[Expression of caspase 3 and p53 during physiological apoptosis and apoptosis induced by three teratologic agents during early craniofacial development of the mouse embryo]

Effects of extremely low-frequency pulsed electromagnetic fields (ELF-PEMFs) on glioblastoma cells (U87)

The impact of extremely low-frequency pulsed electromagnetic fields (ELF-PEMFs) at various frequencies and amplitudes was investigated on cell cycle, apoptosis and viability of the Glioblastoma Multiforme (GBM) cell line (U87), in vitro. The GBM is a malignant brain tumor with high mortality in humans and poorly responsive to the most common type of cancer treatments, such as surgery, chemotherapy and radiation therapy. U87 cells with five experimental groups (I-V) were exposed to various ELF-PEMFs for 2, 4 and 24 h, as follows: (I) no exposure, control; (II) 50 Hz 100 ± 15 G; (III) 100 Hz 100 ± 15 G; (IV) 10 Hz 50 ± 10 G; (V) 50 Hz 50 ± 10 G. The morphology properties, cell viability and gene expression of proteins involved in cell cycle regulation (Cyclin-D1 and P53) and apoptosis (Caspase-3) were investigated. After 24 h, the cell viability and Cyclin-D1 expression increased in Group II (30%, 45%), whereas they decreased in Groups III (29%, 31%) and IV (21%, 34%); P53 and Caspase-3 elevated only in Group III; and no significant difference was observed in Group V, respectively, compared with the control (p < 0.05). The data suggest that the proliferation and apoptosis of human GBM are influenced by exposure to ELF-PEMFs in different time-dependent frequencies and amplitudes. The fact that some of the ELF-PEMFs frequencies and amplitudes favor U87 cells proliferation indicates precaution for the use of medical devices related to the MFs on cancer patients. On the other hand, some other ELF-PEMFs frequencies and intensities arresting U87 cells growth could open the way to develop novel therapeutic approaches.

The effects of 12C6+ irradiation on cell cycle, apoptosis, and expression of caspase-3 in the human lung cancer cell line h1299

INTRODUCTION

We aimed to investigate the effects of (12)C(6+) irradiation on the cell cycle and apoptosis as well as the associated mechanisms in the human lung cancer cell line H1299.

METHODS

After irradiation with different doses of (12)C(6+) for varying lengths of incubation, the changes in H1299 cells were assayed by flow cytometry and the microculture tetrazolium test. The expression of caspase-3 was detected by immunocytochemistry, western blot, and reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

The G(2)/M phase was blocked after treatment with 1 and 2 Gy at the 12-hour time point, and the most obvious block of G(2)/M occurred after treatment with 2 and 4 Gy at the 24-hour time point in a dose-dependent manner. The apoptosis rate increased with increasing radiation dose and reached a peak after the cells were irradiated with 2 Gy and incubated for 48 hours. In addition, the RT-PCR, western blot, and ICC results showed that irradiation with (12)C(6+) significantly increased the expression of caspase-3 compared with the control group (p<0.05).

CONCLUSIONS

Irradiation of H1299 cells with (12)C(6+) induced apoptosis and significantly inhibited their growth through heavy ion irradiation-mediated activation of the caspase-3 pathway. Our results show that caspase-3 may play an important role in radiation-induced apoptosis through a p53-independent pathway.

HSP110, caspase-3 and -9 expression in physiological apoptosis and apoptosis induced by in vivo embryonic exposition to all-trans retinoic acid or irradiation during early mouse eye development

Apoptosis is an essential physiological process in embryonic development. In the developing eye of vertebrates, three periods of developmental apoptosis can be distinguished: early, intermediate and later. Within the apoptosis pathway, caspases play a crucial role. It has also been shown that HSP110 may have a potential role in apoptosis. The aim of this research was to study the expression of HSP110, caspase-3 and -9 in physiological, retinoic- or irradiation-induced apoptosis during early eye development. Seven pregnant C57Bl/6J mice received 80 mg kg(-1) of all-trans retinoic acid mixed with sesame oil. Seven pregnant NMRI mice received 2 Gy irradiation at the same gestational day. Control mice of both strains (seven mice of each) were not submitted to any treatment. Embryos were harvested at 3, 6, 12 and 24 h after exposition, fixed, dehydrated and embedded. Coronal sections (5 microm) were made. Slide staining occurred alternatively using anti-caspase-3, anti-caspase-9 and anti-HSP110 immunohistochemistry. HSP110 and caspase-3 expression presented similar topographic and chronological patterns, whereas expression of HSP110 was more precocious in retinoic acid-treated embryos. After retinoic exposure, caspase-3- and HSP110-positive cells were increased in the region of the optic vesicle. By contrast, after irradiation, caspase-3- and HSP110-positive cells were noticeably increased in the optic vesicle, peri-optical mesoderm but less in lens placode. HSP110 was expressed before caspase-3. By contrast, caspase-9 was expressed by a very small number of cells in the optic vesicle either under physiological or under teratogenic conditions. Thus, it seems that activation of caspase-9 is dispensable in early eye developmental apoptosis.

