Abstract 2443: Oxygen metabolism and hypoxia tolerance in organoid models of pancreatic ductal adenocarcinoma

Background: Pancreatic Ductal Adenocarcinoma (PDAC) has extremely heterogeneous hypoxic microenvironments across patients and high levels of hypoxia are correlated with increased tumor aggressiveness and resistance to therapy. However, the underlying genetic contributors to variations in hypoxia and its importance to the disease is currently unknown. We hypothesize that genetic mutations in PDAC associated with two principal factors - oxygen metabolism and hypoxia tolerance - influence the steady state levels of hypoxia in individual tumors. The demand for oxygen, which is influenced by genetic driven changes in cellular metabolism, define the levels and steepness of hypoxia gradients around perfused vessels. Tolerance to hypoxia determines the time tumor cells can survive in severe microenvironments depleted of oxygen and other nutrients. Both factors are affected by the activation of adaptive hypoxia stress response pathways including the HIF, UPR, and autophagy pathways. Method: We developed patient-derived-organoids from PDAC tumors for in vitro studies of oxygen metabolism and glycolytic rates using the Seahorse XF96. We also characterized hypoxia tolerance through monitoring of organoid growth and secondary growth under defined levels of oxygenation. In addition, we have developed an immunofluorescence image analysis pipeline to evaluate in vivo oxygen demand/consumption through the quantification of oxygen and proliferation gradients around perfused blood vessels. Results: We observed significant heterogeneities in oxygen metabolism and hypoxia tolerance across our patient derived organoid models. We also demonstrated the importance of PERK/UPR pathway in mediating both oxygen metabolism and hypoxia tolerance through regulation of ULK1, a kinase involved in the initiation of autophagy. Inhibition or knockdown of ULK1 decreased cell survival and correspondingly sensitized cells to hypoxia in organoid and tumor models. This is accompanied by accumulation of mitochondria and a corresponding increase in oxygen consumption, resulting in increased development of hypoxic cells. Conclusion: These experiments demonstrate the dual importance of oxygen metabolism and hypoxia tolerance and set the stage for the evaluation of these parameters and identification of the underlying genetic drivers of the hypoxic microenvironment. These genetic markers would be used for patient-selection and development of hypoxia-targeted therapies.

Citation Format: Ji Zhang, Qingquan Liu, Dan Cojocari, Mark Zaidi, Trevor McKee, Nikolina Radulovich, Ming-Sound Tsao, David Hedley, Marianne Koritzinsky, Bradly G. Wouters. Oxygen metabolism and hypoxia tolerance in organoid models of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2443.

Magnetic, magnetocaloric and critical behavior investigation of La0.7Ca0.1Pb0.2Mn1−x−yAlxSnyO3 (x, y = 0.0, 0.05 and 0.075) prepared by a sol–gel method

A systematic study on the magnetic, magnetocaloric and critical behavior properties of polycrystalline La_0.7Ca_0.1Pb_0.2Mn_1−x−yAl_xSn_yO₃ prepared via a sol–gel method are studied.

Beyond Reproduction: Pituitary Hormone Actions on Bone

The long-held belief that pituitary hormones act solely on master targets was first questioned when we documented G protein-coupled receptors for thyroid-stimulating hormone, follicle-stimulating hormone, adrenocorticotrophic hormone, oxytocin, and vasopressin on bone cells. These evolutionarily conserved hormones and their receptors are known to have primitive roles, and exist in invertebrate species as far down as coelenterates. It is not surprising therefore that each such hormone has multiple hitherto unrecognized functions in mammalian integrative physiology, and hence, becomes a potential target for therapeutic intervention. Here we discuss the skeletal actions of pituitary hormones.

T3 Regulates a Human Macrophage-Derived TSH-β Splice Variant: Implications for Human Bone Biology

TSH and thyroid hormones (T3 and T4) are intimately involved in bone biology. We have previously reported the presence of a murine TSH-β splice variant (TSH-βv) expressed specifically in bone marrow-derived macrophages and that exerted an osteoprotective effect by inducing osteoblastogenesis. To extend this observation and its relevance to human bone biology, we set out to identify and characterize a TSH-β variant in human macrophages. Real-time PCR analyses using human TSH-β-specific primers identified a 364-bp product in macrophages, bone marrow, and peripheral blood mononuclear cells that was sequence verified and was homologous to a human TSH-βv previously reported. We then examined TSH-βv regulation using the THP-1 human monocyte cell line matured into macrophages. After 4 days, 46.1% of the THP-1 cells expressed the macrophage markers CD-14 and macrophage colony-stimulating factor and exhibited typical morphological characteristics of macrophages. Real-time PCR analyses of these cells treated in a dose-dependent manner with T3 showed a 14-fold induction of human TSH-βv mRNA and variant protein. Furthermore, these human TSH-βv-positive cells, induced by T3 exposure, had categorized into both M1 and M2 macrophage phenotypes as evidenced by the expression of macrophage colony-stimulating factor for M1 and CCL-22 for M2. These data indicate that in hyperthyroidism, bone marrow resident macrophages have the potential to exert enhanced osteoprotective effects by oversecreting human TSH-βv, which may exert its local osteoprotective role via osteoblast and osteoclast TSH receptors.

