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Lihong Yin

Publications and source records attributed to Lihong Yin.

13 recordsLinked to original sources
PubMed2006

Overexpression of PKCepsilon sensitizes LNCaP human prostate cancer cells to induction of apoptosis by bryostatin 1.

Phorbol 12-myristate 13-acetate (PMA)-induced apoptosis of androgen sensitive LNCaP human prostate cancer cells is a well known phenomenon that involves prolonged translocation of multiple protein kinase C (PKC) isozymes to nonnuclear membranes. We have shown recently that PMA-induced death of C4-2 cells, androgen hypersensitive derivatives of LNCaP cells, requires both PKCdelta and a redundant pathway that includes PKCs alpha and epsilon. In contrast, it has been reported that overexpression of murine PKCepsilon in LNCaP cells renders those cells resistant to PMA-induced death, as well as androgen insensitive. Here we report that inducible or constitutive overexpression of human PKCepsilon does not alter the sensitivity of LNCaP cells to either PMA or androgen, nor does it alter expression of caveolin-1 or phosphorylated Rb, reported effects of overexpression of murine PKCepsilon. Moreover, overexpression of very high amounts of PKCepsilon sensitized LNCaP cells to induction of apoptosis by bryostatin 1, a non tumor-promoting activator and down-regulator of PKC isozymes that blocks PMA-induced apoptosis of parental LNCaP cells, mimicked our previous results with overexpression of PKCalpha in LNCaP cells. Given reports that overexpression of PKCepsilon is frequent in human prostate tumors, our results may have important implications for a potential prostate cancer therapy.

Antineoplastic Agents↗
PubMed2006

Calcium instabilities in mammalian cardiomyocyte networks.

The degeneration of a regular heart rhythm into fibrillation (a chaotic or chaos-like sequence) can proceed via several classical routes described by nonlinear dynamics: period-doubling, quasiperiodicity, or intermittency. In this study, we experimentally examine one aspect of cardiac excitation dynamics, the long-term evolution of intracellular calcium signals in cultured cardiomyocyte networks subjected to increasingly faster pacing rates via field stimulation. In this spatially extended system, we observed alternans and higher-order periodicities, extra beats, and skipped beats or blocks. Calcium instabilities evolved nonmonotonically with the prevalence of phase-locking or Wenckebach rhythm, low-frequency magnitude modulations (signature of quasiperiodicity), and switches between patterns with occasional bursts (signature of intermittency), but period-doubling bifurcations were rare. Six ventricular-fibrillation-resembling episodes were pace-induced, for which significantly higher complexity was confirmed by approximate entropy calculations. The progressive destabilization of the heart rhythm by coexistent frequencies, seen in this study, can be related to theoretically predicted competition of control variables (voltage and calcium) at the single-cell level, or to competition of excitation and recovery at the cell network level. Optical maps of the response revealed multiple local spatiotemporal patterns, and the emergence of longer-period global rhythms as a result of wavebreak-induced reentries.

Action Potentials↗
PubMed2005

Rapid detection of single nucleotide polymorphisms related with lung cancer susceptibility of Chinese population.

Genetic variations have been thought to contribute to individual differences in lung cancer susceptibility. In our study, the possibility of an association of CYP1B1, GSTP1 and hOGG1 genetic polymorphisms with lung cancer was investigated in Chinese population of Nanjing, by a new single nucleotide polymorphism (SNP) typing approach of di-allele-specific-amplification with artificially modified primers (diASA-AMP) technique. A matched case-control study of 227 patients with lung cancer was conducted to detect CYP1B1 Leu432Val, GSTP1 Ile105Val and hOGG1 Ser326Cys polymorphisms. Genotypes were analyzed by diASA-AMP technique. Results did not show a significant difference in distributions of allele frequencies or genotypes of CYP1B1, GSTP1 and hOGG1 between two groups. However, stratifying on smoking status demonstrated that CYP1B1 432Val genotype had a slightly combined effect on lung cancer with smoker subjects (OR=2.78, 95%CI=1.46-5.29). The interaction between GSTP1 105Val mutation and smoking in the development of lung cancer were not detected, nor was hOGG1 326Cys mutation. Variant allele frequencies of CYP1B1, GSTP1 and hOGG1 in control group were similar to other reports of Chinese population. The sequencing results of CYP1B1, GSTP1 and hOGG1 matched the ones of diASA-AMP technique. CYP1B1 432Val polymorphism may modulate the individual susceptibility of lung cancer among smokers in Chinese population. GSTP1 Ile105Val and hOGG1 Ser326Cys polymorphisms were not found to be risk factors of lung cancer in this study. The method diASA-AMP is rapid, specific and cost-effective. It can be used for rapid detection of the genes related with tumor susceptibility of population.

