PDX1 associated therapy in translational medicine

Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extremely poor prognosis and a low median survival due to lack of the early and reliable detection and effective therapeutic options, despite improvements observed for many other cancers in last decade. Pancreatic and duodenal homeobox 1 (PDX1), which is a homeodomain-containing transcription factor and a key regulator for insulin gene expression, β cell maturation and proper β cell function maintenance in the pancreas. Our previous studies revealed that PDX1 promotes tumorigenesis and it is a promising therapeutic target for PDAC. For translational purposes, we developed three therapeutic platforms utilizing RNA interference (RNAi), gene therapy and small inhibitory drug targeting PDX1, and further validated them in PDAC preclinical models both in vitro and in vivo. These PDX1 targeted therapies significantly inhibited PDX1 expression in PDAC cells, ablated PDX1-expressing human PDAC xenograft tumor growth, and prolonged survival in the PDAC mouse models. The data from these preclinical studies proved the translational potentials of PDX1 targeted therapies in PDAC and suggest that the strategy of developing PDX1 targeted therapies would permit a rapid bench-to-bedside translation of other relevant gene therapies, which would eventually benefit the patients suffering from this deadly disease.

Gastric Metastasis of Hepatocellular Carcinoma With Gastrointestinal Bleeding After Liver Transplant: A Case Report

Gastrointestinal (GI) metastasis of hepatocellular carcinoma is very rare. This is the first report of post-transplantation gastric metastasis. A 43-year-old man with a history of hepatitis B-related hepatocellular carcinoma (HCC) in the right anterior segment of the liver received an orthotopic liver transplant. Three months after the transplantation, pulmonary metastasis was found by chest computed tomography, and he received 1 course of gamma knife treatment. He complained of melena with anemia 17 months post liver transplantation. Abdominal CT scan showed new occupying lesions in the liver and a mass in the stomach and around the spleen with embolus in the splenic vein. Endoscopy revealed a large irregular cauliflower-like mass in fundus with ulceration and bleeding on the surface. He received symptomatic treatment, but died of cancer-related bleeding 4 months later. GI bleeding may due to gastric metastasis after liver transplantation.

Associations between HLA-A\B\DRB1 polymorphisms and risks of vulvar lichen sclerosus or squamous cell hyperplasia of the vulva

In this study, we aimed to explore the associations between HLA-A\B\DRB1 polymorphisms and the risks of vulvar lichen sclerosus (VLS) or squamous cell hyperplasia of the vulva (SCHV) in Han Chinese women. We enrolled 76 Han Chinese women with VLS (Group A), 74 with SCHV (Group B), and 66 healthy women (control group) in this study. Polymerase chain reaction amplification with sequence specific primers (PCR-SSP) was used to determine HLA-A\B\DRB1 polymorphisms. Compared with the control group, HLA-A*11, -B*15, and -DRB1*12 were present at a higher frequency in groups A and B, while HLA-B*13 was present at a higher frequency in group A. Fewer women in group A carried HLA-A*31, -DRB1*01, and -DRB1*03 genotypes and fewer women in group B carried HLA-B*40 and -DRB1*03 genotypes. Significant differences were found between group B and the control group for HLA-A*11, -B*15, -B*40, and -DRB1*03, and between group A and the control group for HLA-B*15 and -DRB1*12. The HLA-A*11, HLA-B*13, HLA-B*15, and HLA-DRB1*12 genotypes were associated with a higher risk of VLS, while the HLA-A*31, HLA-DRB1*01, and HLA-DRB1*03 genotypes were associated with a lower risk of VLS. In addition, carrying HLA-A*11, HLA-B*15, HLA-B*35, and HLA-DRB1*12 genotypes, and carrying HLA-B*40 and HLA-DRB1*03 genotypes were found to be risk or protective factors for SCHV, respectively.

-173G/C polymorphism in the promoter of MIF is associated with hepatitis B virus infection in a Chinese Han population

