APAF-1 signaling in human melanoma

[Effects of Oxidative Stress on Mitochondrial Functions and Intervertebral Disc Cells]

Intervertebral disc degeneration is widely recognized as one of the main causes of lower back pain. Intervertebral disc cells are the primary cellular components of the discs, responsible for synthesizing and secreting collagen and proteoglycans to maintain the structural and functional stability of the discs. Additionally, intervertebral disc cells are involved in maintaining the nutritional and metabolic balance, as well as exerting antioxidant and anti-inflammatory effects within the intervertebral discs. Consequently, intervertebral disc cells play a crucial role in the process of disc degeneration. When these cells are exposed to oxidative stress, mitochondria can be damaged, which may disrupt normal cellular function and accelerate degenerative changes. Mitochondria serve as the powerhouse of cells, being the primary energy-producing organelles that control a number of vital processes, such as cell death. On the other hand, mitochondrial dysfunction may be associated with various degenerative pathophysiological conditions. Moreover, mitochondria are the key site for oxidation-reduction reactions. Excessive oxidative stress and reactive oxygen species can negatively impact on mitochondrial function, potentially leading to mitochondrial damage and impaired functionality. These factors, in turn, triggers inflammatory responses, mitochondrial DNA damage, and cell apoptosis, playing a significant role in the pathological processes of intervertebral disc cell degeneration. This review is focused on exploring the impact of oxidative stress and reactive oxygen species on mitochondria and the crucial roles played by oxidative stress and reactive oxygen species in the pathological processes of intervertebral disc cells. In addition, we discussed current cutting-edge treatments and introduced the use of mitochondrial antioxidants and protectants as a potential method to slow down oxidative stress in the treatment of disc degeneration.

Withaferin A: A Dietary Supplement with Promising Potential as an Anti-Tumor Therapeutic for Cancer Treatment - Pharmacology and Mechanisms

Cancer, as the leading cause of death worldwide, poses a serious threat to human health, making the development of effective tumor treatments a significant challenge. Natural products continue to serve as crucial resources for drug discovery. Among them, Withaferin A (WA), the most active phytocompound extracted from the renowned dietary supplement Withania somnifera (L.) Dunal, exhibits remarkable anti-tumor efficacy. In this manuscript, we aim to comprehensively summarize the pharmacological characteristics of WA as a potential anti-tumor drug candidate, with the objective of contributing to its further development and the discovery of prospective drugs. Through an extensive review of literature from PubMed, Science Direct, and Web of Science, we have gathered substantial evidence showcasing WA's significant anti-tumor effects against a wide range of cancers in both in vitro and in vivo studies. Mechanistically, WA exerts its anti-tumor influence by inducing cell cycle arrest, apoptosis, autophagy, and ferroptosis. Additionally, it inhibits cell proliferation, cancer stem cells, tumor metastasis, and also suppresses epithelial-mesenchymal transition (EMT) and angiogenesis. Several studies have identified direct target proteins of WA, such as vimentin, Hsp90, annexin II and mFAM72A, while BCR-ABL, Mortalin (mtHsp70), Nrf2, and c-MYB are potential targets of WA. Notwithstanding its remarkable anti-tumor efficacy, there are some limitations associated with WA, including potential toxicity and poor oral bioavailability, which need to be addressed when considering it as an anti-tumor candidate agent. Nevertheless, I given its promising anti-tumor attributes, WA remains an encouraging candidate for future drug development. Unveiling the exact target and comprehensive mechanism of WA's action represents a crucial research direction to pursue in the future.

Cancer and apoptosis: The apoptotic activity of plant and marine natural products and their potential as targeted cancer therapeutics

