Progress in the Study of Spindle Assembly Checkpoint in Lung Cancer / 中国肺癌杂志

Spindle assembly checkpoint (SAC) is a protective mechanism for cells to undergo accurate mitosis. SAC prevented chromosome segregation when kinetochores were not, or incorrectly attached to microtubules in the anaphase of mitosis, thus avoiding aneuploid chromosomes in daughter cells. Aneuploidy and altered expression of SAC component proteins are common in different cancers, including lung cancer. Therefore, SAC is a potential new target for lung cancer therapy. Five small molecule inhibitors of monopolar spindle 1 (MPS1), an upstream component protein of SAC, have entered clinical trials. This article introduces the biological functions of SAC, summarizes the abnormal expression of SAC component proteins in various cancers and the research progress of MPS1 inhibitors, and expects to provide a reference for the future development of lung cancer therapeutic strategies targeting SAC components.
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Spindle assembly checkpoint complex-related genes TTK and MAD2L1 are over-expressed in lung adenocarcinoma: a big data and bioinformatics analysis / 南方医科大学学报

OBJECTIVE@#To screen the key genes related to the prognosis of lung adenocarcinoma through big data analysis and explore their clinical value and potential mechanism.@*METHODS@#We analyzed GSE18842, GSE27262, and GSE33532 gene expression profile data obtained from the Gene Expression Omnibus (GEO). Bioinformatics methods were used to screen the differentially expressed genes in lung adenocarcinoma tissues and KEGG and GO enrichment analysis was performed, followed by PPI interaction network analysis, module analysis, differential expression analysis, and prognosis analysis. The expressions of MAD2L1 and TTK by immunohistochemistry were verified in 35 non-small cell lung cancer specimens and paired adjacent tissues.@*RESULTS@#We identified a total of 256 genes that showed significant differential expressions in lung adenocarcinoma, including 66 up-regulated and 190 down-regulated genes. Thirty-two up-regulated core genes were screened by functional analysis, and among them 29 were shown to significantly correlate with a poor prognosis of patients with lung adenocarcinoma. All the 29 genes were highly expressed in lung adenocarcinoma tissues compared with normal lung tissues and were mainly enriched in cell cycle pathways. Seven of these key genes were closely related to the spindle assembly checkpoint (SAC) complex and responsible for regulating cell behavior in G2/M phase. We selected SAC-related proteins TTK and MAD2L1 to test their expressions in clinical tumor samples, and detected their overexpression in lung adenocarcinoma tissues as compared with the adjacent tissues.@*CONCLUSIONS@#Seven SAC complex-related genes, including TTK and MAD2L1, are overexpressed in lung adenocarcinoma tissues with close correlation with the prognosis of the patients.

Efectos adversos inmunomediados por inhibidores de PD-1 / PD-1 inhibitors immune-mediated side effects

Los anticuerpos monoclonales que inhiben los puntos de control PD-1 y CTLA-4 se usan actualmente en el tratamiento del melanoma y cáncer metastásico de pulmón de células no pequeñas, entre otros. Se refiere el caso de una paciente con cáncer de pulmón en tratamiento con pembrolizumab. La paciente se presentó con edema facial y parálisis facial periférica. En el laboratorio se observó la hormona tirotrofina (TSH) elevada y se llegó al diagnóstico de hipotiroidismo por pembrolizumab. Inició tratamiento con levotiroxina con mejoría clínica. Se presenta este caso por el importante papel del dermatólogo en el manejo multidisciplinario del paciente oncológico. (AU)

Monoclonal antibodies that inhibit PD-1 and CTLA-4 control points are currently used in the treatment of melanoma and metastatic non-small cell lung cancer, among others. The case of a patient, with lung cancer being treated with Pembrolizumab. The patient was presented with facial edema and peripheral facial paralysis and in the laboratory the elevated hormone Tyrotrophin (TSH) was observed, the diagnosis of pembrolizumab hypothyroidism was reached. She started treatment with levothyroxine with clinical improvement. This case is presented by the important role of the dermatologist in the multidisciplinary management of the cancer patient. (AU)

