervical disease) represents one of the current challenges in clinical medicine and cytopathology.

Comparison between model-predicted tumor oxygenation dynamics and vascular-/flow-related Doppler indices

PURPOSE

Mathematical modeling is a powerful and flexible method to investigate complex phenomena. It discloses the possibility of reproducing expensive as well as invasive experiments in a safe environment with limited costs. This makes it suitable to mimic tumor evolution and response to radiotherapy although the reliability of the results remains an issue. Complexity reduction is therefore a critical aspect in order to be able to compare model outcomes to clinical data. Among the factors affecting treatment efficacy, tumor oxygenation is known to play a key role in radiotherapy response. In this work, we aim at relating the oxygenation dynamics, predicted by a macroscale model trained on tumor volumetric data of uterine cervical cancer patients, to vascularization and blood flux indices assessed on Ultrasound Doppler images.

METHODS

We propose a macroscale model of tumor evolution based on three dynamics, namely active portion, necrotic portion, and oxygenation. The model parameters were assessed on the volume size of seven cervical cancer patients administered with 28 fractions of intensity modulated radiation therapy (IMRT) (1.8 Gy/fraction). For each patient, five Doppler ultrasound tests were acquired before, during, and after the treatment. The lesion was manually contoured by an expert physician using 4D View^® (General Electric Company - Fairfield, Connecticut, United States), which automatically provided the overall tumor volume size along with three vascularization and/or blood flow indices. Volume data only were fed to the model for training purpose, while the predicted oxygenation was compared a posteriori to the measured Doppler indices.

RESULTS

The model was able to fit the tumor volume evolution within 8% error (range: 3-8%). A strong correlation between the intrapatient longitudinal indices from Doppler measurements and oxygen predicted by the model (about 90% or above) was found in three cases. Two patients showed an average correlation value (50-70%) and the remaining two presented poor correlations. The latter patients were the ones featuring the smallest tumor reduction throughout the treatment, typical of hypoxic conditions. Moreover, the average oxygenation value predicted by the model was close to the average vascularization-flow index (average difference: 7%).

CONCLUSIONS

The results suggest that the modeled relation between tumor evolution and oxygen dynamics was reasonable enough to provide realistic oxygenation curves in five cases (correlation greater than 50%) out of seven. In case of nonresponsive tumors, the model failed in predicting the oxygenation trend while succeeded in reproducing the average oxygenation value according to the mean vascularization-flow index. Despite the need for deeper investigations, the outcomes of the present work support the hypothesis that a simple macroscale model of tumor response to radiotherapy is able to predict the tumor oxygenation. The possibility of an objective and quantitative validation on imaging data discloses the possibility to translate them as decision support tools in clinical practice and to move a step forward in the treatment personalization.

Glut-1 expression in small cervical biopsies is prognostic in cervical cancers treated with chemoradiation

BACKGROUND/PURPOSE

Chemoradiation (CRT) is standard therapy for locally advanced cervical cancer (LACC). However, there is a lack of biomarkers to identify patients at high relapse-risk. We examine metabolic (glucose transporter-1 [Glut-1]), hypoxic (hypoxia inducible factor [HIF-1α]; carbonic anhydrase [CA-9]) and proliferative (Ki-67) markers for prognostic utility in LACC.

MATERIALS/METHODS

60 LACC patients treated with CRT had pre-treatment biopsies. Immunohistochemistry was performed for Glut-1, HIF-1a and CA-9, to generate a histoscore from intensity and percentage staining; and Ki-67 scored by percentage of positive cells. For each biomarker, treatment response and survival was compared between low and high-staining groups by logrank testing and multivariate analyses.

RESULTS

High Glut-1 expression was associated with inferior progression-free survival (PFS), (hazard ratio [HR] 2.8, p = 0.049) and overall survival (OS), (HR 5.0, p = 0.011) on multifactor analysis adjusting for stage, node positivity, tumour volume and uterine corpus invasion. High Glut-1 correlated with increased risk of distant failure (HR 14.6, p = 0.001) but not local failure. Low Glut-1 was associated with higher complete metabolic response rate on post-therapy positron emission tomography scan (odds ratio 3.4, p = 0.048). Ki-67 was significantly associated with PFS only (HR 1.19 per 10 units increase, p = 0.033). Biomarkers for hypoxia were not associated with outcome.

CONCLUSIONS

High Glut-1 in LACC is associated with poor outcome post CRT. If prospectively validated, Glut-1 may help select patients for more intensive treatment regimens.

The changing paradigm of tumour response to irradiation

Tumours contain multiple different cell populations, including cells derived from the bone marrow as well as cancer-associated fibroblasts and various stromal populations including the vasculature. The microenvironment of the tumour cells plays a significant role in the response of the tumour to radiation treatment. Low levels of oxygen (hypoxia) caused by the poorly organized vasculature in tumours have long been known to affect radiation response; however, other aspects of the microenvironment may also play important roles. This article reviews some of the old literature concerning tumour response to irradiation and relates this to current concepts about the role of the tumour microenvironment in tumour response to radiation treatment. Included in the discussion are the role of cancer stem cells, radiation damage to the vasculature and the potential for radiation to enhance immune activity against tumour cells. Radiation treatment can cause a significant influx of bone marrow-derived cell populations into both normal tissues and tumours. Potential roles of such cells may include enhancing vascular recovery as well as modulating immune reactivity.

Apoptotic and Mitotic Index in Squamous Cell Carcinomas and Premalignant Lesions of the Uterine Cervix

The aim of this study was to determine the frequency of apoptotic and mitotic cells in different grades of premalignant lesions and in different stages of squamous cell carcinoma (SCC) of the uterine cervix. The apoptotic and mitotic indices (A! and MI) of 55 H&E-stained sections of cervical intraepithelial neoplasia (CIN) and 30 SCCs were evaluated in light microscopy by a morphometric method. Twenty, 16, and 19 of 55 CIN cases were classified in CIN I, CIN II, and CIN III group, respectively. No apoptosis was observed in the normal epithelium next to the dysplastic mucosa. There was no statistically significant difference between CIN I and CIN II as well as CIN II and CIN III groups in terms of apoptotic and mitotic cell counts. Mitotic cell counts were found significantly higher in CIN III group when compared with CIN I and CIN II groups together. There was no statistically significant difference in the apoptotic and mitotic cell counts between nonkeratinizing and keratinizing types of SCC. In the SCC group, apoptotic cell counts did not show significant difference between tumor stages. But mitotic counts were significantly higher in advanced stage tumors. The SCC group showed significantly higher mitotic and apoptotic cell counts when compared with preneoplastic lesions. This study suggests that apoptotic function is not altered during progressive stages of dysplastic change in cervical epithelium, while proliferation is triggered only in late stages of dysplasia. Both apoptosis and mitosis are markedly increased in progression to malignancy in cervix epithelium. Mitotic cell counts may be helpful in predicting the extent of the disease in SCC. Resistance of cell death by apoptosis after invasion may accelerate the net growth of the tumor resulting in advanced disease.

Ex Vivo Apoptosis in CD8+ Lymphocytes Predicts Rectal Cancer Patient Outcome

Background. Apoptotic rates in peripheral blood lymphocytes can predict radiation induced normal tissue toxicity. We studied whether apoptosis in lymphocytes has a prognostic value for therapy outcome. Methods. Lymphocytes of 87 rectal cancer patients were ex vivo irradiated with 2 Gy, 8 Gy, or a combination of 2 Gy ionizing radiation and Oxaliplatin. Cells were stained with Annexin V and 7-Aminoactinomycin D and apoptotic and necrotic rates were analyzed by multicolor flow cytometry. Results. After treatment, apoptotic and necrotic rates in CD8+ cells are consistently higher than in CD4+ cells, with lower corresponding necrotic rates. Apoptotic and necrotic rates of CD4+ cells and CD8+ cells correlated well within the 2 Gy, 8 Gy, and 2 Gy and Oxaliplatin arrangements (p ≤ 0.009). High apoptotic CD8+ rates after 2 Gy, 8 Gy, and 2 Gy + Oxaliplatin treatment were prognostically favorable for metastasis-free survival (p = 0.009, p = 0.038, and p = 0.009) and disease-free survival (p = 0.013, p = 0.098, and p = 0.013). Conclusions. Ex vivo CD8+ apoptotic rates are able to predict the patient outcome in regard to metastasis-free or disease-free survival. Patients with higher CD8+ apoptotic rates in the peripheral blood have a more favorable prognosis. In addition to the prediction of late-toxicity by utilization of CD4+ apoptotic rates, the therapy outcome can be predicted by CD8+ apoptotic rates.

