Association Between the Polymorphism of Aldehyde Dehydrogenase 2 Gene and Cerebral Infarction in a Hakka Population in Southern China.

Genetic factors play an important role in determining the susceptibility to ischemic stroke. Herein, we examined the association of an aldehyde dehydrogenase 2 (ALDH2) gene polymorphism with cerebral infarction. Patients with cerebral infarction (n = 963) and healthy controls (n = 921) were included. Genotyping was performed using gene chip platform analysis, and Sanger sequencing was used to confirm ALDH2 genotypes. The risk prediction of ALDH2 polymorphisms for cerebral infarction was examined under three genetic modes of inheritance. For males, ALDH2*2/*2 genotype was a significant risk factor for cerebral infarction in the co-dominant model (age-, smoking-, and drinking-adjusted OR 1.514, 95% CI 1.005-2.282, p = 0.047) and the recessive model (age-, smoking-, and drinking-adjusted OR 1.601, 95% CI 1.078-2.379, p = 0.020). However, for females, ALDH2*2/*2 genotype was a protective factor for cerebral infarction in the co-dominant model (age-, smoking-, and drinking-adjusted OR 0.450 95% CI 0.215-0.941, p = 0.034) and the recessive model (age-, smoking-, and drinking-adjusted OR 0.440, 95% CI 0.214-0.903, p = 0.025). Further, logistic regression analysis revealed that age, smoking, hypertension, hyperlipidemia, and hypercholesterolemia were significant risks for the presence of cerebral infarction. In conclusion, these findings support an association of ALDH2 gene polymorphisms with ischemic stroke in a Chinese Hakka population. In particular, homozygote ALDH2*2/*2 may be a risk factor for cerebral infarction in males, but contribute to reduced risk for cerebral infarction in females.

[Effect of PR-957 on the formation of A1 reactive astrocytes].

OBJECTIVE: To study the effect of PR-957 on the formation of A1 reactive astrocytes. METHODS: The cerebral cortices of 1-day-old female rats were obtained and cultured for primary astrocytes. These cells were divided into 3 groups: control, lipopolysaccharide (LPS), and LPS+PR-957. The LPS group was treated with LPS (at a concentration of 5 µmol/L) for 48 hours; the LPS+PR-957 group was treated with PR-957 (at a final concentration of 200 nmol/L) for 1 hour and then LPS for 48 hours. Enzyme-linked immunosorbent assay was used to determine the expression of complement 3 (C3, a marker for A1 reactive astrocytes) and tumor necrosis factor alpha (TNF-α). Quantitative real-time PCR was used to determine the relative mRNA expression of glypican-6 (GPC6), SPARC-like 1 (SPARCL1), and lipocalin-2 (LCN2). All the above experiments were repeated three times independently. RESULTS: C3 expression was almost not observed in the control group, but was observed in both the LPS group and the LPS+PR-957 group, with significantly lower expression observed in the LPS+PR-957 group (P<0.05). The expression of TNF-α was consistent with that of C3. Compared with the control group, the LPS and the PS+PR-957 groups had significantly reduced mRNA expression levels of GPC6 and SPARCL1 but significantly increased mRNA expression level of LCN2 (P<0.001). Compared with the LPS group, the LPS+PR-957 group had significantly increased mRNA expression levels of GPC6 and SPARCL1 but significantly reduced mRNA expression level of LCN2 (P<0.001). CONCLUSIONS: LPS can induce the transformation from astrocytes to A1 reactive astrocytes, and PR-957 can inhibit the formation of LPS-induced A1 reactive astrocytes.

PPARγ Dysfunction in the Medial Prefrontal Cortex Mediates High-Fat Diet-Induced Depression.

