In vivo and in vitro anti-inflammatory effects of Zao-Jiao-Ci (the spine of Gleditsia sinensis Lam.) aqueous extract and its mechanisms of action.

ETHNOPHARMACOLOGICAL RELEVANCE: Zao-Jiao-Ci (ZJC), as the spine of Chinese Honey locust (Gleditsia sinensis Lam.), is traditionally used as Chinese medicine to reduce inflammation. AIM OF THE STUDY: The present study aimed to investigate an anti-inflammatory effect of ZJC aqueous extract both in vitro and in vivo, as well as its underlying mechanisms. MATERIALS AND METHODS: Anti-inflammatory effect of ZJC aqueous extract was evaluated by using carrageenan-induced paw edema in rats. In addition, the inhibitory effects of ZJC on nitric oxide production, intracellular reactive oxygen species production, pro-inflammatory mediator expression and prostaglandin E2 (PGE2) production were determined by using LPS-activated RAW 264.7 cells. The anti-oxidant activity of ZJC was assessed using 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid assay. RESULTS: ZJC aqueous extract showed significant suppressive effect on paw edema in rats at 100mg/kg. Moreover, ZJC aqueous extract decreased the expression of cyclooxygenase (COX)-2 and significantly decreased the PGE2, tumor necrosis factor-α, interleukin (IL)-1ß and IL-6 production in LPS-activated macrophages in dose-dependent manners. ZJC aqueous extract inhibited the mRNA expression of these inflammatory cytokines as well. Furthermore, ZJC aqueous extract was found as an anti-oxidant and could inhibit ROS production in the LPS-induced cells. CONCLUSIONS: These findings show the potential of ZJC aqueous extract as a naturally occurring COX-2 inhibitor to reduce inflammation.

Combined therapy using bevacizumab and turmeric ethanolic extract (with absorbable curcumin) exhibited beneficial efficacy in colon cancer mice.

Turmeric is commonly used as a medicinal herb and dietary supplement. Its active ingredient, curcumin, has been shown to possess antitumor effects in colorectal cancer patients. However, poor absorption of curcumin in intestine impedes its wide clinical application. Our previous findings showed that the presence of turmerones increased the accumulation of curcumin inside colonic cells. Hence, we hypothesized that curcumin with turmerones or present in turmeric ethanolic extract would augment its anti-tumor activities in tumor-bearing mice. The pharmacokinetics of curcumin in different preparations (containing same amount of curcumin) were studied in mice. The anti-tumor efficacies of curcumin or turmeric extract (with absorbable curcumin) in combination with bevacizumab were further investigated in HT29 colon tumor-bearing mice. Pharmacokinetic results showed that the plasma curcumin level of turmeric extract-fed mice was the highest, suggesting turmeric extract had the best bioavailability of curcumin. Besides, combined turmeric extract plus bevacizumab treatment significantly inhibited the tumor growth. Such inhibitory effects were stronger than those of curcumin plus bevacizumab or bevacizumab alone and were comparable with those of 5-fluorouracil+leucovorin+oxaliplatin (FOLFOX) plus bevacizumab. Notably, there was no observable side effect induced by turmeric extract treatment while significant side effects were found in FOLFOX-treated mice. In conclusion, combination of turmeric extract with bevacizumab possessed potent anti-tumor effects without observable side effects, strongly suggesting the adjuvant use of turmeric extract in colorectal cancer therapy. Our current findings warrant the confirmation regarding the benefits arising from the combined use of bevacizumab and turmeric in colorectal cancer patients in the near future.

Multitargeted combination effects of a triherbal formulation containing ELP against osteoporosis: in vitro evidence.

