Race influences survival in glioblastoma patients with KPS ≥ 80 and associates with genetic markers of retinoic acid metabolism

CRYβB2 alters cell adhesion to promote invasion in a triple-negative breast cancer cell line

OBJECTIVE

African American women with breast cancer experience disproportionately poor survival outcomes, primarily due to the high prevalence of the deadliest subtype; triple-negative breast cancer (TNBC). The CRYβB2 gene is upregulated in tumors from African American patients across all breast cancer subtypes, including TNBC, and is associated with worse survival rates. This study investigated the effect of CRYβB2 on the invasion of TNBC cells and the underlying mechanisms contributing to this phenotype.

RESULTS

We utilized the SUM159 cells with stable CRYβB2 overexpression in a 3D-culture tumor spheroids model in our investigation. A quantitative 3D invasion assay demonstrated that CRYβB2 overexpression significantly enhanced invasion (median invasion %; SUM159 = 0.14 and SUM159 + CRYβB2 = 0.33). RNA sequencing analysis indicated that CRYβB2 overexpression modulated cell-cell adhesion and extracellular matrix organization pathways, which are critical to invasion of cancer cells. Specifically, CRYβB2 suppressed the expression of key cell-cell adhesion genes known as clustered protocadherins and promoted the expression of PCDH7, a nonclustered protocadherin with known oncogenic roles in various cancers. Notably, the knockout of PCDH7 diminished the invasive capacity induced by CRYβB2 (median invasion %; SUM159 = 0.093, SUM159 + CRYβB2 = 0.184 and SUM159 + CRYβB2/PCDH7-/-=0.082). These findings provide a novel link between a previously identified differentially expressed gene, CRYβB2, in driving breast cancer phenotypes by modulating a class of adhesion proteins.

Crystallin β-b2 promotes retinal ganglion cell protection in experimental autoimmune uveoretinitis

Crystallin βb2 (crybb2) is upregulated in regenerating retinas and in various pathological conditions of the retina, including uveoretinitis. However, the role of crybb2 in this disease is largely unknown. Therefore, we used recombinant crybb2 (rcrybb2) as intravitreal treatment of B10.RIII mice prior to immunization with human interphotoreceptor retinoid-binding protein peptide 161-180 (hIRBPp161-180) in complete Freund's adjuvant (CFA) and concomitant injection of pertussis toxin (PTX) to induce experimental autoimmune uveoretinitis (EAU). In naïve mice, more beta III-tubulin (TUBB3) + and RNA-binding protein with multiple splicing (RBPMS) + cells were found in the ganglion cell layer of the retina than in EAU eyes, suggesting a loss of retinal ganglion cells (RGC) during the development of EAU. At the same time, the number of glial fibrillary acidic protein (GFAP) + cells increased in EAU eyes. RGCs were better protected in EAU eyes treated with rcrybb2, while the number of GFAP+ cells decreased. However, in retinal flatmounts, both retinal ganglion cells and retinal endothelial cells stained positive for TUBB3, indicating that TUBB3 is present in naïve B10.RIII mouse eyes not exclusive to RGCs. A significant decline in the number of RBPMS-positive retinal ganglion cells was observed in retinal flatmounts from EAU retinas in comparison to naïve retinas or EAU retinas with intravitreal rcrybb2 treatment. Whereas no significant decrease in TUBB3 levels was detected using Western blot and RT-qPCR, GFAP level, as a marker for astrocytes, increased in EAU mice compared to naïve mice. Level of Bax and Bcl2 in the retina was altered by treatment, suggesting better cell survival and inhibition of apoptosis. Furthermore, our histologic observations of the eyes showed no change in the incidence and severity of EAU, nor was the immune response affected by intravitreal rcrybb2 treatment. Taken together, these results suggest that intravitreal injection of rcrybb2 reduces retinal RGC death during the course of EAU, independent of local or systemic autoimmune responses. In the future, treating posterior uveitis with rcrybb2 to protect RGCs may offer a promising novel therapeutic strategy.

