Urban dust particles disrupt mitotic progression by dysregulating Aurora kinase B-related functions.

Particulate matter (PM), a major component of outdoor air pollution, damages DNA and increases the risk of cancer. Although the harmful effects of PM at the genomic level are known, the detailed mechanism by which PM affects chromosomal stability remains unclear. In this study, we investigated the novel effects of PM on mitotic progression and identified the underlying mechanisms. Gene set enrichment analysis of lung cancer patients residing in countries with high PM concentrations revealed the downregulation of genes associated with mitosis and mitotic structures. We also showed that exposure of lung cancer cells in vitro to urban dust particles (UDPs) inhibits cell proliferation through a prolonged M phase. The mitotic spindles in UDP-treated cells were hyperstabilized, and the number of centrioles increased. The rate of ingression of the cleavage furrow and actin clearance from the polar cortex was reduced significantly. The defects in mitotic progression were attributed to inactivation of Aurora B at kinetochore during early mitosis, and spindle midzone and midbody during late mitosis. While previous studies demonstrated possible links between PM and mitosis, they did not specifically identify the dysregulation of spatiotemporal dynamics of mitotic proteins and structures (e.g., microtubules, centrosomes, cleavage furrow, and equatorial and polar cortex), which results in the accumulation of chromosomal instability, ultimately contributing to carcinogenicity. The data highlight the novel scientific problem of PM-induced mitotic disruption. Additionally, we introduce a practical visual method for assessing the genotoxic outcomes of airborne pollutants, which has implications for future environmental and public health research.

Mild exposure to fine particulate matter promotes angiogenesis in non-small cell lung carcinoma.

Fine particulate matter (PM2.5) is associated with public health problems worldwide. Especially, PM2.5 induces epigenetic and microenvironmental changes in lung cancer. Angiogenesis is important for the development and growth of cancer and is mediated by angiogenic factors, including vascular endothelial growth factor. However, the effects of mild PM2.5 exposure on angiogenesis in lung cancer remain unclear. In this study, we examined angiogenic effects using relatively lower concentrations of PM2.5 than in other studies and found that PM2.5 increased angiogenic activities in both endothelial cells and non-small cell lung carcinoma cells. PM2.5 also promoted the growth and angiogenesis of lung cancer via the induction of hypoxia-inducible factor-1α (HIF-1α) in a xenograft mouse tumor model. Angiogenic factors, including vascular endothelial growth factor (VEGF), were highly expressed in lung cancer patients in countries with high PM2.5 levels in the atmosphere, and high expression of VEGF in lung cancer patients lowered the survival rate. Collectively, these results provide new insight into the mechanisms by which mild exposure to PM2.5 is involved in HIF-1α-mediated angiogenesis in lung cancer patients.

Management of Contacts of the First Imported Monkeypox Case in Korea.

On 22 June, a man who returned to South Korea from Germany tested positive for the monkeypox virus using real-time polymerase chain reaction. We identified 49 contacts concerning the first monkeypox case and classified them into two groups based on risk exposure levels. Through active monitoring of eight people in the medium-risk group and passive monitoring of 41 people in the low-risk group, we identified that no secondary transmission occurred over 21 days. The prompt active or passive monitoring of the index case of imported monkeypox could prevent community transmission in Korea.

CCAR2 controls mitotic progression through spatiotemporal regulation of Aurora B.

CCAR2 (cell cycle and apoptosis regulator 2) is a multifaceted protein involved in cell survival and death following cytotoxic stress. However, little is known about the physiological functions of CCAR2 in regulating cell proliferation in the absence of external stimuli. The present study shows that CCAR2-deficient cells possess multilobulated nuclei, suggesting a defect in cell division. In particular, the duration of mitotic phase was perturbed. This disturbance of mitotic progression resulted from premature loss of cohesion with the centromere, and inactivation of the spindle assembly checkpoint during prometaphase and metaphase. It resulted in the formation of lagging chromosomes during anaphase, leading ultimately to the activation of the abscission checkpoint to halt cytokinesis. The CCAR2-dependent mitotic progression was related to spatiotemporal regulation of active Aurora B. In conclusion, the results suggest that CCAR2 governs mitotic events, including proper chromosome segregation and cytokinetic division, to maintain chromosomal stability.