OBJECTIVES: An anti-osteoporotic herbal formula ELP containing Epimedii Herba (E), Ligustri Lucidi Fructus (L) and Psoraleae Fructus (P) was studied to investigate the herb-herb interaction (or the possible synergistic effect) among each component and to identify the principal herbs in different modes of action. METHODS: Rat osteoblast-like UMR-106 cells proliferation, rat MSCs-derived osteoblastogenesis and RANKL-induced RAW 264.7 osteoclastogenesis were adopted to investigate the bone-forming activity and bone-degrading activity of the herbal extracts. In the statistical aspect, a modified Tallarida's approach was employed to assess the synergistic effects in herbal combinations. KEY FINDINGS: Psoraleae Fructus is the active herb for stimulating osteoblast proliferation, and mild synergy was detected in the pairwise combinations EL, LP and formula ELP. In osteoblastogenesis assay, E and L are the principal herbs for promoting osteoblast differentiation and significant synergy was detected in the pairwise combination EL. For inhibiting osteoclast formation, L is the active herb and significant synergy was detected in the 3-way combination ELP. CONCLUSIONS: The presence of E, L and P is essential for ELP formula as a whole to act against osteoporosis via enhancing bone formation and reducing bone reabsorption. An optimal dosage at 150 µg/ml was proposed for ELP based on our findings.

The aqueous extract of rhizome of Gastrodia elata Blume attenuates locomotor defect and inflammation after traumatic brain injury in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Traumatic brain injury (TBI) has an incident rate of 200-300 people per 100,000 annually in the developed countries. TBI has relatively high incidence at an early age and may cause long-term physical disability. Patients suffered from severe TBI would have motor and neuropsychological malfunctions, affecting their daily activities. Traditionally, Gastrodia elata Blume is a Chinese Medicines which was used for the head diseases, while their efficiency on reducing brain damage was still largely unknown. In the present study, we aimed to examine the effect of water extract of G. elata Blume (GE) against TBI and elucidate its underlying mechanism. MATERIALS AND METHODS: Sprague-Dawley rats were treated with GE for 7 days, immediately after controlled cortical impact-induced TBI. Impaired neurobehavioral functioning was measured on day 3 and 6 after TBI. Histology of TBI was examined to assess the extent of inflammation, and the expressions of pro-inflammatory cytokines were examined by immunofluorescence study on day 7. RESULTS: GE treatment significantly improved the impaired locomotor functions induced by TBI. GE treatment reduced inflammation and gliosis in the penumbral area. The increase in brain levels of pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-alpha observed in non-GE treated TBI rats were also reversed. CONCLUSIONS: GE treatment attenuated the locomotor deficit caused by TBI. The anti-inflammatory activity might be mediated by inhibition of pro-inflammatory cytokines responses in the TBI-brain.

Characteristics of stem cells derived from rat fascia: in vitro proliferative and multilineage potential assessment.

Fascia­derived stem cells (FDSCs) were previously isolated from the fascia of the gluteus maximus of the rat. However, the use of FDSCs as a cell source for musculoskeletal tissue engineering has not been compared with that of adipose­derived stem cells (ADSCs) and bone marrow­derived mesenchymal stem cells (BMSCs). Therefore, the present study aimed to compare the mesenchymal stem cell (MSC) and self­renewal stem cell markers, proliferative capacity and multilineage differentiation potential of these stem cells in vitro. The MSC and embryonic stem cell (ESC) marker profiles were compared using flow cytometry and quantitative polymerase chain reaction (qPCR). Their proliferative capacities were compared using 5­bromo­2'­deoxyuridine and MTT assays. Their osteogenic, adipogenic and chondrogenic differentiation potentials were compared using standard staining assays and qPCR. The FDSCs possessed similar cell morphology and immunophenotypic profiles with BMSCs and ADSCs. FDSCs demonstrated a similar expression pattern of ESC markers with ADSCs, which has higher expression of sex determining region Y­box (Sox)2 and octamer­binding transcription factor 4, and lower expression of Krüppel­like factor 4, when compared with BMSCs. FDSCs exhibited higher proliferation under serum­deprived conditions (0.5% FBS growth medium), and attained higher expression levels of collagen type I, α 2 and type II, α 1 as well as Sox9 mRNA than ADSCs and BMSCs upon chondrogenic induction. An increased amount of proteoglycan deposition was also observed in the FDSC group. However, lower levels of adipogenic and osteogenic marker expression in FDSCs were detected compared with ADSCs and BMSCs upon adipogenic and osteogenic induction, respectively. FDSCs possessed high chondrogenic potential, low osteogenic and adipogenic differentiation potential and were responsive to the induction signals for collagen­rich fascial structure regeneration. Therefore, FDSCs may represent an improved alternative cell source to conventional ADSCs and BMSCs for musculoskeletal tissue repair and tissue engineering, particularly for collagen­rich structures with poor vasculature.