Downregulation of MCL-1 by Diallyl Disulfide Induces G/M Arrest in Human Leukemia K562 Cells and Its Mechanism / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the inducing effect of down-regulation of MCL-1 by diallyl disulfide(DADS) on the G/M arrest of human leukemia K562 cells and its mechanisms.</p><p><b>METHODS</b>CCK-8 was used to detect the effect of DADS on proliferation of K562 cells, flow cytometry was employed to observe the effect of cycle arrest by DADS and RNAi silencing MCL-1 gene in K562 cells. The expressions of MCL-1, PCNA and CDK1 in K562 cells treated with DADS were detected by Western blot. The amphigamy of MCL-1 with PCNA and CDK1 was detected by Coimmunoprecipitation.</p><p><b>RESULTS</b>CCK-8 detection showed that the inhibition rates of K562 cells treated with 15, 30, 60, 120, 240 µmol/L DADS were 32.48%, 59.34%, 66.42%, 77.06%, 81.05% respectively (P<0.05). Flow cytometry analysis revealed that the perecentages of G/M cells were increased to 18.6% and 34.4%, 17.5% and 28.5%, respectively at 24 and 48 h after treating K562 cells with 60 and 120 µmol/L DADS (P<0.05). And the perecentage of G/M cells of silencing MCL-1 was significantly increased (P<0.05). Silencing effects of MCL-1+DADS on the cells were enhanced more significantly as compared with DADS or MCL-1 alone (P<0.05). Western blot exhibited that DADS could markedly downregulate the expression of MCL-1, PCNA and CDK1(P<0.05). Coimmunoprecipitation revealed that MCL-1 bound with PCNA and CDK1, then forming heterodimers, which were downregulated respectively more significantly than that in the control group after treating K562 cells with DADS for 8 h (P<0.05).</p><p><b>CONCLUSION</b>DADS can inhibit the K562 cell proliferation and induce them arrest G/M through downregulation of MCL-1, then decreasing the expression of PCNA and CDK1 in hunan leukemia K562 cells. Moreover, silencing MCL-1 can enhance the effect of DADS.</p>

Ophiopogonin D inhibits cell proliferation, causes cell cycle arrest at G2/M, and induces apoptosis in human breast carcinoma MCF-7 cells / 中西医结合学报

<p><b>OBJECTIVE</b>To investigate the effects of ophiopogonin D on human breast cancer MCF-7 cells.</p><p><b>METHODS</b>Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation experiments. Cell cycle was measured with cell cycle flow cytometry and a living cell assay. Apoptosis and terminal deoxynucleoitidyl transferase-mediated dUTP nick end labeling assays were performed to detect the apoptosis of MCF-7 cells induced by ophiopogonin D. Finally, Western blotting was used to explore the mechanism.</p><p><b>RESULTS</b>Exposure of cells to ophiopogonin D resulted in marked decreases in viable cells and colony formation with a dose-dependent manner. Treatment of these cells with ophiopogonin D also resulted in cell cycle arrest at the G(2)/M phase, and increased apoptosis. Mechanistically, ophiopogonin D-induced G(2)/M cell cycle arrest was associated with down-regulation of cyclin B1. Furthermore, activation of caspase-8 and caspase-9 was involved in ophiopogonin D-induced apoptosis.</p><p><b>CONCLUSION</b>The data suggested that ophiopogonin D inhibits MCF-7 cell growth via the induction of cell cycle arrest at the G(2)/M phase.</p>

The p90 ribosomal S6 kinase 2 specifically affects mitotic progression by regulating the basal level, distribution and stability of mitotic spindles

