Aerobic glycolysis supports proliferation through unresolved mechanisms. We have previously shown that aerobic glycolysis is required for the regulated proliferation of cerebellar granule neuron ...progenitors (CGNP) and for the growth of CGNP-derived medulloblastoma. Blocking the initiation of glycolysis via deletion of
(
) disrupts CGNP proliferation and restricts medulloblastoma growth. Here, we assessed whether disrupting
(
), an enzyme that acts in the terminal steps of glycolysis, would alter CGNP metabolism, proliferation, and tumorigenesis. We observed a dichotomous pattern of PKM expression, in which postmitotic neurons throughout the brain expressed the constitutively active PKM1 isoform, while neural progenitors and medulloblastomas exclusively expressed the less active PKM2. Isoform-specific
deletion in CGNPs blocked all
expression.
-deleted CGNPs showed reduced lactate production and increased SHH-driven proliferation.
C-flux analysis showed that
deletion reduced the flow of glucose carbons into lactate and glutamate without markedly increasing glucose-to-ribose flux.
deletion accelerated tumor formation in medulloblastoma-prone
mice, indicating the disrupting PKM releases CGNPs from a tumor-suppressive effect. These findings show that distal and proximal disruptions of glycolysis have opposite effects on proliferation, and that efforts to block the oncogenic effect of aerobic glycolysis must target reactions upstream of PKM.
.
Objective. Study the effect of quality control circle (QCC) in promoting the usage of rubber dams (RD) in root canal treatment of chronic pulpitis in primary teeth. Methods. Set up a quality control ...group to increase the amount of rubber dams used in the treatment of chronic pulpitis in primary teeth. Monthly monitoring results of the usage amount were counted by the outpatient computer system. Relevant data were collected through questionnaires, and causes of low utilization were analyzed, and the improvement measurements were formulated and implemented. Quality control circle activity was evaluated. Results. Through the quality control circle activity, the consumption of rubber dams in the root canal treatment of chronic pulpitis was significantly improved, children in treatment became more cooperative, and operation time of root canal treatment has also been shortened. Conclusion. The quality control circle activities played a significant role in promoting the use of rubber dams in the root canal treatment of primary teeth, and it can be used as a method to promote new clinical treatment programs.
We show that inactivating AMPK in a genetic medulloblastoma model depletes tumor stem cells and slows progression. In medulloblastoma, the most common malignant pediatric brain tumor, drug-resistant ...stem cells co-exist with transit-amplifying cells and terminally differentiated neuronal progeny. Prior studies show that Hk2-dependent glycolysis promotes medulloblastoma progression by suppressing neural differentiation. To determine how the metabolic regulator AMPK affects medulloblastoma growth and differentiation, we inactivated AMPK genetically in medulloblastomas. We bred conditional Prkaa1 and Prkaa2 deletions into medulloblastoma-prone SmoM2 mice and compared SmoM2-driven medulloblastomas with intact or inactivated AMPK. AMPK-inactivation increased event-free survival (EFS) and altered cellular heterogeneity, increasing differentiation and decreasing tumor stem cell populations. Surprisingly, AMPK-inactivation decreased mTORC1 activity and decreased Hk2 expression. Hk2 deletion similarly depleted medulloblastoma stem cells, implicating reduced glycolysis in the AMPK-inactivated phenotype. Our results show that AMPK inactivation disproportionately impairs medulloblastoma stem cell populations typically refractory to conventional therapies.
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•Genetic AMPK inactivation slows tumor progression in SHH medulloblastoma in mice•AMPK-deleted tumors show increased differentiation and reduced proliferation•Disabling AMPK reduces mTORC1 activity and HK2-dependent glycolysis•AMPK inactivation disproportionately impairs medulloblastoma stem cell populations
Molecular biology; Cell biology; Sequence analysis; Cancer; Model organism
Mitochondrial fission and fusion are required for maintaining functional mitochondria. The mitofusins (MFN1 and MFN2) are known for their roles in mediating mitochondrial fusion. Recently, MFN2 has ...been implicated in other important cellular functions, such as mitophagy, mitochondrial motility, and coordinating endoplasmic reticulum-mitochondria communication. In humans, over 100
mutations are associated with a form of inherited peripheral neuropathy, Charcot-Marie-Tooth disease type 2A (CMT2A). Here we describe an ENU-induced mutant mouse line with a recessive neuromuscular phenotype. Behavioral screening showed progressive weight loss and rapid deterioration of motor function beginning at 8 weeks. Mapping and sequencing revealed a missense mutation in exon 18 of
(T1928C; Leu643Pro), within the transmembrane domain. Compared to wild-type and heterozygous littermates,
mice exhibited diminished rotarod performance and decreases in activity in the open field test, muscular endurance, mean mitochondrial diameter, sensory tests, mitochondrial DNA content, and MFN2 protein levels. However, tests of peripheral nerve physiology and histology were largely normal. Mutant leg bones had reduced cortical bone thickness and bone area fraction. Together, our data indicate that
causes a recessive motor phenotype with mild bone and mitochondrial defects in mice. Lack of apparent nerve pathology notwithstanding, this is the first reported mouse model with a mutation in the transmembrane domain of the protein, which may be valuable for researchers studying MFN2 biology.
