Influence of topoisomerase II inhibitors and ionizing radiation on growth arrest and cell death pathways in the breast tumor cell

Is Season of Diagnosis a Predictor of Cancer Survival? Results from the Zurich Cancer Registry

In Switzerland, there is a large seasonal variation in sunlight, and vitamin D deficiency is relatively common during winter. The season of diagnosis may be linked to cancer survival via vitamin D status. Using data from the Cancer Registry of Zurich, Zug, Schaffhausen, and Schwyz with more than 171,000 cancer cases registered since 1980, we examined the association of the season of diagnosis with survival for cancers including prostate (ICD10 code C61; International Categorization of Diseases, version 10), breast (C50), colorectal (C18-21), lung (C34), melanoma (C43), and all sites combined. Cox proportional hazards regression models were used to assess the differences in the all-cause mortality by the season of the diagnosis. Winter was used as the reference season. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated for all the cancers combined (excluding nonmelanoma skin cancer) and for prostate (in men), breast (in women), colorectal, lung cancer, and melanomas, separately. A diagnosis in summer and/or autumn was associated with improved survival in all the sites combined for both sexes (men: HR 0.97 [95% CI 0.96-0.99]; women: HR 0.97 [95% CI 0.94-0.99]) and in colorectal (HR 0.91 [95% CI 0.84-0.99]), melanoma (HR 0.81 [95% CI 0.65-1.00]), and breast cancer (HR 0.91 [95% CI 0.94-0.99]) in women. Our study results suggest that a cancer diagnosis in summer and/or autumn is associated with a better prognosis. The improved seasonal survival coincides with the seasonal variation of sun-induced vitamin D, and vitamin D may play a protective and beneficial role in cancer survival.

DIVERSet JAG Compounds Inhibit Topoisomerase II and Are Effective Against Adult and Pediatric High-Grade Gliomas

High-grade gliomas (HGGs) are aggressive primary brain tumors with local invasive growth and poor clinical prognosis in both adult and pediatric patients. Clinical response is compounded by resistance to standard frontline antineoplastic agents, an absence of novel therapeutics, and poor in vitro models to evaluate these. We screened a range of recently identified anticancer compounds in conventional adult, pediatric, and new biopsy-derived HGG models. These in vitro lines showed a range of sensitivity to standard chemotherapeutics, with varying expression levels of the prognostic markers hypoxia-induced factor (HIF) 1α and p53. Our evaluation of lead DIVERSet library compounds identified that JAG-6A, a compound that was significantly more potent than temozolomide or etoposide, was effective against HGG models in two-dimensional and three-dimensional systems; mediated this response by the potent inhibition of topoisomerase Iiα; remained effective under normoxic and hypoxic conditions; and displayed limited toxicity to non-neoplastic astrocytes. These data suggest that JAG-6A could be an alternative topoisomerase IIα inhibitor and used for the treatment of HGG.

Cellular prion protein contributes to LS 174T colon cancer cell carcinogenesis by increasing invasiveness and resistance against doxorubicin-induced apoptosis

As the cellular prion protein (PrP(C)) has been implicated in carcinogenesis, we aimed to investigate the effects of cancer cell-specific PrP(C) overexpression from the invasion, metastasis, and apoptosis aspects, by performing cell motility assays, cell proliferation assays under anchorage-dependent and anchorage-independent conditions, and apoptosis evasion when subjected to multiple anti-cancer drugs. Overexpression of PrP(C) in LS 174T was achieved by stable transfection. PrP(C) overexpression was shown to increase cell proliferation in anchorage-dependent and anchorage-independent manners, as shown by more viable cells in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, more colonies formed in soft agar assay and increased resistance to anoikis in poly-2-hydroxyethyl methacrylate-coated surface. PrP(C) overexpression also increased cell motility and invasiveness of LS 174T. Cell adhesion to extracellular matrix using collagen- and fibronectin-coated surfaces revealed increased cell attachment in LS 174T cells overexpressing PrP(C). Analysis of apoptotic and necrotic cells by propidium iodide/annexin V-fluorescein isothiocyanate microscopy and 7-amino-actinomycin D/annexin V-phycoerythrin flow cytometry revealed that PrP(C) overexpression attenuated doxorubicin-induced apoptosis. Human apoptosis antibody array with 35 apoptosis-related proteins revealed that three inhibitor of apoptosis proteins (IAPs)-survivin, X-linked inhibitor of apoptosis protein (XIAP), and cellular inhibitor of apoptosis protein-1 (cIAP-1)-were upregulated in LS 174T cells overexpressing PrP(C) in doxorubicin-induced apoptosis. In conclusion, the overexpression of PrP(C) could enhance the invasiveness and survival of LS 174T colorectal cancer cells, indicating that PrP(C) plays a role in colorectal cancer biology.