Integrated bioinformatic analysis of gene expression profiling data to identify combinatorial biomarkers in inflammatory skin disease.

Selection of appropriate biomarker to identify inflammatory skin diseases is complicated by the involvement of thousands of differentially expressed genes (DEGs) across multiple cell types and organs. This study aimed to identify combinatorial biomarkers in inflammatory skin diseases. From one gene expression microarray profiling dataset, we performed bioinformatic analyses on dataset from lesional skin biopsies of patients with inflammatory skin diseases (atopic dermatitis [AD], contact eczema [KE], lichen planus [Li], psoriasis vulgaris [Pso]) and healthy controls to identify the involved pathways, predict upstream regulators, and potential measurable extracellular biomarkers. Overall, 434, 629, 581, and 738 DEGs were mapped in AD, KE, Li, and Pso, respectively; 238 identified DEGs were shared among four different inflammatory skin diseases. Bioinformatic analysis on four inflammatory skin diseases showed significant activation of pathways with known pathogenic relevance. Common upstream regulators, with upregulated predicted activity, identified were CNR1 and BMP4. We found the following common serum biomarkers: ACR, APOE, ASIP, CRISP1, DKK1, IL12B, IL9, MANF, MDK, NRTN, PCSK5, and VEGFC. Considerable differences of gene expression changes, involved pathways, upstream regulators, and biomarkers were found in different inflammatory skin diseases. Integrated bioinformatic analysis identified 12 potential common biomarkers of inflammatory skin diseases requiring further evaluation.

Importation and Transmission of SARS-CoV-2 B.1.1.529 (Omicron) Variant of Concern in Korea, November 2021.

In November 2021, 14 international travel-related severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 (omicron) variant of concern (VOC) patients were detected in South Korea. Epidemiologic investigation revealed community transmission of the omicron VOC. A total of 80 SARS-CoV-2 omicron VOC-positive patients were identified until December 10, 2021 and 66 of them reported no relation to the international travel. There may be more transmissions with this VOC in Korea than reported.

SIRT2 Affects Primary Cilia Formation by Regulating mTOR Signaling in Retinal Pigmented Epithelial Cells.

SIRT2, a member of the Class III HDAC family, participates in diverse cellular processes and regulates several pathological conditions. Although a few reports show that SIRT2 regulates the cell cycle, the causes and outcomes of SIRT2-dependent cell proliferation remain unclear. Here, we examined the effects of SIRT2 suppression in human RPE1 cells using siRNA targeting SIRT2, and AK-1, a SIRT2-specific inhibitor. The number of primary cilia in SIRT2-suppressed cells increased under serum-present conditions. Suppressing SIRT2 induced cell cycle arrest at G0/G1 phase by inactivating mammalian target of rapamycin (mTOR) signaling, possibly through mTORC1. Treatment with torin 1, an inhibitor of mTORC1/mTORC2, yielded results similar to those observed after SIRT2 suppression. However, SIRT2 suppression did not affect primary cilia formation or mTOR signaling following serum starvation. This suggests that SIRT2 acts as a critical sensor that links growth factor-dependent signal transduction and primary cilia formation by regulating the cell cycle.

Bookmarking by histone methylation ensures chromosomal integrity during mitosis.

