Study of genotypic variations and protein expression of the xCT subunit of cystine/glutamate transporter in pancreatic cancer

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Background: The plasma membrane xCT cystine-specific subunit of the cystine/glutamate transporter contributes to chemotherapy resistance in pancreatic cancer by regulating intracellular glutathione levels and protecting cancer cells against oxidative stress. We previously noted that the rs7674870 single nucleotide polymorphism (SNP) of xCT correlated with overall survival in pancreatic cancer and may be predictive of platinum resistance. There are no data regarding xCT protein expression in pancreatic cancer or the functional significance of this SNP.

Methods: Paraffin-embedded core and surgical biopsy tumor specimens from 49 patients with metastatic pancreatic adenocarcinoma were analyzed by immunohistochemistry (IHC) using an xCT specific antibody (Novus Biologicals). xCT protein IHC expression scores (product of intensity and percentage of staining cells) were analyzed in relation to overall survival and genotype of the patients using the one factor ANOVA test, Kaplan-Meier plot, log-rank test, and Cox regression analysis. Overall survival was measured from the date of diagnosis to the date of death or last follow-up.

Results: Positive xCT expression was detected in 38 (78%) of the 49 samples, and 9 (18%) patients had high levels of expression. High xCT expression was associated with lower overall survival as compared with low expression (5.1 months versus 8.8 months; p = 0.119). In a multivariate Cox regression model with adjustment for prognostic parameters of age, sex, performance status and CA19-9 level, high xCT expression was associated with a 2.1-fold increased risk of death (p = 0.096). Performance status also correlated with overall survival (p = 0.027). Preliminary analysis on the genotype-phenotype association (n = 12) indicated that xCT expression was higher with the TT genotype than the TC/CC genotype (p = 0.115), which is consistent with the previous observation that the TT genotype was associated with reduced survival.

Conclusions: These data provide supporting evidence for a possible role of cystine/glutamate transporter xCT subunit in pancreatic cancer progression and survival. Further pharmacogenomic and clinicopathologic studies are ongoing.

No significant financial relationships to disclose.

Differential expression of small ubiquitin-like modifier family of proteins in patients with colorectal adenocarcinoma

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Background: The cytotoxic effects of radiation and chemotherapy are mediated in part by DNA damage. The small ubiquitin-like modifier (SUMO) family of proteins regulates DNA repair pathways by activating factors involved in homologous recombination (HR) or non- homologous end joining (NHEJ). Our objective was to determine the potential role of SUMO proteins in patients with colorectal cancer.

Methods: We first assessed two established colorectal cancer cell lines (HCT116 and HT29) and two normal colonic mucosa cell populations utilizing ultra high-throughput expression analysis (Solexa) to examine differential expression of genes involved in SUMOylation (SAE1, SAE2, PIAS-1, and DNAPKcs). To verify the clinical relevance of SUMOylation in colorectal cancer, we obtained archived specimens from patients with colorectal cancer (n=51) and examined the expression of these proteins in both benign and malignant tissue by immunohistochemistry (IHC).

Results: Ultra high-throughput expression analysis of cancer and normal cells revealed a 10 to 15-fold upregulation of SAE2 (heterodimer of the E1 activation enzyme in SUMOylation), a 10 to 11-fold upregulation of DNAPKcs (catalytic subunit in NHEJ repair pathway), and a 6-fold upregulation of SAE1 in cancer cells. In contrast, PIAS-1 showed similar expression levels between cancer and normal colonic cells. By IHC, SAE1 and SAE2 were highly expressed in 65% and 53% of tumor specimens, respectively; but only in 7% and 0% of normal tissues, respectively. DNAPKcs was also highly expressed in tumor tissues (63%) with corresponding low expression (0%) in normal tissues. Corroborating the cell line results, PIAS-1 was infrequently expressed in both tumor (10%) and normal tissues (0%).

Conclusions: We are the first to demonstrate the differential expression of SUMO proteins in colorectal cancer cell lines and in clinical specimens. SUMO proteins have a role in DNA repair and their expression in colorectal cancer may modify tumor response to chemoradiotherapy.

No significant financial relationships to disclose.

High dose human insulin and insulin glargine promote T24 bladder cancer cell proliferation via PI3K-independent activation of Akt

BACKGROUND

This study was to investigate the effects of human insulin and insulin glargine on proliferation of T24 human bladder cancer cells and the implication of the PI3K/Akt and MEK/ERK1/2 pathways.