The oxytocin-bone axis

We recently demonstrated a direct action of oxytocin (OT) on skeletal homeostasis, mainly mediated through stimulation of osteoblasts (OBs) formation and through the reciprocal modulation of osteoclast (OCs) formation and function. Thus, mice lacking the hormone or its receptor develop a low turnover osteoporosis that worsens with age in both sexes. The skeletons of OT (Ot) and OT receptor (Oxtr) null mice display a pronounced decrease in vertebral and femoral trabecular volume. At the cellular level, OBs from Ot KO and Oxtr KO mice exhibit lower mineralization activity and, at the mRNA level, all master genes for osteoblast differentiation are down-regulated. Moreover, OT has dual effects on OCs: it increases osteoclast formation both directly, by activating nuclear factor kB (NFkB) and mitogen-activated protein kinase (MAPK) signalling and, indirectly, through the up-regulation of receptor activator nuclear factor-kappaB ligand synthesis by OBs. On the other hand, it inhibits bone resorption by triggering cytosolic Ca(2+) release and nitric oxide synthesis in mature OCs. OT is locally produced by osteoblasts acting as paracrine-autocrine regulators of bone formation modulated by oestrogens. The oestrogen signal involved in this feedforward circuit is nongenomic because it requires an intact MAPK kinase signal transduction pathway, instead of the classical nuclear translocation of oestrogen receptor. The ability of oestrogen to increase bone mass in vivo is to some extent OXTR-dependent. Thus, Oxtr KO mice injected 17β-oestradiol did not show any effects on bone formation parameters, whereas the same treatment increases trabecular and cortical bone in wild-type mice. An intact OT autocrine-paracrine circuit appears to be essential for optimal skeletal remodelling.

Thyroid and bone: macrophage-derived TSH-β splice variant increases murine osteoblastogenesis

It is now firmly established that TSH may influence the physiology and patho-physiology of bone by activating osteoblasts and inhibiting osteoclast activity resulting in relative osteoprotection. Whether this influence is directly exerted by pituitary-derived TSH in vivo is less certain, because we have previously reported that the suppression of pituitary TSH does not remove such protection. Here, we have characterized the functional relevance of a novel form of the TSH-β subunit, designated TSH-βv, known to be produced by murine bone marrow cells. We found that fresh bone marrow-derived macrophages (MØs) preferentially produced TSH-βv and, when cocultured with CHO cells engineered to overexpress the full-length TSH receptor, were able to generate the production of intracellular cAMP; a phenomenon not seen in control CHO cells, such results confirmed the bioactivity of the TSH variant. Furthermore, cocultures of MØs and osteoblasts were shown to enhance osteoblastogenesis, and this phenomenon was markedly reduced by antibody to TSH-β, suggesting direct interaction between MØs and osteoblasts as observed under the electron microscope. These data suggest a new paradigm of local modulation of bone biology by a MØ-derived TSH-like molecule and raise the question of the relative contribution of local vs pituitary-derived TSH in osteoprotection.

Association between helicobacter pylori and open angle glaucoma: current perspective

Helicobacter pylori is a Gram negative, spiral-shaped, strictly micro-aerophilic and flagellate human pathogen that can inhabit many areas of stomach. H. pylori infection leads to the generation of oxygen free radicals. H. pylori infection might also aggravate the course of glaucoma by increasing the levels of nitric oxide, endothelin-1 and free radicals indirectly. This article briefly reviews the current perspectives on this issue.

Transformation of coffee (Coffea Arabica L. cv. Catimor) with the cry1ac gene by biolistic, without the use of markers

The transformation of coffee plantlets with the cry1ac gene of Bacillus thuringiensis was achieved by biolistic using either the whole pUBC plasmid or only the ubi-cry1ac-nos genetic cassette. The cry1ac gene was inserted into coffee plants in order to confer resistance to the leaf miner Leucoptera coffeella, an insect responsible for considerable losses in coffee crops. Bearing in mind that the genetic cassettes used for this study lack reporter genes and/or selection marker genes, the parameters for the transformation procedure by biolistic were previously standardised with a plasmid carrying the gus reporter gene. The presence of the cry1ac gene in young plantlet tissues was determined by PCR, Southern blot and reverse transcription-PCR. Our results show that the obtainment of viable coffee plantlets, transformed by bombardment with the cry1ac gene and without selection markers nor reporter genes, is feasible.