In addition to the host immune response, genetic and environmental factors play crucial roles in the manifestation of hepatitis B virus (HBV) infection. The macrophage migration inhibitory factor (MIF) -173G/C polymorphism (rs755622), located in the promoter region of MIF, may play integral roles in diverse processes, including the immune response. Thus, the MIF -173G/C polymorphism may influence the immune response to HBV during natural infection. We investigated whether the MIF -173G/C polymorphism was associated with susceptibility to HBV infection in a Chinese Han population. A total of 596 HBV infection cases and 612 age-matched controls were recruited for the study. Genotyping of the MIF -173G/C polymorphism was performed using the allele-specific polymerase chain reaction method. The frequencies of the alleles and genotypes in patients and controls were compared using the χ(2) test. Carriers of the variant C allele in MIF -173 G/C were at significantly higher risk of HBV infection than carriers of the wild-type allele (P = 0.032, odds ratio = 0.799, 95% confidence interval = 0.651-0.981). However, there was no significant difference in the distribution of MIF -173G/C genotypes between case and control groups in either population (P = 0.096, degrees of freedom = 2). Our findings indicate that the G to C base change in MIF -173 G/C confers an increased risk of development of HBV infection by altering the expression of MIF in our Chinese Han population.

Liposomal insulin promoter-thymidine kinase gene therapy followed by ganciclovir effectively ablates human pancreatic cancer in mice

PDX1 is overexpressed in pancreatic cancer, and activates the insulin promoter (IP). Adenoviral IP-thymidine kinase and ganciclovir (TK/GCV) suppresses human pancreatic ductal carcinoma (PDAC) in mice, but repeated doses carry significant toxicity. We hypothesized that multiple cycles of liposomal IP-TK/GCV ablate human PDAC in SCID mice with minimal toxicity compared to adenoviral IP-TK/GCV. SCID mice with intraperitoneal human pancreatic cancer PANC-1 tumor implants were given a single cycle of 35 µg iv L-IP-TK, or four cycles of 1, 10, 20, 30, or 35 µg iv L-IP-TK (n = 20 per group), followed by intraperitoneal GCV. Insulin and glucose levels were monitored in mice treated with four cycles of 35 µg iv L-IP-TK. We found that four cycles of 10-35 µg L-IP-TK/GCV ablated more PANC-1 tumor volume compared to a single cycle with 35 µg. Mice that received four cycles of 10 µg L-IP-TK demonstrated the longest survival (P < 0.05), with a median survival of 126 days. In comparison, mice that received a single cycle of 35 µg L-IP-TK/GCV or GCV alone survived a median of 92 days and 68.7 days, respectively. There were no significant changes in glucose or insulin levels following treatment. In conclusion, multiple cycles of liposomal IP-TK/GCV ablate human PDAC in SCID mice with minimal toxicity, suggesting non-viral vectors are superior to adenoviral vectors for IP-gene therapy.

Antioxidant and hypoglycemic activities of exopolysaccharide by submerged culture of inocutus hispidus

This work was to investigate the hypoglycemic and antioxidant activities of the exopolysaccharides produced in a stirred-tank bioreactor by Inocutus hispidus. The exopolysaccharides showed significant antioxidant activities, up to 70.7±2.5% inhibition of hydroxyl radicals, 50% inhibition of 2,2-diphenyl-1-picrylhydrazyl radicals, and a Trolox equivalent antioxidant capacity of 3.3 mM. The exopolysaccharide also showed notable hypoglycemic effects in streptozotocin-induced diabetic mice, reducing the plasma glucose, total cholesterol and triacylglycerol concentrations by 18.2±1.5, 20.9±0.8 and 14.4±0.4, respectively. The results demonstrated the potential of this EPS for human health protection against oxidative damage and hyperglycemia.

Detection of methemoglobin in whole blood based on confocal micro-Raman spectroscopy and multivariate statistical techniques

Raman spectroscopy has been shown to have the potential for revealing oxygenated and spin ability of hemoglobin. In this study, confocal micro-Raman spectroscopy is developed to monitor the effect of sodium nitrite on oxyhemoglobin (HbO2 ) in whole blood. We observe that the band at 1,638 cm(-1) which is sensitive to the oxidation state decreases dramatically, while the 1,586 cm(-1) (low-spin state band) reduces both in methemoglobin (MetHb) and poisoning blood. Our results show that adding in sodium nitrite lead to the transition from HbO2 (Fe(2+) ) to MetHb (Fe(3+) ) in whole blood, and the iron atom converts from the low spin state to the high spin state with a delocalization from porphyrin plane. Moreover, multivariate statistical techniques, including principal components analysis (PCA) and linear discriminant analysis (LDA) are employed to develop effective diagnostic algorithms for classification of spectra between pure blood and poisoning blood. The diagnostic algorithms based on PCA-LDA yield a diagnostic sensitivity of 100% and specificity of 100% for separating poisoning blood from normal blood. Receiver operating characteristic (ROC) curve further confirms the effectiveness of the diagnostic algorithm based on PCA-LDA technique. The results from this study demonstrate that Raman spectroscopy combined with PCA-LDA algorithms has tremendous potential for the non-invasive detection of nitrite poisoning blood.

