3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item A comparison of the radiological features of lung cancer in HIV-infected and HIV-uninfected individuals in a South African hospital(2018) Nel, AndrewINTRODUCTION: Lung Cancer (LC) is one of the most important causes of death worldwide. With the increase in non-AIDS defining cancers, like LC, this is concerning in South Africa, with the country’s high incidence of HIV. AIM: To correlate the CT features of LC with the histological / cytological diagnoses and compare these findings in HIV-infected and HIV-uninfected patients. METHOD: 54 patients with lung lesions on CT, who had image-guided, biopsy-proven malignancies were retrospectively reviewed. RESULTS: The study population had a M:F ratio of 31:23, with 31.5% HIV-infected and a mean age of 59 years (SD±11). 85% had constitutional symptoms of LC and 59% had a smoking history. The most prevalent subtypes were squamous cell carcinoma (37%), adenocarcinoma (24.1%) and large cell carcinoma (24.1%). CT features were a mean axial lesion size anteroposterior of 67mm and transverse of 70mm, with an upper lobe predominance (76%). Other features were an irregular (70.4%), lobulated (55.6%) margin with pleural tags (61.1%) and spiculation (51.9%). Associated findings were CT significant mediastinal lymphadenopathy (77.8%), involvement of vessels or bronchi (68.5%), convergence of surrounding structures (64.8%), pleural effusion (55.6%) and secondary pulmonary lesions (51.9%). The HIV-infected patients had a mean age of 51 (SD±11) years iv and a strong Tuberculosis history (60%). There was no statistical difference in the imaging features between the HIV-infected and HIV-uninfected patients. CONCLUSION: HIV-infected patients with LC present younger. Larger studies are needed to confirm whether this subgroup has more atypical lesions and need a different set of criteria for CT evaluation.Item The identification of cell-cycle related genes in response to antiretroviral drug treatment (ART) in lung cancer(2017) Marima, Rahaba MakgotsoSouth Africa has the largest ARV treatment programme in the world, wherein highly active antiretroviral treatment (HAART) has improved the health related quality of life (HRQoL) in HIV/AIDS patients. On the contrary, cancers not previously associated with HIV/AIDS (non-Aids defining cancers; NADCs) have been shown to be increasing, compared to the AIDS defining cancers (ADCs). Lung cancer, as a NADC has been documented in the HIV/AIDS population as a leading malignancy. The poor understanding of the association between ARV drugs and lung cancer places a burden on public health, both globally and in South Africa (SA). Furthermore, the deregulation of the cell-cycle is one of the hallmarks of cancer, including lung cancer. The main aim of this study was to elucidate the effects of HAART components Efavirenz (EFV) and Lopinavir/ritonavir (LPV/r) on cell-cycle related genes in an in vitro lung cancer model. To achieve this, cellular based, molecular and Bio-Informatics approaches were employed. First, the cytotoxic effects of EFV (at 4, 13, 26, 50 μM) and LPV/r (at 10, 32, 50, 80 μM), for 24h, 48h and 72h on normal lung fibroblasts (MRC-5) and lung adenocarcinoma (A549) cells, were evaluated using the Alamar Blue (AB) assay. This was then followed by cell-impedance “xCELLigence” real-time cell analysis (RTCA) assay. This was done to determine the effects of EFV (at 4, 13, 50 μM) and LPV/r (at 10, 32, 80 μM) on cell viability, cell death and proliferation. Cell-cycle analysis using propidium iodide (PI) by Fluorescence-activated cell sorting (FACS) was done to quantify DNA present at each of the cell-cycle stages of the cell-cycle in response to ARV treatment. Subsequently, an apoptosis assay using Annexin V FITC and Propidium iodide (PI) dual staining by FACS was carried out to confirm and quantify the ARVs potential apoptotic effects. Then, 4′,6-diamidino-2-phenylindole (DAPI) staining was used to assess changes in nuclear morphology exerted by the ARVs’ effects. A more in depth interrogation of the cell-cycle was performed using a focussed gene array panel of some 84 human cell-cycle related genes. First, total RNA was isolated from both treated and untreated MRC-5 and A549 cells and reverse transcribed to cDNA for use