METHODS

After exposure to insulin or glargine at the indicated concentrations for certain time courses, in the absence or presence of inhibitor for MEK (PD98059) or PI3K (LY294002), T24 cell proliferation was evaluated by CCK-8 assay. Phosphorylation of Akt and ERK1/2 was analyzed by Western blot.

RESULTS

Insulin and glargine similarly induced phosphorylation of Akt and slight increases in T24 cell proliferation at 10-100IU/L. LY294002 remarkably reduced T24 cell proliferation in all groups. However, in the presence of LY294002, cell growth was still promoted by insulin and glargine relative to LY294002-treated group. Accordingly, LY294002 profoundly reduced protein levels of pAkt, while insulin and glargine increased pAkt in T24 cells pretreated with LY294002 as compared with cells treated with LY294002 alone. PD98059 reduced pERK while enhanced T24 cell proliferation. Insulin and glargine increased pERK at 15, 30, 60 min, not at 24h.

CONCLUSIONS

High dose human insulin and insulin glargine similarly promoted T24 bladder cancer cell proliferation via PI3K-independent activation of Akt.

First Report of Bacterial Wilt Caused by Ralstonia solanacearum on Mesona chinensis in China

Jellywort (Mesona chinensis Benth) is an herbaceous plant in the Lamiaceae (mint) family. The plant is referred to as 'Xiancao' (weed from angels) in Chinese and primarily used to make grass jelly, a popular refreshing drink. Currently, Xiancao cultivation is a fast-growing industry with a high profit margin in southern China. An estimated 7,000 ha is grown with a value of more than $50 million USD. In June, 2009, a wilting disease of Xiancao was observed in Guangdong and the neighboring Guangxi and Fujian provinces with incidence up to 50% in the severest case. Affected plants initially show withering symptoms on apical leaves during the daytime with recovery at night. As the disease develops, withering leaves spread downward, eventually encompassing the whole plant. Leaves lose vigor but remain green. After 3 to 4 days, wilting becomes irreversible. Roots and basal stem tissues blacken and rot, leading to plant death. Longitudinal sectioning of the basal stem shows browning of vascular tissues with whitish ooze visible when compressed. To investigate the disease etiology, 12 Xiancao plants from three cultivars showing typical wilting symptoms were collected from a production field in Zengcheng City of Guangdong Province in June 2010. A total of 27 bacterial isolates showing large, elevated, and fluidal colonies with a pale red center were isolated from vascular tissue on tripheny tetrazolium chloride medium (3) after incubation at 30° for 2 days. Fifteen 45-day-old Xiancao plants (cv. Zhengcheng 1) were inoculated by injection of 20 μl of bacterial suspension (1 × 10⁸ CFU/ml) into the middle stem. Sterile water was used as a negative control. After 4 to 6 days of incubation in a greenhouse (28 to 30°), all (15 of 15) inoculated plants developed wilting symptoms as described above. The same bacterium was reisolated from inoculated plants. The five negative control plants did not show any wilting symptoms. With the same artificial inoculation procedure, this bacterium also caused similar wilting disease in tobacco, potato, tomato, pepper, and eggplant. An inoculation test with a tomato strain of Ralstonia solanacearum resulted in similar symptoms. On the basis of symptomatology and bacterial culture characteristics, R. solanacearum (formerly Pseudomonas solanacearum) was suspected as the causal agent. For confirmation, the universal bacterial 16S rDNA primer set E8F/E1115R (1) was used to amplify DNA from pure culture. A 1,027-bp DNA sequence was obtained and deposited in GenBank with Accession No. HQ159392. BLAST search against the current version of GenBank database showed 100% similarity with the 16S rDNA sequences of 26 R. solanacearum strains. Furthermore, primer set 759/760 (4) amplified a specific 280-bp fragment. Along with the result from multiplex PCR (2), the bacterium was identified as R. solanacearum Phylotype I. To our knowledge, this is the first report of a disease caused by R. solanacearum on M. chinensis. References: (1) G. Baker et al. J. Microbiol. Methods 55:541, 2003. (2) M. Fegan and P. Prior. Page 449 in Bacterial Wilt Disease and the Ralstonia solanacearum Species Complex. C. Allen et al., eds. The American Phytopathological Society. St. Paul, MN, 2005. (3) A. Kelman, Phytopathology 44:693, 1954. (4) N. Opina et al. Asia Pac. J. Mol. Biol. Biotechnol. 5:19, 1997.

