Peptide-Based Vaccine against Breast Cancer: Recent Advances and Prospects

Breast cancer is considered the second-leading cancer after lung cancer and is the most prevalent cancer among women globally. Currently, cancer immunotherapy via vaccine has gained great attention due to specific and targeted immune cell activity that creates a potent immune response, thus providing long-lasting protection against the disease. Despite peptides being very susceptible to enzymatic degradation and poor immunogenicity, they can be easily customized with selected epitopes to induce a specific immune response and particulate with carriers to improve their delivery and thus overcome their weaknesses. With advances in nanotechnology, the peptide-based vaccine could incorporate other components, thereby modulating the immune system response against breast cancer. Considering that peptide-based vaccines seem to show remarkably promising outcomes against cancer, this review focuses on and provides a specific view of peptide-based vaccines used against breast cancer. Here, we discuss the benefits associated with a peptide-based vaccine, which can be a mainstay in the prevention and recurrence of breast cancer. Additionally, we also report the results of recent trials as well as plausible prospects for nanotechnology against breast cancer.

The origins, roles and therapies of cancer associated fibroblast in liver cancer

Hepatocellular carcinoma (HCC) is the most common form of liver cancer. It is often preceded by chronic inflammation such as liver fibrosis and cirrhosis. Different cell types are believed to give rise to liver-specific cancer associated fibroblast (CAF), these include resident fibroblast, hepatic stellate cell, liver cancer cell, hepatic sinusoidal endothelial cell and mesenchymal stromal cell. The abundance of fibroblasts has contributed to the cancer progression, immune modulation and treatment resistance in HCC. In this review, we discussed the origins, subtypes and roles of cancer associated fibroblasts in HCC. Their specific roles in shaping the tumor microenvironment, facilitating cancer growth, and modulating different immune cell types to confer a permissive environment for cancer growth. CAF is now an attractive therapeutic target for cancer treatment, however specific therapeutic development in HCC is still lacking. Hence, we have included preclinical and clinical development of CAF-specific interventions for other cancer types in this review. However, most CAF-specific therapies have resulted in disappointing clinical outcomes, likely due to the difficulties in differentiating CAF from normal fibroblast. A thorough understanding of the characteristics and functionalities of CAF is warranted to further improve the therapeutic efficacy of anti-CAF therapies.

Transcriptional analysis highlights three distinct immune profiles of high-risk oral epithelial dysplasia

Oral potentially malignant disorders (OPMD) are precursors of oral squamous cell carcinoma (OSCC), and the presence of oral epithelial dysplasia (OED) in OPMD confers an increased risk of malignant transformation. Emerging evidence has indicated a role for the immune system in OPMD disease progression; however, the underlying immune mechanisms remain elusive. In this study, we used immune signatures established from cancer to delineate the immune profiles of moderate and severe OED, which are considered high-risk OPMD. We demonstrated that moderate and severe OEDs exhibit high lymphocyte infiltration and upregulation of genes involved in both immune surveillance (major histocompatibility complex-I, T cells, B cells and cytolytic activity) and immune suppression (immune checkpoints, T regulatory cells, and tumor-associated macrophages). Notably, we identified three distinct subtypes of moderate and severe OED: immune cytotoxic, non-cytotoxic and non-immune reactive. Active immune surveillance is present in the immune cytotoxic subtype, whereas the non-cytotoxic subtype lacks CD8 immune cytotoxic response. The non-immune reactive subtype showed upregulation of genes involved in the stromal microenvironment and cell cycle. The lack of T cell infiltration and activation in the non-immune reactive subtype is due to the dysregulation of CTNNB1, PTEN and JAK2. This work suggests that moderate and severe OED that harbor the non-cytotoxic or non-immune reactive subtype are likely to progress to cancer. Overall, we showed that distinct immune responses are present in high-risk OPMD, and revealed targetable pathways that could lead to potential new approaches for non-surgical management of OED.

DNA Vaccines Targeting Novel Cancer-Associated Antigens Frequently Expressed in Head and Neck Cancer Enhance the Efficacy of Checkpoint Inhibitor

HPV-independent head and neck squamous cell carcinoma (HNSCC) is a common cancer globally. The overall response rate to anti-PD1 checkpoint inhibitors (CPIs) in HNSCC is ~16%. One major factor influencing the effectiveness of CPI is the level of tumor infiltrating T cells (TILs). Converting TILlow tumors to TILhigh tumors is thus critical to improve clinical outcome. Here we describe a novel DNA vaccines to facilitate the T-cell infiltration and control tumor growth. We evaluated the expression of target antigens and their respective immunogenicity in HNSCC patients. The efficacy of DNA vaccines targeting two novel antigens were evaluated with or without CPI using a syngeneic model. Most HNSCC patients (43/44) co-expressed MAGED4B and FJX1 and their respective tetramer-specific T cells were in the range of 0.06-0.12%. In a preclinical model, antigen-specific T cells were induced by DNA vaccines and increased T cell infiltration into the tumor, but not MDSC or regulatory T cells. The vaccines inhibited tumor growth and improved the outcome alone and upon combination with anti-PD1 and resulted in tumor clearance in approximately 75% of mice. Pre-existence of MAGED4B and FJX1-reactive T cells in HNSCC patients suggests that these widely expressed antigens are highly immunogenic and could be further expanded by vaccination. The DNA vaccines targeting these antigens induced robust T cell responses and with the anti-PD1 antibody conferring excellent tumor control. This opens up an opportunity for combination immunotherapy that might benefit a wider population of HNSCC patients in an antigen-specific manner.

911 Immune profiling reveals enrichment of distinct immune signatures in high-risk oral potentially malignant disorders

Background

Patients with oral potentially malignant disorders (OPMD) having moderate or severe oral epithelial dysplasia (OED) have a greater risk of developing oral squamous cell carcinoma (OSCC) compared to mild OED with an odds ratio of 2.4.1 The involvement of specific immune cell types associated with malignant transformation have been reported, giving rise to clinical trials in immunoprevention. However, the immune landscape of OPMD remains understudied. In this study, we aimed to elucidate the immune landscape of high-risk OPMD by transcriptomic profiling for the identification of potential immunoprevention strategy.

Methods

Histological evaluation was performed on hematoxylin and eosin (H&E)-stained tissues to investigate the differences of lymphocyte infiltration in benign lesions (n=16), high-risk OPMD consisted of moderate and severe OED (n=46) and early-stage OSCC (n=6). Formalin-fixed paraffin-embedded tissue sections of selected cases from each sample type were subjected to RNA sequencing. Weighted-gene-correlation network analysis (WGCNA) was used to identify key gene modules expressed in specific disease type.2 The immune landscape of high-risk OPMD was elucidated by the enrichment of immune signatures using single-sample gene set enrichment analysis.3–5 The response of high-risk OPMD to anti-PD1 treatment was predicted by the detection of T-cell-inflamed condition.6 Validation was performed by multiplex immunofluorescent (mIF) staining.

