Ion channels in the pathophysiology and therapeutics of brain tumors

Transcription

1 Workshop dipartimentale 2 dicembre 2015 Gruppo di ricerca Fisiopatologia Cellulare e Molecolare Main research Ion channels in the pathophysiology and therapeutics of brain tumors Components: Fabio Franciolini, coordinator - Luigi Catacuzzeno - Valeria Marsili - Marita Rita Micheli - Bernard Fioretti - Silvia Belia - Rodolfo Bova - Luigi Sforna - Martino Caramia - Marta Cenciarini - Claudia Tubaro

2 Ion channels of cell membranes

3 Recording ion currents from membrane channels

4 Human glioblastoma, the most lethal brain tumor Nuclear magnetic resonance image of a glioblastoma Survival curves of glioblastoma patients as function of various treatments Glioblastoma are the most lethal primary brain tumors, but their prognosis has changed little over the past 30 years, despite comprehensive and intensive treatment. Average survival is just over a year from diagnosis. Emerging fields of investigation attempt at understanding the pathophysiologic response to hypoxia and to develop novel nanomedicine approaches for new therapies. In both fields ion channels play major roles.

5 Main research lines of the group Hypoxia and Cl - channel modulation in human glioblastoma cells: impact on cell survival [Catacuzzeno, Sforna, Belia, Cenciarini, Franciolini] Nanomedicine in human glioblastoma [Fioretti, Franciolini] Megalencephalic leukoencephalopathy and Cl - channels [Catacuzzeno, Caramia, Franciolini]

6 Hypoxia and Cl - channel modulation in human glioblastoma cells: impact on cell survival Histopathologic features of pseudopalisades in glioblastoma. The presence of hypoxic areas strongly correlates with the malignancy of glioblastoma, but the underlying mechanisms are still unclear. Hypoxia adversely affects the sensitivity of tumors to radiation therapy, increases mutation frequency, alters expression of genes involved in cell cycle regulation, and impacts treatment outcome and patient survival. Glioblastoma cells express abundant Cl - channels, whose activity mainly supports cell volume changes, needed for cell proliferation, migration, and death evasion. We verified whether hypoxia modulates Cl - channels in glioblastoma, and whether this increases aggressiveness.

7 Chloride channels underlie cell volume regulation

8 Acute application of hypoxic solution activates a Cl - current (ICl hypoxia ) in GBM cell lines

9 Hypoxia-activated chloride current has the biophysical and pharmacological properties of the swelling-activated chloride current INSTANTANEOUS ACTIVATION - - TIME AND VOLTAGE DEPENDENT INACTIVATION - DIDS: VOLTAGE DEPENDENT BLOCK - NPPB: VOLTAGE INDEPENDENT BLOCK

10 Acute hypoxia increase cellular volume Volume increase is necessary for ICl hypoxia activation

11 Hypoxia induces regulatory volume decrease (RVD) in GBM cells by ICl hypoxia activation

12 Activation of ICl hypoxia current preserves U87 glioblastoma cells from necrotic death after hypoxic insult

13 CONCLUSIONS In GBM cells, acute hypoxia induces cellular swelling and subsequent activation of volume-activated Cl - current The activation of ICl hypoxia underlies RVD and preserves GBM cells from hypoxia-induced necrotic death

14 Research line Nanomedicine in human glioblastoma [Fioretti, PI Progetto SIR 2015, Franciolini]

15 Nanoparticles and glioblastoma - Glioblastoma gold standard therapy The gold standard therapy, the Stupp protocol The standard of care is surgical resection followed by externalbeam radiation therapy (60 Gy in fractions) and adjuvant temozolomide 75 mg/m 2 /day PO on days 1-42, usually 1-1.5h before radiation

16 Nanoparticles and glioblastoma - Ionizing radiations and nanoparticles on cell cycle Cell survival (100%) Ionizing Radiation (IR) Silver NanoParticles (AgNPs) Reactive Oxygen Species (ROS) DNA damage Cyclin inhibition Metabolism drop G2/M phase accumulation AgNPs increase IR-induced cell death AgNPs and IR accumulate glioblastoma cells in G2/M. Cl - channel blockers partially contrast this accumulation AgNPs- and IR-induced cell accumulation in G2/M favors cell death Cell repair Cell death

17 Nanoparticles and glioblastoma - Silver nanoparticles and Cl - currents Basic physical-chemical properties of AgNPs to be used in the study AgNPs activate Cl- currents and depolarize resting membrane potential.

18 Nanoparticles and glioblastoma - Cl - currents on cell volume regulation Cl - current activation Cl - currents regulate cell volume changes in several biological processes, from RVD, AVD and PMC Cell volume regulation Regulatory Volume Decrease (RVD) Apoptotic Volume Decrease (AVD) Pre-Mitotic Condensation (PMC)

19 Nanoparticles and glioblastoma - CAM/glioblastoma model Biocompatibility test of various AgNPs formulation obtained by using chick embryo in vivo model GBM at E12 H&E (CAM/GBM) E12 Intravital microscopy Advantages of the CAM model: Quick tumor mass formation Histologic features of GBM Wide range of treatment Cheaper than intracranially xenotransplanted mice model Ideal for optimization of protocols Evaluated parameters: Toxicity Biodistribution Dosage Effects on the tumor growth Effects on the cell migration Angiogenesis Invasion

20 Napoparticles and glioblastoma - Intracranial xenotransplanted mouse model Xenograft Drugs Radiotherapy + + Evaluated parameters: Biodistribution and accumulation Tumor mass Infiltration/invasion Survival curves

21 Nanoparticles and glioblastoma - Brain cancer targeting Synthesis of lipophilic AgNPs (LAgNPs) Synthesis of lipophilic AgNPs chlorotoxin-modified liposome (LAgNPs- CML) Chlorotoxin is presently the only approved agent for brain tumor targeting. It recognizes metalloproteases specific of brain tumors. Liposomes diameter, mm.

22 Research line Megalencephalic leukoencephalopathy and ion channels [Catacuzzeno, Caramia, Franciolini]

23 MEGALENCEPHALIC LEUKOENCEPHALOPATHY MLC is a rare inherited, autosomal recessive form of childhood-onset spongiform leukodistrophy Macrocephaly Deterioration of motor functions Epileptic seizures Mental decline Brain edema Subcortical cysts Myelin and astrocytes vacuolation Child with megalencephalic leukoencephalopathy MRI scans in MLC [from Van der Knapp et al., 2012]

24 MLC1 PROTEIN: THE MAIN ACTOR IN MLC DESEASE MLC1 protein is mainly expressed in brain astrocytes, specifically in astrocytic end-feet contacting perivascular blood vessels, and is mutated in about 80% of MLC patients. The role of MLC1 protein in brain physiology is still under debate. Scheme of MLC1 interactions in perivascular astrocytes. MLC1 may controll the flow of fluids into the cell [from Brignone et al., 2015]. MLC1 modulates several signal transduction pathways including ERK and PLCg pathways

25 MLC1 PROTEIN MODULATES ION CHANNELS MLC1 upregulates IClswell current in Xenopus oocytes handly defolliculated MLC1 upregulates IClswell current in U251 astrocytoma cells MLC1 reduces KCa3.1 current density in U251 astrocytoma cells