• Cardiovascular
• Diabetes
• Neurodegenerative
• Physiological tetraploidy
• Tetraploidy
• Unphysiological tetraploidy

• Humans
• Tetraploidy
• Animals
• Neoplasms/genetics
• Neoplasms/pathology
• Genomic Instability
• Neurodegenerative Diseases/genetics
• Neurodegenerative Diseases/pathology

• Medical University of Vienna

• Aneuploidy
• Cancer
• Entropy
• Micronuclei
• Systemic
• Tetraploidy

• Humans
• Tetraploidy
• Cell Transformation, Neoplastic/genetics
• Neoplasms/genetics
• Neoplasms/pathology
• Animals
• Epigenesis, Genetic
• Aneuploidy
• Cellular Senescence/genetics

• Aurora kinase B (AURKB)
• BCL2
• Small cell lung cancer (SCLC)

• R21 CA273658 NCI NIH HHS

One mechanism that contributes to cancer recurrence is the ability of some malignant cells to temporarily halt cell division and accumulate multiple nuclei that are later released as progeny, which resume cell division. The release of progeny occurs via primitive cleavage and is highly dependent on the sphingolipid enzyme acid ceramidase but the role of sphingolipid metabolism in this process remains to be elucidated. This study highlights differences in sphingolipid metabolism between non-polyploid and polyploid cancer cells and shows that ceramide synthase 6, which preferentially generates C₁₆-ceramide maximizes the ability of the tumor suppressor p53 to inhibit progeny formation in polyploid cancer cells. These results offer an explanation as to why non-cancerous polyploid cells, which express wildtype p53, do not generate progeny and suggest that cancer cells with deregulated p53 function pose a higher risk of evading therapy especially if enzymes that generate C₁₆-ceramide are also dysregulated.

Polyploid giant cancer cells (PGCC) constitute a transiently senescent subpopulation of cancer cells that arises in response to stress. PGCC are capable of generating progeny via a primitive, cleavage-like cell division that is dependent on the sphingolipid enzyme acid ceramidase (ASAH1). The goal of this study was to understand differences in sphingolipid metabolism between non-polyploid and polyploid cancer cells to gain an understanding of the ASAH1-dependence in the PGCC population. Steady-state and flux analysis of sphingolipids did not support our initial hypothesis that the ASAH1 product sphingosine is rapidly converted into the pro-survival lipid sphingosine-1-phosphate. Instead, our results suggest that ASAH1 activity is important for preventing the accumulation of long chain ceramides such as C₁₆-ceramide. We therefore determined how modulation of C₁₆-ceramide, either through CerS6 or p53, a known PGCC suppressor and enhancer of CerS6-derived C₁₆-ceramide, affected PGCC progeny formation. Co-expression of the CerS6 and p53 abrogated the ability of PGCC to form offspring, suggesting that the two genes form a positive feedback loop. CerS6 enhanced the effect of p53 by significantly increasing protein half-life. Our results support the idea that sphingolipid metabolism is of functional importance in PGCC and that targeting this signaling pathway has potential for clinical intervention.

• cancer
• ceramide
• ceramide synthase
• polyploidy
• sphingolipids: p53

• BRCA1/2
• KRAS
• PIK3CA
• TP53
• gene mutation
• liquids biopsy
• ovarian cancer
• targeted therapy

• Cancer immunotherapy
• DNA repair
• Genetics
• Mouse models
• Oncology

• Aneuploidy
• DNA damage
• genomic instability
• metabolism
• oxidative stress
• proteotoxic stress
• reactive oxygen species (ROS)

