Identification of distinct slow mode of reversible adaptation of pancreatic ductal adenocarcinoma to the prolonged acidic pH microenvironment

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is the most common pancreatic neoplasm with high metastatic potential and poor clinical outcome. Like other solid tumors, PDAC in the early stages is often asymptomatic, and grows very slowly under a distinct acidic pHe (extracellular pH) microenvironment. However, most previous studies have only reported the fate of cancerous cells upon cursory exposure to acidic pHe conditions. Little is known about how solid tumors-such as the lethal PDAC originating within the pancreatic duct-acinar system that secretes alkaline fluids-evolve to withstand and adapt to the prolonged acidotic microenvironmental stress.

METHODS

Representative PDAC cells were exposed to various biologically relevant periods of extracellular acidity. The time effects of acidic pHe stress were determined with respect to tumor cell proliferation, phenotypic regulation, autophagic control, metabolic plasticity, mitochondrial network dynamics, and metastatic potentials.

RESULTS

Unlike previous short-term analyses, we found that the acidosis-mediated autophagy occurred mainly as an early stress response but not for later adaptation to microenvironmental acidification. Rather, PDAC cells use a distinct and lengthy process of reversible adaptive plasticity centered on the early fast and later slow mitochondrial network dynamics and metabolic adjustment. This regulates their acute responses and chronic adaptations to the acidic pHe microenvironment. A more malignant state with increased migratory and invasive potentials in long-term acidosis-adapted PDAC cells was obtained with key regulatory molecules being closely related to overall patient survival. Finally, the identification of 34 acidic pHe-related genes could be potential targets for the development of diagnosis and treatment against PDAC.

CONCLUSIONS

Our study offers a novel mechanism of early rapid response and late reversible adaptation of PDAC cells to the stress of extracellular acidosis. The presence of this distinctive yet slow mode of machinery fills an important knowledge gap in how solid tumor cells sense, respond, reprogram, and ultimately adapt to the persistent microenvironmental acidification.

Assessment of Brain Functional Activity Using a Miniaturized Head-Mounted Scanning Photoacoustic Imaging System in Awake and Freely Moving Rats

Understanding the relationship between brain function and natural behavior remains a significant challenge in neuroscience because there are very few convincing imaging/recording tools available for the evaluation of awake and freely moving animals. Here, we employed a miniaturized head-mounted scanning photoacoustic imaging (hmPAI) system to image real-time cortical dynamics. A compact photoacoustic (PA) probe based on four in-house optical fiber pads and a single custom-made 48-MHz focused ultrasound transducer was designed to enable focused dark-field PA imaging, and miniature linear motors were included to enable two-dimensional (2D) scanning. The total dimensions and weight of the proposed hmPAI system are only approximately 50 × 64 × 48 mm and 58.7 g (excluding cables). Our ex vivo phantom experimental tests revealed that a spatial resolution of approximately 0.225 mm could be achieved at a depth of 9 mm. Our in vivo results further revealed that the diameters of cortical vessels draining into the superior sagittal sinus (SSS) could be clearly imaged and continuously observed in both anesthetized rats and awake, freely moving rats. Statistical analysis showed that the full width at half maximum (FWHM) of the PA A-line signals (relative to the blood vessel diameter) was significantly increased in the selected SSS-drained cortical vessels of awake rats (0.58 ± 0.17 mm) compared with those of anesthetized rats (0.31 ± 0.09 mm) (p < 0.01, paired t-test). In addition, the number of pixels in PA B-scan images (relative to the cerebral blood volume (CBV)) was also significantly increased in the selected SSS-drained blood vessels of awake rats (107.66 ± 23.02 pixels) compared with those of anesthetized rats (81.99 ± 21.52 pixels) (p < 0.01, paired t-test). This outcome may result from a more active brain in awake rats than in anesthetized rats, which caused cerebral blood vessels to transport more blood to meet the increased nutrient demand of the tissue, resulting in an obvious increase in blood vessel volume. This hmPAI system was further validated for utility in the brains of awake and freely moving rats, showing that their natural behavior was unimpaired during vascular imaging, thereby providing novel opportunities for studies of behavior, cognition, and preclinical models of brain diseases.