as template in the PCR array reactions. From the array gene expression results, by convention a ±2 fold up-or-down-regulation was used as the basis of target selection. Following this, a real-time quantitative PCR (RT-qPCR) validation of selected genes of interest was done to quantify and confirm the PCR array results. This was followed by in-silico Bio-informatics analysis to map the molecular pathways regulated by the identified targets. For this purpose, STRING, Database for Annotation, Visualization and Integrated Discovery (DAVID), Reactome and Ingenuity Pathway Analysis (IPA) databases were used. Interestingly, double-edged oncogenic properties of both EFV and LPV/r at different concentrations were identified. The proliferative effects of EFV at 4, 13μM and LPV/r at10 μM, were elucidated, while 26, 50μM of EFV, and 32μM of LPV/r had slight inhibitory effects on cell proliferation. LPV/r at concentrations of 50 and 80μM exerted cytotoxic effects on the cells, as demonstrated by the AB and xCELLigence RTCA assays. Cell-cycle analysis using PI staining, particularly showed cell-cycle arrest at 32μM LPV/r, and a shift to G2/M by 13μM EFV, plasma relevant doses, compared to the untreated cells. An increasing apoptosis percentage was observed with increasing LPV/r concentrations, that is, 80μM LPV/r raised the apoptosis percentage almost two-fold compared to 32μM. This was coupled by necrosis, observed in a time-dependant manner. DAPI staining confirmed loss of nuclear integrity post ARV exposure, suggesting that both EFV and LPV/r impose damage to the genomic DNA. To further assess the observed changes in nuclear morphology, the effects of EFV and LPV/r on the expression of an arrayed panel of human cell-cycle genes in cancer and normal lung cells was determined. Significantly differentially expressed targets were identified and further quantified and confirmed by RT-qPCR. Such targets included ATM, p53, cyclin-dependant kinase inhibitors (CDKIs), such as, p21, aurora kinase B (AURKB), Mitotic Arrest Deficient-Like 2 (MAD2L2) and the apoptosis related gene, caspase 3 (CASP3). Bio-Informatics analyses revealed close and direct protein-protein interactions (PPIs) between these targets, notably, with change in interaction between the gene products involved in DNA repair mechanisms, observed between ARV treated and untreated groups, as illustrated by STRING interactions. DAVID, Reactome and IPA analysis showed changes in expression of genes related to stress and toxicity and DNA damage response genes. In particular, ATM, p53 and its downstream targets such as GADD45A (growth arrest and DNA damage inducible alpha) gene were up-regulated by ARV treatment, while cyclin/CDK activity was down-regulated, resulting in reduced cell proliferation. Thus in summary, both EFV and LPV/r altered the expression levels of cell-cycle related genes, influencing overall cellular health, acting to either inhibit or stimulate cell proliferation. This suggests EFV’s and LPV/r’s proliferative and inhibitory roles in the proliferation of lung cells. Moreover, future directions can include the transfection of lung cells with HIV provirus followed by treatment of the cells with the same ARVs under study. This could be substantiated by including HIV positive patient samples on and off ARV drug treatment with lung cancer, including HIV negative patients with cancer as one of the controls.Item EGFR mutations in non small cell lung cancer patients in South Africa(2015-04-17) Chan, Sze WaiIntroduction: Tyrosine kinase inhibitors and EGFR mutations has changed the treatment approach to lung cancer globally. This retrospective study will look at factors associated with EGFR mutations and define the EGFR mutation rate in South Africa. Methods: Retrospective record review from NSCLC patients in South Africa who were tested for EGFR mutations at Lancet Laboratories during 1st September 2009 to 30th June 2012. Chi-squared test was used to determine association with categorical variables. Kaplan- Meier survival analysis was done for OS and PFS between EGFR mutation positive and negative patients. Cox proportional hazards were used for subgroup analysis. Treatment practices and response were described. Results: 170 lung cancer samples were evaluable for EGFR mutation and 37 were EGFR mutation positive (21.8%). There were 22 (59.5%) exon 19 deletions, 11 (29.7%) L858R mutations, two G719X mutations, one S768I mutation and one exon 20 insertion. The median age was 63 (range 27-85). There were more females (55.6%) than males (44.4%) sent for mutation testing. Most patients were whites (71%), followed by blacks (18.3%), and other race (10.7%). 