Adrenocortical cell deletion: the role of ACTH

Knockdown of Long Noncoding RNA 01124 Inhibits the Malignant Behaviors of Colon Cancer Cells via miR-654-5p/HAX-1

Background

Previous studies have shown that long noncoding RNAs (lncRNAs) play a key role in cancer, including colon cancer (CC). However, the exact role of long noncoding RNA 01124 (LINC01124) in CC and its mechanisms of action remain unknown. In this study, we investigated the functional effects and the possible mechanism of LINC01124 in CC.

Methods

We first determined the expression of LINC01124 in CC tissues (The Cancer Genome Atlas (TCGA) database) and cell lines (quantitative real-time polymerase chain reaction (qRT-PCR)). Functional analysis via Cell Counting Kit-8 (CCK-8), colony formation, cell cycle, wound healing and Transwell assays were performed, and a mechanistic experiment was performed with the western blotting. The function of LINC01124 was also determined in vivo using nude BALB/c mice.

Results

The results showed that LINC01124 was upregulated in CC tissues and cell lines. Functional studies showed that knockdown of LINC01124 significantly suppressed the proliferation, migration, and invasion of colon cancer cells in vitro and in vivo. Subsequent mechanistic experiments indicated that LINC01124 acted as a sponge to suppress microRNA 654-5p, which targeted HAX-1. Downregulation of LINC01124 decreased the expression of HAX-1, and overexpression of the miR-654-5p inhibitor attenuated the sh-LINC01124-induced inhibition of CC cell proliferation, migration, and invasion.

Conclusion

Collectively, this study revealed that the knockdown of LINC01124 inhibited the malignant behaviors of CC via the miR-654-5p/HAX-1 axis, suggesting that LINC01124 might be a therapeutic target for CC treatment.

Over Fifty Years of Life, Death, and Cannibalism: A Historical Recollection of Apoptosis and Autophagy

Research in biomedical sciences has changed dramatically over the past fifty years. There is no doubt that the discovery of apoptosis and autophagy as two highly synchronized and regulated mechanisms in cellular homeostasis are among the most important discoveries in these decades. Along with the advancement in molecular biology, identifying the genetic players in apoptosis and autophagy has shed light on our understanding of their function in physiological and pathological conditions. In this review, we first describe the history of key discoveries in apoptosis with a molecular insight and continue with apoptosis pathways and their regulation. We touch upon the role of apoptosis in human health and its malfunction in several diseases. We discuss the path to the morphological and molecular discovery of autophagy. Moreover, we dive deep into the precise regulation of autophagy and recent findings from basic research to clinical applications of autophagy modulation in human health and illnesses and the available therapies for many diseases caused by impaired autophagy. We conclude with the exciting crosstalk between apoptosis and autophagy, from the early discoveries to recent findings.

Death of adrenocortical cells during murine acute T. cruzi infection is not associated with TNF-R1 signaling but mostly with the type II pathway of Fas-mediated apoptosis

Earlier studies from our laboratory demonstrated that acute experimental Trypanosoma cruzi infection promotes an intense inflammation along with a sepsis-like dysregulated adrenal response characterized by normal levels of ACTH with raised glucocorticoid secretion. Inflammation was also known to result in adrenal cell apoptosis, which in turn may influence HPA axis uncoupling. To explore factors and pathways which may be involved in the apoptosis of adrenal cells, together with its impact on the functionality of the gland, we carried out a series of studies in mice lacking death receptors, such as TNF-R1 (C57BL/6-^{Tnfrsf1a tm1Imx} or TNF-R1^-/-) or Fas ligand (C57BL/6 Fas-deficient lpr mice), undergoing acute T. cruzi infection. Here we demonstrate that the late hypercorticosterolism seen in C57BL/6 mice during acute T. cruzi infection coexists with and hyperplasia and hypertrophy of zona fasciculata, paralleled by increased number of apoptotic cells. Apoptosis seems to be mediated mainly by the type II pathway of Fas-mediated apoptosis, which engages the mitochondrial pathway of apoptosis triggering the cytochrome c release to increase caspase-3 activation. Fas-induced apoptosis of adrenocortical cells is also related with an exacerbated production of intra-adrenal cytokines that probably maintain the late supply of adrenal hormones during host response. Present results shed light on the molecular mechanisms dealing with these phenomena which are crucial not only for the development of interventions attempting to avoid adrenal dysfunction, but also for its wide occurrence in other infectious-based critical illnesses.

Nesfatin-1 inhibits proliferation and enhances apoptosis of human adrenocortical H295R cells

NUCB2/nesfatin and its proteolytically cleaved product nesfatin-1 are recently discovered anorexigenic hypothalamic neuroproteins involved in energy homeostasis. It is expressed both centrally and in peripheral tissues, and appears to have potent metabolic actions. NUCB2/nesfatin neurons are activated in response to stress. Central nesfatin-1 administration elevates circulating ACTH and corticosterone levels. Bilateral adrenalectomy increased NUCB2/nesfatin mRNA levels in rat paraventricular nuclei. To date, studies have not assessed the effects of nesfatin-1 stimulation on human adrenocortical cells. Therefore, we investigated the expression and effects of nesfatin-1 in a human adrenocortical cell model (H295R). Our findings demonstrate that NUCB2 and nesfatin-1 are expressed in human adrenal gland and human adrenocortical cells (H295R). Stimulation with nesfatin-1 inhibits the growth of H295R cells and promotes apoptosis, potentially via the involvement of Bax, BCL-XL and BCL-2 genes as well as ERK1/2, p38 and JNK1/2 signalling cascades. This has implications for understanding the role of NUCB2/nesfatin in adrenal zonal development. NUCB2/nesfatin may also be a therapeutic target for adrenal cancer. However, further studies using in vivo models are needed to clarify these concepts.

Expression of HAX-1 in colorectal cancer and its role in cancer cell growth

Colorectal cancer (CRC) is one of the most common types of cancer worldwide. Hematopoietic cell-specific protein 1-associated protein X-1 (HAX-1) has been found to be involved in several types of cancer. However, the role of HAX-1 in CRC remains to be elucidated. The aim of the present study was to investigate whether the expression of HAX-1 is associated with the progression of CRC, and to determine the effects of HAX-1 on the apoptosis and proliferation of CRC cells. Tumor tissues and adjacent noncancerous tissues were collected from 60 patients with CRC, following the provision of informed consent. The expression levels of HAX-1 and the association with clinical and pathological characteristics were then analyzed. The expression levels of HAX-1 were significantly higher in the cancerous tissues from the patients with CRC, particularly in tissues of an advanced stage of cancer. In addition, HAX-1 expression was associated with malignant progression and poor prognosis. Furthermore, SW480 CRC cells, overexpressing HAX-1, exhibited increased resistance to camptothecin in vitro, and promoted proliferation in vitro and in vivo. By contrast, HAX-1 knockdown significantly decreased the proliferation. In addition, the expression levels of ki-67 and phosphorylatedakt were inhibited following HAX-1 knockdown. In conclusion, the expression levels of HAX-1 were increased in cancerous tissue from patients with CRC, and were associated with progression of the disease. These results suggested that HAX-1 may contribute to chemotherapy resistance and malignant progression in CRC.