Epidemiological studies suggest a bidirectional association between depression and obesity; however, the biological mechanisms that link the development of depression to a metabolic disorder remain unclear. Even though nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) agonists show anti-depressive effect, and high-fat diet-(HFD)-induced PPARγ dysfunction is involved in the pathogenesis of metabolic disorders, the neuronal PPARγ has never been studied in HFD-induced depression. Thus, we aimed to investigate the effect of neuronal PPARγ on depressive-like behaviors in HFD-induced obese mice.We fed male C57BL/6 J mice with HFD to generate obese mice and conducted a series of behavioral tests to assess the effects of HFD feeding on depression. We generated neuron-specific PPARγ knockout mice (NKO) to determine whether neuronal PPARγ deficiency was correlated with depressive-like behaviors. To further prove whether PPARγ in the medial prefrontal cortex (mPFC) neurons is involved in depressive-like behaviors, we applied AAV- CaMKIIα-Cre approach to specifically knockout PPARγ in the mPFC neurons of LoxP mice and used AAV-syn-PPARγ vectors to overexpress PPARγ in the mPFC neurons of NKO mice.We observed a low mPFC PPARγ level and an increase in depressive-like behaviors in the HFD-fed mice. Moreover, neuronal-specific PPARγ deficiency in mice induced depressive-like behaviors, which could be abolished by imipramine. Furthermore, overexpressing PPARγ in the mPFC reversed the depressive-like behaviors in HFD-fed mice as well as in neuronal-specific PPARγ knockout mice.These results implicate that dysregulation of neuronal PPARγ in the mPFC may contribute to an increased risk for depression in obese populations.

[Effects of human Livin gene down-regulation by RNA interference on xenograft of transplantation tumor induced by SPC-A1 in nude mice].

OBJECTIVE: To explore the in vivo inhibitory effect of Livin gene silencing by RNA interference on xenograft of lung adenocarcinoma SPC-A-1 cells in BALB/C nude mice. METHODS: Three different BALB/C nude mice models were established by subcutaneously inoculating differently treated SPC-A-1 cells into 3 nude mice groups: the blank control group was inoculated with blank SPC-A-1 cells, while the negative group was inoculated with cells transfected with lentivirus-delivered negative shRNA, the experimental group was inoculated with cells with lentivirus-delivered Livin shRNA. Then the growth of tumors was observed, and the volume and weight of the tumors were measured at different time points. The curve of tumor growth was then described, and the inhibition rate was calculated. Livin gene expression in the tumor tissues was determined by RT-PCR and Immunohistochemistry. Cell apoptosis of tumor tissues was detected by TUNEL. RESULTS: Slower tumor growth, smaller tumor volume and lighter tumor weight were observed in the experimental group as compared to the blank and negative groups (F = 70.509, P < 0.01; F = 12.821, P < 0.01). The inhibition rate of tumor volume was (59.5 ± 3.4)%, and the inhibition rate of tumor weight was (71.1 ± 5.6)%. Livinα mRNA and Livinß mRNA expressions in the experimental group were significantly lower than the 2 control groups [(37.2 ± 1.6)% versus (63.3 ± 3.8)%, (66.1 ± 2.6)%; (29.4 ± 1.1)% versus (53.2 ± 3.4)%, (52.3 ± 3.1)% (F(α) = 45.309, P < 0.01; F(ß) = 30.076, P < 0.01)]. Livin protein expression level was also significantly lower than the blank and the negative groups [(15.3 ± 2.8)% versus (51.3 ± 2.1)%, (52.5 ± 2.5)%, F = 78.92, P < 0.01]. The apoptosis rate in the experimental group was significantly higher than that in the 2 control groups [(35.4 ± 3.2)% versus (5.4 ± 1.3)%, (8.6 ± 1.5)%, F = 14.509, P < 0.01]. CONCLUSION: The lentivirus-delivered Livin shRNA was shown to inhibit the proliferation of transplantation tumor of lung carcinoma effectively, and Livin may be a target for gene therapy in lung cancer.

Livin abrogates apoptosis of SPC-A1 cell by regulating JNKI signaling pathway.

Livin, a novel member of inhibitors of apoptosis protein, is highly expressed in tumor tissues. It is a potential target in tumor therapy. Silencing its gene expression has been found to promote tumor cell apoptosis or increase tumor sensitivity to therapies. This paper studied the effect of livin anti-apoptotic activity and examined its molecular mechanisms. In the study, higher levels of cell apoptosis were measured by FACS in the experiment group with livin expression silenced than that in controls (P < 0.05). After livin gene expression was knocked down, cleaved caspase-3 protein was up-regulated but caspase-3 mRNA expression was almost the same, the phosphorylated JNK1 protein was down-regulated but JNK1 mRNA and total JNK1 protein expression was approximately the same too. The results suggest that livin may exert anti-apoptotic action on SPC-A1 by activating JNK1 signaling pathway and inhibiting caspase-3 activation.

Loss of RUNX3 expression correlates with differentiation, nodal metastasis, and poor prognosis of gastric cancer.

