Environmental characteristics and disparities in adult asthma in north central Texas urban counties.

OBJECTIVES: Disparities in asthma prevalence present a persistent challenge to public health. The complex nature of the issue requires studies through a wide range of lenses. To date, little research has examined associations between asthma and multiple social and environmental factors simultaneously. This study aims to fill the gap with a focus on the impacts of multiple environmental characteristics and social determinants of health on asthma. STUDY DESIGN: This study uses secondary analysis with data from a variety of sources to analyze the effects of environmental and social factors on adult asthma occurrence in North Central Texas. METHOD: Hospital records and demographic and environmental data for four urban counties in North Central Texas (Collin, Dallas, Denton, and Tarrant) come from the Dallas/Fort Worth Hospital Council Foundation, the US census, the North Central Texas Council of Governments, and the Railroad Commission of Texas. The data were integrated using ArcGIS. A hotspot analysis was performed to inspect the spatial patterns of hospital visits for asthma exacerbations in 2014. The impacts of multiple environmental characteristics and social determinants of health were modeled using negative binomial regression. RESULTS: The results revealed spatial clusters of adult asthma prevalence and disparities by race, class, and education. The occurrence of asthma exacerbations was positively associated with exposure to traffic-related air pollution, energy-related drilling activities, and older housing stock and negatively linked to green space. CONCLUSIONS: Associations between built environmental characteristics and asthma prevalence have implications for urban planners, healthcare professionals, and policy makers. Empirical evidence for the role of social determinants of health supports continuing efforts in policies and practices to improve education and reduce socio-economic inequities.

Cannabis use is associated with patient and clinical factors in a population-based sample of colorectal cancer survivors.

PURPOSE: This study aimed to characterize patient and clinical factors associated with cannabis (marijuana) use among patients diagnosed with colorectal cancer (CRC). METHODS: We identified CRC patients, diagnosed from 2016 to 2018, using the Seattle-Puget Sound Surveillance, Epidemiology, and End Results (SEER) cancer registry. CRC patients were recruited via mail and telephone, and participants completed a questionnaire eliciting information on medical history, demographics, and lifestyle factors, including cannabis use. Cancer stage was obtained from SEER registry data. RESULTS: Of 1,433 survey respondents, 339 (24%) were current cannabis users. Current cannabis use was associated with younger age at diagnosis, lower BMI, and a higher prevalence of cigarette smoking and alcohol consumption (p-value < 0.05). Cannabis use was also associated with lower quality of life scores (FACT-C) and advanced-stage cancer (p-value < 0.05). CONCLUSION: Cannabis use among CRC patients was common. Patients with more advanced disease were more likely to report cannabis use. Use also varied by some personal factors, consistent with patterns in the general population. Given the high prevalence of cannabis use among CRC patients, research is needed to determine the benefits and harms of cannabis use for symptom management in cancer patients.

Senescence-associated tissue microenvironment promotes colon cancer formation through the secretory factor GDF15.

The risk of colorectal cancer (CRC) varies between people, and the cellular mechanisms mediating the differences in risk are largely unknown. Senescence has been implicated as a causative cellular mechanism for many diseases, including cancer, and may affect the risk for CRC. Senescent fibroblasts that accumulate in tissues secondary to aging and oxidative stress have been shown to promote cancer formation via a senescence-associated secretory phenotype (SASP). In this study, we assessed the role of senescence and the SASP in CRC formation. Using primary human colon tissue, we found an accumulation of senescent fibroblasts in normal tissues from individuals with advanced adenomas or carcinomas in comparison with individuals with no polyps or CRC. In in vitro and ex vivo model systems, we induced senescence using oxidative stress in colon fibroblasts and demonstrated that the senescent fibroblasts secrete GDF15 as an essential SASP factor that promotes cell proliferation, migration, and invasion in colon adenoma and CRC cell lines as well as primary colon organoids via the MAPK and PI3K signaling pathways. In addition, we observed increased mRNA expression of GDF15 in primary normal colon tissue from people at increased risk for CRC in comparison with average risk individuals. These findings implicate the importance of a senescence-associated tissue microenvironment and the secretory factor GDF15 in promoting CRC formation.