Er-Miao-San, a traditional herbal formula containing Rhizoma Atractylodis and Cortex Phellodendri inhibits inflammatory mediators in LPS-stimulated RAW264.7 macrophages through inhibition of NF-κB pathway and MAPKs activation.

ETHNOPHARMACOLOGICAL RELEVANCE: Er-Miao-San (EMS) is a traditional Chinese herbal formulation that contains combinations of Rhizoma Atractylodis (RA) and Cortex Phellodendri (CP). It exhibits analgesic and anti-inflammatory activities and have been used for the treatment of various "Bi Zheng" for thousand years in China. The aims of the present study were to investigate the anti-inflammatory activities of EMS and elucidate the underlying mechanisms with regard to its molecular basis of action for the best combination. MATERIALS AND METHODS: The anti-inflammatory effects of EMS were studied by using lipopolysaccharide (LPS)-stimulated activation of nitric oxide (NO) and pro-inflammatory cytokine production in mouse RAW264.7 macrophages. Expression of inducible NO synthase (iNOS), mitogen-activated protein kinases (MAPKs) phosphorylation, p65 phosphorylation, inhibitor-κBα (IκBα) degradation, and NF-κB DNA-binding activity were further investigated. RESULTS: The present study demonstrated that EMS could suppress the production of NO in LPS-stimulated RAW264.7 macrophages. However, CP and RA did not have significant inhibitory effect on them. EMS also inhibited the production of tumor necrosis factor-alpha, interleukin-1 beta and macrophage chemotactic protein-1. Further investigations showed EMS could suppress iNOs expression and p38 phosphorylation. EMS significantly decreased the content of IκBα, reduced the level of phosphorylated p65 and suppressed the NF-κB DNA-binding activity. All these results suggested the inhibitory effects of EMS on the production of inflammatory mediators through the inhibition of the NF-κB pathway. CONCLUSIONS: Our results indicated that EMS inhibited inflammatory events and iNOS expression in LPS-stimulated RAW264.7 cells through the inactivation of the MAPK and NF-κB pathway. This study gives scientific evidence validating the use of EMS in treatment of patients with "Bi Zheng" in clinical practice in traditional Chinese medicine.

The effects of an antiosteoporosis herbal formula containing epimedii herba, ligustri lucidi fructus and psoraleae fructus on density and structure of rat long bones under tail-suspension, and its mechanisms of action.

An innovative anti-osteoporosis herbal formula containing epimedii herba, ligustri lucidi fructus and psoraleae fructus (ELP) has been previously shown its bone protecting effects in ovariectomized osteoporotic rats and also in post-menopausal osteopenic women. This study aimed to investigate the efficacy of ELP against bone loss during physical inactivity or weightlessness. A hindlimb unloading tail-suspended rat model was used for studying the effects of ELP on bone mineral density (BMD) and bone micro-architecture. For in vitro mechanistic studies, rat mesenchymal stem cells (MSCs) and mouse macrophage cells (RAW264.7) were used for studying the effects of ELP on osteogenic/adipogenic differentiations and osteoclastogenesis, respectively. Our data illustrated that ELP had a significant preventive effect against bone loss induced by tail-suspension (TS) at day 28 (p < 0.01) as indicated in the reduction in BMD loss and the preservation of bone micro-architecture. ELP could significantly promote the osteogenesis and suppress the adipogenesis (p < 0.05) in MSCs. Besides, significant inhibition of osteoclast formation (p < 0.01) was found in ELP-treated RAW264.7 cells upon receptor activator of nuclear factor kappa-B ligand induction. Our study presents the first scientific evidence that ELP had a significant preventive effect against bone loss induced by TS through the actions of enhancing osteogenesis, suppressing adipogenesis and osteoclastogenesis.

Application of Chinese herbal medicines to revitalize adult stem cells for tissue regeneration.