BACKGROUND: RUNX3 is a major growth regulator of gastric epithelial cells that is involved in gastric tumorigenesis in both humans and mice. In this study, we investigated the involvement of RUNX3 in tumor progression, and in the prognosis of human gastric cancer. METHODS: We analyzed the extent of RUNX3 protein expression by immunohistochemistry in 95 primary gastric adenocarcinomas, and correlated expression levels with clinicopathological parameters. We examined the effects of pFlag/RUNX3 on cell growth, apoptosis, and caspase-3 expression in AGS and SNU1 gastric cancer cell lines by colony-forming assay, terminal deoxynucleotidyl transferase (TdT)-mediate deoxyuridine triphosphatase (dUTP) nick-end labeling (TUNEL) assay, and Western blot analysis, respectively. The pFlag/RUNX3 effects on AGS invasion and migration potentials were also evaluated. RESULTS: RUNX3 expression was lost in 37 (39%) cases of gastric cancer. The expression of RUNX3 in diffuse- and mixed-type cancers was less frequent than expression in intestinal-type cancer (P < 0.001 and P = 0.001, respectively). In addition, the loss of RUNX3 expression was associated with lymph node metastasis (P = 0.02), and correlated with poor gastric cancer survival (P = 0.018). The growth of gastric cancer cells was suppressed after pFlag/RUNX3 transfection. The re-expression of RUNX3 resulted in the upregulation of caspase-3 and promoted apoptosis. Furthermore, Re-expression of RUNX3 induced significant inhibitions of AGS cell invasion and migration in vitro. CONCLUSIONS: This work shows that loss of RUNX3 expression is highly associated with lymph node metastasis and poor prognosis of gastric cancer. The re-expression of RUNX3 may induce apoptosis and inhibit the growth as well as invasion/migration of cancer cells. These results indicate that the targeting of the RUNX3 pathway could represent a potential modality for treating gastric cancer.

Peroxisome proliferator-activated receptor gamma-independent suppression of androgen receptor expression by troglitazone mechanism and pharmacologic exploitation.

Previously, we showed that the peroxisome proliferator-activated receptor gamma (PPARgamma) agonist troglitazone at high doses was able to suppress androgen receptor (AR) expression in LNCaP prostate cancer cells independently of PPARgamma. Pharmacologic exploitation of this finding led to STG28, a PPARgamma-inactive analogue of troglitazone with substantially higher potency in AR repression. Considering the pivotal role of AR in prostate tumorigenesis, this study investigates the mechanism by which troglitazone and derivatives suppress AR expression in LNCaP cells. Reverse transcription-PCR and reporter gene assays indicate that this drug-induced AR repression occurs at both mRNA and protein levels. Evidence suggests that troglitazone and derivatives mediate the transcriptional repression of AR by facilitating the ubiquitin-dependent proteasomal degradation of the transcriptional factor Sp1. These agents also cause the proteolysis of two proteins that regulate Sp1-mediated transcription (i.e., the TATA-binding protein-associated factor TAF(II)250 and cyclin D1). However, their involvement in the transcriptional repression of AR is refuted by the finding that small interfering RNA knockdown of these two regulatory proteins does not cause AR down-regulation. STG28 does not cause significant reduction in Sp1 or AR expression in normal prostate epithelial cells. This discriminatory effect underscores the differential susceptibility of malignant versus normal cells to the inhibitory effect of STG28 on cell viability. From a translational perspective, STG28 provides a proof of principle that potent AR-ablative agents could be developed through structural modifications of troglitazone. Moreover, as the control of Sp1 degradation remains unclear, STG28 represents a unique pharmacologic probe to investigate the ubiquitin-proteasome system that regulates Sp1 proteolysis.

Disulfide-cross-linked PEG-block-polypeptide nanoparticles with high drug loading content as glutathione-triggered anticancer drug nanocarriers.