Raman spectroscopy identifies radiation response in human non-small cell lung cancer xenografts

External beam radiation therapy is a standard form of treatment for numerous cancers. Despite this, there are no approved methods to account for patient specific radiation sensitivity. In this report, Raman spectroscopy (RS) was used to identify radiation-induced biochemical changes in human non-small cell lung cancer xenografts. Chemometric analysis revealed unique radiation-related Raman signatures that were specific to nucleic acid, lipid, protein and carbohydrate spectral features. Among these changes was a dramatic shift in the accumulation of glycogen spectral bands for doses of 5 or 15 Gy when compared to unirradiated tumours. When spatial mapping was applied in this analysis there was considerable variability as we found substantial intra- and inter-tumour heterogeneity in the distribution of glycogen and other RS spectral features. Collectively, these data provide unique insight into the biochemical response of tumours, irradiated in vivo, and demonstrate the utility of RS for detecting distinct radiobiological responses in human tumour xenografts.

Inhibition of tribbles protein-1 attenuates radioresistance in human glioma cells

Radiotherapy is one of the remedies in the treatment of glioma. The radioresistance is a major drawback, of which the mechanism is unclear. Tribble protein and histone deacetylase are involved in the cancer pathogenesis. This study aims to test a hypothesis that the histone deacetylase inhibitors attenuate the radioresistance in human glioma cells. In this study, human glioma cells were cultured. The cells were treated with irradiation with or without a histone deacetylase inhibitor, butyrate. Apoptosis of the glioma cells was assessed by flow cytometry. The results showed that human glioma cells expressed a low level of Trib1, which was significantly up regulated by exposure to small doses (2 Gy/day for 4 days) of irradiation. Trib1-deficient glioma cells showed an enhanced response to irradiation-induced apoptosis. Exposure to small doses of irradiation, Trib1 formed a complex with pHDAC1 (phosphor histone deacetylase-1) to inhibit p53 expression in glioma cells. The presence of HDAC1 inhibitor, butyrate or parthenolide, significantly enforced irradiation-induced glioma cell apoptosis. In conclusion, the Trib1 plays a critical role in the development of radioresistance of glioma cells. The data suggest that inhibition of Trib1 or HDAC1 has the potential to prevent or attenuate the radioresistance.

Factors affecting platinum sensitivity in cervical cancer

The present study aimed to investigate the association between nedaplatin (NDP) sensitivity and the expression of biological factors in cervical cancer. A total of 45 cervical cancer specimens, including 18 pretreatment biopsies and 27 surgical specimens, were used in histoculture drug response assays to determine the chemosensitivity of cervical cancer specimens to NDP. Each specimen was assessed for immunohistochemical expression of Ki-67, p53, B-cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), cleaved caspase-3, cyclooxygenase-2 (COX-2), and excision repair cross-complementation group 1 (ERCC1). The results revealed that low or negative expression of p53, Bcl-2 and COX-2, and high or positive expression of cleaved caspase-3 were significantly correlated with high sensitivity to NDP. However, there were no significant differences in Ki-67, Bax or ERCC1 expression between the low and high sensitivity groups. These findings indicate that sensitivity to platinum may be easily predicted by immunostaining for the detection of these specific factors in pretreatment biopsies or surgical specimens. The expression profiles of these targets may therefore provide additional information for planning individualized chemotherapy in the treatment of cervical cancer.

Kinetic Models for Predicting Cervical Cancer Response to Radiation Therapy on Individual Basis Using Tumor Regression Measured In Vivo With Volumetric Imaging

This article describes a macroscopic mathematical modeling approach to capture the interplay between solid tumor evolution and cell damage during radiotherapy. Volume regression profiles of 15 patients with uterine cervical cancer were reconstructed from serial cone-beam computed tomography data sets, acquired for image-guided radiotherapy, and used for model parameter learning by means of a genetic-based optimization. Patients, diagnosed with either squamous cell carcinoma or adenocarcinoma, underwent different treatment modalities (image-guided radiotherapy and image-guided chemo-radiotherapy). The mean volume at the beginning of radiotherapy and the end of radiotherapy was on average 23.7 cm(3) (range: 12.7-44.4 cm(3)) and 8.6 cm(3) (range: 3.6-17.1 cm(3)), respectively. Two different tumor dynamics were taken into account in the model: the viable (active) and the necrotic cancer cells. However, according to the results of a preliminary volume regression analysis, we assumed a short dead cell resolving time and the model was simplified to the active tumor volume. Model learning was performed both on the complete patient cohort (cohort-based model learning) and on each single patient (patient-specific model learning). The fitting results (mean error: ∼ 16% and ∼ 6% for the cohort-based model and patient-specific model, respectively) highlighted the model ability to quantitatively reproduce tumor regression. Volume prediction errors of about 18% on average were obtained using cohort-based model computed on all but 1 patient at a time (leave-one-out technique). Finally, a sensitivity analysis was performed and the data uncertainty effects evaluated by simulating an average volume perturbation of about 1.5 cm(3) obtaining an error increase within 0.2%. In conclusion, we showed that simple time-continuous models can represent tumor regression curves both on a patient cohort and patient-specific basis; this discloses the opportunity in the future to exploit such models to predict how changes in the treatment schedule (number of fractions, doses, intervals among fractions) might affect the tumor regression on an individual basis.

Modeling the Interplay Between Tumor Volume Regression and Oxygenation in Uterine Cervical Cancer During Radiotherapy Treatment

This paper describes a patient-specific mathematical model to predict the evolution of uterine cervical tumors at a macroscopic scale, during fractionated external radiotherapy. The model provides estimates of tumor regrowth and dead-cell reabsorption, incorporating the interplay between tumor regression rate and radiosensitivity, as a function of the tumor oxygenation level. Model parameters were estimated by minimizing the difference between predicted and measured tumor volumes, these latter being obtained from a set of 154 serial cone-beam computed tomography scans acquired on 16 patients along the course of the therapy. The model stratified patients according to two different estimated dynamics of dead-cell removal and to the predicted initial value of the tumor oxygenation. The comparison with a simpler model demonstrated an improvement in fitting properties of this approach (fitting error average value <5%, p < 0.01), especially in case of tumor late responses, which can hardly be handled by models entailing a constant radiosensitivity, failing to model changes from initial severe hypoxia to aerobic conditions during the treatment course. The model predictive capabilities suggest the need of clustering patients accounting for cancer cell line, tumor staging, as well as microenvironment conditions (e.g., oxygenation level).

A Raman spectroscopic study of cell response to clinical doses of ionizing radiation

The drive toward personalized radiation therapy (RT) has created significant interest in determining patient-specific tumor and normal tissue responses to radiation. Raman spectroscopy (RS) is a non-invasive and label-free technique that can detect radiation response through assessment of radiation-induced biochemical changes in tumor cells. In the current study, single-cell RS identified specific radiation-induced responses in four human epithelial tumor cell lines: lung (H460), breast (MCF-7, MDA-MB-231), and prostate (LNCaP), following exposure to clinical doses of radiation (2-10 Gy). At low radiation doses (2 Gy), H460 and MCF-7 cell lines showed an increase in glycogen-related spectral features, and the LNCaP cell line showed a membrane phospholipid-related radiation response. In these cell lines, only spectral information from populations receiving 10 Gy or less was required to identify radiation-related features using principal component analysis (PCA). In contrast, the MDA-MB-231 cell line showed a significant increase in protein relative to nucleic acid and lipid spectral features at doses of 6 Gy or higher, and high-dose information (30, 50 Gy) was required for PCA to identify this biological response. The biochemical nature of the radiation-related changes occurring in cells exposed to clinical doses was found to segregate by status of p53 and radiation sensitivity. Furthermore, the utility of RS to identify a biological response in human tumor cells exposed to therapeutic doses of radiation was found to be governed by the extent of the biochemical changes induced by a radiation response and is therefore cell line specific. The results of this study demonstrate the utility and effectiveness of single-cell RS to identify and measure biological responses in tumor cells exposed to standard radiotherapy doses.