Cancer is a multifactorial, multi-stage disease, including complex cascades of signaling pathways—the cell growth governed by dysregulated and abrupt cell division. Due to the complexity and multi-regulatory cancer progression, cancer is still a challenging disease to treat and survive. The screening of extracts and fractions from plants and marine species might lead to the discovery of more effective compounds for cancer therapeutics. The isolated compounds and reformed analogs were known as future prospective contenders for anti-cancer chemotherapy. For example, Taxol, a potent mitotic inhibitor discovered from Taxus brevifolia, suppresses cell growth and arrest, induces apoptosis, and inhibits proliferation. Similarly, marine sponges show remarkable tumor chemo preventive and chemotherapeutic potential. However, there is limited research to date. Several plants and marine-derived anti-cancer compounds having the property to induce apoptosis have been approved for clinical trials. The anti-cancer activity kills the cell and slows the growth of cancer cells. Among cell death mechanisms, apoptosis induction is a more profound mechanism of cell death triggered by naturally isolated anti-cancer agents. Evading apoptosis is the major hurdle in killing cancer cells, a mechanism mainly regulated as intrinsic and extrinsic. However, it is possible to modify the apoptosis-resistant phenotype of the cell by altering many of these mechanisms. Various extracts and fractions successfully induce apoptosis, cell-cycle modulation, apoptosis, and anti-proliferative activity. Therefore, there is a pressing need to develop new anti-cancer drugs of natural origins to reduce the effects on normal cells. Here, we’ve emphasized the most critical elements: i) A better understanding of cancer progression and development and its origins, ii) Molecular strategies to inhibit the cell proliferation/Carcino-genesis, iii) Critical regulators of cancer cell proliferation and development, iv) Signaling Pathways in Apoptosis: Potential Targets for targeted therapeutics, v) Why Apoptosis induction is mandatory for effective chemotherapy, vi) Plants extracts/fractions as potential apoptotic inducers, vii) Marine extracts as Apoptotic inducers, viii) Marine isolated Targeted compounds as Apoptotic inducers (FDA Approved/treatment Phase). This study provides a potential therapeutic option for cancer, although more clinical studies are needed to verify its efficacy in cancer chemotherapy.

Jellyfish as an Alternative Source of Bioactive Antiproliferative Compounds

Jellyfish are commonly considered a nuisance for their negative effects on human activities (e.g., fisheries, power plants and tourism) and human health. However, jellyfish provide several benefits to humans and are commonly eaten in eastern countries. Additionally, recent studies have suggested that jellyfish may become a source of high-value molecules. In this study, we tested the effects of the methanolic extracts and enriched fractions, obtained by solid-phase extraction fractionation, from the scyphomedusae Pelagia noctiluca, Rhizostoma pulmo, Cotylorhiza tuberculata and the cubomedusa Caryddea marsupialis on different human cancer cell lines in order to evaluate a potential antiproliferative activity. Our results indicated that fraction C from Caryddea marsupialis-(CM) and C. tuberculata oral arms (CTOA) were the most active to reduce cell viability in a dose-dependent manner. LC/MS based dereplication analyses highlighted that both bioactive fractions contained mainly fatty acids and derivatives, with CM additionally containing small peptides (0.7–0.8 kDa), which might contribute to its higher biological activity. The mechanism of action behind the most active fraction was investigated using PCR arrays. Results showed that the fraction C of CM can reduce the expression of genes involved in apoptosis inhibition in melanoma-treated cells, which makes jellyfish a potential new source of antiproliferative drugs to be exploited in the future.

Upregulation of apoptotic protease activating factor-1 expression correlates with anti-tumor effect of taxane drug

Drug resistance is a multifactorial process involving a variety of mechanisms and genes. Taxane drug class like Docetaxel is not effective for all types' breast cancers and presents a huge clinical challenge. To improve cancer treatment outcome, it is important to distinguish which proteins can kill the cancer cells and whether the expression levels of these proteins affect treatment. Cancer cells are wildly known to be protected from apoptosis, due to low level of apoptotic protease activating factor-1 (Apaf-1) compared with normal cells. Apaf-1 is an essential protein that defines whether cytochrome c released form mitochondria remains stable or degrades. According to this hypothesis, increasing of Apaf-1 expression in MCF7 breast cancer cells was performed and Docetaxel efficacy examined. The immunoassay techniques were used to investigate Apaf-1 and cytochrome c levels, and different apoptosis assay methods applied to better understand the effect of Apaf-1 expression levels in cellular response to apoptotic stimuli by Docetaxel. Our results determined that cytoplasmic cytochrome c level elevated along with increasing Apaf-1 and MCF7 cells were sensitised to Docetaxel, suggesting that loss of Apaf-1 may cause Docetaxel-resistance in breast cancer cells through less apoptosome formation. ROS level increased in cells transfected with Apaf-1 and induced mitochondrial permeability for cytochrome c release, which subsequently promoted apoptosome formation, intrinsic apoptosis and ATP depletion.

