Lay-Harn Gam

Immunoaffinity extraction and tandem mass spectrometric analysis of human chorionic gonadotropin in doping analysis

A confirmatory and quantitative HPLC-tandem mass spectrometry (MS-MS) method for human chorionic gonadotropin hormone (hCG) at concentrations as low as 5 IU/l following immunoaffinity extraction of the glycoprotein from urine was developed. The extraction method involved retention of urinary hCG in the immunoaffinity column via specific antigen-antibody interaction. A variety of eluents were then used to quantitatively elute hCG from the immunoaffinity column. Qualitative and quantitative analysis of hCG were undertaken using MS-MS by identifying the amino acid sequence of the marker peptide betaT5 obtained from hCG by tryptic digestion and the peak areas of three product ions b(6)(+), b(9)(+) and y(11)(+), respectively.

Comparison of Protein Expression Profiles of Different Stages of Lymph Nodes Metastasis in Breast Cancer

Breast cancer is the most common cancer among women worldwide. Breast cancer metastasis primarily happens through lymphatic system, where the extent of lymph node metastasis is the major factor influencing staging, prognosis and therapeutic decision of the disease. We aimed to study the protein expression changes in different N (regional lymph nodes) stages of breast cancer. Protein expression profiles of breast cancerous and adjacent normal tissues were mapped by proteomics approach that comprises of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and tandem mass spectrometry (LC-MS/MS) analysis. Calreticulin and tropomyosin alpha 3 chains were the common up-regulated proteins in N0, N1 and N2 stages of breast cancer. Potential biomarker for each N stage was HSP 70 for N0, 80 k protein H precursor and PDI for N1 stage while 78 kDa glucose-regulated protein was found useful for N2 stage. In addition, significant up-regulation of PDI A3 was detected only in the metastasized breast cancer. The up-regulation expression of these proteins in cancerous tissues can potentially use as indicators for diagnosis, treatment and prognosis of different N stages of breast cancer.

The Anti-Cancer Property of Proteins Extracted from Gynura procumbens (Lour.) Merr

Gynura procumbens (Lour.) Merr. belongs to the Asteraceae Family. The plant is a well-known traditional herb in South East Asia and it is widely used to treat inflammation, kidney discomfort, high cholesterol level, diabetic, cancer and high blood pressure. Our earlier study showed the presence of valuable plant defense proteins, such as peroxidase, thaumatin-like proteins and miraculin in the leaf of G. procumbens. However, the effects of these defense proteins on cancers have never been determined previously. In the present study, we investigated the bioactivity of gel filtration fractionated proteins of G. procumbens leaf extract. The active protein fraction, SN-F11/12, was found to inhibit the growth of a breast cancer cell line, MDA-MB-231, at an EC50 value of 3.8 µg/mL. The mRNA expressions of proliferation markers, Ki67 and PCNA, were reduced significantly in the MDA-MB-23 cells treated with SN-F11/12. The expression of invasion marker, CCL2, was also found reduced in the treated MDA-MB-231 cells. All these findings highlight the anti-cancer property of SN-F11/12, therefore, the proteins in this fraction can be a potential chemotherapeutic agent for breast cancer treatment.

Proteome Analysis of Abundant Proteins Extracted from the Leaf of Gynura procumbens (Lour.) Merr

Gynura procumbens (Lour.) Merr. is a traditionally used medicinal plant to decrease cholesterol level, reduce high blood pressure, control diabetics, and for treatment of cancer. In our present study, a proteomic approach was applied to study the proteome of the plant that had never analyzed before. We have identified 92 abundantly expressed proteins from the leaves of G. procumbens (Lour.) Merr. Amongst the identified proteins was miraculin, a taste-masking agent with high commercial value. Miraculin made up ∼0.1% of the total protein extracted; the finding of miraculin gave a great commercial value to G. procumbens (Lour.) Merr. as miraculin’s natural source is limited while the production of recombinant miraculin faced challenges of not being able to exhibit the taste-masking effect as in the natural miraculin. We believe the discovery of miraculin in G. procumbens (Lour.) Merr., provides commercial feasibility of miraculin in view of the availability of G. procumbens (Lour.) Merr. that grow wildly and easily in tropical climate.

The Differential Expression of Aqueous Soluble Proteins in Breast Normal and Cancerous Tissues in Relation to Ethnicity of the Patients; Chinese, Malay and Indian

Female breast cancer is one of the leading causes of female mortality worldwide. In Malaysia, breast cancer is the most commonly diagnosed cancer in women. Of the women in Malaysia, the Chinese have the highest number of breast cancer cases, followed by the Indian and the Malay. The most common type of breast cancer is infiltrating ductal carcinoma (IDC). A proteomic approach was applied in this study to identify changes in the protein profile of cancerous tissues compared with normal tissues from 18 patients; 8 Chinese, 6 Malay and 4 Indian were analysed. Twenty-four differentially expressed hydrophilic proteins were identified. We evaluated the potential of these proteins as biomarkers for infiltrating ductal carcinoma based on their ethnic-specific expressions. Three of the upregulated proteins, calreticulin, 14-3-3 protein zeta and 14-3-3 protein eta, were found to be expressed at a significantly higher level in the cancerous breast tissues when compared with the normal tissues in cases of infiltrating ductal carcinoma. The upregulation in expression was particularly dominant in the Malay cohort.