Apoptotic HPV positive cancer cells exhibit transforming properties

Previous studies have shown that DNA can be transferred from dying engineered cells to neighboring cells through the phagocytosis of apoptotic bodies, which leads to cellular transformation. Here, we provide evidence of an uptake of apoptotic-derived cervical cancer cells by human mesenchymal cells. Interestingly, HeLa (HPV 18+) or Ca Ski (HPV16+) cells, harboring integrated high-risk HPV DNA but not C-33 A cells (HPV-), were able to transform the recipient cells. Human primary fibroblasts engulfed the apoptotic bodies effectively within 30 minutes after co-cultivation. This mechanism is active and involves the actin cytoskeleton. In situ hybridization of transformed fibroblasts revealed the presence of HPV DNA in the nucleus of a subset of phagocytosing cells. These cells expressed the HPV16/18 E6 gene, which contributes to the disruption of the p53/p21 pathway, and the cells exhibited a tumorigenic phenotype, including an increased proliferation rate, polyploidy and anchorage independence growth. Such horizontal transfer of viral oncogenes to surrounding cells that lack receptors for HPV could facilitate the persistence of the virus, the main risk factor for cervical cancer development. This process might contribute to HPV-associated disease progression in vivo.

Biochemical signatures of in vitro radiation response in human lung, breast and prostate tumour cells observed with Raman spectroscopy

This work applies noninvasive single-cell Raman spectroscopy (RS) and principal component analysis (PCA) to analyze and correlate radiation-induced biochemical changes in a panel of human tumour cell lines that vary by tissue of origin, p53 status and intrinsic radiosensitivity. Six human tumour cell lines, derived from prostate (DU145, PC3 and LNCaP), breast (MDA-MB-231 and MCF7) and lung (H460), were irradiated in vitro with single fractions (15, 30 or 50 Gy) of 6 MV photons. Remaining live cells were harvested for RS analysis at 0, 24, 48 and 72 h post-irradiation, along with unirradiated controls. Single-cell Raman spectra were acquired from 20 cells per sample utilizing a 785 nm excitation laser. All spectra (200 per cell line) were individually post-processed using established methods and the total data set for each cell line was analyzed with PCA using standard algorithms. One radiation-induced PCA component was detected for each cell line by identification of statistically significant changes in the PCA score distributions for irradiated samples, as compared to unirradiated samples, in the first 24-72 h post-irradiation. These RS response signatures arise from radiation-induced changes in cellular concentrations of aromatic amino acids, conformational protein structures and certain nucleic acid and lipid functional groups. Correlation analysis between the radiation-induced PCA components separates the cell lines into three distinct RS response categories: R1 (H460 and MCF7), R2 (MDA-MB-231 and PC3) and R3 (DU145 and LNCaP). These RS categories partially segregate according to radiosensitivity, as the R1 and R2 cell lines are radioresistant (SF(2) > 0.6) and the R3 cell lines are radiosensitive (SF(2) < 0.5). The R1 and R2 cell lines further segregate according to p53 gene status, corroborated by cell cycle analysis post-irradiation. Potential radiation-induced biochemical response mechanisms underlying our RS observations are proposed, such as (1) the regulated synthesis and degradation of structured proteins and (2) the expression of anti-apoptosis factors or other survival signals. This study demonstrates the utility of RS for noninvasive radiobiological analysis of tumour cell radiation response, and indicates the potential for future RS studies designed to investigate, monitor or predict radiation response.

Zoledronic acid decreases mRNA six-transmembrane epithelial antigen of prostate protein expression in prostate cancer cells

BACKGROUND

Zoledronic acid (Zol) is used successfully to inhibit bone resorption in tumor bone disease of various human cancer. Zol inhibits the mevalonate pathway and other potential targets include the inhibition of tyrosine phosphatase activity, disruption of metalloproteinase, secretion and down-regulation of the catalytic subunit of telomerase (hTERT). The six-transmembrane epithelial antigen of prostate protein (STEAP) is a new marker highly expressed at all phases of prostate cancer.

AIM

Here, we analyzed for the first time the effect of Zol on STEAP gene expression in prostate cancer cells.

MATERIAL AND METHODS

We evaluated the effects of Zol in STEAP gene expression by RT real time PCR in androgen-sensitive (LNCaP) and androgen-non-sensitive (PC3 and DU145) cell lines. To confirm the pro-apoptotic effect of Zol, we also analyzed the caspase-3 gene expression, that resulted up-regulated in cancer cell apoptosis.

RESULTS

Zol strongly decreased cell viability and lowered STEAP gene expression in a dose-dependent manner. In addition, this effect was accompanied by an increase of apoptotic index and an up-regulation of caspase-3 gene expression.

CONCLUSION

Zol may affect cancer cells also by targeting the gene expression of STEAP.

Apoptosis in human reproductive tissues: emerging concepts

In summary, apoptosis is an important concept in understanding many facets of human reproduction. Recent advances in the understanding of molecular mechanisms of apoptosis will allow us to understand this physiologically important process. How can the modulation of this process be applied to human reproduction? Studies to further understand the abnormalities of apoptosis, either too much or too little, may lead to a better understanding of the clinical problems in human reproduction.

We summarize future directions towards further understanding the roles of apoptotic processes in human reproduction in Table 3. The diseases listed in Table 3 are problems which could be approached from the apoptosis point of view. With further study using this concept as the lens, new diagnostic tools or therapies may be developed for these problems.

Using Q-RT-PCR to measure cyclin D1, TS, TP, DPD, and Her-2/neu as predictors for response, survival, and recurrence in patients with esophageal squamous cell carcinoma following radiochemotherapy

PURPOSE

The purpose of this study was to evaluate the use of thymidilate synthetase (TS), thymidilate phosphorylase (TP), dihydropyrimidin dehydrogenase (DPD), Her-2/neu, and cyclin D1 as predictors of therapy response, survival, and recurrence in patients with esophageal squamous cell carcinoma (ESCC) following radiochemotherapy.

MATERIALS AND METHODS

Twenty-six patients with histologically proven intrathoracic, locally advanced ESCC (cT3, cN0/+, cM0) underwent preoperative, combined simultaneous radiochemotherapy followed by R0-transthoracic esophagectomy. Because R0 resection is the strongest known independent prognostic factor in this tumor entity, only R0-resected patients were included in this study. Pre-therapeutically taken, formalin-fixed, and paraffin-embedded tumor biopsies were used for laser-assisted microdissection of tumor cells and RNA extraction and subjected to real-time (TaqMan) quantitative reverse transcriptase-polymerase chain reaction (Q-RT-PCR).

RESULTS

No significant correlation between clinical or histopathological parameters and the relative gene expression of TS, TP, DPD, or Her-2/neu was observed. However, patients with relative cyclin D1 levels below the median gene expression did not reach median survival compared to the 19.9 months seen in patients with relative cyclin D1 gene expression above the median (P = 0.02). Patients with low cyclin D1 levels experienced significantly less frequent recurrence of the tumor (20% versus 63%; P = 0.006), and there was a significant difference in the recurrence-free interval (P = 0.003).

CONCLUSIONS

Despite the small number of investigated patients, our data seem to show that high levels of cyclin D1 measured by real-time Q-RT-PCR before neoadjuvant radiochemotherapy correlate significantly with patient survival, tumor recurrence, and recurrence-free-interval. Cyclin D1 might be useful in identifying patients at high risk of poor prognosis and suffering from recurrence after neoadjuvant radiochemotherapy treatment and R0 resection. Further investigations with a larger cohort are warranted.

hCG beta expression by cervical squamous carcinoma--in vivo histological association with tumour invasion and apoptosis

AIMS

To investigate the correlation of beta-subunit of human chorionic gonadotrophin (hCG beta) expression by cervical carcinomas with measures of tumour apoptosis.