Prediction of overall survival in stage II and III colon cancer beyond TNM system: a retrospective, pooled biomarker study.

Background: TNM staging alone does not accurately predict outcome in colon cancer (CC) patients who may be eligible for adjuvant chemotherapy. It is unknown to what extent the molecular markers microsatellite instability (MSI) and mutations in BRAF or KRAS improve prognostic estimation in multivariable models that include detailed clinicopathological annotation. Patients and methods: After imputation of missing at random data, a subset of patients accrued in phase 3 trials with adjuvant chemotherapy (n = 3016)-N0147 (NCT00079274) and PETACC3 (NCT00026273)-was aggregated to construct multivariable Cox models for 5-year overall survival that were subsequently validated internally in the remaining clinical trial samples (n = 1499), and also externally in different population cohorts of chemotherapy-treated (n = 949) or -untreated (n = 1080) CC patients, and an additional series without treatment annotation (n = 782). Results: TNM staging, MSI and BRAFV600E mutation status remained independent prognostic factors in multivariable models across clinical trials cohorts and observational studies. Concordance indices increased from 0.61-0.68 in the TNM alone model to 0.63-0.71 in models with added molecular markers, 0.65-0.73 with clinicopathological features and 0.66-0.74 with all covariates. In validation cohorts with complete annotation, the integrated time-dependent AUC rose from 0.64 for the TNM alone model to 0.67 for models that included clinicopathological features, with or without molecular markers. In patient cohorts that received adjuvant chemotherapy, the relative proportion of variance explained (R2) by TNM, clinicopathological features and molecular markers was on an average 65%, 25% and 10%, respectively. Conclusions: Incorporation of MSI, BRAFV600E and KRAS mutation status to overall survival models with TNM staging improves the ability to precisely prognosticate in stage II and III CC patients, but only modestly increases prediction accuracy in multivariable models that include clinicopathological features, particularly in chemotherapy-treated patients.

Characterisation of familial colorectal cancer Type X, Lynch syndrome, and non-familial colorectal cancer.

BACKGROUND: Familial Colorectal Cancer Type X (FCCTX) is defined as individuals with colorectal cancer (CRC) who families meet Amsterdam Criteria-1 (AC1), but whose tumours are DNA-mismatch-repair-proficient, unlike Lynch syndrome (LS). FCCTX does not have an increased risk of extra-colonic cancers. This analysis compares epidemiologic and clinicopathologic features among FCCTX, LS, and 'non-familial' (non-AC1) CRC cases. METHODS: From the Colon Cancer Family Registry, FCCTX (n=173), LS (n=303), and non-AC1 (n=9603) CRC cases were identified. Questionnaire-based epidemiologic information and CRC pathologic features were compared across case groups using polytomous logistic regression. RESULTS: Compared with LS, FCCTX cases were less likely to be current (vs never) smokers; have a proximal subsite (vs rectal) tumour; or have mucinous histology, poor differentiation, or tumour-infiltrating lymphocytes. There were no observed differences in co-morbidities or medication usage. CONCLUSIONS: FCCTX were less likely to be current tobacco users; other exposures were similar between these groups. Histopathologic differences highly suggestive of LS CRCs do not appear to be shared by FCCTX.

KRAS-mutation status in relation to colorectal cancer survival: the joint impact of correlated tumour markers.