Down-regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5: a novel mechanism for inhibition of cellular proliferation and insulin secretion by somatostatin

Somatostatin (SST) is a regulatory peptide and acts as an endogenous inhibitory regulator of the secretory and proliferative responses of target cells. SST’s actions are mediated by a family of seven transmembrane domain G protein-coupled receptors that comprise five distinct subtypes (SSTR1-5). SSTR5 is one of the major SSTRs in the islets of Langerhans. Homeodomain-containing transcription factor pancreatic and duodenal homeobox-1 (PDX-1) is essential for pancreatic development, β cell differentiation, maintenance of normal β cell functions in adults and tumorigenesis. Recent studies show that SSTR5 acts as a negative regulator for PDX-1 expression and that SSTR5 mediates somatostatin’s inhibitory effect on cell proliferation and insulin expression/excretion through down-regulating PDX-1 expression. SSTR5 exerts its inhibitory effect on PDX-1 expression at both the transcriptional level by down-regulating PDX-1 mRNA and the post-translational level by enhancing PDX-1 ubiquitination. Identification of PDX-1 as a transcriptional target for SSTR5 may help in guiding the choice of therapeutic cancer treatments.

Development of 5Ns chromosome-specific SCAR markers for utilization in future wheat breeding programs

In previous studies, we developed a wheat-Psathyrostachys huashanica Keng disomic addition line 3-8-10-2, which exhibited high stripe rust resistance and could be used as a donor source for introducing novel disease resistance gene(s) into wheat in future breeding programs. It was identified using cytology, genomic in situ hybridization (GISH), EST-SSR, EST-STS and morphological analyses. However, these techniques are not suitable for breeding programs that require the rapid screening of large numbers of genotypes because they are highly technical and time-consuming. In this study, three Ns genome-specific SCAR markers were developed via random amplified polymorphic DNA (RAPD) markers. These SCAR markers were further validated using a complete set of wheat-P. huashanica disomic addition lines, which segregated the 5Ns disomic addition line individuals. Our results indicated that the SCAR markers associated with the 5Ns chromosome of P. huashanica and they provide a low cost, high efficiency, alternative tool for screening 5Ns chromosomes in a wheat background. These newly developed SCAR markers that species-specificity of the markers was proved by analysis of a wide range of cereal species, and specific for 5Ns chromosome, which should be useful in marker-assisted selection for wheat breeders who want to screen genotypes that may contain 5Ns chromatin.

Osteogenesis induced in goat bone marrow progenitor cells by recombinant adenovirus coexpressing bone morphogenetic protein 2 and basic fibroblast growth factor

Bone morphogenetic protein 2 (BMP2) and basic fibroblast growth factor (bFGF) have been shown to exhibit a synergistic effect to promote bone repair and healing. In this study, we constructed a novel adenovirus with high coexpression of BMP2 and bFGF and evaluated its effect on osteogenic differentiation of goat bone marrow progenitor cells (BMPCs). Recombinant adenovirus Ad-BMP2-bFGF was constructed by using the T2A sequence. BMPCs were isolated from goats by density gradient centrifugation and adherent cell culture, and were then infected with Ad-BMP2-bFGF or Ad-BMP2. Expression of BMP2 and bFGF was detected by ELISA, and alkaline phosphatase (ALP) activity was detected by an ALP assay kit. In addition, von Kossa staining and immunocytochemical staining of collagen II were performed on BMPCs 21 days after infection. There was a high coexpression of BMP2 and bFGF in BMPCs infected with Ad-BMP2-bFGF. Twenty-one days after infection, ALP activity was significantly higher in BMPCs infected with Ad-BMP2-bFGF than in those infected with Ad-BMP2. Larger and more mineralized calcium nodules, as well as stronger collagen II staining, were observed in BMPCs infected with Ad-BMP2-bFGF than in those infected with Ad-BMP2. In summary, we developed a novel adenovirus vector Ad-BMP2-bFGF for simultaneous high coexpression of BMP2 and bFGF, which could induce BMPCs to differentiate efficiently into osteoblasts.