METHODS AND RESULTS

Eighty-nine cervical carcinoma patients' samples were subject to hCG beta immunohistochemistry and scored with respect to intensity of immunopositivity and percentage of positive cells. Apoptosis was evaluated by three independent parameters: morphological characteristics [haematoxylin and eosin (H&E)], terminal deoxynucleotidyl transferase biotin-dUTP nick end labelling (TUNEL) and poly (ADP-ribose) polymerase (PARP) immunopositivity. Of the 12 adenocarcinomas, only one (8%) was hCG beta+. However, 87% (61/70) of the squamous cell and 100% (7/7) of adenosquamous cell carcinomas were hCG beta+. hCG beta reactivity and intensity was predominantly confined to peripheral tumour cells at the stromal-epithelial interface. Correlation analysis showed that H&E and PARP apoptotic immunopositivity negatively correlated with hCG beta expression (P < 0.001 and P = 0.028 respectively), whereas TUNEL did not (P = 0.12). However, immunopositivity for apoptotic cells by TUNEL was significantly less in tumours where hCG beta expression was greater (scoring >or= 6) and vice versa. hCG beta immunopositivity was also observed in newly formed blood vessels, as well as tumour cells within lymphatic vessels. When tumour vascularization was taken into account, samples with noted vascularization positively correlated with hCG beta scoring.

CONCLUSIONS

hCG beta expression correlates with reduced tumour cell apoptosis and may be involved in tumour vascularization and dissemination.

Alteration of apoptotic signaling molecules as a function of time after radiation in human neuroblastoma cells

Ascertaining the time-dependent regulation of induced apoptosis and radioresistance is important to understand the relationship between the level of spontaneous apoptosis in cells and their radiosensitivity. Accordingly, we investigated the time-dependent expression of apoptosis related genes and radioresistance in neuroblastoma cells. Serum-starved human SK-N-MC cells were exposed to low linear energy transfer (LET) radiation (2 Gy) and incubated for 15, 30, 45 min, and 48 h. Radioresistance was investigated by examining the NF kappa B DNA-binding activity, cellular toxicity, DNA fragmentation, and expression of apoptotic signal transduction molecules. NF kappa B DNA binding activity was analyzed using electrophoretic mobility shift assay (EMSA). Cellular toxicity was measured using MTT assay. DNA fragmentation was quantified by labeling with fluorescein-conjugated deoxynucleotides. Microarray analysis was performed using cDNA microarray and relative gene expression was measured as % GAPDH and, subsequently validated using Q-PCR. Induction of NF kappa B analyzed using EMSA showed an increased DNA-binding activity at all time points investigated. Induced DNA fragmentation was observed after 15, 30, and 45 min post-radiation. Relatively, induced fragmentation was reduced after 48 h. Compared to the untreated controls cellular toxicity was induced with low LET radiation after 15, 30, and 45 min. Conversely, cytotoxicity was relatively less at 48 h after low LET radiation. Microarray analysis after low LET radiation revealed time-dependent modulation of apoptosis-related genes that are involved in radio-adaptation, spontaneous apoptosis-related early-responsive genes and late response genes. These results suggest that the time-dependent regulation of apoptotic response may determine the relationship between the level of spontaneous apoptosis in cells and their radiosensitivity.

Comparison of molecular markers of hypoxia and imaging with (60)Cu-ATSM in cancer of the uterine cervix

PURPOSE

To determine if hypoxia-related molecular markers are associated with (60)Cu labeled diacetyl-bis (N4 -methylthiosemicarbazone); ((60)Cu-ATSM) imaging of tumor hypoxia in cervical cancer.

PROCEDURES

Fifteen patients were enrolled in a prospective study and underwent evaluation of tumor hypoxia with positron emission tomography (PET) using (60)Cu-ATSM. (60)Cu-ATSM-PET imaging was compared with the expression of tissue molecular markers, which included vascular endothelial growth factor (VEGF), cyclo-oxygenase-2 (COX-2), epidermal growth factor receptor (EGFR), carbonic anyhdrase IX (CA-9), and apoptotic index.

RESULTS

Six patients had hypoxic tumors determined by (60)Cu-ATSM, and nine had non-hypoxic tumors. The 4-year overall survival estimates were 75% for patients with non-hypoxic tumors and 33% for those with hypoxic tumors (p = 0.04). Overexpression of VEGF (p = 0.13), EGFR (p = 0.05), CA-9 (p = 0.02), COX-2 (p = 0.08), and the presence of apoptosis (p = 0.005) occurred in patients with hypoxic tumors. Cox proportional hazards modeling demonstrated hypoxia as determined by (60)Cu-ATSM to be a significant independent predictor of tumor recurrence (p = 0.0287).

CONCLUSIONS

(60)Cu-ATSM hypoxia was correlated with overexpression of VEGF, EGFR, COX-2, CA-9, an increase in apoptosis, and a poor outcome.

Response to high LET radiation 12C (LET, 295 keV/microm) in M5 cells, a radio resistant cell strain derived from Chinese hamster V79 cells

PURPOSE

To study the effects of 12C-beam of 295 keV/microm (57.24 MeV) on M5 and Chinese hamster V79 cells by using cytogenetic assays like micronuclei (MN) induction, chromosomal aberrations (CA) and apoptosis. Additionally, the relative survival of these two cell lines was tested by the colony forming ability of the cells, with a view to understanding the mechanism of cellular damages that lead to difference in cell survival.

MATERIALS AND METHODS

Confluent cells were irradiated with 12C-beam at various doses using 15UD Pelletron accelerator. Cell survival was studied by the colony forming ability of cells. MN assay was done by fluorescent staining. Different types of chromosomal aberrations in metaphase cells were scored at 12 h after irradiation. Apoptosis was measured at different post irradiation times as detected by nuclear fragmentation and DNA ladder was prepared after 48 h of incubation.

RESULTS

Dose-dependent decrease in surviving fractions was found in both the cell lines. However, the surviving fractions were higher in M5 cells in comparison to V79 cells when exposed to the same radiation doses. On the other hand, induced MN frequencies, CA frequencies and apoptosis percentages were less in M5 cells than V79 cells. Very good correlations between surviving fractions and induced MN frequencies or induced total CA or induced apoptosis percentages were obtained in this study.

CONCLUSIONS

The cell strain M5 showed relatively more radio-resistance to 12C-beam compared to Chinese hamster V79 cells in this study. As the MN formation, CA and apoptosis induction were less in M5 cells as compared to parental V79 cells, the higher cell survival in the former could possibly be attributed to their better repairing ability leading to higher cell survival.

Genotoxic effects in M5 cells and Chinese hamster V79 cells after exposure to 7Li-beam (LET=60 keV/microm) and correlation of their survival dynamics to nuclear damages and cell death

Chinese hamster V79 cell and a cell strain M5, derived from V79 cells and reported to be relatively resistant to gamma-ray, hydrogen peroxide, and N-methyl-N-nitro-N-nitrosoguanidine (MNNG; a potent human carcinogen), were exposed to high LET (7)Li-beam (LET=60 keV/microm) at approximately 90% confluent state in the dose range of 0-1 Gy. Effects of (7)Li-beam exposure on cell survival, micronuclei induction (MN), chromosomal aberrations (CA) and apoptosis were compared in both the cell lines. A dose-dependent decline in survival for both the cell lines was noted, relatively less in M5 cells (mostly p<0.01) indicating greater radio-resistance in this strain. The MN, CA and apoptosis increased in a dose-dependent manner in both V79 and M5 cells. Significant differences in various other parameters between these two cell lines were also noted. The relative intensity of DNA ladder, which is a useful marker for the determination of the extent of apoptosis induction, was much higher in V79 cells. A good correlation between the reduction of the surviving fractions and the increase in frequencies of MN or CA or apoptosis was noted for both the cell lines.

Transfer of siRNA against XIAP induces apoptosis and reduces tumor cells growth potential in human breast cancer in vitro and in vivo

BACKGROUND

Gene targeting using short interfering RNA(siRNA) has become a common strategy to explore gene function because of its prominent efficacy and specificity. It is proven that the application of siRNA technology to gene therapy is effective. In this study, we constructed a siRNA expression plasmid against gene X-linked inhibitor of apoptosis (XIAP), and then used breast cancer cells MCF-7 to assess its functions.

MATERIALS AND METHODS

XIAP siRNA plasmid was constructed using an U6pro vector contained U6 promoter, After the plasmid had been transfected into MCF-7 cells and effected on the cell cycle, the expression change of XIAP was examined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The apoptosis of the transfected cells was analyzed by flow cytometry, and TUNEL method. The in vitro cellular growth activities were assayed by MTT incorporation. Twenty-four nude mice were randomly divided into 3 equal groups and were inoculated with electroinjection of blank plasmid, scrambled nucleotide control (control siRNA), or siRNA against XIAP subcutaneously respectively, then the appearance and size of tumors were observed. Four weeks later the mice were killed and the volumes of tumor were calculated so as to evaluate the therapeutic effects of siRNA against XIAP.