RSK2, also known as RPS6KA3 (ribosomal protein S6 kinase, 90 kDa, polypeptide 3), is a downstream kinase of the mitogen-activated protein kinase (MAPK) pathway, which is important in regulating survival, transcription, growth and proliferation. However, its biological role in mitotic progression is not well understood. In this study, we examined the potential involvement of RSK2 in the regulation of mitotic progression. Interestingly, depletion of RSK2, but not RSK1, caused the accumulation of mitotic cells. Time-lapse analysis revealed that mitotic duration, particularly the duration for metaphase-to-anaphase transition was prolonged in RSK2-depleted cells, suggesting activation of spindle assembly checkpoint (SAC). Indeed, more BubR1 (Bub1-related kinase) was present on metaphase plate kinetochores in RSK2-depleted cells, and depletion of BubR1 abolished the mitotic accumulation caused by RSK2 depletion, confirming BubR1-dependent SAC activation. Along with the shortening of inter-kinetochore distance, these data suggested that weakening of the tension across sister kinetochores by RSK2 depletion led to the activation of SAC. To test this, we analyzed the RSK2 effects on the stability of kinetochore–microtubule interactions, and found that RSK2-depleted cells formed less kinetochore–microtubule fibers. Moreover, RSK2 depletion resulted in the decrease of basal level of microtubule as well as an irregular distribution of mitotic spindles, which might lead to observed several mitotic progression defects such as increase in unaligned chromosomes, defects in chromosome congression and a decrease in pole-to-pole distance in these cells. Taken together, our data reveal that RSK2 affects mitotic progression by regulating the distribution, basal level and the stability of mitotic spindles.

Oleanolic acid induces G₂/M phase arrest and apoptosis in human hepatocellular carcinoma Bel-7402 cells / 中国中药杂志

This study was to examine the mechanism of oleanolic acid (OA) induces G2/M phase arrest and apoptosis in human hepatocellular carcinoma Bel-7402 cells. MTT and trypan blue exclusion test assay were adopted to detect the proliferate status of cells treated with OA. We assayed the cell cycle by flow cytometry using PI staining. Apoptosis was determined by Annexin V-FITC staining and PI labeling. The expressions of cycle related proteins and apoptotic related proteins were determined by Western blot analysis. OA strongly inhibited human hepatoma cells proliferation. When Bel-7402 cells were pretreated with OA for 24 h, OA induced apoptosis and G₂/M phase cell cycle arrest in a concentration-dependent manner. Analysis of the cell cycle regulatory proteins demonstrated that OA decreased the protein levels of cyclin B1, but increased the protein levels of p-Cdk1 (Tyr15) and p-Cdc25C (Ser 216). Moreover, OA modulated the phosphorylation of protein kinases Chk1 and p2l. Western blotting assay also showed significant decrease of Bcl-2 protein expression and increase of Bax protein expression, the cytosol Cyt c level, cleaved-caspase-9 and cleaved-caspase-3 activity. These data suggest that OA produces anti-tumor effect via induction of G₂/M cell cycle arrest and apoptosis.

Partial Hepatectomy in Acetylation-Deficient BubR1 Mice Corroborates that Chromosome Missegregation Initiates Tumorigenesis

BACKGROUND: Aneuploidy has been suggested as one of the major causes of cancer from the time of Boveri. In support of this notion, many studies have shown that cancer cells exhibit aneuploidy. However, there are evidences that do not support the aneuploidy hypothesis. We have previously reported that the spindle assembly checkpoint protein BubR1 is acetylated in mitosis and that the acetylation of BubR1 is crucial for checkpoint maintenance and chromosome-spindle attachment. Mice heterozygous for acetylation-deficient BubR1 (K243R/+) spontaneously develop cancer with chromosome instability. As K243R/+ mice develop hepatocellular carcinoma, we set out to test if chromosome mis-segregation was the cause of their liver cancer. METHODS: Primary hepatocytes in the regenerating liver after partial hepatectomy (PH) were analyzed and compared for various mitotic parameters. RESULTS: Primary hepatocytes isolated from K243R/+ mice after PH displayed a marked increase of chromosome misalignment, accompanied by an increase of micronuclei. In comparison, the number of nuclei per cell and the centrosome numbers were not different between wild-type and K243R/+ mice. Taken together, chromosome mis-segregation provokes tumorigenesis in mouse liver. CONCLUSION: Our results corroborate that PH provides a reliable tool for assessing mitotic infidelity and cancer in mice.