BACKGROUND: Mutations in the Kirsten Ras (KRAS) oncogene are common in colorectal cancer (CRC). The role of KRAS-mutation status as a prognostic factor, however, is unclear. We evaluated the relationship between KRAS-mutation status and CRC survival, considering heterogeneity in this association by tumour and patient characteristics. METHODS: The population-based study included individuals diagnosed with CRC between 1998-2007 in Western Washington State. Tumour specimens were tested for KRAS exon 2 mutations, the BRAF p.V600E mutation, and microsatellite instability (MSI). We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association between KRAS-mutation status and disease-specific and overall survival. Stratified analyses were conducted by age, sex, tumour site, stage, and MSI. We conducted additional analyses combining KRAS-mutation, BRAF-mutation, and MSI status. RESULTS: Among 1989 cases, 31% had KRAS-mutated CRC. Kirsten Ras (KRAS)-mutated CRC was associated with poorer disease-specific survival (HR=1.37, 95% CI: 1.13-1.66). This association was not evident in cases who presented with distant-stage CRC. Cases with KRAS-wild-type/BRAF-wild-type/MSI-high CRC had the most favourable prognosis; those with CRC exhibiting a KRAS- or BRAF-mutation and no MSI had the poorest prognosis. Patterns were similar for overall survival. CONCLUSION: Kirsten Ras (KRAS)-mutated CRC was associated with statistically significantly poorer survival after diagnosis than KRAS-wild-type CRC.

Reproductive factors and histologic subtype in relation to mortality after a breast cancer diagnosis.

Evidence suggests that certain reproductive factors are more strongly associated with the incidence of lobular than of ductal breast cancer. The mechanisms influencing breast cancer incidence histology may also affect survival. Women with invasive breast cancer (N = 22,302) diagnosed during 1986-2005 were enrolled in a series of population-based studies in three US states. Participants completed telephone interviews regarding reproductive exposures and other breast cancer risk factors. Histologic subtype was obtained from state cancer registries. Vital status and cause of death were determined through December 2006 using the National Death Index. Women were followed for 9.8 years on average with 3,050 breast cancer deaths documented. Adjusted hazard rate ratios (HR) and 95% confidence intervals (95% CI) were calculated using Cox proportional hazards regression models for breast cancer-specific and all-cause mortality. Parity was inversely associated with breast cancer-specific mortality (P (Trend) = 0.002). Associations were similar though attenuated for all-cause mortality. In women diagnosed with ductal breast cancer, a 15% reduction in breast cancer-specific mortality was observed in women with five or more children when compared to those with no children (HR = 0.85, 95% CI: 0.73-1.00). A similar inverse though non-significant association was observed in women with lobular subtype (HR = 0.70, 95% CI: 0.43-1.14). The trend did not extend to mixed ductal-lobular breast cancer. Age at first birth had no consistent relationship with breast cancer-specific or all-cause mortality. We found increasing parity reduced mortality in ductal and lobular breast cancer. The number of full-term births, rather than age at first birth, has an effect on both breast cancer-specific and overall mortality.

Body mass index in early adulthood and colorectal cancer risk for carriers and non-carriers of germline mutations in DNA mismatch repair genes.

BACKGROUND: Carriers of germline mutations in DNA mismatch repair (MMR) genes have a high risk of colorectal cancer (CRC), but the modifiers of this risk are not well established. We estimated an association between body mass index (BMI) in early adulthood and subsequent risk of CRC for carriers and, as a comparison, estimated the association for non-carriers. METHODS: A weighted Cox regression was used to analyse height and weight at 20 years reported by 1324 carriers of MMR gene mutations (500 MLH1, 648 MSH2, 117 MSH6 and 59 PMS2) and 1219 non-carriers from the Colon Cancer Family Registry. RESULTS: During 122,304 person-years of observation, we observed diagnoses of CRC for 659 carriers (50%) and 36 non-carriers (3%). For carriers, the risk of CRC increased by 30% for each 5 kg m(-2) increment in BMI in early adulthood (hazard ratio, HR: 1.30; 95% confidence interval, CI: 1.08-1.58; P=0.01), and increased by 64% for non-carriers (HR: 1.64; 95% CI: 1.02-2.64; P=0.04) after adjusting for sex, country, cigarette smoking and alcohol drinking (and the MMR gene that was mutated in carriers). The difference in HRs for carriers and non-carriers was not statistically significant (P=0.50). For MLH1 and PMS2 (MutLα heterodimer) mutation carriers combined, the corresponding increase was 36% (HR: 1.36; 95% CI: 1.05-1.76; P=0.02). For MSH2 and MSH6 (MutSα heterodimer) mutation carriers combined, the HR was 1.26 (95% CI: 0.96-1.65; P=0.09). There was no significant difference between the HRs for MutLα and MutSα heterodimer carriers (P=0.56). CONCLUSION: Body mass index in early adulthood is positively associated with risk of CRC for MMR gene mutation carriers and non-carriers.