Results

Our H&E evaluation showed that lymphocyte infiltration into the epithelial was seen in 80% of high-risk OPMD and early-stage OSCC, compared to 9% of benign lesion. Gene modules identified from WGCNA analysis revealed that genes involved in immune-related pathways were overexpressed in high-risk OPMD and in early-stage OSCC when compared to benign lesion, but unchanged between high-risk OPMD and early-stage OSCC. We further demonstrated that immune signatures representing lymphocyte infiltration, MHC-I antigen presentation and cytotoxic immune responses were enriched in high-risk OPMD, indicating the presence of immune surveillance. High-risk OPMD can be grouped into the T-cell-inflamed and non-immune reactive subtypes. The T-cell-inflamed subtype is enriched with T cells, interferon signaling and PD-1/PD-L1 immune checkpoint proteins, suggesting that these lesions may be amenable to anti-PD1 treatment. Meanwhile, the non-immune reactive subtype demonstrated low enrichment in signatures for immune cell infiltration, indicating a need of intervention to induce lymphocyte infiltration. Using mIF staining, we observed an increase of CD45+ immune cell population expressing PD-L1 in high-risk OPMD.

Conclusions

Immune surveillance is a prominent feature of high-risk OPMD. However, different subsets of high-risk OPMD exist, suggesting a need of different immunoprevention approaches to prevent disease progression which warrants further investigation.

Acknowledgements

This study was supported and funded by the Global Challenge Research Fund by the Medical Research Council, UK (MR/P024351/1) and Cancer Research Malaysia. We thank the Ong Heng Tiang & Ong Sek Pek Foundation for scholarship sponsorship.

References

Iocca O, Sollecito TP, Alawi F, et al. Potentially malignant disorders of the oral cavity and oral dysplasia: a systematic review and meta-analysis of malignant transformation rate by subtype. Head Neck 2020;42:539–55.

Langfelder P, Horvath S. WGCNA: an R package for weighted correlation network analysis. BMC Bioinformatics 2008;9:559.

Subramanian A, Tamayo P, Mootha VK, et al. Gene set enrichment analysis: a knowledge-based approach for interpreting genome-wide expression profiles. Proc Natl Acad Sci U S A. 2005;102:15545–50.

Chen YP, Wang YQ, Lv JW, et al. Identification and validation of novel microenvironment-based immune molecular subgroups of head and neck squamous cell carcinoma: implications for immunotherapy. Ann Oncol 2019;30:68–75.

Thorsson V, Gibbs DL, Brown SD, et al. The immune landscape of cancer. Immunity 2018;48:812–30.

Ayers M, Lunceford J, Nebozhyn M, et al. IFN-gamma-related mRNA profile predicts clinical response to PD-1 blockade. J Clin Invest 2017;127:2930–40.

Ethics Approval

The use of clinical specimens in this study has been approved by the Medical Ethics Committee, Faculty of Dentistry, University of Malaya [DF OS1624/0073(L)], and The National Medical Research Register, Malaysia [NMRR-16-1764-32566 (IIR)].

HER2/neu-Based Peptide Vaccination-Pulsed with B-Cell Epitope Induced Efficient Prophylactic and Therapeutic Antitumor Activities in TUBO Breast Cancer Mice Model

Breast cancer is the most common invasive cancer diagnosed among women. A cancer vaccine has been recognized as a form of immunotherapy with a prominent position in the prevention and treatment of breast cancer. The majority of current breast cancer vaccination strategies aim to stimulate antitumor T-cell responses of the HER2/neu oncogene, which is abnormally expressed in breast cancer cells. However, the role of the B-cell humoral response is often underappreciated in the cancer vaccine design. We have advanced this idea by elucidating the role of B-cells in cancer vaccination by designing a chimeric antigenic peptide possessing both cytotoxic T lymphocytes (GP2) and B-cell (P4) peptide epitopes derived from HER2/neu. The chimeric peptide (GP2-P4) was further conjugated to a carrier protein (KLH), forming a KLH-GP2-P4 conjugate. The immunogenicity of KLH-GP2-P4 was compared with KLH-GP2 (lacking the B-cell epitope) in BALB/c mice. Mice immunized with KLH-GP2-P4 elicited more potent antigen-specific neutralizing antibodies against syngeneic TUBO cells (cancer cell line overexpressing HER2/neu) that was governed by a balanced Th1/Th2 polarization in comparison to KLH-GP2. Subsequently, these immune responses led to greater inhibition of tumor growth and longer survival in TUBO tumor-bearing mice in both prophylactic and therapeutic challenge experiments. Overall, our data demonstrated that the B-cell epitope has a profound effect in orchestrating an efficacious antitumor immunity. Thus, a multi-epitope peptide vaccine encompassing cytotoxic T-lymphocytes, T-helper and B-cell epitopes represents a promising strategy in developing cancer vaccines with a preventive and therapeutic modality for the effective management of breast cancer.

Monitoring T Cells Responses Mounted by Therapeutic Cancer Vaccines

With the regulatory approval of Provenge and Talimogene laherparepvec (T-VEC) for the treatment of metastatic prostate cancer and advanced melanoma respectively, and other promising clinical trials outcomes, cancer vaccine is gaining prominence as a cancer therapeutic agent. Cancer vaccine works to induce T cell priming, expansion, and infiltration resulting in antigen-specific cytotoxicity. Such an approach that can drive cytotoxicity within the tumor could complement the success of checkpoint inhibitors as tumors shown to have high immune cell infiltration are those that would respond well to these antibodies. With the advancements in cancer vaccine, methods to monitor and understand how cancer vaccines modify the immune milieu is under rapid development. This includes using ELISpot and intracellular staining to detect cytokine secretion by activated T cells; tetramer and CyTOF to quantitate the level of antigen specific T cells; proliferation and cell killing assay to detect the expansion of T cell and specific killing activity. More recently, T cell profiling has provided unprecedented detail on immune cell subsets and providing clues to the mechanism involved in immune activation. Here, we reviewed cancer vaccines currently in clinical trials and highlight available techniques in monitoring the clinical response in patients.

Label-Free, High-Throughput Assay of Human Dendritic Cells from Whole-Blood Samples with Microfluidic Inertial Separation Suitable for Resource-Limited Manufacturing

Microfluidics technology has not impacted the delivery and accessibility of point-of-care health services, like diagnosing infectious disease, monitoring health or delivering interventions. Most microfluidics prototypes in academic research are not easy to scale-up with industrial-scale fabrication techniques and cannot be operated without complex manipulations of supporting equipment and additives, such as labels or reagents. We propose a label- and reagent-free inertial spiral microfluidic device to separate red blood, white blood and dendritic cells from blood fluid, for applications in health monitoring and immunotherapy. We demonstrate that using larger channel widths, in the range of 200 to 600 µm, allows separation of cells into multiple focused streams, according to different size ranges, and we utilize a novel technique to collect the closely separated focused cell streams, without constricting the channel. Our contribution is a method to adapt spiral inertial microfluidic designs to separate more than two cell types in the same device, which is robust against clogging, simple to operate and suitable for fabrication and deployment in resource-limited populations. When tested on actual human blood cells, 77% of dendritic cells were separated and 80% of cells remained viable after our assay.

