Significance of scheduling on the cytotoxicity of radiation and cisplatin combination treatment in nasopharyngeal carcinoma cells

The use of cisplatin as a potential radiosensitizer in nasopharyngeal carcinoma (NPC) has produced encouraging results in clinical trials. In order to provide information on improving the design of clinical treatments, we investigated the effect of cisplatin dose, and the time interval and sequence between administration of cisplatin and radiation on cell survival of two NPC cell lines, CNE1 and SUNE1. When cisplatin was applied first, an exposure time of 24 h resulted in up to 2.6-fold increase in cell death and 7-fold increase in radiation effect (cell survival after cisplatin/cell survival after cisplatin plus radiation) in the cisplatin-radiation combination treatment compared to the cells treated with cisplatin for 4 h. When radiation was applied first, a shorter interval time of 4 h followed by cisplatin treatment resulted in up to 3-fold increase in cell death and a 3-fold enhanced radiation effect over longer time intervals of 24 h. By changing the order of radiation and cisplatin treatment alone, a 2-fold difference in radiation effect was observed. The differential cytotoxicity was partially explained by the alterations in cell cycle distribution. Our results indicate the importance of scheduling the radiation and cisplatin combination regimens on the survival of NPC cells.

Evidence of increased Id-1 expression and its role in cell proliferation in nasopharyngeal carcinoma cells

Inhibitor of differentiation or DNA binding (Id-1), a helix-loop-helix transcription factor, has recently been shown to inactivate the retinoblastoma (RB)/p16(INK4a) pathway through down-regulation of p16(INK4a) and increasing phosphorylation of RB in certain cell types. Nasopharyngeal carcinoma (NPC) is a common cancer in Hong Kong, and inactivation of the tumor suppressor RB at transcription level is a rare event in NPC. The objective of this study was to investigate the role of Id-1 in NPC cell proliferation and its expression in NPC samples. An NPC cell line, CNE1, was transfected with a retroviral vector containing a full-length Id-1 cDNA, and six stable transfectant clones were isolated with differential Id-1 expression levels. The effect of ectopic Id-1 expression on serum-independent cell growth, cell-cycle distribution, and expression of proteins associated with RB pathway was studied. The Id-1 expression in five NPC samples was also investigated using immunohistochemistry. Ectopic Id-1 expression in CNE1 cells resulted in an increase in serum-independent cell growth, percentage of cells in S phase, and phosphorylation of RB and cyclin-dependent kinase 2 proteins. In addition, immunohistochemical studies on NPC samples showed that expression of Id-1 was present in NPC cells but absent in normal tissues. This study demonstrates that Id-1 plays an important role in cell proliferation in NPC cells, and our results provide evidence for the first time of the significance of Id-1 expression in NPC cells and suggest a possible role of Id-1 expression in the inactivation of RB and development of NPC.

Over expression of ID-1 in prostate cancer

PURPOSE

The helix-loop-helix protein Id-1 serves to prevent basic helix-loop-helix transcription factors from binding to DNA, thus, inhibiting the transcription of differentiation associated genes. Over expression of Id-1 has been reported in certain tumors, such as breast, esophageal, pancreatic and medullary thyroid cancers. In Noble rats we have previously demonstrated that up-regulation of Id-1 is closely associated with the development of sex hormone induced prostate cancers. Therefore, we hypothesized that over expression of Id-1 would also occur in human prostate cancer and Id-1 protein may serve as a potential marker for prostate carcinogenesis. To test this hypothesis we analyzed Id-1 messenger RNA and protein expression by in situ hybridization and immunohistochemical study in human normal prostate, benign prostatic hyperplasia (BPH) and prostate cancer tissues.

MATERIALS AND METHODS

Pathological specimens were obtained from 19 patients with BPH and 47 with prostate carcinoma, representing a complete range of Gleason grades. A total of 12 normal prostate tissue specimens were used for comparison. Immunohistochemical study was performed using the polyclonal antibody against human Id-1 protein and an RNA probe was generated from Id-1 complementary DNA for in situ hybridization.