Abstract
We have proposed that microcephaly-producing mutations identify genes required for growth in the nervous system that may be new targets for brain tumor treatment. We tested this hypothesis ...by deleting the RNA-processing gene Magoh during cerebellar development and medulloblastoma pathogenesis. Magoh mutation has been shown to induce DNA damage and apoptosis in forebrain progenitors, resulting in microcephaly. We conditionally deleted Magoh during postnatal cerebellar neurogenesis by crossing MagohloxP/loxP mice with CAG-CreER transgenic mice (MagohCre-ER). Magoh-deleted cerebellar granule neuron progenitors (CGNPs) of the cerebellum of MagohCre-ER mice showed DNA damage, cell cycle arrest and apoptosis, which depleted the progenitor-rich external granule layer within 72 hrs. Moreover, deleting Magoh in SHH-driven medulloblastomas in SmoA1 mice similarly induced DNA damage, apoptosis and tumor shrinkage. These data show that MAGOH is required for SHH-driven proliferation in both normal cerebellar progenitors and in SHH-driven medulloblastoma. These findings are the first to show that medulloblastoma growth can be disrupted by targeting the RNA processing machinery.
Objectives
This study was designed to explore the effects of mechanical force on the proliferation, apoptosis, and morphology of stem cells from human exfoliated deciduous tooth pulp (SHEDs).
...Materials and methods
Caries-free stranded deciduous teeth were extracted, and SHEDs were isolated through enzymatic digestion. The cultured SHEDs were subjected to different levels of mechanical stimuli (0, 100, 200, and 300 g) for 7 days (30 min/day) using external centrifugal force. Cell proliferation was evaluated with the CCK-8 assay, and the cell cycle and apoptosis were assessed by flow cytometry. The cell morphology was examined using transmission electron microscopy.
Results
Cell proliferation assay showed no differences between the three stimulation groups and the control group in day 1 to day 3. From the 4th day, cell proliferation was significantly lower in the mechanical force groups than in the control group, but no significant difference was observed among the three mechanical force groups. Besides, there was no significant difference in cell apoptosis among the four groups for 7 days. On day 7 after stimulation, the SHEDs were shrunken, with significantly increased isochromosome in the nucleus and an increase in lysosomes.
Conclusions
Mechanical force can inhibit the proliferation and affect morphology of SHEDs, but it has no effect on cell apoptosis.
Clinical relevance
Mechanical force stimulation significantly inhibited cell proliferation of SHEDs. Mechanical force stimulation had no significant effect on cell apoptosis of SHEDs. The morphology and ultrastructure of SHEDs changed after mechanical force stimulation.
Abstract
For the roughly 30% of medulloblastoma patients with SHH-subgroup tumors, drugs that disrupt SHH signaling offer the potential of improved efficacy with reduced toxicity compared to current, ...non-targeted treatment. The FDA-approved SMO inhibitor vismodegib, has been shown to be safe and effective for the treatment of basal cell carcinoma. In SHH-subgroup medulloblastomas, however, initial responses to vismodegib, have been followed by resistance that develops during treatment. We hypothesized that improving the delivery of the drug across the blood-brain barrier would forestall the development of resistance. We developed a novel, nanoparticle formulation of vismodegib, encapsulated in polyoxazoline micelles (POx-vismo). These nanoparticles showed high drug loading, and consistent, nanometer-scale particle size. We treated medulloblastoma bearing GFAP-cre/SmoM2 (G-Smo) mice with either POx-vismo or conventional vismodegib, administered by IP injection at postnatal days 12 and 13 (P12, P13) and then every other day. Both formulations induced an initial response. However, G-Smo mice treated with conventional vismodegib quickly progressed despite therapy. In contrast, POx-vismo-treated mice survived significantly longer than untreated mice or mice treated with conventional vismodegib. Our results show the superiority of POx-vismo and highlight the potential for POx micelles drug delivery to increase the efficacy of approved and experimental agents for brain tumor therapy. The anti-tumor effect of vismodegib, optimized in POx-vismo is significant and may, in combination with additional treatments such as radiation, lead to new treatment approaches.
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