RESULTS

The successful construction of siRNA against XIAP plasmid was identified with sequencing. After the siRNA expression vector was transfected into the MCF-7 cells, the expression of XIAP gene was inhibited significantly (by 90%). The cellular growth activities in the MCF-7 cells transfected with siRNA against XIAP plasmid decreased obviously. The siRNA against XIAP plasmid knocked down XIAP expression in MCF-7 cells obviously, arrested the cell cycle in G1 phase, inhibited cell proliferation significantly, and promoted cell apoptosis in a tendency. TUNEL assay and flow cytometry showed that the classic apoptosis characters of the MCF-7 cells transfected with siRNA against XIAP plasmid manifested an apoptosis rate of 77.2%, significantly higher than those in the control siRNA group and in the blank plasmid group (both p < 0.01). The growth speed and formation rate of xenograft tumor in mice transfected with siRNA against XIAP transfected mice slowed down significantly. By HE staining, a lot of necrotic tissues could be observed in the siRNA against XIAP transfected group, however, there was no similar inhibitive effect in the control siRNA or blank plasmid group.

CONCLUSION

This study represents that MCF-7 transfected cells with siRNA against XIAP remarkably suppress tumor growth and induces apoptosis, both in vitro and in vivo. This novel modality may be a promising tool for cancer therapy.

Cyclooxygenase-2 impairs treatment effects of radiotherapy for cervical cancer by inhibition of radiation-induced apoptosis

PURPOSE

Cyclooxygenase-2 (COX-2) plays a pivotal role in regulation of radiation-induced apoptosis. The aim of this study was to analyze the relationship between COX-2 expression and postradiotherapy outcomes of patients with cervical cancer.

METHODS AND MATERIALS

Biopsy specimens from 47 consecutive patients who had undergone definitive radiotherapy alone or radiotherapy combined with chemotherapy between October 2002 and November 2004 were investigated.

RESULTS

The COX-2 expression rate of the pretreatment samples was 46.1% +/- 21.0%, and the apoptotic index (AI) 1 week after start of radiotherapy was 2.1% +/- 0.9%. There was a significant negative correlation between the pretreatment COX-2 expression and the AI during radiotherapy (r = -0.52, p = 0.0002). Complete response rates were 59% for COX-2-positive patients compared with 80% for COX-2-negative patients (p = 0.12). The 2-year local control rate for COX-2-positive patients was 71.3%, whereas the corresponding rate for COX-2-negative patients was 96.0% (p = 0.06).

CONCLUSIONS

To the best of our knowledge, this is the first report to prove clinically that COX-2 can make cervical squamous cell carcinomas more refractory to radiotherapy by inhibition of radiation-induced apoptosis. Furthermore, expression of COX-2 may be a good indicator to predict local tumor control after radiotherapy. Although long-term results are ultimately needed, the combination therapy of radiotherapy with use of a COX-2 inhibitor could yield improved outcomes for patients with COX-2 expressing cervical cancer.

Prediction value of radiosensitivity of hepatocarcinoma cells for apoptosis and micronucleus assay

AIM

To investigate the prediction value of radiosensitivity of hepatocarcinoma cells for apoptosis and micronucleus assay.

METHODS

Clonogenic assay, flow cytometry, and CB micronuclei assay were used to survey the cell survival rate, radiation-induced apoptosis and micronucleus frequency of hepatocarcinoma cell lines SMMC-7721, HL-7702, and HepG2 after being irradiated by X-ray at the dosage ranging 0-8 Gy.

RESULTS

After irradiation, there was a dose-effect relationship between micronucleus frequency and radiation dosage among the three cell lines (P<0.05). A positive relationship was observed between apoptosis and radiation dosage among the three cell lines. The HepG2 cells had a significant correlation (P<0.05) but apoptosis incidence had a negative relationship with micronucleus frequency. There was a positive relationship between apoptosis and radiation dosage and the correlation between SMMC-7721 and HL-7702 cell lines had a significant difference (P<0.01). After irradiation, a negative relationship between cell survival rate and radiation dosages was found among the three cell lines (P<0.01). There was a positive relationship between cell survival rate and micronucleus frequency (P<0.01). No correlation was observed between apoptosis and cell survival rate.

CONCLUSION

The radiosensitivity of hepatocarcinoma cells can be reflected by apoptosis and micronuclei. Detection of apoptosis and micronuclei could enhance the accuracy for predicting radiosensitivity.

Regulation of p53 and suppression of apoptosis by the soluble guanylyl cyclase/cGMP pathway in human ovarian cancer cells

Dysregulated apoptosis plays a critical role in the development of a number of aberrant cellular processes, including tumorigenesis and chemoresistance. However, the mechanisms that govern the normal apoptotic program are not completely understood. Soluble guanylyl cyclase (sGC) and cyclic guanosine monophosphate (cGMP) promote mammalian cell viability via an unknown mechanism and p53 status is a key determinant of cell fate in human ovarian cancer cells. Whether an interaction exists between these two determinants of cell fate is unknown. We hypothesized that basal sGC activity reduces p53 content and attenuates p53-dependent apoptosis in human ovarian cancer cells. Suppression of sGC activity with the specific inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) lowered cGMP content, and increased p53 protein content and induced apoptosis in three ovarian cancer cell lines, effects which were attenuated by the cGMP analog 8-Br-cGMP and by Atrial Natriuretic Factor, an activator of particulate guanylyl cyclase, which circumvent the inhibition of sGC. ODQ prolonged p53 half-life, induced phosphorylation of p53 on Ser15, and upregulated the p53-dependent gene products p21, murine double minute-2, and the proapoptotic, p53-responsive gene product Bax. ODQ activated caspase-3, and ODQ-induced apoptosis was inhibited by overexpression of X-linked inhibitor of apoptosis Protein. Pretreatment with the specific p53 inhibitor pifithrin or downregulation of p53 using a specific small inhibitory RNA significantly attenuated ODQ-induced apoptosis. Moreover, ODQ-induced upregulation of p21 and Bax and ODQ-induced apoptosis were significantly reduced in a p53 mutant cell line relative to the wild-type parental cell line. Thus, the current study establishes that basal sGC/cGMP activity regulates p53 protein stability, content, and function, possibly by altering p53 phosphorylation and stabilization, and promotes cell survival in part through regulation of caspase-3 and p53.

Intestinal mucositis: the role of the Bcl-2 family, p53 and caspases in chemotherapy-induced damage

Intestinal mucositis occurs as a consequence of cytotoxic treatment through multiple mechanisms including induction of crypt cell death (apoptosis) and cytostasis. The molecular control of these actions throughout the gastrointestinal tract has yet to be fully elucidated; however, they are known to involve p53, the Bcl-2 family and caspases. This review will provide an overview of current research as well as identify areas where gaps in knowledge exist.

Expression of the proapoptotic protein Bid is an adverse prognostic factor for radiotherapy outcome in carcinoma of the cervix

The Bcl-2 family of apoptotic regulators is thought to play an essential role in cancer development and influence the sensitivity of tumour cells to radiotherapy. Bid is an abundantly expressed Bcl-2 family protein playing a central role in various pathways of apoptosis by integrating and converging signals at the mitochondria. The relevance of apoptotic modulation by Bcl-2 and related proteins in tumour development and radiation response for human tumours remains undefined. Therefore, a study was made regarding the expression of Bid in patients with locally advanced cervix carcinoma who received radiotherapy. Bid expression was assessed using immunohistochemistry in pretreatment archival biopsies from 98 patients. The data were correlated with clinicopathologic characteristics and treatment outcome. Pretreatment tumour radiosensitivity data were available for 60 patients. Strong Bid expression was associated with a patient age less than the median of 52 years (P=0.034) and poor metastasis-free survival. In multivariate analysis, after allowing for stage, Bid expression was a significant prognostic factor for both disease-specific and metastasis-free survival (P=0.026). It is concluded that strong tumour Bid expression is associated with poor outcome following radiotherapy regardless of intrinsic tumour cell radiosensitivity, and is adverse prognostic for disease-specific and metastasis-free survival in younger patients.