Notch1 activation up-regulates pancreatic and duodenal homeobox-1

Transcription factor pancreatic and duodenal homeobox-1 (PDX-1) plays an essential role in pancreatic development, β-cell differentiation, maintenance of normal β-cell function and tumorigenesis. PDX-1 expression is tightly controlled through a variety of mechanisms under different cellular contexts. We report here that overexpression of Notch1 intracellular domain (NICD), an activated form of Notch1, enhanced PDX-1 expression in both PDX-1 stable HEK293 cells and mouse insulinoma β-TC-6 cells, while NICD shRNA inhibited the enhancing effect. NICD-enhanced PDX-1 expression was accompanied by increased insulin expression/secretion and cell proliferation in β-TC-6 cells, which was reversed by NICD shRNA. Cre activation-induced specific expression of NICD in islet β cells of transgenic β^NICD+/+ mice induced increased expression of PDX-1, insulin and proliferating cell nuclear antigen (PCNA) and decreased expression of p27 with accompanied fasting hyperinsulinemia and hypoglycemia and altered responses to intraperitoneal glucose tolerance test. Systemically delivered NICD shRNA suppressed islet expression of PDX-1 and reversed the hypoglycemia and hyperinsulinemia. Moreover, expression levels of NICD were correlated with those of PDX-1 in human pancreatic neuroendocrine tumor. Thus, Notch1 acts as a positive regulator for PDX-1 expression, cooperates with PDX-1 in the development of insulin overexpression and islet cell neoplasia and represents a potential therapeutic target for islet neoplasia.

In vivo detection of Hirschsprung's disease by optical coherence tomography in rats

Hirschsprung's disease (HSCR) is a developmental intestinal obstruction, which is often diagnosed with a repeated biopsy. Optical coherence tomography (OCT) is a noninvasive, real-time imaging modality. This study aims to investigate the feasibility of diagnosis of HSCR, the targeted biopsies of suspicious tissues and the location of operative treatment using OCT. An HSCR Sprague-Dawley (SD) rat model (benzalkonium chloride-treated (BAC-treated)) was used. Colon tissues with BAC-treated and without BAC-treated were imaged using OCT. To establish OCT criteria for identification of HSCR, OCT images were compared with corresponding histology images and muscle layer thickness was measured. Furthermore, attenuation coefficients of OCT signals were calculated to illustrate the differences between tissues with BAC-treated and without BAC-treated. Our results show that OCT images of colon tissues with HSCR are well correlated with histology images. In comparison with a muscle layer without HSCR, the thickness of muscle layer with HSCR is increased significantly. The muscle layer in colon tissues with HSCR for 6 weeks had a higher attenuation coefficient than those without HSCR. However, the attenuation coefficient of those with HSCR for 3 weeks had no obvious change. In conclusion, the study demonstrates for the first time that OCT has the potential for diagnosis, biopsy and location of HSCR in vivo.

Second harmonic generation in 3-d uniform arrangement of type I collagen on nonlinear optics microscopy

Second harmonic microscopic imaging and spectroscopy technology has become a powerful tool for biomedical studies, especially in fibrosis-related diseases research. And type I collagen is the major risk factors for fibrotic diseases. In this study, model for three-dimensional (3-D) uniform arrangement type I collagen is set up for researching the second harmonic generation (SHG) on nonlinear optics microscopy. Based on this model, we discuss the influence of different length and size collagen in 3-D arrangement type I collagen. Results can guide us to neatly judge the size, length, and molecules density effect on SHG. For practical application, this theoretical approach can lead us to analyze different severity of collagen diseases.

New half-lives of r-process Zn and Ga isotopes measured with electromagnetic separation

The β decays of neutron-rich nuclei near the doubly magic (78)Ni were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of (82)Zn (228±10  ms), (83)Zn (117±20  ms), and (85)Ga (93±7  ms) were determined for the first time. These half-lives were found to be very different from the predictions of the global model used in astrophysical simulations. A new calculation was developed using the density functional model, which properly reproduced the new experimental values. The robustness of the new model in the (78)Ni region allowed us to extrapolate data for more neutron-rich isotopes. The revised analysis of the rapid neutron capture process in low entropy environments with our new set of measured and calculated half-lives shows a significant redistribution of predicted isobaric abundances strengthening the yield of A>140 nuclei.

