PURPOSE: The characteristic expression of DNA damage response proteins in familial breast cancers with BRCA1, BRCA2, or non-BRCA1/2 mutations has not been analyzed in Chinese patients. Our study aimed to assess the differential expression of microcephalin 1 (BRIT1), ATM serine/threonine kinase (ATM), checkpoint kinase 2 (CHEK2), BRCA1, RAD51 recombinase (RAD51), and poly (ADP-ribose) polymerase 1 (PARP-1) and establish the profile of Chinese familial breast cancers with different mutation status. METHODS: We constructed five tissue microarrays from 183 familial breast cancer patients (31 with BRCA1 mutations; 14 with BRCA2 mutations, and 138 with non-BRCA1/2 mutations). The DNA response and repair markers used for immunohistochemistry analysis included BRIT1, ATM, CHEK2, BRCA1, RAD51, and PARP-1. The expressions of these proteins were analyzed in BRCA1/2 mutated tumors. The association between pathologic characteristics with BRCA1/2 mutation status was also analyzed. RESULTS: In familial breast cancer patients, BRCA1 mutated tumors were more frequent with high nuclear grade, estrogen receptor/progesterone receptor/human epidermal growth factor receptor 2 negative, low Ki-67, and positive CK5/6. BRCA1 mutated tumors had lower CHEK2 and higher cytoplasmic BRIT1 expression than BRCA2 and non-BRCA1/2 mutation tumors. BRCA2-associated tumors showed higher CHEK2 and cytoplasmic RAD51 expression than those in other groups. Nuclear PARP-1 expression in BRCA1/2-associated tumors was significantly higher than in non-BRCA1/2 mutation tumors. Moreover, we found quite a few of negative PARP-1 expression cases in BRCA1/2 mutated groups. CONCLUSION: The clinicopathologic findings of BRCA1-associated Chinese familial breast cancers were similar to the results of other studies. Chinese familial breast cancer patients with BRCA1/2 mutations might have distinctive expression of different DNA damage response proteins. The reduced expression of PARP-1 in Chinese BRCA1/2 mutated breast cancer patients could influence the therapeutic outcome of PARP-1 inhibitors.
Asian Continental Ancestry Group* ; Breast Neoplasms* ; Breast* ; Checkpoint Kinase 2 ; Cytoplasm ; DNA Damage* ; DNA Repair ; DNA* ; Estrogens ; Genes, BRCA1 ; Genes, BRCA2 ; Humans ; Immunohistochemistry ; Phosphotransferases ; Rad51 Recombinase ; Receptor, Epidermal Growth Factor

Objective: To study the correlation of the gene expressions of Chk1 and Chk2 with sperm concentration and motility. METHODS: According to sperm concentration and motility (percentage of progressively motile sperm), we divided 80 semen samples into four groups of equal number: normal control, oligozoospermia (OS), asthenospermia (AS), and oligoasthenozoospermia (OAS). We detected the sperm DNA fragmentation index (DFI) and viability and determined the expressions of Chk1 and Chk2 in the sperm by RT-PCR and Western blot. RESULTS: Statistically significant differences were not found in sperm DFI among the control, OS, AS, and OAS groups (21.24±6.93, 19.67±7.64, 21.52±6.92, and 19.28±11.55, P>0.05), but observed in sperm concentration, progressive motility, and viability between the DFI >30% and DFI ≤30% groups (P<0.01). Compared with the normal control, sperm viability was remarkably decreased in the OS, AS, and OAS groups (［83.48±9.87］% vs ［63.86±9.16］%, ［50.45±16.99］%, and ［39.21±15.74］%, P<0.05). RT-PCR showed remarkable differences among the control, OS, AS, and OAS groups in the relative expression level of Chk1 mRNA (0.73±0.22, 0.62±0.14, 1.03±0.39, and 0.92±0.071, P<0.01), which was correlated positively with sperm concentration (b = 80.661, P<0.01) but negatively with sperm motility (b = －19.275, P < 0.01), as well as in that of Chk2 mRNA (0.66±0.30, 0.27±0.09, 0.59±0.19, and 0.42 ± 0.11, P<0.01), which was correlated negatively with sperm concentration (b = －90.809, P<0.01) but positively with sperm motility (b = 27.507, P <0.01). The relative expression levels of the Chk1 protein were significantly different among the four groups (0.63±0.05, 0.42±0.03, 1.13±0.08, and 0.87±0.07, P<0.01), which was correlated positively with sperm concentration (b = 55.74, P<0.01) but negatively with sperm motility (b =－22.649, P<0.01), and so were those of the Chk2 protein (1.23±0.36, 0.37±0.16, 0.87±0.08, and 0.68±0.12, P<0.01), which was correlated negatively with sperm concentration (b =－53.001, P<0.01) but positively with sperm motility (b = 16.676, P < 0.01). CONCLUSIONS Chk1 and Chk2 are significantly expressed in human sperm. In case of sperm DNA damage, up-regulated Chk1 expression may enhance sperm apoptosis and lead to asthenospermia, while increased Chk2 expression may inhibit spermatogenesis and result in oligospermia.
Apoptosis ; Asthenozoospermia ; genetics ; Checkpoint Kinase 1 ; genetics ; metabolism ; Checkpoint Kinase 2 ; genetics ; metabolism ; DNA Damage ; DNA Fragmentation ; Gene Expression ; Humans ; Male ; Oligospermia ; genetics ; Semen Analysis ; Sperm Count ; Sperm Motility ; genetics ; Spermatozoa ; physiology