It has been established in the recent several decades that adult stem cells play a crucial role in tissue renewal and regeneration. Adult stem cells locate in certain organs can differentiate into functional entities such as macrophages and bone cells. Hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) are two of the most important populations of adult stem cells. The application of these stem cells offers a new insight in treating various pathological conditions, through replenishing cells of specific functions by turning on or off the differentiating program within quiescent stem cell niches. Apart from that, they are also capable to travel through the circulation, migrate to injury sites and differentiate to enhance regeneration process. Recently, Chinese medicine (CM) has shown to be potential candidates to activate adult stem cells for tissue regeneration. This review summarizes our own, as well as others' findings concerning the use of Chinese herbal medicine in the regulation processes of adult stem cells differentiation and their movement in tissue repair and rejuvenation. A number of Chinese herbs are used as therapeutic agents and presumably preventive agents on metabolic disorders. In our opinion, the activation of adult stem cells self-regeneration not only provides a novel way to repair tissue damage, but also reduces the use of targeted drug that adversely altering the normal metabolism of human subjects.

Computerized quantification of bone tissue and marrow in stained microscopic images.

Stained histological images assist physicians to identify different types of tissues or cells and their architectures. They can be applied on the diagnosis of various diseases and the assessment of treatment effects. Osteoporosis is an aging disease that reduces the density of bones and increases the risk of bone fracture. Literatures indicate that osteoporosis is associated with the ratio of trabecular bone tissues and bone marrow cells, and bones in osteoporosis patients consist of a significantly higher marrow fat content. Interactive segmentation of bone tissue and different types of bone marrow cells in high-resolution histological images, however, is a very tedious and labor-intensive process. The aim of this study is to develop an automatic algorithm to quantify the areas of different tissues such as the trabecular bones and yellow and red marrow cells. This image segmentation method consists of a series of mathematical morphological operation steps based on both the color and morphology features of tissues and was implemented in Matlab. The results obtained from the proposed method have been verified by comparing with those obtained interactively from an experienced histotechnician (Pearson correlation coefficient > 0.94, P < 0.001). The result suggests that the proposed algorithm can effectively assist physicians to quantify stained bone histological images.

Pro-bone and antifat effects of green tea and its polyphenol, epigallocatechin, in rat mesenchymal stem cells in vitro.

Green tea has been demonstrated recently as a potent bone supportive agent. Our previous studies showed that green tea and its polyphenolic constituents can promote bone-forming osteoblast activities and inhibit the bone-resorpting osteoclast formation. The objective of the present study was to investigate whether green tea and its components can regulate the osteogenic and adipogenic differentiation in pluripotent rat mesenchymal stem cells (MSCs). The rat MSCs were isolated from the bone marrow of tibiae and femora. The cells were treated with decaffeinated green tea extract (GTE) and six tea polyphenols under osteogenic induction. The alkaline phosphatase (ALP) activities and matrix calcium (Ca) deposition were assessed after 7 and 14 days of treatment. Our results demonstrated that GTE could significantly increase ALP dose dependently in the concentrations without cytotoxicity (0-100 µg/mL). Among six tested tea polyphenols, epigallocatechin (EGC) was shown to be the most effective in promoting osteogenic differentiation. At 20 µM, EGC increased ALP levels and Ca deposition significantly by 2.3- and 1.7-fold, respectively, when compared with the control group. EGC also increased the mRNA expression of bone formation markers runt-related transcription factor 2, ALP, osteonectin, and osteopontin. Furthermore, EGC demonstrated its antiadipogenicity by decreasing the adipocyte formation and inhibiting the mRNA expression levels of the adipogenic markers peroxisome proliferator-activated receptor γ, ccaat/enhancer-binding protein ß, and fatty acid binding protein 4. In conclusion, this is the first report of the dual action of green tea polyphenol EGC in promoting osteogenesis and inhibiting adipocyte formation in MSCs. Our results provide scientific evidence to support the potential use of green tea in supporting the bone against degenerative diseases such as osteoporosis.