Adult↗
PubMed2005

KiSS1 suppresses metastasis in human ovarian cancer via inhibition of protein kinase C alpha.

Metastasis is a vital target for cancer treatment, since the majority of cancer patients die from metastatic, rather than the primary disease. KiSS1 has been identified as a metastasis suppressor gene in melanoma and breast carcinomas. We show here that KiSS1 is also a metastasis suppressor in human ovarian cancer. Overexpression of KiSS1 in ovarian cancer cells inhibits cell migration induced by serum or lysophosphatidic acid (LPA), and colonization in soft agar, but not cell proliferation, representing the characteristics of a metastasis suppressor gene. Furthermore, using an experimental metastatic mouse model, we show that expression of KiSS1 in SKOV3 ovarian cancer cells suppresses >50% metastatic colonization in mice (P < 0.0001). We find that activating protein kinase C (PKC) reverses about 80% of the inhibited cell migration induced by KiSS1, while down-regulation of PKCalpha with shRNA restores KiSS1 effect, providing evidence that inhibiting PKCalpha may be an important mechanism of the effect of KiSS1. These results suggest that KiSS1 is a metastasis suppressor of ovarian cancer and may be a potential molecular target for the treatment.

Animals↗
PubMed2005

Electrospun fine-textured scaffolds for heart tissue constructs.

The structural and functional effects of fine-textured matrices with sub-micron features on the growth of cardiac myocytes were examined. Electrospinning was used to fabricate biodegradable non-woven poly(lactide)- and poly(glycolide)-based (PLGA) scaffolds for cardiac tissue engineering applications. Post-processing was applied to achieve macro-scale fiber orientation (anisotropy). In vitro studies confirmed a dose-response effect of the poly(glycolide) concentration on the degradation rate and the pH value changes. Different formulations were examined to assess scaffold effects on cell attachment, structure and function. Primary cardiomyocytes (CMs) were cultured on the electrospun scaffolds to form tissue-like constructs. Scanning electron microscopy (SEM) revealed that the fine fiber architecture of the non-woven matrix allowed the cardiomyocytes to make extensive use of provided external cues for isotropic or anisotropic growth, and to some extent to crawl inside and pull on fibers. Structural analysis by confocal microscopy indicated that cardiomyocytes had a preference for relatively hydrophobic surfaces. CMs on electrospun poly(L-lactide) (PLLA) scaffolds developed mature contractile machinery (sarcomeres). Functionality (excitability) of the engineered constructs was confirmed by optical imaging of electrical activity using voltage-sensitive dyes. We conclude that engineered cardiac tissue structure and function can be modulated by the chemistry and geometry of the provided nano- and micro-textured surfaces. Electrospinning is a versatile manufacturing technique for design of biomaterials with potentially reorganizable architecture for cell and tissue growth.

Absorbable Implants↗
PubMed2004

Phorbol ester-induced apoptosis of C4-2 cells requires both a unique and a redundant protein kinase C signaling pathway.

Phorbol 12-myristate 13-acetate (PMA) potently induces apoptosis of LNCaP human prostate cancer cells. Here, we show that C4-2 cells, androgen-hypersensitive derivatives of LNCaP cells, also are sensitive to PMA-induced apoptosis. Previous reports have implicated activation of protein kinase C (PKC) isozymes alpha and delta in PMA-induced LNCaP apoptosis using overexpression, pharmacological inhibitors, and dominant-negative constructs, but have left unresolved if other isozymes are involved, if there are separate requirements for individual PKC isozymes, or if there is redundancy. We have resolved these questions in C4-2 cells using stable expression of short hairpin RNAs to knock down expression of specific PKC isozymes individually and in pairs. Partial knockdown of PKCdelta inhibited PMA-induced C4-2 cell death almost completely, whereas near-complete knockdown of PKCalpha had no effect. Knockdown of PKCepsilon alone had no effect, but simultaneous knockdown of both PKCalpha and PKCepsilon in C4-2 cells that continued to express normal levels of PKCdelta inhibited PMA-induced apoptosis. Thus, our data indicate that there is an absolute requirement for PKCdelta in PMA-induced C4-2 apoptosis but that the functions of PKCalpha and PKCepsilon in apoptosis induction are redundant, such that either one (but not both) is required. Investigation of PMA-induced events required for LNCaP and C4-2 apoptosis revealed that p38 activation is dependent on PKCdelta, whereas induction of retinoblastoma protein hypophosphorylation requires both PKC signaling pathways and is downstream of p38 activation in the PKCdelta pathway.