The development of stimuli-responsive drug carrier systems enabling to deliver high doses of anti-cancer drugs to tumor tissues is still urgently needed. In this study, we report the preparation of reduction-responsive methoxypolyethylene glycol-block-(poly(l-lysine)-co-poly(l-tyrosine)) (mPEG-b-(PLL-co-PLY)) nanoparticles (NPs) exhibiting sizes smaller than 100 nm and high drug loading content (DLC) of doxorubicin (DOX) by selecting the Lys and Tyr residues as the polypeptide building blocks. The disulfide-cross-linked mPEG-b-(PLL-co-PLY) assemblies with sizes can be tuned by varying the polypeptide composition followed by subsequent disulfide-cross-linking. Cytotoxicity assays showed that the Dox-loaded NPs exhibited efficient cell internalization and proliferation inhibition toward cancer cells, whereas the copolymers exhibited low hemolysis to human red blood cells and excellent biocompatibility to both normal and cancer cells. The enhanced internalization and cytotoxicity of DOX-NPs can be possible due to their small size and their reduction-responsive property. Anticancer studies using C57BL/6 mice bearing LLC tumor model showed that the DOX-loaded NPs significantly suppressed tumor growth and prolonged the survival of tumor-bearing mice without obvious body weight loss and damage to major organs. This approach provides a platform for developing stimuli-responsive, polypeptide-based drug delivery systems with high DLC for cancer treatment.

[Diagnostic value of ischemia-modified albumin in patients with acute coronary syndrome].

OBJECTIVE: To investigate the diagnostic value of ischemia-modified albumin (IMA) for patients with acute coronary syndrome (ACS). METHODS: We detected the IMA levels by albumin cobalt-binding (ACB) test and observed its dynamic changes in 492 patients with ACS, 74 patients with high blood pressure, 78 patients with viral myocarditis (VMC), 395 patients with acute chest pain (133 patients with acute ACS and 262 follow-up patients due to chest pain), 68 patients underwent percutaneous coronary intervention (PCI) and 830 healthy controls. Cardiac troponin I (cTnI) levels were assayed and electrocardiogram (ECG) recorded in patients with ACS. RESULTS: The optimal diagnostic cutoff point for IMA in this study population was found to be 0.45 ABSU by ROC analysis. The IMA level (ABSU) in ACS group (0.55 +/- 0.11) was significantly higher than that in VMC group (0.38 +/- 0.11) and IMA levels in ACS and VMC groups were both higher than that in control and high blood pressure groups (0.34 +/- 0.08 and 0.35 +/- 0.08, all P < 0.05). IMA levels and the positive rates in patients with ACS were significantly higher (0.54 +/- 0.12 vs 0.44 +/- 0.12, 77.4% vs 39.3%, all P < 0.01) than those in chest pain follow-up group. In 133 patients with ACS, positive rate for IMA was significantly higher than that for cTnI within 1 h of admission (82.0% vs 40.6%, P < 0.01), and was similar at 6 - 24 h after admission (96.2% vs. 95.5%, P > 0.05). In 72 patients presenting to the emergency center within 3 h of acute chest pain and with negative cTnI, positive rate for IMA was 86.1% and for ECG 72.2%, the sensitivity for ACS diagnosis rised to 93.1% with both methods. The IMA leve was higher immediately after PCI than that before PCI (P < 0.05). IMA levels peaked 1d after hospitalization, then decreased gradually and returned to normal 14 days later. CONCLUSIONS: IMA was a useful biochemical marker for the early diagnosis of ACS.

[Increased expression of placenta growth factor in lung tissue of paraquat-induced rat pulmonary fibrosis model].

OBJECTIVE: To investigate the dynamic expression of placenta growth factor (PLGF) in the lungs with paraquat (PQ)-induced pulmonary fibrosis. METHODS: Forty-two adult healthy female Sprague-Dawley (SD) rats were randomly divided into two groups: the control group and the PQ group. Each group was divided into three subgroups, seven animals each. The rats in PQ group were treated intragastrically (ig) with PQ (40 mg/kg) and the rats in control group were treated with the same volume of saline at the beginning of the experiment. The animals of model and control group were sacrificed and lungs were harvested on the 7(th), 14(th) and 28th days respectively. A semiquantitative assay of histological examination and hydroxyproline in lung tissues were used to determine the severity of alveolitis and fibrosis. RT-PCR and immunohistochemistry were used to detect the mRNA and protein expression of PLGF. RESULTS: Hydroxyproline contents in lung tissue were significantly increased after PQ administration. Inflammatory cell infiltration and fibrotic scores were more prominent in the model group compared to the control group. Further study showed that PLGF mRNA on day 7, 14 and 28 (1.28 +/- 0.29, 0.80 +/- 0.07, 0.65 +/- 0.13) and positive index of protein expression (2.27 +/- 0.34, 1.78 +/- 0.41, 1.25 +/- 0.69) in the PQ group were all upregulated as compared with those of the control group. CONCLUSION: The PLGF expression in the lung tissue in rats with paraquat-induced pulmonary fibrosis is upregulated.