The cell cycle is an orchestrated process that replicates DNA and transmits genetic information to daughter cells. Cell cycle progression is governed by diverse histone modifications that control gene transcription in a timely fashion. Histone modifications also regulate cell cycle progression by marking specific chromatic regions. While many reviews have covered histone phosphorylation and acetylation as regulators of the cell cycle, little attention has been paid to the roles of histone methylation in the faithful progression of mitosis. Indeed, specific histone methylations occurring before, during, or after mitosis affect kinetochore assembly and chromosome condensation and segregation. In addition to timing, histone methylations specify the chromatin regions such as chromosome arms, pericentromere, and centromere. Therefore, spatiotemporal programming of histone methylations ensures epigenetic inheritance through mitosis. This review mainly discusses histone methylations and their relevance to mitotic progression.

CCAR2/DBC1 and Hsp60 Positively Regulate Expression of Survivin in Neuroblastoma Cells.

CCAR2 (cell cycle and apoptosis regulator 2) controls a variety of cellular functions; however, its main function is to regulate cell survival and cell death in response to genotoxic and metabolic stresses. Recently, we reported that CCAR2 protects cells from apoptosis following mitochondrial stress, possibly by co-operating with Hsp60. However, it is not clear how CCAR2 and Hsp60 control cell survival and death. Here, we found that depleting CCAR2 and Hsp60 downregulated expression of survivin, a member of the inhibitor of apoptosis (IAP) family. Survivin expression in neuroblastoma tissues and human cancer cell lines correlated positively with expression of CCAR2 and Hsp60. Furthermore, high expression of CCAR2, Hsp60, and survivin was associated with poor survival of neuroblastoma patients. In summary, both CCAR2 and Hsp60 are required for expression of survivin, and both promote cancer cell survival, at least in part, by maintaining survivin expression. Therefore, CCAR2, Hsp60, and survivin are candidate tumor biomarkers and prognostic markers in neuroblastomas.

An Aurora kinase inhibitor, AMG900, inhibits glioblastoma cell proliferation by disrupting mitotic progression.

The Aurora kinase family of serine/threonine protein kinases comprises Aurora A, B, and C and plays an important role in mitotic progression. Several inhibitors of Aurora kinase have been developed as anti-cancer therapeutics. Here, we examined the effects of a pan-Aurora kinase inhibitor, AMG900, against glioblastoma cells. AMG900 inhibited proliferation of A172, U-87MG, and U-118MG glioblastoma cells by upregulating p53 and p21 and subsequently inducing cell cycle arrest and senescence. Abnormal cell cycle progression was triggered by dysregulated mitosis. Mitosis was prolonged due to a defect in mitotic spindle assembly. Despite the presence of an unattached kinetochore, BubR1, a component of the spindle assembly checkpoint, was not recruited. In addition, Aurora B was not recruited to central spindle at anaphase. Abnormal mitotic progression resulted in accumulation of multinuclei and micronuclei, a type of chromosome missegregation, and ultimately inhibited cell survival. Therefore, the data suggest that AMG900-mediated inhibition of Aurora kinase is a potential anti-cancer therapy for glioblastoma.

Zingerone Suppresses Tumor Development through Decreasing Cyclin D1 Expression and Inducing Mitotic Arrest.

Cancer cells undergo uncontrolled proliferation resulting from aberrant activity of various cell-cycle proteins. Therefore, despite recent advances in intensive chemotherapy, it is difficult to cure cancer completely. Recently, cell-cycle regulators became attractive targets in cancer therapy. Zingerone, a phenolic compound isolated from ginger, is a nontoxic and inexpensive compound with varied pharmacological activities. In this study, the therapeutic effect of zingerone as an anti-mitotic agent in human neuroblastoma cells was investigated. Following treatment of BE(2)-M17 cells with zingerone, we performed a 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay and colony-formation assay to evaluate cellular proliferation, in addition to immunofluorescence cytochemistry and flow cytometry to examine the mitotic cells. The association of gene expression with tumor stage and survival was analyzed. Furthermore, to examine the anti-cancer effect of zingerone, we applied a BALB/c mouse-tumor model using a BALB/c-derived adenocarcinoma cell line. In human neuroblastoma cells, zingerone inhibited cellular viability and survival. Moreover, the number of mitotic cells, particularly those in prometaphase, increased in zingerone-treated neuroblastoma cells. Regarding specific molecular mechanisms, zingerone decreased cyclin D1 expression and induced the cleavage of caspase-3 and poly (ADP-ribose) polymerase 1 (PARP-1). The decrease in cyclin D1 and increase in histone H3 phosphorylated (p)-Ser10 were confirmed by immunohistochemistry in tumor tissues administered with zingerone. These results suggest that zingerone induces mitotic arrest followed by inhibition of growth of neuroblastoma cells. Collectively, zingerone may be a potential therapeutic drug for human cancers, including neuroblastoma.