Ion channels and apoptosis in cancer

Humans maintain a constant cell number throughout their lifespan. This equilibrium of cell number is accomplished when cell proliferation and cell death are kept balanced, achieving a steady-state cell number. Abnormalities in cell growth or cell death can lead to an overabundance of cells known as neoplasm or tumours. While the perception of cancer is often that of an uncontrollable rate of cell growth or increased proliferation, a decrease in cell death can also lead to tumour formation. Most cells when detached from their normal tissue die. However, cancer cells evade cell death, tipping the balance to an overabundance of cell number. Therefore, overcoming this resistance to cell death is a decisive factor in the treatment of cancer. Ion channels play a critical role in cancer in regards to cell proliferation, malignant angiogenesis, migration and metastasis. Additionally, ion channels are also known to be critical components of apoptosis. In this review, we discuss the modes of cell death focusing on the ability of cancer cells to evade apoptosis. Specifically, we focus on the role ion channels play in controlling and regulating life/death decisions and how they can be used to overcome resistance to apoptosis in the treatment of cancer.

Epimedium flavonoids counteract the side effects of glucocorticoids on hypothalamic-pituitary-adrenal axis

Our previous studies demonstrated that the epimedium herb, when simultaneously used with GCs, counteracted suppressive effects of GCs on the HPA axis without adverse influence on the therapeutic action of GCs. Here, total flavones were extracted from the epimedium flavonoids (EFs) and then used to investigate whether EFs provide protective effects on the HPA axis. We found that GCs induced a significant decrease in body weight gain, adrenal gland weight gain, and plasma adrenocorticotropin (ACTH) and corticosterone levels. After treatment with EFs, body weight gain, adrenal gland weight gain, and plasma corticosterone level were significantly restored, whilst plasma ACTH level was partially elevated. EFs were also shown to promote cell proliferation in the outer layer of adrenal cortex and to enhance the migration of newly divided cells toward the inner layer. To elucidate the underlying mechanisms, the mRNA expression of insulin-like growth factor II (IGF-II) was measured, and EFs significantly upregulated IGF-II expression. Our results indicated that EFs counteract the suppression of the HPA axis induced by GCs. This may involve both the ACTH and IGF-II pathways and thereby promote regeneration of the adrenal cortex suggesting a potential clinical application of EFs against the suppressive effects of GCs on the HPA axis.

Lesions of the adrenal cortex

CONTEXT

In surgical pathology practice adrenal cortical tumors are rare. However, in autopsy series adrenal cortical nodules are found frequently. These are now being identified more commonly in life when the abdomen is scanned for other disease. It is important to differentiate between benign and malignant lesions as adrenal cortical carcinoma is an aggressive tumor. Molecular genetic investigations are providing new information on both pathogenesis of adrenal tumors and basic adrenal development and physiology.

OBJECTIVE

To provide an overview of current knowledge on adrenal cortical development and structure that informs our understanding of genetic diseases of the adrenal cortex and adrenal cortical tumors.

DATA SOURCES

Literature review using PubMed via the Endnote bibliography tool.

CONCLUSIONS

The understanding of basic developmental and physiologic processes permits a better understanding of diseases of the adrenal cortex. The information coming from investigation of the molecular pathology of adrenal cortical tumors is beginning to provide additional tests for the assessment of malignant potential in diagnosis but the mainstay remains traditional histologic analysis.

A study of physiologic angiogenesis in the human using the dental pulp as an in vivo model

With the commonly used in vivo animal models of angiogenesis, direct extrapolation of results to the human is not possible. The results presented from this study exemplify various phases of angiogenesis, from cell migration to apoptosis. This supports the use of the dental pulp of the developing human tooth as a viable model of in vivo physiologic angiogenesis.

Pro-opiomelanocortin peptides and the adrenal gland

The adrenal gland regulates a number of essential biological functions through production of steroids and catecholamines. Pro-opiomelanocortin (POMC)-derived peptides have been implicated in all aspects of generating, maintaining, and functioning of the adrenal glands. An appreciation for the roles of POMC-derived peptides with respect to the adrenal has been gained from experiments in vitro, and in vivo in different animal models which surgically, pharmacologically, or genetically decrease or increase the amount of POMC peptides available. We recently produced a mouse model with a deletion of the entire coding region of the POMC gene, thus lacking all POMC-derived peptides, from all sources, and at all times. Here we will summarize and discuss the results of traditional in vivo studies on the role of POMC peptides in adrenal development, maintenance, and function in the context of findings in a mouse model genetically lacking all POMC-derived peptides.

Microscopic study of cell death in the adrenal glands of mouse and chick embryos

Dying cells of both chromaffin and cortical cell types were found scattered throughout the adrenal gland of 14-18 day mouse embryos and 17-19 day chick embryos. The ultrastructural appearance of these dying cells was unlike that of cells undergoing apoptosis and there was no evidence of macrophages or other phagocytes removing these cells from the adrenal. Possible morphogenetic functions of cell death in the developing adrenal are discussed.

Age-Related Effects of Dexamethasone Administration in Adrenal Zona Reticularis

Suppression of adrenocorticotropic hormone results in reduced adrenal steroid output, adrenocortical cell atrophy, and apoptosis in young rats. To verify such effects during aging, dexamethasone was injected into rats for 3 days at five different ages; at day 4, adrenals and blood were collected for morphologic and corticosterone assay. Adrenal structure was similar at all ages, but in dexamethasone-injected animals there were ultrastructural features of apoptosis and a higher percentage of TUNEL and caspase-3-labeled nuclei and cytoplasm; their corticosterone decreased significantly. In both groups, there was age-related decrease in the percentage of apoptotic cells, significant only in dexamethasone-injected rats. The data suggest that aged adrenocortical cells are less susceptible to the lack of adrenocorticotropic hormone (ACTH), possibly as a result of their decreased functional ability.

Development, maintenance, and function of the adrenal gland in early postnatal proopiomelanocortin-null mutant mice

Adult mouse mutants homozygous for an engineered proopiomelanocortin (POMC)-null allele lack macroscopically distinct adrenal glands and circulating adrenal hormones. To understand the basis for this adrenal defect, we compared the development of adrenal primordia in POMC-null mice and littermate controls. POMC-null mutant mice are born with adrenal glands that are morphologically indistinguishable from those of their wild-type littermates. However, in mutants adrenal cells fail to proliferate postnatally and adrenals atrophy until they have disappeared macroscopically in the adult. While present, mutant adrenals are differentiated as evidenced by the presence of enzymes for the final steps in the synthesis of corticosterone, aldosterone, and catecholamines. However, in contrast to adrenals of wild-type littermates, adrenals of POMC-null mutants do not produce corticosterone, not even in response to acute stimulation with exogenous ACTH. They do produce aldosterone; however, it is produced at reduced levels correlating with adrenal size. Transplantation of POMC-null mutant adrenals to adrenalectomized wild-type littermates results in adrenals with normal morphology and production of both corticosterone and aldosterone. These findings demonstrate that POMC peptides are not required for prenatal adrenal development and that POMC peptides in addition to ACTH are required for postnatal proliferation and maintenance of adrenal structures capable of producing both glucocorticoids and mineralocorticoids.

