Distinct miRNA Expression Signatures of Primary and Secondary Central Nervous System Lymphomas.

Central nervous system (CNS) lymphoma is a rare and aggressive non-Hodgkin lymphoma that might arise in the CNS (primary CNS lymphoma) or disseminates from a systemic lymphoma to the CNS (secondary CNS lymphoma). Dysregulated expression of miRNAs is associated with various pathologic processes, and miRNA expression patterns may have diagnostic, prognostic, and therapeutic implications. However, miRNA expression is understudied in CNS lymphomas. We performed expression analysis of 798 miRNAs in 73 CNS lymphoma samples using the NanoString platform, followed by an analysis to identify potential diagnostic biomarkers characterizing subgroups and to examine differences based on their primary and secondary nature, molecular subtype, mutational patterns, and survival. Thirty-one differentially expressed miRNAs were identified between primary and secondary groups. In addition, 7 more miRNAs were identified associated with a molecular subtype and 25 associated with mutation status. Using unsupervised clustering methods, a small but distinct primary CNS lymphoma subgroup, with characteristically different expression patterns compared with the rest of the cases was defined. Finally, differentially regulated pathways were identified in the above comparisons and the utility of miRNA expression patterns in predicting survival was assessed. Our study identifies a novel CNS lymphoma subgroup defined by distinct miRNAs, proves the importance of specific miRNAs and pathways in the pathogenesis of CNS lymphomas, and provides the basis for future research in defining potential biomarkers.

Molecular Subtypes and Genomic Profile of Primary Central Nervous System Lymphoma.

Primary central nervous system lymphomas (PCNSL) are aggressive non-Hodgkin lymphomas affecting the central nervous system (CNS). Although immunophenotyping studies suggested an uniform activated B-cell (ABC) origin, more recently a spectrum of ABC and germinal center B-cell (GC) cases has been proposed, with the molecular subtypes of PCNSL still being a matter of debate. With the emergence of novel therapies demonstrating different efficacy between the ABC and GC patient groups, precise assignment of molecular subtype is becoming indispensable. To determine the molecular subtype of 77 PCNSL and 17 secondary CNS lymphoma patients, we used the NanoString Lymphoma Subtyping Test (LST), a gene expression-based assay representing a more accurate technique of subtyping compared with standard immunohistochemical (IHC) algorithms. Mutational landscapes of 14 target genes were determined using ultra-deep next-generation sequencing. Using the LST-assay, a significantly lower proportion (80% vs 95%) of PCNSL cases displayed ABC phenotype compared with the IHC-based characterization. The most frequently mutated genes included MYD88, PIM1, and KMT2D. In summary, we successfully applied the LST-assay for molecular classification of PCNSL, reporting higher proportion of cases with GC phenotype compared with IHC analyses, leading to a more precise patient stratification potentially applicable in the diagnostic algorithm of PCNSL.

PD-L1 Expression of Lung Cancer Cells, Unlike Infiltrating Immune Cells, Is Stable and Unaffected by Therapy During Brain Metastasis.

BACKGROUND: Approximately 50% of brain metastases originate from non-small-cell lung cancer. The median survival of patients with brain metastases is 1 month without treatment. Novel immunotherapeutic strategies, such as those targeting the programmed death ligand 1 (PD-L1)/programmed cell death 1 (PD-1) axis, are promising in patients with advanced systemic disease but are often preferentially administered to patients with tumors showing PD-L1 positivity. PATIENTS AND METHODS: Surgically resected paired primary lung adenocarcinoma and brain metastasis samples of 61 patients were analyzed. We compared the paired samples regarding the amount of peritumoral and stromal mononuclear infiltration, PD-L1 expression of tumor and immune cells, and PD-1 expression of immune cells. We investigated the effect of radiotherapy, chemotherapy, and steroid therapy on PD-L1 expression in brain metastases. RESULTS: There was significant positive correlation regarding the PD-L1 expression of tumor cells between the paired primary lung adenocarcinoma and brain metastatic samples with the use of different cutoff levels (1%, 5%, 50%). We found no impact of chemotherapy or steroid therapy on the changes of PD-L1 expression of tumor cells between the 2 sites. There is no or only limited concordance of the proportion of PD-1- or PD-L1-positive tumor-associated immune cells between the paired tumor samples, which suggests that brain metastases develop their own immune environment. CONCLUSION: We observed a strong correlation of PD-L1 positive tumor cells between primary lung adenocarcinoma cases and their corresponding brain metastases, which is not significantly influenced by chemotherapy or steroid therapy.