The Protein Phosphatase PPM1G Destabilizes HIF-1α Expression.

Hypoxia-inducible factors (HIFs) are key regulators of hypoxic responses, and their stability and transcriptional activity are controlled by several kinases. However, the regulation of HIF by protein phosphatases has not been thoroughly investigated. Here, we found that overexpression of Mg2+/Mn2+-dependent protein phosphatase 1 gamma (PPM1G), one of Ser/Thr protein phosphatases, downregulated protein expression of ectopic HIF-1α under normoxic or acute hypoxic conditions. In addition, the deficiency of PPM1G upregulated protein expression of endogenous HIF-1α under normoxic or acute oxidative stress conditions. PPM1G decreased expression of HIF-1α via the proteasomal pathway. PPM1G-mediated HIF-1α degradation was dependent on prolyl hydroxylase (PHD), but independent of von Hippel-Lindau (VHL). These data suggest that PPM1G is critical for the control of HIF-1α-dependent responses.

CCAR2 negatively regulates IL-8 production in cervical cancer cells.

Cell cycle and apoptosis regulator 2 (CCAR2) is a multifaceted protein that controls diverse cellular functions; however, its function in cancer is unclear. To better understand its potential role in cancer, we examined gene expression patterns regulated by CCAR2 in cervical cancer cells. Cytokine and chemokine production by CCAR2-deficient cells increased under oxidative conditions. In particular, H2O2-treated CCAR2-depleted cells showed a significant increase in interleukin-8 (IL-8) production, indicating a negative regulation of IL-8 by CCAR2. Upregulation of IL-8 expression in CCAR2-deficient cells occurred via activation of transcription factor AP-1. The negative correlation between CCAR2 and IL-8 expression was confirmed by examining mRNA and protein levels in tissues from cervical cancer patients. Furthermore, CCAR2-regulated IL-8 expression is associated with a shorter survival of cervical cancer patients. Overall, the data suggest that CCAR2 plays a critical role in controlling both the cancer secretome and cancer progression.

Glutaminase 2 expression is associated with regional heterogeneity of 5-aminolevulinic acid fluorescence in glioblastoma.

Fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA) is now a widely-used modality for glioblastoma (GBM) treatment. However, intratumoral heterogeneity of fluorescence intensity may reflect different onco-metabolic programs. Here, we investigated the metabolic mechanism underlying the heterogeneity of 5-ALA fluorescence in GBM. Using an in-house developed fluorescence quantification system for tumor tissues, we collected 3 types of GBM tissues on the basis of their fluorescence intensity, which was characterized as strong, weak, and none. Expression profiling by RNA-sequencing revealed 77 genes with a proportional relationship and 509 genes with an inverse relationship between gene expression and fluorescence intensity. Functional analysis and in vitro experiments confirmed glutaminase 2 (GLS2) as a key gene associated with the fluorescence heterogeneity. Subsequent metabolite profiling discovered that insufficient NADPH due to GLS2 underexpression was responsible for the delayed metabolism of 5-ALA and accumulation of protoporphyrin IX (PpIX) in the high fluorescence area. The expression level of GLS2 and related NADPH production capacity is associated with the regional heterogeneity of 5-ALA fluorescence in GBM.

A subpopulation of cancer stem cells identifies radiographic characteristics in glioblastoma.