The ethanol extract isolated from Weiqi Decoction induces G₂/M arrest and apoptosis in AGS cells / 中国结合医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of the ethanol extract isolated from Weiqi Decoction (WQD-EE) on AGS cell proliferation and apoptosis.</p><p><b>METHODS</b>By using high-performance liquid chromatography with ultraviolet detectors (HPLC-UV) assay and MTT method, the main compounds in WQD-EE and cell viability were detected. And cell cycle distributions were determined by flow cytometry with propidium iodine (PI) staining while apoptosis was detected by flow cytometry with annexin V/PI double staining. Finally, caspase-3 activities were measured by colorimetric method and protein expression was determined by Western blotting.</p><p><b>RESULTS</b>HPLC analysis showed that naringin (35.92 μg/mg), nobiletin (21.98 μg/mg), neohesperidin (17.98 μg/mg) and tangeretin (0.756 μg/mg) may be the main compounds in WQD-EE. WQD-EE not only inhibited AGS and MCF 7 cell proliferation in a dose-dependent manner, but also blocked cell cycle progression at G2/M stage as well as inducing cell apoptosis at concentrations triggering significant inhibition of proliferation and cell cycle arrest in AGS cells. While at 0.5 mg/mL, WQD-EE significantly increased caspase-3 activity by 2.75 and 7.47 times at 24 h and 48 h, respectively. Moreover, WQD-EE in one hand reduced protein expressions of p53 and cyclin B1, and in other hand enhanced protein expressions of cytochrome c and Bax. Protein levels of Bcl-2, Fas L and Fas were not significantly affected by WQD-EE.</p><p><b>CONCLUSIONS</b>WQD-EE inhibits AGS cell proliferation through G2/M arrest due to down-regulation of cyclin B1 protein expression, and promotes apoptosis by caspase-3 and mitochondria-dependent pathways, but not by p53-dependent pathway.</p>

Knockdown of Bcl-xL Enhances Growth-Inhibiting and Apoptosis-Inducing Effects of Resveratrol and Clofarabine in Malignant Mesothelioma H-2452 Cells

Mcl-1 and Bcl-xL, key anti-apoptotic proteins of the Bcl-2 family, have attracted attention as important molecules in the cell survival and drug resistance. In this study, we investigated whether inhibition of Bcl-xL influences cell growth and apoptosis against simultaneous treatment of resveratrol and clofarabine in the human malignant mesothelioma H-2452 cells. Resveratrol and clofarabine decreased Mcl-1 protein levels but had little effect on Bcl-xL levels. In the presence of two compounds, any detectable change in the Mcl-1 mRNA levels was not observed in RT-PCR analysis, whereas pretreatment with the proteasome inhibitor MG132 led to its accumulation to levels far above basal levels. The knockdown of Bcl-xL inhibited cell proliferation with cell accumulation at G2/M phase and the appearance of sub-G0/G1 peak in DNA flow cytometric assay. The suppression of cell growth was accompanied by an increase in the caspase-3/7 activity with the resultant cleavages of procaspase-3 and its substrate poly (ADP-ribose) polymerase, and increased percentage of apoptotic propensities in annexin V binding assay. Collectively, our data represent that the efficacy of resveratrol and clofarabine for apoptosis induction was substantially enhanced by Bcl-xL-lowering strategy in which the simultaneous targeting of Mcl-1 and Bcl-xL could be a more effective strategy for treating malignant mesothelioma.

Triptolide induces apoptosis through extrinsic and intrinsic pathways in human osteosarcoma U2OS cells.

Triptolide, a diterpene derived from Tripterygium wilfordii Hook f., a Chinese medicinal herb, has been reported to inhibit cell proliferation and induce apoptosis in various human cancer cells, but its anticancer effects on human osteosarcoma cells have not yet been elucidated. In this study, we investigated whether triptolide induces apoptosis in human osteosarcoma cells and the underlying molecular mechanisms. We firstly demonstrated that triptolide inhibited cell growth and induced apoptosis in U2OS cells. Western blot analysis showed that the levels of procaspase-8, -9, Bcl-2, Bid and mitochondrial cytochrome c were downregulated in triptolide-treated U2OS cells, whereas the levels of Fas, FasL, Bax, cytosolic cytochrome c, cleaved caspase-3 and cleaved PARP were upregulated. These results suggest that triptolide induces apoptosis in U2OS cells by activating both death receptor and mitochondrial apoptotic pathways.