Heterogeneity of radiation induced apoptosis in Ewing Tumor cell lines characterized on a single cell level

The objective of this study was to investigate heterogeneity of radiation induced apoptosis on a single cell level. Two Ewing tumor cell lines were characterized in vitro before and 24 and 72 h after radiation with 5 Gy by multiparametric flow cytometry. Annexin V, 7-AAD and fluorescence conjugated antibodies that were directed against HLA-ABC, CD11a and CD62L were used. Based on these markers radiation induced apoptosis was quantified, multiple apoptotic subpopulations were identified and a characteristic individual apoptotic profile was characterized. The characterization of HLA-ABC, CD11a and CD62L was informative to detect subpopulations of apoptotic cells. The observed heterogeneity and the identification of multiple apoptotic subpopulations reflect the complexity and diversity of biology of radiation induced cell death. This might be an indication for co-existing apoptotic pathways or it might represent sequential steps of the apoptotic cascade.

Apoptotic index as predictive marker for radiosensitivity of cervical carcinoma: Evaluation of membrane fluidity, biochemical parameters and apoptosis after the first dose of fractionated radiotherapy to patients

BACKGROUND

This study was aimed to develop possible predictive response of cervical carcinoma in stage IIIA and B patients by evaluating the changes in physical parameter, such as, membrane fluidity, biochemical parameters, such as, intracellular calcium, antioxidant enzymes [superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx)] and apoptotic cell death in cervical cancer cells from patients after treating with the first fractionated dose of 2 Gy in radiation therapy protocol.

METHODS

Biopsies of cervical carcinoma patients were collected before and 24h after first fractionated radiation dose of 2 Gy. Cell suspensions and tissue of cervix cancer biopsies were used to measure various physical and biochemical parameters.

RESULTS AND CONCLUSIONS

A negative correlation was found to exist between observed fluidity of membrane/SOD level with the degree of apoptosis in cervical cells. On the other hand, a positive correlation was observed between intracellular calcium level and percent cellular apoptosis. These results suggest that changes in membrane fluidity, SOD and calcium level were involved in the mechanism of radiation induced cervical apoptosis as measured by TUNEL assay. Moreover, apoptotic sensitivity of these cells after the first dose of radiation treatment showed a direct correlation with the radiation treatment outcome in patients after completion of radiotherapy protocol (70 Gy) in the clinic suggesting that apoptotic index may form a basis for prognosis in radiotherapy in stage III cervix cancer patients.

Quantified relationship between cellular radiosensitivity, DNA repair defects and chromatin relaxation: a study of 19 human tumour cell lines from different origin

BACKGROUND AND PURPOSE

There is still confusion in the choice of the molecular assays to predict the radiation response of human cells. The case of tumours appears to be particularly complex, may be because of their instability and heterogeneity. The aim of this study was to investigate quantitatively the relationships between DNA double-strand breaks (DSB) repair, chromatin relaxation and cellular radiosensitivity. Nineteen human tumour cell lines, representing a large spectrum of radiation responses and tissues, were examined.

MATERIALS AND METHODS

Intrinsic radiosensitivity was quantified with surviving fraction at 2 Gy (SF2) as an endpoint. Standard and modified pulsed-field gel electrophoresis techniques were employed to assess DSB repair rate and chromatin relaxation. A cell-free assay was chosen to estimate DSB repair activity, independently of chromatin impairment.

RESULTS AND CONCLUSIONS

Surviving fraction at 2 Gy (SF2) decreases linearly with the amount of unrepaired DSB and the extent of chromatin relaxation: one additional unrepaired DSB per cell or 1% chromatin decondensation produce a loss of about 1.5% surviving fraction. However, all the cell lines did not obey both correlations, suggesting that DSB repair and chromatin impairments contribute separately to increase the severity of DNA damage involved in cell lethality. Four cell lines groups showing different DSB repair and/or chromatin impairments were defined. Cell lines exhibiting both DSB repair defect and chromatin relaxation are the most radiosensitive.

99mTc-HYNIC Annexin-V imaging of primary head and neck carcinoma

In this study, the potential of 99mTc-HYNIC Annexin-V scintigraphy to visualize primary head and neck carcinoma was assessed and compared with computed tomography (CT) findings and histology. Eighteen patients suspected of having primary head and neck carcinoma underwent a spiral CT scan and 99mTc-HYNIC Annexin-V scintigraphy within 1 week of each other, followed by resection of the suspected lesion. Results obtained by CT and scintigraphy were compared vs. histopathology. The diagnosis was primary head and neck carcinoma in 18 patients, accompanied by lymph node involvement in seven patients. 99mTc-HYNIC Annexin-V uptake was identified in five patients on planar images and in 17 patients on tomographic images (single-photon emission computed tomography, SPECT), corresponding to the pathological regions identified by CT. In the remaining patient, CT and 99mTc-HYNIC Annexin-V scintigraphy were false negative. In 11 patients, SPECT and CT scan were concordant, identifying all primary lesions and two sites of lymph node involvement. In the six remaining patients, CT and SPECT accurately identified the primary lesion, but were discordant with regard to the existence of lymph node involvement. In five of six patients, SPECT failed to identify lymph node involvement, whereas CT scan did not. In the remaining patient, CT scan was false positive for lymph node involvement, whereas SPECT was not. In this series, 99mTc-HYNIC Annexin-V allowed for the visualization of all primary head and neck tumours identified by CT scan, but failed to identify most of the sites of lymph node involvement.

The role of hypoxia inducible factor 1 (HIF-1) in hypoxia induced apoptosis

Apoptosis can be induced in response to hypoxia. The severity of hypoxia determines whether cells become apoptotic or adapt to hypoxia and survive. A hypoxic environment devoid of nutrients prevents the cell undergoing energy dependent apoptosis and cells become necrotic. Apoptosis regulatory proteins are delicately balanced. In solid tumours, hypoxia is a common phenomenon. Cells adapt to this environmental stress, so that after repeated periods of hypoxia, selection for resistance to hypoxia induced apoptosis occurs. These resistant tumours probably have a more aggressive phenotype and may have decreased responsiveness to treatment. The key regulator of this process, hypoxia inducible factor 1 (HIF-1), can initiate apoptosis by inducing high concentrations of proapoptotic proteins, such as BNIP3, and can cause stabilisation of p53. However, during hypoxia, antiapoptotic proteins, such as IAP-2, can be induced, whereas the proapoptotic protein Bax can be downregulated. During hypoxia, an intricate balance exists between factors that induce or counteract apoptosis, or even stimulate proliferation. Understanding the regulation of apoptosis during hypoxia and the mechanisms of resistance to apoptosis might lead to more specific treatments for solid tumours.

Concerted regulation of inorganic pyrophosphate and osteopontin by akp2, enpp1, and ank: an integrated model of the pathogenesis of mineralization disorders

Tissue-nonspecific alkaline phosphatase (TNAP) hydrolyzes the mineralization inhibitor inorganic pyrophosphate (PP(i)). Deletion of the TNAP gene (Akp2) in mice results in hypophosphatasia characterized by elevated levels of PP(i) and poorly mineralized bones, which are rescued by deletion of nucleotide pyrophosphatase phosphodiesterase 1 (NPP1) that generates PP(i). Mice deficient in NPP1 (Enpp1(-/-)), or defective in the PP(i) channeling function of ANK (ank/ank), have decreased levels of extracellular PP(i) and are hypermineralized. Given the similarity in function between ANK and NPP1 we crossbred Akp2(-/-) mice to ank/ank mice and found a partial normalization of the mineralization phenotypes and PP(i) levels. Examination of Enpp1(-/-) and ank/ank mice revealed that Enpp1(-/-) mice have a more severe hypermineralized phenotype than ank/ank mice and that NPP1 but not ANK localizes to matrix vesicles, suggesting that failure of ANK deficiency to correct hypomineralization in Akp2(-/-) mice reflects the lack of ANK activity in the matrix vesicle compartment. We also found that the mineralization inhibitor osteopontin (OPN) was increased in Akp2(-/-), and decreased in ank/ank mice. PP(i) and OPN levels were normalized in [Akp2(-/-); Enpp1(-/-)] and [Akp2(-/-); ank/ank] mice, at both the mRNA level and in serum. Wild-type osteoblasts treated with PP(i) showed an increase in OPN, and a decrease in Enpp1 and Ank expression. Thus TNAP, NPP1, and ANK coordinately regulate PP(i) and OPN levels. The hypomineralization observed in Akp2(-/-) mice arises from the combined inhibitory effects of PP(i) and OPN. In contrast, NPP1 or ANK deficiencies cause a decrease in the PP(i) and OPN pools that leads to hypermineralization.