Inflammatory tumour microenvironment is associated with superior survival in hepatocellular carcinoma patients.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) is an aggressive malignancy with few treatment options. As the status of the tumour immune microenvironment can affect progression of established tumours, we evaluated potential immune mechanisms associated with survival in HCC. METHODS: Immune gene expression profiles were analyzed in tumour and non-tumour liver tissues from resected HCC patients using quantitative PCR and immunohistochemistry. Tumour-infiltrating leukocytes (TILs) were isolated to verify the expression of immune genes and to identify proliferating TILs. These parameters were analyzed statistically in relation with patient survival and tumour phenotype (apoptosis and proliferation). RESULTS: The immune microenvironment within tumours was found to be heterogeneous, although globally more inert compared to the adjacent non-tumour liver tissue. Univariate analysis in 61 patients identified a group of innate immune genes whose expression within tumours is positively associated with patient survival. TNF, IL6 and CCL2 are the most significant genes, with TNF being an independent predictor of survival in multivariate analysis. The gene set includes macrophage and NK-associated molecules such as TLR4, TLR3, CCR2, NCR3. Most of these molecules are expressed by TILs. Importantly, proliferating immune cells, predominantly NK and T cells, are present in tumours of patients with longer survival, and exclusively in areas devoid of proliferating tumour cells. NK and CD8(+) T cell densities are correlated positively with tumour apoptosis, and negatively with tumour proliferation. CONCLUSIONS: Hence, an inflammatory immune microenvironment within HCC tumours could be an important means to control tumour progression via TIL activation and proliferation.

MAD2 expression and its significance in mitotic checkpoint control in testicular germ cell tumour.

Chromosomal instability (CIN) is a common characteristic in testicular germ cell tumour (TGCT). A functional mitotic checkpoint control is important for accurate chromosome segregation during mitosis. Mitotic arrest deficient 2 (MAD2) is a key component of this checkpoint and inactivation of MAD2 is correlated with checkpoint impairment. The aim of this study was to investigate the function of mitotic checkpoint control in TGCT cells and to study its association with MAD2 expression using 8 TGCT cell lines as well as 23 TGCT tissue samples. We found that in response to microtubule disruption, 6 of 8 TGCT cell lines (75%) failed to arrest in mitosis demonstrated by the decreased mitotic index and aberrant expression of mitosis regulators, indicating that mitotic checkpoint defect is a common event in TGCT cells. This loss of mitotic checkpoint control was correlated with reduced MAD2 protein expression in TGCT cell lines implicating that downregulation of MAD2 may play a critical role in an impaired mitotic checkpoint control in these cells. In addition, immunohistochemistry studies on 23 seminomas and 12 normal testis tissues demonstrated that nuclear expression of MAD2 was much lower in seminomas (p<0.0001) but cytoplasmic MAD2 expression was higher in seminomas (p=0.06) than normal samples. Our results suggest that aberrant MAD2 expression may play an essential role in a defective mitotic checkpoint in TGCT cells, which may contribute to CIN commonly observed in TGCT tumours.

Epstein-Barr virus infection alters cellular signal cascades in human nasopharyngeal epithelial cells.

Epstein-Barr virus (EBV) latent infection is a critical event in nasopharyngeal carcinoma (NPC) tumorigenesis. EBV-encoded genes have been shown to be involved in immune evasion and in the regulation of various cellular signaling cascades. To elucidate the roles of EBV in NPC development, stable infection of EBV in nasopharyngeal epithelial cell lines was established. Similar to primary tumors of NPC, these infected cells exhibited a type II EBV latency expression pattern. In this study, multiple cellular signaling pathways in EBV-infected cells were investigated. We first demonstrated that in vitro EBV infection resulted in the activation of STAT3 and NFkappaB signal cascades in nasopharyngeal epithelial cells. Increased expression of their downstream targets (c-Myc, Bcl-xL, IL-6, LIF, SOCS-1, SOCS-3, VEGF, and COX-2) was also observed. Moreover, EBV latent infection induced the suppression of p38-MAPK activities, but did not activate PKR cascade. Our findings suggest that EBV latent infection is able to manipulate multiple cellular signal cascades to protect infected cells from immunologic attack and to facilitate cancer development.

Stable expression of EBERs in immortalized nasopharyngeal epithelial cells confers resistance to apoptotic stress.