Macrophages of the Adrenal Cortex: A Morphological Study of the Effects of Aging and Dexamethasone Administration

Macrophages are present throughout the adrenal cortex, particularly in the deeper layers. They locate next to parenchyma cells, which secrete glucocorticoids under the regulation of the pituitary adrenocorticotropic hormone (ACTH). Blockade of ACTH secretion is followed by adrenocortical cell atrophy and apoptosis, an effect likely to cause an increase in local macrophage number and phagocytic activity. The purpose of the current study was to verify this effect and ascertain its age-related variation after ACTH blockade. Male rats at five different ages ranging from 2 to 24 months were divided into two groups, which were injected with dexamethasone phosphate or saline for 3 days. The adrenals were processed for morphological and morphometric study. The age-related increase in macrophage number seen in a survey of the sections was confirmed in the quantitative study: a significant increase in volume density (Vv), numerical density (Nv), and cell volume was found in both groups; Vv and Nv were higher in treated rats. These findings in the deeper layers of the cortex suggest a continuous process of phagocytosis, likely of parenchyma dead cells or their debris, which increases further after ACTH blockade. An additional modulatory effect of macrophages also may occur because of their secretory role.

DAX1 and its network partners: exploring complexity in development

DAX1 encoded by NR0B1, when mutated, is responsible for X-linked adrenal hypoplasia congenita (AHC). AHC is due to failure of the adrenal cortex to develop normally and is fatal if untreated. When duplicated, this gene is associated with an XY sex-reversed phenotype. DAX1 expression is present during development of the steroidogenic hypothalamic-pituitary-adrenal-gonadal (HPAG) axis and persists into adult life. Despite recognition of the crucial role for DAX1, its function remains largely undefined. The phenotypes of patients and animal models are complex and not always in agreement. Investigations using cell lines have proved difficult to interpret, possibly reflecting cell line choices and their limited characterization. We will review the efforts of our group and others to identify appropriate cell lines for optimizing ex vivo analysis of NR0B1 function throughout development. We will examine the role of DAX1 and its network partners in development of the hypothalamic-pituitary-adrenal/gonadal axis (HPAG) using a variety of different types of investigations, including those in model organisms. This network analysis will help us to understand normal and abnormal development of the HPAG. In addition, these studies permit identification of candidate genes for human inborn errors of HPAG development.

The roles of apoptosis and mitosis in atrophy of the rat sublingual gland

The roles of apoptosis and mitosis of acinar and duct cells in the atrophy of the sublingual gland of rat induced by double duct ligation was investigated using immunohistochemistry for proliferating cell nuclear antigen (PCNA), terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick end labeling (TUNEL), and transmission electron microscopy (TEM). Many PCNA-positive duct cells were observed 3 days after duct ligation, and the numbers decreased thereafter. At 3 and 5 days, several TUNEL-positive acinar cells were observed and typical apoptotic acinar cells were identified by TEM. Necrotic acinar cells were also observed ultrastructurally. After 7 days, there were few acini but many ducts, as well as many structures representing transition from acinus to duct. These observations demonstrate that acinar cell loss by apoptosis and duct cell proliferation by mitosis occur in atrophic sublingual glands as well as in other atrophic salivary glands. In addition, it appears that the transition from acinar to duct cell and the necrosis of acinar cells play important roles in the atrophy of the sublingual gland.

History of the events leading to the formulation of the apoptosis concept

Histological studies of ischaemic liver injury performed between 1962 and 1964 distinguished two types of cell death: classical necrosis, and a process involving conversion of scattered cells into small round masses of cytoplasm that often contained specks of condensed nuclear chromatin. Enzyme histochemistry demonstrated rupture of lysosomes in the former, but preservation of lysosomes in the latter. Similar small round masses were also observed sparsely in normal liver. Electron microscopy showed that the small round bodies resulted from cellular condensation and budding, that they were bounded by membranes and contained intact organelles, and that they were phagocytosed and digested by resident tissue cells, including epithelial cells. In work done in association with Jeffrey Searle, the process was found to occur spontaneously in a variety of malignant tumours and to be enhanced in squamous cell carcinomas of skin responding to radiotherapy. During 1971-1972, I collaborated with Andrew Wyllie and Alastair Currie while on sabbatical leave in Scotland. The newly defined type of cell death was shown to be regulated by hormones in the adrenal cortex and in breast carcinomas. Further, review of published electron micrographs of the cell death known to play an essential role in normal development revealed the same morphological pattern. We proposed that this distinctive phenomenon subserves a general homoeostatic function and suggested it be called apoptosis.

Identification of two novel ACTH-responsive genes encoding manganese-dependent superoxide dismutase (SOD2) and the zinc finger protein TIS11b [tetradecanoyl phorbol acetate (TPA)-inducible sequence 11b]

ACTH is the major trophic factor regulating and maintaining adrenocortical function, affecting such diverse processes as steroidogenesis, cell proliferation, cell migration, and cell survival. We used differential display RT-PCR to identify genes that are rapidly induced by ACTH in the bovine adrenal cortex. Of 42 PCR products differentially amplified from primary cultures of bovine adrenocortical cells treated with 10 nM ACTH, six identified mRNAs that were confirmed by Northern blot analysis to be induced by ACTH. Four of these amplicons encoded noninformative repetitive sequences. Of the other two sequenced amplicons, one encoded a partial sequence for mitochondrial manganese-dependent superoxide dismutase (SOD2), an enzyme that is likely to protect adrenocortical cells from the cytotoxic effects of radical oxygen species generated during steroid biosynthesis. The second was identified as TIS11b (phorbol-12-myristate-13-acetate-inducible sequence 11b)/ERF-1/cMG, a member of the CCCH double-zinc finger protein family. SOD2 induction by ACTH was independent of extracellular steroid concentration or oxidative stress. SOD2 and TIS11b mRNA expressions were rapidly induced by ACTH, reaching a maximal level after 8 h and 3 h of treatment, respectively. These ACTH effects were mimicked by forskolin but appeared independent of cortisol secretion. Upon ACTH treatment, induction of TIS11b expression closely followed the previously characterized peak of vascular endothelial growth factor (VEGF) expression. Transfection of a TIS11b expression plasmid into 3T3 fibroblasts induced a decrease in the expression of a reporter gene placed upstream of the VEGF 3'-untranslated region, indicating that TIS11b may be an important regulator of VEGF expression through interaction with its 3'-untranslated region.

Lessons from CRH knockout mice

Corticotropin-releasing hormone (CRH), the major regulator of hypothalamic-pituitary-adrenal (HPA) axis, has a wide spectrum of actions within the central nervous system and the periphery. The development and use of Crh knockout mice (Crh-/-) has been an important tool for addressing the physiologic and pathologic roles of CRH. This review describes the generation and characterization ofCrh -deficient mice as well as the use of these mice to study the role of CRH in maternal and fetal HPA axes development and in the regulation of the adult HPA axis and behavior. The review concludes with information about recently discovered CRH-related peptides and their possible roles in some of the functions thought initially to be mediated by CRH.