A clamp-like orientation of basic residues set in a parallelogram is essential for heparin binding

While the majority of studies have focused on the biological roles of heparin-binding proteins, relatively little is known about their key residues and structural elements responsible for heparin interaction. In this study, we employed the IgG-binding domain B1 of Streptococcal protein G as a miniature scaffold to investigate how certain positively charged residues within the β-sheet conformation become favorable for heparin binding. By performing a series of arginine substitution mutations followed by gain-of-heparin-binding analysis, we deduced that a clamp-like orientation with discontinuous basic residues separated by ~ 5 Å with ~ 100° interior angle is advantageous for high heparin affinity.

AKT3 promotes prostate cancer proliferation cells through regulation of Akt, B-Raf, and TSC1/TSC2

The qRT-PCR analysis of 139 clinical samples and analysis of 150 on-line database clinical samples indicated that AKT3 mRNA expression level was elevated in primary prostate tumors. Immunohistochemical staining of 65 clinical samples revealed that AKT3 protein expression was higher in prostate tumors of stage I, II, III as compared to nearby normal tissues. Plasmid overexpression of AKT3 promoted cell proliferation of LNCaP, PC-3, DU-145, and CA-HPV-10 human prostate cancer (PCa) cells, while knockdown of AKT3 by siRNA reduced cell proliferation. Overexpression of AKT3 increased the protein expression of total AKT, phospho-AKT S473, phospho-AKT T308, B-Raf, c-Myc, Skp2, cyclin E, GSK3β, phospho-GSK3β S9, phospho-mTOR S2448, and phospho-p70S6K T421/S424, but decreased TSC1 (tuberous sclerosis 1) and TSC2 (tuberous Sclerosis Complex 2) proteins in PC-3 PCa cells. Overexpression of AKT3 also increased protein abundance of phospho-AKT S473, phospho-AKT T308, and B-Raf but decreased expression of TSC1 and TSC2 proteins in LNCaP, DU-145, and CA-HPV-10 PCa cells. Oncomine datasets analysis suggested that AKT3 mRNA level was positively correlated to BRAF. Knockdown of AKT3 in DU-145 cells with siRNA increased the sensitivity of DU-145 cells to B-Raf inhibitor treatment. Knockdown of TSC1 or TSC2 promoted the proliferation of PCa cells. Our observations implied that AKT3 may be a potential therapeutic target for PCa treatment.

Abstract 1128: TET1-mediated epigenetic reprogramming switches metabolism and promotes malignant phenotypes of ovarian cancer

Epigenetic dysregulation is one of the mechanisms involved in ovarian cancer carcinogenesis. Recently identified a new epigenetic modulator ten-eleven translocation protein 1 (TET1), a DNA dioxygenase which is believed in DNA demethylation through a 5-methylcytosine to 5-hydroxymethylcytosine (5hmC) conversion, plays an important role in regulating self-renewal and specification in embryonic stem cells. In addition, it works as a tumor suppressor gene by inhibition of cell invasion, migration and tumor growth in breast and prostate cancer. However, the role of TET1 in ovarian cancer remains unknown. Thus we examed the expression level of TET1 in ovarian cancer tissues. We found that TET1 expression level correlated with cancer staging (p = 0.03) in 88 ovarian cancer from our biobank and poor survival (p = 0.012) in TCGA database. High expression of TET1 was observed in advanced stage, high-grade primary tumor specimens in comparison with normal ovarian surface epithelium (OSE) brushings (p = 0.0005) by NCBI database (GSE18520). These results suggested that TET1 may play some roles in ovarian cancer development, which is different from those previously published in other cancers. To study the function of TET1 in ovarian cancer, we generated TET1 over-expressing and knockdown cell lines model, the expression level and enzymatic activities of TET1 were confirmed by real time PCR, western and 5hmC stain. Here we found that TET1 increases the abilities of cell migration, anchorage-independent growth and promotes tumor growth. In addition, TET1 actives cancer stem markers and enhances the abilities of spheroid formation. Ovarian cancer stem cells (OCSCs) from cell line express high level of TET1 while the differentiated progenies suppress TET1 expression. Moreover, seven of eight patient-derived OCSCs revealed high expressing of TET1 in comparison with its parental cancer cells by quantitative PCR. To further examine the TET1 regulation network, we combined the expression array and MethCap-seq to analyze the epigomic changes. We found that a cluster of target genes which were up-regulated through DNA demethylation were enzymes responsible for oxidative phosphorylation. We investigated metabolic status by Extracellular Flux Analyzer (seahourse) on the TET1-overexpressing cells. Compared with control cells, TET1-overexpressing cells revealed 1.7 fold (p = 0.011) increase of oxygen consumption rate (OCR); while the extracellular acidification rate (ECAR) showed no difference (p = 0.856). This bioenergetic metabolism shift may be due to demethylation of subunits of mitochondria complexs. Taken together, TET1 reprograms the epigenome, shifts the metabolism, increases the malignant phenotypes and confers a poor prognosis of ovarian cancer. Targeting mitochondria on TET1-expressing ovarian cancer patients may provide a new way of personalized therapy.