Abstract 1466: Combination immunotherapy successfully control tumor growth in a transgenic mouse model

The use of checkpoint inhibitor anti-PD1 has achieved significant clinical benefit, in recurrent and metastatic head and neck cancer patients, where the overall response rate is between 16-20%. The use of antigen-specific cancer vaccine to increase the level of cytotoxic T cells is believed to work synergistically with anti-PD1. In this study, we evaluated the efficacy of antigen-specific DNA vaccine when it’s used in combination with anti-PD1. The B6.Cg-Tg(HLA-A/H2-D)2Enge/J mice bearing established tumours overexpressing the tumour antigen were vaccinated either with anti-PD1, DNA vaccine or anti-PD1 in combination with DNA vaccine. Tumour volume was monitored and antigen-specific immune responses were evaluated at the endpoint. Our data demonstrated DNA vaccine induced antigen-specific immune responses and animals vaccinated with DNA vaccine harboured smaller tumour volume compared to controls. Significantly, animals that received DNA vaccine expressed consistently higher levels IFN-γ and resulted in the upregulation of PD1 compared to control animals. We then demonstrated mice vaccinated with both DNA vaccine and anti-PD1 had near to complete tumour control, indicating a synergistic effect of DNA vaccine with anti-PD1. Animals treated with DNA vaccine in combination with anti-PD1 also have better overall survival. Importantly, these animals showed increased antigen-specific responses by the ELISPOT assay. In summary, our data suggest antigen-specific DNA vaccine works synergistically with anti-PD1 and conferred an excellent tumour control; this opens up a new opportunity of combinatory immunotherapy that might benefit a wider population of patients in an antigen-specific manner.

Citation Format: Kue Peng Lim, Syafinaz Zainal, Natasha Zulaziz, Chai Phei Gan, San Jiun Chai, Bryan Kit Weng Lye, Chuan Wang, Ruhcha V. Sutavani, Christian Ottensmeier, Emma King, Gareth Thomas, Natalia Savelyeva, Sok Ching Cheong. Combination immunotherapy successfully control tumor growth in a transgenic mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1466.

Pseudohypoparathyroidism: A case of hypocalcemia and hypothyroidism diagnosed during the postpartum period

We describe a 29-year-old Para 1 post-Emergency Lower Segment Caesarean Section (EMLSCS) for fetal distress and Preterm Rupture of the Membrane (PROM) referred by the Obstetric team for persistent bradycardia. She had the typical features of Albright's Hereditary Osteodystrophy (AHO). The laboratory investigation revealed hypocalcemia, hyperphosphatemia with a high Parathyroid hormone (PTH) level and low free Thyroxine 4 (fT4) with high Thyroid Stimulating Hormone (TSH). The patient was diagnosed with Pseudohypoparathyroidism (PHP) Type 1A associated with TSH resistance based on the somatic features of AHO present as well as biochemical and radiological abnormalities.

In vitro evaluation of dual-antigenic PV1 peptide vaccine in head and neck cancer patients

Peptide vaccines derived from tumour-associated antigens have been used as an immunotherapeutic approach to induce specific cytotoxic immune response against tumour. We previously identified that MAGED4B and FJX1 proteins are overexpressed in HNSCC patients; and further demonstrated that two HLA-A2-restricted 9-11 amino acid peptides derived from these proteins were able to induce anti-tumour immune responses in vitro independently using PBMCs isolated from these patients. In this study, we evaluated the immunogenicity and efficacy of a dual-antigenic peptide vaccine (PV1), comprised of MAGED4B and FJX1 peptides in HNSCC patients. We first demonstrated that 94.8% of HNSCC patients expressed MAGED4B and/or FJX1 by immunohistochemistry, suggesting that PV1 could benefit the majority of HNSCC patients. The presence of pre-existing MAGED4B and FJX1-specific T-cells was detected using a HLA-A2 dimer assay and efficacy of PV1 to induce T-cell to secrete cytotoxic cytokine was evaluated using ELISPOT assay. Pre-existing PV1-specific T-cells were detected in all patients. Notably, we demonstrated that patients' T-cells were able to secrete cytotoxic cytokines upon exposure to target cells expressing the respective antigen post PV1 stimulation. Furthermore, patients with high expression of MAGED4B and FJX1 in their tumours were more responsive to PV1 stimulation, demonstrating the specificity of the PV1 peptide vaccine. Additionally, we also demonstrated the expression of MAGED4B and FJX1 in breast, lung, colon, prostate and rectal cancer suggesting the potential use of PV1 in these cancers. In summary, PV1 could be a good vaccine candidate for the treatment of HNSCC patients and other cancers expressing these antigens.

Genetically-defined novel oral squamous cell carcinoma cell lines for the development of molecular therapies

Emerging biological and translational insights from large sequencing efforts underscore the need for genetically-relevant cell lines to study the relationships between genomic alterations of tumors, and therapeutic dependencies. Here, we report a detailed characterization of a novel panel of clinically annotated oral squamous cell carcinoma (OSCC) cell lines, derived from patients with diverse ethnicity and risk habits. Molecular analysis by RNAseq and copy number alterations (CNA) identified that the cell lines harbour CNA that have been previously reported in OSCC, for example focal amplications in 3q, 7p, 8q, 11q, 20q and deletions in 3p, 5q, 8p, 18q. Similarly, our analysis identified the same cohort of frequently mutated genes previously reported in OSCC including TP53, CDKN2A, EPHA2, FAT1, NOTCH1, CASP8 and PIK3CA. Notably, we identified mutations (MLL4, USP9X, ARID2) in cell lines derived from betel quid users that may be associated with this specific risk factor. Gene expression profiles of the ORL lines also aligned with those reported for OSCC. By focusing on those gene expression signatures that are predictive of chemotherapeutic response, we observed that the ORL lines broadly clustered into three groups (cell cycle, xenobiotic metabolism, others). The ORL lines noted to be enriched in cell cycle genes responded preferentially to the CDK1 inhibitor RO3306, by MTT cell viability assay. Overall, our in-depth characterization of clinically annotated ORL lines provides new insight into the molecular alterations synonymous with OSCC, which can facilitate in the identification of biomarkers that can be used to guide diagnosis, prognosis, and treatment of OSCC.