Proliferation to apoptosis ratio as a prognostic marker in adenocarcinoma of uterine cervix

OBJECTIVES

To determine the Mitotic Index (MI), Apoptotic Index (AI), the ratio of the two indices (MI/AI) in normal endocervical glands, adenocarcinoma in situ (AIS) and invasive adenocarcinoma of cervix, and to evaluate the relationship among these indices with various clinicopathological features.

METHODS

The MI, AI and MI/AI ratio in cervical adenocarcinoma were evaluated based on: (1) cell morphology in hematoxylin and eosin-stained sections; (2) immunohistochemical study for Ki67 antigen and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL). Eighty cases of invasive adenocarcinoma and eighteen cases of adenocarcinoma in situ (AIS) adjacent to invasive adenocarcinoma were included. Adjacent normal endocervical epithelium in 26 cases of adenocarcinoma was included as control.

RESULTS

The MI, AI and MI/AI in normal endocervical glands, AIS and invasive carcinomas showed statistically significant differences (P<0.001). A significant positive correlation was found between AI and MI, as assessed by morphological features (P<0.001) and immunohistochemistry (P=0.006). The MI/AI ratio, determined by morphology, significantly correlated with staging (P=0.023) and survival (P=0.0045). Multivariate survival analysis showed that both MI/AI ratio determined by morphology (P<0.001) and stage of tumor (P=0.03) had independent prognostic value in invasive adenocarcinoma.

CONCLUSIONS

Tumor proliferation significantly correlated with apoptotic activity in cervical adenocarcinoma. The MI/AI ratio was an independent prognostic factor associated with patient survival. Histological determination of MI/AI ratio proved to be an economical and potentially useful adjunct in predicting clinical outcome of patients with cervical adenocarcinoma.

Radiolabeled Annexin-V for Monitoring Treatment Response in Oncology

Because of its potential to allow for noninvasive, repetitive, and selective in vivo identification of the site and extent of apoptotic cell death and for monitoring cell death kinetics without the need for invasive biopsy, radiolabeled annexin-V is of major clinical relevance. This paper reviews available preclinical and clinical data on radiolabeled annexin-V pertaining to the domain of monitoring response to radiotherapy and chemotherapy, focusing especially on advantages and drawbacks of the different labeling procedures for the radiolabeling of annexin-V.

High intrinsic apoptosis, but not radiation-induced apoptosis, predicts better survival in rectal carcinoma patients

PURPOSE

An important feature of malignant tumors is the disturbance in the balance between proliferation and cell death. We evaluated the relevance of intrinsic and radiation-induced apoptosis and proliferation for prognosis in rectal cancer patients.

METHODS AND MATERIALS

Patients were selected from a study that randomized for preoperative radiotherapy (RT). Apoptosis and proliferation were scored using specific antibodies in immunohistochemistry. The number of positive cells per square millimeter of carcinoma cells was determined in 98 randomly selected tumors, of which 45 had been irradiated. For the survival analyses, a cohort of 104 patients without positive circumferential resection margins was selected.

RESULTS

In nonirradiated patients, high levels of intrinsic apoptosis correlated with better local control (p = 0.04) and better cancer-specific survival (p = 0.02). RT increased the median amount of apoptosis from 10.8 to 21.5 cells/mm(2) (p = 0.004), but this was not predictive for survival. The amount of proliferative cells was not altered after RT and had no influence on prognosis.

CONCLUSIONS

Intrinsic apoptosis correlated with both local control and cancer-specific survival, but proliferation was not predictive for prognosis. However, although RT increased apoptosis, its prognostic value was lost after RT. This is possibly because in rectal cancer, the proliferative status of tumors is always high and the aggressiveness of the tumor is determined by the number of "spontaneous" apoptotic tumor cells.

Ki-67 immunocytochemistry in liquid based cervical cytology: useful as an adjunctive tool?

AIMS

To test the ability of Ki-67 to detect cytological lesions in a screening setting and its use as a surrogate marker of human papillomavirus (HPV) infection.

METHODS

A study of liquid based cytology, HPV DNA testing by MY09/MY11 consensus polymerase chain reaction (PCR), type specific PCRs, and Ki-67 immunocytochemistry on a randomly selected series of 147 patients.

RESULTS

Comparison of the number of Ki-67 immunoreactive cells/1000 cells in the different cytological groups showed that the HSIL group yielded a significantly higher mean count than did the other groups. The number of Ki-67 immunoreactive cells/1000 cells was significantly higher in HPV-16 positive samples than in samples containing infections with other high risk types. Receiver operating characteristic curves indicated a test accuracy (area under curve) of 0.68, 0.72, and 0.86 for atypical squamous cells of undetermined significance (ASCUS), low grade squamous intraepithelial lesions (LSIL), and high grade squamous intraepithelial lesions (HSIL), respectively. Thresholds for 95% sensitivity were 0.07, 0.08, and 0.15 Ki-67 immunopositive cells/1000 cells for ASCUS, LSIL and HSIL, respectively. The threshold for 95% specificity was 1.9 Ki-67 immunopositive cells/1000 cells.

CONCLUSIONS

Ki-67 immunocytochemistry can be applied to liquid based cytology. The accuracy and diagnostic indices of the test are good when compared with those of other techniques. As part of a panel of screening procedures, it could be used as an adjunct to liquid based cytology to identify HSIL, and as a surrogate marker of HPV-16 infection.

Imbalance between proliferation and apoptosis may be responsible for treatment failure after postoperative radiotherapy in squamous cell carcinoma of the oropharynx

To assess the prognostic value of apoptosis, proliferation and clinical factors in squamous cell carcinoma of the oropharynx after radical surgery and postoperative radiotherapy (RT). Between 1985 and 1995, a total of 82 patients with 84 tumors were entered onto the study. Forty-two primary tumors (50%) involved the tonsils, 23 (27%) the soft palate, and 19 (23%) the base of the tongue. Median age was 52 years (range, 36-73 years). The pT- and pN-categories (UICC 1997) were: T1 (24), T2 (36), T3 (18), T4 (6), N0 (31), N1 (12), N2 (38), NX (8). Histologically clear margins were achieved in all patients by initial surgery. Postoperative RT to the primary and regional lymphatics was given with 60 Gy in 6 weeks and single daily fractions of 2 Gy. The expression of the nuclear Ki-67 labeling index (LI) was investigated by immunostaining using the monoclonal antibody MIB 1 and apoptotic carcinoma cells were identified using the terminal deoxynucleotidyltransferase-(TdT)-mediated dUTP nick end labeling (TUNEL) technique. Median follow-up was 43 months (range, 14-132 months). Overall survival, disease-free survival, and locoregional tumor control rates were 59, 70 and 76% at 5 years. Median values for apoptotic index and Ki-67 labeling were 1.6% (range 0-4.7%), and 20% (range, 0-79%), respectively. Apoptotic index <or=1.6% had a profound negative impact when associated with higher proliferation rates (5-year disease-free survival: 26%) as compared to all other patients with a balance between apoptosis and proliferation (5-year disease-free survival: 66-86%, P=0.003). Additional significant prognostic factors for disease-free survival were: tumor site (tonsils: 83% vs soft palate: 66% vs base of tongue: 49%, P=0.02), duration of RT (<or=47 days: 83% vs >47 days: 55%, P=0.03), Ki-67 LI (<or=20%: 84% vs >20%: 56%, P=0.006). A significant prognostic impact on locoregional control was noted for the duration of RT (P=0.01), tumor site (P=0.02), and the Ki-67 LI (P=0.02). A low apoptotic index together with higher proliferation rates led to unfavourable local control as low as 25% compared to the patients with higher apoptotic index (70-80%, P=0.009). An imbalance between apoptotic index and proliferation may identify patients with squamous cell carcinoma at high risk for local recurrence after surgery and postoperative RT. Prospective observation of these factors in clinical trials is warranted to further elucidate this phenomenon.