Association analysis of dopaminergic gene variants (Comt, Drd4 And Dat1) with Alzheimer s disease

Defects in dopaminergic transmission play important roles in the disturbance of synaptic plasticity and even in advanced cognitive behavior. However, the relationship between genes involved in the regulation of dopamine levels and predisposition for Alzheimer s disease (AD) remains unclear. The potential association of dopamine-modulating gene polymorphisms with AD was evaluated. We performed a case-control study with 120 patients and 86 healthy controls. Two catechol-O-methyltransferase (COMT) single-nucleotide polymorphisms (SNPs) (rs2020917 and rs4646312), two dopamine D4 receptor (DRD4) SNPs (rs3758653 and rs916455), and four dopamine transporter (DAT1) SNPs (rs2937639, rs6347, rs12516948 and rs11133762) were investigated. The T allele at the DRD4 SNP (rs3758653) was found to be significantly associated with AD. Our results also showed that haplotype frequencies, observed from the analyzed SNPs, were distributed significantly differently in AD patients vs control subjects. Moreover, a strong association was observed between the A allele at rs6347 of DAT1 and moderate stage of dementia. These observations suggest that genetic variations in the dopamine-modulating genes, COMT, DRD4 and DAT1, may contribute to AD pathogenesis in the Taiwanese population.

Negative regulation of pancreatic and duodenal homeobox-1 by somatostatin receptor subtype 5

Somatostatin receptor subtype 5 (SSTR5) mediates the inhibitory effect of somatostatin and its analogs on insulin expression/secretion and islet cell proliferation. We provide biochemical and genetic evidence that SSTR5 exerted its physiological actions via down-regulating pancreatic and duodenal homeobox-1 (PDX-1), a β-cell-specific homeodomain-containing transcription factor. Cotransfection of SSTR5 with PDX-1 resulted in dose-dependent inhibition of PDX-1 expression in human embryonic kidney 293 cells. SSTR5 agonist RPL-1980 inhibited PDX-1 expression and abolished glucagon-like peptide 1-stimulated PDX-1 expression in mouse insulinoma β-TC-6 cells. SSTR5 knockdown by short hairpin RNA led to increased PDX-1 expression that was accompanied by enhanced insulin secretion stimulated by high glucose in β-TC6 cells and alternated expressions of cell cycle proteins that favor cell proliferation in mouse insulinoma MIN6 cells. Quantitative RT-PCR analysis showed that cotransfected SSTR5 inhibited PDX-1 mRNA expression, whereas knockdown of SSTR5 increased PDX-1 mRNA expression. In addition, we found that cotransfected wild-type SSTR5 increased PDX-1 ubiquitination in human embryonic kidney 293 cells, whereas SSTR5 P335L, a hypofunctional single nucleotide polymorphism of SSTR5, inhibited PDX-1 ubiquitination. SSTR5 knockout resulted in increased expression of PDX-1, insulin, and proliferating cell nuclear antigen in the islets of sstr(-/-) mice. Immunohistochemistry analysis showed that SSTR5 P335L was associated with elevated expression of PDX-1 in human pancreatic neuroendocrine tumor. Taken together, our studies demonstrated that SSTR5 is a negative regulator for PDX-1 expression and that SSTR5 may mediate the inhibitory effects of somatostatin and its analogs on insulin expression/secretion and cell proliferation via down-regulating PDX-1 at both transcriptional and posttranslational levels.

Micro-Raman spectroscopy study of the effect of Mid-Ultraviolet radiation on erythrocyte membrane

Mid-Ultraviolet (UVB) has a significant influence on human health. In this study, human erythrocytes were exposed to UVB to investigate the effects of UVB radiation on erythrocytes membrane. And Micro-Raman spectroscopy was employed to detect the damage. Principal component analysis (PCA) was used to classify the control erythrocytes and the irradiated erythrocytes. Results showed that the erythrocytes membrane was damaged by Mid-Ultraviolet (UVB) radiation. The intensity of the Raman peaks at 1126 cm(-1) and 1082 cm(-1) were used to calculate the Longitudinal Order-Parameters in Chains (S(trans)) which can present the liquidity and ionic permeability of erythrocyte membrane. After UVB radiation for 30 min, both the liquidity and ionic permeability decreased. At the same time, the intensity of the peaks at 1302 cm(-1) (α-helix), 1254 cm(-1) (random coil), 1452 cm(-1) and 1430 cm(-1) (CH(2)/CH(3) stretch) have also changed which indicated the membrane protein also been damaged by UVB. In the whole process of radiation, the more UVB radiation dose the more damage on the erythrocyte membrane.