Pre-diagnostic NSAID use but not hormone therapy is associated with improved colorectal cancer survival in women.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) and hormone therapy (HT) independently decrease the risk of colorectal cancer. However, their role in altering survival after a colorectal cancer diagnosis is not well established. METHODS: We examined the association between the use of these common medications before diagnosis and colorectal cancer survival among women in western Washington State diagnosed with incident colorectal cancer from 1997 to 2002. Cases were ascertained using the Surveillance, Epidemiology and End Results cancer registry; mortality follow-up was completed through linkages to the National Death Index. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: We observed no overall association between colorectal cancer survival and pre-diagnostic NSAID use. However, when stratified by tumour sub-site, NSAID use was associated with a reduced risk of colorectal cancer mortality for women diagnosed with proximal (HR=0.55; 95% CI: 0.32-0.92), but not distal or rectal (HR=1.32; 95% CI: 0.83-2.10) tumours. The usage of HT was not associated with colorectal cancer survival overall or by tumour sub-site. CONCLUSION: Usage of NSAIDs before diagnosis may be associated with improved colorectal cancer survival among women diagnosed with proximal tumours. The usage of HT does not appear to have a function in altering colorectal cancer mortality.

Bisphosphonates for osteoporosis treatment are associated with reduced breast cancer risk.

BACKGROUND: Bisphosphanates are used primarily for the prevention and treatment of osteoporosis, and are also indicated for osseous complications of malignancy. In addition to their bone resorption properties, the most commonly used nitrogen-containing bisphosphonate compounds also inhibit protein prenylation, and thus may exert anti-tumour properties. METHODS: To evaluate whether the use of these drugs may be associated with cancer, specifically breast cancer, we conducted a population-based case-control study in Wisconsin from 2003 to 2006. Participants included 2936 incident invasive breast cancer cases and 2975 population controls aged < 70 years. Bisphosphonate use and potential confounders were assessed by interview. RESULTS: Using multivariable logistic regression, the odds ratio for breast cancer in current bisphosphonate users compared with non-users was 0.67 (95% confidence interval 0.51-0.89). Increasing duration of use was associated with a greater reduction in risk (P-trend=0.01). Risk reduction was observed in women who were not obese (P-interaction=0.005). CONCLUSION: These results are suggestive of an additional benefit of the common use of bisphosphonates, in this instance, the reduction in breast cancer risk.

Inverse association of NSAID use and ovarian cancer in relation to oral contraceptive use and parity.

We examined the association between non-steroidal anti-inflammatory drug (NSAID) use and ovarian cancer by potential effect modifiers, parity and oral contraceptive use, in a population-based case-control study conducted in Wisconsin and Massachusetts. Women reported prior use of NSAIDs and information on risk factors in a telephone interview. A total of 487 invasive ovarian cancer cases and 2653 control women aged 20-74 years were included in the analysis. After adjustment for age, state of residence and other covariates, ever use of NSAIDs was inversely associated with ovarian cancer in never users of oral contraceptives (odds ratio (OR)=0.58, 95% confidence interval (CI) 0.42-0.80) but not for ever users (OR=0.98, 95% CI 0.71-1.35) (P-interaction=0.03). A reduced risk with NSAID use was also noted in nulliparous women (OR=0.47, 95% CI 0.27-0.82) but not among parous women (OR=0.81, 95% CI 0.64-1.04) (P-interaction=0.05). These results suggest that use of NSAIDs were beneficial to women at greatest risk for ovarian cancer.