Citation Format: Lin-yu Chen, Rui-Lan Huang, Pearlly S. Yan, Tien-Shuo Huang, Yu-Ping Liao, Jian-Liang Chou, Jora M.J. Lin, Tai-Kuang Chao, Michael W.Y. Chan, Wun-Shaing Wayne Chang, Hung-Cheng Lai. TET1-mediated epigenetic reprogramming switches metabolism and promotes malignant phenotypes of ovarian cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1128. doi:10.1158/1538-7445.AM2015-1128

Abstract 4982: Characterization of novel α-ketoamide derivatives as potent inhibitors against cathepsin S induced by acidic extracellular pH in pancreatic cancer cells

Extracellular acidification is known to be a driving force in pancreatic cancer growth and metastasis. Thus, manipulation of acidic peritumoral pH or blockage of key proteins stimulated by acidic extracellular microenvironment may offer considerable potential for pancreatic cancer therapy. Cathepsin S, also known as CTSS or CatS, is a critical proteolytic enzyme found to be up-regulated in malignant cells and secreted into the extracellular milieu to degrade surrounding matrix components. By examining the effect of low pH (6.7) on various pancreatic tumor cell lines, we detected a consistently increased CTSS expression associated with augmented cell migration and invasion. Other features such as CTSS-mediated proteolysis and ECM degradation were also observed under mildly acidic condition. Based on these findings, we designed and synthesized some new small molecules bearing an α-ketoamide warhead to evaluate their ability to inhibit CTSS. Kinetic study revealed these compound inhibitors possess very low Ki values and high specificity against target CTSS enzyme. Further in vitro and in vivo analyses demonstrated these agents not only could protect fibronectin from CTSS-mediated degradation but also induce tumor cell autophagy under extracellular acidification. Together these results indicate the potential of α-ketoamide derivatives as antitumor agents against pancreatic cancer.

Citation Format: Wun-Shaing Wayne Chang, Tzu-Yuan Chang, Tzu-Chin Wu, Chien-Yu Liao, Chun-Cheng Lin. Characterization of novel α-ketoamide derivatives as potent inhibitors against cathepsin S induced by acidic extracellular pH in pancreatic cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4982. doi:10.1158/1538-7445.AM2014-4982

Targeting cathepsin S induces tumor cell autophagy via the EGFR-ERK signaling pathway

Cathepsin S is a cellular cysteine protease, which is frequently over-expressed in human cancer cells and plays important role in tumor metastasis. However, the role of cathepsin S in regulating cancer cell survival and death remains undefined. The aim of this study was to determine whether targeting cathepsin S could induce autophagy/apoptosis in cancer cells. In this study, we demonstrated that targeting cathepsin S by either specific small molecular inhibitors or cathepsin S siRNA induced autophagy and subsequent apoptosis in human cancer cells, and the induction of autophagy was dependent on the phosphorylation of EGFR and activation of the EGFR-related ERK/MAPK-signaling pathway. In conclusion, the current study reveals that cathepsin S plays an important role in the regulation of cell autophagy through interference with the EGFR-ERK/MAPK-signaling pathway.

