Effect of substituents at the C3´, C3´N, C10 and C2-meta-benzoate positions of taxane derivatives on their activity against resistant cancer cells.

We tested the effect of substituents at the (1) C3´, C3´N, (2) C10, and (3) C2-meta-benzoate positions of taxane derivatives on their activity against sensitive versus counterpart paclitaxel-resistant breast (MCF-7) and ovarian (SK-OV-3) cancer cells. We found that (1) non-aromatic groups at both C3´ and C3´N positions, when compared with phenyl groups at the same positions of a taxane derivative, significantly reduced the resistance of ABCB1 expressing MCF-7/PacR and SK-OV-3/PacR cancer cells. This is, at least in the case of the SB-T-1216 series, accompanied by an ineffective decrease of intracellular levels in MCF-7/PacR cells. The low binding affinity of SB-T-1216 in the ABCB1 binding cavity can elucidate these effects. (2) Cyclopropanecarbonyl group at the C10 position, when compared with the H atom, seems to increase the potency and capability of the derivative in overcoming paclitaxel resistance in both models. (3) Derivatives with fluorine and methyl substituents at the C2-meta-benzoate position were variously potent against sensitive and resistant cancer cells. All C2 derivatives were less capable of overcoming acquired resistance to paclitaxel in vitro than non-substituted analogs. Notably, fluorine derivatives SB-T-121205 and 121,206 were more potent against sensitive and resistant SK-OV-3 cells, and derivatives SB-T-121405 and 121,406 were more potent against sensitive and resistant MCF-7 cells. (4) The various structure-activity relationships of SB-T derivatives observed in two cell line models known to express ABCB1 favor their complex interaction not based solely on ABCB1.

Current State and Future Directions of EGFR-Directed Therapy in Head and Neck Cancer.

OPINION STATEMENT: Epidermal growth factor receptor (EGFR) is commonly overexpressed in many head and neck squamous cell carcinomas (HNSCC). With the success of EGFR inhibition in other cancer types, there was optimism for efficacy in HNSCC. Unfortunately, the clinical outcomes of EGFR-directed therapy have not provided overwhelming benefit. In the curative-intent setting, cisplatin has proven superior over cetuximab, an EGFR monoclonal antibody, in multiple large trials, and cisplatin should continue to be the treatment of choice when administered with definitive or adjuvant radiation. For cisplatin-ineligible patients, we prefer carboplatin-based treatment over cetuximab. We reserve cetuximab for a small group of patients who are eligible for radiation and systemic treatment but have contraindications to any platinum therapy. The role of EGFR inhibitors in the recurrent/metastatic setting is more robust. Although supplanted by immunotherapy as front-line treatment, cetuximab remains a meaningful second-line option for patients who have progressed on immune checkpoint inhibitors. Overall, EGFR-directed therapies have been of modest value in the treatment of both locally advanced and metastatic HNSCC. The future of EGFR-directed therapies will likely develop from exploring combination therapies, especially with immunotherapy. Early evidence suggests synergistic effects allowing for a more robust immune response, which holds promise for novel regimens in the treatment of HNSCC.

Effect of Aspirin on Cardiovascular Events and Bleeding in the Healthy Elderly.

