Endoplasmic reticulum stress modulates therapeutic responses in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the primary types of liver cancer, and the mortality trend of HCC patients is estimated to continue rising in the future. Chemotherapy drugs or targeted therapies are considered primary treatment modalities for intermediate stage or advanced stage HCC. Although these drugs can extend the survival rate of HCC patients, prolonged treatment often raises concerns about drug resistance or cancer recurrence, leading to undesirable therapeutic outcomes. Drug treatments generally involve promoting cytotoxicity and inhibiting oncogenic signaling pathways, and the response of cancer cells to drug-induced stress situations may potentially impact the effectiveness of treatment. The unfolded protein response (UPR) acts as a cellular stress response mechanism, activating pathways such as DNA repair and autophagy to help cellular survival when cells are damaged. It has also been shown that under sustained or excessive stress, UPR can control cell fate towards programmed cell death, such as apoptosis. Previous studies have found that activation of UPR plays an essential role in cancer cell growth and drug resistance. Various molecules or signaling pathways regulated by the UPR assist cancer cells in responding to anti-cancer drugs, enabling their survival during treatment. Therefore, the present review illustrated genetic molecules or signaling pathways controlled by the UPR and investigates their influence on liver cancer drugs. Moreover, the review also summarizes the partial effects of UPR, including lipid droplet formation and inflammatory stimulation, and their roles in HCC development and drug resistance, respectively.