Suppression of the invasion and migration of cancer cells by SERPINB family genes and their derived peptides

Apart from SERPINB2 and SERPINB5, the roles of the remaining 13 members of the human SERPINB family in cancer metastasis are still unknown. In the present study, we demonstrated that most of these genes are differentially expressed in tumor tissues compared to matched normal tissues from lung or breast cancer patients. Overexpression of each SERPINB gene effectively suppressed the invasiveness and motility of malignant cancer cells. Among all of the genes, the SERPINB1, SERPINB5 and SERPINB7 genes were more potent, and the inhibitory effect was further enhanced by co-expression of any two of them. In addition, single treatment of the synthetic peptides corresponding to the P5-P5' sequences of the reactive center loop (RCL) of SERPINB1, SERPINB5 or SERPINB7 markedly suppressed the invasive and migratory properties of the cancer cells in a dose-dependent manner. More significantly, combination treatment of these peptides in cancer cells further improved the suppressive effect by 20-40%. Here, we determined the expression of all SERPINB family members in lung and breast cancer patients, and identified those members with potent inhibitory ability toward invasion and migration, and designed RCL-derived peptides to suppress the malignancy of cancer cells. Forced re-expression of these anti-invasive SERPINB genes or application of the SERPINB RCL-peptides may provide a reasonable strategy against lethal cancer metastasis.

Abstract 2864: Targeting cathepsin S induces tumor cell autophagy via the EGFR-ERK signaling pathway

Cathepsin S is a vital cellular cysteine protease that is frequently amplified and over-expressed in various human cancers. In this study, we report that targeting cathpesin S could induce tumor cell autophagy via the EGFR-ERK signaling pathway. Cancer cells treated with cathepsin S inhibitors [α-ketoamide inhibitor (6r), Z-FL-COCHO (ZFL)] and cathepsin S-specific siRNA induced autophagy as indicated by an increase in the cleavage of the microtubule-associated protein light chain 3B (LC3B) and the formation of membrane-bound autophagic vacuoles (AVOs). In addition, co-treatment of a specific inhibitor of autophagy, 3-methyladenine (3MA), inhibited the 6r-induced autophagy in cancer cells. Further Western blot analysis revealed that targeting cathepsin S induced cancer cell autophagy through the activation of EGF receptor and its downstream MAPK-related signaling pathways. The induction of autophagy by targeting cathepsin S subsequently leads to the activation of apoptosis as indicated by both the up-regulation of caspase-9/3 activity, the down-regulation of Bcl-2, Bcl-XL and the altered mitochondrial membrane retention potential in cells. The application of the autophagy inhibitor, 3MA, was able to inhibit the process of apoptosis induced by the cathepsin S inhibitor 6r in cancer cells. In conclusion, the current study reveals that cathepsin S inhibitor is able to induce cancer cell autophagy through the EGF receptor signaling pathways, which may provide therapeutic benefit in cancer patients who are less sensitive to apoptosis-inducing agents.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2864. doi:10.1158/1538-7445.AM2011-2864

Design and synthesis of alpha-ketoamides as cathepsin S inhibitors with potential applications against tumor invasion and angiogenesis

A series of small molecules bearing an alpha-ketoamide warhead were synthesized and evaluated for their ability to inhibit cathepsin S, a key proteolytic enzyme upregulated in many cancers during tumor progression and metastasis. Most of the synthetic compounds were noncytotoxic, but several robustly inhibited cathepsin S (IC(50) < 10 nM) and potently suppressed cell migration, invasion, and capillary tube formation. These results highlight the potential of alpha-ketoamide therapy for preventing or delaying cancer spread.

Molecular characterization of invasive subpopulations from an esophageal squamous cell carcinoma cell line

BACKGROUND

Once diagnosed, esophageal cancer has a very low overall 5-year survival rate. This study investigates the mechanisms behind the invasiveness and severity of esophageal squamous cell carcinoma (ESCC).

MATERIALS AND METHODS

Transwell invasion chamber was used to subdivide one Taiwanese ESCC cell line, CE81T/VGH, into sublines (CE81T-0, CE81T-1, CE81T-2, CE81T-3, and CE81T-4) in four rounds of assays; the most invasive were identified, and various factors related to their invasiveness measured.