Calcium signalling and calcium transport in bone disease

Calcium transport and calcium signalling mechanisms in bone cells have, in many cases, been discovered by study of diseases with disordered bone metabolism. Calcium matrix deposition is driven primarily by phosphate production, and disorders in bone deposition include abnormalities in membrane phosphate transport such as in chondrocalcinosis, and defects in phosphate-producing enzymes such as in hypophosphatasia. Matrix removal is driven by acidification, which dissolves the mineral. Disorders in calcium removal from bone matrix by osteoclasts cause osteopetrosis. On the other hand, although bone is central to management of extracellular calcium, bone is not a major calcium sensing organ, although calcium sensing proteins are expressed in both osteoblasts and osteoclasts. Intracellular calcium signals are involved in secondary control including cellular motility and survival, but the relationship of these findings to specific diseases is not clear. Intracellular calcium signals may regulate the balance of cell survival versus proliferation or anabolic functional response as part of signalling cascades that integrate the response to primary signals via cell stretch, estrogen, tyrosine kinase, and tumor necrosis factor receptors.

Molecular physiology and pharmacology of calcitonin

Calcitonin is a thirty-two amino acid peptide that contains an N-terminal disulphide bridge and a C-terminal prolineamide residue. It is released from thyroid parafollicular C-cells and its direct actions on the osteoclast account for its physiological effects whether as a hypocalcaemic agent and a potent inhibitor of bone resorption. These effects likely reflect actions upon a number of specific osteoclast cell surface receptors that initiate intracellular signaling events through both cyclic AMP and calcium mediated second messenger pathways. Studies of its potent anti-resorptive effects have significant translational implications in the management of Paget's bone disease, osteoporosis, and hypercalcaemia. This chapter summarizes major concepts in the synthesis and structure of calcitonin and then proceeds to outline its cellular, molecular actions and therapeutic applications, whilst seeking to provide a reference source. More detailed accounts have been given on different aspects of calcitonin physiology and biochemistry in a number of recent reviews by ourselves and others (155,157, Zaidi et al., 1994; 2002).

A profile and spectrum of four cases of methicillin-resistant Staphylococcus aureus in a burns intensive care unit

This report describes and evaluates four patients with hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas infections at the Burns and Plastic Surgery Hospital, in Libya, between August 1999 and August 2002. Neither rifampicin nor vancomycin was used to treat these patients. Inhalation injury with major burns (> 60% total body surface area), a major degree of burns (3rd degree), and septicaemia caused by both MRSA and multi-resistant P. aeruginosa invariably proved fatal. One patient responded well to antibiotic therapy, but the other three died in spite of similar therapy. Vancomycin and rifampicin should be established as the first choice to treat MRSA infection, and infected wounds need aggressive management with antibiotics prior to skin grafting.

Biological properties and mechanism of action of ibandronate: application to the treatment of osteoporosis

Bisphosphonates, with their proven efficacy and safety, are the most commonly prescribed treatment for women with postmenopausal osteoporosis; however, optimal efficacy is often not achieved due to poor patient adherence to medication. Poor adherence leads to an increased risk of fracture, which itself results in morbidity, elevated healthcare costs and potentially, mortality. Although weekly rather than daily dosing of bisphosphonates has improved adherence, there remains a significant problem, and dosing less frequently than weekly has been suggested as a possible means for further improving adherence. Ibandronate is a new bisphosphonate that has a specific structure and set of characteristics that enable less frequent dosing than currently available bisphosphonates. This review provides details of the general structural features of all bisphosphonates and how these are understood to contribute to their functions in osteoporosis treatment. From this, the unique structure of ibandronate is described, along with how this translates into the high antiresorptive potency, favorable bone-binding, persistence in bone, and good tolerability that permits less frequent dosing. Finally, the clinical evidence for ibandronate is briefly presented, demonstrating the viability of less frequent dosing, with its potential benefits for patient convenience and adherence to therapy.

Calcium absorption and bone mineral density in celiacs after long term treatment with gluten-free diet and adequate calcium intake

Calcium malabsorption, hypocalcemia and skeletal demineralization are well-recognized features of untreated celiac disease. This study investigates calcium absorption and bone mineral density (BMD) after a prolonged, over 4 years, treatment with a gluten-free diet. Twenty-four adult females with treated celiac disease and twenty age- and sex-matched control subjects were studied. Mean body mass index (MBI), energy intake, serum calcium, and serum 25(OH)D concentrations in treated celiacs did not differ from controls. However, while both dietary calcium and protein intake were significantly higher in celiacs (P<0.012), fractional calcium absorption was lower (mean percentage+/-SD; treated 39.8+/-12 versus controls 52.3+/-10, P<0.001). Thus, after adjusting for calcium intake, the estimated amount of calcium absorbed daily was similar in both groups. Whole body, spine and trochanter BMD were significantly lower in treated celiac patients compared with controls (P<0.05). There were significant inverse correlations between: serum parathyroid hormone (PTH) and femoral neck or total body BMD (P<0.01), PTH and duration of gluten-free diet (P=0.05), and fractional calcium absorption and alkaline phosphatase (P=0.022). Increased calcium intake could potentially compensate for the reduced fractional calcium absorption in treated adult celiac patients, but may not normalize the BMD. In addition, the inverse correlation between PTH and time following treatment is suggestive of a continuing long-term benefit of gluten withdrawal on bone metabolism in celiac patients.