Racial Disparities in Glioblastoma Genomic Alterations: A Comprehensive Analysis of a Multi-Institution Cohort of 2390 Patients

BACKGROUND

Although molecular biomarkers have significantly advanced precision oncology in glioblastoma, the prevalence of these biomarkers by race remains underexplored. This study aims to characterize the genomic alterations in glioblastoma across Asian, Black, and White patients, offering insights into racial disparities that may influence treatment outcomes and disease progression.

METHODS

Analyzing data from the American Association for Cancer Research Project Genomics Evidence Neoplasia Information Exchange database V13.0, this study examined 2390 primary glioblastoma samples from unique patients. Genomic alterations in 566 cancer-related genes were assessed using targeted next-generation sequencing panels from 3 large cancer institutes. The patient cohort included 112 Asians, 67 Blacks, and 2211 Whites. Statistical significance of associations between genomic alterations and race was evaluated using the chi-squared test, with the Benjamini-Hochberg method applied to control for multiple testing adjustments.

RESULTS

Significant racial differences were observed in the frequency of genomic alterations. Asians exhibited a higher frequency of TP53 alterations (52.68%, P < 0.001), Blacks showed more frequent alterations in NRAS (7.46%, P < 0.001), MTOR (10.45%, P = 0.039), and TET2 (8.96%, P = 0.039), and Whites had a higher occurrence of PTEN alterations (48.67%, P = 0.045). Additionally, Black patients had an elevated rate of RET deletions (14.29%, P < 0.001).

CONCLUSIONS

This study identifies significant racial disparities in the alteration frequencies of 6 key glioblastoma genes: NRAS, TP53, MTOR, TET2, PTEN, and RET. These findings underscore the need for racial considerations in glioblastoma treatment strategies and highlight potential avenues for targeted therapeutic interventions. Further research is needed to explore the clinical implications of these genomic disparities.

A New Vista of Aldehyde Dehydrogenase 1A3 (ALDH1A3): New Specific Inhibitors and Activity-Based Probes Targeting ALDH1A3 Dependent Pathways in Glioblastoma, Mesothelioma and Other Cancers

Aldehyde dehydrogenases of the subfamily 1A (ALDH1A) are enzymes necessary for the oxidation of all-trans or 9-cis retinal to retinoic acid (RA). Retinoic acid and its derivatives are important for normal development and maintenance of epithelia, reproduction, memory, and immune function in adults. Moreover, in recent years, it has been demonstrated that ALDH1A members are also expressed and functional in several human cancers where their role is not limited to the synthesis of RA. Here, we review the current knowledge about ALDH1A3, one of the 1A isoforms, in cancers with an emphasis on two of the deadliest tumors that affect humans: glioblastoma multiforme and mesothelioma. In both tumors, ALDH1A3 is considered a negative prognostic factor, and its level correlates with excessive proliferation, chemoresistance, and invasiveness. We also review the recent attempts to develop both ALDH1A3-selective inhibitors for cancer therapy and ALDH1A3-specific fluorescent substrates for fluorescence-guided tumor resection.

Disparities in Neuro-Oncology

PURPOSEOF REVIEW

Health disparities are preventable differences in the diagnosis, treatment, and outcomes of many diseases, including central nervous system (CNS) tumors. This review will summarize and compile the existing literature on health disparities in neuro-oncology and provide directions for future research and interventions.

RECENT FINDINGS

Patients from historically marginalized groups are more likely to receive inadequate treatment, develop complications, and experience a shorter life expectancy. Financial toxicity can be particularly severe for patients with CNS tumors due to the high costs of treatment. Additionally, CNS clinical trials and research lack diverse representation.

