Serum Extracellular Vesicle-Derived circHIPK3 and circSMARCA5 Are Two Novel Diagnostic Biomarkers for Glioblastoma Multiforme

Abstract

Glioblastoma multiforme (GBM) is the most frequent and deadly human brain cancer. Early diagnosis through non-invasive biomarkers may render GBM more easily treatable, improving the prognosis of this currently incurable disease. We suggest the use of serum extracellular vesicle (sEV)-derived circular RNAs (circRNAs) as highly stable minimally invasive diagnostic biomarkers for GBM diagnosis. EVs were isolated by size exclusion chromatography from sera of 23 GBM and 5 grade 3 glioma (GIII) patients, and 10 unaffected controls (UC). The expression of two candidate circRNAs (circSMARCA5 and circHIPK3) was assayed by droplet digital PCR. CircSMARCA5 and circHIPK3 were significantly less abundant in sEVs from GBM patients with respect to UC (fold-change (FC) of −2.15 and −1.92, respectively) and GIII (FC of −1.75 and −1.4, respectively). Receiver operating characteristic curve (ROC) analysis, based on the expression of sEV-derived circSMARCA5 and circHIPK3, allowed us to distinguish GBM from UC (area under the curve (AUC) 0.823 (0.667–0.979) and 0.855 (0.704 to 1.000), with a 95% confidence interval (CI), respectively). Multivariable ROC analysis, performed by combining the expression of sEV-derived circSMARCA5 and circHIPK3 with preoperative neutrophil to lymphocyte (NLR), platelet to lymphocyte (PLR) and lymphocyte to monocyte (LMR) ratios, three known diagnostic and prognostic GBM markers, allowed an improvement in the GBM diagnostic accuracy (AUC 0.901 (0.7912 to 1.000), 95% CI). Our data suggest sEV-derived circSMARCA5 and circHIPK3 as good diagnostic biomarkers for GBM, especially when associated with preoperative NLR, PLR and LMR.

Prognostic Value of the Immunohistochemical Expression of Serine and Arginine-Rich Splicing Factor 1 (SRSF1) in Uveal Melanoma: A Clinico-Pathological and Immunohistochemical Study on a Series of 85 Cases

“…SRSF1 is an RNA-binding protein with proto-oncogenic function, being involved in angiogenesis, cell migration and tumor proliferation of several types of human neoplasms, including gliomas, malignant mesotheliomas, and breast, colorectal and prostate cancers [18,[20][21][22][23][24][25]. SRSF1 immunoexpression was positively associated with worse outcome, androgen-receptor status and Ki-67 proliferation rate in prostatic adenocarcinoma [27]; a significant correlation between SRSF1, MVD and shorter overall survival times was also found in fluoro-edenite-induced malignant mesothelioma [26].…”

“…In the present paper we provided the first immunohistochemical evidence of the poor prognostic role of this protein in UM; in more detail, we found a statistically significant correlation between higher SRSF1 immunohistochemical expression, higher MVD levels and poorer prognosis in terms of metastatic spread and lower metastasis-free-survival in UM. Regarding the relationship between SRSF1 and MVD, previous studies demonstrated that SRSF1 had a stimulatory function on tumor angiogenesis, resulting in a switch in the pro-angiogenic/anti-angiogenic ratio of VEGFA [17][18][19][20][21]; in this regard, Barbagallo et al first reported the complex relationship between circSMARCA5, a specific subtype of circRNAs with a tumor-suppressor role, and SRSF1, demonstrating that the downregulation of circSMARCA5 along with the concomitant upregulation of SRSF1 led to increased cell migration and angiogenesis in human glioblastoma tissue and cell lines [17][18][19]. The MVD count, despite not representing the best method to evaluate tumor angiogenesis, is a semi-quantitative "surrogate" of this process [27]; accordingly, the positive correlation found in our cohort between SRSF1 and MVD led us to hypothesize that SRSF1 has a pro-angiogenic role also in UM.…”

“…Serine and arginine-rich splicing factor 1 (SRSF1) is part of the SR protein family, being involved in canonic and alternative pre-mRNA splicing and in the regulation of mRNA transcription [15,16]. Moreover, SRSF1 has also been reported as a proto-oncogene positively involved in tumor angiogenesis by regulating the alternative splicing of vascular endothelial growth factor-α (VEGFA) [17][18][19][20][21]. In this regard, it has been suggested that SRSF1 tends to promote the formation of the pro-angiogenic isoform of VEGFA, instead of the anti-angiogenic one [17][18][19][20][21].…”

“…Moreover, SRSF1 has also been reported as a proto-oncogene positively involved in tumor angiogenesis by regulating the alternative splicing of vascular endothelial growth factor-α (VEGFA) [17][18][19][20][21]. In this regard, it has been suggested that SRSF1 tends to promote the formation of the pro-angiogenic isoform of VEGFA, instead of the anti-angiogenic one [17][18][19][20][21]. Consistent with its stimulatory role on tumor angiogenesis, SRSF1 has been found overexpressed in several human neoplasms, including prostate, brain, breast, colorectal, liver, pleural and lung tumors [20,[22][23][24][25][26][27]; however, to the best of our knowledge, no data on the role of this protein in UM are present in literature to date.…”

A Preclinical Investigation of GBM-N019 as a Potential Inhibitor of Glioblastoma via Exosomal mTOR/CDK6/STAT3 Signaling

“…Furthermore, the existence of glioma-initiating cells (GICs) a type of glioma stem cell (GSC), mediates treatment failure, tumor recurrence, and invasive phenotypes of GBM [ 4 ]. As a carrier of oncogenes/proteins and other genetic information, exosomes are involved in the conversion of non-GSCs to GSCs and participate in stabilizing the GSC phenotypic integrity [ 5 ]. GBM is also characterized by complex and heterogeneous genotypes which limit the efficacy of drugs that target specific oncogenic signaling axes [ 6 ].…”