Preclinical Studies with Glioblastoma Brain Organoid Co-Cultures Show Efficient 5-ALA Photodynamic Therapy

BACKGROUND

The high recurrence of glioblastoma (GB) that occurs adjacent to the resection cavity within two years of diagnosis urges an improvement of therapies oriented to GB local control. Photodynamic therapy (PDT) has been proposed to cleanse infiltrating tumor cells from parenchyma to ameliorate short long-term progression-free survival. We examined 5-aminolevulinic acid (5-ALA)-mediated PDT effects as therapeutical treatment and determined optimal conditions for PDT efficacy without causing phototoxic injury to the normal brain tissue.

METHODS

We used a platform of Glioma Initiation Cells (GICs) infiltrating cerebral organoids with two different glioblastoma cells, GIC7 and PG88. We measured GICs-5-ALA uptake and PDT/5-ALA activity in dose-response curves and the efficacy of the treatment by measuring proliferative activity and apoptosis.

RESULTS

5-ALA (50 and 100 µg/mL) was applied, and the release of protoporphyrin IX (PpIX) fluorescence measures demonstrated that the emission of PpIX increases progressively until its stabilization at 24 h. Moreover, decreased proliferation and increased apoptosis corroborated the effect of 5-ALA/PDT on cancer cells without altering normal cells.

CONCLUSIONS

We provide evidence about the effectiveness of PDT to treat high proliferative GB cells in a complex in vitro system, which combines normal and cancer cells and is a useful tool to standardize new strategic therapies.

Abstract 368: Improving glioblastoma treatment specificity and efficacy of mApoE-targeted liposome by MMP2-controlled drug releasee

Recent evidence from our laboratory provided proof-of-concept for therapeutic potential for glioblastoma (GBM) of a combination strategy based on radiation and adjuvant doxorubicin-loaded liposomes (LIPs) conjugated with a modified Apolipoprotein E-derived peptide (mApoE), known to facilitate Blood Brain Barrier (BBB)-crossing. Significant glioma stem cell (GSC) apoptosis, tumor growth inhibition and increased overall survival were observed in vivo upon combined treatment offering attractive and innovative therapeutic possibilities for GBM. To strengthen therapeutic efficacy and lower off-target effects, we implemented mApoE-LIPs with a matrix metalloproteinases (MMP)-activable element that allows controlled payload release only in the MMPs rich tumor microenvironment, thus concurring to reduce unspecific interaction in healthy tissue where MMPs are low or absent Given the MMP2 overexpression in GBM, a MMP2-activable block (M2AB) was included in the phospholipid bilayer of mApoE-LIPs. The M2AB efficacy was evaluated on patient-derived GSCs displaying different MMP2 enzymatic activities by means of calcein-loaded M2AB/mApoE-LIPs. Human endothelial cells (hCMEC/d3), not expressing MMP2, were included to validate the targeted strategy as well as to assay the cytotoxicity on non-tumoral cells. Intracellular calcein quantification showed that: 1) calcein uptake correlates with MMP2 activity level; 2) M2AB/mApoE functionalization augmented calcein internalization into GSCs compared to mApoE alone. The MEK/ERK pathway, known to supports GBM cell survival, migration, and radio-resistance was considered as target strategy against GBM. A survey of the MEK/ERK inhibitors Trametinib (TRAM) and Pimasertib (PIMA) in several GSC lines indicated significant induction of GSC apoptosis associated to reduction of ERK phosphorylation. TRAM and PIMA were then encapsulated into mApoE-LIPs and their anti-GSC activity was investigated. Indeed, a dose dependent inhibition of GSC survival and induction of apoptosis combined to a significant lower level of phospho-ERK was observed upon 72h treatment. In conclusion, M2AB/mApoE-LIPs demonstrate: 1) a MMP2-dependent payload release; 2) stability when MMP2 lacks in the cellular milieu; 3) a synergic effect of the double M2AB/mApoE functionalization. TRAM and PIMA encapsulation into LIPs does not alter their anti-GSC activity. Funding by FRRB grant NEVERMIND (CP2_16/2018)

Citation Format: Milena Mattioli, Marco Pizzocri, Elisabetta Stanzani, Valentino Ribecco, Simone Olei, Maria Pia Tropeano, Sabrina Giofrè, Antonio Renda, Sara Pellegrino, Pierfausto Seneci, Francesca Re, Federico Pessina, Michela Matteoli, Lorena Passoni. Improving glioblastoma treatment specificity and efficacy of mApoE-targeted liposome by MMP2-controlled drug releasee [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 368.

