CYP2D6 genetic polymorphisms and phenotypes in different ethnicities of Malaysian breast cancer patients

The cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6) is an enzyme that is predominantly involved in the metabolism of tamoxifen. Genetic polymorphisms of the CYP2D6 gene may contribute to inter-individual variability in tamoxifen metabolism, which leads to the differences in clinical response to tamoxifen among breast cancer patients. In Malaysia, the knowledge on CYP2D6 genetic polymorphisms as well as metabolizer status in Malaysian breast cancer patients remains unknown. Hence, this study aimed to comprehensively identify CYP2D6 genetic polymorphisms among 80 Malaysian breast cancer patients. The genetic polymorphisms of all the 9 exons of CYP2D6 gene were identified using high-resolution melting analysis and confirmed by DNA sequencing. Seven CYP2D6 alleles consisting of CYP2D6*1, CYP2D6*2, CYP2D6*4, CYP2D6*10, CYP2D6*39, CYP2D6*49, and CYP2D6*75 were identified in this study. Among these alleles, CYP2D6*10 is the most common allele in both Malaysian Malay (54.8%) and Chinese (71.4%) breast cancer patients, whereas CYP2D6*4 in Malaysian Indian (28.6%) breast cancer patients. In relation to CYP2D6 genotype, CYP2D6*10/*10 is more frequently observed in both Malaysian Malay (28.9%) and Chinese (57.1%) breast cancer patients, whereas CYP2D6*4/*10 is more frequently observed in Malaysian Indian (42.8%) breast cancer patients. In terms of CYP2D6 phenotype, 61.5% of Malaysian Malay breast cancer patients are predicted as extensive metabolizers in which they are most likely to respond well to tamoxifen therapy. However, 57.1% of Chinese as well as Indian breast cancer patients are predicted as intermediate metabolizers and they are less likely to gain optimal benefit from the tamoxifen therapy. This is the first report of CYP2D6 genetic polymorphisms and phenotypes in Malaysian breast cancer patients for different ethnicities. These data may aid clinicians in selecting an optimal drug therapy for Malaysian breast cancer patients, hence improve the clinical outcome of the patients

Overexpression of CTAG1B is a potential biomarker in bladder cancer

Urothelial cell carcinoma (UCC) is the most common form of bladder cancer and is associated with the need for life-long surveillance once a patient is diagnosed with a non-invasive disease. Due to the long-term risk of recurrence and the need for life-long routine monitoring and therapy, the cost per UCC patient from diagnosis to death is the highest of all cancers. The development of non-invasive biomarkers of recurrence and progression can increase survival, decrease treatment costs and improve patient quality of life. However, to date, no biomarker(s) have been endorsed for the use in the clinical management of UCC, especially in predicting risk of progression and recurrence. CTAG1B was previously found to be highly expressed in high-stage and grade bladder cancer, albeit in Caucasian cohorts. However, despite its potential as a target for cancer immunotherapy, the effect of expression modulation on cellular phenotypes has never been reported. In this study, we overexpressed CTAG1B in an invasive bladder cancer cell line, EJ28 after we confirmed that this cell line minimally expressed CTAG1B. The cells were transfected with CTAG1B-pcDNA3.1(-) and the level of expression was confirmed by qRT-PCR. Once the expression was confirmed to persist up to 72h post-transfection, the transfected cells were subjected to various phenotypic assays. In addition, the pattern of CTAG1B expression in a cohort of Malaysian bladder cancer paraffin-embedded tissues was also determined using immunohistochemistry. The effect of CTAG1B overexpression on the cell cycle, migratory and proliferative potential was observed. The changes in phenotype were compared with that of untransfected and mock controls. CTAG1B was overexpressed 20 times as compared to the untransfected and mock controls in the transfected cells. CTAG1B overexpression resulted in cells to migrate slower at 24h post-transfection but proliferate significantly faster after 72-96h post-transfection. In addition, CTAG1B was more frequently expressed in advanced bladder cancer stages and grades. The findings from this study contribute to the current knowledge of CTAG1B‟s role in tumourigenesis. Further functional studies will contribute towards realising the potential of CTAG1B as a biomarker for predicting the risk of progression and recurrence of bladder cancer

Identification and characterisation of single nucleotide polymorphisms in cytochrome P450 2D6 gene in Malaysian breast cancer patients