RESULTS

Negative to weak expression of Id-1 in normal prostate or BPH tissue was observed on immunohistochemical study and in situ hybridization. In contrast, all prostate cancer biopsies showed significant positive Id-1 expression in tumor cells at the messenger RNA and protein levels. Furthermore, Id-1 expression was stronger in poorly differentiated than in well differentiated carcinomas, suggesting that the level of Id-1 expression may be associated with tumor malignancy.

CONCLUSIONS

Our results suggest that over expression of Id-1 may have important roles in the development of prostate cancer. The potential use of Id-1 protein as a marker for prostate cancer should be further explored.

Establishment of two immortalized nasopharyngeal epithelial cell lines using SV40 large T and HPV16E6/E7 viral oncogenes

Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia, especially in southern China. One of the most striking features of this disease is its close relationship with Epstein-Barr Virus (EBV). However, to date there is no direct study on the mechanisms involved in the role of EBV in the tumorigenesis of NPC, largely due to lack of an experimental model. Available hypotheses on the association between EBV and NPC are generated from non-nasopharyngeal epithelial cell systems such as human keratinocytes or mouse epithelial cells, which may not truly represent the biological properties of nasopharyngeal epithelial (NP) cells. In this study, we report the establishment of two immortalized NP cell lines, NP69SV40T and NP39E6/E7, using SV40T and HPV16E6/E7 oncogenes. We found that NP60SV40T and NP39E6/E7 cell lines not only maintained many characteristics of normal NP cells (i.e. keratin profile and responsive to TGFbeta inhibition) but also highly responsive to one of the EBV encoded genes, LMP1. Comparative genome hybridization (CGH) analysis showed that these two cell lines contained multiple genetic alterations, some of which have been described in NPC. The immortalized NP cell lines are non-tumorigenic and exhibit anchorage-dependent growth. These cell lines may provide a possible cell model system for studying the mechanisms involved in the tumorigenesis of NPC.

Expression and localization of angiogenin in placenta: enhanced levels at term over first trimester villi

Human angiogenin, a 14-kDa non-glycosylated polypeptide with both angiogenic and ribonucleolytic activities, is implicated in angiogenesis, a complex process of proliferation and formation of new capillary blood vessels from existing blood vessels. Placental growth requires extensive angiogenesis, which develops its vascular structure in both fetal chorionic villi and maternal deciduas. In this study, we investigated the expression profiles of angiogenin in placental villi from early and late gestation at both mRNA and protein levels using explant cultures in vitro followed by RT-PCR, immunoblot, and immunohistochemical analyses. From functionally active placental explants, angiogenin was detected in conditioned media of all the samples from first trimester and term group. The mean levels of angiogenin produced by term villi were found to be 2.6-, 2.1-, and 2.2-fold higher (P < 0.01) than first trimester villi at 24, 48, and 72 hr of culture, respectively. Expression profiles of angiogenin from term and first trimester villi seem to agree with its mRNA levels and immunoblot analysis; the expression in term villi was twice that in first trimester villi. The presence of angiogenin in placental villi and upregulation of its production towards term indicate that angiogenin production by the placenta is specific to the developmental stage. In conclusion, the observed changes in the localization and mRNA expression of angiogenin during placental development raise the possibility that it is involved in morphological and angiogenic changes in this endocrine organ vital to the successful fetal outcome during pregnancy.

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.

