Fig 1: SERBP1 affects cancer-related phenotypes and tumor growth. a Knockdown of SERBP1 in U251 cells decreased viability (MTS assay). b SERBP1 silencing diminished clonogenic potential, as measured by colony formation assays. c The Boyden chamber assay was used to evaluate SERBP1 impact on invasion; values of crystal violet absorbance showed that SERBP1 knockdown decreased invasion potential. d–f SERBP1 silencing increased apoptosis as indicated by PARP1 cleavage (d), annexin staining (e), and caspase (f). g GSC proliferation across time was followed with the Incucyte automated system. Decrease in SERBP1 levels impaired cell proliferation. i Knockdown of SERBP1 in GSC lines decreased viability (MTS assays). Data were analyzed with Student’s t test and presented as the mean ± standard deviation. Bonferroni correction was used for multiple comparisons. *p = 0.05; **p = 0.01; ***p = 0.001; ****p = 0.0001. i Intracranial xenografts were established using the shSERBP1 3565 GSC cell line (10 mice per group). Experimental group received Dox to induce expression of shSERBP1. Kaplan-Meier curves indicate that SERBP1 knockdown decreased tumor growth and expanded survival. j Representative Ki67 staining from the tumor boundary for each group. Scale bar = 100 µm
Fig 2: SERBP1 impact on one-carbon and methyl cycles and potential downstream effects. a Metabolic analysis shows that SERBP1 silencing affected the production of metabolites associated with one-carbon, methyl, and MTA cycles. b Intracellular glutathione levels following SERBP1 silencing. c Model for SERBP1 impact on metabolism and functional downstream effects
Fig 3: SERBP1 regulates metabolism. a Enriched Gene Ontology (GO) terms related to genes downregulated upon SERBP1 in U251 cells. Gene set was analyzed using Panther [24] and GO terms were compiled using Revigo [25]; most representative terms associated with metabolism are listed. b Network analysis of genes implicated in metabolism affected by SERBP1 knockdown. Network was built using String [26] considering interaction (experimental evidence), text mining, and co-occurrence. Different colors were used to indicate clusters. c Schematic representation of one-carbon cycle, showing genes affected by SERBP1 knockdown. d, e qRT-PCR and Western blot analysis in U251 and U343 cells corroborated the impact of SERBP1 on the expression of critical genes implicated in metabolism. f Representative PHGDH immunostaining of tumors from the xenograft study for each group. Scale bar = 60 µm
Fig 4: SERBP1 binding motif. a SERBP1 RNA binding motif obtained with RNACompete. b Fluorescence polarization assay shows SERBP1’s high affinity (KD ~ 47 nM) to a 7-mer RNA oligonucleotide (5'- GCGCGGG - 3'). c ~ 40% of transcripts determined via RIP-Seq as preferentially associated with SERBP1 display the identified GC-rich motif in their 3' UTR, a number much higher than expected by chance. d Results of luciferase assay showing that co-transfection of a SERBP1 expression vector increased the expression of reporter constructs containing the 3' UTR of genes displaying putative SERBP1 binding motifs. GAPDH was used as a negative control
Fig 5: SERBP1 expression and impact on glioma survival and therapy. a SERBP1 mRNA expression in normal human tissue based on the GTEx database. b Comparative analysis of SERBP1 mRNA expression in normal brain/cortex (GTEx) and glioma samples (grades II, III, and IV) from the TCGA consortium. c Immunostaining of representative glioma samples (grades II, III, and IV) from the Shanghai Hospital cohort showing SERBP1 protein expression levels. d Kaplan–Meier curves indicate the survival of 177 glioma patients from the Shanghai Changzheng Hospital cohort displaying low and high SERBP1 levels. e–g Kaplan-Meier curves indicate the survival of 118 GBM patients from the Shanghai Changzheng Hospital cohort displaying low and high SERBP1 levels: E (all patients), F (54 patients who received TMZ), and G (83 patients who received radiation)
Supplier Page from DNASU for SERBP1 (Homo sapiens) in pDONR221 (Gateway donor/master vector)