Apoptosis↗
PubMed2004

Scaffold topography alters intracellular calcium dynamics in cultured cardiomyocyte networks.

Structural and functional changes ensue in cardiac cell networks when cells are guided by three-dimensional scaffold topography. We report enhanced synchronous pacemaking activity in association with slow diastolic rise in intracellular Ca2+ concentration ([Ca2+]i) in cell networks grown on microgrooved scaffolds. Topography-driven changes in cardiac electromechanics were characterized by the frequency dependence of [Ca2+]i in syncytial structures formed of ventricular myocytes cultured on microgrooved elastic scaffolds (G). Cells were electrically paced at 0.5-5 Hz, and [Ca2+]i was determined using microscale ratiometric (fura 2) fluorescence. Compared with flat (F) controls, the G networks exhibited elevated diastolic [Ca2+]i at higher frequencies, increased systolic [Ca2+]i across the entire frequency range, and steeper restitution of Ca2+ transient half-width (n = 15 and 7 for G and F, respectively, P < 0.02). Significant differences in the frequency response of force-related parameters were also found, e.g., overall larger total area under the Ca2+ transients and faster adaptation of relaxation time to pacing rate (P < 0.02). Altered [Ca2+]i dynamics were paralleled by higher occurrence of spontaneous Ca2+ release and increased sarcoplasmic reticulum load (P < 0.02), indirectly assessed by caffeine-triggered release. Electromechanical instabilities, i.e., Ca2+ and voltage alternans, were more often observed in G samples. Taken together, these findings 1) represent some of the first functional electromechanical data for this in vitro system and 2) demonstrate direct influence of the microstructure on cardiac function and susceptibility to arrhythmias via Ca(2+)-dependent mechanisms. Overall, our results substantiate the idea of guiding cellular phenotype by cellular microenvironment, e.g., scaffold design in the context of tissue engineering.

Animals↗
PubMed2004

Functional cardiac cell constructs on cellulose-based scaffolding.

Cellulose and its derivatives have been successfully employed as biomaterials in various applications, including dialysis membranes, diffusion-limiting membranes in biosensors, in vitro hollow fibers perfusion systems, surfaces for cell expansion, etc. In this study, we tested the potential of cellulose acetate (CA) and regenerated cellulose (RC) scaffolds for growing functional cardiac cell constructs in culture. Specifically, we demonstrate that CA and RC surfaces are promoting cardiac cell growth, enhancing cell connectivity (gap junctions) and electrical functionality. Being optically clear and essentially non-autofluorescent, CA scaffolds did not interfere with functional optical measurements in the cell constructs. Molding to follow fine details or complex three-dimensional shapes are additional important characteristics for scaffold design in tissue engineering. Biodegradability can be controlled by hydrolysis, de-acetylization of CA and cytocompatible enzyme (cellulase) action, with glucose as a final product. Culturing of cardiac cells and growth of tissue-like cardiac constructs in vitro could benefit from the versatility and accessibility of cellulose scaffolds, combining good adhesion (comparable to the standard tissue-culture treated polystyrene), molding capabilities down to the nanoscale (comparable to the current favorite in soft lithography-polydimethylsiloxane) with controlled biodegradability.

Action Potentials↗
PubMed2004

Fusobacterium nucleatum induces premature and term stillbirths in pregnant mice: implication of oral bacteria in preterm birth.