The role of androgens in mammary carcinogenesis

Despite extensive research, the precise mechanism of mammary carcinogenesis is unknown. We have developed an animal model in which a high incidence of mammary cancer can be induced within a period of several months using a combination of testosterone (T) and 17beta-estradiol (E2) without the addition of carcinogens. The induced mammary tumours mimic closely the human breast cancer in terms of histopathology. Our results showed that the two sex hormones work synergistically to induce a higher incidence of mammary cancer than either hormone treatment alone. The dosage of T affects only the latency period of mammary cancer but not the final incidence. The results further showed that treatment of T, either alone or in combination with E2, there was overexpression of the androgen receptor (AR) in alveolar or ductal epithelial cells but not in stromal cells. Together with overexpression of AR in epithelial cells, there was an increase in perialveolar and interlobular connective tissue as well as a decrease in surrounding adipose tissue, despite the absence of AR in stromal cells. There was also an increase in proliferation rate of fibroblast-like cells in stroma. These changes were blocked by implantation of flutamide, an antiandrogen, indicating that androgens play a crucial role in the process. These findings highlight that the effect of androgens on the stroma, may be through a paracrine action of epithelial cells. The changes in the stroma may, in turn, promote mammary carcinogeneis in a reciprocal manner.

Down-regulation of Id-1 expression is associated with TGF beta 1-induced growth arrest in prostate epithelial cells

Transforming growth factor beta1 (TGF beta 1) plays important roles in the regulation of cell growth and differentiation in both normal and malignant prostate epithelial cells. Although certain pathways have been suggested, the mechanisms responsible for the action of TGF beta 1 are not well understood. In the present study, using a human papilloma virus 16 E6/E7 immortalized prostate epithelial cell line, HPr-1, we report that TGF beta 1 was able to suppress the expression of Id-1, a helix-loop-helix (HLH) protein, which plays important roles in the inhibition of cell differentiation and growth arrest. In addition, a decrease at both Id-1 mRNA and protein expression levels was associated with TGF beta 1-induced growth arrest and differentiation, indicating that Id-1 may be involved in TGF beta 1 signaling pathway. The fact that up-regulation of p21(WAF1), one of the downstream effectors of Id-1, was observed after exposure to TGF beta 1 further indicates the involvement of Id-1 in the TGF beta 1-induced growth arrest in HPr-1 cells. However, increased expression of p27(KIP1) was also observed in the TGF beta 1-treated cells, suggesting that in addition to down-regulation of Id-1, other factors may be involved in the TGF beta 1-induced cell growth arrest and differentiation in prostate epithelial cells. Our results provide evidence for the first time that TGF beta 1 may be one of the upstream regulators of Id-1.

The effect of flutamide and tamoxifen on sex hormone-induced mammary carcinogenesis and pituitary adenoma

We have established a female Noble rat model to explore the mechanisms of hormonal mammary carcinogenesis. Based on the previous finding that the dose of testosterone affects only the latency period of mammary cancer, not the final incidence and that androgen upregulates apoptotic activity in pre-malignant mammary glands, we hypothesised that estrogen is the initiator and androgen the promoter for hormonal mammary carcinogenesis of the rats. In the present study, rats were treated with the sex hormones together with flutamide and tamoxifen for both short term (7 and 13 weeks) and long term (12 months) durations. We showed that tamoxifen could totally inhibit mammary carcinogenesis while flutamide cause a delay and reduction in tumour incidence in the 12 months treatment term. Blocking effect of flutamide and tamoxifen on T + E2 (testosterone and 17beta-estradiol) short-terms treatment was demonstrated by the similar histological changes identified in the mammary glands of the T + E2 and drug treated rats to that of the age matched E2 and T controls, respectively. These findings give further support for the role of estrogen and androgen in mammary carcinogenesis. Autopsy of the tumour bearing rats showed presence of pituitary macroadenoma causing compression and atrophy of the brain stem. Immunohistochemical staining of these adenomas showed a predominance of prolactin-secreting cells. Serum assay also showed a corresponding increase in circulatory prolactin level. Tamoxifen was also effective in blocking the formation of pituitary adenoma in the sex hormone treated rats. Pituitary size and level of prolactin were higher in the T + E2 + flutamide group than the T + E2 group in both short-term and long-term treatments. It suggests that testosterone may have a role in counteracting estradiol stimulation on the pituitary lactotropes although it is synergistic to estrogen in mammary carcinogenesis. Pituitary adenomas were found in all rats that developed mammary adenocarcinoma but not vice versa suggesting that prolactin level elevation alone cannot lead to mammary tumorigenesis. The animal model, in addition to mammary carcinogenesis, may be useful for investigation of anti-estrogen therapy in pituitary adenomas.