85% of all NSCLC samples tested were adenocarcinoma. None of the squamous cell carcinoma tested was positive for EGFR mutation. Smoking status was inversely proportional to EGFR mutation status (p<0.001). Over 60% patients received chemotherapy first and second line and responses decreased with each line of chemotherapy. Median PFS and OS were not different between the EGFR mutation positive and negative groups (6.85 versus 6.8 months; HR 1.6; 95% CI 0.70-3.65; p=0.2543 and 11.5 versus 12.9 months; HR 0.70; 95% CI 0.28-1.75; p=0.44, respectively). On multivariate analysis, only non-white race was associated with decrease in OS (HR 6.66; 95% CI 2.31-19.19; p=0.0004). Conclusion: EGFR mutation rate in South African lung cancer patients was 21.8%. 89% of all EGFR mutations were either exon 19 deletions or L858R point mutations. Most EGFR mutations were associated with adenocarcinoma of the lung in non-smokers. These findings were consistent with current literature in western countries. Treatment practice remained chemotherapy based, with few patients receiving EGFR TKIs. Efforts should be made to prioritized targeted treatment approach in lung cancer in South Africa.Item The relationship of zinc and copper with stage in non-small cell cancer of the lung(2011-11-23) Chetty, Dinoshan NamasivayanObjective Several studies have shown that serum copper concentrations are higher in various carcinomas when compared to a healthy population; owing to their role as an inflammatory marker. Zinc acts as a cellular growth protector and it has been demonstrated that its deficiency is involved in several stages of malignant cell transformation. However, the usefulness of the serum zinc and copper determinations in cancer prevention, detection, treatment monitoring and prognosis require further investigation. The aim of this study is to demonstrate the diagnostic and prognostic significance of serum zinc levels (SZL) and serum copper levels (SCL), and the copper/zinc (Cu/Zn) ratio, in non-small cell lung cancer (NSCLC). Materials and Methods Thirty-four patients with NSCLC were prospectively identified, prior to treatment, over a period of one calendar year (February 2003 - January 2004) at the Department of Radiation Oncology, Johannesburg General Hospital (now Charlotte Maxeke Johannesburg Academic Hospital) and the University of the Witwatersrand. SCL and SZL were measured using atomic absorption spectroscopy (AAS) and the Cu/Zn ratio was calculated. Results SCL shows an increase (mean SCL were 0.66mg/L, 0.74mg/L and 0.76mg/L for stage II, III and IV respectively) (P=0.0897); and SZL shows a decrease (0.70mg/L,0.63mg/L and 0.62mg/L for stage II, III and IV respectively) (P=0.199) with advancing stage. The levels of both these trace elements are much lower than the reference range for a normal population. The Cu/Zn ratio increases with stage (0.995, 1.308 and 1.441 for stage II, III and IV respectively). The results were not statistically significant, but a definite trend could be observed. In addition, marked differences were noted between early stages (II) and advanced stages (III and IV) of the disease. Conclusion The lower levels of both trace elements, when compared to a reference range, are an indication of the low levels of immunity and poor general condition of patients with NSCLC (with particular reference to the author‟s institution). A clear trend could be demonstrated of increasing SCLs and decreasing SZLs with progressive stages in NSCLC. The Cu/Zn ratio also reflects similar findings in relation to stages of the disease. The results were not statistically significant, although this can be attributed to a small sample size. While trace element levels and the Cu/Zn ratio cannot be advocated as a tumour marker and prognostic variable for NSCLC at present, they do merit further study, especially in a resource constrained environment, as a simple and inexpensive diagnostic and prognostic test.