Discrepancy Between Low Levels of mTOR Activity and High Levels of P-S6 in Primary Central Nervous System Lymphoma May Be Explained by PAS Domain-Containing Serine/Threonine-Protein Kinase-Mediated Phosphorylation.

The primary aim of this study was to determine mTOR-pathway activity in primary central nervous system lymphoma (PCNSL), which could be a potential target for therapy. After demonstrating that p-S6 positivity largely exceeded mTOR activity, we aimed to identify other pathways that may lead to S6 phosphorylation. We measured mTOR activity with immunohistochemistry for p-mTOR and its downstream effectors p(T389)-p70S6K1, p-S6, and p-4E-BP1 in 31 cases of PCNSL and 51 cases of systemic diffuse large B-cell lymphoma (DLBCL) and evaluated alternative S6 phosphorylation pathways with p-RSK, p(T229)-p70S6K1, and PASK antibodies. Finally, we examined the impact of PASK inhibition on S6 phosphorylation on BHD1 cell line. mTOR-pathway activity was significantly less frequent in PCNSL compared with DLBCL. p-S6 positivity was related to mTOR-pathway in DLBCL, but not in PCNSL. Among the other kinases potentially responsible for S6 phosphorylation, PASK proved to be positive in all cases of PCNSL and DLBCL. Inhibition of PASK resulted in reduced expression of p-S6 in BHD1-cells. This is the first study demonstrating an mTOR independent p-S6 activity in PCNSL and that PASK may contribute to the phosphorylation of S6. Our findings also suggest a potential role of PASK in the pathomechanism of PCNSL and in DLBCL.

Evaluating the significance of density, localization, and PD-1/PD-L1 immunopositivity of mononuclear cells in the clinical course of lung adenocarcinoma patients with brain metastasis.

BACKGROUND: Management of lung cancer patients who suffer from brain metastases represents a major challenge. Considering the promising results with immune checkpoint inhibitor treatment, evaluating the status of immune cell (IC) infiltrates in the prognosis of brain metastasis may lead to better therapeutic strategies with these agents. The aim of this study was to characterize the distribution of ICs and determine the expression of the checkpoint molecules programmed death protein 1 (PD-1) and its ligand, PD-L1, in brain metastasis of lung adenocarcinoma (LUAD) patients and to analyze their clinicopathological correlations. METHODS: We determined the presence of peritumoral mononuclear cells (mononuclear ring) and the density of intratumoral stromal mononuclear cells on brain metastasis tissue sections of 208 LUAD patients. PD-L1/PD-1 expressions were analyzed by immunohistochemistry. RESULTS: Mononuclear rings were significantly associated with better survival after brain metastasis surgery. Cases with massive stromal IC infiltration also showed a tendency for better overall survival. Lower expression of PD-1 and PD-L1 was associated with better survival in patients who underwent surgery for the primary tumor and had multiple brain metastases. Steroid administration and chemotherapy appear not to influence the density of IC in brain metastasis. CONCLUSION: This is the first study demonstrating the independent prognostic value of mononuclear rings in LUAD cases with brain metastasis. Our results also suggest that the density of tumor-associated ICs in addition to PD-L1 expression of tumor cells and ICs as well as PD-1 expression of ICs may hold relevant information for the appropriate selection of patients who might benefit from anti-PD-L1 or anti-PD-1 therapy.

Paralemniscal TIP39 is induced in rat dams and may participate in maternal functions.