P-glycoprotein attenuates DNA repair activity in multidrug-resistant cells by acting through the Cbp-Csk-Src cascade.

Recent studies have demonstrated that P-glycoprotein (P-gp) expression impairs DNA interstrand cross-linking agent-induced DNA repair efficiency in multidrug-resistant (MDR) cells. To date, the detailed molecular mechanisms underlying how P-gp interferes with Src activation and subsequent DNA repair activity remain unclear. In this study, we determined that the C-terminal Src kinase-binding protein (Cbp) signaling pathway involved in the negative control of Src activation is enhanced in MDR cells. We also demonstrated that cells that ectopically express P-gp exhibit reduced activation of DNA damage response regulators, such as ATM, Chk2, Braca1 and Nbs1 and hence attenuated DNA double-strand break repair capacity and become more susceptible than vector control cells to DNA interstrand cross-linking (ICL) agents. Moreover, we demonstrated that P-gp can not only interact with Cbp and Src but also enhance the formation of inhibitory C-terminal Src kinase (Csk)-Cbp complexes that reduce phosphorylation of the Src activation residue Y416 and increase phosphorylation of the Src negative regulatory residue Y527. Notably, suppression of Cbp expression in MDR cells restores cisplatin-induced Src activation, improves DNA repair capacity, and increases resistance to ICL agents. Ectopic expression of Cbp attenuates cisplatin-induced Src activation and increases the susceptibility of cells to ICL agents. Together, the current results indicate that P-gp inhibits DNA repair activity by modulating Src activation via Cbp-Csk-Src cascade. These results suggest that DNA ICL agents are likely to have therapeutic potential against MDR cells with P-gp-overexpression.

Promoter hypermethylation of LGALS4 correlates with poor prognosis in patients with urothelial carcinoma.

Galectine-4 (gal-4), encoded by the LGALS4 gene, was recently shown to exhibit a tumor suppressive effect in colorectal carcinoma and pancreatic adenocarcinoma, although how the expression of this gene is regulated remains unknown. No reports describe the significance of gal-4 in the malignant potential of urothelial tumors. Thus, we analyzed LGALS4 methylation and gene expression and their clinical relevance and biological function in urothelial carcinoma (UC). LGALS4 methylation was initially identified as a progression biomarker for UC patients through genome-wide DNA methylation profiling of 16 tumor samples. Bisulfite sequencing PCR and immunohistochemistry were performed to validate the promoter methylation and expression of LGALS4. We used quantitative methylation-specific PCR to determine the methylation levels of LGALS4 normalized to ACTB in the tumor samples of 79 UC patients and compared the levels between patients with different clinicopathological characteristics. The association with survival probability was analyzed with the Kaplan-Meier method and Cox regression analysis. The ectopic expression of gal-4 in cancer cell lines was used to address its biological function in UC in vitro. The promoter hypermethylation of LGALS4 (>2.51, log10 scale) revealed a positive correlation with high levels of both histological grade and tumor T category and with lymph node metastasis (all P≤0.001). In addition, LGALS4 hypermethylation was an independent predictor of inferior survival in UC patients (P<0.05). The ectopic expression studies demonstrated that gal-4 suppressed urothelial cancer cell growth, migration, and invasion. Thus, LGALS4 may function as a tumor suppressor gene in UC progression. Our findings provide evidence that methylation-mediated LGALS4 gene repression may be involved in urothelial tumor progression.

[Changes in gelatinases expression and activity in human atria during atrial fibrillation].