Treating MCF7 breast cancer cell with proteasome inhibitor Bortezomib restores apoptotic factors and sensitizes cell to Docetaxel

Chemoresistance is the leading cause of limiting long-term treatment success in cancer cells. Anticancer drugs usually kill cells through apoptosis induction and defects in this signaling pathway lead to chemoresistance. Apoptotic protease activating factor 1 regulates cellular stress evoked by chemotherapeutic agents through facilitating apoptosome assembling but can be degraded by proteasome. This study examined the role of proteasome inhibitor Bortezomib in the cytotoxic effects of Docetaxel on MCF7 cells response and its correlation with Apaf-1 expression level. MTT assay, caspase 3/7 activity assay, propidium iodide staining, adenosine triphosphate and reactive oxygen species amount measurements were utilized to demonstrate the role of Bortezomib in Docetaxel efficacy with and without Apaf-1 overexpressing. Meanwhile, two-dimensional cell migration assay was performed by scratch wound assay. The combination of Docetaxel with Bortezomib was significantly more cytotoxic compared single drug, more effectively delayed cell growth, reduced ATP level and increased ROS production. In Apaf-1 overexpressing, Docetaxel was more efficient in preventing cell migration, however, Docetaxel plus Bortezomib were not significantly effective; and fluorescence images supported the interpretation. Our findings demonstrated MCF7 resistance to Docetaxel is due in part to low Apaf-1 level and Apaf-1 overexpression resulted in the increase of cell susceptibility to Docetaxel stimulus. We assume that proteasome inhibitor may restore apoptotic proteins like Apaf-1 and prevent the degradation of cytosolic cytochrome c released by Docetaxel, consequently triggering intrinsic apoptosis and promoting cancer cell death. Collectively, treating MCF7 breast cells with proteasome inhibitor sensitizes cells to Docetaxel-induced apoptosis and possibly overcomes chemoresistance.

Molecular insights into cancer therapeutic effects of the dietary medicinal phytochemical withaferin A

Despite the worldwide research efforts to combat cancer, it remains a leading cause of death. Although various specific kinase inhibitors already have been approved for clinical cancer treatment, occurrence of intrinsic or acquired resistance and intermittent response over longer periods limits long-term success of single kinase-targeted therapies. In this respect, there is a renewed interest in polypharmaceutical natural compounds, which simultaneously target various hyperactivated kinases involved in tumour-inflammation, angiogenesis, cell survival, proliferation, metastasis and angiogenesis. The dietary medicinal phytochemical withaferin A (WA), isolated from Withaferin somnifera (popular Indian name Ashwagandha), holds promise as a novel anti-cancer agent, which targets multiple cell survival kinase pathways, including IκB kinase/NF-κB, PI3 kinase/protein kinase B/mammalian target of rapamycin and mitogen-activated protein kinase/extracellular signal-regulated kinase amongst others. In this review, we propose a novel mechanism of WA-dependent kinase inhibition via electrophilic covalent targeting of cysteine residues in conserved kinase activation domains (kinase cysteinome), which could underlie its pleiotropic therapeutic effects in cancer signalling.

Targeting apoptosis pathways in cancer and perspectives with natural compounds from mother nature

Although the incidences are increasing day after day, scientists and researchers taken individually or by research group are trying to fight against cancer by several ways and also by different approaches and techniques. Sesquiterpenes, flavonoids, alkaloids, diterpenoids, and polyphenolic represent a large and diverse group of naturally occurring compounds found in a variety of fruits, vegetables, and medicinal plants with various anticancer properties. In this review, our aim is to give our perspective on the current status of the natural compounds belonging to these groups and discuss their natural sources, their anticancer activity, their molecular targets, and their mechanism of actions with specific emphasis on apoptosis pathways, which may help the further design and conduct of preclinical and clinical trials. Unlike pharmaceutical drugs, the selected natural compounds induce apoptosis by targeting multiple cellular signaling pathways including transcription factors, growth factors, tumor cell survival factors, inflammatory cytokines, protein kinases, and angiogenesis that are frequently deregulated in cancers and suggest that their simultaneous targeting by these compounds could result in efficacious and selective killing of cancer cells. This review suggests that they provide a novel opportunity for treatment of cancer, but clinical trials are still required to further validate them in cancer chemotherapy.