RESULTS

CE81T-1, CE81T-2, CE81T-3 and CE81T-4 sublines were significantly more invasive than the parental cells (CE81T/VGH) and CE81T-0 subline. CE81T-1 and CE81T-4, the sublines we chose to study further, had significantly greater colony-forming ability (3.5- to 2.7-fold) and wound migrating activity (1.95- to 2.6-fold) than the parental cells in vitro (p<0.01). They also displayed greater tumorigenesis in immunodeficient BALB/c Foxlnn mice than the parental cells. We found an inverse correlation between expression of tissue inhibitor of metalloproteinase-2 and invasive ability, and a significant positive correlation between expressions of matrix metalloproteinase-1, vimentin, and p-Src (pY416) in these cell lines and their invasiveness (all p<0.05).

CONCLUSION

The subline model may be used to study the molecular and genetic mechanisms underlying the invasion and metastasis of ESCC.

Epstein-Barr virus DNase (BGLF5) induces genomic instability in human epithelial cells

Epstein–Barr Virus (EBV) DNase (BGLF5) is an alkaline nuclease and has been suggested to be important in the viral life cycle. However, its effect on host cells remains unknown. Serological and histopathological studies implied that EBV DNase seems to be correlated with carcinogenesis. Therefore, we investigate the effect of EBV DNase on epithelial cells. Here, we report that expression of EBV DNase induces increased formation of micronucleus, an indicator of genomic instability, in human epithelial cells. We also demonstrate, using γH2AX formation and comet assay, that EBV DNase induces DNA damage. Furthermore, using host cell reactivation assay, we find that EBV DNase expression repressed damaged DNA repair in various epithelial cells. Western blot and quantitative PCR analyses reveal that expression of repair-related genes is reduced significantly in cells expressing EBV DNase. Host shut-off mutants eliminate shut-off expression of repair genes and repress damaged DNA repair, suggesting that shut-off function of BGLF5 contributes to repression of DNA repair. In addition, EBV DNase caused chromosomal aberrations and increased the microsatellite instability (MSI) and frequency of genetic mutation in human epithelial cells. Together, we propose that EBV DNase induces genomic instability in epithelial cells, which may be through induction of DNA damage and also repression of DNA repair, subsequently increases MSI and genetic mutations, and may contribute consequently to the carcinogenesis of human epithelial cells.

Identification of trypsin-inhibitory site and structure determination of human SPINK2 serine proteinase inhibitor

Human serine proteinase inhibitor Kazal-type 2 (SPINK2) functions as a trypsin/acrosin inhibitor and is synthesized mainly in the testis and seminal vesicle where its activity is engaged in fertility. The SPINK2 protein contains a typical Kazal domain composed by six cysteine residues forming three disulfide bridges. The expression of SPINK2 is closely related to cancer such as lymphomas, in that a high transcript level of SPINK2 in patients with primary cutaneous follicle center cell lymphomas have better prognosis with lower mortality. To clarify the role of SPINK2 in cancer, we performed quantitative real-time PCR and showed that the expression level of SPINK2 is significantly elevated in most leukemia cell lines except B-lymphoblast TK-6 cells. The molecular function and structural features of SPINK2 were also investigated by employing the recombinant active and mutant inactive SPINK2 proteins to determine its key P2-P2' (Pro(23)-Arg(24)-His(25)-Phe(26)) active site. The inhibition assay results demonstrated that Arg(24) at the P1 site is crucial for the specificity of SPINK2 on target enzyme. Although His(25) at the P1' and Phe(26) at the P2' residues are also involved in trypsin-SPINK2 interaction, Pro(23) at the P2 site may not be directly participated in interacting with trypsin. In addition, we determined the 3D solution structure of SPINK2 and used this structure to predict the SPINK2-proteinase complex structure and binding properties. These studies not only provide critical information about the structural properties and biophysical features of the SPINK2 proteinase inhibitor, but also suggest its important role in tumor progression and response to treatment.

Cooperation between NRF-2 and YY-1 transcription factors is essential for triggering the expression of the PREPL-C2ORF34 bidirectional gene pair

Background

Many mammalian genes are organized as bidirectional (head-to-head) gene pairs with the two genes separated only by less than 1 kb. The transcriptional regulation of these bidirectional gene pairs remains largely unclear, but a few studies have suggested that the two closely adjacent genes in divergent orientation can be co-regulated by a single transcription factor binding to a specific regulatory fragment. Here we report an evolutionarily conserved bidirectional gene pair, known as the PREPL-C2ORF34 gene pair, whose transcription relies on the synergic cooperation of two transcription factors binding to an intergenic bidirectional minimal promoter.