RAR-Dependent and RAR-Independent RXR Signaling in Stem-like Glioma Cells

Retinoic acid (RA) exerts pleiotropic effects during neural development and regulates homeostasis in the adult human brain. The RA signal may be transduced through RXR (retinoid-X receptor)-non-permissive RA receptor/RXR heterodimers or through RXR-permissive RXR heterodimers. The significance of RA signaling in malignant brain tumors such as glioblastoma multiforme (GBM) and gliosarcoma (GS) is poorly understood. In particular, the impact RA has on the proliferation, survival, differentiation, or metabolism of GBM- or GS-derived cells with features of stem cells (SLGCs) remains elusive. In the present manuscript, six GBM- and two GS-derived SLGC lines were analyzed for their responsiveness to RAR- and RXR-selective agonists. Inhibition of proliferation and initiation of differentiation were achieved with a RAR-selective pan-agonist in a subgroup of SLGC lines, whereas RXR-selective pan-agonists (rexinoids) supported proliferation in most SLGC lines. To decipher the RAR-dependent and RAR-independent effects of RXR, the genes encoding the RAR or RXR isotypes were functionally inactivated by CRISPR/Cas9-mediated editing in an IDH1-/p53-positive SLGC line with good responsiveness to RA. Stemness, differentiation capacity, and growth behavior were preserved after editing. Taken together, this manuscript provides evidence about the positive impact of RAR-independent RXR signaling on proliferation, survival, and tumor metabolism in SLGCs.

Molecular and clinicopathological implications of PRAME expression in adult glioma

BACKGROUND

PRAME (PReferentially expressed Antigen in MElanoma) is a biomarker studied in various human cancers. Little is known about the biological implications of PRAME in glioma. We aimed to perform a comprehensive analysis to explore PRAME gene expression and its biological and clinicopathological significance in gliomas.

METHODS AND MATERIALS

We accessed the human cancer atlas (TCGA) database to collect glioma patients (n = 668) with primary tumors and gene expression data. Single nucleotide variants, copy number variation, DNA methylation data, and other clinicopathological factors were also extracted for the analysis.

RESULTS

Overall, 170, 484, and 14 tumors showed no expression, low expression (FPKM≤1), and overexpression (FPKM>1) of the PRAME gene, respectively. The principal component analysis and pathway analyses showed that PRAME-positive gliomas (n = 498), which consisted of tumors with PRAME low expression and overexpression, expressed different oncogenic profiles, possessing higher activity of Hedgehog, P3IK-AKT-mTOR, and Wnt/β-catenin pathways (p<0.001). DNA methylation analysis also illustrated that PRAME-positive tumors were distributed more densely within a grade 4-related cluster (p<0.001). PRAME positivity was an independent prognostic factor for poor outcomes in a multivariate cox analysis adjusted for clinical characteristics and genetic events. Kaplan-Meier analysis stratified by revised classification showed that PRAME positivity was solely associated with IDH-wildtype glioblastoma, grade 4. Finally, PRAME-overexpressing cases (n = 14) had the worst clinical outcome compared to the PRAME-negative and PRAME-low cohorts (adjusted p<0.001) in pairwise comparisons.

CONCLUSION

PRAME expression statuses may dictate different biological and clinicopathological profiles in IDH-wildtype glioblastoma.

Racial and ethnic disparities in brain tumour survival by age group and tumour type

PURPOSE

The extent to which racial/ethnic brain tumour survival disparities vary by age is not very clear. In this study, we assess racial/ethnic brain tumour survival disparities overall by age group and type.

METHODS

Data were obtained from the Surveillance, Epidemiology, and End Results (SEER) 18 registries for US-based individuals diagnosed with a first primary malignant tumour from 2007 through 2016. Cox proportional hazards regression was used to compute adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the association between race/ethnicity and brain tumour survival, stratified by age group and tumour type.