Interaction of translationally controlled tumor protein with Apaf-1 is involved in the development of chemoresistance in HeLa cells

Background

Translationally controlled tumor protein (TCTP), alternatively called fortilin, is believed to be involved in the development of the chemoresistance of tumor cells against anticancer drugs such as etoposide, taxol, and oxaliplatin, the underlying mechanisms of which still remain elusive.

Methods

Cell death analysis of TCTP-overexpressing HeLa cells was performed following etoposide treatment to assess the mitochondria-dependent apoptosis. Apoptotic pathway was analyzed through measuring the cleavage of epidermal growth factor receptor (EGFR) and phospholipase C-γ (PLC-γ), caspase activation, mitochondrial membrane perturbation, and cytochrome c release by flow cytometry and western blotting. To clarify the role of TCTP in the inhibition of apoptosome, in vitro apoptosome reconstitution and immunoprecipitation was used. Pull-down assay and silver staining using the variants of Apaf-1 protein was applied to identify the domain that is responsible for its interaction with TCTP.

Results

In the present study, we confirmed that adenoviral overexpression of TCTP protects HeLa cells from cell death induced by cytotoxic drugs such as taxol and etoposide. TCTP antagonized the mitochondria-dependent apoptotic pathway following etoposide treatment, including mitochondrial membrane damage and resultant cytochrome c release, activation of caspase-9, and -3, and eventually, the cleavage of EGFR and PLC-γ. More importantly, TCTP interacts with the caspase recruitment domain (CARD) of Apaf-1 and is incorporated into the heptameric Apaf-1 complex, and that C-terminal cleaved TCTP specifically associates with Apaf-1 of apoptosome in apoptosome-forming condition thereby inhibiting the amplification of caspase cascade.

Conclusions

TCTP protects the cancer cells from etoposide-induced cell death by inhibiting the mitochondria-mediated apoptotic pathway. Interaction of TCTP with Apaf-1 in apoptosome is involved in the molecular mechanism of TCTP-induced chemoresistance. These findings suggest that TCTP may serve as a therapeutic target for chemoresistance in cancer treatment.

Effects of Jianpi Jiedu decoction on tumor growth and Caspase3 expression in HCT116/L-OHP colon cancer xenografts in nude mice

AIM: To observe whether Jianpi Jiedu decoction and oxaliplatin (L-OHP) have a synergistic effect on human colon cancer HCT116/L-OHP xenografts in nude mice and to explore the underlying mechanism.

METHODS: A xenograft tumor model was established using L-OHP-resistant human colon cancer HCT116 cells in nude mice. Mice were randomly divided into a control group, a L-OHP group, a Jianpi Jiedu decoction group, a low dose Jianpi Jiedu decoction plus L-OHP group, and a high dose Jianpi Jiedu decoction plus L-OHP group. During the treatment process, the long and short diameters of tumors were measured to calculate tumor volume according to the formula and depict tumor growth curve. After treatment, the tumor weight was measured to calculate tumor inhibition rate and tumor weight inhibition rate. The expression level of Caspase 3 in tumor xenografts was detected using immunohistochemistry and Western blot.

RESULTS: Tumor volume and tumor weight were significantly lower in the high dose Jianpi Jiedu decoction plus L-OHP group (995.54 mm³ ± 87.26 mm³; 0.85 g ± 0.06 g) and low dose Jianpi Jiedu decoction plus L-OHP group (1318.32 mm³ ± 100.68 mm³; 1.06 g ± 0.07 g) than in the Jianpi Jiedu decoction group (1967.83 mm³ ± 178.83 mm³; 1.71 g ± 0.11 g) and L-OHP group (1698.46 mm³ ± 147.61 mm³; 1.56 g ± 0.12 g) (P < 0.05 or P < 0.01). Tumor inhibition rate and tumor weight inhibition rate were significantly higher in the high dose Jianpi Jiedu decoction plus L-OHP group (55.63%; 56.85%) and low dose Jianpi Jiedu decoction plus L-OHP group (41.25%; 46.19%) than in the Jianpi Jiedu decoction group (12.30%; 13.20%) and L-OHP group (24.31%; 20.81%) (P < 0.05 or P < 0.01). Jianpi Jiedu decoction plus L-OHP significantly increased the expression of Caspase3 protein in tumor xenografts in nude mice compared to other groups (P < 0.05 or P < 0.01).

