Phytoplankton Response to Environmental Variables and Organic Pollutants. Laboratory Cultures and Numerical Simulations Experiments

Herbicides are becoming emergent contaminants in Italian surface, coastal and ground waters, due to their intensive use in agriculture. In marine environments herbicides have adverse effects on non-target organisms, as primary producers, resulting in oxygen depletion and decreased primary productivity. Alterations of species composition in algal communities can also occur due to the different sensitivity among the species. In the present thesis the effects of herbicides, widely used in the Northern Adriatic Sea, on different algal species were studied. The main goal of this work was to study the influence of temperature on algal growth in the presence of the triazinic herbicide terbuthylazine (TBA), and the cellular responses adopted to counteract the toxic effects of the pollutant (Chapter 1 and 2). The development of simulation models to be applied in environmental management are needed to organize and track information in a way that would not be possible otherwise and simulate an ecological prospective. The data collected from laboratory experiments were used to simulate algal responses to the TBA exposure at increasing temperature conditions (Chapter 3). Part of the thesis was conducted in foreign countries. The work presented in Chapter 4 was focused on the effect of high light on growth, toxicity and mixotrophy of the ichtyotoxic species Prymnesium parvum. In addition, a mesocosm experiment was conducted in order to study the synergic effect of the pollutant emamectin benzoate with other anthropogenic stressors, such as oil pollution and induced phytoplankton blooms (Chapter 5).

The constitutive activation of the DNA damage response pathway is a novel therapeutic target in aggressive B-cell lymphoma

The recent finding that MYC-driven cancers are sensitive to inhibition of the DNA damage response (DDR) pathway, prompted us to investigate the role of DDR pathway as therapeutic target in diffuse large B-cell lymphoma (DLBCL), which frequently overexpresses the MYC oncogene. In a preliminary immunohistochemical study conducted on 99 consecutive DLBCL patients, we found that about half of DLBCLs showed constitutive expression of the phosphorylated forms of checkpoint kinases (CHK) and CDC25c, markers of DDR activation, and of phosphorylated histone H2AX (γH2AX), marker of DNA damage and genomic instability. Constitutive γH2AX expression correlated with c-MYC levels and DDR activation, and defined a subset of tumors characterised by poor outcome. Next, we used the CHK inhibitor PF-0477736 as a tool to investigate whether the inhibition of the DDR pathway might represent a novel therapeutic approach in DLBCL. Submicromolar concentrations of PF-0477736 hindered proliferation in DLBCL cell lines with activated DDR pathway. These results were fully recapitulated with a different CHK inhibitor (AZD-7762). Inhibition of checkpoint kinases induced rapid DNA damage accumulation and apoptosis in DLBCL cell lines and primary cells. These data suggest that pharmacologic inhibition of DDR through targeting of CHK kinases may represent a novel therapeutic strategy in DLBCL. The second part of this work is the clinical, molecular and functional description of a paradigmatic case of primary refractory Burkitt lymphoma characterized by spatial intratumor heterogeneity for the TP53 mutational status, high expression levels of genomic instability and DDR activation markers, primary resistance to chemotherapy and exquisite sensitivity to DDR inhibitors.

A prospective study on the early evaluation of response to androgen receptor-targeted agents with 11C-Choline, 68Ga-PSMA and 18F-FACBC PET in metastatic castration-resistant prostate cancer: a single center experience.

Background: The early identification of responsive and resistant patients to androgen-receptor targeting agents (ARTA) in metastatic castration resistant-prostate cancer (CRPC) is not completely possible with PSA assessment and conventional imaging. Considering its ability to determine metabolic activity of lesions, PET assessment might be a promising tool. Materials and methods: We performed a monocentric prospective study in patients with metastatic CRPC under treatment with ARTA to evaluate the role of different PET radiotracers: 49 patients were randomized to receive 11C-Choline, 18F-FACBC or 68Ga-PSMA PET, one scan before therapy onset and one two months later. The primary aim was to investigate the performance of three different novel PET radiotracers for the early evaluation of response to ARTA in metastatic CRPC patients; with regards to this aim, the outcome evaluated was biochemical response (PSA reduction ≥50%). The secondary aim was to investigate the prognostic role of several semiquantitative PET parameters and their variations with the different radiotracers in terms of biochemical PFS (bPFS) and overall survival (OS). The study was promoted by the Italian Department of Health (code RF-2016-02364809). Results: With regards to the primary endpoint, at univariate analysis a statistically significant correlation was found between MTV_VARIATION% (p=0.018) and TLA_VARIATION% (p=0.025) with 68Ga-PSMA PET and biochemical response. As for the secondary endpoints, significant correlations with bPFS were found for 68Ga-PSMA PET MTV_TOT_PET1 (p=0.001), TLA_TOT_PET1 (p=0.025), MTV_VARIATION% (p=0.031). For OS, statistically significant correlations were found for: MAJ_SUV_MAX_PET1 with 11C-Choline PET (p=0.007); MTV_TOT_PET1 (p=0.004), MAJ_SUV_MAX_PET1 (p=0.029), SUVMAX_VARIATION% (p=0.04), MTV_VARIATION% (p=0.015), TLA_VARIATION% (p=0.03) with 68Ga-PSMA PET,; MTV_TOT_PET1 (p=0.011), TLA_TOT_PET1 (p=0.009), MAJ_SUV_MAX_PET1 (p=0.027), MTV_VARIATION% (p=0.048) with 18F-FACBC. Conclusions: Our prospective study highlighted that several 68Ga-PSMA and 18F-FACBC semiquantitative PET parameters and their variations present a prognostic value in terms of OS and bPFS and a correlation with biochemical response, that could help to assess response to ARTA.