Correlation of Hsp110 expression with caspase-3 and -9 during apoptosis induced by in vivo embryonic exposition to retinoic acid or irradiation in early mouse craniofacial development

OBJECTIVE

To analyze the expression and role of three proteins (HSP110, caspase-3 and caspase-9) during craniofacial development.

DESIGN

Seven pregnant C57Bl/6J mice received, by force-feeding at gestation day 9 (E9), 80 mg/kg of all-trans retinoic acid mixed to sesame oil. Seven pregnant NMRI mice received two grays irradiation at the same gestation day. Control mice of both strains (seven mice for each strain) were not submitted to any treatment. Embryos were obtained at various stages after exposition (3, 6, 12 and 24 h), fixed, dehydrated and embedded. Coronal sections (5 microm) were made. Slide staining occurred alternatively using anti-Hsp110, anti-caspase-3 and anti-caspase-9 immunohistochemistry.

RESULTS

Expression of HSP110, caspase-3 and caspase-9 was found in cells of well-known locations of programmed cell death. After retinoic acid exposure, expressions were increased especially in neural crest cells of mandibular and hyoid arches. Quantification of positive cells shows that caspase-9 and Hsp110 were expressed before caspase-3. After irradiation, the expression of the three proteins quickly increased with a maximum 3 h after irradiation. For all three models of apoptosis (physiological, retinoic-induced and irradiation-induced) HSP110 positive cells were more numerous than caspase-3 positive cells. Caspase-3 positive cells were more numerous than caspase-9 positive cells especially in mesectodermal irradiation-induced apoptotic cells.

CONCLUSION

The findings show a potential function of HSP110 in apoptosis during embryo development. Caspase-3-expressing cells are more numerous than cells expressing caspase-9, especially irradiation-induced apoptotic neural crest cells. This suggests that other caspases, still to be identified, may activate caspase-3 in this model.

Teratogen-induced apoptotic cell death: Does the apoptotic machinery act as a protector of embryos exposed to teratogens?

Considerable evidence has been collected demonstrating that many teratogens induce apoptotic cell death in embryonic structures that turn out to be malformed in fetuses and newborns. Apoptosis is a genetically regulated process that is realized by the activation of death and pro-survival signaling cascades, and the interplay between these cascades determines whether the cell exposed to apoptotic stimuli dies or survives. Therefore, there is intense interest in understanding how the apoptotic machinery functions in embryos exposed to teratogens. However, the interpretation of the results obtained remains problematic. The main problem is that excessive embryonic cell death, regardless of its nature, if uncompensated for, ultimately leads to maldevelopment or embryonic death. Therefore, we can easily interpret results when the intensity of teratogen-induced cell death and the severity or incidence of teratogen-induced anomalies directly correlate with each other. However, when teratogen-induced cell death is not followed by the formation of anomalies, a usual explanation is that teratogen-induced apoptotic cell death contributes to the renewal of teratogen-targeted cell populations by promoting the removal of injured cells. It is clear that such an explanation leaves vague the role of the anti-apoptotic signaling mechanism (and, hence, the apoptotic machinery as a whole) with respect to protecting the embryo against teratogenic stress. In this review, we summarize the data from studies addressing the function of the apoptotic machinery in embryos exposed to teratogens, and then we discuss approaches to interpreting the results of these studies. We hypothesize that activation of a proapoptotic signaling in teratogen-targeted cell populations is a necessary condition for an anti-apoptotic signaling that counteracts the process of maldevelopment to be activated. If such a scenario is true, we need to modify our approaches to choosing molecular targets for studies addressing this topic.