Urinary cadmium levels and tobacco smoke exposure in women age 20-69 years in the United States.

Cadmium is a toxic, bioaccumulated heavy metal with a half-life of one to four decades in humans (CDC, 2005). Primary exposure sources include food and tobacco smoke. In our population-based study, a risk-factor interview was conducted as part of a breast cancer study for 251 randomly selected women living in Wisconsin (USA), aged 20-69 yr, and spot-urine specimens were also obtained. Urine collection kits were carefully designed to minimize trace element contamination during specimen collection and handling in each participant's home. Urine cadmium concentrations were quantified using inductively coupled plasma-mass spectrometry, and creatinine levels and specific gravity were also determined. Statistically significant increasing creatinine-adjusted urinary cadmium mean levels relative to smoking status (never, former, and current respectively) were observed. A difference in mean cadmium levels for nonsmokers who reported environmental tobacco smoke exposure during childhood or the recent past (approximately 2 yr prior to the interview) for exposure at home, at work, or in social settings compared to those who reported no exposure was not found.

Whole genome amplification of buccal cytobrush DNA collected for molecular epidemiology studies.

When cytobrush buccal cell samples have been collected as a genomic DNA (gDNA) source for an epidemiological study, whole genome amplification (WGA) can be critical to maintain sufficient DNA for genotyping. We evaluated REPLI-g WGA using gDNA from two paired cytobrushes (cytobush 'A' kept in a cell lysis buffer, and 'B' dried and kept at room temperature for 3 days, and frozen until DNA extraction) in a pilot study (n=21), and from 144 samples collected by mail in a breast cancer study. WGA success was assessed as the per cent completion/concordance of STR/SNP genotypes. Locus amplification bias was assessed using quantitative PCR of 23 human loci. The pilot study showed > 98% completion but low genotype concordance between cytobrush wgaDNA and paired blood gDNA (82% and 84% for cytobrushes A and B, respectively). Substantial amplification bias was observed with significantly lower human gDNA amplification from cytobrush B than A. Using cytobrush gDNA samples from the breast cancer study (n =20), an independent laboratory demonstrated that increasing template gDNA to the REPLI-g reaction improved genotype performance for 49 SNPs; however, average completion and concordance remained below 90%. To reduce genotype misclassification when cytobrush wgaDNA is used, inclusion of paired gDNA/wgaDNA and/or duplicate wgaDNA samples is critical to monitor data quality.

Obesity, diabetes, and other factors in relation to survival after endometrial cancer diagnosis.

Endogenous and exogenous sources of estrogen and characteristics altering these hormone levels have been related to endometrial cancer risk; however, their relationship to survival following diagnosis is less clear. In a population-based study, we examined whether mortality after endometrial cancer diagnosis was affected by prediagnosis obesity, diabetes, smoking, oral contraceptive use, parity, or postmenopausal hormone (PMH) use. Eligible women, aged 40-79 years, diagnosed from 1991-1994 with incident invasive endometrial cancer and identified through the Wisconsin statewide mandatory cancer registry were invited to participate. Of 745 eligible cases, 166 women were deceased after 9.3 years of follow-up, with 43 attributable to endometrial cancer, based upon vital records linkage. Hazard rate ratios (HRR) and 95% confidence intervals were adjusted for age at diagnosis, menopausal status, stage of disease, and other exposures of interest. Obese women (body mass index [BMI] >or=30 kg/m(2)) prior to endometrial cancer diagnosis had an increased risk of both all-cause (HRR=1.6, 95% CI 1.0-2.5) and endometrial cancer (HRR=2.0, 95% CI 0.8-5.1) mortality, compared with nonoverweight women (BMI<25 kg/m(2)). Endometrial cancer cases with diabetes also had an increased risk of all-cause mortality compared with nondiabetic women (HRR=1.7, 95% CI 1.1-2.5), although there was no association with endometrial cancer mortality. There were no associations between PMH use, oral contraceptive use, parity, or smoking and mortality from any cause. The results suggest that history of obesity and diabetes may increase risk of mortality after endometrial cancer diagnosis; modification of these characteristics may improve survival after endometrial cancer diagnosis.