Induction of fibroblast senescence generates a non-fibrogenic myofibroblast phenotype that differentially impacts on cancer prognosis

Cancer-associated fibroblasts (CAF) remain a poorly characterized, heterogeneous cell population. Here we characterized two previously described tumor-promoting CAF sub-types, smooth muscle actin (SMA)-positive myofibroblasts and senescent fibroblasts, identifying a novel link between the two. Analysis of CAF cultured ex vivo, showed that senescent CAF are predominantly SMA-positive; this was confirmed by immunochemistry in head & neck (HNSCC) and esophageal (EAC) cancers. In vitro, we found that fibroblasts induced to senesce develop molecular, ultrastructural and contractile features typical of myofibroblasts and this is dependent on canonical TGF-β signaling. Similar to TGF-β1-generated myofibroblasts, these cells secrete soluble factors that promote tumor cell motility. However, RNA-sequencing revealed significant transcriptomic differences between the two SMA-positive CAF groups, particularly in genes associated with extracellular matrix (ECM) deposition and organization, which differentially promote tumor cell invasion. Notably, second harmonic generation imaging and bioinformatic analysis of SMA-positive human HNSCC and EAC showed that collagen fiber organization correlates with poor prognosis, indicating that heterogeneity within the SMA-positive CAF population differentially impacts on survival. These results show that non-fibrogenic, SMA-positive myofibroblasts can be directly generated through induction of fibroblast senescence and suggest that senescence and myofibroblast differentiation are closely linked processes.

Resection of a physeal bar with complete transverse osteotomy at the metaphysis and Ilizarov external fixation

The traditional techniques involving an oblique tunnel or triangular wedge resection to approach a central or mixed-type physeal bar are hindered by poor visualisation of the bar. This may be overcome by a complete transverse osteotomy at the metaphysis near the growth plate or a direct vertical approach to the bar. Ilizarov external fixation using small wires allows firm fixation of the short physis-bearing fragment, and can also correct an associated angular deformity and permit limb lengthening. We accurately approached and successfully excised ten central- or mixed-type bars; six in the distal femur, two in the proximal tibia and two in the distal tibia, without damaging the uninvolved physis, and corrected the associated angular deformity and leg-length discrepancy. Callus formation was slightly delayed because of periosteal elevation and stretching during resection of the bar. The resultant resection of the bar was satisfactory in seven patients and fair in three as assessed using a by a modified Williamson-Staheli classification.

Abstract A158: MAGED4B specific peptides: Short or long or combination?

Immunotherapy has emerged as one of the most efficacious form of cancer therapy. We have previously demonstrated MAGED4B short peptides are efficacious in inducing patients' immune responses in vitro. However, effective vaccination against tumours requires generation of both CD8+ and CD4+ T-cell responses. A critical role of CD4+ helper T cells in the development of CD8+ tumour-specific effector function has been shown by numerous studies. In this pilot study, we aim to compare the efficacy of MAGED4B specific-short peptides (SP), long peptide (LP) and the combination of both short and long peptides in inducing patients' immune responses in vitro. Briefly, peripheral blood mononuclear cells (PBMC) from HLA-A2 positive healthy volunteers were incubated with 10 μg/ml of peptide in the presence of IL-2 and IL-7 for 7 days; peptide exposed PBMC were then incubated with cancer cells expressing MAGED4B overnight. Capability of T cells to secrete IFN-γ was accessed using ELISPOT assay and CEF peptides pool was used as positive control. Our data demonstrated that all MAGED4B peptides (short and long) are capable to induce similar and/or higher cytokine secretion compared to CEF peptides pool suggesting that these peptides are highly immunogenic. MAGED4B specific SP are better in inducing cytolytic activity compared to MAGED4B specific LP; however when both LP and SP were mixed as a cocktail, we observed a reduction in cytokine secreting T cells when the immune cells were co-incubated with MAGED4B expressing cell line, advocating an inhibition instead of synergizing reaction. In summary, our data has corroborated our previous finding that HLA-A2 restricted MAGED4B specific SP are immunogenic. However, we did not observed a synergistic event when SP and LP were used in a cocktail, questioning the combinatorial effect of CD4+ and CD8+ T cells. These preliminary findings would need to be validated in a bigger cohort of patients.

Citation Format: Kue Peng Lim, Ai Leng Chun, Sathibalan Ponniah, Sok Ching Cheong. MAGED4B specific peptides: Short or long or combination? [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A158.

Identification of Four-Jointed Box 1 (FJX1)-Specific Peptides for Immunotherapy of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is highly prevalent in South East Asia and China. The poor outcome is due to late presentation, recurrence, distant metastasis and limited therapeutic options. For improved treatment outcome, immunotherapeutic approaches focusing on dendritic and autologous cytotoxic T-cell based therapies have been developed, but cost and infrastructure remain barriers for implementing these in low-resource settings. As our prior observations had found that four-jointed box 1 (FJX1), a tumor antigen, is overexpressed in NPCs, we investigated if short 9-20 amino acid sequence specific peptides matching to FJX1 requiring only intramuscular immunization to train host immune systems would be a better treatment option for this disease. Thus, we designed 8 FJX1-specific peptides and implemented an assay system to first, assess the binding of these peptides to HLA-A2 molecules on T2 cells. After, ELISPOT assays were used to determine the peptides immunogenicity and ability to induce potential cytotoxicity activity towards cancer cells. Also, T-cell proliferation assay was used to evaluate the potential of MHC class II peptides to stimulate the expansion of isolated T-cells. Our results demonstrate that these peptides are immunogenic and peptide stimulated T-cells were able to induce peptide-specific cytolytic activity specifically against FJX1-expressing cancer cells. In addition, we demonstrated that the MHC class II peptides were capable of inducing T-cell proliferation. Our results suggest that these peptides are capable of inducing specific cytotoxic cytokines secretion against FJX1-expressing cancer cells and serve as a potential vaccine-based therapy for NPC patients.

Identification of immunogenic MAGED4B peptides for vaccine development in oral cancer immunotherapy

The ever-increasing number of tumor-associated antigens has provided a major stimulus for the development of therapeutic peptides vaccines. Tumor-associated peptides can induce high immune response rates and have been developed as vaccines for several types of solid tumors, and many are at various stages of clinical testing. MAGED4B, a melanoma antigen, is overexpressed in oral squamous cell carcinoma (OSCC) and this expression promotes proliferation and cell migration. In this study, we have identified 9 short peptides derived from MAGED4B protein that are restricted in binding to the HLA subtypes common in the Asian population (HLA-A2, A11, and A24). The peptides had good binding affinity with the MHC-Class I molecules and stimulated ex-vivo IFN-gamma and Granzyme-B production in blood samples from OSCC patients, suggesting that they are immunogenic. Further, T cells stimulated with peptide-pulsed dendritic cells showed enhanced T-cell cytotoxic activity against MAGED4B-overexpressing OSCC cell lines. In summary, we have identified MAGED4B peptides that induce anti-tumor immune responses advocating that they could be further developed as vaccine candidates for the treatment of OSCC.