CONCLUSION: Jianpi Jiedu decoction plus L-OHP can inhibit tumor growth of xenografts in nude mice and increase the efficacy of L-OHP possibly by up-regulating the expression of Caspase 3 to promote apoptosis.

Chemical nature and structure of organic coating of quantum dots is crucial for their application in imaging diagnostics

BACKGROUND

One of the most attractive properties of quantum dots is their potential to extend the opportunities for fluorescent and multimodal imaging in vivo. The aim of the present study was to clarify whether the composition and structure of organic coating of nanoparticles are crucial for their application in vivo.

METHODS

We compared quantum dots coated with non-crosslinked amino-functionalized polyamidoamine (PAMAM) dendrimers, quantum dots encapsulated in crosslinked carboxyl-functionalized PAMAM dendrimers, and silica-shelled amino-functionalized quantum dots. A multimodal fluorescent and paramagnetic quantum dot probe was also developed and analyzed. The probes were applied intravenously in anesthetized animals for visualization of brain vasculature using two-photon excited fluorescent microscopy and visualization of tumors using fluorescent IVIS(®) imaging (Caliper Life Sciences, Hopkinton, MA) and magnetic resonance imaging.

RESULTS

Quantum dots coated with non-crosslinked dendrimers were cytotoxic. They induced side effects in vivo, including vasodilatation with a decrease in mean arterial blood pressure and heart rate. The quantum dots penetrated the vessels, which caused the quality of fluorescent imaging to deteriorate. Quantum dots encapsulated in crosslinked dendrimers had low cytotoxicity and were biocompatible. In concentrations <0.3 nmol quantum dots/kg bodyweight, these nanoparticles did not affect blood pressure and heart rate, and did not induce vasodilatation or vasoconstriction. PEGylation (PEG [polyethylene glycol]) was an indispensable step in development of a quantum dot probe for in vivo imaging, based on silica-shelled quantum dots. The non-PEGylated silica-shelled quantum dots possessed low colloidal stability in high-salt physiological fluids, accompanied by rapid aggregation in vivo. The conjugation of silica-shelled quantum dots with PEG1100 increased their stability and half-life in the circulation without significant enhancement of their size. In concentrations <2.5 nmol/kg bodyweight, these quantum dots did not affect the main physiological variables. It was possible to visualize capillaries, which makes this quantum dot probe appropriate for investigation of mediators of vasoconstriction, vasodilatation, and brain circulation in intact animals in vivo. The multimodal silica-shelled quantum dots allowed visualization of tumor tissue in an early stage of its development, using magnetic resonance imaging.

CONCLUSION

THE PRESENT STUDY SHOWS THAT THE TYPE AND STRUCTURE OF ORGANIC/BIOORGANIC SHELLS OF QUANTUM DOTS DETERMINE THEIR BIOCOMPATIBILITY AND ARE CRUCIAL FOR THEIR APPLICATION IN IMAGING IN VIVO, DUE TO THE EFFECTS OF THE SHELL ON THE FOLLOWING PROPERTIES: colloidal stability, solubility in physiological fluids, influence of the basic physiological parameters, and cytotoxicity.

Protein signatures for survival and recurrence in metastatic melanoma

Patients with melanoma metastatic to regional lymph nodes exhibit a range in tumor progression, survival, and treatment. Current approaches to stratify patients with this stage of disease predominantly involve clinical and histological methods. Molecular classification thus far has focused almost exclusively on genetic mutations. In this study, proteomic data from 69 melanoma lymph node metastases and 17 disease free lymph nodes acquired by histology-directed MALDI imaging mass spectrometry were used to classify tumor from control lymph node and to molecularly sub-classify patients with stage III disease. From these data, 12 survival associated protein signals and 3 recurrence associated signals in the acquired mass spectra were combined to generate a multiplex molecular signature to group patients into either poor or favorable groups for recurrence and survival. Proteins represented in the signature include cytochrome c, s100 A6, histone H4, and cleaved forms of thymosin β-4, thymosin β-10, and ubiquitin. In total over 40 protein signals from the tissue were identified.