MAD2 Expression in Ovarian Carcinoma: Different Expression Patterns and Levels among Various Types of Ovarian Carcinoma and Its Prognostic Significance in High-Grade Serous Carcinoma

BACKGROUND: Mitotic arrest deficiency protein 2 (MAD2) is a key component of spindle assembly checkpoint function, which mediates cell apoptosis through microtubule kinetics. Aberrant expression of MAD2 is believed to be associated with the development of chromosome instability. MAD2 also has a signihicant role in cellular drug resistance to taxane chemotherapeutic agents. METHODS: Expression of MAD2 and p53 was investigated using immunohistochemistry in 85 cases of ovarian carcinomas. Clinicopathological data including progression-free survival were analyzed. RESULTS: A significant (p=.035) association was observed between the grade of serous carcinoma and the expression level of MAD2. While low-grade serous carcinoma showed a low-level expression of MAD2, high-grade serous carcinoma showed a high-level expression of MAD2. We also determined that low-level expression of MAD2 was associated with reduced progression-free survival (PFS) (p=.016) in high-grade serous carcinoma. CONCLUSIONS: MAD2 expression in ovarian carcinoma is related to the grade of serous carcinoma and PFS of high-grade serous carcinoma. Expression level of MAD2 detected by immunohistochemistry may serve as an indicator in predicting the response of microtubule-interfering chemotherapeutic agents.

Inhibitory Effect of Melanoma Differentiation Associated Gene-7/Interleukin-24 on Invasion In Vitro of Human Melanoma Cancer Cells

The acquisition of metastasis potential is a critical point for malignant tumors. Melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24) is a potential tumor suppress gene and frequently down-regulated in malignant tumors. It has been implicated that overexpression of MDA-7 led to proliferation inhibition in many types of human tumor. Invasion is an important process which is potential to promote tumor metastasis. However, the role and potential molecular mechanism of mda-7/IL-24 to inhibit the invasion of human melanoma cancer is not fully clear. In this report, we identified a solid role for mda-7/IL-24 in invasion inhibition of human melanoma cancer LiBr cells, including decreasing of adhesion and invasion in vitro, blocking cell cycle, down-regulating the expression of ICAM-1, MMP-2/9, CDK1, the phosphorylation of ERK and Akt, NF-kappaB and AP-1 transcription activity. Meanwhile, there was an increased expression of PTEN in mda-7/IL-24 over-expression LiBr cells. Our results demonstrated that mda-7/IL-24 is a potential invasion suppress gene, which inhibits the invasion of LiBr cells by the down-regulation of ICAM-1, MMP-2/9, PTEN, and CDK1 expression. The molecular pathways involved were the MAPK/ERK, PI3K-Akt, NF-kappaB, and AP-1. These findings suggest that mda-7/IL-24 may be used as a possible therapeutic strategy for human melanoma cancer.

CUEDC2: an emerging key player in inflammation and tumorigenesis

CUE domain-containing 2 (CUEDC2) is a protein involved in the regulation of the cell cycle, inflammation, and tumorigenesis and is highly expressed in many types of tumors. CUEDC2 is phosphorylated by Cdk1 during mitosis and promotes the release of anaphase-promoting complex or cyclosome (APC/C) from checkpoint inhibition. CUEDC2 is also known to interact with IkB kinase α (IKKα) and IKKβ and has an inhibitory role in the activation of transcription factor nuclear factor-κB. Moreover, CUEDC2 plays an important role in downregulating the expression of hormone receptors estrogen receptor-α and progesterone receptor, thereby impairing the responsiveness of breast cancer to endocrine therapies. In this review, current knowledge on the multi-functions of CUEDC2 in normal processes and tumorigenesis are discussed and summarized.