Cervical carcinoma: MR imaging with integrated endorectal/phased-array coils: a pilot study

The purpose of this study was to investigate the value of using MRI with integrated endorectal/phased-array coils for the staging and determination of the extent of cervical carcinoma. Twenty-two consecutive patients with biopsy-proven cervical carcinoma underwent MRI with integrated endorectal/phased-array coils before treatment. Magnetic resonance imaging was compared with clinical staging using surgical and pathological results as the gold standard. Eighteen of 22 patients underwent surgery. Seventeen of the 18 patients were correctly staged using an integrated endorectal/phased-array MRI with an overall staging accuracy of 94%. Fourteen of the 18 patients had a correct clinical staging with an overall staging accuracy of 78%. The overall accuracy of pelvic lymph node metastasis detection was 89% on MRI. These data showed that MRI using integrated endorectal/phased-array coils was more accurate than the clinical approach for the staging of cervical carcinoma. Magnetic resonance imaging using integrated endorectal/phased-array coils is a highly promising modality for detecting and staging cervical carcinomas.

Effect of p53 on centrosome amplification in prostate cancer cells

Chromosomal instability (CIN) is one of the common features in prostate cancer, especially in advanced stages. Recently, the involvement of p53 in CIN through the regulation of centrosome amplification has been proposed in certain tumor types. In this study, we investigated the relationship between p53 and centrosome amplification in prostate cancer cells. Increased centrosome number and size were observed in DU145 and PC3 containing nonfunctional p53 compared to LNCap which expressed wild-type p53. Transfection of p53 into PC3 cells resulted in a decreased cell growth rate, G2/M arrest and decreased centrosome abnormalities. We provide the first evidence on a correlation between loss of p53 function and centrosome amplification in prostate cancer cells. Our results indicate that p53 may play a role in the regulation of centrosome amplification and loss of p53 may be one of the mechanisms involving CIN in prostate cancer cells.

Intramedullary high signal intensity on T2-weighted MR images in cervical spondylotic myelopathy: prediction of prognosis with type of intensity

PURPOSE

To examine whether the different appearances of intramedullary high signal intensity (SI) on T2-weighted MR images in cervical spondylotic myelopathy are related to differences in surgical prognosis.

MATERIALS AND METHODS

The magnetic resonance (MR) findings and Japanese Orthopedic Association (JOA) score of 64 cervical spondylotic myelopathy patients, who underwent decompression surgery, were evaluated. SIs were classified as type 0 if no intramedullary high SI on T2-weighted MR images was noted, type 1 if a predominantly (>50%) faint and fuzzy border of high SI was noted, or type 2 if a predominantly (>50%) intense and well-defined border of high SI was noted. Postoperative JOA scoring and MR imaging were also performed 6 months after surgery. Recovery ratios were calculated.

RESULTS

There were 20 type 0, 23 type 1, and 21 type 2 cases. Statistical analyses showed no significant difference in age, sex, cervical curvature, and preoperative JOA score between the three groups. Statistical analyses of the recovery ratio showed significantly poor prognosis of type 2 compared with type 1 (P < .001) and type 0 (P =.001), but no difference between types 0 and 1 (P = .317). After controlling for factors of age, sex, preoperative JOA score, cervical curvature, and cord compression ratio, analysis of covariance showed the same result.

CONCLUSION

Type 1 intramedullary high SI on T2-weighted MR images indicates a better surgical outcome than does type 2.