BACKGROUND: Aspirin is a well-established therapy for the secondary prevention of cardiovascular events. However, its role in the primary prevention of cardiovascular disease is unclear, especially in older persons, who have an increased risk. METHODS: From 2010 through 2014, we enrolled community-dwelling men and women in Australia and the United States who were 70 years of age or older (or ≥65 years of age among blacks and Hispanics in the United States) and did not have cardiovascular disease, dementia, or disability. Participants were randomly assigned to receive 100 mg of enteric-coated aspirin or placebo. The primary end point was a composite of death, dementia, or persistent physical disability; results for this end point are reported in another article in the Journal. Secondary end points included major hemorrhage and cardiovascular disease (defined as fatal coronary heart disease, nonfatal myocardial infarction, fatal or nonfatal stroke, or hospitalization for heart failure). RESULTS: Of the 19,114 persons who were enrolled in the trial, 9525 were assigned to receive aspirin and 9589 to receive placebo. After a median of 4.7 years of follow-up, the rate of cardiovascular disease was 10.7 events per 1000 person-years in the aspirin group and 11.3 events per 1000 person-years in the placebo group (hazard ratio, 0.95; 95% confidence interval [CI], 0.83 to 1.08). The rate of major hemorrhage was 8.6 events per 1000 person-years and 6.2 events per 1000 person-years, respectively (hazard ratio, 1.38; 95% CI, 1.18 to 1.62; P<0.001). CONCLUSIONS: The use of low-dose aspirin as a primary prevention strategy in older adults resulted in a significantly higher risk of major hemorrhage and did not result in a significantly lower risk of cardiovascular disease than placebo. (Funded by the National Institute on Aging and others; ASPREE ClinicalTrials.gov number, NCT01038583 .).

The Role of TRIP6, ABCC3 and CPS1 Expression in Resistance of Ovarian Cancer to Taxanes.

The main problem precluding successful therapy with conventional taxanes is de novo or acquired resistance to taxanes. Therefore, novel experimental taxane derivatives (Stony Brook taxanes; SB-Ts) are synthesized and tested as potential drugs against resistant solid tumors. Recently, we reported alterations in ABCC3, CPS1, and TRIP6 gene expression in a breast cancer cell line resistant to paclitaxel. The present study aimed to investigate gene expression changes of these three candidate molecules in the highly resistant ovarian carcinoma cells in vitro and corresponding in vivo models treated with paclitaxel and new experimental Stony Brook taxanes of the third generation (SB-T-121605 and SB-T-121606). We also addressed their prognostic meaning in ovarian carcinoma patients treated with taxanes. We estimated and observed changes in mRNA and protein profiles of ABCC3, CPS1, and TRIP6 in resistant and sensitive ovarian cancer cells and after the treatment of resistant ovarian cancer models with paclitaxel and Stony Brook taxanes in vitro and in vivo. Combining Stony Brook taxanes with paclitaxel caused downregulation of CPS1 in the paclitaxel-resistant mouse xenograft tumor model in vivo. Moreover, CPS1 overexpression seems to play a role of a prognostic biomarker of epithelial ovarian carcinoma patients' poor survival. ABCC3 was overexpressed in EOC tumors, but after the treatment with taxanes, its up-regulation disappeared. Based on our results, we can suggest ABCC3 and CPS1 for further investigations as potential therapeutic targets in human cancers.

Optimising Secondary Prevention and Cardiac Rehabilitation for Atherosclerotic Cardiovascular Disease During the COVID-19 Pandemic: A Position Statement From the Cardiac Society of Australia and New Zealand (CSANZ).

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has introduced a major disruption to the delivery of routine health care across the world. This provides challenges for the use of secondary prevention measures in patients with established atherosclerotic cardiovascular disease (CVD). The aim of this Position Statement is to review the implications for effective delivery of secondary prevention strategies during the COVID-19 pandemic. CHALLENGES: The COVID-19 pandemic has introduced limitations for many patients to access standard health services such as visits to health care professionals, medications, imaging and blood tests as well as attendance at cardiac rehabilitation. In addition, the pandemic is having an impact on lifestyle habits and mental health. Taken together, this has the potential to adversely impact the ability of practitioners and patients to adhere to treatment guidelines for the prevention of recurrent cardiovascular events. RECOMMENDATIONS: Every effort should be made to deliver safe, ongoing access to health care professionals and the use of evidenced based therapies in individuals with CVD. An increase in use of a range of electronic health platforms has the potential to transform secondary prevention. Integrating research programs that evaluate the utility of these approaches may provide important insights into how to develop more optimal approaches to secondary prevention beyond the pandemic.

Differentially Expressed Mitochondrial Proteins in Human MCF7 Breast Cancer Cells Resistant to Paclitaxel.