Cell intrinsic and extrinsic activators of the unfolded protein response in cancer: Mechanisms and targets for therapy

A variety of cell intrinsic or extrinsic stresses evoke perturbations in the folding environment of the endoplasmic reticulum (ER), collectively known as ER stress. Adaptation to stress and re-establishment of ER homeostasis is achieved by activation of an integrated signal transduction pathway called the unfolded protein response (UPR). Both ER stress and UPR activation have been implicated in a variety of human cancers. Although at early stages or physiological conditions of ER stress, the UPR generally promotes survival, when the stress becomes more stringent or prolonged, its role can switch to a pro-cell death one. Here, we discuss historical and recent evidence supporting an involvement of the UPR in malignancy, describe the main mechanisms by which tumor cells overcome ER stress to promote their survival, tumor progression and metastasis and discuss the current state of efforts to develop therapeutic approaches of targeting the UPR.

Seasonality pattern of breast, colorectal, and prostate cancer is dependent on latitude

Background

The season of diagnosis of several forms of cancer has been observed to impact survival, supporting the hypothesis that vitamin D₃ has a protective role in cancer survival. All previous studies demonstrating this seasonality were performed in European populations residing at latitudes upwards of 50°N. This study investigated whether seasonality of prognosis persists in populations residing in the lower latitudes of the contiguous United States (Latitude 21°N to 48°N).

Material/Methods

The 5-year survival data of 19 204 female breast cancer, 6740 colorectal cancer, and 1644 prostate cancer cases was analyzed.

Results

Female breast cancer patients exhibited improved survival when diagnosed in the summer as compared to the winter at all latitudes (Hazard Ratio [HR]: 0.940, 95%; Confidence Interval [CI]: 0.938 to 0.941, P=0.002). Colorectal cancer and prostate cancer also exhibited a similar seasonal pattern (HR: 0.978, 95% CI: 0.975 to 0.980, P=0.008 and HR: 0.935, 95%, CI 0.929 to 0.943, P=0.006), respectively, when the analysis was restricted to northern regions.

Conclusions

These observations contribute to the mounting evidence that vitamin D₃ may affect the progression of cancer. Data also suggest that vitamin D₃ status at the onset of treatment may synergistically improve the prognosis of several cancer types.

Doxorubicin induces cell death in breast cancer cells regardless of Survivin and XIAP expression levels

Breast cancer is the leading cause of deaths in women around the world. Resistance to therapy is the main cause of treatment failure and still little is known about predictive biomarkers for response to systemic therapy. Increasing evidence show that Survivin and XIAP overexpression is closely associated with chemoresistance and poor prognosis in breast cancer. However, their impact on resistance to doxorubicin (dox), a chemotherapeutic agent widely used to treat breast cancer, is poorly understood. Here, we demonstrated that dox inhibited cell viability and induced DNA fragmentation and activation of caspases-3, -7 and -9 in the breast cancer-derived cell lines MCF7 and MDA-MB-231, regardless of different p53 status. Dox exposure resulted in reduction of Survivin and XIAP mRNA and protein levels. However, when we transfected cells with a Survivin-encoding plasmid, we did not observe a cell death-resistant phenotype. XIAP and Survivin silencing, either alone or in combination, had no effect on breast cancer cells sensitivity towards dox. Altogether, we demonstrated that breast cancer cells are sensitive to the chemotherapeutic agent dox irrespective of Survivin and XIAP expression levels. Also, our findings suggest that dox-mediated modulation of Survivin and XIAP might sensitize cells to taxanes when used in a sequential regimen.