RESULTS

After adjusting for sex, socioeconomic status, insurance status, and tumour type, non-Hispanic (NH) Blacks (HR: 1.26; 95% CI: 1.02-1.55), NH Asian or Pacific Islanders (HR: 1.29; 95% CI: 1.01-1.66), and Hispanics (any race) (HR: 1.28; 95% CI: 1.09-1.51) all showed a survival disadvantage compared with NH Whites for the youngest age group studied (0-9 years). Furthermore, NH Blacks (HR: 0.88; 95% CI: 0.91-0.97), NH Asian or Pacific Islanders (HR: 0.84; 95% CI: 0.77-0.92), and Hispanics (any race) (HR: 0.91; 95% CI: 0.85-0.97) all showed a survival advantage compared with NH Whites for the 60-79 age group. Tests for interactions showed significant trends, indicating that racial/ethnic survival disparities disappear and even reverse for older age groups (P < 0.001). This reversal appears to be driven by poor glioblastoma survival among NH Whites (P < 0.001).

CONCLUSION

Disparities in brain tumour survival among minorities exist primarily among children and adolescents. NH White adults show worse survival than their minority counterparts, which is possibly driven by poor glioblastoma biology.

Racial disparities in pediatric malignant glioma management: current state of affairs in the United States

BACKGROUND

The diagnosis of malignant glioma confers a poor prognosis in the pediatric population. In the adult demographic, racial disparities exist with respect to access to care and survival. Yet to date no efforts have been made to characterize racial disparities in the care of malignant pediatric gliomas. Correspondingly, the aim of this study was to understand if racial disparities exist in the setting of malignant pediatric gliomas.

METHODS

All pediatric malignant gliomas patients with known race status (White, Black, Other) in the US National Cancer Database (NCDB) between the years 2005-2016 were retrospectively reviewed. Demographic, socioeconomic and clinical data were then abstracted and analyzed by comparison and regression techniques.

RESULTS

A total of 1803 pediatric malignant glioma cases were identified, with 48% female and a median age of 8 years old. Brainstem locations were reported in 48% of cases. Socioeconomically, there were statistically significant differences with respect to insurance status, yearly income, household education level and metropolitan residences between the racial groups (all P < 0.01). With respect to treatment, there was statistical difference in the proportion of patients treated with surgical resection (White 43% vs Black 34% vs Other 37%, P = 0.02). There were no differences between race groups for radiation therapy (P = 0.73) or chemotherapy (P = 0.12). The odds of surgical resection were significantly less in the Black group compared to the White group (OR 0.69, P < 0.01), although there was no difference in overall survival between the two groups in those treated with (P = 0.44) or without (P = 0.27) surgical resection. Primary associations of surgical resection in the Black group were brainstem location (P < 0.05) and lower yearly household income quartiles (P < 0.05).

CONCLUSIONS

Racial disparities exist amongst the management of pediatric malignant gliomas, with undefined impact on survival and quality of life. In this perspective, we identified associations between Black patients and access to surgical treatment. Understanding that there are many elements to patient care, including quality of life, should encourage all clinicians and carers to consider racial disparities appropriately when managing malignant pediatric glioma patients.

Disparities in Reported Testing for 1p/19q Codeletion in Oligodendroglioma and Oligoastrocytoma Patients: An Analysis of the National Cancer Database

Purpose

A chromosomal 1p/19q codeletion was included as a required diagnostic component of oligodendrogliomas in the 2016 World Health Organization (WHO) classification of central nervous system tumors. We sought to evaluate disparities in reported testing for 1p/19q codeletion among oligodendroglioma and oligoastrocytoma patients before and after the guidelines.

Methods

The National Cancer Database (NCDB) was queried for patients with histologically-confirmed WHO grade II/III oligodendroglioma or oligoastrocytoma from 2011-2017. Adjusted odds of having a reported 1p/19q codeletion test for patient- and hospital-level factors were calculated before (2011-2015) and after (2017) the guidelines. The adjusted likelihood of receiving adjuvant treatment (chemotherapy and/or radiotherapy) based on reported testing was also evaluated.

