Investigation of the antiproliferative and anti-invasive effects of perylic alcohol on medulloblastoma-SHH, and its influence on the modulation of RAS and its effectors

Author(s)

Marcela de Oliveira Silva

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2018-10-31

Examining board members

Maria Sol Brassesco Annichini; Leticia Fröhlich Archangelo; Ricardo Santos de Oliveira; Thereza Fonseca Quirico dos Santos

• Advisor: Maria Sol Brassesco Annichini

Abstract

Medulloblastoma (MB) is the most common malignant brain tumor in childhood. It is currently classified not only by prognostic and histological factors but also by deregulated molecular pathways into WNT (Wingless), SHH (Sonic Hedgehog), Group 3 and Group 4. The standard treatment consists of resection followed by local and craniospinal radiotherapy, and adjuvant chemotherapy. The knowledge of the molecular alterations has been important for the improvement of therapeutic strategies. The SHH subgroup presents variants considered resistant to chemotherapy, due to the activation of the RAS-MAPK pathway. Perillyl Alcohol (POH), a monoterpene found in small concentrations in different plants, has shown favorable effects for the treatment of several tumor types. However, the exact mechanisms of action of this compound remain uncertain. It is believed that POH precludes the post-translational modification of RAS protein by inhibiting the activity of the enzyme farnesyltransferase and / or geranylgeranyl transferase. Recently, the intranasal administration of POH has been seen as a non-invasive and direct blood-brain barrier delivery option for the treatment of Central Nervous System (CNS) tumors. Previous in vitro studies performed by our group showed that POH decreased cell proliferation and colony formation, with increased cell death in pediatric MB strains. Thus, in the present study we studied the in vitro effects of POH in relation to cell invasion and the modulation of RAS and its effectors in pediatric MB cell lines as well as its antiproliferative effects in vivo. Our results showed that POH does not affect the cellular location of small GTPases, RAS, RHOA and RHOC, nor does it significantly alter the activation of ERK in the cell lines studied. The invasive and migratory capacity after treatment varied according to the cell line and the assay performed. Regarding the in vivo effects in mice with subcutaneous tumors treated by intraperitoneal injections of POH, we can observe a reduction in tumor volume and a slight decrease in phosphorylated ERK, although there is a greater proliferation marking (Ki-67) in the treated tumor cells. Conversely, in animals with intracranial tumors submitted to intranasal administration of the drug, there was no reduction in tumor volume after treatment compared to control, or when combined with radiotherapy, and Ki-67 immunostaining showed no difference between groups. POH was not cytotoxic to the nasal cavity of animals submitted to inhalation. Using gas chromatography coupled to mass spectrometry (GC-MS) it was not possible to detect POH in samples from CNS, plasma and lung from mice treated intranasally. Thus, although clinical studies conducted with inhaled POH in CNS tumors have shown favorable results, from the data presented herein we can infer that the use of POH in MB-SHH may not be effective in reducing tumor volume. Moreover, at least in this tumor, the form of action of this drug does not affect the pathway of signaling and cellular localization of RAS. (AU)

• FAPESP's process: 16/08125-5 - Investigation of anti-proliferative and anti-invasive effects of perillyl alcohol on medulloblastoma-SHH and its influence on the modulation Ras and its effectors
• Grantee: Marcela de Oliveira Silva
• Support Opportunities: Scholarships in Brazil - Master