Fusobacterium nucleatum is a gram-negative anaerobe ubiquitous to the oral cavity. It is associated with periodontal disease. It is also associated with preterm birth and has been isolated from the amniotic fluid, placenta, and chorioamnionic membranes of women delivering prematurely. Periodontal disease is a newly recognized risk factor for preterm birth. This study examined the possible mechanism underlying the link between these two diseases. F. nucleatum strains isolated from amniotic fluids and placentas along with those isolated from orally related sources invaded both epithelial and endothelial cells. The invasive ability may enable F. nucleatum to colonize and infect the pregnant uterus. Transient bacteremia caused by periodontal infection may facilitate bacterial transmission from the oral cavity to the uterus. To test this hypothesis, we intravenously injected F. nucleatum into pregnant CF-1 mice. The injection resulted in premature delivery, stillbirths, and nonsustained live births. The bacterial infection was restricted inside the uterus, without spreading systemically. F. nucleatum was first detected in the blood vessels in murine placentas. Invasion of the endothelial cells lining the blood vessels was observed. The bacteria then crossed the endothelium, proliferated in surrounding tissues, and finally spread to the amniotic fluid. The pattern of infection paralleled that in humans. This study represents the first evidence that F. nucleatum may be transmitted hematogenously to the placenta and cause adverse pregnancy outcomes. The results strengthen the link between periodontal disease and preterm birth. Our study also indicates that invasion may be an important virulence mechanism for F. nucleatum to infect the placenta.

Amniotic Fluid↗
PubMed2004

[Interaction of beta-carotene on lipid peroxidation induced by cigarette smoke].

OBJECTIVE: To study the interaction of beta-carotene on lipid peroxidation induced by the smoke of cigarette. METHODS: Rat type II pneumocytes were isolated, cultured and then exposed to particles extracted from cigarette smoke and/or beta-carotene for 24 h. Malondialdehyde (MDA) in the cells was measured by TBA method. On the other hand, serum MDA of mice given beta-carotene supplements and/or exposed to cigarette smoke for 10 days was measured. RESULTS: The particles extracted from cigarette smoke increased the content of MDA in the rate type II pneumocytes, and the lipid peroxidation was antagonized by adding 0.5 microgram/ml of beta-carotene to the cells simultaneously. The results from the in vivo study showed that serum MDA levels were increased in the cigarette smoke-treated groups, and the lipid peroxidation was reduced by treating mice with 2.5 mg per kg body weight of beta-carotene. CONCLUSION: beta-carotene had an antagonistic effect on lipid peroxidation induced by cigarette smoke. The effective dosage of beta-carotene was 0.5 microgram/ml for rat pneumocytes and 2.5 mg/kg BW weight for mice.

Animals↗
PubMed2003

Polydnavirus of Campoletis chlorideae: characterization and temporal effect on host Helicoverpa armigera cellular immune response.

Polydnavirus was isolated from oviduct calyx in the parasitoid wasp Campoletis chlorideae (Hymenoptera: Ichneumonidae), and termed CcIV. The virus particles consist of fusiform nucleocapsids surrounded by two unit membrane envelopes. The DNAs purified from these viruses were found diversified in molecular weight and existed in nonequimolar concentrations. At least 20 different-sized bands were present after electrophoresis, and they ranged from approximately 3 to 26 kb. Persistence and gene expression of CcIV were examined in parasitized and virus-injected Helicoverpa armigera larvae. Viral DNA could be detected in the hemocyte of H. armigera at 30 min post-parasitization (p.p.), and persisted for 6 days. While no viral DNA increase was found, CcIV transcripts were first detected in host hemocytes at day 1 p.p. and continued for 5 days. Similar transcripts were observed in hemocytes from larvae that had been injected with calyx fluid or CcIV 24 h earlier. CcIV viral DNAs hybridized only with certain first-strand cDNAs from hemocytes, suggesting that only part of the CcIV genome was expressed in H. armigera. The pattern of CcIV gene expression was consistent with that of the inhibition of encapsulation for Sephadex G-10 and parasitoid eggs by host larvae. The recovery of host immune response at day 4 p.p. indicated that CcIV exhibited a partial and temporal effect on the host immune system and the developing parasitoid appeared to avoid encapsulation via different mechanisms.

Animals↗
PubMed2002

[Oxidative stress of cooking oil fume on rat type II lung cells].

The relationship between the oxidative stress and damages in rat type II lung cells exposed to cooking oil fume (COF) was studied. The cytotoxicity, DNA cross-links and DNA single strand breaks could be observed in the cells exposed to COF. The contents of MDA were increased and GSH were decreased significantly with exposure doses of COF and with time dependence. Pretreatment with antioxidant N-acetylcysteine (NAC) could reduce the toxicity of COF to the cells. The results suggested that cytotoxicity and DNA damages of rat type II lung cells induced by cooking oil fume might be related to the oxidative stress and the possible pathways might be the formation of lipid peroxides and interfering the GSH anti-oxidative systems of the cells.

Animals↗