E-cadherin expression is commonly downregulated by CpG island hypermethylation in esophageal carcinoma cells

E-cadherin, a cell adhesion molecule, is regarded as an invasion-suppressor molecule and a prognostic marker in many types of human cancers. Downregulation of E-cadherin is common in esophageal carcinoma and is associated with an increase in invasive and metastatic potential. To study the mechanisms responsible for inactivation of this gene in esophageal squamous cell carcinoma (ESCC), we investigated the methylation status around the 5' promoter region of E-cadherin gene of six ESCC cell lines by methylation-specific polymerase chain reaction, and compared it with E-cadherin protein and mRNA expression. We also studied the methylation status of 20 ESCC clinical specimens. Methylation was noted in four of the six cell lines (one fully methylated and three partially methylated). The completely methylated cell line lacked E-cadherin protein expression and mRNA transcription. E-cadherin expression and transcription were reduced in a partially methylated cell line but preserved in the other partially methylated cell lines. Treatment of E-cadherin-negative carcinoma cells with the demethylating agent, 5-aza-2'-deoxycytidine, induced re-expression of the gene. A high frequency of methylation (16/20, 80%) was also noted in the 20 ESCC clinical samples. Our results indicate that 5' CpG island methylation is common in esophageal carcinoma and may play an important role in downregulation of E-cadherin.

Combine-ARMS: a rapid and cost-effective protocol for molecular characterization of beta-thalassemia in Malaysia

Beta-thalassemia major patients have chronic anemia and are dependent on blood transfusions to sustain life. Molecular characterization and prenatal diagnosis of beta3-thalassemia is essential in Malaysia because about 4.5% of the population are heterozygous carriers for beta-thalassemia. The high percentage of compound heterozygosity (47.62%) found in beta-thalassemia major patients in the Thalassaemia Registry, University of Malaya Medical Centre (UMMC), Malaysia, also supports a need for rapid, economical, and sensitive protocols for the detection of beta-thalassemia mutations. Molecular characterization of beta-thalassemia mutations in Malaysia is currently carried out using ARMS, which detects a single beta-thalassemia mutation per PCR reaction. We developed and evaluated Combine amplification refractory mutation system (C-ARMS) techniques for efficient molecular detection of two to three beta-thalassemia mutations in a single PCR reaction. Three C-ARMS protocols were evaluated and established for molecular characterization of common beta-thalassemia mutations in the Malay and Chinese ethnic groups in Malaysia. Two C-ARMS protocols (cd 41-42/IVSII #654 and -29/cd 71-72) detected the beta-thalassemia mutations in 74.98% of the Chinese patients studied. The CARMS for cd 41-42/IVSII #654 detected beta-thalassemia mutations in 72% of the Chinese families. C-ARMS for cd 41-42/IVSI #5/cd 17 allowed detection of beta-thalassemia mutations in 36.53% of beta-thalassemia in the Malay patients. C-ARMS for cd 41-42/IVSI #5/cd 17 detected beta-thalassemia in 45.54% of the Chinese patients. We conclude that C-ARMS with the ability to detect two to three mutations in a single reaction provides more rapid and cost-effective protocols for beta-thalassemia prenatal diagnosis and molecular analysis programs in Malaysia.

Nonrandom chromosomal imbalances in human ovarian surface epithelial cells immortalized by HPV16-E6E7 viral oncogenes

We had previously immortalized human ovarian surface epithelial (HOSE) cells using HPV16E6E7 ORFs. In order to identify crucial genetic events involved during cell immortalization, the genomic profile of immortalization of five HOSE cell lines was analyzed by comparative genomic hybridization. Our results showed that chromosomal imbalance was common in HOSE cells after immortalization. The common chromosomal imbalances identified in immortal HOSE cells are: +19q13.1 (5/5 lines), -13q12 approximately qter (4/5 lines), +5q15 approximately q33 (3/5 lines), +20q11.2 approximately q13.2 (3/5 lines) and -22q11.2 approximately qter (3/5 lines). Other chromosomal imbalances, which were detected in two of the five immortal HOSE cell lines, included gains on chromosome 1 and 11q12 approximately q13, and losses on 2p, 4q, 8p, 10p and 11q14 approximately qter. The chromosomal imbalances observed in HOSE cells before immortalization include -8pter approximately p11.2, -11q23 approximately qter, -13q12 approximately qter and +19 which may represent early genetic events during cell immortalization. The genomic profile was examined in one HOSE cell line (HOSE 6-3) at various stages of immortalization. The genomic profiles of HOSE 6-3 cells after crisis were largely stable. A few additional chromosomal imbalances were detected in the immortalized HOSE cells after an extensive culture period including +11pter approximately q23, -15q23 approximately qter, and +17q12 approximately qter. Identification of nonrandom chromosomal imbalance in immortalized HOSE cells may facilitate the identification of specific chromosomes harboring genes involved in the immortalization of human ovarian surface epithelial cells.