Identification of novel proteins with changed expression in resistant cancer cells could be helpful in elucidation mechanisms involved in the development of acquired resistance to paclitaxel. In this study, we carried out a 2D-PAGE using the mitochondrial-enriched fraction from paclitaxel-resistant MCF7/PacR cells compared to original paclitaxel-sensitive MCF7 breast cancer cells. Differentially expressed proteins were identified employing mass spectrometry. We found that lysosomal cathepsin D and mitochondrial abhydrolase-domain containing protein 11 (ABHD11) had decreased expression in MCF7/PacR cells. On the other hand, mitochondrial carbamoyl-phosphate synthetase 1 (CPS1) and ATPase family AAA-domain containing protein 3A and 3B (ATAD3A, ATAD3B) were overexpressed in MCF7/PacR cells. Further, we showed that there was no difference in localization of CPS1 in MCF7 and MCF7/PacR cells. We demonstrated a significant increase in the number of CPS1 positive MCF7/PacR cells, using FACS analysis, compared to the number of CPS1 positive MCF7 cells. Silencing of CPS1 expression by specific siRNA had no significant effect on the resistance of MCF7/PacR cells to paclitaxel. To summarize, we identified several novel proteins of a mitochondrial fraction whose role in acquired resistance to paclitaxel in breast cancer cells should be further assessed.

Implications of Cardio-Respiratory Fitness on the Performance of Exercise Tests.

In 2016, the American Heart Association (AHA) produced a position paper on cardiorespiratory fitness (CRF) which defined CRF as the most important cardiac risk factor in the assessment of prognosis in a wide variety of clinical states [1]. The aim of the paper was to improve patient management and to encourage life-style based strategies designed to improve cardiovascular risk. The authors showed that: In this Brief Communication, we expand on how CRF can be assessed and reported in exercise testing.

Mild Depression Predicts Long-Term Mortality After Acute Myocardial Infarction: A 25-Year Follow-Up.

BACKGROUND: Past studies have found that depression is an independent predictor of death in patients after acute myocardial infarction (AMI). Our aim was to investigate whether the adverse effect upon mortality of depression, including mild levels, persisted up to 25 years. METHODS: We used an historical design to study patients who had been consecutively admitted to hospital after transmural AMI during the 1980s and enrolled in an exercise training trial. The Beck Depression Inventory (BDI) was administered to 188 patients in the third week after hospital admission. Scores were trichotomised and classified as low (0-5), mild (6-9) or moderate to severe (≥10) depression. The Australian National Death Index was used to determine mortality status. Cox proportional-hazards modelling was undertaken to determine the relationship between the trichotomised BDI-I scores and all-cause mortality over five time periods up to 25 years. RESULTS: The mean age of patients was 54.15 years. One hundred fourteen (114) (60.4%) had low or no depression, 47 (25.2%) mild depression and 27 (14.3%) moderate to severe depression. The mortality status of 185 (98.4%) patients was established. Depression was a significant predictor of death, independently of age and severity of myocardial infarction, at 5, 10 and 15 years but not at 20 or 25 years. Patients with mild depression had greater mortality than those with low or moderate to severe depression. CONCLUSIONS: Early identification of depression, including milder levels, is important since patients remain at increased risk for many years. They require ongoing monitoring and appropriate treatment.

Substituents at the C3' and C3'N positions are critical for taxanes to overcome acquired resistance of cancer cells to paclitaxel.