BACKGROUNDCaffeine suppresses ataxia telangiectasia and Rad3 related and ataxia telangiectasia mutated (ATM) activities; ATM is the major kinase for DNA damage detection. This study aimed to investigate the effects of caffeine on DNA damage responses in cells from the bladder cancer cell line RT4 those were exposed to ionizing radiation (IR).

METHODSImmunofluorescent staining was performed to investigate changes in the proteins involved in DNA damage responses with or without caffeine. A mouse xenograft model was used to study the effects of caffeine on the DNA damage responses. Western blotting was used to investigate the effects of caffeine pretreatment on the ATM-Chk2-p53-Puma axis, while real-time polymerase chain reaction (RT-PCR) assessed changes in messenger RNA levels of p53 and downstream targets responding to IR. Finally, terminal deoxynucleotidyl transferase-dUTP nick end labeling assay. Western blotting and colony formation assay were used to measure the effects of caffeine on radiation-related apoptosis. All of the data were analyzed with a two-tailed Student's t-test.

RESULTSImmunofluorescent staining showed that caffeine pretreatment profoundly suppressed the formation of γH2AXand p53-binding protein 1 foci in RT4 cells in response to irradiation. Cellular and animal experiments suggested that this suppression was mediated by suppression of the ATM-Chk2-p53-Puma DNA damage-signaling axis. RT-PCR indicated caffeine also attenuated transactivation of p53 and p53-inducible genes. The colony formation assay revealed that caffeine displayed radioprotective effects on RT4 cells in response to low-dose radiation compared to the radiosensitization effects on T24 cells.

CONCLUSIONCaffeine may inhibit IR-related apoptosis of bladder cancer RT4 cells by suppressing activation of the ATM-Chk2-p53-Puma axis.

Animals ; Apoptosis ; drug effects ; radiation effects ; Caffeine ; pharmacology ; Cell Cycle Proteins ; metabolism ; Cell Line, Tumor ; Checkpoint Kinase 2 ; metabolism ; Humans ; Immunohistochemistry ; Male ; Mice ; Mice, Nude ; Radiation, Ionizing ; Real-Time Polymerase Chain Reaction ; Signal Transduction ; drug effects ; Tumor Suppressor Protein p53 ; metabolism ; Urinary Bladder Neoplasms ; radiotherapy