Bioinformatic prediction of ultraviolet light mutagenesis sensitivity of human genes and a method for genetically engineering UVB resistance

Living on earth, we are exposed to ultraviolet (UV) light as part of the solar radiation. UVB spectrum light exposure contributes to the development of skin cancer by interacting with pyrimidine pairs to create lesions called cyclobutane pyrimidine dimers. If these lesions are not removed by nucleotide excision repair, they often give rise to C to T transition mutations. Based on these observations, a bioinformatics approach was used to predict the vulnerability of human protein coding genes to UVB induced loss of function mutations. This data was used to evaluate in depth those genes associated with malignant melanoma. In addition, we demonstrate a method of genetically engineering genes that significantly improves resistance to UVB loss of function mutations.

Molecular pathogenesis of cutaneous melanocytic neoplasms

Melanoma is the deadliest form of skin cancer without an effective treatment. An understanding of the genetic basis of melanoma has recently shed light on some of the mechanisms of melanomagenesis. This review explores the major genes involved in familial and sporadic cutaneous melanoma with an emphasis on CDKN2A, CDK4, MC1R, and MAPK pathway targets (e.g., RAS and BRAF), apoptosis regulators (e.g., BCL-2, AKT, and APAF-1), and the tumor-suppressor genes TP53 and PTEN. New directions for therapeutics based on our current knowledge of the genes implicated in melanoma are also discussed.

Apoptosis-induced compensatory proliferation. The Cell is dead. Long live the Cell!

In multi-cellular organisms, activation of apoptosis can trigger compensatory proliferation in surrounding cells to maintain tissue homeostasis. Genetic studies in Drosophila have indicated that distinct mechanisms of compensatory proliferation are employed in apoptotic tissues of different developmental states. In proliferating eye and wing tissues, the initiator caspase Dronc coordinates cell death and compensatory proliferation through the Jun N-terminal kinase and p53. The mitogens Decapentaplegic and Wingless are induced in this process. By contrast, in differentiating eye tissues, the effector caspases DrICE and Dcp-1 activate the Hedgehog signaling pathway to induce compensatory proliferation. In this review, we summarize these findings and discuss how activation of apoptosis is linked to the process of compensatory proliferation. The developmental and pathological relevance of compensatory proliferation is also discussed.

Expression of Apaf-1 and Caspase 9 gene in colorectal cancer and its significance

AIM: To investigate the significance of Apaf-1 and Caspase 9 expression in the carcinoma of large intestine.

METHODS: Real-time quantitative reverse transcription polymerase chain reaction (RQ-RT-PCR) technique was established for detecting Apaf-1 and Caspase 9 mRNA expression in tissues incised from 60 colorectal cancer patients examined by colonoscopy in the third hospital of Wuhan City.

RESULTS: Apaf-1 and Caspase 9 mRNA expression were significantly lower in colorectal cancer tissues than those in the normal tissues (0.561 ± 0.049 vs 0.947 ± 0.077, P < 0.01; 0.412 ± 0.014 vs 0.922 ± 0.062, P < 0.01). The expression levels of Apaf-1 and Caspase 9 mRNA had no marked differences between the normal tissues and cancer-adjacent tissues.

CONCLUSION: Apaf-1 and Caspase 9 gene dysfunction maybe contribute to the development and progression of colorectal cancer.

Pathways of apoptosis in human autosomal recessive and autosomal dominant polycystic kidney diseases

Autosomal dominant polycystic kidney disease (ADPKD) is a major cause of end-stage renal disease in adults. Autosomal recessive (AR) PKD affects approximately 1:20,000 live-born children with high perinatal mortality. Both diseases have abnormalities in epithelial proliferation, secretion, and cell-matrix interactions, leading to progressive cystic expansion and associated interstitial fibrosis. Cell number in a kidney reflects the balance between proliferation and apoptosis. Apoptosis results from extrinsic (ligand-induced, expression of caspase-8) and intrinsic (mitochondrial damage, expression of caspase-9) triggers. Previous studies have suggested a role for apoptosis in PKD cyst formation and parenchymal destruction. Mechanisms underlying apoptosis in human ADPKD and ARPKD were examined by quantitative immunohistochemistry and Western immunoblot analyses of age-matched normal and PKD tissues. Caspase-8 expression was significantly greater in small cysts and normal-appearing tubules than in larger cysts in ADPKD kidneys. Caspase-8 also appeared early in the disease process of ADPKD. In ARPKD, expression of caspase-8 was most pronounced in later stages of the disease and was not confined to a specific cyst size. In conclusion, apoptosis in human ADPKD is an early event, occurring predominantly in normal-appearing tubules and small cysts, and is triggered by an extrinsic factor, but it occurs later in ARPKD.