MAPD--an objective way to select mAs for paediatric brain CT

CT is an advanced imaging modality, but the imaging parameters are normally selected subjectively. For standard head examinations, most of the parameters used are consistent amongst different centres, with the exception of large variations in the selection of the tube current-exposure time product (mAs). As a result, CT images may contain unacceptable levels of noise, or the patient may receive excessive radiation. In this study, the maximum anteroposterior diameter (MAPD) was shown to be a good criterion for mAs selection, and could be measured in a pilot view. 200 paediatric brain CT studies were randomly selected to determine the MAPD at the mid brain level. With knowledge of MAPD distribution, a phantom study was performed to determine the relationship between MAPD and the mAs required for consistent and acceptable image noise. It was found that the required mAs increased linearly with MAPD. Assuming the manufacturer's recommended value is "appropriate" for the average MAPD, the appropriate mAs value could be estimated. Using this method, appropriate mAs values were calculated retrospectively for a group of 240 randomly selected paediatric brain CT studies and compared with the actual mAs subjectively determined by the radiographer. Although their average values were similar, the difference between the calculated and actual values deviated markedly in some cases. When the actual mAs was smaller than the calculated value, higher image noise was observed. However, reduction of image noise was barely observed when the applied mAs was larger than the calculated value. Thus, this method is more objective and appropriate for determination of the mAs value for paediatric brain CT than the traditional subjective method.

Identification of downstream target genes of latent membrane protein 1 in nasopharyngeal carcinoma cells by suppression subtractive hybridization

Nasopharyngeal carcinoma (NPC) is a common cancer in Southern China and is closely associated with infection of Epstein-Barr virus (EBV). The EBV encoded latent membrane protein 1 (LMP1) is frequently detected in NPC and may play a role in its pathogenesis. Previous studies have shown that LMP1 transformed rodent fibroblasts and altered growth properties in B cells and epithelial cells. However, the pathological role of LMP1 in NPC cells is still poorly understood. In order to investigate the downstream target genes of LMP1 in NPC cells, suppression subtractive hybridization was used to clone and identify the genes differentially expressed in a LMP1 expressing NPC cell line, CNE-2. Two subtractive cDNA libraries were constructed: one enriched for the genes upregulated by LMP1 and one was for the genes downregulated by LMP1. A total of 192 clones were screened by reverse Northern blotting. Fourteen of them were confirmed to be overexpressed while eight of them were suppressed. The upregulation of integrin alpha6, laminin 5gamma2, TAP1 and downregulation of p54nrb, RACK1 and p66Shc were further confirmed in three sets of LMP1 expressing NPC cell lines. The expression profiles of differentially expressed genes identified in this study suggest a role of LMP1 in promotion of cell survival and facilitation of tumor invasion.

Imaging features of pancreatoblastoma

BACKGROUND

Pancreatoblastoma is a rare tumour of childhood. Reports of the imaging appearances are limited.

OBJECTIVE

To define the imaging features of pancreatoblastoma by analysis of four previously unreported cases and review of the literature.

MATERIALS AND METHODS

Findings at CT (n = 4), US (n = 3) and MRI (n = 2) were retrospectively reviewed in four patients with pancreatoblastoma. A Medline search was performed to identify relevant literature.

RESULTS

Pancreatoblastoma arises most frequently in the body and/or tail, or involves the entire pancreas. Ultrasonography, CT and MRI show variable imaging features, but should in most cases permit preoperative distinction of pancreatoblastoma from other tumours that occur in this region in infancy and childhood. Detection of metastases in the liver, lymph nodes and peritoneal cavity is not significantly better with any one of these three modalities.