Results

While PREPL is present primarily in brain and heart, C2ORF34 is ubiquitously and abundantly expressed in almost all tissues. Genomic analyses revealed that these two non-homologous genes are adjacent in a head-to-head configuration on human chromosome 2p21 and separated by only 405 bp. Within this short intergenic region, a 243-bp GC-rich segment was demonstrated to function as a bidirectional minimal promoter to initiate the transcription of both flanking genes. Two key transcription factors, NRF-2 and YY-1, were further identified to coordinately participate in driving both gene expressions in an additive manner. The functional cooperation between these two transcription factors, along with their genomic binding sites and some cis-acting repressive elements, are essential for the transcriptional activation and tissue distribution of the PREPL-C2ORF34 bidirectional gene pair.

Conclusion

This study provides new insights into the complex transcriptional mechanism of a mammalian head-to-head gene pair which requires cooperative binding of multiple transcription factors to a bidirectional minimal promoter of the shared intergenic region.

Human kallikrein 8 protease confers a favorable clinical outcome in non-small cell lung cancer by suppressing tumor cell invasiveness

The human kallikrein 8 (KLK8) gene, a member of the human tissue kallikrein gene family, encodes a serine protease. The KLK8 protein (hK8) is known to be a favorable prognostic marker in ovarian cancer, but the biological basis of this is not understood. We found that overexpressing the KLK8 gene in highly invasive lung cancer cell lines suppresses their invasiveness. This role in invasiveness was further confirmed by the fact that inhibition of endogenous KLK8 expression with a specific short hairpin RNA reduced cancer cell invasiveness. In situ degradation and cell adhesion assays showed that proteins produced from KLK8 splice variants modify the extracellular microenvironment by cleaving fibronectin. DNA microarray experiments and staining of cells for actin filaments revealed that the degradation of fibronectin by hK8 suppresses integrin signaling and retards cancer cell motility by inhibiting actin polymerization. In addition, studies in a mouse model coupled with the detection of circulating tumor cells by quantitative PCR for the human Alu sequence showed that KLK8 suppresses tumor growth and invasion in vivo. Finally, studies of clinical specimens from patients with non-small cell lung cancer showed that the time to postoperative recurrence was longer for early-stage patients (stages I and II) with high KLK8 expression (mean, 49.9 months) than for patients with low KLK8 expression (mean, 22.9 months). Collectively, these findings show that KLK8 expression confers a favorable clinical outcome in non-small cell lung cancer by suppressing tumor cell invasiveness.

p53 Codon 72 and p21 Codon 31 Polymorphisms in Prostate Cancer

The tumor suppressor gene p53 and its downstream effector p21 are thought to play major roles in the development of human malignancy. Polymorphic variants of p53 at codon 72, and p21 at codon 31, have been found to be associated with cancer susceptibility, but few studies have investigated their effect on prostate cancer risk. In this case-control study, we investigated the association of p53 codon 72 and p21 codon 31 polymorphisms with prostate cancer risk in a Taiwanese population. In total, 200 patients with prostate cancer, 247 age-matched male controls, and 181 non–age-matched symptomatic benign prostatic hyperplasia (BPH; American Urological Association symptom score ≥ 8 and prostate volume &gt; 20 gm) recruited from two medical centers in southern Taiwan were genotyped. Overall, we found no significant association between p53 polymorphism and risk of prostate cancer. However, for p21 polymorphism, the frequencies of p21 Ser/Ser, Ser/Arg and Arg/Arg were 52 (26.0%), 85 (42.5%), 63 (31.5%) in case patients, 48 (26.5%), 82 (45.3%), 51 (28.2%) in BPH patients, and 76 (30.8%), 119 (48.2%), 52 (21.1%) in controls, respectively. Among the prostate cancer cases and controls, subjects with Arg/Arg genotype were found to have a 1.78-fold increased risk [95% confidence interval (CI), 1.06-3.01] of developing prostate cancer compared with those having the Ser/Ser genotype, after adjusting for other potential covariates. This significant association was slightly stronger [odds ratio (OR), 2.13; 95% CI, 1.16-3.92] in younger men (≤ 72 years; n = 99 and 126 for cases and controls, respectively) and correlated with localized disease stage (OR, 1.96; 95 % CI, 1.15-3.35) and moderately differentiated prostate cancer (OR, 2.04; 95% CI, 1.17-3.53). In addition, the Arg/Arg genotype was associated with BPH risk in those with large prostate volumes (&gt; 50 mL) compared with those having the Ser/Ser genotype [OR, 2.29; 95% CI, 1.07-4.98]. Our findings suggest that the p21 codon 31 polymorphism may be associated with the development of prostate enlargement and cancer.