The PCA and LDA Analysis on the Differential Expression of Proteins in Breast Cancer

Breast cancer is a leading cause of mortality in women. In Malaysia, it is the most common cancer to affect women. The most common form of breast cancer is infiltrating ductal carcinoma (IDC). A proteomic approach was undertaken to identify protein profile changes between cancerous and normal breast tissues from 18 patients. Two protein extracts; aqueous soluble and membrane associated protein extracts were studied. Thirty four differentially expressed proteins were identified. The intensities of the proteins were used as variables in PCA and reduced data of six principal components (PC) were subjected to LDA in order to evaluate the potential of these proteins as collective biomarkers for breast cancer. The protein intensities of SEC13-like 1 (isoform b) and calreticulin contributed the most to the first PC while the protein intensities of fibrinogen beta chain precursor and ATP synthase D chain contributed the most to the second PC. Transthyretin precursor and apolipoprotein A-1 precursor contributed the most to the third PC. The results of LDA indicated good classification of samples into normal and cancerous types when the first 6 PCs were used as the variables. The percentage of correct classification was 91.7% for the originally grouped tissue samples and 88.9% for cross-validated samples.

The application of pattern recognition techniques in metabolite fingerprinting of six different Phyllanthus spp.

FTIR spectroscopy was used together with multivariate analysis to distinguish six different species of Phyllanthus. Among these species P. niruri, P. debilis and P. urinaria are morphologically similar whereas P. acidus, P. emblica and P. myr- tifolius are different. The FTIR spectrometer was used to obtain the mid-infrared spectra of the dried powdered leaves in the region of 400-4000 cm −1 . The region of 400-2000 cm −1 was analyzed with four different pattern recognition methods. Ini- tially, principal component analysis (PCA) was used to reduce the spectra to six principal components and these variables were used for linear discriminant analysis (LDA). The second technique used LDA on most discriminating wavenumber variables as searched by genetic algorithm using canonical variate approach for either 30 or 60 generations. SIMCA, which consisted of constructing an enclosure for each species using separate principal component models, was the third technique. Finally, multi-layer neural network with batch mode of backpropagation learning was used to classify the samples. The best results were obtained with GA of 60 gens. When LDA was run with the six wavenumbers chosen (1151, 1578, 1134, 609, 876 and 1227), 100% of the calibration spectra and 96.3% of the validation spectra were correctly assigned.

The Differential Expression of Aqueous Soluble Proteins in Breast Normal and Cancerous Tissues in Relation to Stage and Grade of Patients

Breast cancer is a leading cause of female deaths worldwide. In Malaysia, it is the most common form of female cancer while Infiltrating ductal carcinoma (IDC) is the most common form of breast cancer. A proteomic approach was used to identify changes in the protein profile of breast cancerous and normal tissues. The patients were divided into different cohorts according to tumour stage and grade. We identified twenty-four differentially expressed hydrophilic proteins. A few proteins were found significantly related to various stages and grades of IDC, amongst which were SEC13-like 1 (isoform b), calreticulin, 14-3-3 protein zeta, and 14-3-3 protein eta. In this study, we found that by defining the expression of the proteins according to stages and grades of IDC, a significant relationship between the expression of the proteins with the stage or grade of IDC can be established, which increases the usefulness of these proteins as biomarkers for IDC.

Method development for analysis of proteins extracted from the leaves of Orthosiphon aristatus

Orthosiphon aristatus is a traditionally used medicinal plant. In order to study the proteome of the plant, we have developed a simple plant protein extraction method by direct extraction of protein using a modified 2D-gel compatible tris-sucrose buffer followed by a double TCA-acetone precipitation. This method omitted the use of toxic phenol which is widely used in the studies of plants proteins. Moreover, it shortens the lengthy extraction procedure of phenol extraction and back-extraction method and therefore reduced the extraction time (by 2h) while increased in protein yields (by 50%). Comparison of the 2D-gel images of the two extracts revealed that >60 extra protein spots were detected in the extract of our current method. The method was applied on the leaves of O. aristatus collected from six geographical areas in Malaysia. The correlation coefficient of each replicate gels from the six areas ranged from 0.70 to 0.90 indicating good reproducibility of the method.

Proteomics of Grade 3 infiltrating ductal carcinoma in Malaysian Chinese breast cancer patients

Breast cancer is the leading cause of cancer‐related mortality and morbidity among women worldwide and IDC (infiltrating ductal carcinoma) is the most common type of invasive breast cancer. The changes in the biological behaviour of cancer tissue can be predicted by measuring the differential protein expression of normal and cancerous tissues. Using a combination of SDS/PAGE and LC (liquid chromatography)–MS/MS (tandem MS), we identified 82 common and differentially expressed proteins from normal and cancerous breast tissues in 20 Malaysian Chinese patients with IDC. These proteins are extracted from the normal and cancerous tissue of patients and therefore represent the actual proteins involved in cancer development. Proteins identified possibly have significant roles in the development of breast cancer in Malaysian Chinese patients in view of their consistent expression in most of the patients, although some of the proteins had not been detected in earlier studies that were mostly carried out in Western countries. This observation suggests that molecular mechanisms leading to breast cancer development in this region may not be identical with those leading to IDC in Western regions.