Cancer stem cells (CSCs), defined by CD133 expression, harbor heterogeneous subpopulations of cells, including endothelial progenitor cells (EPCs). This study aimed to investigate whether a subpopulation of CSCs could affect the radiographic characteristics of glioblastoma. Tissue samples from 10 patients newly diagnosed with glioblastoma were selected according to the radiographic characteristics of their tumors. The patients were divided into two groups based on preoperative magnetic resonance imaging demonstrating contrast enhancement, necrosis and infiltrative patterns: the enhancement/necrosis group (E/N, n=5) and the non-enhancement/infiltration group (NE/I, n=5). Flow cytometry was used to assess the CSCs while immunohistochemistry was used to study microvessel density and the proliferation index. The EPC (CD34+/CD133+) fraction in CSCs (CD133+) was larger in the NE/I group. However, there was little difference in the angiogenic activity assessed using microvessel density between the two groups. The proliferation index (assessed using the antibody Ki-67) was higher in the E/N group and was negatively correlated with the EPC fraction. The non-EPC (CD34-/CD133+) fraction is a major factor responsible for radiographic characteristics of contrast enhancement, thus establishing an association between a subpopulation fraction of CSCs and radiographic characteristics in glioblastoma. Therefore, the simple non-invasive assessment of studying contrast enhancement lesions in glioblastomas may be used to estimate CSC subpopulations.

Mitochondrial CCAR2/DBC1 is required for cell survival against rotenone-induced mitochondrial stress.

CCAR2 (cell cycle and apoptosis regulator protein 2; formerly DBC1, deleted in breast cancer 1) functions in diverse cellular processes including responses to genotoxic and metabolic stresses. However, its role in the mitochondrial stress response has not been fully elucidated. To investigate how CCAR2 regulates stress response, we purified CCAR2-containing complexes. Interestingly, the results revealed that CCAR2 localized to the mitochondria, and also bound Hsp60 (heat shock protein 60), a mitochondrial chaperone. The binding of CCAR2 to Hsp60 increased following rotenone-induced mitochondrial stress. The deficiencies in CCAR2 and Hsp60 also disrupted the mitochondrial membrane potential, thereby promoting apoptosis following mitochondrial stress. In summary, the CCAR2-Hsp60 complex promoted cell survival during mitochondrial stress-induced apoptosis. These data suggest that CCAR2 is critical for maintaining mitochondrial homeostasis in response to stress.

TC Mps1 12, a novel Mps1 inhibitor, suppresses the growth of hepatocellular carcinoma cells via the accumulation of chromosomal instability.

BACKGROUND AND PURPOSE: Chromosomal instability is not only a hallmark of cancer but also an attractive therapeutic target. A diverse set of mitotic kinases maintains chromosomal stability. One of these is monopolar spindle 1 (Mps1, also known as TTK), which is essential for chromosome alignment and for the spindle assembly checkpoint (SAC). Pharmacological inhibition of Mps1 has been suggested as a cancer therapeutic; however, despite the existence of a novel Mps1 inhibitor, TC Mps1 12, no such studies have been performed. EXPERIMENTAL APPROACH: The effects of TC Mps1 12 on cell viability, chromosome alignment, centrosome number, mitotic duration, apoptosis and SAC were determined in hepatocellular carcinoma (HCC) cells. In addition, the association of Mps1 expression with the overall survival of HCC patients was analysed. KEY RESULTS: Treatment of human HCC cells with TC Mps1 12 led to chromosome misalignment and missegregation, and disorganization of centrosomes. Even in the presence of these errors, TC Mps1 12-treated cells overrode the SAC, resulting in a shortened mitotic duration and mitotic slippage. This mitotic catastrophe triggered apoptosis and, finally, inhibited the growth of HCC cells. In addition, the expression of the Mps1-encoding TTK gene was associated with poor overall survival of HCC patients. CONCLUSION AND IMPLICATIONS: TC Mps1 12 results in the accumulation of chromosomal instabilities and mitotic catastrophe in HCC cells. Overall, these data demonstrate that the inhibition of Mps1 kinase using TC Mps1 12 is a promising therapeutic approach for liver cancer.