Biomarker identification is crucial for the selection of patients who might benefit from radiotherapy. To explore potential markers for response and prognosis in patients with locally advanced esophageal carcinoma treated with radiotherapy followed by surgery, we evaluated the expression of cell cycle checkpoint-related proteins Chk2, Cdc25C, and Cyclin D1. A total of 56 patients with locally advanced esophageal squamous cell carcinoma were treated with radiotherapy followed by surgery. Pretreatment tumor biopsy specimens were analyzed for Chk2, Cdc25C, and Cyclin D1 expression by immunohistochemistry. High expression of Chk2, Cyclin D1, and Cdc25C was observed in 44 (78.6%), 15 (26.8%), and 27 (48.2%) patients, respectively. The median survival was 16 months (range, 3-154 months), with a 5-year overall survival rate of 19.6%. Overexpression of Chk2 was associated with smoking (P = 0.021), overexpression of Cdc25C was associated with patient age (P = 0.033) and tumor length (P = 0.001), and overexpression of Cdc25C was associated with pathologic complete response (P = 0.038). Univariate analysis demonstrated that overexpression of Cdc25C and pathologic complete response was associated with better survival. In multivariate analysis, Cdc25C was the most significant independent predictor of better survival (P = 0.014) for patients treated with radiotherapy followed by surgery. Overexpression of Cdc25C was significantly associated with pathologic complete response and better survival of patients with locally advanced esophageal cancer treated with radiotherapy followed by surgery. These results suggest that Cdc25C may be a biomarker of treatment response and good prognosis for esophageal carcinoma patients. Thus, immunohistochemical staining of Cdc25C in a pretreatment specimen may be a useful method of identifying optimal treatment for patients with esophageal carcinoma.
Adult ; Aged ; Carcinoma, Squamous Cell ; metabolism ; pathology ; radiotherapy ; surgery ; Checkpoint Kinase 2 ; metabolism ; Combined Modality Therapy ; Cyclin D1 ; metabolism ; Esophageal Neoplasms ; metabolism ; pathology ; radiotherapy ; surgery ; Female ; Follow-Up Studies ; Humans ; Male ; Middle Aged ; Neoplasm Staging ; Particle Accelerators ; Proportional Hazards Models ; Smoking ; Survival Rate ; cdc25 Phosphatases ; metabolism

Ataxia Telangiectasia Mutated Proteins ; Breast ; metabolism ; pathology ; Breast Neoplasms ; metabolism ; pathology ; Carcinoma, Ductal, Breast ; metabolism ; pathology ; Carcinoma, Intraductal, Noninfiltrating ; metabolism ; pathology ; Cell Cycle Proteins ; metabolism ; Checkpoint Kinase 2 ; DNA-Binding Proteins ; metabolism ; Female ; Humans ; Lymphatic Metastasis ; Neoplasm Grading ; Protein-Serine-Threonine Kinases ; metabolism ; Tumor Burden ; Tumor Suppressor Protein p53 ; metabolism ; Tumor Suppressor Proteins ; metabolism

To explore the role of the Chk2 protein expression and DNA double strand breaks (DSBs) repair in low dose hyper-radiosensitivity (HRS)/increased radioresistance (IRR) of non-small cell lung cancer, A549 cells were subjected to irradiation at the dosage ranging from 0.05-2 Gy. Clonogenic survival was measured by using fluorescence-activated cell sorting (FACS) plating technique. Percentage of cells in M-phase after low doses of X-irradiation was evaluated by phospho-histone H3-FITC/PI and Western blotting was used to detect protein expression of Chk2 and phospo-Chk2. DNA DSBs repair efficiency was also measured by induction and persistence of γ-H2AX. The results showed that the killing ability of irradiation with A549 cells increased at low conditioning dose below 0.3 Gy. Within the dose of 0.3 to 0.5 Gy, A549 cells showed a certain extent of radiation resistance. And when the dose was more than 0.5 Gy, survival fraction exhibited a negative correlation with the dosage. There was no difference between the 0.1 or 0.2 Gy dosage groups and the un-irradiated group in terms of the percentage of cells in M phase. But in the high dosage group (0.3-1.0 Gy), the percentage of cells in M phase was decreased markedly. In addition, the percentage of cells in M phase began to decrease two hours after irradiation. One hour after irradiation, there was no conspicuous activation of Chk2 kinase in 0.1 or 0.2 Gy group, but when the irradiation dose reached 0.3 Gy or higher, Chk2 kinase started to be activated and the activation level showed no significant difference among high dosage groups (0.4, 0.5, 1.0 Gy). Within 1 to 6 h, the DNA DSBs repair efficiency was decreased at 0.2 Gy but increased at 0.5 Gy and 1.0 Gy, which was in line with Chk2 activation. We are led to conclude that the mechanism of HRS/IRR in A549 cell line was probably due to early G(2)/M checkpoint arrest and enhanced DNA DSBs repair. In this regard, Chk2 activation plays a key role in G(2)/M checkpoint activation.
Adenocarcinoma ; genetics ; metabolism ; Cell Line, Tumor ; Checkpoint Kinase 2 ; genetics ; metabolism ; DNA Damage ; genetics ; DNA Repair ; genetics ; Humans ; Lung Neoplasms ; genetics ; metabolism ; Radiation Tolerance ; genetics