Penicillium marneffei infection in a lung transplant recipient

Penicillium marneffei is a thermally dimorphic fungus that can cause severe opportunistic infections in endemic regions of Southeast Asia, particularly in individuals infected with human immunodeficiency virus-1, but has rarely been reported in solid organ transplant recipients. Herein, we report the first case, to our knowledge, of P. marneffei infection in a lung transplant recipient, occurring in a 41-year-old woman 28 months post lung transplantation, after recent travel to Vietnam. We have reviewed the literature to derive some management principles for this rare infection in this clinical context. The number of P. marneffei infections in transplant recipients may increase, as a result of increasing rates of transplantation and travel to endemic areas.

CD4+CD25hiCD127low regulatory T cells are increased in oral squamous cell carcinoma patients

Regulatory T cells (Tregs), a subset of CD4+ T cells plays a pivotal role in regulating the immune system. An increase in Treg numbers enables cancer progression by dampening the immune system and allowing tumor cells to evade immune detection and destruction. An increase in Treg numbers and expression of inhibitory cytokines including TGF-β and IL-10 are mechanisms by which Tregs exert their immune suppressive function. However, the presence of Tregs and inhibitory cytokines in oral cancer patients is still unclear. In this study, the presence of circulating Tregs in 39 oral cancer patients and 24 healthy donors was examined by studying the presence of the CD4+CD25hiCD127low cell population in their peripheral blood mononuclear cells using flow cytometry. Serum levels of TGF-β and IL-10 were measured by ELISA. T cell subsets of OSCC patients were found to differ significantly from healthy donors where a decrease in CD8+ cytotoxic T cells and an increase in Tregs (CD4+CD25hiCD127low) were observed. Further, the ratio of CD8+ T cells/Tregs was also decreased in patients compared to healthy donors. The presence of Tregs was accompanied by a decrease in IL-10 but not TGF-β secretion in OSCC patients when compared to donors; in addition, the analysis also revealed that an increased presence of Tregs was accompanied by better patient survival. Amongst OSCC patients, smokers had significantly higher levels of TGF-β. It is apparent that the immune system is compromised in OSCC patients and the characterization of the Treg subpopulation could form a basis for improving our understanding of the perturbations in the immune system that occur during OSCC tumorigenesis.

Abstract 1573: MAGED4B drives oral carcinogenesis and is a promising peptide vaccine target for the treatment of oral squamous cell carcinoma

MAGED4B is a member of the Melanoma Antigen Gene (MAGE) family. We demonstrated that MAGED4B is over-expressed in more than 50% of oral squamous cell carcinoma (OSCC) tissues and that the expression of MAGED4B is associated with lymph node metastasis and poor disease specific survival. OSCC cell lines over-expressing MAGED4B exhibited an increase in cell growth both in vitro and in vivo, and were significantly more resistant to UV-induced apoptosis compared to control cells, suggesting a role for MAGED4B in modulating cell death. Further, MAGED4B also promoted cell migration. MAGE proteins are good targets for cancer immunotherapy as they are highly immunogenic. We identified and synthesized MAGED4B peptides that were HLA-A2- specific and tested the ability of these peptides to generate an anti-tumour response using PBMCs from OSCC patients and healthy individuals. Firstly, the PBMC samples obtained from patients and healthy individuals were tested for HLA-A2 expression. Positive samples were analyzed for peptide-specific stimulation of IFN-γ and granzyme secretion ex-vivo via ELISPOT assay. Dendritic cells pulsed with these peptides were used to stimulate PBMC cultures, and were studied for IFN-γ and granzyme secretion. In parallel, the binding of the peptides to the MHC-Class I molecule was determined by the binding assay. Further, the ability of these bound peptides to interact with T cells was measured by the dimer assay. We demonstrated that all the peptides have good binding capacity with the MHC-Class I molecules. Moreover, the binding of these peptides on MHC-Class I molecules could attract and further interact with T cells. Notably, the PBMC stimulated once with peptide-pulsed dendritic cells or twice with peptide and peptide-pulsed dendritic cells showed peptide-specific cytotoxic activity against MAGED4B-expressing OSCC cell lines. In summary, we first demonstrated that MAGED4B drives oral carcinogenesis and second, showed that MAGED4B-specific peptides are apable of inducing anti-tumour specific immune responses. Taken together, this indicates that MAGED4B could be a promising peptide vaccine target for the treatment of OSCC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1573. doi:1538-7445.AM2012-1573

Abstract 4118: Fibroblast heterogeneity in oral squamous cell carcinoma is directed by tumor epithelium and promotes keratinocyte invasion in vitro

The transformation of human cells requires the accumulation of a broad spectrum of genetic abnormalities that typically lead to unrestrained cell growth. It has now become clear that alterations extrinsic to the tumor cell are also required and there is a considerable body of evidence to show that the cancer microenvironment plays a pivotal role in the initiation, progression and spread of cancer. In this study, we show that fibroblasts isolated from keratinocyte cultures of normal oral mucosa, epithelial dysplasia and mortal and immortal oral squamous cell carcinomas (OSCC) were heterogeneous and, using global gene expression profiling, could be grouped according to their tissue of origin. Fibroblasts from immortal OSCC, for example, showed high levels of activation and were characterized by down regulation of cell cycle-related genes and up-regulation of transmembrane-related genes. The data was validated using real time quantitative PCR to examine the expression of specific up-regulated (IGFBP7, ITGA6, p21) and down-regulated (FOXM1, MCM7) genes identified as having significant fold change in the expression analyses. Further, we examined the inter-relationship between tumor epithelial cells and tumor-associated fibroblasts. Whilst the proliferation of two target keratinocyte cell lines was stimulated by conditioned media from both normal and tumor-associated fibroblasts (in excess of keratinocyte growth in 10% serum), only fibroblasts from immortal OSCC stimulated the invasion of a non-tumorigenic keratinocyte cell line into fibroblast-rich collagen gels in organotypic cultures. Keratinocyte conditioned media stimulated the growth and activation of fibroblasts from normal oral mucosa and mortal OSCC. The results demonstrate a close inter-relationship between tumor epithelium and tumor-associated fibroblasts and show that the diversity of fibroblasts during tumor progression is not only influenced by the tumor epithelium but also, has biological significance in the promotion of tumor cell invasion in vitro.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4118.

Interaction force measurements for the design of tissue adhesives

Synthesis of tissue adhesives had been carried out in various laboratories in the past decades but the development is currently stalled. One of the key reasons, it is believed, is that researchers have not fully understood and resolved the role of the functional groups that are responsible for good adhesion to biological tissues. Further progress in synthesis is significantly hindered without this fundamental understanding. With this aim in mind, atomic force microscopy (AFM) has been exploited in this work to study the interactions between functional groups that are common to biological tissues. In this work, the AFM tip and substrates were functionalized and used to measure the non-specific interaction among these common functional groups. The ultimate aim of the study is to calculate the interaction force between a single pair of functional groups. A novel calculation method based on the AFM data and probe geometry is presented. The results provide insights into the strength of the bond between different functional groups and the could serve as a guide in selecting the appropriate functional groups in tissue adhesive synthesis. This method could be further applied to studies involving interfaces of biomedical devices where intermolecular interactions are of concern.