Worldwide as well as Malaysia, breast cancer remains the most common type of malignancy and also the major cause of cancer related deaths among women. Tamoxifen is extensively used as adjuvant hormonal therapy for estrogen receptor-positive breast cancer patients to reduce risk of recurrence and mortality. However, variability in response to tamoxifen is observed among breast cancer patients. This may be due to genetic polymorphisms of cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6) gene that influence the CYP2D6 enzyme activity in tamoxifen metabolism. To date, no study has been conducted to investigate single nucleotide polymorphism (SNP) profiles of CYP2D6 gene specific to Malaysian breast cancer patients. Hence, this study aimed to identify SNPs in the coding regions of the CYP2D6 gene in Malaysian breast cancer patients and also to predict the functional effects of the identified non-synonymous SNPs.The identification of SNPs was successfully achieved through utilisation of high resolution melting (HRM) analysis and confirmatory DNA sequencing. A total of 51 SNPs of the CYP2D6 gene consisting of 40 known SNPs and 11 novel SNPs were identified in this study. Complete genotype concordance was observed in both tumour DNA (carcinoma tissues) and germline DNA (adjacent normal tissues and blood) of 16 breast cancer patients for all the 51 SNPs. Results from logistic regression analysis showed that metastasis status, hormonal receptors status, ethnicity and SNP c.100C>T are the predictors that contribute significantly in predicting survival of breast cancer patients. Apart from that, nine out of 24 non-synonymous SNPs consisting of c.100C>T, c.271C>A, c.545T>C, c.800C>G, c.1316G>A, c.1318C>T, c.1322G>A, c.1405C>G and c.1444G>A are predicted to be deleterious SNPs by in silico analysis using bioinformatics software. CYP2D6*10/*10 was found to be the most prevalent genotype in both Malay and Chinese breast cancer patients with genotype frequency of 28.9% and 57.1%, respectively. On the contrary, Indian breast cancer patients had a high prevalence of CYP2D6*4/*10 genotype with genotype frequency of 42.8%. It has been suggested by previous studies that CYP2D6 phenotypes determined based on CYP2D6 genotypes can be used for predicting the efficacy of tamoxifen. In relation to CYP2D6 phenotype, 61.5% of Malay patients were shown to have genotypes that categorised them as extensive metabolisers, hence, it is expected that the majority of them would benefit from tamoxifen therapy. On the contrary, 57.1% of Chinese as well as Indian patients were categorised as intermediate metabolisers, which suggest that they might experience reduced efficacy of tamoxifen therapy due to the reduction of CYP2D6 enzyme activity towards tamoxifen metabolism. This indicates that future clinical CYP2D6 genotyping may need to be considered prior to the selection of hormonal therapy for breast cancer patients. In conclusion, this study represents the first effort to identify CYP2D6 SNP profiles specific to Malaysian breast cancer patients. Additionally, this study also provides information on metaboliser status of the patients, which may potentially aid clinicians towards better treatment management of breast cancer in the future

Homeobox Gene Expression Dysregulation as Potential Diagnostic and Prognostic Biomarkers in Bladder Cancer

Homeobox genes serve as master regulatory transcription factors that regulate gene expression during embryogenesis. A homeobox gene may have either tumor-promoting or tumor-suppressive properties depending on the specific organ or cell lineage where it is expressed. The dysregulation of homeobox genes has been reported in various human cancers, including bladder cancer. The dysregulated expression of homeobox genes has been associated with bladder cancer clinical outcomes. Although bladder cancer has high risk of tumor recurrence and progression, it is highly challenging for clinicians to accurately predict the risk of tumor recurrence and progression at the initial point of diagnosis. Cystoscopy is the routine surveillance method used to detect tumor recurrence. However, the procedure causes significant discomfort and pain that results in poor surveillance follow-up amongst patients. Therefore, the development of reliable non-invasive biomarkers for the early detection and monitoring of bladder cancer is crucial. This review provides a comprehensive overview of the diagnostic and prognostic potential of homeobox gene expression dysregulation in bladder cancer

Differential Protein Expression Patterns of HOXA13 and HOXB13 Are Associated with Bladder Cancer Progression

Bladder cancer is a common urological cancer and has the highest recurrence rate of any cancer. The aim of our study was to profile and characterize the protein expression of homeobox A13 (HOXA13) and homeobox B13 (HOXB13) genes in Malaysian bladder cancer patients. The protein expression of HOXA13 and HOXB13 in formalin-fixed paraffin-embedded (FFPE) bladder cancer tissues was determined by immunohistochemistry (IHC) analysis. The association between HOXA13/HOXB13 protein expression and demographic/clinicopathological characteristics of the bladder cancer patients was determined by chi-square analysis. Approximately 63.6% of the bladder cancer tissues harbored high HOXA13 expression. High HOXA13 expression was significantly associated with non-muscle invasive bladder cancer, lower tumor grade, higher number of lymph node metastases, and recurrence risk. In contrast, low HOXB13 expression (including those with negative expression) was observed in 71.6% of the bladder cancer tissues analyzed. Low HOXB13 expression was significantly associated with muscle-invasive bladder cancer, higher tumor stage, tumor grade, and metastatic risk. Both HOXA13 and HOXB13 protein expression were found to be associated with bladder tumorigenesis. The putative oncogenic and tumor suppressive roles of HOXA13 and HOXB13, respectively, suggest their potential utility as biomarkers in bladder cancer