Epari Sridhar

Real-time PCR assay based on the differential expression of microRNAs and protein-coding genes for molecular classification of formalin-fixed paraffin embedded medulloblastomas

BACKGROUND Medulloblastoma has recently been found to consist of 4 molecularly and clinically distinct subgroups: WNT, Sonce hedgehog (SHH), Group 3, and Group 4. Deregulated microRNA expression is known to contribute to pathogenesis and has been shown to have diagnostic and prognostic potential in the classification of various cancers. METHODS Molecular subgrouping and microRNA expression analysis of 44 frozen and 59 formalin-fixed paraffin embedded medulloblastomas from an Indian cohort were carried out by real-time RT-PCR assay. RESULTS The differential expression of 9 microRNAs in the 4 molecular subgroups was validated in a set of 101 medulloblastomas. The tumors in the WNT subgroup showed significant (P < .0001) overexpression of miR-193a-3p, miR-224, miR-148a, miR-23b, and miR-365. Reliable classification of medulloblastomas into the 4 molecular subgroups was obtained using a set of 12 protein-coding genes and 9 microRNAs as markers in a real-time RT-PCR assay with an accuracy of 97% as judged by the Prediction Analysis of Microarrays. Age at diagnosis, histology, gender-related incidence, and the relative survival rates of the 4 molecular subgroups in the present Indian cohort were found to be similar to those reported for medulloblastomas from the American and European subcontinent. Non-WNT, non-SHH medulloblastomas underexpressing miR-592 or overexpressing miR-182 were found to have significantly inferior survival rates, indicating utility of these miRNAs as markers for risk stratification. CONCLUSIONS The microRNA based real-time PCR assay is rapid, simple, inexpensive, and useful for molecular classification and risk stratification of medulloblastomas, in particular formalin-fixed paraffin embedded tissues, wherein the expression profile of protein-coding genes is often less reliable due to RNA fragmentation.

Multipronged quantitative proteomic analyses indicate modulation of various signal transduction pathways in human meningiomas.

Meningiomas (MGs) are frequent tumors of the CNS originating from the meningeal layers of the spinal cord and the brain. In this study, comparative tissue proteomic analysis of low and high grades of MGs was performed by using iTRAQ‐based quantitative proteomics in combination with ESI‐quadrupole‐TOF and Q‐Exactive MS, and results were validated by employing ELISA. Combining the results obtained from two MS platforms, we were able to identify overall 4308 proteins (1% false discover rate), among which 2367 exhibited differential expression (more than and equal to 2 peptide and ≥1.5‐fold in at least one grade) in MGs. Several differentially expressed proteins were found to be associated with diverse signaling pathways, including integrin, Wnt, Ras, epidermal growth factor receptor, and FGR signaling. Proteins, such as vinculin or histones, which act as the signaling activators to initiate multiple signaling pathways, were found to be upregulated in MGs. Quite a few candidates, such as protein S‐100A6, aldehyde dehydrogenase mitochondrial, AHNAK, cytoskeleton‐associated protein 4, and caveolin, showed sequential increase in low‐ and high‐grade MGs, whereas differential expressions of collagen alpha‐1 (VI), protein S100‐A9, 14 kDa phosphohistidine phosphatase, or transgelin‐2 were found to be grade specific. Our findings provide new insights regarding the association of various signal transduction pathways in MG pathogenesis and may introduce new opportunities for the early detection and prognosis of MGs.

Primary CNS hemangiopericytoma presenting as an intraparenchymal mass--case report and review of literature.

Hemangiopericytomas (HPC) are rare, aggressive tumours that mostly involve the musculoskeletal system. They account for less than 1% of intracranial tumours. Intracranially, they are predominantly meningeal based and are thought to arise from the spindle cells (pericytes) in the vicinity of the blood vessels. We present a case of a 69-year-old male with a hemangiopericytoma in the left perisylvian region which was subcortically located. This is an uncommon location. We discuss the case and review the literature.

Quantitative Proteomic Analysis of Meningiomas for the Identification of Surrogate Protein Markers

Meningiomas are the most common non-glial tumors of the brain and spine. Pathophysiology and definite histological grading of meningiomas are frequently found to be deceptive due to their unusual morphological features and locations. Here for the first time we report a comprehensive serum proteomic analysis of different grades of meningiomas by using multiple quantitative proteomic and immunoassay-based approaches to obtain mechanistic insights about disease pathogenesis and identify grade specific protein signatures. In silico functional analysis revealed modulation of different vital physiological pathways including complement and coagulation cascades, metabolism of lipids and lipoproteins, immune signaling, cell growth and apoptosis and integrin signaling in meningiomas. ROC curve analysis demonstrated apolipoprotein E and A-I and hemopexin as efficient predictors for meningiomas. Identified proteins like vimentin, alpha-2-macroglobulin, apolipoprotein B and A-I and antithrombin-III, which exhibited a sequential increase in different malignancy grades of meningiomas, could serve as potential predictive markers.