The paralemniscal area, situated between the pontine reticular formation and the lateral lemniscus in the pontomesencephalic tegmentum contains some tuberoinfundibular peptide of 39 residues (TIP39)-expressing neurons. In the present study, we measured a 4 times increase in the level of TIP39 mRNA in the paralemniscal area of lactating mothers as opposed to nulliparous females and mothers deprived of pups using real-time RT-PCR. In situ hybridization histochemistry and immunolabeling demonstrated that the induction of TIP39 in mothers takes place within the medial paralemniscal nucleus, a cytoarchitectonically distinct part of the paralemniscal area, and that the increase in TIP39 mRNA levels translates into elevated peptide levels in dams. The paralemniscal area has been implicated in maternal control as well as in pain perception. To establish the function of induced TIP39, we investigated the activation of TIP39 neurons in response to pup exposure as maternal, and formalin injection as noxious stimulus. Both stimuli elicited c-fos expression in the paralemniscal area. Subsequent double labeling demonstrated that 95% of neurons expressing Fos in response to pup exposure also contained TIP39 immunoreactivity and 91% of TIP39 neurons showed c-fos activation by pup exposure. In contrast, formalin-induced Fos does not co-localize with TIP39. Instead, most formalin-activated neurons are situated medial to the TIP39 cell group. Our data indicate that paralemniscal neurons may be involved in the processing of maternal and nociceptive information. However, two different groups of paralemniscal neurons participate in the two functions. In particular, TIP39 neurons may participate in the control of maternal functions.

Neuronavigation and fluoroscopy-assisted subdural strip electrode positioning: a simple method to increase intraoperative accuracy of strip localization in epilepsy surgery.

For localization of the epileptogenic zone in cases of focal epilepsy, detailed clinical investigations, imaging studies, and electrophysiological methods are used. If the noninvasive presurgical evaluation provides insufficient data, intracranial electrodes are necessary. Computed tomography and MR imaging techniques are the gold standard for localization of the postoperative position of the implanted intracranial electrode contacts. If the electrode strips are inserted through a bur hole, however, the exact localization of the electrode contacts on the patient's brain remains uncertain for the surgeon during insertion. Therefore, the authors developed a simple method to visualize the electrodes during the procedure. In this method they combine neuronavigation and intraoperative fluoroscopy for parallel visualization of the cortex, electrodes, and the navigation probe. The target region is searched with neuronavigation, a bur hole is made over the optimal entry point, and using real-time fluoroscopy the strip electrode is slid to the tip of the navigation probe, which was kept over the area of interest. At the authors' institution 26 strips in 8 patients have been inserted with this technique, and none of the strips had to be repositioned. There were no complications with this procedure and the prolongation of surgery time is acceptable. Compared to previously published electrode placement methods, this one enhances the accuracy of electrode placement at occipital, parietal, frontal, or interhemispheric regions as well. Intraoperative visualization of the electrodes with fluoroscopy combined with neuronavigation during positioning through a bur hole gives the neurosurgeon the ability to control the real position of the electrode over the gyri during the procedure.

Single-dose contrast agent for intraoperative MR imaging of intrinsic brain tumors by using ferumoxtran-10.

BACKGROUND AND PURPOSE: Intraoperative MR imaging (IMRI) has advantages over conventional framed and frameless techniques. IMRI, however, also has some drawbacks, especially related to interpretation of gadolinium-enhanced intraoperative imaging resulting from surgically induced blood brain barrier injury, vascular changes, and hemorrhage. Ultra-small superparamagnetic iron particles like ferumoxtran-10 have a long plasma half-life and are trapped by reactive cells within the tumor. These trapped particles provide a method to demonstrate enhancing lesions without the artifact of repeat gadolinium administration in the face of blood brain barrier and vascular injury. METHODS: We present a review of the literature and the cases of two patients who underwent surgery in which IMRI with ferumoxtran-10 was used. RESULTS: Ultra-small superparamagnetic iron particles represent a method to demonstrate enhancing intrinsic brain tumors without the drawbacks of intraoperative gadolinium enhancement. These lesions appear even on low-field strength IMRI. Ferumoxtran-10, administered preoperatively, provides a stable imaging marker, even after surgical manipulation of the brain. CONCLUSION: Fermumoxtran-10 provides a way to lessen artifactual enhancement during IMRI related to the administration of gadolinium.