Results

Overall, 6,404 patients were identified. The reported 1p/19q codeletion testing rate increased from 45.8% in 2011 to 59.8% in 2017. From 2011-2015, lack of insurance (OR 0.77; 95% CI 0.62-0.97;p=0.025), lower zip code-level educational attainment (OR 0.62; 95% CI 0.49-0.78;p<0.001), and Northeast (OR 0.68; 95% CI 0.57-0.82;p<0.001) or Southern (OR 0.62; 95% CI 0.49-0.79;p<0.001) facility geographic region were negatively associated with reported testing. In 2017, Black race (OR 0.49; 95% CI 0.26-0.91;p=0.024) and Northeast (OR 0.50; 95% CI 0.30-0.84;p=0.009) or Southern (OR 0.42; 95% CI 0.22-0.78;p=0.007) region were negatively associated with reported testing. Patients with a reported test were more likely to receive adjuvant treatment (OR 1.73; 95% CI 1.46-2.04;p<0.001).

Conclusion

Despite the 2016 WHO guidelines, disparities in reported 1p/19q codeletion testing by geographic region persisted while new disparities in race/ethnicity were identified, which may influence oligodendroglioma and oligoastrocytoma patient management.

Physiological and pathological functions of βB2-crystallins in multiple organs: a systematic review

Crystallins, the major constituent proteins of mammalian lenses, are significant not only for the maintenance of eye lens stability, transparency, and refraction, but also fulfill various physiopathological functions in extraocular tissues. βB2-crystallin, for example, is a multifunctional protein expressed in the human retina, brain, testis, ovary, and multiple tumors. Mutations in the βB2 crystallin gene or denaturation of βB2-crystallin protein are associated with cataracts, ocular pathologies, and psychiatric disorders. A prominent role for βB2-crystallins in axonal growth and regeneration, as well as in dendritic outgrowth, has been demonstrated after optic nerve injury. Studies in βB2-crystallin-null mice revealed morphological and functional abnormalities in testis and ovaries, indicating βB2-crystallin contributes to male and female fertility in mice. Interestingly, although pathogenic significance remains obscure, several studies identified a clear correlation between βB2 crystallin expression and the prognosis of patients with breast cancer, colorectal cancer, prostate cancer, renal cell carcinoma, and glioblastoma in the African American population. This review summarizes the physiological and pathological functions of βB2-crystallin in the eye and other organs and tissues and discusses findings related to the expression and potential role of βB2-crystallin in tumors.

African Americans and European Americans exhibit distinct gene expression patterns across tissues and tumors associated with immunologic functions and environmental exposures

The COVID-19 pandemic has affected African American populations disproportionately with respect to prevalence, and mortality. Expression profiles represent snapshots of combined genetic, socio-environmental (including socioeconomic and environmental factors), and physiological effects on the molecular phenotype. As such, they have potential to improve biological understanding of differences among populations, and provide therapeutic biomarkers and environmental mitigation strategies. Here, we undertook a large-scale assessment of patterns of gene expression between African Americans and European Americans, mining RNA-Seq data from 25 non-diseased and diseased (tumor) tissue-types. We observed the widespread enrichment of pathways implicated in COVID-19 and integral to inflammation and reactive oxygen stress. Chemokine CCL3L3 expression is up-regulated in African Americans. GSTM1, encoding a glutathione S-transferase that metabolizes reactive oxygen species and xenobiotics, is upregulated. The little-studied F8A2 gene is up to 40-fold more highly expressed in African Americans; F8A2 encodes HAP40 protein, which mediates endosome movement, potentially altering the cellular response to SARS-CoV-2. African American expression signatures, superimposed on single cell-RNA reference data, reveal increased number or activity of esophageal glandular cells and lung ACE2-positive basal keratinocytes. Our findings establish basal prognostic signatures that can be used to refine approaches to minimize risk of severe infection and improve precision treatment of COVID-19 for African Americans. To enable dissection of causes of divergent molecular phenotypes, we advocate routine inclusion of metadata on genomic and socio-environmental factors for human RNA-sequencing studies.