OBJECTIVE: To determine whether expression and activity of atrial gelatinases are altered in patients with atrial fibrillation (AF). METHODS: The right atrial tissue samples were taken from 75 patients with rheumatic heart disease who underwent heart valve replacement surgery. 34 patients were in sinus rhythm, 11 patients had paroxysmal AF and 30 patients had persistent AF. The mRNA and protein level of MMP-2, MMP-9, TIMP-1, TIMP-2 were measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western-blotting analysis respectively. The activity of MMP-2 and MMP-9 was measured by zymographic analysis. RESULTS: (1) The mRNA level of MMP-2 increased significantly in the persistent AF group followed by the paroxysmal AF group compared with the sinus rhythm group (P < 0.01, respectively). MMP-9 mRNA expression remained compatible within groups (P > 0.05). MMP-2 and MMP-9 protein expression was prominent in the persistent AF group compared with the sinus rhythm and paroxysmal AF groups (P < 0.01), the significant difference was also observed between the paroxysmal AF and sinus groups (P < 0.05). (2) TIMP-1 and TIMP-2 expression at mRNA and protein level were all down-regulated in the persistent AF group compared with the sinus rhythm group (P < 0.05), however, the trends of reduction did not reach statistical significance in the paroxysmal AF group (P > 0.05) except that of the mRNA level of TIMP-2 (P < 0.05). (3) The activity of MMP-2 and MMP-9 significantly increased in both paroxysmal AF and persistent AF groups compared with the sinus rhythm group (P < 0.05). The significant difference in MMP-9 was also observed between the persistent AF and paroxysmal AF groups (P < 0.01). (4) MMP-2 and MMP-9 expression at mRNA and protein level were positively correlated with left atrial dimension and AF duration (P < 0.05) and were negatively correlated with the mRNA and protein level of TIMP-2 and TIMP-1 respectively (P < 0.01). CONCLUSIONS: The upregulation of MMP-2,9 gene expression and activity, along with the selective downregulation of TIMP-1,2 may have contributed to the atrial structural remodeling during AF through influencing collagen metabolism.

[Clinical on molecular basis of atrial fibrosis in patients with atrial fibrillation investigation].

OBJECTIVE: To determine the molecular mechanisms involved in atrial fibrosis which occurs in patients with atrial fibrillation (AF) and to investigate their effects on the initiation and maintenance of AF. METHODS: The right atrial tissue samples were taken from 73 patients with rheumatic heart disease who underwent heart valve replacement surgery. 34 patients had no history of AF (sinus rhythm group), 9 patients had paroxysmal AF and 30 patients had persistent AF. The mRNA content of collagen type I, collagen type III, MMP-2, TIMP-1, TIMP-2, TIMP-3 and TIMP-4 was measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and normalized to beta-actin or GAPDH. RESULTS: Compared to sinus rhythm group, the mRNA of collagen type I and MMP-2 increased significantly in the persistent AF group (all, P < 0.01), followed by the paroxysmal AF group (all, P < 0.05). The mRNA of collagen type III was slightly higher in both AF groups than in the sinus rhythm group, but the differences were not statistically significant (P > 0.05). The mRNA of TIMP-1, TIMP-2 and TIMP-3 was down-regulated in the persistent AF group (all, P < 0.01, respectively), however, the trends of reduction did not reach statistical significance in the paroxysmal AF group (P > 0.05). The mRNA of TIMP-4 remained compatible in each group. The mRNA of collagen type I was significantly correlated with left atrial dimension (r = 0.336, P = 0.004) and AF duration (r = 0.339, P = 0.003). The mRNA of MMP-2 was significantly correlated with the mRNA of TIMP-2 (r = -0.326, P = 0.006), the mRNA of collagen type I (r = 0.322, P = 0.006), left atrial dimension (r = 0.300, P = 0.011) and AF duration (r = 0.300, P = 0.010). CONCLUSION: The increased level of collagen type I associated with selective downregulation of TIMP-2 and upregulation of MMP-2 gene expression in atrium could be one of the molecular mechanisms of atrial fibrosis during atrial fibrillation, which correlates with the initiation and maintenance of AF.

Loss of ZBRK1 contributes to the increase of KAP1 and promotes KAP1-mediated metastasis and invasion in cervical cancer.

ZBRK1, a zinc finger protein that interacts with breast cancer 1 (BRCA1) and KRAB-ZFP-associated protein 1 (KAP1), has been suggested to serve as a tumor suppressor via repression of tumor metastasis/invasion. To date, the detailed molecular mechanisms for how BRCA1 and KAP1 participate in ZBRK1-mediated transcriptional repression, metastasis and invasion as well as the associated clinical relevance remain unclear. In this study, we demonstrated that both the N- and C-terminal domains of ZBRK1 are important for inhibiting cell proliferation and anchorage-independent growth in cervical cancer. Specifically, the N-terminal KRAB domain of ZBRK1 displayed a more crucial role in inhibiting metastasis and invasion through modulation of KAP1 function in a transcriptionally dependent manner. The loss of ZBRK1 results in an increase of KAP1 expression, which enhanced migration and invasion of cervical cancer cells both the in vitro and in vivo. Moreover, an inverse correlation of expression levels was observed between ZBRK1 and KAP1 following tumor progression from in situ carcinoma to invasive/metastatic cervical cancer specimens. Taken together, the current results indicate that a loss of ZBRK1 contributes to the increased expression of KAP1, potentiating its role to enhance metastasis and invasion.