CONCLUSION

Preoperative imaging with US, CT and/or MRI will usually suggest a correct diagnosis of pancreatoblastoma. Contrary to previous reports, the tumour arises in the pancreatic head in a minority of cases.

Up-regulation of TRPM-2, MMP-7 and ID-1 during sex hormone-induced prostate carcinogenesis in the Noble rat

Prostate cancer is the most frequently diagnosed malignancy in the Western world and changes in the ratio of testosterone and estrogens with advancing age is one of the potential risk factors in the development of this disease. However, the molecular mechanisms associated with hormone imbalance in prostate carcinogenesis are poorly understood. In this study we induced a high incidence of prostate hyperplasia, dysplasia and adenocarcinoma in the Noble rat using a combination of testosterone and estradiol-17beta. Using this animal model, we studied the gene expression profile during sex hormone-induced prostate carcinogenesis using a cDNA array technique; the results were further confirmed by RT-PCR, western blotting and immunohistochemical analyses. We found up-regulation of TRPM-2 (testosterone-repressed prostatic message-2), MMP-7 (matrix metalloproteinase-7) and Id-1 (inhibitor of differentiation or DNA binding) during development of sex hormone-induced prostate cancer. Increased expression of TRPM-2 and MMP-7 was observed in both premalignant and malignant tissues after sex hormone treatment, indicating their role in the early stages of hormone response and prostate cancer development. In contrast, Id-1 was expressed at relatively low levels in all premalignant samples but increased in malignant cells, suggesting its potential roles as a biomarker for prostate cancer cells. Furthermore, expression of Id-1 appeared to be stronger in poorly differentiated lesions than in well-differentiated carcinomas, suggesting that the levels of Id-1 expression may be correlated with the malignancy of tumors. Our results provide the first evidence of up-regulation of TRPM-2, MMP-7 and Id-1 during sex hormone-induced prostate carcinogenesis and strongly suggest their association with the development of prostate cancer.

The prostate gland and prostate carcinogenesis

Despite extensive research, the mechanisms of prostate carcinogenesis are not well understood. The slow progress in this area is due, at least in part, to lack of a suitable animal model for prostate carcinogenesis. We have developed an animal model, based on the existing sex hormone-induced prostate carcinogenesis in the Noble rat, by substantially increasing the dosage of testosterone while keeping the level of estrogen unchanged. Using the modified method of combination of testosterone and estradiol-17beta (T+E2), it has been shown in Noble rats that prostate carcinogenesis followed a multi-step process involving hyperplasia, dysplasia, and carcinoma. We have demonstrated the importance of TGF-alpha, TGF-beta1 and bFGF in the development of prostate carcinogenesis. This study also established the roles of VEGF and IGF-1, initially as paracrine factors in epithelial-stromal interactions during the process of carcinogenesis and subsequently switching over to an autocrine mode during the establishment of carcinoma.

Periaortic contrast medium extravasation on chest CT in traumatic aortic injury: a sign for immediate thoracotomy

Traumatic aortic injury (TAI) after blunt chest trauma is potentially a lethal condition. The injury must be diagnosed promptly and accurately. Evaluation for traumatic aortic injury begins with an assessment of mechanism of injury, a physical examination and chest radiography. In recent years, chest computed tomography (CT) has been advocated as a better screening tool to detect TAI but there is still controversial over the confirmatory diagnostic value of CT. For hemodynamically unstable patients in whom chest CT had shown direct sign of aortic injury and with periaortic contrast medium extravasation, we advocate that these patients should be operated on immediately without aortogram to avoid unnecessary delay. Herein, we describe a case of TAI with direct signs and periaortic contrast extravasation and discuss if chest CT can substitute an aortogram as a diagnostic tool when direct signs of TAI are revealed.