CD24(-/low) stem-like breast cancer marker defines the radiation-resistant cells involved in memorization and transmission of radiation-induced genomic instability

A growing body of evidence attributes properties of chemo- and/or radiation-resistance to cancer stem cells (CSCs). Moreover, non-targeted delayed effects such as genomic instability, transmitted through many generations, can be observed in the progeny of surviving irradiated cells. As a consequence, we propose that radiation-resistance properties associated to CSCs could confer a key role to this subpopulation in the transmission of genomic instability. To test this hypothesis, we searched the CSC markers associated to radiation-resistance in breast cancer cell lines and studied the role of the resistant cells in the transmission of genomic instability. First, we show that irradiation induces a 2-4 weeks period of intense cell death leading to the emergence of chromosomal unstable cells during more than 35 population doublings. Then, among seven breast CSC markers, we identify CD24(-/low) labelling as a marker of radiation-resistance. We demonstrate that CD24(+) progeny of irradiated cells exclusively descends from CD24(-/low) cells. Finally, we show that delayed chromosomal instability is only expressed by CD24(+) cells, but is transmitted by stable surviving CD24(-/low) cells. So, for the first time a CSC marker, CD24, is associated with the transmission of genomic instability. This work may assign a new deleterious role to breast CSCs in aggressive recurrence after radiotherapy, as the transmitted genomic instability potentially leads tumour cells to acquire more aggressive characteristics.

Changes in risk of death from breast cancer with season and latitude

The Norwegian counties can conveniently be divided in three groups with different annual UV exposures and different incidence rates of squamous cell carcinoma (SCC) of the skin. In view of the hypothesis that latitude and season of diagnosis may play a role for breast cancer progression, the prognosis of breast cancer as determined for summer and winter diagnosis, were evaluated in the three residential regions. Two age groups were analysed separately (stratification at 50 years). For all regions, and for all ages, the prognosis was best for women diagnosed in the summer season (Relative risk (RR) of death was 15-25% lower for summer diagnosis versus winter diagnosis). There was no significant seasonal variation of the number of new cases. For women diagnosed before the age of 50, a geographical gradient in cancer prognosis was also found (RR of death 0.6, 95% CI: 0.5-0.7 for cases diagnosed in southeast Norway and RR of death 0.8, 95% CI: 0.6-1.1 for diagnosis in the north of Norway). This is in agreement with a 1.5 times larger annual UV exposures and 3-4 times larger incidence rates of SCC in the southeast region when compared with the north region. For women diagnosed after the age of 50, no significant difference was found between the three regions. Despite a 17% higher vitamin D intake from food in north of Norway no difference in cancer survival was found for diagnosis during winter (when no significant differences in the levels of UV exposure can be detected between regions). The overall data support our earlier hypothesis that season of diagnosis and therapy start improves the survival for breast cancer.

Doxorubicin-induced activation of protein kinase D1 through caspase-mediated proteolytic cleavage: identification of two cleavage sites by microsequencing

Recent studies have demonstrated the importance of protein kinase D (PKD) in cell proliferation and apoptosis. Here, we report that in vitro cleavage of recombinant PKD1 by caspase-3 generates two alternative active PKD fragments. N-terminal sequencing of these fragments revealed two distinct caspase-3 cleavage sites located between the acidic and pleckstrin homology (PH) domains of PKD1. Moreover, we present experimental evidence that PKD1 is an in vitro substrate for both initiator and effector caspases. During doxorubicin-induced apoptosis, a zVAD-sensitive caspase induces cleavage of PKD1 at two sites, generating fragments with the same molecular masses as those determined in vitro. The in vivo caspase-dependent generation of the PKD1 fragments correlates with PKD1 kinase activation. Our results indicate that doxorubicin-mediated apoptosis induces activation of PKD1 through a novel mechanism involving the caspase-mediated proteolysis.