Role of Ethnicity and Geographic Location on Glioblastoma IDH1/IDH2 Mutations

BACKGROUND

Previous studies have demonstrated possible differences in glioblastoma (GBM) survival attributable to ethnicity. The goal of this study was to quantify oncogenic differences and evaluate the overall survival (OS) and progression-free survival (PFS) differences in GBM patients across race/ethnicity using both population-based surveillance and institutional data sets from the United States (US) and Mexico.

METHODS

Retrospective cohort study comprising the Texas Cancer Registry (TCR, n = 4134) and referral institutions located in US (n = 254) and Mexico (n = 47) were evaluated. Primary outcomes include OS and PFS. Oncogenic differences attributable to ethnicity were assessed. IDH1/IDH2 status was evaluated by sequencing in US and Mexico samples. Kaplan-Meier and Cox proportional hazards regression for survival analysis.

RESULTS

A total of 4134 GBM patients were identified from the TCR data set, ethnicity comparison demonstrated that Hispanic patients were diagnosed at a significantly younger age compared to non-Hispanic white patients (NHW) (median: 58 vs. 62, P < 0.001) and had improved OS (hazard ratio: 0.82, P < 0.001). In the oncogenic analysis, we observed a significant enrichment of IDH1/IDH2 mutations in Mexican Hispanic patients compared to US Hispanic patients (29.8% vs. 7.9%, P = 0.012); IDH2 mutations drove this difference. Post-progression survival was significantly shorter in patients from Mexico than US (3.0 vs. 11.4 months; P < 0.001), while OS remained similar.

CONCLUSIONS

IDH2 mutations are more prevalent in Mexican Hispanic individuals compared to US individuals and may be a crucial contributor to the previously reported survival benefit of Hispanic individuals in large population databases. These findings are critical for both screening of IDH2 mutations and targeted interventions in GBM.

Racial and socioeconomic disparities differentially affect overall and cause-specific survival in glioblastoma

INTRODUCTION

The prognostic role of racial and socioeconomic factors in patients with glioblastoma is controversially debated. We aimed to evaluate how these factors may affect survival outcomes in an overall and cause-specific manner using large, national cancer registry cohort data in the temozolomide chemoradiation era.

METHODS

The National Cancer Institute's Surveillance, Epidemiology, and End Results database was queried for patients diagnosed with glioblastoma between 2005 and 2016. Overall survival was assessed using Cox proportional hazard models using disease intrinsic and extrinsic factors. Cause-specific mortality was assessed using cumulative incidence curves and modeled using multivariate cumulative risk regression.

RESULTS

A total of 28,952 patients met the prespecified inclusion criteria and were included in this analysis. The following factors were associated with all-cause mortality: age, calendar year of diagnosis, sex, treatment receipt, tumor size, tumor location, extent of resection, median household income, and race. Asian/Pacific Islanders and Hispanic Whites had lower mortality compared to Non-Hispanic Whites. Cause-specific mortality was associated with both racial and socioeconomic groups. After adjusting for treatment and tumor-related factors, Asian/Pacific and black patients had lower glioblastoma-specific mortality. However, lower median household income and black race were associated with significantly higher non-glioblastoma mortality.

CONCLUSIONS

Despite the aggressive nature of glioblastoma, racial and socioeconomic factors influence glioblastoma-specific and non-glioblastoma associated mortality. Our study shows that patient race has an impact on glioblastoma-associated mortality independently of tumor and treatment related factors. Importantly, socioeconomic and racial differences largely contribute to non-glioblastoma mortality, including death from other cancers, cardio- and cerebrovascular events.

A functional role for the cancer disparity-linked genes, CRYβB2 and CRYβB2P1, in the promotion of breast cancer

Background

In the USA, the breast cancer mortality rate is 41% higher for African-American women than non-Hispanic White women. While numerous gene expression studies have classified biological features that vary by race and may contribute to poorer outcomes, few studies have experimentally tested these associations. CRYβB2 gene expression has drawn particular interest because of its association with overall survival and African-American ethnicity in multiple cancers. Several reports indicate that overexpression of the CRYβB2 pseudogene, CRYβB2P1, and not CRYβB2 is linked with race and poor outcome. It remains unclear whether either or both genes are linked to breast cancer outcomes. This study investigates CRYβB2 and CRYβB2P1 expression in human breast cancers and breast cancer cell line models, with the goal of elucidating the mechanistic contribution of CRYβB2 and CRYβB2P1 to racial disparities.