MDM2 SNP309 does not confer an increased risk to oral squamous cell carcinoma but may modulate the age of disease onset

The MDM2 SNP309 has been associated with increased expression of the protein which could suppress p53 function, and has been shown to modulate risk to cancer. We have previously shown that overexpression of MDM2 is a common event in oral cancers. In the present study, we determined the association between the MDM2 SNP309 polymorphism and oral cancer in 207 oral cancer patients and 116 normal subjects. We genotyped the MDM2 SNP309 by PCR-RFLP. Logistic regression was adapted to calculate odds ratios for MDM2 SNP309 polymorphism from univariate and multivariable adjusted models. Our results suggest that MDM2 SNP309 does not confer increased risk to oral cancer (OR=1.55, 95% CI=0.77-3.11). However, the GG/TG genotype was associated with later disease onset in women above 55 years of age. Collectively, our data suggests that MDM2 SNP309 may modulate the risk to oral cancer and is a modifier of the age at oral cancer onset in women above the age of 55 years.

HPV infection and the alterations of the pRB pathway in oral carcinogenesis

Inactivation of the retinoblastoma (pRB) pathway is a common event in oral squamous cell carcinoma particularly through the aberrant expression of the components within this pathway. This study examines the alterations of molecules within the pRB pathway by looking at the presence of homozygous deletions in p16(INK4A) and the expression patterns of pRB, cyclin D1 and CDK4, as well as the presence of human papillomavirus (HPV) in our samples. In our study, 5/20 samples demonstrated deletions of p16(INK4A) exon 1alpha. pRB overexpression was found in 20/20 samples, the expression was mainly observed in all layers of the epithelia, particularly in the basal layer where cells are actively dividing and aberrant pRB expression was found in 12/20 samples. Cyclin D1 and CDK4 overexpression was detected in 6/20 and 2/20 samples respectively in comparison to hyperplasias where both proteins were either not expressed or expressed at minimal levels (<10%). Strikingly, HPV was found to be present in all of our samples, suggesting that HPV plays a significant role in driving oral carcinogenesis. Notably, 17/20 of our samples showed more than one alteration in the pRB pathway, however, we did not find any significant relationship between the presence of HPV, homozygous deletion of p16(INK4A) and overexpression of pRB, cyclin D1 and CDK4. Collectively, this data demonstrates that alterations in the pRB pathway are a common event and involve the aberration of more than one molecule within the pathway. Furthermore, the involvement of HPV in all our samples suggests that HPV infection may play an important role in oral carcinogenesis.

Establishment and characterization of Asian oral cancer cell lines as in vitro models to study a disease prevalent in Asia

We have established 3 cell lines ORL-48, -115 and -136 from surgically resected specimens obtained from untreated primary human oral squamous cell carcinomas of the oral cavity. The in vitro growth characteristics, epithelial origin, in vitro anchorage independency, human papilloma-virus (HPV) infection, microsatellite instability status, karyotype and the status of various cell cycle regulators and gatekeepers of these cell lines were investigated. All 3 cell lines grew as monolayers with doubling times ranging between 26.4 and 40.8 h and were immortal. Karyotyping confirmed that these cell lines were of human origin with multiple random losses and gains of entire chromosomes and regions of chromosomes. Immunohistochemistry staining of cytokeratins confirmed the epithelial origin of these cell lines, and the low degree of anchorage independency expressed by these cell lines suggests non-transformed phenotypes. Genetic analysis identified mutations in the p53 gene in all cell lines and hypermethylation of p16INK4a in ORL-48 and -136. Analysis of MDM2 and EGFR expression indicated MDM2 overexpression in ORL-48 and EGFR overexpression in ORL-136 in comparison to the protein levels in normal oral keratinocytes. Analysis of the BAT-26 polyadenine repeat sequence and MLH-1 and MSH-2 repair enzymes demonstrated that all 3 cell lines were microsatellite stable. The role of HPV in driving carcinogenesis in these tumours was negated by the absence of HPV. Finally, analysis of the tissues from which these cell lines were derived indicated that the cell lines were genetically representative of the tumours, and, therefore, are useful tools in the understanding of the molecular changes associated with oral cancers.

Alterations of the p14ARF-p53-MDM2 pathway in oral squamous cell carcinoma: MDM2 overexpression is a common event

The majority of global incidences of oral cancer occur in Asia, and the aetiology of oral cancer is different in Asia as it is in the West. However, whereas there is a growing understanding of the molecular mechanisms of oral cancer progression in the West, there is little progress in this understanding in Asia. In particular, the role of the p53 pathway in modulating cancer progression in Asian oral cancer remains unclear. In this study, we micro-dissected and analysed 20 well-differentiated oral squamous cell carcinoma specimens for alterations in the p53 pathway. We found that 6/20 samples contained mutations in the p53 gene which occurred in three hotspots, at codon 203, 218 and 296. Furthermore, 6/20 samples had a homozygous deletion of p14ARF, but notably p14ARF deletion and p53 mutation events were often independent and mutually exclusive. Strikingly, MDM2 was upregulated in 20/20 samples, but not in 3/3 normal tissue specimens. Taken together, these data suggest that inactivation of the p53 pathway is a frequent event in oral squamous cell carcinoma, which occurs by an aberration in one of a number of players in the p53 pathway.

Penile metastasis: an unusual presentation of metastatic colonic cancer

We report here an interesting presentation of a primary colonic carcinoma in a urological setting. A previously unknown case of colonic carcinoma presented with a lesion in the glans penis which was later diagnosed as a secondary deposit from colonic cancer. Penile involvement has been implicated as a metastatic site in several tumours. Although uncommon, this presentation is not unknown. A literature review of this unusual presentation has been performed and is summarised in the article

Further identification and characterization of novel intermediate and mature cleavage products released from the ORF 1b region of the avian coronavirus infectious bronchitis virus 1a/1b polyprotein

The coronavirus 3C-like proteinase is one of the viral proteinases responsible for processing of the 1a and 1a/1b polyproteins to multiple mature products. In cells infected with avian coronavirus infectious bronchitis virus (IBV), three proteins of 100, 39, and 35 kDa, respectively, were previously identified as mature cleavage products released from the 1b region of the 1a/1b polyprotein by the 3C-like proteinase. In this report, we show the identification of two more cleavage products of 68 and 58 kDa released from the same region of the polyprotein. In addition, two stable intermediate cleavage products with molecular masses of 160 and 132 kDa, respectively, were identified in IBV-infected cells. The 160-kDa protein was shown to be an intermediate cleavage product covering the 100- and 68-kDa proteins, and the 132-kDa protein to be an intermediate cleavage product covering the 58-, 39-, and 35-kDa proteins. Immunofluorescent staining of IBV-infected cells and cells expressing individual cleavage products showed that the 100-, 68-, and 58-kDa proteins were associated with the membranes of the endoplasmic reticulum, and the 39- and 35-kDa proteins displayed diffuse distribution patterns.