The effect of drugs and toxins on the process of apoptosis

In this review we examine the modifying effect of specific drugs on apoptosis. Apoptosis is a type of cell death prevalent during many physiological and pathological conditions, consisting of several steps, namely, initiating stimuli, transduction pathways, effector mechanisms, nuclear fragmentation, and phagocytosis. Pharmacological substances such as glucocorticoids can either induce or inhibit the process of apoptosis in various cells depending on the type of drug and its concentration. Understanding the mechanisms of interaction of drugs with cells undergoing apoptosis could encourage novel therapeutic approaches to human diseases in which apoptosis has a critical role.

Fetal fetuin selectively induces apoptosis in cancer cell lines and shows anti-cancer activity in tumor animal models

An apoptosis-inducing protein with molecular weight of 60 kDa has been purified from fetal bovine serum. The N-terminal amino acid sequence of this protein (e.g. I-P-L-D-P-V-A-G-Y-K) reveals that it is bovine fetuin, a fetal protein functioning to control embryogenesis. The apoptosis-inducing activity of fetuin is totally dependent on zinc. Depletion of zinc ion from fetuin or substitution of zinc ion by barium ion completely abolished the apoptosis-inducing activity of fetuin. Interestingly, while the fetuin isolated from fetal serum selectively induces apoptosis in cancer without affecting normal cells, the fetuin isolated from mature serum is completely inactive. This suggests that the biological activity of fetuin is under developmental regulation. In vivo, tumor animal model studies showed that fetuin enhanced survival by up to 141% in P388 leukemia animal model in mice. Fetuin was also found to inhibit prostate cancer formation in a PC-3 prostate cancer model in mice.

Opposite effects of dexamethasone and ACTH on the adrenal cortex response to ethane dimethanesulphonate (EDS)

Recently we have reported that ethane dimethane-sulphonate (EDS), the Leydig cell cytotoxin, caused marked atrophy of the adrenal cortex of adult male rats. The aim of this work was to examine whether a 9-day treatment with dexamethasone (0.25 mg/kg/d) or ACTH (40 IU/kg/d), which started 4 days prior to administration of a single dose of EDS (75 mg/kg), influenced the response of the inner adrenocortical zones to the toxin. On day 15 after administration of EDS, adrenal weight was significantly decreased in saline treated rats, but glandular and serum corticosterone levels were not altered. In dexamethasone-suppressed rats, the effect of EDS was augmented; an additional decrease in adrenal weight was accompanied by reduced adrenal and serum corticosterone levels. In ACTH-treated animals EDS was ineffective. These results demonstrate that the deleterious effects of EDS on rat adrenal cortex can be prevented by ACTH and potentiated by dexamethasone.

Apoptosis: mechanisms and clinical implications

The balance between cell survival and death is under tight genetic control. A multiplicity of extracellular signals and intracellular mediators is involved in maintaining this balance. When the cell is exposed to physical, biochemical or biological injury, or deprived of necessary substances, it activates a series of stress-response genes. With minimal insults, the cell may recover. With greater insults, single cell death, or apoptosis, results; the cell dies and is recycled to its neighbours. If the insult overwhelms a large number of cells then necrosis ensues, with an accompanying inflammatory response. Dysregulation of the controlling mechanisms of this system results in disease. Deficient apoptosis is associated with cancer, auto-immunity and viral infections. Excessive apoptosis is associated with ischaemic heart disease, stroke, neurodegenerative disease, sepsis and multiple organ dysfunction syndrome. There are myriad therapeutic options unfolding as understanding is gained of apoptosis and its control.

Cell loss in isolated human islets occurs by apoptosis

Purified islet allografts have largely failed to maintain long-term glucose homeostasis in human recipients, and the reasons for this are unclear. It is noteworthy, however, that islet isolation destroys or removes cellular and noncellular elements of the pancreas that could play an important role in supporting islet survival. The purpose of this study was to determine whether human islet isolation leads to the induction of programmed cell death. Human islets were enzymatically isolated from cadaveric donor pancreata using Liberase or Collagenase P, purified over a discontinuous BSA gradient, then cultured in RPMI 1640 at 37 degrees C in 5% CO2 for < or = 7 days. Islets were examined daily by routine histology and immunocytochemistry for islet hormones, DNA fragmentation [cell death; enzyme-linked immunosorbent assay (ELISA) and TUNEL assay] and for transglutaminase (TG) activity, two indicators of apoptosis. TG activity and DNA fragmentation increased by 1,000% and 1,890%, respectively (p < 0.05) This corresponded to the appearance of pyknotic nuclei on light microscopy, the presence of apoptotic bodies on electron microscopy, and the demonstration of TUNEL-positive cells. These were present primarily in a distribution that corresponded to the insulin-immunoreactive cells. At 5 days, 31.4 +/- 2.2% of islet cells were TUNEL positive. In summary, apoptosis of islet cells appears soon after islet isolation, and involves primarily the beta cell. This is the first report of apoptosis of islet cells after human islet isolation. The loss of beta-cell mass could be implicated in the failure of islet transplantation and merits further investigation.

A specific inhibitor of apoptosis decreases tissue injury after intestinal ischemia-reperfusion in mice

PURPOSE

Apoptosis is a stereotypical pathway of cell death that is orchestrated by a family of cysteine endoproteases called caspases. This study examined the effect of apoptosis inhibition with a specific caspase inhibitor on murine intestinal viability after ischemia-reperfusion (IR).

METHODS

C57Bl6 X SV129 mice underwent segmental small bowel ischemia by vascular isolation of 10 cm of terminal ileum. In separate experiments, the ischemic time was varied from 30 to 130 minutes with a reperfusion interval of 6 hours. The degree of small bowel injury was quantified from 1 to 5 (increasing severity) by standardized, blinded histologic grading. The degree of apoptosis was assessed with a specific assay (terminal deoxyamcleotydil transferase-mediated deoxyuridine triphosphate nick end labeling [TUNEL]) and quantified by calculating the apoptotic index (apoptotic cells/10 high-power fields). To evaluate for activation of interleukin-1beta converting enzyme we measured tissue mature interleukin-1beta levels using a specific enzyme-linked immunosorbent assay. To evaluate the effect of apoptosis inhibition on intestinal viability after IR, mice received 3.0 mg of the caspase inhibitor ZVAD (N-benzyloxycarbonyl Val-Ala-Asp-Ome-fluoromethylketone) subcutaneously before and after IR in five divided doses (n = 11), the same dose of ZFA (N-benzyloxycarbonyl Phe-Ala fluoromethylketone), a structurally similar molecule with no anticaspase activity (n = 9), or sham operation (n = 6).