Time course and spacial distribution of UV effects on human skin in organ culture

Apoptosis plays an important role in eliminating cells from populations when cells have been exposed to UV irradiation and damaged. Studies of cells in culture have provided some details of the mechanisms involved when stress response genes act after exposure to UV irradiation and other environmental stresses. However, little is known about the responses of intact sections of human skin growing in organ culture to UV irradiation. In the work reported here, it was found that the response of organ-cultured human skin after exposure to UV irradiation is different than the response of cultured cells. At wavelengths below 300 nm, the action spectrum obtained from organ-cultured skin samples showed a lower sensitivity than that observed at 300 nm, indicating that the overlying stratum corneum and upper epidermal cell layers had probably caused a selective absorption of incident UV radiation at some wavelengths. At 3 hours after UV irradiation, p53 was phosphorylated at Ser 15 and Ser 46, and accumulated in the cell nuclei, notably after exposure to 280-320 nm wavelengths. Accumulations of Bax, active Caspase-3 and cleaved PARP were detected in apoptotic cells at 24 hours post-exposure, along with a reduction of Bcl-2 levels, notably after exposure to 300-365 nm light. This difference in apoptotic responses may result from the characteristics of the different irradiation wavelengths used, and from details in the skin's structure. The data obtained in this study using an organ-culture system utilized direct measurements of the biological effects of different wavelengths of UV lights.

Distinct mechanisms of apoptosis-induced compensatory proliferation in proliferating and differentiating tissues in the Drosophila eye

In multicellular organisms, apoptotic cells induce compensatory proliferation of neighboring cells to maintain tissue homeostasis. In the Drosophila wing imaginal disc, dying cells trigger compensatory proliferation through secretion of the mitogens Decapentaplegic (Dpp) and Wingless (Wg). This process is under control of the initiator caspase Dronc, but not effector caspases. Here we show that a second mechanism of apoptosis-induced compensatory proliferation exists. This mechanism is dependent on effector caspases which trigger the activation of Hedgehog (Hh) signaling for compensatory proliferation. Furthermore, whereas Dpp and Wg signaling is preferentially employed in apoptotic proliferating tissues, Hh signaling is activated in differentiating eye tissues. Interestingly, effector caspases in photoreceptor neurons stimulate Hh signaling which triggers cell-cycle reentry of cells that had previously exited the cell cycle. In summary, dependent on the developmental potential of the affected tissue, different caspases trigger distinct forms of compensatory proliferation in an apparent nonapoptotic function.

Rationales for expression and altered expression of apoptotic protease activating factor-1 gene in gastric cancer

AIM: To elucidate the relationship between apoptotic protease activating factor-1 (Apaf-1) gene and gastric cancer.

METHODS: Thirty-five postoperative cancer and adjacent normal tissue samples were collected in the present study. Expression of the Apaf-1 gene in these samples was analyzed by semi-quantitative RT-PCR. Loss of heterozygosity (LOH) was used to determine whether there was loss of Apaf-1 gene in domain of 12q22-23 in the samples. Promoter methylation of Apaf-1 gene in the samples was analyzed by methylation specific (MSP) PCR.

RESULTS: The expression of Apaf-1 mRNA in gastric cancer tissue samples was 51%. The LOH frequency of D12S346, D12S1706, D12S327, D12S1657 and D12S393 was 33%, 8%, 58%, 12% and 42%, respectively. Fifty percent LOH was found at two sites and 17% LOH at three sites. Apaf-1 mRNA expression decreased significantly in 13 cases (r_s = 0.487, P = 0.003). The rate of Apaf-1 promoter methylation was 49% in gastric cancer tissue samples and 23% in para-cancerous tissue samples. Promoter methylation occurred significantly in 16 of 18 gastric cancer tissue samples with decreased expression of Apaf-1 mRNA r_s = 0.886, P = 10^-6).

CONCLUSION: The expression of Apaf-1 gene is low in gastric cancer tissues. Methylation of Apaf-1 gene promoter and LOH in domain of 12q22-23 are the main reasons for the expression and altered expression of Apaf-1 gene.