Synchrotron-Based Fourier-Transform Infrared Micro-Spectroscopy (SR-FTIRM) Fingerprint of the Small Anionic Molecule Cobaltabis(dicarbollide) Uptake in Glioma Stem Cells

The anionic cobaltabis (dicarbollide) [3,3'-Co(1,2-C2B9H11)2]-, [o-COSAN]-, is the most studied icosahedral metallacarborane. The sodium salts of [o-COSAN]- could be an ideal candidate for the anti-cancer treatment Boron Neutron Capture Therapy (BNCT) as it possesses the ability to readily cross biological membranes thereby producing cell cycle arrest in cancer cells. BNCT is a cancer therapy based on the potential of 10B atoms to produce α particles that cross tissues in which the 10B is accumulated without damaging the surrounding healthy tissues, after being irradiated with low energy thermal neutrons. Since Na[o-COSAN] displays a strong and characteristic ν(B-H) frequency in the infrared range 2.600-2.500 cm-1, we studied the uptake of Na[o-COSAN] followed by its interaction with biomolecules and its cellular biodistribution in two different glioma initiating cells (GICs), mesenchymal and proneural respectively, by using Synchrotron Radiation-Fourier Transform Infrared (FTIR) micro-spectroscopy (SR-FTIRM) facilities at the MIRAS Beamline of ALBA synchrotron light source. The spectroscopic data analysis from the bands in the regions of DNA, proteins, and lipids permitted to suggest that after its cellular uptake, Na[o-COSAN] strongly interacts with DNA strings, modifies proteins secondary structure and also leads to lipid saturation. The mapping suggests the nuclear localization of [o-COSAN]-, which according to reported Monte Carlo simulations may result in a more efficient cell-killing effect compared to that in a uniform distribution within the entire cell. In conclusion, we show pieces of evidence that at low doses, [o-COSAN]- translocates GIC cells' membranes and it alters the physiology of the cells, suggesting that Na[o-COSAN] is a promising agent to BNCT for glioblastoma cells.

P04.03 Different role of integrin a6 in glioblastoma proneural and mesenchymal stem-like cells

BACKGROUND

The plasticity of tumoral cells and the presence of cells displaying stem-like features are two interrelated traits of Glioblastoma (GBM) lesions and both concur in defining its heterogeneity. Particularly, GBM stem-like cells (GSC) can be classified according to trascriptional data in different subgroups, being the Proneural (PN-GSC) and the Mesenchymal (MES-GSC) the most consolidated clusters. GSC are responsible of most of the malignant characteristics of GBM, including therapeutic resistance and tumor recurrence. Therefore, a better understanding of the mechanisms regulating GSC responsiveness to therapy taking into account GSC molecular heterogeneity may help to improve patient’s outcome. Integrin a6 is a commonly used marker for GSC capable to enrich for GSC population and sustain stemness. We investigate the role of integrin a6 in both PN and MES GSC on stemness and radioresistance.

MATERIAL AND METHODS

The expression of integrin a6 was analyzed in GSC cultures obtained from post-surgical specimens either displaying PN or MES trascriptional traits. Using cell sorting to enrich for integrin a6 expression (integrin a6-high and a6-low) and gene silencing with lentiviral-based shRNA, integrin a6 impact on both GSC cultures was tested. Also, silenced MES-GSC were analysed by means of RNA-seq. The major pathways found altered by integrin a6 silencing were validated at functional level using gliomasphere-based clonogenic assay, extreme limiting dilution assay and gamma-H2AX to monitor DNA damage repair kinetics.

