**Detection of Superoxide Alterations Induced by 5-Fluorouracil on HeLa Cells with a Cell-Based Biosensor**

#### **Sophia Mavrikou 1,\*, Vasileios Tsekouras 1, Maria-Argyro Karageorgou 2,3, Georgia Moschopoulou 1 and Spyridon Kintzios 1,\***


Received: 9 September 2019; Accepted: 13 October 2019; Published: 16 October 2019

**Abstract:** Background: In vitro cell culture monitoring can be used as an indicator of cellular oxidative stress for the assessment of di fferent chemotherapy agents. Methods: A cell-based bioelectric biosensor was used to detect alterations in superoxide levels in the culture medium of HeLa cervical cancer cells after treatment with the chemotherapeutic agen<sup>t</sup> 5-fluorouracil (5-FU). The cytotoxic e ffects of 5-fluorouracil on HeLa cells were assessed by the MTT proliferation assay, whereas oxidative damage and induction of apoptosis were measured fluorometrically by the mitochondria-targeted MitoSOX ™ Red and caspase-3 activation assays, respectively. Results: The results of this study indicate that 5-FU di fferentially a ffects superoxide production and caspase-3 activation when applied in cytotoxic concentrations against HeLa cells, while superoxide accumulation is in accordance with mitochondrial superoxide levels. Our findings sugges<sup>t</sup> that changes in superoxide concentration could be detected with the biosensor in a non-invasive and rapid manner, thus allowing a reliable estimation of oxidative damage due to cell apoptosis. Conclusions: These findings may be useful for facilitating future high throughput screening of di fferent chemotherapeutic drugs with a cytotoxic principle based on free radical production.

**Keywords:** anticancer therapeutic strategies; apoptosis; bioelectric; biosensor; 5-fluorouracil; HeLa cell line; superoxide