Epstein-Barr virus (EBV) infection is closely associated with the development of nasopharyngeal carcinoma (NPC). The EBV-encoded RNAs (EBERs) are the most abundant EBV transcripts (about 10(7) copies per cell) in EBV infected cells. However, the cellular function of EBER expression, particularly in nasopharyngeal epithelial cells, remains poorly understood. EBERs acquire secondary structures analogous to double-stranded RNA (dsRNA) and may bind to the double-stranded RNA-dependent protein kinase (PKR) and interfere with its function. Activation of PKR involves autophosphorylation resulting in protein synthesis inhibition and cellular apoptosis. Induction of cellular apoptosis by activation of PKR may be an antiviral response adopted by virally infected cells. We have examined the functional properties of EBER expression in an immortalized nasopharyngeal epithelial cell line (NP69). Expression of EBERs was achieved by transfecting the NP69 cells with an EBER-expressing plasmid, pESK10. The EBER-expressing NP69 cells attained a higher growth rate compared to cells transfected with control plasmid (pcDNA3). However, the EBER-expressing NP69 cells did not form colonies in soft agar and were non-tumorigenic in nude mice. To investigate if EBERs may protect the nasopharyngeal epithelial cells from apoptotic insults, we treated the EBER-expressing NP69 cells with a dsRNA analogue, poly(I).poly(C) (pIC), to activate PKR in cells and examined for their responses. Lower level of PKR phosphorylation and elevation of Bcl-2 were observed in EBER-expressing NP69 cells. In addition, other apoptotic markers including the cleaved forms of caspase-3 and poly(ADP)ribose polymerase (PARP) were found to be lower in EBER-expressing NP69 cells after treatment with pIC. Lower phosphorylation levels of p38 MAPK (mitogen-activated protein kinase) and c-jun were also observed in EBER-expressing NP cells. Our results suggest that EBER expression may confer an apoptotic-resistant phenotype in immortalized nasopharyngeal epithelial cells.

Establishment and characterization of a human first-trimester extravillous trophoblast cell line (TEV-1).

OBJECTIVE: Research into the biology of human trophoblast invasion has been hampered by a lack of in vitro models. The aim of this study was to establish and characterize a human extravillous trophoblast cell line from the first-trimester placenta. METHODS: Human papillomavirus type 16 (HPV16) E6/E7 genes were stably expressed in primary cultures of first-trimester placenta via a retroviral vector (pLXSN-E6/E7). Several clones were characterized for extravillous trophoblastic properties by reverse transcriptase polymerase chain reaction (RT-PCR), Western blotting, and immunocytochemistry. The activities of matrix metalloproteinase (MMP)-2 and MMP-9 were examined with gelatin zymography. One clone (TEV-1), which retains all the established criteria for extravillous trophoblasts, was used in microarray analysis with Stanford Human cDNA chip (41, 421 cDNA features) to examine the differential gene expression after treatment of transforming growth factor beta 1 (TGFbeta1). The responsive gene to TGFbeta1 treatment was confirmed by quantitative real-time PCR. RESULTS: The clonal TEV-1 has been passaged for more than 105 population doublings with no sign of senescence, the activation of telomerase at early passages, and a near-diploid karyotype. TEV-1 cells expressed cytokeratin 7, HLA-G (a histocompatibility antigen, class IB), and CD9 (the cluster of differentiation antigen 9), and secreted active MMP-2 and MMP-9. TGFbeta1 treatment altered the gene expression profile of TEV-1 cells with a marked up-regulation of insulin-like growth factor binding protein 3 (IGFBP3), which was confirmed by quantitative real-time PCR. In addition, the TEV-1 was nontumorigenic when injected into nude mice and unable to form colonies in soft agar. CONCLUSION: Phenotypic and biologic characteristics of TEV-1 were shown as the properties of extravillous trophoblasts; thus, the TEV-1 cell line may be used as a cell model in extravillous trophoblast studies.

MAD2-induced sensitization to vincristine is associated with mitotic arrest and Raf/Bcl-2 phosphorylation in nasopharyngeal carcinoma cells.