We tested the role of substituents at the C3' and C3'N positions of the taxane molecule to identify taxane derivatives capable of overcoming acquired resistance to paclitaxel. Paclitaxel-resistant sublines SK-BR-3/PacR and MCF-7/PacR as well as the original paclitaxel-sensitive breast cancer cell lines SK-BR-3 and MCF-7 were used for testing. Increased expression of the ABCB1 transporter was found to be involved in the acquired resistance. We tested three groups of taxane derivatives: (1) phenyl group at both C3' and C3'N positions, (2) one phenyl at one of the C3' and C3'N positions and a non-aromatic group at the second position, (3) a non-aromatic group at both C3' and C3'N positions. We found that the presence of phenyl groups at both C3' and C3'N positions is associated with low capability of overcoming acquired paclitaxel resistance compared to taxanes containing at least one non-aromatic substituent at the C3' and C3'N positions. The increase in the ATPase activity of ABCB1 transporter after the application of taxanes from the first group was found to be somewhat higher than after the application of taxanes from the third group. Molecular docking studies demonstrated that the docking score was the lowest, i.e. the highest binding affinity, for taxanes from the first group. It was intermediate for taxanes from the second group, and the highest for taxanes from the third group. We conclude that at least one non-aromatic group at the C3' and C3'N positions of the taxane structure, resulting in reduced affinity to the ABCB1 transporter, brings about high capability of taxane to overcome acquired resistance of breast cancer cells to paclitaxel, due to less efficient transport of the taxane compound out of the cancer cells.

Cardiac Society of Australia and New Zealand Position Statement: Coronary Artery Calcium Scoring.

Coronary Artery Calcium Scoring (CAC) is a non-invasive quantitation of coronary artery calcification using computed tomography (CT). It is a marker of atherosclerotic plaque burden and an independent predictor of future myocardial infarction and mortality. Coronary Artery Calcium Scoring provides incremental risk information beyond traditional risk calculators (eg. Framingham Risk Score). Its use for risk stratification is confined to primary prevention of cardiovascular events, and can be considered as "individualised coronary risk scoring" for those not considered to be of high or low risk. Medical practitioners should carefully counsel patients prior to CAC. Coronary Artery Calcium Scoring should only be undertaken if an alteration in therapy including embarking on pharmacotherapy is being considered based on the test result. Patient Groups to Consider Coronary Calcium Scoring: Patient Groups in Whom Coronary Calcium Scoring Should Not be Considered: Coronary Artery Calcium Scoring is not recommended for patients who are: Interpretation of CAC CAC=0 A zero score confers a very low risk of death, <1% at 10 years. CAC=1-100 Low risk, <10% CAC=101-400 Intermediate risk, 10-20% CAC=101-400 & >75th centile. Moderately high risk, 15-20% CAC >400 High risk, >20% Management Recommendations Based on CAC Optimal diet and lifestyle measures are encouraged in all risk groups and form the basis of primary prevention strategies. Patients with moderately-high or high risk based on CAC score are recommended to receive preventative medical therapy such as aspirin and statins. The evidence for pharmacotherapy is less robust in patients at intermediate levels of CAC 100-400, with modest benefit for aspirin use; though statins may be reasonable if they are above 75th centile. Aspirin and statins are generally not recommended in patients with CAC <100. Repeat CAC Testing In patients with a CAC of 0, a repeat CAC may be considered in 5 years but not sooner. In patients with positive calcium score, routine re-scanning is not currently recommended. However, an annual increase in CAC of >15% or annual increase of CAC >100 units are predictive of future myocardial infarction and mortality. Cost Effectiveness of CAC Based Primary Prevention Recommendations: There is currently no data in Australia and New Zealand that CAC is cost-effective in informing primary prevention decisions. Given the cost of testing is currently borne entirely by the patient, discussion regarding the implications of CAC results should occur before CAC is recommended and undertaken.

SMARTphone-based, early cardiac REHABilitation in patients with acute coronary syndromes [SMART-REHAB Trial]: a randomized controlled trial protocol.

