Genomic Exploration of Distinct Molecular Phenotypes Steering Temozolomide Resistance Development in Patient-Derived Glioblastoma Cells

Chemotherapy using temozolomide is the standard treatment for patients with glioblastoma. Despite treatment, prognosis is still poor largely due to the emergence of temozolomide resistance. This resistance is closely linked to the widely recognized inter- and intra-tumoral heterogeneity in glioblastoma, although the underlying mechanisms are not yet fully understood. To induce temozolomide resistance, we subjected 21 patient-derived glioblastoma cell cultures to Temozolomide treatment for a period of up to 90 days. Prior to treatment, the cells’ molecular characteristics were analyzed using bulk RNA sequencing. Additionally, we performed single-cell RNA sequencing on four of the cell cultures to track the evolution of temozolomide resistance. The induced temozolomide resistance was associated with two distinct phenotypic behaviors, classified as “adaptive” (ADA) or “non-adaptive” (N-ADA) to temozolomide. The ADA phenotype displayed neurodevelopmental and metabolic gene signatures, whereas the N-ADA phenotype expressed genes related to cell cycle regulation, DNA repair, and protein synthesis. Single-cell RNA sequencing revealed that in ADA cell cultures, one or more subpopulations emerged as dominant in the resistant samples, whereas N-ADA cell cultures remained relatively stable. The adaptability and heterogeneity of glioblastoma cells play pivotal roles in temozolomide treatment and contribute to the tumor’s ability to survive. Depending on the tumor’s adaptability potential, subpopulations with acquired resistance mechanisms may arise.</p

Ex vivo drug sensitivity screening predicts response to temozolomide in glioblastoma patients and identifies candidate biomarkers

Background: Patient-derived glioma stem-like cells (GSCs) have become the gold-standard in neuro-oncological research; however, it remains to be established whether loss of in situ microenvironment affects the clinically-predictive value of this model. We implemented a GSC monolayer system to investigate in situ-in vitro molecular correspondence and the relationship between in vitro and patient response to temozolomide (TMZ). Methods: DNA/RNA-sequencing was performed on 56 glioblastoma tissues and 19 derived GSC cultures. Sensitivity to TMZ was screened across 66 GSC cultures. Viability readouts were related to clinical parameters of corresponding patients and whole-transcriptome data. Results: Tumour DNA and RNA sequences revealed strong similarity to corresponding GSCs despite loss of neuronal and immune interactions. In vitro TMZ screening yielded three response categories which significantly correlated with patient survival, therewith providing more specific prediction than the binary MGMT marker. Transcriptome analysis identified 121 genes related to TMZ sensitivity of which 21were validated in external datasets. Conclusion:GSCs retain patient-unique hallmark gene expressions despite loss of their natural environment. Drug screening using GSCs predicted patient response to TMZ more specifically than MGMT status, while transcriptome analysis identified potential biomarkers for this response. GSC drug screening therefore provides a tool to improve drug development and precision medicine for glioblastoma.</p

Transcriptional cdk inhibitors cyc065 and thz1 induce apoptosis in glioma stem cells derived from recurrent gbm

Glioma stem cells (GSCs) are tumour initiating cells which contribute to treatment re-sistance, temozolomide (TMZ) chemotherapy and radiotherapy, in glioblastoma (GBM), the most aggressive adult brain tumour. A major contributor to the uncontrolled tumour cell proliferation in GBM is the hyper activation of cyclin‐dependent kinases (CDKs). Due to resistance to standard of care, GBMs relapse in almost all patients. Targeting GSCs using transcriptional CDK inhibitors, CYC065 and THZ1 is a potential novel treatment to prevent relapse of the tumour. TCGA‐GBM data analysis has shown that the GSC markers, CD133 and CD44 were significantly upregulated in GBM patient tumours compared to non‐tumour tissue. CD133 and CD44 stem cell markers were also expressed in gliomaspheres derived from recurrent GBM tumours. Light Sheet Florescence Microscopy (LSFM) further revealed heterogeneous expression of these GSC markers in glio-maspheres. Gliomaspheres from recurrent tumours were highly sensitive to transcriptional CDK inhibitors, CYC065 and THZ1 and underwent apoptosis while being resistant to TMZ. Apoptotic cell death in GSC subpopulations and non‐stem tumour cells resulted in sphere disruption. Collec-tively, our study highlights the potential of these novel CKIs to induce cell death in GSCs from recurrent tumours, warranting further clinical investigation

LysoPC-acyl C16:0 is associated with brown adipose tissue activity in men.