Personalized cancer approach: using RNA interference technology

Normal cellular survival is dependent on the cooperative expression of genes' signaling through a broad array of DNA patterns. Cancer, however, has an Achilles' heel. Its altered cellular survival is dependent on a limited subset of signals through mutated DNA, possibly as few as three. Identification and control of these signals through the use of RNA interference (RNAi) technology may provide a unique clinical opportunity for the management of cancer that employs genomic-proteomic profiling to provide a molecular characterization of the cancer, leading to targeted therapy customized to an individual cancer signal. Such an approach has been described as "personalized therapy." The present review identifies unique developing technology that employs RNAi as a method to target, and therefore block, signaling from mutated DNA and describes a clinical pathway toward its development in cancer therapy.

SSTR5 P335L monoclonal antibody differentiates pancreatic neuroendocrine neuroplasms with different SSTR5 genotypes

BACKGROUND

Somatostatin receptor type 5 (SSTR5) P335L is a hypofunctional, single nucleotide polymorphism of SSTR5 with implications in the diagnostics and therapy of pancreatic neuroendocrine neoplasms. The purpose of this study is to determine whether a SSTR5 P335L-specific monoclonal antibody could sufficiently differentiate pancreatic neuroendocrine neoplasms (PNENs) with different SSTR5 genotypes.

METHODS

Cellular proliferation rate, SSTR5 mRNA level, and SSTR5 protein level were measured by performing MTS assay, a quantitative reverse transcription polymerase chain reaction study, Western blot analysis, and immunohistochemistry, respectively. SSTR5 genotype was determined with the TaqMan SNP Genotyping assay (Applied Biosystems, Foster City, CA).

RESULTS

We found that the SSTR5 analogue RPL-1980 inhibited cellular proliferation of CAPAN-1 cells more than that of PANC-1 cells. Only PANC-1 (TT) cells, but not CAPAN-1 (CC) cells expressed SSTR5 P335L. In 29 white patients with PNENs, 38% had a TT genotype for SSTR5 P335L, 24% had a CC genotype for WT SSTR5, and 38% hada CT genotype for both SSTR5 P335L and WT SSTR5. Immunohistochemistry using SSTR5 P335L monoclonal antibody detected immunostaining signals only from the neuroendocrine specimens with TT and CT genotypes, but not those with CC genotypes.

CONCLUSION

A SSTR5 P335L monoclonal antibody that specifically recognizes SSTR5 P335L but not WT SSTR5 could differentiate PNENs with different SSTR5 genotypes, thereby providing a potential tool for the clinical diagnosis of PNEN.

Somatostatin receptor 1 and 5 double knockout mice mimic neurochemical changes of Huntington's disease transgenic mice

BACKGROUND

Selective degeneration of medium spiny neurons and preservation of medium sized aspiny interneurons in striatum has been implicated in excitotoxicity and pathophysiology of Huntington's disease (HD). However, the molecular mechanism for the selective sparing of medium sized aspiny neurons and vulnerability of projection neurons is still elusive. The pathological characteristic of HD is an extensive reduction of the striatal mass, affecting caudate putamen. Somatostatin (SST) positive neurons are selectively spared in HD and Quinolinic acid/N-methyl-D-aspartic acid induced excitotoxicity, mimic the model of HD. SST plays neuroprotective role in excitotoxicity and the biological effects of SST are mediated by five somatostatin receptor subtypes (SSTR1-5).

METHODS AND FINDINGS

To delineate subtype selective biological responses we have here investigated changes in SSTR1 and 5 double knockout mice brain and compared with HD transgenic mouse model (R6/2). Our study revealed significant loss of dopamine and cAMP regulated phosphoprotein of 32 kDa (DARPP-32) and comparable changes in SST, N-methyl-D-aspartic acid receptors subtypes, calbindin and brain nitric oxide synthase expression as well as in key signaling proteins including calpain, phospho-extracellular-signal-regulated kinases1/2, synapsin-IIa, protein kinase C-α and calcineurin in SSTR1/5(-/-) and R6/2 mice. Conversely, the expression of somatostatin receptor subtypes, enkephalin and phosphatidylinositol 3-kinases were strain specific. SSTR1/5 appears to be important in regulating NMDARs, DARPP-32 and signaling molecules in similar fashion as seen in HD transgenic mice.

CONCLUSIONS

This is the first comprehensive description of disease related changes upon ablation of G- protein coupled receptor gene. Our results indicate that SST and SSTRs might play an important role in regulation of neurodegeneration and targeting this pathway can provide a novel insight in understanding the pathophysiology of Huntington's disease.

