Supervisors info:
ΣΤΡΑΒΟΠΟΔΗΣ ΔΗΜΗΤΡΙΟΣ, Αναπληρωτής Καθηγητής Βιολογίας Κυττάρου & Ανάπτυξης, Βιολογίας, ΕΚΠΑ
ΓΕΡΑΣΙΜΟΣ ΒΟΥΤΣΙΝΑΣ, ΕΡΕΥΝΗΤΗΣ Α΄, ΕΚΕΦΕ "Δημόκριτος"
ΈΜΑ ΑΝΑΣΤΑΣΙΑΔΟΥ, ΕΡΕΥΝΗΤΡΙΑ Γ΄, ΙΙΒΕΑΑ
Summary:
Oxidative phosphorylation is a mitochondrial function, which is a fundamental and at the same
time highly necessary process for the proper functioning of cells. Various chemical agents, such
as rotenone, can cause inhibition of the first complex of the electron transport chain, with the aim
of greater production of reactive oxygen species (ROS). A consequence of the above is the
reduction of mitochondrial function, due to the creation and accumulation of damage to the
genetic material and proteins of the mitochondria.
Cells, however, can recognize and respond to this mitochondrial disfunction by activating four
stress response mechanisms. This concerns the mitochondrial unfolded protein response
(MTUPR), the integrated stress response (ISR), the cytosolic heat shock response (HSR) and the
antioxidant stress response (ASR). It is all about the activation of genes, whose action concerns
the settlement of problems and the general restoration of mitochondrial proteostasis.
The aim of this specific master's thesis is to study the possible induction of the four previous
response mechanisms in the presence of misfolded protein stress, which is due to the production
of excess oxygen free radicals. The inhibition of the first complex of oxidative phosphorylation
in these organelles, took place in the cancer cell lines, fibrosarcoma (HT1080) and melanoma
(WM266-4), with the help of the chemical agent rotenone. This chemical causes significant
mitochondrial disfunction by inducing the generation of oxidative stress.
In other words, the study of the effect of rotenone focused on the gene expression at the
transcriptome level of these mitochondrial stress response mechanisms. Naturally, of course, the
cell seeks to respond to this and fight it. Otherwise, the mitochondrial damage that occurs due to
this form of cellular stress is particularly harmful to the proper functioning of the cells, while at
the same time becoming a threatening factor for their survival.
It was found that our chemical agent was able to activate all the genes of interest for the task,
which are involved in the four mechanisms (ISR, MTUPR, HSR and ASR) in both cell types. On
the contrary, the only exception was in the fibrosarcoma cell line, in which no satisfactory
transcription of the LONP-1 gene was found, a gene involved in the mitochondrial UPR
pathway. Nevertheless, the fact that the toxicity in these cells was evident should not be
underestimated.
Finally, the data that can be extracted from the present work is that rotenone is a capable
chemical agent for the activation of the following pathways, the mitochondrial UPR, the ISR, the
HSR and finally the ASR in the cancer cell lines under study (HT1080) and (WM266-4),
fibrosarcoma as well as melanoma, respectively. This fact, which indicates that rotenone is a
capable chemical, which can be used as a potential drug substance or included as a combination
together with other drug agents for cancer treatment.
Keywords:
complex I, rotenone, stress, proteostasis
