Cisplatin is a standard treatment for prostate cancer, which is the third leading cause of cancer-related deaths among men globally. However, patients who have undergone cisplatin can rxperience relapse. tRNA-derived fragments (tRFs) are small non-coding RNAs generated via tRNA cleavage; their physiological activities are linked to the development of human diseases. Specific tRFs, including tRF-315 derived from tRNALys, are highly expressed in prostate cancer patients. However, whether tRF-315 regulates prostate cancer cell proliferation or apoptosis is unclear. Herein, we confirmed that tRF-315 expression was higher in prostate cancer cells (LNCaP, DU145, and PC3) than in normal prostate cells. tRF-315 prevented cisplatin-induced apoptosis and alleviated cisplatin-induced mitochondrial dysfunction in LNCaP and DU145 cells. Moreover, transfection of tRF-315 inhibitor increased the expression of apoptotic pathway-related proteins in LNCaP and DU145 cells. Furthermore, tRF-315 targeted the tumor suppressor gene GADD45A, thus regulating the cell cycle, which was altered by cisplatin in LNCaP and DU145 cells. Thus, tRF-315 protects prostate cancer cells from mitochondrion-dependent apoptosis induced by cisplatin treatment.
Colon cancer is one of the most frequently diagnosed cancer types. Some colon cancer cases resist standard anticancer drugs. Therefore, many studies have focused on developing therapeutic supplements using natural products with low side effects and broad physiological activity. Eupatilin is a flavonoid that is mainly extracted from artemisia and promotes apoptosis in numerous cancer types. However, since the current understanding of its physiological mechanisms on colon cancer cells is insufficient, we investigated how eupatilin affects the growth of two colon cancer cell lines, namely HCT116 and HT29. Our results showed that eupatilin inhibits cell viability and induces apoptosis accompanied by mitochondrial depolarization. It also induces oxidative stress in colon cancer cells and regulates the expression of proteins involved in the endoplasmic reticulum stress and autophagic process. Moreover, eupatilin may target the PI3K/AKT and mitogen-activated protein kinase (MAPK) signaling pathways in colon cancer cells. It also prevents colon cancer cell invasion. Furthermore, eupatilin has a synergistic effect with 5-fluorouracil (5-FU; a standard anticancer drug) on 5-FU-resistant HCT116 cells. These results suggest that eupatilin can be developed as an adjuvant to enhance traditional anticancer drugs in colon cancer.
Fraxetin is a natural compound extracted from Fraxinus spp. and has various functions such as antibacterial, antioxidant, neuroprotective, and antifibrotic effects. Although studies have reported its anticancer properties in lung and breast cancer, little is known about colon cancer, the most frequent type of cancer. Thus, we used two colon cancer cell lines, HT29 and HCT116 cells, to investigate whether fraxetin could inhibit the capabilities acquired during tumor development. In this study, fraxetin suppressed cell viability and induced apoptotic cell death in HT29 and HCT116 cells. Furthermore, fraxetin regulated the expression of proteins involved in apoptosis in HT29 and HCT116 cells. Additionally, fraxetin induced reactive oxygen species levels and calcium influx with loss of mitochondrial membrane potential (ΔΨm) and endoplasmic reticulum stress. Moreover, fraxetin induced G2/M arrest and modulated the intracellular signaling pathway, including AKT, ERK1/2, JNK, and P38. Nevertheless, we found no cause‐effect correlation between the antiproliferative action of fraxetin and modulation of the phosphorylation state of signaling proteins. Fraxetin‐induced inhibitory effect on colon cancer cell viability was synergistic with 5‐fluorouracil (5‐FU) or irinotecan even in 5‐FU resistant‐HCT116 cells. Collectively, our results suggest that fraxetin can be effectively used as a therapeutic agent for targeting colon cancer, although it is necessary to further elucidate the relationship between the hallmark capabilities that fraxetin inhibits and the intracellular regulatory mechanism.
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