RESULTS

A linear relationship existed between ischemic interval and histologic grade (r = 0.69, P <.006). Increasing the ischemic interval from 0 to 50 minutes was associated with a fivefold increase in apoptotic index (P =.05). Ischemic bowel was measured to have an average of 57.3 +/- 7.8 pg/mL whereas normal bowel had an average of 1.8 +/- 0.5 pg/mL of mature interleukin-1beta present. Mice tolerated multiple injections of ZVAD and ZFA without signs of toxicity. Animals treated with ZVAD (apoptosis inhibitor) had little injury after 50 minutes of ischemia and 6 hours of reperfusion (injury grade 1.8) compared with sham controls (injury grade 1.2, P =.7) and had significantly less injury than mice treated with ZFA (placebo) (injury grade 3.0, P <.006).

CONCLUSIONS

Increasing ischemic interval in a segmental small bowel murine IR model is associated with increased histologic injury and augmented apoptosis as evidenced by increased TUNEL staining and interleukin-1beta converting enzyme activation. Inhibition of apoptosis with a specific caspase inhibitor significantly diminishes the degree of small bowel injury.

Tissue inhibitor of metalloproteinase-2 (TIMP-2) expression is strongly induced by ACTH in adrenocortical cells

Besides its acute and chronic effects on corticosteroid synthesis, the pituitary adrenocorticotropic hormone (ACTH) regulates diverse adrenocortical biological functions including the synthesis of a number of mitochondrial, cytoplasmic, and secreted proteins. ACTH-induced secreted proteins are candidates to act as local extracellular relays of the hormone in either an autocrine or a paracrine manner. In the present study, we report that stimulation of primary cultures of bovine adrenocortical (BAC) fasciculata cells with 10 nM ACTH for 24 h results in a mean 8 +/- 4-fold induction of the synthesis of a secreted protein presenting an apparent Mr of 21 kDa. Peptide microsequencing and Western blotting allowed us to identify this 21-kDa ACTH-induced protein as the tissue inhibitor of metalloproteinase-2 (TIMP-2). The induction of TIMP-2 by ACTH required transcription, was mimicked by 8-bromo cyclic 3'-5' adenosine monophosphate, but was not observed in response to angiotensin II, IGF-1, fibroblast growth factor-2, transforming growth factor-beta1, or cortisol treatments. ACTH stimulated TIMP-2 mRNA levels by a factor 4, whereas TIMP-1 mRNA levels were not affected and TIMP-3 mRNA remained undetectable. The biological activity of TIMP-2 varied accordingly, as we observed that the conditioned medium of ACTH-treated BAC cells was four times more potent at inhibiting gelatinolytic activity than was the conditioned medium of control cells. Because the proteolytic activity of both progelatinase-B and progelatinase-A secreted by BAC cells remained latent, whether in the presence or in the absence of ACTH, a paracrine rather than autocrine role is proposed for TIMP-2 in the adrenal cortex.

Mitochondrial thioredoxin reductase in bovine adrenal cortex its purification, properties, nucleotide/amino acid sequences, and identification of selenocysteine

Mitochondrial thioredoxin reductase was purified from bovine adrenal cortex. The enzyme is a first protein component in the mitochondrial thioredoxin-dependent peroxide reductase system. The purified reductase exhibited an apparent molecular mass of 56 kDa on SDS/PAGE, whereas the native protein was about 100 kDa, suggesting a homodimeric structure. It catalysed NADPH-dependent reduction of 5, 5'dithiobis(2-nitrobenzoic acid) and thioredoxins from various origins but not glutathione, oxidized dithiothreitol, DL-alpha-lipoic acid, or insulin. Amino acid and nucleotide sequence analyses revealed that it had a presequence composed of 21 amino acids which had features characteristic of a mitochondrial targeting signal. The amino acid sequence of the mature protein was similar to that of bovine cytosolic thioredoxin reductase (57%) and of human glutathione reductase (34%) and less similar to that of Escherichia coli (19%) or yeast (17%) enzymes. Human and bovine cytosolic thioredoxin reductase were recently identified to contain selenocysteine (Sec) as one of their amino acid constituents. We also identified Sec in the C-terminal region of mitochondrial (mt)-thioredoxin reductase by means of MS and amino acid sequence analyses of the C-terminal fragment. The four-amino acid motif, Gly-Cys-Sec-Gly, which is conserved among all Sec-containing thioredoxin reductases, probably functions as the third redox centre of the enzyme, as the mitochondrial reductase was inhibited by 1-chloro-2,4-dinitrobenzene, which was reported to modify Sec and Cys covalently. It is known that mammalian thioredoxin reductase is different from bacterial or yeast enzyme in, for example, their subunit molecular masses and domain structures. These two different types of enzymes with similar activity are suggested to have evolved convergently. Our data clearly show that mitochondria, which might have originated from symbiotic prokaryotes, contain thioredoxin reductase similar to the cytosolic enzyme and different from the bacterial one.

Development of functional zonation in the rat adrenal cortex

In an attempt to elucidate the mechanism(s) through which the functional adrenal cortex is established, we analyzed immunohistochemically the expression of various markers for the adrenocortical zones, i.e. the zona glomerulosa (zG), the zona fasciculata (zF), and the zona reticularis (zR), as well as markers for the medulla, and further examined the distribution and behavior of DNA-synthesizing cells in rat adrenal glands during development. The results showed that 1) separation of the cortex and medulla, and the development of functional zonation in the cortex began at around the time of birth, 2) at fetal stages when cortical zonation was not established, DNA-synthesizing cells were found scattered throughout the gland, where they proliferated without significant migration, and 3) after birth in the adrenal cortex with established cortical zonation, DNA-synthesizing cells were localized near the undifferentiated zone between zG and zF, and then they migrated centripetally. Cell death appeared to occur in the innermost portion of the cortex, where many resident macrophages are present. These findings illustrate basic processes underlying adrenal development and suggest that the undifferentiated region is apparently the stem cell zone of the adrenal cortex that maintains the cortical zonation.

Graves-Basedow disease goiter: a model of Bax-Bcl2 regulated apoptosis

This study demonstrates the involvement of a Bax-Bcl2-dependent apoptotic process in Graves-Basedow thyroid disease, a pathological condition known for its spontaneously oscillating evolution. A continuous series of 86 cases of surgically treated Graves' thyroid was evaluated for apoptotic cell content identified by histological criteria and confirmed by terminal desoxynucleotidyl transferase-mediated desoxyuridine triphosphate nick end-labeling (TUNEL). A significant correlation was found between tissue features of Graves' disease (epithelial hyperplasia, cellular hypertrophy, colloid content) and the amount of apoptotic cells. No correlation was found with lymphocytic infiltrates. Significantly, 11 cases (about 12% of the series) with high-level apoptosis displayed the typical features of active Graves' disease over all tissue sections. In contrast, cases with no detectable apoptosis exhibited regressive tissue features of Graves' disease. An intermediate group of cases was characterized by tissue heterogeneity with hyperactive foci, rich in apoptosis, alternating with regressive areas lacking apoptosis. In this group the participation of apoptosis to the remodeling of Graves' thyroid parenchyma, in a tight balance with cell proliferation, was best illustrated. Moreover, the thyroid follicle by accumulating apoptotic cells and bodies, allowed a tentative chronological ordering of apoptosis steps in correlation with Bax-Bcl2 tissue distribution and cellular pattern. Our observations suggest that the initiation of apoptosis corresponds to a loss of cellular cohesion, a drop in Bcl2 expression, and a delocalization of Bax from a putative Golgi storage location to a mitochondrial distribution.