Methods

Custom scripts for CRYβB2 or CRYβB2P1 were generated and used to identify reads that uniquely aligned to either gene. Gene expression according to race and tumor subtype were assessed using all available TCGA breast cancer RNA sequencing alignment samples (n = 1221). In addition, triple-negative breast cancer models engineered to have each gene overexpressed or knocked out were developed and evaluated by in vitro, biochemical, and in vivo assays to identify biological functions.

Results

We provide evidence that CRYβB2P1 is expressed at higher levels in breast tumors compared to CRYβB2, but only CRYβB2P1 is significantly increased in African-American tumors relative to White American tumors. We show that independent of CRYβB2, CRYβB2P1 enhances tumorigenesis in vivo via promoting cell proliferation. Our data also reveal that CRYβB2P1 may function as a non-coding RNA to regulate CRYβB2 expression. A key observation is that the combined overexpression of both genes was found to suppress cell growth. CRYβB2 overexpression in triple-negative breast cancers increases invasive cellular behaviors, tumor growth, IL6 production, immune cell chemoattraction, and the expression of metastasis-associated genes. These data underscore that both CRYβB2 and CRYβB2P1 promote tumor growth, but their mechanisms for tumor promotion are likely distinct.

Conclusions

Our findings provide novel data emphasizing the need to distinguish and study the biological effects of both CRYβB2 and CRYβB2P1 as both genes independently promote tumor progression. Our data demonstrate novel molecular mechanisms of two understudied, disparity-linked molecules.

Electronic supplementary material

The online version of this article (10.1186/s13058-019-1191-3) contains supplementary material, which is available to authorized users.

Inhibition of human glioblastoma cell invasion involves PION@E6 mediated autophagy process

Background

Glioblastoma (GBM) is the most severe brain cancer due to its ability to invade surrounding brain tissue. Iron oxide nanoparticles (ION) could effectively induce a decrease of cell migration/invasion. Also IONs could generate ROS stress which induces autophagy elevation. Autophagy is associated with both anti-tumorigenesis and protumorigenesis.

Objective

To explore the effect of PEGylated IONs (PION@E6) on the GBM cell invasion and its mechanism based on autophagy.

Materials and methods

PION@E6 were prepared and characterized according to our previous study. After incubation of U251 cells with PION@E6, cellular uptake of PION@E6 and cell viability were tested by Prussian blue staining and Cell Counting Kit-8, respectively. The migration and invasive capability was assessed by transwell cell migration and invasion assay. Expressions of autophagy biomarkers were detected by Western blotting. Intracellular ROS level was determined using 2′–7′-dichlorodihydrofluorescein diacetate.

Results

Average hydrate particle size and zeta potential of PION@E6 were 37.86±12.90 nm and –23.8 mV, respectively, and uniformly distributed nanoparticles with an average diameter of 10 nm were observed by TEM. Chlorin e6 successfully incorporated onto PION@E6 was demonstrated by ultraviolet and visible absorption spectrophotometry, and PION@E6 owning excellent water solubility and stability were showed by Colloid stability test. PION@E6 were successfully taken up by U251 cells with Prussian blue staining, and they showed in vitro cytotoxicity to glioma cells after long incubation of 72 hours. Migration/invasion of cells was significantly inhibited by PION@E6, which could be counteracted by pretreatment with 3-MA. Additionally, the expression of beclin-1, IC3I, and IC3II proteins was higher, whereas that of p62 protein was lower. Moreover, a dose dependent intracellular ROS generation of PION@E6 was detected.

Conclusion

Invasiveness of human GBM cells involves the PION@E6-mediated autophagy process, which may be related to the intracellular ROS induced by PION@E6.