Mitotic arrest deficient 2 (MAD2) is thought to be a key component of the mitotic checkpoint, which ensures accurate chromosome segregation. Reduced expression of MAD2 protein is associated with mitotic checkpoint abrogation and chromosomal instability in certain types of human cancers. To explore the possibility of developing a novel strategy for the treatment of cancer based on selective killing of mitotic checkpoint-defective or -competent cells, here we have investigated the effect of MAD2 expression on cellular sensitivity to checkpoint-targeting anticancer drugs. We reintroduced MAD2 protein in a mitotic checkpoint-defective nasopharyngeal carcinoma cell line, CNE2, using an inducible expression vector. We found that overexpression of MAD2 led to an increased sensitivity to vincristine, which was accompanied by increased mitotic index and G2/M cell cycle arrest. In addition, increased phosphorylation of Raf, MEK1/2 and Bcl-2 was observed in MAD2-overexpressing cells in response to vincristine. Furthermore, inhibition of phosphorylation of MEK1/2 by its inhibitor PD098059 led to reduced sensitivity to vincristine, which was associated with decreased Bcl-2 phosphorylation. Our data suggest a role for MAD2 in the sensitization of cancer cells to certain mitotic checkpoint-targeting anticancer drugs.

Loss of heterozygosity and mutations are the major mechanisms of RB1 gene inactivation in Chinese with sporadic retinoblastoma.

We investigated sequence alternation, promoter methylation, and loss of heterozygosity (LOH) of the RB1 gene as possible mechanisms of its inactivation in retinoblastoma. In 42 Chinese patients with sporadic retinoblastoma, the promoter and entire coding region of RB1 were examined for sequence changes. Status of methylation of the CpG-rich island at the 5'end was determined by methylation specific PCR assay. We detected 15 RB1 mutations in 38% (16/42) of the retinoblastoma patients, among them 19% (8/42) were germ-line mutations. A total of nine novel mutations were identified: E54X, S114X, I126S, g73779insG, D718N, IVS2+1G>C, IVS14+1G>C, IVS21+1G>C, and a complex alteration g78177G>T/g78176insTT leading to 543X. Most of them are likely to affect the RB1large pocket domain through the production of truncated gene products. None of the DNA samples showed methylation at the RB1promoter. In 15 cases where both normal and cancerous retinoblastoma tissue specimens were available, allelic loss according to microsatellite markers within or distal to the RB1 locus was analyzed and immunohistological staining for RB1 expression performed. Among them, frequency of LOH at 13q14 was found to be high at 60% (9/15) with no segregation with unilateral tumors. All these nine tumors did not express RB1 protein, showing an association of LOH at the RB1 locus with its loss of expression in retinoblastoma. Our results indicate that the RB1 gene in sporadic retinoblastoma is commonly inactivated because of loss-of-function mutations and loss of heterozygosity but not by the epigenetic phenomenon of promoter hypermethylation.

Id-1 stimulates serum independent prostate cancer cell proliferation through inactivation of p16(INK4a)/pRB pathway.

It has been suggested that the helix-loop-helix protein Id-1 plays an important role in tumourigenesis in certain types of human cancer. Previously, we reported that Id-1 was up-regulated during sex hormone-induced prostate carcinogenesis in a Noble rat model (Ouyang et al. (2001) Carcinogenesis, 22, 965-973). In the present study, we investigated the direct effect of Id-1 expression on human prostate cancer cell proliferation by transfecting an Id-1 expression vector into a prostate cancer cell line LNCaP. Ten stable transfectant clones were isolated and the ectopic Id-1 expression resulted in both increased DNA synthesis rate and the percentage of S phase cells. To study the possible mechanisms involved in the Id-1 induced prostate cancer cell growth, we examined the expression of several factors responsible for G(1) to S phase progression. We found that Id-1 expression induced phosphorylation of RB and down-regulation of p16(INK4a) but not p21(Waf1)or p27(Kip1). Our results indicate that the Id-1 induced inactivation of p16(INK4a)/pRB pathway may be responsible for the increased cell proliferation in prostate cancer cells. Given the fact that both Id-1 over-expression and inactivation of p16(INK4a)/pRB are common events in prostate cancer, our results provide a possible mechanism on the molecular basis of prostate carcinogenesis.