Novel antitumor indolizino[6,7-b]indoles with multiple modes of action: DNA cross-linking and topoisomerase I and II inhibition.

A series of bis(hydroxymethyl)indolizino[6,7-b]indoles and their bis(alkylcarbamates) were synthesized for antitumor studies. These agents were designed as hybrid molecules of ß-carboline (topoisomerase inhibition moiety) and bis(hydroxymethyl)pyrrole (DNA cross-linking moiety). The preliminary antitumor studies indicated that these agents exhibited significant cytotoxicity against a variety of human tumor cells in vitro. Treatment of human breast carcinoma MX-1 xenograft-bearing nude mice with compounds 18b and 28c achieved more than 99% tumor remission. We also observed that 18a displayed potent therapeutic efficacy against human lung adenocarcinoma A549 and colon cancer HT-29 xenografts. These results revealed that compound 18a was more potent than irinotecan against HT-29 cells and was as potent as irinotecan against A549 cells in xenograft models. Furthermore, we demonstrated that these derivatives possess multiple modes of action, such as induction of DNA cross-linking, inhibition of topoisomerase I and II, and cell-cycle arrest at the S-phase.

ZBRK1 acts as a metastatic suppressor by directly regulating MMP9 in cervical cancer.

The BRCA1-interacted transcriptional repressor ZBRK1 has been associated with antiangiogenesis, but direct evidence of a tumor suppressor role has been lacking. In this study, we provide evidence of such a role in cervical carcinoma. ZBRK1 levels in cervical tumor cells were significantly lower than in normal cervical epithelial cells. In HeLa cervical cancer cells, enforced expression inhibited malignant growth, invasion, and metastasis in a variety of in vitro and in vivo assays. Expression of the metalloproteinase MMP9, which is known to be an important driver of invasion and metastasis, was found to be inversely correlated with ZBRK1 in tumor tissues and a target for repression in tumor cells. Our findings suggest that ZBRK1 acts to inhibit metastasis of cervical carcinoma, perhaps by modulating MMP9 expression.

Thiazolidinediones modulate the expression of beta-catenin and other cell-cycle regulatory proteins by targeting the F-box proteins of Skp1-Cul1-F-box protein E3 ubiquitin ligase independently of peroxisome proliferator-activated receptor gamma.

Considering the role of aberrant beta-catenin signaling in tumorigenesis, we investigated the mechanism by which the peroxisome proliferator-activated receptor gamma (PPARgamma) agonist troglitazone facilitated beta-catenin down-regulation. We demonstrate that troglitazone and its more potent PPARgamma-inactive analogs Delta2TG and STG28 mediated the proteasomal degradation of beta-catenin in prostate cancer cells by up-regulating the expression of beta-transducin repeat-containing protein (beta-TrCP), an F-box component of the Skp1-Cul1-F-box protein E3 ubiquitin ligase. Evidence indicates that although small interfering RNA-mediated beta-TrCP knockdown protected cells against STG28-facilitated beta-catenin ablation, ectopic beta-TrCP expression enhanced the degradation. The involvement of beta-TrCP in beta-catenin degradation was also corroborated by the pull-down analysis and the concurrent down-regulation of known beta-TrCP substrates examined, including Wee1, Ikappabetaalpha, cdc25A, and nuclear factor-kappaB/p105. Furthermore, glycogen synthase kinase-3beta represented a key regulator in the effect of these thiazolidinedione derivatives on beta-catenin proteolysis even though these agents increased its phosphorylation level. It is noteworthy that this drug-induced beta-TrCP up-regulation was accompanied by the concomitant down-regulation of Skp2 and Fbw7, thereby affecting many of the target proteins of these two F-box proteins (such as p27 and cyclin E). As a consequence, the ability of troglitazone to target these F-box proteins provides a molecular basis to account for its reported effect on modulating the expression of aforementioned cell-cycle regulatory proteins. Despite this complicated mode of pharmacological actions, normal prostate epithelial cells, relative to LNCaP cells, were less susceptible to the effects of STG28 on modulating the expression of beta-catenin and beta-TrCP, suggesting the translation potential of using STG28 as a scaffold to develop more potent chemopreventive agents.