# Chemosensitizer Effects of Cisplatin- and 5-Fluorouracil-Treated Hepatocellular Carcinomas by Lidocaine

## TL;DR

Lidocaine enhances the effectiveness of chemotherapy drugs in liver cancer cells, potentially improving treatment outcomes.

## Contribution

Lidocaine is shown to act as a chemosensitizer for cisplatin and 5-FU in HCC cell lines.

## Key findings

- Lidocaine increases subG1 population and reduces reactive oxygen species in HCC cells treated with cisplatin or 5-FU.
- Lidocaine induces endoplasmic reticulum stress, apoptosis, and autophagy in HCC cells.
- Lidocaine selectively affects glutathione ratio in HepG2 but not Hep3B cells.

## Abstract

Approximately 90% of liver cancer cases are classified as hepatocellular carcinomas (HCCs), with chemotherapy and immunotherapy being the most recommended treatment options. While conventional chemotherapy specifically targets rapidly dividing cancer cells, it can also impact on healthy cells that are proliferating quickly. This collateral damage to healthy cells, along with the potential for cancer cells to develop resistance, presents significant challenges for conventional chemotherapy in liver cancer patients. Hepatic artery infusion of chemotherapy (HAIC) generally leads to reduced toxicity and fewer side effects. The process of catheter insertion is usually performed under local anesthesia, with lidocaine being the preferred choice to combine with various chemotherapeutics in HCC treatment. In our study, we explored the effects of repurposing lidocaine in combination with cisplatin or 5-fluorouracil (5-FU) on two HCC cell lines, HepG2 and Hep3B. Our cytotoxicity analysis revealed that lidocaine functions as a chemosensitizer for cisplatin and 5-FU in both HepG2 and Hep3B cells. Specifically, we observed an increase in the subG1 population and a reduction in cytosolic reactive oxygen species in cisplatin- or 5-FU-treated HepG2 and Hep3B cells. Interestingly, lidocaine selectively decreased the reduced/oxidized glutathione ratio in cisplatin- or 5-FU-treated HepG2 cells but not in Hep3B cells. Furthermore, lidocaine induced endoplasmic reticulum stress, apoptosis, mitochondrial membrane depolarization, lipid peroxidation, and autophagy while suppressing cellular proliferation HepG2 and Hep3B cells. In conclusion, our study demonstrates the synergistic potential of combining lidocaine with cisplatin or 5-FU for the treatment of HCC, indicating that lidocaine may serve as an effective chemosensitizer. These findings highlight a new clinical advantage of using repurposing lidocaine as a chemosensitizer in the current HAIC procedure, suggesting that this combination warrants further exploration through rigorous clinical trials. In the future, we can better optimize therapeutic regimens, potentially leading to improved patient outcomes in HCCs.