Marek's disease resistant/susceptible MHC haplotypes in Xiayan chickens identified on the basis of BLB2 PCR-RFLP and BLB2/BF2 sequence analyses

1. The aim was to analyse the variability of the BLB2/BF2 genes of Xiayan chickens to identify homozygous birds with resistance or susceptibility to Marek's disease (MD). 2. The experiment used two lines: birds from a common line were divided into Group A (unvaccinated) and Group B (vaccinated with herpesvirus of turkeys (HVT)); and birds from an MD-resistant line were divided into Group C (unvaccinated) and Group D (vaccinated with HVT). They were challenged intra-abdominally with Marek's disease virus (MDV) and genomic DNA extracted from peripheral blood lymphocytes so that polymorphism of the BLB2/BF2 genes could be analysed using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and nucleotide sequence analysis. 3. A 374-bp fragment of the BLB2 gene was amplified from the samples and, after digesting with restriction enzymes Alu I, Cai I, Cfr I, Hin1 I, Hinf I and Rsa I for RFLP analysis, the 6 electrophoretic patterns were analysed. Seven homozygous genotypes were found and used tentatively to identify alleles of the BLB2 gene. 4. A 765-bp fragment of the BF2 gene was amplified from the 7 samples for cloning and sequencing. 5. Six homozygous birds were confirmed from the sequenced BLB2/BF2 gene. Four birds were resistant to MD. Three birds had identical nucleotide sequences and were highly homologous with MHC haplotype B⁶, which is MD resistant. One bird had high homology with the highly MD-resistant B²¹ haplotype, and two birds were susceptible and highly homologous to the B¹⁹ haplotype, which is highly MD susceptible.

Molecular characterization of the porcine TIM-3 gene

TIM-3 is a member of the TIM (T-cell immunoglobulin domain and mucin domain) family, which plays an important role in TH1 responses and autoimmune diseases. In this study, we cloned and characterized the porcine TIM-3 gene. Real-time PCR showed little expression of porcine TIM-3 in muscle and stomach, low expression in kidney, brain, stomach and muscle, moderate expression in liver, small intestine and lymph, and high expression in spleen and lung. Transient transfection indicated that porcine TIM-3 fusion protein was found to localize on the cell membranes or cytoplasm. Association analysis indicated that the SNP AccI in exon2 was significantly associated (P < 0.05) with red blood cell count mean corpuscular haemoglobin, packed cell volume, Lymphocyte percentage and Lymphocyte modulus. In conclusion, our results provide some information for conducting further studies on the functions of porcine TIM-3 gene in type I diabetes and suggest that SNP AccI in exon2 may be utilized as a marker for molecular-assisted selection in animal breeding.

Bacterial and fungal communities of wilted Italian ryegrass silage inoculated with and without Lactobacillus rhamnosus or Lactobacillus buchneri

AIMS

To understand the effects of lactic acid bacteria (LAB) inoculation on fermentation products, aerobic stability and microbial communities of silage.

METHODS AND RESULTS

Wilted Italian ryegrass was stored in laboratory silos with and without inoculation of Lactobacillus rhamnosus and Lactobacillus buchneri. The silos were opened after 14, 56 and 120 days and then subjected to aerobic deterioration for 7 days. Intensive alcoholic fermentation was found in untreated silage; the sum of ethanol and 2,3-butanediol content at day 14 was about 7 times higher than that of lactic and volatile fatty acids. Alcoholic fermentation was suppressed by L. rhamnosus and L. buchneri inoculation and lactic acid and acetic acid became the dominant fermentation products, respectively. Silages were deteriorated in untreated and L. rhamnosus-inoculated silages, whereas no spoilage was found in L. buchneri-inoculated silage. Enterobacteria such as Erwinia persicina, Pantoea agglomerans and Rahnella aquatilis were detected in untreated silage, whereas some of these bacteria disappeared or became faint with L. rhamnosus treatment. When silage was deteriorated, Lactobacillus brevis and Bacillus pumilus were observed in untreated and L. rhamnosus-inoculated communities, respectively. The inoculated LAB species was detectable in addition to untreated bacterial communities. Saccharomyces cerevisiae and Pichia anomala were the main fungi in untreated and L. rhamnosus-inoculated silages; however, P. anomala was not visibly seen in L. buchneri-inoculated silage either at silo opening or after exposure to air.