Prilocaine induces apoptosis in osteoblastic cells

PURPOSE

To determine whether prilocaine, a local anesthetic, induces apoptosis in osteoblastic cells.

METHODS

After reaching subconfluence, human osteoblastic Saos-2 and MG63 cells and mouse osteoblastic MC3T3-E1 cells were exposed for 48 hr to varying concentrations of prilocaine up to 10 mM and the cytotoxicity of the cells was analyzed by phase-contrast microscopy and WST-1 assay. Saos-2 cells treated for 48 hr with 5 mM prilocaine were stained with Hoechst 33342 and nuclear fragmentation was examined under a fluorescence microscope. DNA was extracted from the cells treated with 5 mM prilocaine and DNA ladder formation (a hallmark of apoptosis) was analyzed by agarose gel electrophoresis.

RESULT

Prilocaine induced cell death in Saos-2 cells in a dose- and time-dependent manner up to the concentration of 10 mM. Marked nuclear condensation and fragmentation of chromatin were observed in the prilocaine-treated cells. DNA ladder formation also was induced by prilocaine treatment. Prilocaine-induced DNA ladder formation was dose-dependent with maximal effect at a concentration of 5 mM and was time-dependent from 12 to 48 hr. DNA ladder formation was also induced by prilocaine treatment in human osteoblastic MG63 cells and mouse osteoblastic MC3T3-E1 cells. Cycloheximide prevented prilocaine-induced apoptosis in Saos-2 cells in a dose-dependent fashion up to 20 microM as determined by WST-1 assay and DNA ladder formation in agarose gel electrophoresis.

CONCLUSION

Osteoblastic cells treated with prilocaine exhibit both morphological and biochemical features indicative of apoptosis. The apoptotic mechanisms involve transcriptional regulation of specific proteins or protein synthesis.

Animal models of CRH deficiency

Corticotropin-releasing hormone (CRH), the major regulator of hypothalamic-pituitary-adrenal (HPA) axis, was first isolated due to its ability to stimulate the release of adrenocorticotropic hormone from the anterior pituitary. Later, it was also found to have also a wide spectrum of actions within the central nervous system and the periphery. Studies with pharmacological administration of this peptide and/or antagonists and antibody neutralization techniques have yielded important information concerning the physiological relevance of CRH. The development of CRH knockout mice (CRH KO) has been an important tool for addressing the physiologic and pathologic roles of CRH. This review describes the phenotype of CRH-deficient mice, as well as the use of this model to study the roles of CRH on fetal development and postnatal life. The role of CRH in prenatal development and postnatal regulation of the HPA axis, in activation of the reproductive system during stress, and in modulation of the immune function will be discussed. The review concludes with a comparison of CRH KO mice with other models of CRH deficiency.

Development of adrenal zonation in fetal rats defined by expression of aldosterone synthase and 11beta-hydroxylase

The adult rat adrenal cortex is comprised of three concentric steroidogenic zones that are morphologically and functionally distinguishable: the zona glomerulosa, zona intermedia, and the zona fasciculata/reticularis. Expression of the zone-specific steroidogenic enzymes, cytochrome P450 aldosterone synthase (P450aldo), and P450 11beta hydroxylase (P45011beta), produced by the zona glomerulosa and zona fasciculata/reticularis, respectively, can be used to define the adrenal cortical cell phenotype of these two zones. In this study, immunohistochemistry and in situ hybridization were used to determine the ontogeny of expression of P450aldo and P45011beta to monitor the pattern of development of the rat adrenal cortex. RIA was used to measure adrenal content of aldosterone and corticosterone, the resulting products of the two enzymatic pathways. Double immunofluorescent staining for both enzymes at gestational day 16 (E16) showed P45011beta protein expressed in cells distributed throughout most of the adrenal intermixed with a separate, but smaller, population of cells expressing P450aldo protein. Whereas expression of P45011beta protein retained a similar pattern of distribution from E16 to adulthood (ignoring distribution of SA-1 positive, presumptive medullary cells), P450aldo protein changed its pattern of distribution by E19, becoming localized in a discontinuous ring of cells adjacent to the capsule. By postnatal day 1, P450aldo protein distribution was similar to that observed in adult glands; P450aldo-positive cells formed a continuous zone underlying the capsule. In situ hybridization showed that the pattern of P45011beta messenger RNA expression paralleled protein expression at all times, whereas P450aldo messenger RNA paralleled protein at E19 and after, but was undetectable before E19. However, adrenal aldosterone and corticosterone, as measured by RIA, were detected by E16, supporting the functional capacity of both phenotypes for all ages studied. These data suggest that the development of the adrenal zona glomerulosa occurs in two distinct phases; initial expression of the glomerulosa phenotype in scattered cells of the inner cortex before E17, followed by a change in distribution to the outer cortex between E17 and E19. It is hypothesized that this change in distribution occurs via cell differentiation, rather than cell migration, and that a possible regulator of these events is the fetal renin-angiotensin system.

The association of type II pneumocytes and endothelial permeability with the pulmonary custocyte system in experimental acute pancreatitis

BACKGROUND

Pancreatitis-associated pulmonary injury is still associated with substantial mortality, especially when seen as a part of the multiple organ dysfunction syndrome.

METHODS

The present study aimed at evaluating alterations in type II pneumocytes and the potential relationship with the development of pulmonary injury after acute haemorrhagic pancreatitis induced by an intraductal infusion of 5% sodium taurodeoxycholate in the rat.

RESULTS

The results demonstrated that definite alterations in type II pneumocytes were noted 12 and 24 h after induction of pancreatitis, characterized by an increase in the number of vocalized lamellae, the exposed area of type II pneumocytes to alveolar airspace, cellular separation and apoptosis without alterations in cellular membrane integrity. Dysfunction of the pulmonary endothelial barrier was evidenced by an increase in pulmonary albumin flux and the leakage index as well as the migration of lanthanum probes from capillaries to interstitial tissues. The levels of tumour necrosis factor (TNF) in bronchoalveolar lavage fluid significantly increased during the initial phase (3 and 6 h) after pancreatitis. The phagocytic activity of the pulmonary custocyte system increased 3 and 12 h after induction of pancreatitis.

CONCLUSION

Thus, pulmonary endothelial barrier dysfunction, an activated custocyte system, and initial release of TNF seems to be involved in the pathogenesis of pancreatitis-associated type II pneumocyte compromise.