BACKGROUND: There are well-documented treatment gaps in secondary prevention of coronary heart disease and no clear guidelines to assist early physical activity after acute coronary syndromes (ACS). Smartphone technology may provide an innovative platform to close these gaps. This paper describes the study design of a randomized controlled trial assessing whether a smartphone-based secondary prevention program can facilitate early physical activity and improve cardiovascular health in patients with ACS. METHODS: We have developed a multi-faceted, patient-centred smartphone-based secondary prevention program emphasizing early physical activity with a graduated walking program initiated on discharge from ACS admission. The program incorporates; physical activity tracking through the smartphone's accelerometer with interactive feedback and goal setting; a dynamic dashboard to review and optimize cardiovascular risk factors; educational messages delivered twice weekly; a photographic food diary; pharmacotherapy review; and support through a short message service. The primary endpoint of the trial is change in exercise capacity, as measured by the change in six-minute walk test distance at 8-weeks when compared to baseline. Secondary endpoints include improvements in cardiovascular risk factor status, psychological well-being and quality of life, medication adherence, uptake of cardiac rehabilitation and re-hospitalizations. DISCUSSION: This randomized controlled trial will use a smartphone-phone based secondary prevention program to emphasize early physical activity post-ACS. It will provide evidence regarding the feasibility and utility of this innovative platform in closing the treatment gaps in secondary prevention. TRIAL REGISTRATION: The trial was retrospectively registered in the Australian New Zealand Clinical Trials Registry (ANZCTR) on April 4, 2016. The registration number is ACTRN12616000426482 .

p38 MAPK Is Activated but Does Not Play a Key Role during Apoptosis Induction by Saturated Fatty Acid in Human Pancreatic ß-Cells.

Saturated stearic acid (SA) induces apoptosis in the human pancreatic ß-cells NES2Y. However, the molecular mechanisms involved are unclear. We showed that apoptosis-inducing concentrations of SA activate the p38 MAPK signaling pathway in these cells. Therefore, we tested the role of p38 MAPK signaling pathway activation in apoptosis induction by SA in NES2Y cells. Crosstalk between p38 MAPK pathway activation and accompanying ERK pathway inhibition after SA application was also tested. The inhibition of p38 MAPK expression by siRNA silencing resulted in a decrease in MAPKAPK-2 activation after SA application, but it had no significant effect on cell viability or the level of phosphorylated ERK pathway members. The inhibition of p38 MAPK activity by the specific inhibitor SB202190 resulted in inhibition of MAPKAPK-2 activation and noticeable activation of ERK pathway members after SA treatment but in no significant effect on cell viability. p38 MAPK overexpression by plasmid transfection produced an increase in MAPKAPK-2 activation after SA exposure but no significant influence on cell viability or ERK pathway activation. The activation of p38 MAPK by the specific activator anisomycin resulted in significant activation of MAPKAPK-2. Concerning the effect on cell viability, application of the activator led to apoptosis induction similar to application of SA (PARP cleavage and caspase-7, -8, and -9 activation) and in inhibition of ERK pathway members. We demonstrated that apoptosis-inducing concentrations of SA activate the p38 MAPK signaling pathway and that this activation could be involved in apoptosis induction by SA in the human pancreatic ß-cells NES2Y. However, this involvement does not seem to play a key role. Crosstalk between p38 MAPK pathway activation and ERK pathway inhibition in NES2Y cells seems likely. Thus, the ERK pathway inhibition by p38 MAPK activation does not also seem to be essential for SA-induced apoptosis.

The role of individual caspases in cell death induction by taxanes in breast cancer cells.

BACKGROUND: In previous study we showed that caspase-2 plays the role of an apical caspase in cell death induction by taxanes in breast cancer cells. This study deals with the role of other caspases. We tested breast cancer cell lines SK-BR-3 (functional caspase-3) and MCF-7 (nonfunctional caspase-3). METHODS AND RESULTS: Using western blot analysis we demonstrated the activation of initiator caspase-8 and -9 as well as executioner caspase-6 and -7 in both tested cell lines after application of taxanes (paclitaxel, SB-T-1216) at death-inducing concentrations. Caspase-3 activation was also found in SK-BR-3 cells. Employing specific siRNAs after taxane application, suppression of caspase-3 expression significantly increased the number of surviving SK-BR-3 cells. Inhibition of caspase-7 expression also increased the number of surviving SK-BR-3 and MCF-7 cells. On the other hand, suppression of caspase-8 and caspase-9 expression had no significant effect on cell survival. However, caspase-9 seemed to be involved in the activation of caspase-3 and caspase-7. Caspase-3 and caspase-7 appeared to activate mutually. Furthermore, we observed a significant decrease in mitochondrial membrane potential (flow cytometric analysis) and cytochrome c release (confocal microscopy, western blot after cell fractionation) from mitochondria in SK-BR-3 cells. No such changes were observed in MCF-7 cells after taxane treatment. CONCLUSION: We conclude that the activation of apical caspase-2 results in the activation of caspase-3 and -7 without the involvement of mitochondria. Caspase-9 can be activated directly via caspase-2 or alternatively after cytochrome c release from mitochondria. Subsequently, caspase-9 activation can also lead to caspase-3 and -7 activations. Caspase-3 and caspase-7 activate mutually. It seems that there is also a parallel pathway involving mitochondria that can cooperate in taxane-induced cell death in breast cancer cells.