Cholecystectomy and endometrial cancer: a marker of long-term elevated estrogen exposure?

Excess hormones, both endogenous and exogenous, are implicated in the etiology of endometrial cancer. We considered whether having had gallstones or a cholecystectomy (surgery to remove the gallbladder), which are more common in women who are obese and who use exogenous hormones, might be a marker for high lifetime levels of estrogen. We conducted a population-based study of endometrial cancer cases and community controls in women aged 40-79 years. Participants completed an interviewer-administered questionnaire that elicited exposures prior to diagnosis or reference date, including history of gallstones and cholecystectomy, as well as reproductive history, lifetime body mass, smoking, postmenopausal hormone (PMH) use, and other risk factors. Compared to controls, cholecystectomy was associated with a 50% increased risk of developing endometrial cancer (odds ratio = 1.5 [1.1-2.0]). The relationship appeared to depend upon PMH user status; the association was observed only among never hormone users. Body mass index did not appear to modify this relationship. Having a diagnosis of gallstones was also associated with endometrial cancer, although to a lesser magnitude. Although other etiologic factors may play a role in the relation between cholecystectomy and endometrial cancer, the current analysis suggests that this association is attributable, at least in part, to the sharing of hormonal risk factors.

Weight change and risk of endometrial cancer.

BACKGROUND: Obesity is an established risk factor for endometrial cancer. Less well understood is the role of weight gain and weight change in determining risk. METHODS: We analysed data from a population-based case-control study to evaluate the associations of body mass index (BMI), weight gain, and weight cycling with risk of endometrial cancer. Cases (n=740) under age 80 with a new diagnosis of endometrial cancer were identified from Wisconsin's cancer registry. Controls (n=2342) were randomly selected from driver's license lists and Medicare beneficiary files. Body size at three time points and other risk factor information were ascertained by interview in 1992-95. RESULTS: Endometrial cases were more likely than controls to be nulliparous, have early ages at menarche and late ages at menopause, be diabetic, smoke cigarettes, and use post-menopausal hormones. After adjustment for these factors, increasing BMI was associated with increased risk (P-trend<0.001); women in the top quartile of BMI (>29 kg/m2) had a 3-fold greater risk of endometrial cancer [95% confidence interval (95% CI) 2.4-4.2] compared with women in the lowest quartile (<23 kg/-m2). For each 5 kg weight gain, the odds ratio (OR) for endometrial cancer risk equalled 1.2 (95% CI 1.2-1.3). History of weight cycling modestly increased risk after adjustment for BMI and other factors (OR=1.3; 95% CI 1.0-1.6). In addition, women who reported sustained weight loss had a reduced risk of endometrial cancer (OR=0.7; 95% CI 0.6-0.9). CONCLUSIONS: These results suggest that weight gain and lack of weight stability are associated with risk of endometrial cancer.

Incomplete screening flexible sigmoidoscopy associated with female sex, age, and increased risk of colorectal cancer.