CONCLUSION

Inoculation with L. rhamnosus can suppress alcoholic fermentation of wilted grass silage with elimination of enterobacteria at the beginning of fermentation. Addition of L. buchneri may improve aerobic stability, with distinct inhibitory effect observed on P. anomala after silo opening.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bacterial and fungal community analyses help us to understand how inoculated LAB can function to improve the fermentation and aerobic stability of silage.

Comparisons of clinical features of HLA-DRB1*07 positive and negative vitiligo patients in Chinese Han population

BACKGROUND

Human leucocyte antigen (HLA)-II alleles have been found to be associated with vitiligo in different populations, and several studies also suggested that HLA class II alleles/haplotypes were associated with a different type vitiligo. Of HLA class II alleles, DRB1*07 has consistently shown a positive association with vitiligo in Chinese Han population.

OBJECTIVE

To further explore the relationship between DRB1*07 and vitiligo and to evaluate the DRB1*07 effect on the clinical features of vitiligo in Chinese Han population.

METHODS

This study investigated DRB1*07 allele distribution in 1178 unrelated Chinese vitiligo patients and 1743 healthy controls using polymerase chain reaction/sequence specific primer method and observed clinical differences between DRB1*07 positive and DRB1*07 negative patients.

RESULTS

The analysis of the 1178 cases and 1743 controls revealed a highly association between DRB1*07 allele and vitiligo [odds ratio (OR) = 1.97, P = 2.13 × 10(-17) ]. DRB1*07 positive patients had early disease onset (OR = 1.49, P = 0.001), higher frequency of family history (OR = 1.44, P = 0.006) compared with DRB1*07 negative patients.

CONCLUSIONS

The DRB1*07 showed significant association with vitiligo in the study population. This study confirmed that DRB1*07 positive patients had some obvious clinical differences from DRB1*07 negative patients in the Chinese Han population.

Telomerase inhibition strategies by siRNAs against either hTR or hTERT in oral squamous cell carcinoma

Human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) are considered effective molecular targets for current anticancer therapy. In this study, we investigated the therapeutic effects of targeting hTR and hTERT individually or in combination by recombinant adenovirus-delivered small interfering RNA (siRNA) in oral squamous cell carcinoma (OSCC) Tca8113. Further, we screened the optimal strategy for RNA interference. Our results show that these different recombinant adenoviruses specifically reduced the levels of hTR mRNA, hTERT mRNA, hTERT protein and telomerase activity in Tca8113 cells. Moreover, they successfully inhibited xenograft tumor growth in nude mice. The potency of their antitumor activities was ranked as follows: anti-hTR >anti-hTR+anti-hTERT >anti-hTERT. Therefore, we demonstrated that the siRNA-expressing recombinant adenoviruses were an effective anticancer tool for treatment of OSCC. Furthermore, the anticancer effect of solely targeting hTR was more direct and efficient, compared with the effect of targeting hTR and hTERT in combination, or hTERT exclusively. The mechanism of this anticancer effect in OSCC was not only related to the inhibition of cell proliferation and the induction of cell apoptosis, but might also involve the inhibition of tumor angiogenesis.

Predicting treatment effects using biomarker data in a meta-analysis of clinical trials

A biomarker (S) measured after randomization in a clinical trial can often provide information about the true endpoint (T) and hence the effect of treatment (Z). It can usually be measured earlier and more easily than T and as such may be useful to shorten the trial length. A potential use of S is to completely replace T as a surrogate endpoint to evaluate whether the treatment is effective. Another potential use of S is to serve as an auxiliary variable to help provide information and improve the inference on the treatment effect prediction when T is not completely observed. The objective of this report is to focus on its role as an auxiliary variable and to identify situations when S can be useful to increase efficiency in predicting the treatment effect in a new trial in a multiple-trial setting. Both S and T are continuous. We find that higher efficiency gain is associated with higher trial-level correlation but not individual-level correlation when only S, but not T is measured in a new trial; but, the amount of information recovery from S is usually negligible. However, when T is partially observed in the new trial and the individual-level correlation is relatively high, there is substantial efficiency gain by using S. For design purposes, our results suggest that it is often important to collect markers that have high adjusted individual-level correlation with T and at least a small amount of data on T. The results are illustrated using simulations and an example from a glaucoma clinical trial.