Exploring the impact of anti-oestrogen resistance on the capacity of breast cancer cells to modulate bone cell function and their sensitivity to bisphosphonates

Acquired resistance to endocrine therapy is a major limiting factor for their clinical effectiveness, resulting in disease relapse and an associated poor prognosis. Acquired resistance is also associated with the development of an invasive and migratory phenotype in vitro that may promote metastatic spread in vivo of which bone is the most frequent site. However, it is not currently known whether endocrine resistance affects the ability of breast cancer cells to modulate bone cell function important in establishing bone metastases or whether a resistant phenotype alters sensitivity to agents commonly used to treat bone metastasis such as bisphosphonates. Thus, this thesis aimed to explore the bone cell modulatory function of endocrine resistant and sensitive breast cancer cells along with their sensitivity to the bisphosphonate, zoledronic acid. This thesis demonstrated that breast cancer cells were able to directly induce osteoclast differentiation from both murine and human precursor cells. Importantly, this effect was more prevalent in tamoxifen resistant and triple negative breast cancer subtypes. Our data also suggested that the breast cancer-mediated osteoclastogenic effect involved Src kinase, whilst bisphosphonates acted as anti-tumour agents in tamoxifen resistant cells through inhibition of EGFR/AKT/mTOR pathway. In conclusion, this thesis suggests that acquisition of endocrine resistance confers a bone modulatory ability to breast cancer cells that may contribute to the development of bone metastases. However, this thesis reports the novel finding that acquired endocrine resistance augments the sensitivity of breast cancer cells to bisphosphonates, thus representing an opportunity to target resistant disease clinically

Anaerobic co-digestion of swine manure and crude glycerol derived from animal fat - Effect of hydraulic retention time

Crude glycerol (CG), an abundant by-product of bio-diesel production, has been identified as a suitable co-substrate for improving the biogas production of livestock manure through anaerobic digestion (AD). In this study, the potential of utilizing CG generated from the esterification of animal fats for biogas production was studied in both batch and continuous AD experiments, with emphasis on the importance of the hydraulic retention time (HRT). Batch experiments showed that the limiting step in the methane production rate during CG mono-digestion was the 1,3-propanediol uptake. Additionally, biochemical methane potential tests indicated that the addition of 1% w/w CG to swine manure-AD is more efficient in terms of percent of theoretical amount of methane obtained than the addition of 3% w/w. However, in continuous experiments, co-digestion of manure with 3% w/w CG did not exhibit any sign of inhibition within the HRTs tested (17–22 days). Moreover, a 222% increase of biogas productivity was observed with 3% CG supplementation at an HRT of 17 days, in contrast to a 146% increase at an HRT of 22 days. Based on this, and on the similar efficiency of soluble COD removal among the processes (ca. 93%), it was shown that it is possible to reduce the HRT without affecting negatively the efficiency of conversion of manure. Moreover, it was shown that CG from 2nd generation biodiesel based on animal fat, is a suitable feedstock for boosting the methane production of manure-based biogas plants

Improving the Anaerobic Digestion of Swine Manure through an Optimized Ammonia Treatment: Process Performance, Digestate and Techno-Economic Aspects

Swine manure mono-digestion results in relatively low methane productivity due to the low degradation rate of its solid fraction (manure fibers), and due to the high ammonia and water content. The aqueous ammonia soaking (AAS) pretreatment of manure fibers has been proposed for overcoming these limitations. In this study, continuous anaerobic digestion (AD) of manure mixed with optimally AAS-treated manure fibers was compared to the AD of manure mixed with untreated manure fibers. Due to lab-scale pumping restrictions, the ratio of AAS-optimally treated manure fibers to manure was only 1/3 on a total solids (TS) basis. However, the biogas productivity and methane yield were improved by 17% and 38%, respectively, also confirming the predictions from a simplified 1st order hydrolysis model based on batch experiments. Furthermore, an improved reduction efficiency of major organic components was observed for the digester processing AAS-treated manure fibers compared to the non-treated one (e.g., 42% increased reduction for cellulose fraction). A preliminary techno-economic analysis of the proposed process showed that mixing raw manure with AAS manure fibers in large-scale digesters could result in a 72% increase of revenue compared to the AD of manure mixed with untreated fibers and 135% increase compared to that of solely manure

The Exposure of Breast Cancer Cells to Fulvestrant and Tamoxifen Modulates Cell Migration Differently

There is no doubt that there are increased benefits of hormonal therapy to breast cancer patients; however, current evidence suggests that estrogen receptor (ER) blockage using antiestrogens is associated with a small induction of invasiveness in vitro. The mechanism by which epithelial tumor cells escape from the primary tumor and colonize to a distant site is not entirely understood. This study investigates the effect of two selective antagonists of the ER, Fulvestrant (Fulv) and Tamoxifen (Tam), on the invasive ability of breast cancer cells. We found that 17β-estradiol (E2) demonstrated a protective role regarding cell migration and invasion. Fulv did not alter this effect while Tam stimulated active cell migration according to an increase in Snail and a decrease in E-cadherin protein expression. Furthermore, both tested agents increased expression of matrix metalloproteinases (MMPs) and enhanced invasive potential of breast cancer cells. These changes were in line with focal adhesion kinase (FAK) rearrangement. Our data indicate that the anti-estrogens counteracted the protective role of E2 concerning migration and invasion since their effect was not limited to antiproliferative events. Although Fulv caused a less aggressive result compared to Tam, the benefits of hormonal therapy concerning invasion and metastasis yet remain to be investigated