Hypoxia-inducible erythropoietin signaling in squamous dysplasia and squamous cell carcinoma of the uterine cervix and its potential role in cervical carcinogenesis and tumor progression

Tissue hypoxia is a characteristic property of cervical cancers that makes tumors resistant to chemo- and radiation therapy. Erythropoietin (Epo) is a hypoxia-inducible stimulator of erythropoiesis. Acting via its receptor (EpoR), Epo up-regulates bcl-2 and inhibits apoptosis of erythroid cells and rescues neurons from hypoxic damage. In addition to human papillomavirus infection, increased bcl-2 expression and decreased apoptosis are thought to play a role in the progression of cervical neoplasia. Using reverse transcriptase-polymerase chain reaction and Western blotting we showed that HeLa and SiHa cervical carcinoma cells and human cervical carcinomas express EpoR, and that hypoxia enhances EpoR expression. Exogenous Epo stimulated tyrosine phosphorylation and inhibited the cytotoxic effect of cisplatin in HeLa cervical carcinoma cells. Using immunohistochemistry, we examined the expression of Epo, EpoR, p16, hypoxia-inducible factor (HIF)-1alpha, and bcl-2 in benign and dysplastic cervical squamous epithelia and invasive squamous cell carcinomas (ISCCs). EpoR expression in benign epithelia was confined to the basal cell layers, whereas in dysplasias it increasingly appeared in more superficial cell layers and showed a significant correlation with severity of dysplasia. Diffuse EpoR expression was found in all ISCCs. Expression of Epo and HIF-1alpha was increased in dysplasias compared to benign epithelia. Focal Epo and HIF-1alpha expression was seen near necrotic areas in ISCCs, and showed correlation in their spatial distribution. Significant correlation was found between expression of EpoR, and p16 and bcl-2 in benign and dysplastic squamous epithelia. Our results suggest that increased expression of Epo and EpoR may play a significant role in cervical carcinogenesis and tumor progression. Hypoxia-inducible Epo signaling may play a significant role in the aggressive behavior and treatment resistance of hypoxic cervical cancers.

Flow cytometric detection of spontaneous apoptosis in human breast cancer using the TUNEL-technique

Microscopic detection of structural alterations is the most reliable method to identify apoptotic cells, which however, does not allow any correlation with cell cycle phases. Discrimination of individual cells within solid human tumors undergoing apoptotic death is possible by flow cytometry where apoptotic cells appear in a hypodiploid sub G0/1-peak as a consequence of partial DNA loss. To refer induction of apoptosis to cell cycle phases we adopted the terminal deoxynucleotidyl transferase nick-end-labelling (TUNEL) technique to flow cytometry which enables the detection of cellular DNA content and DNA fragmentation by multiparametric analysis. One thousand seven hundred human breast carcinomas were screened. In 40 cases (2.3%) of 1700 carcinomas we detected a hypodiploid sub -G0/1 apoptotic peak. The spontaneous apoptotic fractions within individual tumors ranged between 1.5 and 25%. A correlation (r(2)=0.78) was found between apoptotic cells in sub-G0/1-peak measured by DNA-cytometry and TUNEL positive cells measured by multiparametric cytometry, because TUNEL reaction signed also cells with strand breaks. High proliferation indices correspond well (r(2)=0.807) with the increased amount of TUNEL positive cells. Multiparametric flow cytometry for the combined determination of DNA-content and DNA-fragmentation by TUNEL offers not only the advantage of a higher apoptosis sensitivity but also enables the quantification of DNA fragmentation related to any cell cycle phase.

Tumor hypoxia at the micro-regional level: clinical relevance and predictive value of exogenous and endogenous hypoxic cell markers

BACKGROUND AND PURPOSE

Tumor oxygenation is recognized as an important determinant of the outcome of radiotherapy and possibly also of other treatment modalities in a number of tumor types and in particular in squamous cell carcinomas. The hypoxic status of various solid tumors has been related to a poor prognosis due to tumor progression towards a more malignant phenotype, with increased metastatic potential, and an increased resistance to treatment. It has been demonstrated in head and neck cancer that hypoxic radioresistance can be successfully counteracted by hypoxia modifying approaches. The microregional distribution and the level of tumor hypoxia depend on oxygen consumption and temporal and spatial variations in blood supply. It is unclear if severely hypoxic cells can resume clonogenicity when O(2) and nutrients become available again as a result of (treatment related) changes in the tumor microenvironment. Non-terminally differentiated hypoxic cells that are capable of proliferation are important for outcome because of their resistance to radiotherapy and possibly other cytotoxic treatments. Various exogenous and endogenous markers for hypoxia are currently available and can be studied in relation to each other, the tumor architecture and the tumor microenvironment. Use of nitroimidazole markers with immunohistochemical detection allows studying tumor cell hypoxia at the microscopic level. Co-registration with other microenvironmental parameters, such as vascular architecture (vascular density), blood perfusion, tumor cell proliferation and apoptosis, offers the possibility to obtain a comprehensive functional image of tumor patho-physiology and to study the effects of different modalities of cancer treatment.

CONCLUSION

A number of functional microregional parameters have emerged that are good candidates for future use as indicators of tumor aggressiveness and treatment response. The key question is whether these parameters can be used as tools for selection of treatment strategies for individual patients. This requires testing of these markers in prospective randomized clinical trials comparing standard treatment against experimental treatments targeting the relevant microregional constituent.

Chemosensitivity and p53-Bax pathway-mediated apoptosis in patients with uterine cervical cancer

OBJECTIVES

To determine whether and how apoptosis through the p53-Bax pathway affects sensitivity to chemotherapy in cervical cancer.

MATERIALS AND METHODS

Thirty patients with cervical squamous cell carcinoma, who had human papilloma virus (HPV) and underwent neoadjuvant chemotherapy, were entered in the present study. Tumor specimens were obtained before and after chemotherapy. HPV was detected by polymerase chain reaction. The expression of Ki-67, p53, Bax and Bcl-2 proteins was determined by immunohistochemical staining. Apoptotic cells were identified by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labeling method.

RESULTS

Of 30 patients, 18 responded to chemotherapy and 12 did not. The apoptotic index in tumors of responders was significantly higher than in non-responders after chemotherapy. The Ki-67 labeling index (LI) in responders was significantly higher than in non-responders before chemotherapy. Patients with tumors >33% of the LI, which was determined by a receiver operating characteristic curve, had a better survival rate. The incidence of p53 protein expression did not differ between responders and non-responders. After chemotherapy, the expression of Bax protein in responders was more frequent and Bcl-2 protein expression was less frequent than in non-responders.

CONCLUSIONS

Chemosensitivity in cervical cancer may be associated with apoptosis via the p53-Bax pathway.

Nuclear medicine imaging to predict response to radiotherapy: a review

PURPOSE

To review available literature on positron emission tomography (PET) and single photon emission computerized tomography (SPECT) for the measurement of tumor metabolism, hypoxia, growth factor receptor expression, and apoptosis as predictors of response to radiotherapy.

METHODS AND MATERIALS

Medical literature databases (Pubmed, Medline) were screened for available literature and critically analyzed as to their scientific relevance.

RESULTS

Studies on 18F-fluorodeoxyglucose PET as a predictor of response to radiotherapy in head-and-neck carcinoma are promising but need confirmation in larger series. 18F-fluorothymine is stable in human plasma, and preliminary clinical data obtained with this marker of tumor cell proliferation are promising. For imaging tumor hypoxia, novel, more widely available radiopharmaceuticals with faster pharmacokinetics are mandatory. Imaging of ongoing apoptosis and growth factor expression is at a very early stage, but results obtained in other domains with radiolabeled peptides appear promising. Finally, for most of the tracers discussed, validation against a gold standard is needed.

CONCLUSION

Optimization of the pharmacokinetics of relevant radiopharmaceuticals as well as validation against gold-standard tests in large patient series are mandatory if PET and SPECT are to be implemented in routine clinical practice for the purpose of predicting response to radiotherapy.

Surrogate endpoints in cancer drug development

Over the next three years a large number of novel, mechanistically targeted drugs will enter clinical trials for cancer. The remarkable progress in understanding the molecular biology of cancer has provided an enormous range of validated targets for drug discovery. Following lead optimisation and suitable pharmaceutical formulation these compounds have undergone rapid screening in preclinical models. Innovative methods of clinical development are now essential to ensure optimal dose determination and scheduling. The discovery of novel surrogates for efficacy is essential in this fast moving area and requires imaginative partnerships between academic groups and the pharmaceutical industry.