Assessment of ApoC1, LuzP6, C12orf75 and OCC-1 in cystic glioblastoma using MALDI–TOF mass spectrometry, immunohistochemistry and qRT-PCR

Abstract

Mass spectrometric analysis of glioblastoma cyst fluids has disclosed a protein peak with m/z 6424–6433. Among the proteins, potentially generating this peak are ApoC1 and LuzP6. To further elucidate protein expression of glioblastoma cells, we analyzed MALDI–TOF results of cyst fluid, performed immunohistochemistry and mRNA analysis. MALDI–TOF protein extraction from 24 glioblastoma cyst fluids was performed with a weak cation exchange. 50 glioblastoma samples were stained with two custom-made antibodies against LuzP6 and commercial antibodies against ApoC1, C12orf75 and OCC-1 and analyzed. For mRNA detection, 16 tissue samples were stored in RNAlater, extracted using the miRNeasy kit and reversely transcribed. For 12 patients, synopsis of results from all three examinations was possible. MALDI–TOF confirmed the peak at 6433 Da in 75% of samples. Immunohistochemically, LuzP6 was detected in 92% (LuzP61–29) and 96% (LuzP630–58) of samples and ApoC1 in 66%. Mean mRNA levels were highest for ApoC1, followed by LuzP6. No correlation between mRNA expression, immunohistochemical staining and intensity of the MALDI–TOF peaks was found. An unequivocal identification of one protein as the source for the 6433 peak is not possible, but our results point to ApoC1 and LuzP6 as the underlying proteins.Electronic supplementary materialThe online version of this article (10.1007/s00795-019-00223-8) contains supplementary material, which is available to authorized users.

Modulation of retinoid-X-receptors differentially regulates expression of apolipoprotein genes apoc1 and apoeb by zebrafish microglia

“…4 K,L), we were interested in determining how microglial expression of apoc1 may be induced, and to investigate how that may be similar or different from that of apoeb. Coordinate regulation of the apolipoprotein gene cluster has been reported ( Cudaback et al, 2012 ; Evangelou et al, 2019 ; Mak et al, 2002 ). Various in vitro studies have examined the role of LXR-RXR and PPAR-RXR receptors in the regulation of the apolipoprotein gene cluster in macrophages and other cell types in vitro ( Chawla et al, 2001 ; Dahabreh and Medh, 2012 ; Mak et al, 2002 ; Subramanian et al, 2017 ).…”

“…Further, due to regulated blood-CNS permeability and transport, maintaining cholesterol and lipid homeostasis in the CNS could be achieved via various pathways including those using recycling and/or efflux, and may be dependent on glial cells (Mauch et al, 2001;Tracey et al, 2018;Yin et al, 2021). Previous reports have suggested that genes in the apolipoprotein cluster are coordinately regulated (Cudaback et al, 2012;Evangelou et al, 2019;Mak et al, 2002). However, our results suggest that PPAR-RXR and LXR-RXR receptors can differentially regulate apoc1 and apoeb in zebrafish microglia.…”

“…Previous reports have suggested that genes in the apolipoprotein cluster are coordinately regulated ( Cudaback et al, 2012 ; Evangelou et al, 2019 ; Mak et al, 2002 ). However, our results suggest that PPAR-RXR and LXR-RXR receptors can differentially regulate apoc1 and apoeb in zebrafish microglia.…”

“…Although the above referenced RNA-seq experiments, including our own, indicate that microglia are a prominent cell type expressing Apoc1 in the CNS, to our knowledge this has not been demonstrated in situ . Though Apoc1 mRNA has been detected in cultured astrocytes ( Petit-Turcotte et al, 2001 ), it is not clear if or when this is the case in vivo , and localization of the protein appears to occur at other locations in the CNS ( Abildayeva et al, 2008 ; Evangelou et al, 2019 ; Petit-Turcotte et al, 2001 ). In addition, although apolipoprotein expression by peripheral macrophages has been studied in terms of lipoprotein metabolism ( Fuior and Gafencu, 2019 ), Apoc1 has received little attention compared to other apolipoprotein genes, most notably Apoe .…”

A Circulating Exosome RNA Signature Is a Potential Diagnostic Marker for Pancreatic Cancer, a Systematic Study

“…It may elicit an immune response in individuals with myeloproliferative disease who have received interferon alpha [ 70 ]. Another study showed that the LUZP6 protein was positive in the majority of glioblastoma [ 71 ], suggesting that it may also be related to tumorigenesis. Interestingly, LUZP6 RNA is enriched in salivary exosomes and, together with another three genes ( IL1R2 , VPS4B and CAP1 ) comprising an RNA signature, could distinguish high from low insulin resistance as an extracellular RNA marker [ 72 ].…”