Intraventricular gliosarcoma: unusual location of an uncommon tumor

Gliosarcomas are uncommon variants of glioblastoma bearing the histological hallmark of two distinct tumor components (high grade glial and sarcomatous). They share similarities with glioblastomas as far as clinico-epidemiological and prognostic factors are concerned. They are commonly cortically-surfacing lesions occurring mostly in the supratentorial compartment. Intraventricular location of a gliosarcoma is very uncommon and reported only once before. We report one such case where the lesion was subependymal and protruded into the ventricle giving the appearance of a truly intraventricluar tumor. We discuss this case and review the relevant literature.

Imaging findings in a rare case of extra-articular chondrocalcinosis.

We report the imaging findings in extra-articular chondrocalcinosis in a 53-year-old man with swelling and pain in right scapular area for 1 year. Plain radiography showed a right scapular area calcific mass. The clinical suspicion was of a soft tissue sarcoma. As a part of diagnostic workup, a bone scan and a PET/CT scan were done. Bone scan revealed intense MDP uptake in the right scapular area. FDG PET/CT revealed intense FDG uptake in the mass. The biopsy revealed chondrocalcinosis. This is an addition to our long list of causes of extraosseous uptake of MDP.

Intracerebral cystic rhabdoid meningioma

A 36-year-old woman presented to our hospital with a short history of intermittent headaches. An MRI of the brain revealed a left temporal intracerebral cystic lesion with rim enhancement. Histopathology showed a malignant tumour with features of rhabdoid differentiation. Immunohistochemistry revealed that vimentin, epithelial membrane antigen and S-100 were positive, and that glial fibrillary acidic protein and the chromosome deletion 1p/19q were negative. The patient was diagnosed as having an intracerebral cystic rhabdoid meningioma. She was treated with surgery and post-operative radiotherapy. Cystic intracerebral rhabdoid meningiomas are rare. We discuss the clinical picture of this patient with reference to the published literature on this uncommon diagnosis.

A retrospective audit of clinicopathological attributes and treatment outcomes of adolescent and young adult non-Hodgkin lymphomas from a tertiary care center

Background: The uniqueness of adolescent and young adult (AYA) non-Hodgkin lymphomas (NHL) with respect to biology and treatment have largely remained unanswered due to marked heterogeneity in treatment, paucity of prospective, or retrospective studies and poor representation of AYA in clinical trials. This audit attempts to put forward the clinicopathological attributes and treatment outcomes of AYA NHL treated with both pediatric and adult protocols from a single centre in a developing country. Patients and Methods: Hospital records of all consecutive NHL patients registered in lymphoma clinic from January 2007 to May 2010 were reviewed for information on demography, clinical features, histology subtype, staging, treatment regimen, response rates, toxicities, and follow up. Two-year progression-free (PFS) and overall survival (OS) were calculated with Kaplan-Meier method. Results: AYA NHL constituted 4% of all lymphomas. Diffuse large B-cell (DLBL) was the most frequent subtype. Following were the 2-year PFS and OS - DLBL 64%, 76.9%, Burkitts lymphoma: 56%, 56%, lymphoblastic lymphoma: 33.2%, 44%. Our results did not show any improvement in outcome of DLBL with the use of Burkitts lymphoma like regimen. Conclusions: This study highlights some of the key features of AYA NHL occurring in developing world.

MiR-206, a Cerebellum Enriched miRNA Is Downregulated in All Medulloblastoma Subgroups and Its Overexpression Is Necessary for Growth Inhibition of Medulloblastoma Cells

Medulloblastoma is the most common and a highly malignant pediatric brain tumor located in the cerebellar region of the brain. Medulloblastomas have recently been shown to consist of four distinct molecular subgroups, viz., WNT, SHH, group 3, and group 4. MiR-206, a miRNA first identified as a myomiR due to its enriched expression in skeletal muscle was found to be expressed specifically in the cerebellum, the site of medulloblastoma occurrence. MiR-206 expression was found to be downregulated in medulloblastomas belonging to all the four molecular subgroups as well as in established medulloblastoma cell lines. Further, the expression of murine homolog of miR-206 was also found to be downregulated in SHH subgroup medulloblastomas from the Smo+/+ transgenic mice and the Ptch1+/− knockout mice. MiR-206 downregulation in all the four medulloblastoma subgroups suggests tumor-suppressive role for miR-206 in medulloblastoma pathogenesis. The effect of miR-206 expression was analyzed in three established medulloblastoma cell lines, viz., Daoy, D425, and D283 belonging to distinct molecular subgroups. Restoration of miR-206 expression to the levels comparable to those in the normal cerebellum, however, was found to be insufficient to inhibit the growth of established medulloblastoma cell lines. OTX2, an oncogenic miR-206 target, overexpressed in all non-SHH medulloblastomas, is known to inhibit myogenic differentiation of medulloblastoma cells. Overexpression of miR-206 was necessary to downregulate OTX2 expression and inhibit growth of medulloblastoma cell lines.

A primary optic nerve sheath chordoid meningioma.

Primary optic nerve sheath meningiomas (ONM) are rare. Most of these are World Health Organization Grade I meningiomas. Because of the intimate relationship to the optic nerve sheath from which they arise, radical excision is often not feasible. The chordoid variant of meningioma is an infrequent tumor and extremely uncommon among primary ONMs. We report a 36-year-old woman with painless proptosis and normal visual acuity who presented to us with an exophytic intraconal mass, which was excised. Histology revealed a chordoid meningioma. We could find only two previous reports, which are discussed.