RESULTS

After sorting GSC cultures by integrin a6 expression, PN-GSC a6-low showed a significant reduction in clonogenic capability and gliomasphere size when compared to a6-high (p<0.0001). On the contrary, sorted MES-GSC did not display any differences. Similar results were obtained following integrin a6 lentiviral silencing. However, RNAseq on silenced MES-GSC revealed a significant impact on cell cycle regulation and DNA damage repair pathways. Indeed, Integrin a6 trascriptional inhibition in MES-GSCs impaired the capacity to clear gamma-H2AX foci after ionizing radiation (p<0.001) and significantly alters MES-GSC capacity to recover from radiation treatment in gliomasphere formation assay (p<0.01). According to the interpretation of the curves with the linear quadratic model, integrin a6 silenced cells displayed higher alpha- and beta- values and lower alpha/beta ratio. The obtained values demonstrate increased radiosensitivity and impaired capacity to repair sublethal DNA damage, in addition to an enhanced sensitivity to fractionated doses.

CONCLUSION

The data obtained showed that Integrin a6 regulates proliferation and stemness-related features in PN-GSC while supports radioresistance of MES-GSCs. Altogether, we reveal that integrin a6 controls different stem-associated features in GSCs depending on the molecular subtype.

Dual Role of Integrin Alpha-6 in Glioblastoma: Supporting Stemness in Proneural Stem-Like Cells While Inducing Radioresistance in Mesenchymal Stem-Like Cells

Simple Summary

Glioblastoma stem-like cells (GSCs) are responsible for most of the malignant characteristics of glioblastoma, including therapeutic resistance, tumour recurrence, and tumour cellular heterogeneity. Therefore, increased understanding of the mechanisms regulating GSCs aggressiveness may help to improve patients’ outcomes. Here, we investigated the role of integrin a6 in controlling stemness and resistance to radiotherapy across proneural and mesenchymal molecular subtypes. We observed that integrin a6 had a clear role in stemness maintenance in proneural but not in mesenchymal GSCs. In addition, we proved a crucial role of integrin a6 in supporting mesenchymal GSCs resistance to ionizing radiation. Finally, we highlighted that integrin a6 may control different stem-associated features in GSCs, depending on the molecular subtype. The inhibition of integrin a6 limits stem-like malignant characteristics in both GSCs subtypes and thus may potentially control tumour relapse following conventional treatment.

Abstract

Therapeutic resistance after multimodal therapy is the most relevant cause of glioblastoma (GBM) recurrence. Extensive cellular heterogeneity, mainly driven by the presence of GBM stem-like cells (GSCs), strongly correlates with patients’ prognosis and limited response to therapies. Defining the mechanisms that drive stemness and control responsiveness to therapy in a GSC-specific manner is therefore essential. Here we investigated the role of integrin a6 (ITGA6) in controlling stemness and resistance to radiotherapy in proneural and mesenchymal GSCs subtypes. Using cell sorting, gene silencing, RNA-Seq, and in vitro assays, we verified that ITGA6 expression seems crucial for proliferation and stemness of proneural GSCs, while it appears not to be relevant in mesenchymal GSCs under basal conditions. However, when challenged with a fractionated protocol of radiation therapy, comparable to that used in the clinical setting, mesenchymal GSCs were dependent on integrin a6 for survival. Specifically, GSCs with reduced levels of ITGA6 displayed a clear reduction of DNA damage response and perturbation of cell cycle pathways. These data indicate that ITGA6 inhibition is able to overcome the radioresistance of mesenchymal GSCs, while it reduces proliferation and stemness in proneural GSCs. Therefore, integrin a6 controls crucial characteristics across GBM subtypes in GBM heterogeneous biology and thus may represent a promising target to improve patient outcomes.

Radiation and adjuvant drug-loaded liposomes target glioblastoma stem cells and trigger in-situ immune response

Background

The radio- and chemo-resistance of glioblastoma stem-like cells (GSCs), together with their innate tumor-initiating aptitude, make this cell population a crucial target for effective therapies. However, targeting GSCs is hardly difficult and complex, due to the presence of the blood-brain barrier (BBB) and the infiltrative nature of GSCs arousing their dispersion within the brain parenchyma.

