Neuroblastom är en barncancer som uppstår ur det sympatiska nervsystemet och drabbar omkring 15 barn i Sverige varje år. Högriskvarianten är associerad med mycket hög dödlighet och risk för återfall, vilket tros ha att göra med att tumörernas ovanligt heterogena sammansättning tillåter resistenta subpopulationer att motstå konventionella behandlingsmetoder. Tidigare forskning har identifierat rubbade mekanismer för celldelning som ett tillvägagångssätt för tumörcellerna att överleva DNA-skador som kemoterapeutiska droger orsakar. I detta masterprojekt analyserades fem ultra-högrisk neuroblastomcellinjer i syfte att belysa deras progression genom celldelningen efter behandling med doxorubicin och/eller gemcitabin. Vidare identifierades ataxia telangesia mutated (ATM) serine/threonine kinase som ett essentiellt protein vid inhibering av celldelningen och i samband med reparation av DNA-skador, vilket bekräftades av förhöjt uttryck av fosforylerat ATM i alla fem cellinjer efter behandling med doxorubicin, gemcitabin, och/eller en kombination av båda. Återväxt av tumörcellerna efter inhibering av fosforylerat ATM i kombination med doxorubicin och gemcitabin analyserades sedan, och fördröjd återväxt noterades i en av cellinjerna efter kombinationsbehandling. Sammantaget har nya mekanismer för behandlingsresistens hos tumörceller identifierats och alternativa kombinationsbehandlingar har visat effekt på en av fem testade neuroblastomcellinjer. / Neuroblastoma is a pediatric cancer of the sympathetic nervous system that afflicts around 15 children annually in Sweden. Despite aggressive treatment, high-risk neuroblastoma is associated with a mortality of 50% and relapse rate of up to 60%, emphasizing the need for novel treatment options. In this study, fluoresce activated cell sorting was used to analyze cell cycle progression in five ultra-high-risk neuroblastoma cell lines: BE(2)-C, Kelly, SK-N-AS, SK-N-DZ, and SK-N-FI, post-treatment with doxorubicin and gemcitabine. In line with previous research, doxorubicin primarily induced cell cycle arrest in G2/M-phase and gemcitabine in the S-phase. Combined, the compounds induced varied effects, with accumulation primarily in the G1-and S-phase. Immunoblotting revealed elevated levels of phosphorylated ATM (pATM), a key regulator of cell cycle arrest and DNA damage signaling, across all five cell lines post-treatment to doxorubicin, gemcitabine, and/or the combination, indicating its vital role in their survival. Kelly stood out in both cell cycle progression and ATM phosphorylation, exhibiting minimal to no changes in cell cycle accumulation or pATM expression when exposed to the combined treatment, despite reacting to both monotherapies. These results may indicate that Kelly might implement an alternative mechanism of regulation compared to the remaining cell lines. To explore targeted inhibition of pATM, we employed the ATM kinase inhibitor KU-55933, which in BE(2)-C cells reduced expression levels of pATM when combined with doxorubicin, but not gemcitabine or the combination. Regrowth assays showed increased efficacy of doxorubicin and gemcitabine upon addition of the ATM kinase inhibitor KU-55933 in one of the tested cell lines in comparison to doxorubicin alone. However, longer incubation time is needed before the effect can be fully evaluated. These findings shed light on the differential cell cycle behavior in high-risk neuroblastoma cell lines exposed to combination therapy and suggest a vital role of ATM in the DNA damage response following doxorubicin and gemcitabine treatment. Further investigations are warranted to explore alternative strategies for enhancing the effectiveness of doxorubicin and gemcitabine in the treatment of this aggressive cancer subtype.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-334207 |
| Date | January 2023 |
| Creators | Johannesson, Alexandra |
| Publisher | KTH, Proteinvetenskap |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | TRITA-CBH-GRU ; 2023:134 |
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