OBJECTIVETo explore the increasing effect of blocking Chk1 and /or Chk2 gene by Chk1 or Chk2-specific antisense oligodeoxynucleotides (AsODN) on apoptosis in HeLa cell line after irradiation and its mechanism of action.

METHODSAsynchronized HeLa cells were exposed to (60)Co-irradiation at different dosage to activate G(2)/M checkpoint arrest. The cell cycle profiles were observed in HeLa cells after irradiation at a range of various doses and different time points by flow cytometry. In the experimental groups, Chk1/2 sODN and AsODN alone or in combination were transfected into HeLa cells, and the cells were exposed to (60)Co-irradiation at 24 h after transfection. The changes of Chk1/2 protein expression were assayed by Western blot and confocal laser scanning microscopy (Confocal), and the cell cycles, apoptosis rates and cell cycle specific apoptosis were detected by annexin V-PI labeling and flow cytometry.

RESULTSApoptotic response was significantly increased in the Hela cells after G(2)/M arrest and was inversed to activation of G(2)/M checkpoint. Either Chk1 or Chk2-specific AsODN consistently enhanced DNA damage-induced apoptosis by 90% approximately 120%, compared to corresponding sODN control (P < 0.05). Unexpectedly, combined use of Chk1- and Chk2-specific AsODN did not produce synergistic effect as compared to treatment with Chk1- or Chk2-specific AsODN alone (P > 0.05). While irradiated HeLa cells underwent apoptosis preferentially in G(1)-phase, apoptosis occurred in either of G(1)-, S- or G(2)/M -phase in the presence of Chk1 and/or Chk2 AsODN.

CONCLUSIONThe radioresistance is mainly induced by activating the cell cycle checkpoint signal transduction pathway after irradiation, and abrogating of the key effector Chk1 and Chk2 may increase the apoptotic sensitivity to irradiation due to changes of the pattern of cell cycle specific apoptosis.

Apoptosis ; radiation effects ; Cell Cycle ; radiation effects ; Checkpoint Kinase 1 ; Checkpoint Kinase 2 ; Cobalt Radioisotopes ; Down-Regulation ; Gene Expression Regulation, Neoplastic ; HeLa Cells ; Humans ; Oligodeoxyribonucleotides, Antisense ; genetics ; Protein Kinases ; genetics ; metabolism ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; Transfection

OBJECTIVETo investigate the changes in cell cycle induced by cisplatin (DDP) and the effect of antisense oligonucleotide (AsODN) targeting Chk1/2 on DDP-induced apoptosis in lung cancer cell line A549 cells.

METHODSThe characteristics of cell cycle and apoptosis induced by DDP were detected by flow cytometry using SubG1 method. Chk1/2 mRNA and protein expression were assayed by RT-PCR and Western blot under best condition of transfection of AsODN targeting Chk1/2 by lipofection. Apoptosis of A549 cells induced by DDP was determined by flow cytometry using AnnexinV-FITC staining after transfection of Chk1/2 AsODN.

RESULTSAsynchronized A549 cells were treated with 10 micromol/L DDP, and significant S-phase arrest was observed at 12 h later. Transfection with antisense oligonucleotide targeting Chk1/2 inhibited the Chk1/2 expression at both mRNA and protein levels. Either Chk1 or Chk2-specific AsODN consistently enhanced DNA damage-induced apoptosis by 100% - 200%, compared with that in the sODN control (P < 0.05), but combined use of Chk1- and Chk2-specific AsODN did not show synergistic effects as compared with that induced by treatment with Chk1- or Chk2-specific AsODN alone (P > 0.05).

