Identifying and characterising dormancy in prostate cancer cells

Prostate cancer is the second leading cause of cancer death in men in the UK. Around 30% of patients with apparently localized disease at diagnosis and who receive radical surgery to remove the primary tumour, will present with skeletal metastasis, in many cases >5 years after initial treatment. This suggests that prostate cancer cells can persist in a dormant or indolent state, undetected in patients for many years. To investigate states of dormancy in prostate cancer cells, the growth of human prostate cancer cell lines in vitro was examined to test the hypothesis that there are sub-populations of dormant cells present even within widely used, rapidly proliferating cell lines. My studies successfully identified these cells, which were then extensively characterised. Parallel studies in our laboratory indicated that these cells had greater potency than other cells in the initiation of metastatic lesions in xenograft models. To identify dormant cells in three prostate cancer cell lines: PC-3NW1, LNCaP and C42B4, were stained with the lipophilic membrane dye Vybrant DiD. The retention of this dye was used as a marker of dormant or slow-cycling cells. Flow cytometry analysis and fluorescent microscopy identified a dormant cell sub-population in all three prostate cancer cell lines at a frequency of <2% after 14 days in culture. Dormancy was not an intrinsic characteristic of this sub-population, as this phenotype could re-emerge in cultures of separated re-cultured non-dormant cells. The frequency of dormant cells in cultures could be altered by changes in culture conditions and when isolated these cells could be released from dormancy to form colonies. Gene expression profiles for the non-dormant and dormant sub-population were compared by RT-qPCR and a set of differentially expressed, dormancy specific genes identified. Immunofluorescence microscopy was used to assess whether the observed differences in gene expression between populations were reflected in altered specific protein levels. The presence of a specific marker of dormancy, CXCR4, identified by these experiments, was then evaluated in 75 primary patient samples by immunohistochemistry. Elevated CXCR4, as measure by immunohistochemistry, in patient samples correlated to other indicators of poor prognosis but did not independently predict the presence of metastases

Mitotic quiescence, but not unique "stemness," marks the phenotype of bone metastasis-initiating cells in prostate cancer

This study aimed to identify subpopulations of prostate cancer cells that are responsible for the initiation of bone metastases. Using rapidly dividing human prostate cancer cell lines, we identified mitotically quiescent subpopulations (<1%), which we compared with the rapidly dividing populations for patterns of gene expression and for their ability to migrate to the skeletons of athymic mice. The study used 2-photon microscopy to map the presence/distribution of fluorescently labeled, quiescent cells and luciferase expression to determine the presence of growing bone metastases. We showed that the mitotically quiescent cells were very significantly more tumorigenic in forming bone metastases than fast-growing cells (55 vs. 15%) and had a unique gene expression profile. The quiescent cells were not uniquely stem cell like, with no expression of CD133 but had the same level expression of other putative prostate stem cell markers (CD44 and integrins α2/β1), when compared to the rapidly proliferating population. In addition, mitotic quiescence was associated with very high levels of C-X-C chemokine receptor type 4 (CXCR4) production. Inhibition of CXCR4 activity altered the homing of quiescent tumor cells to bone. Our studies suggest that mitotic dormancy is a unique phenotype that facilitates tumor cell colonization of the skeleton in prostate cancer.—Wang, N., Docherty, F., Brown, H. K., Reeves, K., Fowles, A., Lawson, M., Ottewell, P. D., Holen, I., Croucher, P. I., Eaton, C. L. Mitotic quiescence, but not unique “stemness,” marks the phenotype of bone metastasis-initiating cells in prostate cancer

'Yeah that made a big difference!': The importance of the relationship between health professionals and fathers who have a child with Down Syndrome

Evidence suggests that medical services do not reflect the increased involvement of fathers in childcare, a discrepancy that can often lead to feelings of exclusion and inequality. Fathers who have a child with Down syndrome may encounter many different health professionals during their child’s life, therefore it is important to consider this relationship, and investigate the factors that influence their experiences. This is particularly important because the limited research focusing on fathers suggest that those who have a child with Down syndrome can experience increased stress levels and lasting feelings of loss and grief. It is therefore important to address their relationships with health professionals, as these may be a significant resource to prevent these feelings. This study used interpretative phenomenological analysis (IPA) to explore the experiences of seven fathers who have a child with Down syndrome, focusing on their interactions with health professionals. The analysis showed that the major factors associated with negative experiences were feelings of exclusion, receiving overly negative information about the condition and a perceived lack of on-going support. Positive experiences were associated with being made to feel like an equal parent, being given direct/clear information and being congratulated on the birth of their child. These results provide an insight into what fathers expect in terms of their own and their child’s care and highlight that health professionals have an important and extensive role in influencing fathers’ experiences of Down syndrome

The frequency of osteolytic bone metastasis is determined by conditions of the soil, not the number of seeds; evidence from in vivo models of breast and prostate cancer

Background While both preclinical and clinical studies suggest that the frequency of growing skeletal metastases is elevated in individuals with higher bone turnover, it is unclear whether this is a result of increased numbers of tumour cells arriving in active sites or of higher numbers of tumour cells being induced to divide by the bone micro-environment. Here we have investigated how the differences in bone turnover affect seeding of tumour cells and/or development of overt osteolytic bone metastasis using in vivo models of hormone-independent breast and prostate cancer. Methods Cohorts of 6 (young) and 16 (mature)-week old BALB/c nude mice were culled 1, 7 and 21 days after received intracardiac injection of luciferase expressing human prostate (PC3) or breast cancer (MDA-MB-231) cell lines labelled with a fluorescent cell membrane dye (Vybrant DiD). The presence of growing bone metastases was determined by bioluminescence using an in vivo imaging system (IVIS) and followed by anatomical confirmation of tumour metastatic sites post mortem, while the presence of individual fluorescently labelled tumour cells was evaluated using two-photon microscopy ex vivo. The bone remodelling activities were compared between young and mature naïve mice (both male and female) using micro-CT analysis, ELISA and bone histomorphometry. Results Both prostate and breast cancer cells generated higher numbers of overt skeletal lesions in young mice (~80%) than in mature mice (~20%). Although mature mice presented with fewer overt bone metastases, the number of tumour cells arriving/colonizing in the tibias was comparable between young and mature animals. Young naïve mice had lower bone volume but higher bone formation and resorption activities compared to mature animals. Conclusions Our studies suggest that higher frequencies of growing osteolytic skeletal metastases in these models are linked to increased bone turnover and not to the initial number of tumour cells entering the bone microenvironment