Thesis (MSc)--Stellenbosch University, 2010. / ENGLISH ABSTRACT: Oesophageal cancer (OC) is a disease characterised by development of malignant tumours in the
cell lining of the oesophagus. The disease is divided into two subtypes, which shows marked ethinic
variation, with adenocarcinoma (ADC) being more prevalent in Caucasians and squamous cell
carcinoma (SCC) more prevalent in the Black population. There are several factors that have been
associated with OC development, including oesophageal injury and inflammation, as well as excess
iron, which contributes to increased tumour growth. Investigation into OC development is essential
due to the rapidly increasing incidence rates and the poor survival rate of this complex disease.
The present study aimed to investigate nucleotide variation in the promoter region of SLC40A1, a
gene implicated in iron metabolism, in a Black South African OC population. The patient group
encompassed 80 (41 males and 39 females) unrelated patients presenting with SCC of the
oesophagus. The control group consisted of 71 unrelated, healthy population-matched control
individuals. The techniques applied for mutation detection in this study included polymerase chain
reaction (PCR) amplification, heteroduplex single stranded conformation polymorphism (HEXSSCP)
analysis, restriction fragment length polymorphism (RFLP) analysis and hybridisation probe
analysis. Identified variants were confirmed by bi-directional semi-automated DNA sequencing
analysis. Statistical analysis was performed to determine associations between identified variants
and disease incidence, as well as between identified variants and various iron parameters.
Mutation analysis of the promoter region of SLC40A1 resulted in the identification of nine
previously described (-1470C/T, -1461T/C, -1399G/A, -1355G/C, -1098G/A, -750G/A, -501T/C, -
23A/G and -8C/G) and three novel, (-1087G/C, -663C/T and -637G/A) variants as well as a
previously described trinucleotide repeat. Statistical analyses revealed statistically significant
association between -501T/C and OC in this population (P = 0.004). Statistical investigation of the
effect of the variants on iron parameters revealed various statistically significant associations.
The survival rate of OC remains poor due to absence of early symptoms and therefore late diagnosis
of the disease, after which treatment is highly ineffective. Treatment of OC would significantly
improve with earlier detection and treatment. This can be achieved by establishing a screening
programme in the populations of high risk areas, such as the Transkei area in Southern Africa.
Therefore investigation into nucleotide variation of potential modifier genes is of great importance
to improved diagnosis, treatment and counselling to individuals presenting with OC. To our
knowledge, this is the first study investigating the promoter region of SLC40A1 and possible
associations with iron dysregulation in the Black South African population with OC. / AFRIKAANSE OPSOMMING: Oesofageale kanker is ‘n siekte wat gekenmerk word deur die ontwikkeling van kwaadaardige
gewasse in the selvoering van die oesofagus. Die siekte word verdeel in twee subtipes wat
opvallende etniese variasie toon, met adenokarsinoom wat meer algemeen in die Kaukasiese
populasie voorkom en plaveisel selkarsinoom wat meer algemeen in die Swart populasie is. Daar is
verskeie faktore wat verbind word met die ontwikkeling van oesofageale kanker, insluitend
oesofageale besering en ontsteking, asook ‘n oormaat yster wat bydra tot verhoogde gewasgroei.
Ondersoek met betrekking tot die ontwikkeling van oesofageale kanker is noodsaaklik as gevolg
van die verhoogde voorkoms-tempo en die swak oorlewingsyfers van hierdie komplekse siekte.
Die huidige studie het beoog om die nukleotied variasie in die promoter area van SLC40A1, ‘n geen
betrokke in yster metabolisme, in ‘n Swart Suid-Afrikaanse oesofageale kanker populasie te
ondersoek. Die pasiënt-groep het bestaan uit 80 (41 mans en 39 vrouens) onverwante pasiënte by
wie plaveisel selkarsinoom van die oesofagus voorgekom het. Die kontrole groep het bestaan uit 71
onverwante, gesonde bevolkings-soortgelyke individue. Die tegnieke wat gebruik is vir mutasie
opsporing in hierdie studie sluit in: polimerase kettingreaksie amplifikasie, heterodupleks
enkelstring konformasie polimorfisme (HEX-SSCP) analise, restriksie fragment lengte
polimorfisme (RFLP) analise en hibridisasie peiler analise. Geïdentifiseerde variante is bevestig
deur tweerigting semi-geoutomatiseerde DNS volgorde-bepalingsanalise. Statistiese analise is
uitgevoer om moontlike assosiasies tussen geïdentifiseerde variante en siekte voorkoms, sowel as
tussen geïdentifiseerde variante en verskeie yster parameters te bepaal.
Mutasie analise van die promoter area van SLC40A1 het gelei tot die identifikasie van nege
voorheen bekende (-1470C/T, -1461T/C, -1399G/A, -1355G/C, -1098G/A, -750G/A, -501T/C, -
23A/G and -8C/G) en drie nuwe (-1087G/C, -663C/T and -637G/A) variante, sowel as ‘n bekende
trinukleotied herhaling. Statistiese analise het getoon dat daar ‘n statistiese betekenisvolle assosiasie
tussen -501T/C en oesofageale kanker in hierdie populasie voorkom (P = 0.004). Statistiese
ondersoek van die effek van die geïdentifiseerde variante op yster parameters het verskeie statisties
betekenisvolle assosiasies getoon.
Die oorlewingsyfers van oesofageale kanker bly laag as gevolg van die afwesigheid van vroeë
simptome en dus word die siekte eers op ‘n laat stadium gediagnoseer, waarna behandeling hoogs
oneffektief is. Behandeling van oesofageale kanker sou betekenisvol verbeter met vroegtydige
identifikasie en behandeling. Dit is bereikbaar deur die vestiging van ‘n siftingsprogram vir die
populasies van hoë risiko areas, soos die Transkei area in Suidelike Afrika. Ondersoeke na die
nukleotied variasie van potensiële modifiserende gene kan daarom van groot belang wees vir
verbeterde diagnose, behandeling en berading van individue met oesofageale kanker. Sover as wat
ons kennis strek, is hierdie die eerste studie wat die promoter area van die SLC40A1 geen en die
moontlike effek op yster disregulasie in ‘n Swart Suid-Afrikaanse populasie met oesofageale kanker
ondersoek.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/5470 |
| Date | 12 1900 |
| Creators | Vervalle, Jessica |
| Contributors | Zaahl, M. G., Louw, A., Warnich, L., University of Stellenbosch. Faculty of AgriSciences. Dept. of Genetics. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 150 pages : illustrations |
| Rights | Stellenbosch University |
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