In an attempt to find better cancer treatments, a new mathematical model proposed by Klika & Marsik (2009) suggests that more cancer cells could possibly be killed by applying several stress factors to tumour cells, however only as a simulation in silico. The proposed stresses include healthy cell anti-tumour effect, the biochemical effect exerted by a cytotoxic drug and a newly introduced mechanical stress. The hypothesis entails that upon applying these three stress factors together simultaneously to tumour cells, the concentration of the tumour cells decreases more than if a stress factor was applied alone. The two main objectives in this study are: (1) to test the aforementioned hypothesis for the first time in vitro on HepG2 cells (human hepatocellular carcinoma cell line) and (2) to determine the mode of cancer cell death after applying the stress factors. In vitro experiments were conducted using HepG2 cells and the following stress factors were employed: (1) mechanical stress, (2) Cisplatin and (3) PBMCS (Peripheral Blood Mononuclear Cells) co-culture. The effects of the stress factors on HepG2 cells were assessed for cytotoxicity by MTT assay and the mode of cell death was examined by expression of certain apoptosis-related genes (Bax, XIAP and HSP70) on the RNA level and the cleavage of PARP-1 on the protein level. The percentage of cell survival after 24 hours exposure to the various stresses were as follows: mechanical stress alone (~55%), Cisplatin (~70%), PBMCs co-culture (~69%), mechanical stress & Cisplatin (~35%), mechanical stress & PBMCs (~45%), Cisplatin & PBMCs (~35%) and lastly mechanical stress, Cisplatin & PBMCs (~29%). RNA expression analysis of Bax revealed that most of the single stresses, double stresses and triple stresses employed Bax-dependent pathways for HepG2 cell death except PBMCs co-culture alone and PBMCs combined with mechanical stress. Concerning PARP-1, some of the stress factors caused death of HepG2 cells by apoptosis, employing PARP-1, while others did not, proposing that cells used diverse modes of death after exposure to different stress factors. In summary, the mathematical model was validated in vitro as combining two stress factors increased HepG2 cell death and further to a greater extent when combining the three stress factors together, suggesting that future studies on combined stress factors may lead to novel and more effective cancer-targeted therapy.
School of Sciences and Engineering
MS in Biotechnology
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(2021).Triple trouble: examining the effect of combining mechanical stress, PBMCs and cisplatin on hepG2 cell death [Thesis, the American University in Cairo]. AUC Knowledge Fountain.
Ziko, Lalia. Triple trouble: examining the effect of combining mechanical stress, PBMCs and cisplatin on hepG2 cell death. 2021. American University in Cairo, Thesis. AUC Knowledge Fountain.