Mutational Analysis of TTK Gene in Gastric and Colorectal Cancers with Microsatellite Instability / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The TTK gene plays a crucial role in regulation of the mitotic checkpoint. The TTK gene has an A9 mononucleotide repeat in the coding sequences, which harbors mutations in gastric (GC) and colorectal cancers (CRC) with microsatellite instability (MSI). However, there are three more repeats (the A7s) in the coding sequences that have not been analyzed. The aim of this study was to explore whether the three A7s as well as the A9 are altered in GC and CRC, and to find any association of TTK mutation with clinocopathologic characteristics of GC and CRC. MATERIALS AND METHODS: We analyzed exon 5 (A7 and A7) and exon 22 (A9 and A7) which have repeat sequences in 30 GC with high MSI (MSI-H), 15 GC with low MSI (MSI-L), 35 CRC with MSI-H, and 15 CRC with MSI-L, by single-strand conformation polymorphism (SSCP) and DNA sequencing assays. RESULTS: Overall, we detected 23 frameshift mutations in the repeat sequences of TTK in the GC with MSI-H (11/30; 36.7%) and the CRC with MSI-H (12/35; 34.3%), but not in the cancers with MSI-L. The mutations were observed in both A9 and A7 of exon 22, but in neither of the two A7s of exon 5. The mutations consisted of c.2560delA, c.2560dupA, c.2571delA and c.[2560delA(+)2571delA]. All of the mutations were frameshift mutations and would result in premature stops of TTK protein synthesis. There was no significant difference in clinopathologic parameters of the cancers with the mutations. CONCLUSION: Our data indicate that frameshift mutations of TTK are common in both GC and CRC with MSI-H, and that the mutations occur not only in the A9 repeat but also in the A7 repeat. The data suggest that frameshift mutations of TTK might alter cell cycle control in the affected cells and contribute to pathogenesis of cancers with MSI-H.

THE ROLE OF REGULATED PROTEINS RELATED TO CELL CYCIE IN CARCINOGENESIS

The cell cycle is composed of G1, S, G2 and M phase. The transitions between different phases are regulated at checkpoint such as Start(restriction), S phase and mitotic checkpoint. These checkpoints are regulated by specific cyclins and Cdks(cyclin-dependent kinases). Especially, Start checkpoint in late G1 is though to be very important in control of cell cycle. In this study, it was shown various CDKN2(p16ink4A) alteration, including deletions, mutations, down regulations, and performed differential expression of p53, Cdk4, PCNA and pRb in stomach cancer tissues. 1. The frequency of CDKN2 mutations was not observed in the 19 primary stomach cancer tissues. In contrast to the mutations of CDKN2, mRNA levels was showed by Northern blot analysis that expression of CDKN2 was absent or decreased in 10 of the 19(53%) primary stomach adenocarcinoma. Western blot analysis was performed to determine the differential expression of p53, Cdk4, PCNA related to Start checkpoint. Overexpression of p53 was shown 38%, Cdk4 was expressed in all each specimens, and expression of PCNA was not shown. 2. As the other method to determine the differential expression of p53, Cdk4, PCNA and pRb, immunohistochemical analyses were performed on each 14 formalin-fixed and paraffin embedded tumor tissues of stomach adenocarcinoma. p53 overexpression was showed to clear nuclear staining only in tumor cells not in nonneoplastic cells. In staining for cdk4, the tumor was considered to be cdk4 positive if there was nuclear staining in tumor cells, regardless of cytoplasmic staining. PCNA staining for carcinoma tissues showed more intense nuclear staining in tumor cells than in nonneoplastic cells. pRb overexpression was show in tumor cells. Significant differences were observed in the expression of the proteins among the cancers from different anatomic site. Overexpression of adenocarcinomas had high rate of p53(57.1%) and pRb(71.4% ), and low late of cdk4(7.1% ) and PCNA(14.3% ), As these results, deletion of CDKN2 gene in human stomach cancer was not observed but mRNA expression was down regulated in restriction checkpoint, G1 phase. Inactivation of the CDKN2 gene due to hypermethylation may play an important role in development of cancer. And one of the abnormalities in p53, Cdk4, PCNA or pRb function occurs very common in various cancers, especially oral adenocarcinoma, osteosarcoma and squemous cell carcinoma, suggest that components in restriction checkpoint also play an critical role in the carcinogenesis and progression of cancers.