Models to elucidate the regulation of adrenal cell death

Hypophysectomy-induced apoptosis in the rat adrenal gland is slow (not apparent until 12-24 h) and in-situ, 3'-end labeling (ISEL) of DNA strand breaks is restricted to a subpopulation of zona reticularis cells. In addition, it is completely blocked by ACTH. By contrast, apoptosis in the intact rat adrenal gland, cultured in the absence of trophic support, is extensive and rapid. Culture-triggered apoptosis (as determined by oligonucleosome formation) is attenuated by ACTH and is largely restricted to the zonae fasciculata and reticularis even at 3 h (as determined by ISEL and DAPI cytochemistry). Thus, this organ culture system may help elucidate factors that can acutely regulate adrenocortical cell survival. Quartered glands have a nearly 2-fold increase in oligonucleosome formation compared to intact glands at 3 h and are resistant to the antiapoptotic action of ACTH. In contrast, ACTH-induced corticosterone secretion is not attenuated. Angiotensin II (Ang II) enhances culture-triggered apoptosis, and its apoptotic action is attenuated by ACTH. These observations suggest that 1) acute hormonal modulation of apoptosis may require some level of gross adrenal structural integrity, and 2) ACTH and Ang II act in an antagonistic fashion to regulate adrenocortical apoptosis. The apoptotic effect of Ang II may be mediated via the type 2 receptor.

Tissue remodelling in the adrenal gland

Adaptation of the adrenal gland to the demands of the organism is regulated functionally and structurally. Three common hypotheses on zonation in the adrenal gland, the migrational, zonal, and transformation field theories, try independently to reconcile the findings on structure, proliferation, and cell death. The classical theories on zonation are revisited in the light of recent data on cell death and renewal. In accordance with data on cell death as immunoreactivity against FAS(CD 95), an apoptosis-inducing receptor, in situ end labelling of fragmented DNA, and ultrastructural analyses, programmed cell death (PCD) occurs throughout the whole organ. The angiotensin II receptor subtypes described in the adrenal allow an additional regulation of tissue homeostasis by proliferative and even by the antiproliferative effects of the angiotensin II type 2 receptor. Proto-oncogenes are involved in the regulation of cell cycle and PCD, and adrenocorticotropin asserts its tissue integrating and differentiating effects by regulating proto-oncogenes such as c-jun, c-fos, jun-B and c-myc. Polypeptides involved in proliferation and DNA repair, such as proliferating cell nuclear antigen and Ki-67, have been found within zones of expected cell senescence. The expression of the class II major histocompatibility complex on normal adrenocortical cells allows cell-to-cell communication with the immune system and may trigger the Fas/Fas-ligand system to permit tissue regression and decreasing activity in both systems. In summary, new data allow us to reappraise and to reconcile the classical theories. Apoptosis is a physiological process in the adrenal gland. There is a differential regulation of apoptosis in the different zones. An investigation of this process may elucidate the basic mechanisms of adrenal zonation.

Progesterone therapy for endometrial carcinoma reduces cell proliferation but does not alter apoptosis

BACKGROUND

Although the anticancer effects of progesterone therapy for patients with endometrial carcinoma are widely acknowledged, a detailed assessment of the resultant morphologic alterations in tumor tissue kinetics has hitherto been lacking.

METHODS

Biopsy and hysterectomy specimens of 14 endometrial carcinomas (endometrioid-type) before and during progesterone therapy were studied to clarify changes in apoptosis and cell proliferation and their relation to morphologic alterations. The extent of squamous differentiation within tumor lesions was also examined.

RESULTS

In the good-response group, tumor cells took on characteristics of normal endometrial gland cells in the secretory phase. A positive correlation between reduction in the mitotic index and the degree of morphologic alterations during hormone therapy was observed, but the frequency of apoptotic cells did not vary. In both the good-response and poor-response groups, development or enlargement of squamous areas was observed, in comparison with the initial biopsy specimens.

CONCLUSIONS

These results suggest that prolonged progesterone administration can suppress cell proliferation in endometrial carcinomas through tumor cell differentiation without altering apoptosis, resulting in a shift in tissue kinetics toward a relative predominance of cell deletion. In addition, increases in the occurrence of squamous areas within tumors do not always appear to be related to treatment efficacy.

Corticotropin releasing factor receptor 1-deficient mice display decreased anxiety, impaired stress response, and aberrant neuroendocrine development

Corticotropin releasing factor (CRF) is a major integrator of adaptive responses to stress. Two biochemically and pharmacologically distinct CRF receptor subtypes (CRFR1 and CRFR2) have been described. We have generated mice null for the CRFR1 gene to elucidate the specific developmental and physiological roles of CRF receptor mediated pathways. Behavioral analyses revealed that mice lacking CRFR1 displayed markedly reduced anxiety. Mutant mice also failed to exhibit the characteristic hormonal response to stress due to a disruption of the hypothalamic-pituitary-adrenal (HPA) axis. Homozygous mutant mice derived from crossing heterozygotes displayed low plasma corticosterone concentrations resulting from a marked agenesis of the zona fasciculata region of the adrenal gland. The offspring from homozygote crosses died within 48 hr after birth due to a pronounced lung dysplasia. The adrenal agenesis in mutant animals was attributed to insufficient adrenocorticotropic hormone (ACTH) production during the neonatal period and was rescued by ACTH replacement. These results suggest that CRFR1 plays an important role both in the development of a functional HPA axis and in mediating behavioral changes associated with anxiety.

Hormonal modulation of apoptosis in the rat adrenal gland in vitro is dependent on structural integrity

The intact rat adrenal gland in short-term (3-h) organ culture may be amenable for the identification of factors involved in regulating adrenal cell apoptosis under defined conditions. In this model, culturing in the absence of trophic support (basal; control) triggered apoptosis in the intact rat adrenal gland; oligonucleosome formation, a measure of apoptosis, was 56.4-fold greater than that of glands snap-frozen at the start of incubation. Angiotensin II (Ang II) (100 nM) enhanced apoptosis by 67% over control. By contrast, adrenocorticotropin (ACTH) (100 nM) attenuated basal apoptosis by 59% and antagonized the enhanced apoptosis induced by Ang II back to the control level. Quartering of the glands enhanced basal oligonucleosome formation 182.2% greater than that of intact glands. Interestingly, quartering of the glands abolished the influences of Ang II and ACTH on apoptotic DNA fragmentation, but did not alter ACTH-induced corticosterone secretion. These data suggest that some level of gross adrenal structural information or compartmentalization, sufficiently disrupted by quartering, is required for the hormonal modulation of adrenal cell survival.