The missing link in coronavirus assembly. Retention of the avian coronavirus infectious bronchitis virus envelope protein in the pre-Golgi compartments and physical interaction between the envelope and membrane proteins

One missing link in the coronavirus assembly is the physical interaction between two crucial structural proteins, the membrane (M) and envelope (E) proteins. In this study, we demonstrate that the coronavirus infectious bronchitis virus E can physically interact, via a putative peripheral domain, with M. Deletion of this domain resulted in a drastic reduction in the incorporation of M into virus-like particles. Immunofluorescent staining of cells coexpressing M and E supports that E interacts with M and relocates M to the same subcellular compartments that E resides in. E was retained in the pre-Golgi membranes, prior to being translocated to the Golgi apparatus and the secretory vesicles; M was observed to exhibit similar localization and translocation profiles as E when coexpressed with E. Deletion studies identified the C-terminal 6-residue RDKLYS as the endoplasmic reticulum retention signal of E, and site-directed mutagenesis of the -4 lysine residue to glutamine resulted in the accumulation of E in the Golgi apparatus. The third domain of E that plays a crucial role in virus budding is a putative transmembrane domain present at the N-terminal region, because deletion of the domain resulted in a free distribution of the mutant protein and in dysfunctional viral assembly.

Low-bit-rate video coding using dense motion field and uncovered background prediction

It is well known that accurate dense motion field can improve the video coding efficiency. This paper presents a novel Markov random field (MRF) model that estimates both the dense motion and uncovered background fields in image sequences, and the application of these estimates in H.263-based video coding framework.

Identification of a novel cleavage activity of the first papain-like proteinase domain encoded by open reading frame 1a of the coronavirus Avian infectious bronchitis virus and characterization of the cleavage products

The coronavirus Avian infectious bronchitis virus (IBV) employs polyprotein processing as a strategy to express its gene products. Previously we identified the first cleavage event as proteolysis at the Gly(673)-Gly(674) dipeptide bond mediated by the first papain-like proteinase domain (PLPD-1) to release an 87-kDa mature protein. In this report, we demonstrate a novel cleavage activity of PLPD-1. Expression, deletion, and mutagenesis studies showed that the product encoded between nucleotides 2548 and 8865 was further cleaved by PLPD-1 at the Gly(2265)-Gly(2266) dipeptide bond to release an N-terminal 195-kDa and a C-terminal 41-kDa cleavage product. Characterization of the cleavage activity revealed that the proteinase is active on this scissile bond when expressed in vitro in rabbit reticulocyte lysates and can act on the same substrate in trans when expressed in intact cells. Both the N- and C-terminal cleavage products were detected in virus-infected cells and were found to be physically associated. Glycosidase digestion and site-directed mutagenesis studies of the 41-kDa protein demonstrated that it is modified by N-linked glycosylation at the Asn(2313) residue encoded by nucleotides 7465 to 7467. By using a region-specific antiserum raised against the IBV sequence encoded by nucleotides 8865 to 9786, we also demonstrated that a 33-kDa protein, representing the 3C-like proteinase (3CLP), was specifically immunoprecipitated from the virus-infected cells. Site-directed mutagenesis and expression studies showed that a previously predicted cleavage site (Q(2583)-G(2584)) located within the 41-kDa protein-encoding region was not utilized by 3CLP, supporting the conclusion that the 41-kDa protein is a mature viral product.

Long-term outcome and disease control in near-fatal asthma

Patients who have survived an episode of intubation and mechanical ventilation for acute respiratory failure due to a severe and unresponsive asthmatic attack are considered to have experienced a near-fatal asthma (NFA) attack. Such patients are at a higher risk of similar severe attacks and hence of death in the future. The aims of the study were to: (i) evaluate the outcome; (ii) identify any persistent deficiencies in asthma management, and (iii) assess self-management knowledge in survivors of NFA. Ninety-three consecutive patients who had been treated for NFA in the Intensive Care Unit of an urban teaching hospital in Singapore from 1992 to 1997 were studied. All hospital records were reviewed retrospectively. Survivors were then invited to attend a questionnaire interview and to have lung function tests performed. Of the original cohort (OC) of 93 patients with NFA (mean age 55.2 years), 18 (19% OC) patients (mean age 64 years) had died while in hospital and 75 (81% OC) patients survived the initial episode of NFA and were discharged home (DH). The long-term outcome of this DH group was: 13 patients had died (17% DH) and 62 (83% DH) survived. Of these survivors, 35 were interviewed while 27 declined or were not contactable. This interview yielded the following information: (i) Hospitalisation in the past year: 66% had no hospital admission; of the 31.4% who had 2 or more admissions, most had a further NFA attack. (ii) Health care: The majority of patients (71.4%) were monitored by a single doctor. (iii) Patient knowledge of disease management was deemed good to fair for trigger avoidance (77%), for appropriate drug usage (97%). (iv) Satisfactory inhaler skill (80%). NFA is associated with a high intrahospital and long-term mortality. Although most survivors of NFA appeared to have satisfactory care and a fair understanding of medication usage, a significant minority continue to pose much morbidity and risk for death.

Regulation of mRNA 1 expression by the 5'-untranslated region (5'-UTR) of the coronavirus infectious bronchitis virus (IBV)

In this report, we show that expression of the coronavirus IBV mRNA1 is regulated by its 5'-UTR. Evidence presented demonstrates that the IBV sequence from nucleotide 1 to 1904 directs very inefficient synthesis of a product of approximately 43 kDa. Deletion of either the first 362 bp or the whole part of the 5'-UTR, however, dramatically increased the expression of the 43 kDa protein species. The mechanisms involved were investigated by two different approaches. Firstly, translation of the same construct in the presence of [3H]-leucine ruled out the possibility that initiation of small reading frames from non-AUG codons located in the 5'-UTR may compete with the authentic AUG initiation codon, and therefore inhibit the expression of ORF 1a. Secondly, expression and deletion analyses of a dicistronic construct showed that translation of the 43 kDa protein was initiated by ribosome internal entry mechanism. These studies suggest that a 'weak' ribosome internal entry signal is located in the 5'-UTR and is involved in the regulation of mRNA1 expression.

Characterisation of a papain-like proteinase domain encoded by ORF1a of the coronavirus IBV and determination of the C-terminal cleavage site of an 87 kDa protein

Our previous studies have shown that two overlapping papain-like proteinase domains (PLPDs) encoded by the IBV sequence from nucleotides 4155 to 5550 is responsible for cleavage of the ORF 1a polyprotein to an 87 kDa protein. In this study, we demonstrate that only the more 5' one of the two domains, PLPD-1 encoded between nucleotides 4155 and 5031, is required for processing to the 87 kDa protein. Site-directed mutagenesis studies have shown that the Cys1274 and His1435 residues are essential for the PLPD-1 activity, suggesting that they may be the components of the catalytic centre of this proteinase. Coexpression and immunoprecipitation studies have further revealed that PLPD can interact with the 87 kDa protein. Meanwhile, data obtained from the construction and expression of a series of deletion mutants have indicated that the 87 kDa protein is encoded by the 5'-most 2600 bp part of ORF1a. further deletion and mutagenesis studies are underway to determine precisely the C-terminal cleavage site of the 87 kDa protein.