Efficacy and feasibility of a tele-health intervention for acute coronary syndrome patients with depression: results of the "MoodCare" randomized controlled trial.

BACKGROUND: Depression is common after a cardiac event, yet there remain few approaches to management that are both effective and scalable. PURPOSE: We aimed to evaluate the 6-month efficacy and feasibility of a tele-health program (MoodCare) that integrates depression management into a cardiovascular disease risk reduction program for acute coronary syndrome patients with low mood. METHODS: A two-arm, parallel, randomized design was used comprising 121 patients admitted to one of six hospitals for acute coronary syndrome. RESULTS: Significant treatment effects were observed for Patient Health Questionnaire 9 (PHQ9) depression (mean difference [change] = -1.8; p = 0.025; effect size: d = 0.36) for the overall sample, when compared with usual medical care. Results were more pronounced effects for those with a history of depression (mean difference [change] = -2.7; p = 0.043; effect size: d = 0.65). CONCLUSIONS: MoodCare was effective for improving depression in acute coronary syndrome patients, producing effect sizes exceeding those of some face-to-face psychotherapeutic interventions and pharmacotherapy. ( TRIAL REGISTRATION NUMBER: ACTRN1260900038623.).

Radiation Therapy in the Management of Head and Neck Mucosal Melanoma.

Mucosal melanoma of the head and neck (HNMM) is a rare but highly aggressive malignancy, often diagnosed at an advanced stage with poor prognosis. This review discusses current treatment strategies, emphasizing the role of radiotherapy in managing this challenging disease. A comprehensive analysis of 33 studies provides updated information on techniques and outcomes, highlighting the consistent benefit of adjuvant radiation in improving local control. Advances in conformal techniques, such as intensity-modulated radiotherapy (IMRT), have significantly reduced toxicity rates. Preliminary data on proton and carbon ion therapies suggest the potential for further enhancement of the therapeutic ratio, despite limited availability. Although recent studies report 3-year local control rates as high as 90%, overall survival within the same time frame remains well below 50-60%, underscoring the need for continued improvement in systemic therapies to address the persistent issue of distant metastases.

A Novel Immobilization Method for the Treatment of Head and Neck Cancer Using 3D Printing.

Proper immobilization is critical for the delivery of high-quality radiation therapy. In cases when traditional immobilization is not feasible, 3-dimensional (3D) printing may provide a better-tolerated custom immobilization that is comparably effective. We present the successful treatment of a patient with inoperable oropharyngeal squamous cell carcinoma who was unable to tolerate traditional immobilization. To avoid covering the face, we created a 3D-printed cradle for the back of his head and neck. This design enabled the patient to tolerate traditional simulation scans with and without intravenous contrast and was subsequently able to undergo volumetric modulated arc therapy treatment. He successfully underwent treatment without evidence of disease more than 2 years after completion. The effect of 3D printing within the context of radiation oncology, as well as in other specialties, will undoubtedly continue to increase the variety of treatment options available to patients.

Air pollution is associated with increased incidence-rate of head and neck cancers: A nationally representative ecological study.