The hypofunctional effect of P335L single nucleotide polymorphism on SSTR5 function

BACKGROUND

Somatostatin receptor subtype 5 (SSTR5) mediates the inhibitory effect of somatostatin on insulin expression/secretion and cell proliferation. A number of single nucleotide polymorphisms (SNPs) of SSTR5 have been identified, including P335L, a nonsynonymous SNP located in the protein C-terminal region and encrypted by the codon CCG (proline) or the codon CTG (leucine). In the present study we sought to determine the distribution of the SSTR5 P335L SNP in a cohort of pancreatic cancer patients and whether the P335L SNP affected cellular function of SSTR5 in human pancreatic cancer.

METHODS

The P335L germline genotype of 246 patients with pancreatic cancer (213 Caucasians, 16 Hispanics, and 17 African Americans) and 17 human pancreatic cell lines was determined with the TaqMan SNP Genotyping assay. Human SSTR5 leucine variant (L335) was generated by performing site-directed mutagenesis using SSTR5 proline variant (P335) as a template. Transient transfections were performed in HEK293, Mia PaCa-2, and β-TC-6 cells using Lipofectamine 2000. The expression of SSTR5 L335 was determined with a mouse monoclonal anti-SSTR5 L335 antibody generated in our laboratory. The cell proliferation rate was measured by performing MTS assays. Insulin concentration was measured by performing ELISA assays.

RESULTS

Genotyping of the patients' blood indicated that the frequency of the T allele (CT and TT genotypes) in codon 335 of SSTR5 in Caucasians, Hispanics, and African Americans was 52, 69, and 35%, respectively, which was race-dependent. Statistical analysis indicated that association between the frequency of the T allele and the existence of pancreatic cancer in each race missed significance perhaps due to limited sample size. In 17 tested human pancreatic cancer cell lines, 5 (Capan-2, HPAF-II, Panc03.27, Panc-1, and -3) were homozygous (TT genotype) and 9, including Mia PaCa-2, were heterozygous (CT genotype). Overexpression of SSTR5 L335 in Mia PaCa-2 cells enhanced cell proliferation compared to overexpression of SSTR5 P335. Overexpression of SSTR5 P335 enhanced the inhibitory effect of SSTR5 agonist RPL-1980 on cell proliferation of Mia PaCa-2 cells and glucose-stimulated insulin secretion from mouse insulinoma cells, while overexpression of SSTR5 L335 blocked the inhibitory effect of RPL-1980. Overexpression of SSTR5 L335 enhanced PDX-1 expression in Mia PaCa-2 cells. A specific monoclonal antibody was generated to detect SSTR5 P335L.

CONCLUSION

SSTR5 P335L SNP widely exists in the human population, in patients with pancreatic cancer, and is race-dependent. The SNP is also present in selected human pancreatic cancer cell lines. In contrast to SSTR5 P335, overexpression of the SSTR5 L335 variant resulted in cellular proliferation and PDX-1 overexpression in human pancreatic cancer cells. Its overexpression blocked the inhibitory effect of an SSTR5-specific analog on human pancreatic cancer cell proliferation and on glucose-stimulated insulin secretion from mouse insulinoma cells. These data suggest that SSTR5 P335L is a hypofunctional protein with a potentially harmful effect on function, as well as potential latent effect, and therefore it could affect the clinical response to somatostatin analog therapy for patients with pancreatic cancer.

Serum response factor expression is enriched in pancreatic β cells and regulates insulin gene expression

Serum response factor (SRF) is an essential regulator of myogenic and neurogenic genes and the ubiquitously expressed immediate-early genes. The purpose of this study is to determine SRF expression pattern in murine pancreas and examine the role of SRF in pancreatic gene expression. Immunohistochemical analysis of wild-type pancreas and LacZ staining of pancreas from SRF LacZ knock-in animals showed that SRF expression is restricted to β cells. SRF bound to the rat insulin promoter II (RIP II) serum response element, an element conserved in both rat I and murine I and II insulin promoters. SRF activated RIP II, and SRF binding to RIP II and the exon 5-encoded 64-aa subdomain of SRF was required for this activation. Transient or stable knockdown of SRF leads to down-regulation of insulin gene expression, suggesting that SRF is required for insulin gene expression. Further, SRF physically interacted with the pancreas and duodenum homeobox-1 (Pdx-1) and synergistically activated RIP II. Elevated glucose concentration down-regulated SRF binding to RIP II SRE, and this down-regulation was associated with decreased RIP II activity and increased SRF phosphorylation on serine 103. Together, our results demonstrate that SRF is a glucose concentration-sensitive regulator of insulin gene expression.

