RBM10 truncation in astroblastoma in a patient with history of mandibular ameloblastoma: A case report

Proto-oncogene cSrc-mediated RBM10 phosphorylation arbitrates anti-hypertrophy gene program in the heart and controls cardiac hypertrophy

AIMS

RBM10 is a well-known RNA binding protein that regulates alternative splicing in various disease states. We have shown a splicing-independent function of RBM10 that regulates heart failure. This study aims to unravel a new biological function of RBM10 phosphorylation by proto-oncogene cSrc that enables anti-hypertrophy gene program and controls cardiac hypertrophy.

MATERIALS AND METHODS

We employ in vitro and in vivo approaches to characterise RBM10 phosphorylation at three-tyrosine residues (Y81, Y500, and Y971) by cSrc and target mRNA regulation. We also use isoproterenol induced rat heart and cellular hypertrophy model to determine role of cSrc-mediated RBM10 phosphorylation.

KEY FINDINGS

We show that RBM10 phosphorylation is induced in cellular and animal heart model of cardiac hypertrophy and regulates target mRNA expression and 3'-end formation. Inhibition of cSrc kinase or mutation of the three-tyrosine phosphorylation sites to phenylalanine accentuates myocyte hypertrophy, and results in advancement and an early attainment of hypertrophy in the heart. RBM10 is down regulated in the hypertrophic myocyte and that its re-expression reverses cellular and molecular changes in the myocyte. However, in the absence of phosphorylation (cSrc inhibition or phospho-deficient mutation), restoration of endogenous RBM10 level in the hypertrophic heart or ectopic re-expression in vitro failed to reverse cardiomyocyte hypertrophy. Mechanistically, loss of RBM10 phosphorylation inhibits nuclear localisation and interaction with Star-PAP compromising anti-hypertrophy gene expression.

SIGNIFICANCE

Our study establishes that cSrc-mediated RBM10 phosphorylation arbitrates anti-hypertrophy gene program. We also report a new functional regulation of RBM10 by phosphorylation that is poised to control heart failure.

Neuroimaging of astroblastomas: A case series and systematic review

BACKGROUND AND PURPOSE

Astroblastoma is a rare type of glial tumor, histologically classified into two types with different prognoses: high and low grade. We aimed to investigate the CT and MRI findings of astroblastomas by collecting studies with analyzable neuroimaging data and extracting the imaging features useful for tumor grading.

METHODS

We searched for reports of pathologically proven astroblastomas with analyzable neuroimaging data using PubMed, Scopus, and Embase. Sixty-five studies with 71 patients with astroblastomas met the criteria for a systematic review. We added eight patients from our hospital, resulting in a final study cohort of 79 patients. The proportion of high-grade tumors was compared in groups based on the morphology (typical and atypical) using Fisher's exact test.

RESULTS

High- and low-grade tumors were 35/71 (49.3%) and 36/71 (50.7%), respectively. There was a significant difference in the proportion of high-grade tumors based on the tumor morphology (typical morphology: high-grade = 33/58 [56.9%] vs. atypical morphology, 2/13 [15.4%], p = .012). The reviews of neuroimaging findings were performed using the images included in each article. The articles had missing data due to the heterogeneity of the collected studies.

CONCLUSIONS

Detailed neuroimaging features were clarified, including tumor location, margin status, morphology, CT attenuation, MRI signal intensity, and contrast enhancement pattern. The classification of tumor morphology may help predict the tumor's histological grade, contributing to clinical care and future oncologic research.

RBM10: Structure, functions, and associated diseases

RBM10 is a nuclear RNA-binding protein (RBP) that regulates the alternative splicing of primary transcripts. Recently, research on RBM10 has become increasingly active owing to its clinical importance, as indicated by studies on RBM0 mutations that cause TARP syndrome, an X-linked congenital pleiotropic developmental anomaly, and various cancers such as lung adenocarcinoma in adults. Herein, the molecular biology of RBM10 and its significance in medicine are reviewed, focusing on the gene and protein structures of RBM10, its cell biology, molecular functions and regulation, relationship with the paralogous protein RBM5, and the mutations of RBM10 and their associated diseases. Finally, the challenges in future studies of RBM10 are discussed in the concluding remarks.

Progress in rare central nervous system tumors

PURPOSE OF REVIEW

Although all primary central nervous system (CNS) tumors are rare, certain tumor types each represent less than 2% of the total and an annual incidence of about 1000 patients or less. Most of them are disproportionally diagnosed in children and young adults, but older adults can also be affected and are rarely recruited to clinical trials. Recent new molecular techniques have led to reclassification of some of these tumors and discovery of actionable molecular alterations.

RECENT FINDINGS

We review recent progress in the molecular understanding and therapeutic options of selected rare CNS tumors, with a focus on select clinical trials (temozolomide and lapatinib for recurrent ependymoma; vemurafenib for BRAFV600E-mutated tumors), as well as tumor-agnostic approvals (pembrolizumab, larotrectinib) and their implications for rare CNS tumors.

SUMMARY

Although rare CNS tumors are a very small fraction of the total of cancers, they represent a formidable challenge. There is a need for dedicated clinical trials with strong correlative component in patients of all ages with rare CNS tumors. Critical research questions include relevance of the selected target for specific tumor types, persistence of the actionable biomarker at recurrence, blood-brain barrier penetration, and analysis of mechanisms of primary and acquired resistance.