Glioblastoma preclinical models: Strengths and weaknesses.

Glioblastoma multiforme is a highly malignant brain tumor with significant intra- and intertumoral heterogeneity known for its aggressive nature and poor prognosis. The complex signaling cascade that regulates this heterogeneity makes targeted drug therapy ineffective. The development of an optimal preclinical model is crucial for the comprehension of molecular heterogeneity and enhancing therapeutic efficacy. The ideal model should establish a relationship between various oncogenes and their corresponding responses. This review presents an analysis of preclinical in vivo and in vitro models that have contributed to the advancement of knowledge in model development. The experimental designs utilized in vivo models consisting of both immunodeficient and immunocompetent mice induced with intracranial glioma. The transgenic model was generated using various techniques, like the viral vector delivery system, transposon system, Cre-LoxP model, and CRISPR-Cas9 approaches. The utilization of the patient-derived xenograft model in glioma research is valuable because it closely replicates the human glioma microenvironment, providing evidence of tumor heterogeneity. The utilization of in vitro techniques in the initial stages of research facilitated the comprehension of molecular interactions. However, these techniques are inadequate in reproducing the interactions between cells and extracellular matrix (ECM). As a result, bioengineered 3D-in vitro models, including spheroids, scaffolds, and brain organoids, were developed to cultivate glioma cells in a three-dimensional environment. These models have enabled researchers to understand the influence of ECM on the invasive nature of tumors. Collectively, these preclinical models effectively depict the molecular pathways and facilitate the evaluation of multiple molecules while tailoring drug therapy.

Phosphodiesterase-4 enzyme as a therapeutic target in neurological disorders.

Phosphodiesterases (PDE) are a diverse family of enzymes (11 isoforms so far identified) responsible for the degradation of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) which are involved in several cellular and biochemical functions. Phosphodiesterase 4 (PDE4) is the major isoform within this group and is highly expressed in the mammalian brain. An inverse association between PDE4 and cAMP levels is the key mechanism in various pathophysiological conditions like airway inflammatory diseases-chronic obstruction pulmonary disease (COPD), asthma, psoriasis, rheumatoid arthritis, and neurological disorders etc. In 2011, roflumilast, a PDE4 inhibitor (PDE4I) was approved for the treatment of COPD. Subsequently, other PDE4 inhibitors (PDE4Is) like apremilast and crisaborole were approved by the Food and Drug Administration (FDA) for psoriasis, atopic dermatitis etc. Due to the adverse effects like unbearable nausea and vomiting, dose intolerance and diarrhoea, PDE4 inhibitors have very less clinical compliance. Efforts are being made to develop allosteric modulation with high specificity to PDE4 isoforms having better efficacy and lesser adverse effects. Interestingly, repositioning PDE4Is towards neurological disorders including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), multiple sclerosis (MS) and sleep disorders, is gaining attention. This review is an attempt to summarize the data on the effects of PDE4 overexpression in neurological disorders and the use of PDE4Is and newer allosteric modulators as therapeutic options. We have also compiled a list of on-going clinical trials on PDE4 inhibitors in neurological disorders.

Glioblastoma invasion and NMDA receptors: A novel prospect.

PURPOSE: Glioblastoma cells create glutamate-rich tumor microenvironment, which initiates activation of ion channels and modulates downstream intracellular signaling. N-methyl-D-aspartate receptors (NMDARs; a type of glutamate receptors) have a high affinity for glutamate. The role of NMDAR activation on invasion of glioblastoma cells and the crosstalk with α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) is yet to be explored. MAIN METHODS: LN18, U251MG, and patient-derived glioblastoma cells were stimulated with NMDA to activate NMDAR glutamate receptors. The role of NMDAR activation on invasion and migration and its crosstalk with AMPAR were evaluated. Invasion and migration of glioblastoma cells were investigated by in vitro trans-well Matrigel invasion and trans-well migration assays, respectively. Expression of NMDARs and AMPARs at transcript level was evaluated by quantitative real-time polymerase chain reaction. RESULTS: We determined that NMDA stimulation leads to enhanced invasion in LN18, U251MG, and patient-derived glioblastoma cells, whereas inhibition of NMDAR using MK-801, a non-competitive antagonist of the NMDAR, significantly decreased the invasive capacity. Concordant with these findings, migration was significantly augmented by NMDAR in both cell lines. Furthermore, NMDA stimulation upregulated the expression of GluN2 and GluA1 subunits at the transcript level. CONCLUSIONS: This study demonstrated the previously unexplored role of NMDAR in invasion of glioblastoma cells. Furthermore, the expression of the GluN2 subunit of NMDAR and the differential overexpression of the GluA1 subunit of AMPAR in both cell lines provide a plausible rationale of crosstalk between these calcium-permeable subunits in the glutamate-rich microenvironment of glioblastoma.

A comparative study of serum protein-bound sialic acid in benign and malignant prostatic growth: possible role of oxidative stress in sialic acid homeostasis.

Benign and malignant prostatic growths are associated with an increase in sialoconjugates (e.g. prostate-specific antigen (PSA)) in blood. Oxidative stress plays a crucial role in pathogenesis of various malignancies. The objective of this study was to evaluate oxidative stress parameters and protein-bound sialic acid level in sera of prostatic tumor cases and to asses for any association between them. Sera samples were collected and estimated for carbonylation of proteins, lipid peroxidation products, PSA and protein-bound sialic acid from 10 patients in each group with prostatic carcinoma (Ca prostate) and benign prostatic hyperplasia (BPH) along with 10 healthy male subjects of similar age group as control. In carcinoma prostate cases, lipid peroxides, protein carbonyls, protein-bound sialic acid and PSA were significantly increased compared to BPH and controls. There was significant association between oxidative stress parameters (lipid peroxide and protein carbonyl) and sialoconjugates (PSA and protein-bound sialic acid). In BPH cases, serum lipid peroxides and protein-bound sialic acid were significantly higher in comparison to controls and protein carbonyls were correlated with protein-bound sialic acid. ROC curve for sialic acid showed that it can be used as a marker to differentiate carcinoma prostate from benign growth of prostate at a cutoff level of 11.38 mug/mg protein with a sensitivity of 100% and specificity of 80%. We conclude that oxidative stress might be associated with the degree of sialylation of protein and graded changes in these parameters possibly unveil the pathogenic demarcation from benign to malignant condition of prostate.