Underexpression of HOXA11 Is Associated with Treatment Resistance and Poor Prognosis in Glioblastoma.

PURPOSE: Homeobox (HOX) genes are essential developmental regulators that should normally be in the silenced state in an adult brain. The aberrant expression of HOX genes has been associated with the prognosis of many cancer types, including glioblastoma (GBM). This study examined the identity and role of HOX genes affecting GBM prognosis and treatment resistance. MATERIALS AND METHODS: The full series of HOX genes of five pairs of initial and recurrent human GBM samples were screened by microarray analysis to determine the most plausible candidate responsible for GBM prognosis. Another 20 newly diagnosed GBM samples were used for prognostic validation. In vitro experiments were performed to confirm the role of HOX in treatment resistance. Mediators involved in HOX gene regulation were searched using differentially expressed gene analysis, gene set enrichment tests, and network analysis. RESULTS: The underexpression of HOXA11 was identified as a consistent signature for a poor prognosis among the HOX genes. The overall survival of the GBM patients indicated a significantly favorable prognosis in patients with high HOXA11 expression (31±15.3 months) compared to the prognoses in thosewith low HOXA11 expression (18±7.3 months, p=0.03). When HOXA11 was suppressed in the GBM cell lines, the anticancer effect of radiotherapy and/or temozolomide declined. In addition, five candidate mediators (TGFBR2, CRIM1, TXNIP, DPYSL2, and CRMP1) that may confer an oncologic effect after HOXA11 suppression were identified. CONCLUSION: The treatment resistance induced by the underexpression of HOXA11 can contribute to a poor prognosis in GBM. Further investigation will be needed to confirm the value of HOXA11 as a potential target for overcoming the treatment resistance by developing chemo- or radiosensitizers.

The Aurora kinase A inhibitor TC-A2317 disrupts mitotic progression and inhibits cancer cell proliferation.

Mitotic progression is crucial for the maintenance of chromosomal stability. A proper progression is ensured by the activities of multiple kinases. One of these enzymes, the serine/threonine kinase Aurora A, is required for proper mitosis through the regulation of centrosome and spindle assembly. In this study, we functionally characterized a newly developed Aurora kinase A inhibitor, TC-A2317. In human lung cancer cells, TC-A2317 slowed proliferation by causing aberrant formation of centrosome and microtubule spindles and prolonging the duration of mitosis. Abnormal mitotic progression led to accumulation of cells containing micronuclei or multinuclei. Furthermore, TC-A2317-treated cells underwent apoptosis, autophagy or senescence depending on cell type. In addition, TC-A2317 inactivated the spindle assembly checkpoint triggered by paclitaxel, thereby exacerbating mitotic catastrophe. Consistent with this, the expression level of Aurora A in tumors was inversely correlated with survival in lung cancer patients. Collectively, these data suggest that inhibition of Aurora kinase A using TC-A2317 is a promising target for anti-cancer therapeutics.

Zingerone suppresses angiogenesis via inhibition of matrix metalloproteinases during tumor development.

Angiogenesis is an essential step for tumor survival and progression, and the inhibition of angiogenesis is a good strategy for tumor therapeutics. In this study, we investigated the therapeutic effect of zingerone in a mouse tumor model. Zingerone suppressed tumor progression and tumor angiogenesis. Moreover, we found that zingerone inhibited the angiogenic activities of endothelial cells by both direct and indirect means. A mechanistic study showed that the activities of MMP-2 and MMP-9 in tumor cells were decreased by treatment with zingerone. Interestingly, zingerone-mediated inhibition of MMP-2 and MMP-9 was involved in the JNK pathway. In conclusion, zingerone showed strong anti-angiogenic activity via the inhibition of MMP-2 and MMP-9 during tumor progression, suggesting that zingerone may be a potential therapeutic drug for human cancers.