p53 Codon 72 and p21 codon 31 polymorphisms in prostate cancer

The tumor suppressor gene p53 and its downstream effector p21 are thought to play major roles in the development of human malignancy. Polymorphic variants of p53 at codon 72, and p21 at codon 31, have been found to be associated with cancer susceptibility, but few studies have investigated their effect on prostate cancer risk. In this case-control study, we investigated the association of p53 codon 72 and p21 codon 31 polymorphisms with prostate cancer risk in a Taiwanese population. In total, 200 patients with prostate cancer, 247 age-matched male controls, and 181 non-age-matched symptomatic benign prostatic hyperplasia (BPH; American Urological Association symptom score > or = 8 and prostate volume > 20 gm) recruited from two medical centers in southern Taiwan were genotyped. Overall, we found no significant association between p53 polymorphism and risk of prostate cancer. However, for p21 polymorphism, the frequencies of p21 Ser/Ser, Ser/Arg and Arg/Arg were 52 (26.0%), 85 (42.5%), 63 (31.5%) in case patients, 48 (26.5%), 82 (45.3%), 51 (28.2%) in BPH patients, and 76 (30.8%), 119 (48.2%), 52 (21.1%) in controls, respectively. Among the prostate cancer cases and controls, subjects with Arg/Arg genotype were found to have a 1.78-fold increased risk [95% confidence interval (CI), 1.06-3.01] of developing prostate cancer compared with those having the Ser/Ser genotype, after adjusting for other potential covariates. This significant association was slightly stronger [odds ratio (OR), 2.13; 95% CI, 1.16-3.92] in younger men (< or = 72 years; n = 99 and 126 for cases and controls, respectively) and correlated with localized disease stage (OR, 1.96; 95 % CI, 1.15-3.35) and moderately differentiated prostate cancer (OR, 2.04; 95% CI, 1.17-3.53). In addition, the Arg/Arg genotype was associated with BPH risk in those with large prostate volumes (> 50 mL) compared with those having the Ser/Ser genotype [OR, 2.29; 95% CI, 1.07-4.98]. Our findings suggest that the p21 codon 31 polymorphism may be associated with the development of prostate enlargement and cancer.

Mouse model of membranous nephropathy induced by cationic bovine serum albumin: antigen dose-response relations and strain differences

BACKGROUND

Few well-characterized animal models have been developed to study the pathogenesis of membranous nephropathy (MN). We have developed a mouse model of MN induced by cationic bovine serum albumin (cBSA), and examined the role of genetic background on disease induction by assessing different mouse strains.

METHODS

cBSA in an optimum dose was given intravenously to 8-week-old female ICR, BALB/c and C57BL/6 mice for 4 weeks. The disease state was verified by renal histopathology as well as by serum and urine metabolic profiles. Serum concentrations of anti-cBSA immunoglobulins (Igs) and circulating immune complex (CIC) were assayed to study the mechanisms of initiation and progression. T-helper (Th) cell subsets in peripheral blood were examined using flow cytometry, and the Th1/Th2 subset distribution was determined by comparing the serum concentrations of IgG1 and IgG2a, using quantitative heterologous interpolation enzyme-linked immunosorbent assays.

RESULTS

Only ICR and BALB/c mice developed the typical clinical and pathological patterns of MN in response to an optimum dose of cBSA. Disease induction was dose related and strain specific. The serum concentrations of anti-cBSA were significantly higher in the strains that developed MN, but there were no differences in CIC concentrations. This suggests that in situ immune-complex glomerulonephritis may be involved in the development of MN. The Th2 type immune response may predominate in the ICR and BALB/c mice models, as the serum concentration of IgG1 was higher than that of IgG2a; moreover Th2 type strain specificity was necessary for the development of MN.