Fine-mapping of quantitative trait loci for body weight and bone traits and positional cloning of the RB1 gene in chicken

Previously, a quantitative trait locus (QTL) that affects body weight (BW) at 4-12 weeks of age and carcass weight at 12 weeks of age had been mapped on chicken chromosome 1. After including more markers and individuals, the confidence interval was narrowed down to approximately 5.5 Mbps and located this QTL near a microsatellite marker (ADL328). This QTL is the same as the QTL for 12 bone traits, including metatarsus length and metatarsus circumference at 4, 6, 8, 10 and 12 weeks of age and keel length and metatarsus claw weight at 12 weeks of age, that was identified using the same population. In the current study, 1010 individuals from the Northeast Agricultural University F(2) resource population were used and 14 single-nucleotide polymorphism (SNPs) around ADL328 were developed to construct haplotypes, and an association analysis was performed to fine-map the QTL. The haplotypes were constructed on the basis of a sliding 'window', with three SNP markers included in each 'window'. The association analysis results indicated that the haplotypes in 'windows' 6-12 were significantly associated with BW and bone traits and suggested that the QTL for BW and bone traits was located between SNP8 and SNP14 or was in linkage disequilibrium with this region. The interval from SNP8 to SNP14 was approximately 400 kbps. This region contained five RefSeq genes (RB1, P2RY5, FNDC3A, MLNR and CAB39L) on the University of California Santa Cruz website. The RB1 gene was selected as a candidate gene and five SNPs were identified in the gene. The association results indicated that the RB1 gene was a major gene for BW and bone traits. The SNPs g.39692 G>A and g.77260 A>G in RB1 gene might be two quantitative trait nucleotides for BW and bone traits.

Multiple treatment cycles of liposome-encapsulated adenoviral RIP-TK gene therapy effectively ablate human pancreatic cancer cells in SCID mice

BACKGROUND

Adenoviral gene therapy has been applied widely for cancer therapy; however, transient gene expression as result of humoral immunoneutralization response to adenovirus limits its effect. The purpose of this study is to determine whether DOTAP:cholesterol liposome could shield adenovirus from neutralizing antibody and permit the use of multiple cycles of intravenous liposome encapsulated serotype 5 adenoviral rat insulin promoter directed thymidine kinase (L-A-5-RIP-TK) with ganciclovir (GCV) to enhance its effect.

METHODS

The effect of multiple cycles of systemic L-A-5-RIP-TK/GCV therapy was evaluated in grouped PANC-1 SCID mice treated with different numbers of cycles. Humoral immune response to A-5-RIP-TK or L-A-5-RIP-TK was assessed using C57/B6J mice challenged with adenovirus or liposome adenovirus complex.

RESULTS

The minimal residual tumor burden (3.2 ± 0.6 mm(3)) and greatest survival time (153.0 ± 6 days) were obtained in the mice receiving 4 and 3 cycles of therapy, respectively. Toxicity to islet cells associated with RIP-TK/GCV therapy was observed after 4 cycles. DOTAP:chol-encapsulated adenovectors were able to protect adenovectors from the neutralization of high titer of anti-adenoviral antibodies induced by itself.

CONCLUSION

Multiple treatment cycles of L-A-5-RIP-TK/GCV ablate human PANC-1 cells effectively in SCID mice; however, the mice become diabetic and have substantial mortality after the 4th cycle. Liposome-encapsulated adenovirus is functionally resistant to the neutralizing effects of anti-adenoviral antibodies, suggesting feasibility of multiple cycles of therapy. Liposome encapsulation of the adenovirus may be a promising strategy for repeated delivery of systemic adenoviral gene therapy.

Defining the cancer master switch

BACKGROUND

Recent research has focused on signaling cascades and their interactions yielding considerable insight into which genetic pathways are targeted and how they tend to be altered in tumors. Therapeutic interventions now can be designed based on the knowledge of pathways vital to tumor growth and survival. These critical targets for intervention, master switches for cancer, are termed so because the tumor attempts to "flip the switch" in a way that promotes its survival, whereas molecular therapy aims to "switch off" signals important for tumor-related processes.

METHODS

Literature review.

CONCLUSIONS

Defining useful targets for therapy depends on identifying pathways that are crucial for tumor growth, survival, and metastasis. Because not all signaling cascades are created equal, selecting master switches or targets for intervention needs to be done in a systematic fashion. This discussion proposes a set of criteria to define what it means to be a cancer master switch and provides examples to illustrate their application.