BACKGROUND: Several previous studies have found that females and older individuals are at greater risk of having incomplete flexible sigmoidoscopy. However, no prior study has reported the subsequent risk of colorectal cancer (CRC) following incomplete sigmoidoscopy. METHODS: Using data from 55 791 individuals screened as part of the Colon Cancer Prevention (CoCaP) programme of Kaiser Permanente of Northern California, we evaluated the likelihood of having an inadequate (<40 cm) examination by age and sex, and estimated the risk of distal CRC according to depth of sigmoidoscope insertion at the baseline screening examination. Multivariate estimation of risks was performed using Poisson regression. RESULTS: Older individuals were at a much greater risk of having an inadequate examination (relative risk (RR) for age 80+ years compared with 50-59 years 2.6 (95% confidence interval (CI) 2.3-3.0)), as were females (RR 2.3 (95% CI 2.2-2.5)); these associations were attenuated but remained strong if Poisson models were further adjusted for examination limitations (pain, stool, and angulation). There was an approximate threefold increase in the risk of distal CRC if the baseline sigmoidoscopy did not reach a depth of at least 40 cm; a smaller increase in risk was observed for examinations that reached 40-59 cm. CONCLUSIONS: Older individuals and women are at an increased risk of having inadequate sigmoidoscopy. Because inadequate sigmoidoscopy results in an increased risk of subsequent CRC, physicians should consider steps to maximise the depth of insertion of the sigmoidoscope or, failing this, should consider an alternative screening test.

Multifaceted roles of TNF-alpha in myoblast destruction: a multitude of signal transduction pathways.

In catabolic conditions, such as cancer cachexia, a balance favouring a cytokine environment culminates in muscle destruction. Utilising an in vitro model to mimic muscle wasting, we elucidate here the multifaceted roles that one such cytokine, TNF-alpha, invokes in the degeneration process. Treatment of C2 skeletal myoblasts with TNF-alpha not only suppresses morphological and biochemical differentiation, but following an initial wave of proliferation, and of survival (24 h), induces apoptosis. Investigating the mechanisms underlying these diverse actions of TNF-alpha, we demonstrate that cell replication is dependent on rapid and sustained activation of MAP kinase. Map kinase is not, however, central to the death process, which is associated with a progressive rise in caspase-8 activity, and is accompanied by sustained activation of JNK1 and transient activation of JNK2. Caspase inhibition caused a dose responsive reduction in cell death, while inhibition of the JNKs caused a significant increase in apoptosis. We further report that PI3 kinase is not involved in conferring early protection against TNF-alpha-induced death. By contrast, inhibition of NF-kappaB in the presence of TNF-alpha culminates in increased cell cycle progression, decreased gadd45beta expression and significant and precociously increased cell death, when compared with TNF-alpha alone. Our results begin to characterise the mechanisms underlying the acute mitogenic and anti-apoptotic roles of TNF-alpha, which appear to be defined by a balance between MAP kinase, Jun kinase (JNK), NF-kappaB and gadd45beta. They establish that inhibition of any one of these molecules, as may occur following caspase activation, could eliminate vital stem cells required for skeletal muscle regeneration during chronic catabolic conditions.

Prolactin acts as a potent survival factor against C2-ceramide-induced apoptosis in human granulosa cells.

BACKGROUND: The role of prolactin in the regulation of ovarian folliculogenesis and corpus luteal function and in particular its relationship to atresia in these structures is as yet unclear. We established a model of apoptosis in which to examine the actions of prolactin. METHOD: Granulosa cells collected from IVF-flush were cultured at 0.1-0.3 x 10(6) cells/well in growth media for 48 h, placed into serum-free media for 24 h prior to dosing for 24 h. Dose responses to C2-ceramide and prolactin were performed. Cells were then treated with an apoptotic dose of C2-ceramide alone, prolactin (100 ng/ml) alone or a combination of the two. Cell death was assessed by Trypan Blue cell counting and MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; Thiazolyl Blue] assay and apoptosis confirmed by morphological assessment and flow cytometry. RESULTS: C2-ceramide (0-40 micro mol/l) induced a dose-dependent increase in cell death (63.8% increase at 40 micro mol/l) and, morphologically, cells exhibited classical features of apoptosis. Prolactin alone had no effect on metabolic activity or total cell number. On co- incubation, prolactin alone had no effect on cell death, whereas C2-ceramide induced an approximately 62.6% increase in apoptosis, which was inhibited in the presence of prolactin. CONCLUSIONS: Prolactin may contribute significantly to early corpus luteum formation and survival by acting as a potent antiapoptotic factor for human granulosa cells.