The influence of prolonged dexamethasone treatment of pregnant rats on the perinatal development of the adrenal gland of their offspring

The effects of prolonged dexamethasone (Dx) administration to pregnant rats on the structure and function of the adrenal glands of fetal and neonatal offspring have been investigated by combined stereological and ultrastructural methods, as well as by metaphase index determination. Pregnant rats were injected subcutaneously with Dx (0.3 mg/kg body weight/day) during 5 days, starting from day 16 of gestation. The dams and their fetuses were killed 24 hr after the last injection. The neonatal offspring were killed in the same way on the 3rd and 14th day of life. Because in fetal and 3-day-old neonatal rats zona reticularis (ZR) was poorly defined and could not be clearly seen as a separate zone, zona fasciculata (ZF) and ZR were analyzed as one, inner zone (IZ). In 14-day-old rats ZF and ZR were analyzed separately. Proliferative activity of adrenocortical cells was estimated following the application of Vincristine sulphate. Dx treatment of pregnant rats induced a marked decrease of fetal adrenal gland volume and the volumes of zona glomerulosa + capsula (ZG + C) and IZ as the consequence of atrophic changes in the gland and reduction of the average volume and total number of adrenocortical cells. Similar morphometric changes were found in 3- and 14-day-old pups. However, in 3-day-old animals the number of cortical cells in the ZG was increased, whereas on the 14th postnatal day cortical cell number remained decreased only in the ZF. The multinuclear giant cells, numerous lymphocytes, and the resorption zones, present in the adrenal cortex of fetuses and 3-day-old pups of both experimental and control dams, were not seen in 14-day-old offspring. These results demonstrate that prolonged treatment of pregnant rats with Dx in the period when intensive differentiation of the fetal hypothalamo-hypophyseal system takes place inhibits proliferative activity of adrenocortical cells and evokes considerable atrophic changes in the adrenal glands of offspring from 20 days gestation to 14 days after birth. The histological appearance of the adrenal cortex and the ultrastructure of adrenocortical cells suggest that cortical cell function was inhibited.

Cell kinetic in epithelium and stroma of benign prostatic hyperplasia

The induction of benign prostatic hyperplasia (BPH) from normal prostate is obviously associated with a distinct increase in epithelial and stromal proliferation. We have shown previously that the further increase of BPH volume in aging men is not associated with a further increase in proliferation. We studied whether an imbalance between programmed cell death (apoptosis) and cell proliferation may explain continuing growth in aging men. In prostates of 17 men with BPH removed by open prostatectomy proliferating cells were localized immunohistochemically with the Ki-67 antibody. Apoptotic cells were detected with the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method. Proliferation and apoptotic index was calculated with a computer assisted image analysis system. Mean proliferation index +/- standard deviation in epithelium (0.142 +/- 0.097) and stroma (0.121 +/- 0.082) was nearly identical. Mean apoptotic index in epithelium (0.172 +/- 0.156) was negligibly higher than the corresponding proliferation index. In stroma, however, no apoptotic cells were detectable. Proliferation index and apoptotic index in epithelium and proliferation index in stroma showed no correlation to patient age or prostate volume. In the epithelium of BPH, obviously the cell kinetic is balanced. On the other hand, our results indicate stromal growth due to cell proliferation in the absence of cell death. This may explain the continuous increase of BPH volume in aging men.

Apoptosis down-regulates inflammation under the advancing epithelial wound edge: delayed patterns in diabetes and improvement with topical growth factors

BACKGROUND

Wound healing is involved in many aspects of care, ranging from anastomoses and skin incisions to foot ulcers and decubitus. Clinical healing failures are a major challenge to the physician and cause significant morbidity and mortality in select patient populations. As we are starting to understand more fully the mechanisms of impaired wound healing, the diabetic mouse (C57BL/KsJ-db/db) has been a good model for research. The diabetic wound exhibits significant delays in healing, previously identified as impaired cellular infiltration and granulation tissue formation. Apoptosis, or programmed cell death, is intimately involved in the regulation of inflammation and ultimately should play a role in the inflammatory phase of wound healing.

METHODS

To examine its role in wound healing, patterns of apoptosis in large, full-thickness cutaneous wounds were compared between groups of diabetic and nondiabetic mice.

RESULTS

Initially apoptosis was mainly limited to the wound edge and followed the advancing epithelial edge toward the center of the wound as healing progressed. Significant delays in the appearance of the apoptotic pattern were noted in the diabetic mice. Wounds in diabetic mice were then treated with topical application of growth factors. The delay in apoptotic pattern was reversed after treatment with the combination of insulin-like growth factor-II and platelet-derived growth factor, approaching levels in nondiabetic animals.

CONCLUSIONS

Apoptosis appears concurrently with reepithelialization of the wound and may signal the end of the inflammatory phase of healing at that site in the wound. One can speculate that a signal for apoptosis and down-regulation of inflammation in the wound is derived from the epithelium.

Expression of laminin and its possible role in adrenal cortex homeostasis

The adult mammalian adrenal cortex undergoes permanent regeneration. This process implies a cellular proliferation step restricted to the external zone of the tissue, and a subsequent centripetal cell migration during which phenotypic transition from glomerulosa into fasciculata and reticularis cells and elimination of senescent cells through apoptosis occur. As the molecular mechanisms implied in adrenocortical cell migration are still generally unknown, we addressed that question in the present study. Of several extracellular matrix proteins tested, laminin was the most potent chemotactic and haptotactic factor for bovine fasciculata adrenocortical cells. The maximal chemotactic effect (3-fold stimulation) was observed with 50-75 micrograms/ml laminin, whereas the haptotactic effect (3.5-fold stimulation) plateaued for laminin concentrations in the coating solution over 25 micrograms/ml. Using an anti-Engelbreth-Holm-Swarm laminin antibody, we could demonstrate that adrenocortical cells actively synthesize and secrete Engelbreth-Holm-Swarm-laminin, with the A chain produced in limiting quantities. ACTH treatment of adrenocortical cells specifically induced a 2.7- to 4.5-fold increase in A chain synthesis, resulting in a corresponding increase in the amount of secreted laminin. The distribution of laminin in the adrenal cortex tissue was then evaluated by standard immunohistochemistry. The protein appeared to be uniformly expressed in the three zones of the cortex. This observation does not favor the hypothesis that laminin acts as an attractant driving centripetal cell migration. Laminin, which is synthesized under the control of the systemic hormone ACTH, appears as a permissive factor that facilitates proper homeostasis of the adrenocortical tissue.

Proliferation in Adrenocortical Tumors: Correlation with Clinical Outcome and p53 Status

There appears to be a relationship between mitotic activity and malignant behavior in adrenocortical tumors, and carcinomas with a high mitotic index may have a poorer prognosis. This has been investigated further by quantifying and comparing the Ki-67 index using antibody MIB-1 in a series of 14 adrenocortical adenomas and 40 carcinomas. The levels have been correlated with survival and disease-free survival in carcinomas and with evidence of abnormal p53 expression as detected by immunohistochemistry. Nevertheless, many carcinomas have a low level of proliferation that may reflect varying abnormalities within the regulation of both cell division and apoptosis. Expression of bcl-2 protein, an inhibitor of apoptosis has therefore also been examined. The Ki-67 index in carcinomas was significantly higher than in adenomas, but below 4% there was overlap. There was no significant difference in survival between carcinomas with MIB-1 index <3% and those greater, but the lower group had significantly longer disease-free survival (p = 0.02). There was no significant difference between p53 immunopositive and p53 immunonegative carcinomas. No tumor showed immunopositivity for bcl-2 protein. It is concluded that MIB-1 index may contribute additional prognostic information in adrenocortical tumors. Inhibition of apoptosis by bcl-2 does not appear to play a role in tumor growth.