CONCLUSIONChk1 and Chk2 may be regarded as effective targets of chemotherapy for lung cancer. Silencing the key effector Chk1 and Chk2 genes may significantly increase the chemosensitivity of lung cancer cells.

Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Cell Cycle ; drug effects ; Cell Line, Tumor ; Checkpoint Kinase 1 ; Checkpoint Kinase 2 ; Cisplatin ; pharmacology ; Gene Silencing ; Humans ; Lung Neoplasms ; metabolism ; pathology ; Oligonucleotides, Antisense ; genetics ; Protein Kinases ; genetics ; metabolism ; Protein-Serine-Threonine Kinases ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Transfection

BACKGROUNDCheckpoint kinase 2 (CHK2) is a DNA damage-activated protein kinase which is involved in cell cycle checkpoint control. CHK2 gene could be a candidate gene for colorectal cancer susceptibility. But there are few systematic reports on mutation of CHK2 in colorectal cancer.

METHODSThe mutations of all 14 exons of CHK2 in 56 colorectal cancer cell lines were screened systematically, using denaturing high-performance liquid chromatography (DHPLC) to screen the mismatches of the CHK2 exons amplified products, and then the suspected mutant cell lines were scanned by nucleotide sequence analysis.

RESULTSVACO400 in CHK2 exon 1a was suspected to have mutation by DHPLC and confirmed by sequence, but this was nonsense mutation. C106, CX-1, HT-29, SK01, SW480, SW620 and VACO400 in CHK2 exon 1b were confirmed to have the same nonsense mutation in 11609 A > G. DLD-1 and HCT-15 in CHK2 exon 2 were confirmed to have missense mutation R145W, which was heterozygous C > T missense mutation at nucleotide 433, leading to an Arg > Trp substitution within the FHA domain.

CONCLUSIONSThe CHK2 mutation in colorectal cancer is a low frequency event. There are just 10 cell lines to have sequence variations in all the 14 exons in 56 colorectal cancer cell lines and only DLD-1/HCT-15 had heterozygous missense mutation. These findings may give useful information of susceptibility of colorectal cancer as single nucleotide polymorphysim.

Cell Line, Tumor ; Checkpoint Kinase 2 ; Chromatography, High Pressure Liquid ; Colorectal Neoplasms ; genetics ; DNA Damage ; Humans ; Mutation ; Protein-Serine-Threonine Kinases ; genetics

OBJECTIVETo investigate the prevalence of CHEK2 c.1100delC mutation among non-BRCA1/BRCA2 familial/early-onset breast cancer patients in Shanghai.

METHODSOne hundred and fourteen non-BRCA1/BRCA2 hereditary breast cancer patients were analyzed, among whom 76 cases had at least one first-degree relative affected with breast cancer and 38 cases were diagnosed as breast cancer below the age of 40 years without family history. The mutation genotyping of CHEK2 c.1100delC were carried out through long-range PCR amplifying of exons 10-14, and followed by amplification of exon 10 and then DNA direct sequencing.

RESULTSNo c.1100delC frame-shift mutation was identified in our studied population. One novel missense mutation 1111C>T (p.His371Tyr), located in kinase catalytic domain, was found in 3 familial breast cancer cases but no one in control group.

CONCLUSIONCHEK2 c.1100delC is rare variant for Chinese population and may not contribute to predisposition for hereditary breast cancer in Shanghai. Novel variant -1111C>T could be in association with genetic susceptibility to breast cancer. A further study is needed to confirm the results.

Adult ; Aged ; Apoptosis Regulatory Proteins ; Asian Continental Ancestry Group ; genetics ; BRCA1 Protein ; genetics ; BRCA2 Protein ; genetics ; Base Sequence ; Breast Neoplasms ; ethnology ; genetics ; Checkpoint Kinase 2 ; China ; DNA Mutational Analysis ; Female ; Frameshift Mutation ; Genetic Predisposition to Disease ; genetics ; Humans ; Middle Aged ; Mutation, Missense ; Protein-Serine-Threonine Kinases ; genetics ; Sequence Deletion ; Young Adult