CONCLUSIONS

This improved mouse model of MN induced by cBSA more closely duplicates human MN than the other available models. Disease generation is antigen dose related and strain specific.

Association between vitamin D receptor polymorphisms and prostate cancer risk in a Taiwanese population

Recent molecular epidemiological studies have shown that the inherited polymorphisms of VDR gene may be linked to prostate cancer risk and its aggressive phenotypes. However, the findings remain inconclusive. In this study, we investigated the association of the BsmI, ApaI and TaqI polymorphisms of VDR gene with prostate cancer risk in a Taiwanese population. In total, 160 prostate cancer patients and 205 age-matched male controls were studied between December 2000 and February 2003. No significant associations were found between the ApaI and TaqI polymorphisms and the risk of prostate cancer. However, the control group was found to have a significantly higher frequency of the BsmI 'BB' and 'Bb' genotypes (15.6%) than prostate cancer patients (8.1%). After adjustment for age, patients with BsmI 'BB' or 'Bb' genotypes were associated with a twofold decreased risk (OR = 0.50; 95% CI = 0.25-0.98; P = 0.045) for developing prostate cancer than those with 'bb' genotypes. This effect was particularly significant among men below the median age of 72 years (P = 0.017). Moreover, stronger associations were found in the advanced stages (T3/T4/N1/M1) and poorly differentiated disease (Gleason score >/= 7) ('BB' and 'Bb' vs 'bb': OR = 0.25; 95% CI = 0.07-0.83; P = 0.024 and OR = 0.25; 95% CI = 0.07-0.85; P = 0.026, respectively). Our findings suggest that the VDR BsmI polymorphism may play a significant role in the development of prostate cancer.

Androgen receptor gene polymorphism and prostate cancer in Taiwan

BACKGROUND AND PURPOSE

The length of polymorphic CAG trinucleotide repeats in the polyglutamine region of the androgen receptor (AR) gene has been suggested to be inversely correlated with the transactivation function of the AR. An increase in androgen activity may be associated with prostate cancer, and ethnic variations in CAG repeat length may contribute to varying prostate cancer risks in different populations. This case-control study investigated the potential role of AR polymorphism in prostate cancer risk in Taiwanese.

METHODS

Sixty six pathologically-confirmed prostate cancer patients and 104 controls were studied. CAG repeat polymorphism was genotyped by a polymerase chain reaction (PCR)-based direct sequencing method. Logistic regression was used to determine the relative risk of AR gene CAG number on prostate cancer risk. The associations of AR-CAG polymorphism with disease stage, pathologic grade, and age at diagnosis were assessed. AR-CAG repeat number was first treated as a continuous variable, then was divided into short and long groups (n < 23 vs n > or = 23) for categorical analysis. The extreme groups of AR-CAG distribution were also analyzed for these associations (n < or = 20 vs n > or = 26 and n = 21-25 vs n > or = 26).

RESULTS

The mean number of CAG repeats in patients and controls was similar: 23.2 +/- 3.0 (range, 15 to 31) and 22.9 +/- 3.1 (range, 15 to 31), respectively. No association was found between AR-CAG repeat polymorphism and disease stage (p = 0.30), histological grade (p = 0.49), or age at diagnosis (p = 0.51). After adjusting for other covariates (age, body mass index, education level, smoking, and alcohol status), the number of AR-CAG repeats was not significantly associated with prostate cancer risk [odds ratio (OR) = 0.97, 95% confidence interval (95% CI) = 0.72 to 1.31; p = 0.84]. In categorical analysis, men with short CAG repeats (n < 23) did not have increased risk for prostate cancer (OR = 0.45, 95% CI = 0.29 to 1.05) compared to those with long CAG repeats (n > or = 23). Non-significant differences in prostate cancer risk were also found when comparing the extreme short group (n < or = 20) and the intermediate group (n = 21-25) to the extreme long group (n > or = 26) [n < or = 20 vs n > or = 26: OR = 1.00, 95% CI = 0.34 to 3.00; n = 21-25 vs n > or = 26: OR = 0.82, 95% CI = 0.37 to 1.81].

CONCLUSIONS

The results of this study do not support an important effect of AR-CAG repeat polymorphism on prostate cancer risk. A large-scale study is needed to clarify genetic components of prostate cancer risk in the Taiwanese population.