Characterization of the two overlapping papain-like proteinase domains encoded in gene 1 of the coronavirus infectious bronchitis virus and determination of the C-terminal cleavage site of an 87-kDa protein

In a previous report, we showed that proteolytic processing of an 87-kDa mature viral protein from the coronavirus infectious bronchitis virus (IBV) 1a and 1a/1b polyproteins was mediated by two putative overlapping papain-like proteinase domains (PLPDs) encoded within the region from nucleotides 4243 to 5553 of ORF 1a (Liu et al., 1995). In this study, we demonstrate that only the first domain, PLPD-1, is responsible for this cleavage, as deletion of the second domain did not affect the formation of the 87-kDa protein. Site-directed mutagenesis studies further showed that a previously predicted nucleophilic cysteine residue (Cys1274) and a histidine residue (His1437) were essential for the proteinase activity, indicating that they may be important components of the catalytic center of the proteinase. Meanwhile, expression of a series of deletion mutants revealed that the 87-kDa protein was encoded by the 5'-most 2.6 kb of ORF 1a. Deletion and amino acid substitution mutation studies demonstrated that the Gly673-Gly674 dipeptide bond was most likely the cleavage site responsible for releasing the C-terminus of the 87-kDa protein from the 1a and 1a/1b polyproteins.

Differences in the hydrolysis of lactose and other substrates by beta-D-galactosidase from Kluyveromyces lactis

The hydrolysis of o-nitrophenyl galactopyranoside and lactose by beta-D-galactosidase from Kluyveromyces lactis was enhanced by the addition of Mg2+ and Mn2+, but the rates of activation by each metal on both substrates were not the same. The Co2+, Zn2+, and Ni2+ activated the o-nitrophenyl galactopyranoside-hydrolyzing activity of the enzyme, but these same metals inhibited the lactose-hydrolyzing activity. The addition of Mg2+ and EDTA to the assay buffer increased the hydrolysis of o-nitrophenyl galactopyranoside and lactose at different rates. The responses of o-nitrophenyl galactopyranoside and lactose to the enzyme activity were different as a function of pH. The hydrolyzing activity toward both substrates also was influenced by the concentration of the phosphate in the assay buffer. However, the profile of the enzyme activity toward each substrate was different as a function of concentration. Because the assay of beta-galactosidase using o-nitrophenyl galactopyranoside is fast and convenient, the estimation of lactose-hydrolyzing activity of the enzyme has frequently been made based on the assay of o-nitrophenyl galactopyranoside hydrolysis. As shown in this study, a slight change in the conditions of the assay system and the enzyme application may cause changes in the ability of the enzyme to hydrolyze both lactose and o-nitrophenyl galactopyranoside. The change in o-nitrophenyl galactopyranoside-hydrolyzing activity is not always consistent with that of the lactose-hydrolyzing activity under the given condition, which may cause an inaccurate estimation of the enzyme activity in the enzyme preparation as well as in actual applications of the enzyme.

Amplification and sequencing of varicella-zoster virus (VZV) gene 4: point mutation in a VZV strain causing chickenpox during pregnancy

The varicella-zoster virus (VZV) causes chickenpox (varicella) as the primary disease and shingles (zoster) as a recurrent manifestation of infection, both being generally benign and self-limiting. While these infections may be severe in adults and even life-threatening in immunosuppressed individuals, they may be amenable to effective antiviral drugs or varicella-zoster immune globulin, provided the treatment is administered early. The prompt diagnosis of VZV infections may be accelerated by rapid, sensitive and specific molecular techniques such as amplification by polymerase chain reaction (PCR) compared with slower and more cumbersome tissue culture and serological procedures. Based on the VZV gene 4 which encodes a transcriptional activator, primers were designed for use in PCR to amplify a target fragment of 381 bp. Distinct diagnostic bands were observed by agarose gel electrophoresis of PCR products of VZV strains isolated from 11 varicella and 7 zoster patients in Singapore, as well as of the Japanese vaccine Oka strain. The detection sensitivity of this PCR assay was determined to be 1 pg of purified VZV DNA equivalent to about 7,000 viral DNA copies. No target bands were amplified from negative control templates from five related human herpes-viruses and from human DNA. The specificity of the PCR products was ensured by direct cycle DNA sequencing, which revealed complete identity of the 18 VZV isolates with the published European Dumas strain. The strong sequence conservation of the target fragment renders this PCR assay highly reliable for detecting the VZV sequence. Only one VZV strain isolated from a patient with varicella during pregnancy exhibited a GGA to GAA point mutation at codon 46 of gene 4, culminating in the non-conservative substitution of Ser with Phe. The predicted secondary structure of the mutant polypeptide portrayed a radical alteration, which may influence its function in transcriptional activation.

Low frequency of endoscopic esophagitis in Asian patients

The aim of this study was to determine the frequency of endoscopic esophagitis in patients seen for upper gastrointestinal complaints in an Asian center. We studied a consecutive series of 11,943 patients undergoing diagnostic esophagogastroduodenoscopy at our unit over a 10-year period. Three hundred and eighty-nine patients (3.3%) had endoscopic esophagitis with no other significant lesion (primary esophagitis), whereas 143 (1.2%) had esophagitis associated with peptic ulcer or gastric or duodenal malignancy (secondary esophagitis). In contrast, peptic ulcer was diagnosed in 2,787 patients (23.3%) and gastric carcinoma in 286 (2.4%). The reported frequency of endoscopic esophagitis among patients undergoing endoscopy in Western countries varied from 9 to 23%. Our data therefore show that endoscopic esophagitis is much less common in Singaporean patients.

The influence of dialect group on peptic ulcer frequency amongst the Chinese in Singapore

In Singapore, peptic ulcer is more common amongst Chinese than amongst Malays or Indians. Earlier work has suggested that, amongst female Chinese, Cantonese women are more susceptible to ulcer disease when compared to females of other dialect groups. The aim of the present study was to confirm or refute this possibility. The dialect group distribution of 897 Chinese patients with peptic ulcer (duodenal ulcer 601, gastric ulcer 296) was compared with that of non-ulcer dyspepsia patients and 1602 general medical patients attending the same medical units. The proportion of various dialect groups (including Cantonese) was similar in all patient groups. The proportion of ulcer patients presenting with haemorrhage was also similar in the different dialect groups. We conclude that no major dialect differences exist in peptic ulcer frequency amongst the Chinese in Singapore.