Methods

Liposomes (LIPs), surface-decorated with an Apolipoprotein E-modified peptide (mApoE) to enable BBB crossing, were loaded with doxorubicin (DOXO), as paradigm of cytotoxic drug triggering immunogenic cell death (ICD). Patient-derived xenografts (PDXs) obtained by GSC intracranial injection were treated with mApoE-DOXO-LIPs alone or concomitantly with radiation.

Results

Our results indicated that mApoE, through the engagement of the low-density lipoprotein receptor (LDLR), promotes mApoE-DOXO-LIPs transcytosis across the BBB and confers target specificity towards GSCs. Irradiation enhanced LDLR expression on both BBB and GSCs, thus further promoting LIP diffusion and specificity. When administered in combination with radiations, mApoE-DOXO-LIPs caused a significant reduction of in vivo tumor growth due to GSC apoptosis. GSC apoptosis prompted microglia/macrophage phagocytic activity, together with the activation of the antigen-presenting machinery crucially required for anti-tumor adaptive immune response.

Conclusions

Our results advocate for radiotherapy and adjuvant administration of drug-loaded, mApoE-targeted nanovectors as an effective strategy to deliver cytotoxic molecules to GSCs at the surgical tumor margins, the forefront of glioblastoma (GBM) recurrence, circumventing BBB hurdles. DOXO encapsulation proved in situ immune response activation within GBM microenvironment.

Radioresistance of mesenchymal glioblastoma initiating cells correlates with patient outcome and is associated with activation of inflammatory program

Glioblastoma (GBM) still remains an incurable disease being radiotherapy (RT) the mainstay treatment. Glioblastoma intra-tumoral heterogeneity and Glioblastoma-Initiating Cells (GICs) challenge the design of effective therapies. We investigated GICs and non-GICs response to RT in a paired in-vitro model and addressed molecular programs activated in GICs after RT. Established GICs heterogeneously expressed several GICs markers and displayed a mesenchymal signature. Upon fractionated RT, GICs reported higher radioresistance compared to non-GICs and showed lower α- and β-values, according to the Linear Quadratic Model interpretation of the survival curves. Moreover, a significant correlation was observed between GICs radiosensitivity and patient disease-free survival. Transcriptome analysis of GICs after acquisition of a radioresistant phenotype reported significant activation of Proneural-to-Mesenchymal transition (PMT) and pro-inflammatory pathways, being STAT3 and IL6 the major players. Our findings support a leading role of mesenchymal GICs in defining patient response to RT and provide the grounds for targeted therapies based on the blockade of inflammatory pathways to overcome GBM radioresistance.

YM155 sensitizes ovarian cancer cells to cisplatin inducing apoptosis and tumor regression

OBJECTIVE

The objective of this study is to chemosensitize ovarian cancer (OVCa) cells to cisplatin (CDDP) using an inhibitor of Survivin, YM155. The efficacy of YM155 in combination with CDDP was determined in vitro, ex vivo and in vivo.

METHODS

Human OVCa cell lines A2780p and their cisplatin-resistant derivative A2780cis, were treated with CDDP, YM155, and the combined treatment (YM155+CDDP), and cell viability, mRNA and protein expression levels, cell-cycle distribution, and DNA damage were then evaluated. Furthermore, the efficacy of YM155 combined with CDDP was further examined in established primary cell cultures and xenograft models.

RESULTS

The combination of YM155 with CDDP induced G2/M cell cycle arrest and apoptosis, increased DNA damage, and decreased Survivin levels, especially in A2780cis CDDP-resistant cells. Additionally, YM155 in combination with CDDP sensitized primary cell cultures to CDDP. Studies in vivo showed how this combination significantly decreased the tumor size of OVCa xenografts.

CONCLUSIONS

Our results demonstrate that in OVCa cells the expression of Survivin did not affect their sensitivity to YM155, suggesting that Survivin was not the only target of YM155. The combination of YM155 with CDDP could be a good option for therapy of CDDP-resistant OVCa, independently of p53 status.