Polyploid chromosomes are those with more than two sets of homologous chromosomes. Polyploid chromosomal abnormalities are observed in various malignant tumors. The prognosis in such cases is generally poor. However, there are no studies examining the prognosis of diffuse large B-cell lymphoma (DLBCL) with polyploid chromosomal abnormalities. Therefore, we statistically compared the clinicopathological features between polyploid DLBCL and DLBCL without polyploid abnormalities. Herein, 51 polyploid DLBCL and 53 control (without polyploid chromosomal abnormalities) cases were examined. G-banding method was employed to define polyploidy by cytogenetic analysis. Subsequently, flow cytometric immunophenotyping and immunohistochemical staining were performed. Polyploid DLBCL was defined as DLBCL with either near-tetraploid or greater number of chromosomes, as detected by the G-band. In a survival analysis, a significantly worse overall survival (OS) was observed for polyploid DLBCL (p = 0.04; p = 0.02 in cases who received R-CHOP regimens). In a multivariate analysis of OS, polyploid chromosomal abnormalities were an independent prognostic factor. Our results suggest that polyploid chromosomal abnormalities detected through G-band may represent a new poor prognostic factor for DLBCL.

• Acute myeloid leukemia
• Cytogenetic risk groups
• Tetraploid/near tetraploid karyotype

• G-band
• chromosomal abnormality
• diffuse large B-cell lymphoma
• near-tetraploid
• polyploidy

Alterations in ploidy tend to influence cell physiology, which in the long-term, contribute to species adaptation and evolution. Polyploid cells are observed under physiological conditions in the nerve and liver tissues, and in tumorigenic processes. Although tetraploid cells have been studied in mammalian cells, the basic characteristics and alterations caused by whole genome duplication are still poorly understood. The purpose of this study was to acquire basic knowledge about the effect of whole genome duplication on the cell cycle, cell size, and gene expression. Using flow cytometry, we demonstrate that cell cycle subpopulations in mouse tetraploid embryonic stem cells (TESCs) were similar to those in embryonic stem cells (ESCs). We performed smear preparations and flow cytometric analysis to identify cell size alterations. These indicated that the relative cell volume of TESCs was approximately 2.2–2.5 fold that of ESCs. We also investigated the effect of whole genome duplication on the expression of housekeeping and pluripotency marker genes using quantitative real-time PCR with external RNA. We found that the target transcripts were 2.2 times more abundant in TESCs than those in ESCs. This indicated that gene expression and cell volume increased in parallel. Our findings suggest the existence of a homeostatic mechanism controlling the cytoplasmic transcript levels in accordance with genome volume changes caused by whole genome duplication.

• 5-Fluorouracil
• Human colon cancer
• Multidrug resistance
• Recombinant adenovirus-mediated p53
• Xenografts in nude mice

• Adenoviruses, Human/genetics
• Animals
• Antimetabolites, Antineoplastic/therapeutic use
• Cell Line, Tumor
• Colonic Neoplasms/genetics
• Colonic Neoplasms/pathology
• Colonic Neoplasms/therapy
• Drug Resistance, Neoplasm/genetics
• Female
• Fluorouracil/therapeutic use
• Genes, p53
• Genetic Therapy
• Humans
• Male
• Mice
• Mice, Inbred BALB C
• Mice, Nude
• Mutation

PARP inhibitors have been approved for treatment of tumors with mutations in or loss of BRCA1/2. The molecular mechanisms and particularly the cellular phenotypes resulting in synthetic lethality are not well understood and varying clinical responses have been observed. We have investigated the dose- and time-dependency of cell growth, cell death and cell cycle traverse of 4 malignant lymphocyte cell lines treated with the PARP inhibitor Olaparib. PARP inhibition induced a severe growth inhibition in this cell line panel and increased the levels of phosphorylated H2AX-associated DNA damage in S phase. Repair of the remaining replication related damage caused a G₂ phase delay before entry into mitosis. The G₂ delay, and the growth inhibition, was more pronounced in the absence of functional ATM. Further, Olaparib treated Reh and Granta-519 cells died by apoptosis, while U698 and JVM-2 cells proceeded through mitosis with aberrant chromosomes, skipped cytokinesis, and eventually died by necrosis. The TP53-deficient U698 cells went through several rounds of DNA replication and mitosis without cytokinesis, ending up as multinucleated cells with DNA contents of up to 16c before dying. In summary, we report here for the first time cell cycle-resolved DNA damage induction, and cell line-dependent differences in the mode of cell death caused by PARP inhibition.

• ATM
• DNA damage
• DNA replication
• PARP inhibition
• cell death