INTRODUCTION: Early studies show conflicting findings regarding particulate matter ≤ 2.5 µm in diameter (PM2.5) exposure and development of head and neck cancers (HNC). We analyzed the relationship between PM2.5 exposure and various types of HNC in a nationally representative ecological sample. METHODS: We determined HNC incidence in 608 US counties from 2011 to 2019 using the Surveillance, Epidemiology and End Results (SEER) Program from the National Cancer Institute. We also collected information on sociodemographic factors from SEER and data on smoking and alcohol intake from CDC data frames (county level). PM2.5 exposure levels were estimated using satellite and meteorological data via previously validated general additive models. Flexible semi-nonparametric regression models were used to test the relationship between PM2.5 exposure levels and HNC incidence, adjusting for demographics, socioeconomic factors, and comorbidity. RESULTS: Increased PM2.5 exposure levels were associated with higher incidence-rates of oral cavity and pharyngeal cancers controlling for confounders in our primary analyses (IRR = 1.04, 95 % CI 1.01, 1.07, p = 0.02 per 1 µg/m3 increase in PM2.5). This relationship was maintained after adjusting for multiple testing (Holm s method, p = 0.04) and in ordinary least squares (OLS) regression (ß = 0.17, 95 % CI 0.01, 0.57, p = 0.01). Increased exposure was also associated with other HNC: esophagus (IRR = 1.06, 95 % CI 1.01, 1.11, p = 0.02), lip (IRR = 1.16, 95 % CI 1.03, 1.31, p = 0.01), tonsil (IRR = 1.10, 95 % CI 1.03, 1.16, p < 0.01). However, these relationships were not maintained in secondary analyses. CONCLUSIONS: This nationally representative ecological study shows that increased levels of air pollution are associated with increased incidence of overall oral cavity and pharyngeal cancers in the US.

Caspase-2 is involved in cell death induction by taxanes in breast cancer cells.

BACKGROUND: We studied the role of caspase-2 in apoptosis induction by taxanes (paclitaxel, novel taxane SB-T-1216) in breast cancer cells using SK-BR-3 (nonfunctional p53, functional caspase-3) and MCF-7 (functional p53, nonfunctional caspase-3) cell lines. RESULTS: Both taxanes induced apoptosis in SK-BR-3 as well as MCF-7 cells. Caspase-2 activity in SK-BR-3 cells increased approximately 15-fold within 48 h after the application of both taxanes at the death-inducing concentration (100 nM). In MCF-7 cells, caspase-2 activity increased approximately 11-fold within 60 h after the application of taxanes (300 nM). Caspase-2 activation was confirmed by decreasing levels of procaspase-2, increasing levels of cleaved caspase-2 and the cleavage of caspase-2 substrate golgin-160. The inhibition of caspase-2 expression using siRNA increased the number of surviving cells more than 2-fold in MCF-7 cells, and at least 4-fold in SK-BR-3 cells, 96 h after the application of death-inducing concentration of taxanes. The inhibition of caspase-2 expression also resulted in decreased cleavage of initiator caspases (caspase-8, caspase-9) as well as executioner caspases (caspase-3, caspase-7) in both cell lines after the application of taxanes. In control cells, caspase-2 seemed to be mainly localized in the nucleus. After the application of taxanes, it was released from the nucleus to the cytosol, due to the long-term disintegration of the nuclear envelope, in both cell lines. Taxane application led to some formation of PIDDosome complex in both cell lines within 24 h after the application. After taxane application, p21WAF1/CIP1 expression was only induced in MCF-7 cells with functional p53. However, taxane application did not result in a significant increase of PIDD expression in either SK-BR-3 or MCF-7 cells. The inhibition of RAIDD expression using siRNA did not affect the number of surviving SK-BR-3 and MCF-7 cells after taxane application at all. CONCLUSION: Caspase-2 is required, at least partially, for apoptosis induction by taxanes in tested breast cancer cells. We suggest that caspase-2 plays the role of an apical caspase in these cells. Caspase-2 seems to be activated via other mechanism than PIDDosome formation. It follows the release of caspase-2 from the nucleus to the cytosol.