Development of an analytical technique and stability evaluation of 143 C3-C12 volatile organic compounds in Summa canisters by gas chromatography-mass spectrometry

A technique using Summa canisters with cryogenic preconcentration and gas chromatographic-mass spectrometric (GC-MS) detection was developed to determine 143 C3-C12 volatile organic compounds (VOCs) including alkanes, alkenes, aromatics and halohydrocarbons in ambient and indoor air. The method detection limits and practical quantification limits were sensitive at 0.02 and 0.10 ppbv, respectively, and the method precision and accuracy were also satisfactory. The stability of C3-C12 VOC standards at ppbv levels under elevated pressure in canisters was assessed over various time intervals (from 1 week to 4 months after preparation) and most of the compounds were found to be acceptably stable with a mean recovery of 85.6 +/- 9.9% during the course of a 4-month study. However, a small fraction (approximately 6%) of the compounds, including two halohydrocarbons (bromotrichloromethane and benzyl chloride) and six alkenes (2-methylbuta-1,3-diene (isoprene), cis-4-methylpent-2-ene, cis-3-methylpent-2-ene, hept-1-ene, oct-1-ene and styrene) displayed relatively low recoveries in the range 34.6-67.9%. The loss of these compounds is most probably caused by their physical adherence to the active sites of the canister surface, chemical decomposition and/or reactions with other species. The results indicated that one must be cautious in attempting to measure these compounds owing to their instability in canisters. Overall, this analytical technique, which has been used for the determination of the VOCs under study in the toxic air pollutant monitoring network administered by the HKSAR Government, was amenable to the measurement of airborne VOCs collected both outside and inside a semi-confined car park in the present study.

Liver transplantation in rats using small-for-size grafts: a study of hemodynamic and morphological changes

BACKGROUND

Damage to a small-for-size liver graft after reperfusion is frequently observed but the mechanism of injury remains unclear.

HYPOTHESIS

Injury to a small-for-size liver graft is related to the changes of portal pressure and blood flow.

MAIN OUTCOME MEASURES

Survival rates, portal hemodynamics, microcirculatory changes, and morphological changes (by light microscopy and electron microscopy).

SETTING

A rat model of nonarterialized orthotopic liver transplantation comparing 2 groups of rats transplanted with whole grafts (100% of recipient liver weight) and small-for-size grafts (30% of recipient liver weight).

RESULTS

Median survival of the rats with small-for-size grafts was 30 hours (range, 27-37 hours). During the first 15 minutes after reperfusion, mean arterial pressure of the small-for-size graft group was significantly lower than that of the whole graft group (10-minute: 100 vs 132 mm Hg, P =.04; 15-minute: 96 vs 127 mm Hg, P =.04). Portal pressure (in centimeters of water) of the small-for-size graft group was significantly higher in the first 20 minutes after reperfusion than the level before the anhepatic phase (5-minute: 15.1 vs 9.3, P =.02; 10-minute: 16.1 vs 9.3, P =.03; 15-minute, 13.5 vs 9.3, P =.03; 20-minute: 13.4 vs 9.3, P =.03) and was significantly higher than that of the whole graft group in the first 10 minutes after reperfusion (5-minute: 15.1 vs 9.6, P =.02; 10-minute: 16.1 vs 10.3, P =.04). Hepatic microcirculatory blood flow (in milliliters per minute per 100 g) was also significantly higher in the small-for-size graft group during the first 40 minutes after reperfusion (5-minute: 16.3 vs 9.3, P =.02; 10-minute: 14.9 vs 6.6, P =.02; 15-minute: 14.8 vs 5.5, P =.02; 20-minute: 13.1 vs 7.0, P =.02; 30-minute: 13.2 vs 8.8, P =.04; 40-minute: 14.6 vs 7.1, P =.02). Light and electron microscopy showed normal morphological features of whole graft up to 24 hours after reperfusion. The small-for-size graft, however, showed sinusoidal congestion, tremendous swelling of mitochondria of hepatocytes, irregular large gap of sinusoidal lining cells, and collapse of the space of Disse.

CONCLUSIONS

In a rat model, the portal hemodynamic changes in small-for-size grafts are transient. Progressive damage of the graft may result from microcirculatory failure due to irreversible endothelial injury after reperfusion.