INTRODUCTION: Brown adipose tissue (BAT) recently emerged as a potential therapeutic target in the treatment of obesity and associated disorders due to its fat-burning capacity. The current gold standard in assessing BAT activity is [(18)F]FDG PET-CT scan, which has severe limitations including radiation exposure, being expensive, and being labor-intensive. Therefore, indirect markers are needed of human BAT activity and volume. OBJECTIVE: We aimed to identify metabolites in serum that are associated with BAT volume and activity in men. METHODS: We assessed 163 metabolites in fasted serum of a cohort of twenty-two healthy lean men (age 24.1 (21.7-26.6) years, BMI 22.1 (20.5-23.4) kg/m(2)) who subsequently underwent a cold-induced [(18)F]FDG PET-CT scan to assess BAT volume and activity. In addition, we included three replication cohorts consisting of in total thirty-seven healthy lean men that were similar with respect to age and BMI compared to the discovery cohort. RESULTS: After correction for multiple testing, fasting concentrations of lysophosphatidylcholine-acyl (LysoPC-acyl) C16:1, LysoPC-acyl C16:0 and phosphatidylcholine-diacyl C32:1 showed strong positive correlations with BAT volume (&beta;=&thinsp;116 (85-148) mL, R(2)&thinsp;=&thinsp;0.81, p&thinsp;=&thinsp;4.6&thinsp;&times;&thinsp;10(-7); &beta;&thinsp;=&thinsp;79 (93-119) mL, R(2)&thinsp;=&thinsp;0.57, p&thinsp;=&thinsp;5.9&thinsp;&times;&thinsp;10(-4) and &beta;=&thinsp;91 (40-141) mL, R(2)&thinsp;=&thinsp;0.52, p&thinsp;=&thinsp;1.0&thinsp;&times;&thinsp;10(-3), respectively) as well as with BAT activity (&beta;=&thinsp;0.20 (0.11-0.29) g/mL, R(2)&thinsp;=&thinsp;0.59, p&thinsp;=&thinsp;1.9&thinsp;&times;&thinsp;10(-4); &beta;&thinsp;=&thinsp;0.15 (0.06-0.23) g/mL, R(2)&thinsp;=&thinsp;0.47, p&thinsp;=&thinsp;2.0&thinsp;&times;&thinsp;10(-3) and &beta;=&thinsp;0.13 (0.01-0.25) g/mL, R(2)&thinsp;=&thinsp;0.28, p&thinsp;=&thinsp;0.04, respectively). When tested in three independent replication cohorts (total n&thinsp;=&thinsp;37), the association remained significant between LysoPC-acyl C16:0 and BAT activity in a pooled analysis (&beta;=&thinsp;0.15 (0.07-0.23) g/mL, R(2)&thinsp;=&thinsp;0.08, p&thinsp;=&thinsp;4.2&thinsp;&times;&thinsp;10(-4)). CONCLUSIONS: LysoPC-acyl C16:0 is associated with BAT activity in men. Since BAT is regarded as a promising tool in the battle against obesity and related disorders, the identification of such a noninvasive marker is highly relevant

Uveal vs. cutaneous melanoma. Origins and causes of the differences.

International audienceMelanoma is a malignant tumour derived from melanocytes (dendritic cells originated from the neural crest and capable to produce melanin synthesis) that could be established on the skin or less frequently on the uvea. The cellular origin from both kind of melanoma seems to be the same but the melanocytes migrates to the epithelia for cutaneous melanoma, while for uveal melanoma, they migrate to mesodermic tissues. Despite the common origin, both melanomas show extreme differences in their metastatic potential, clinical response to treatments, immune response and genetic alterations. We will describe some of those differences in this review