Abstract
Hedyotis diffusa Willd (HDW) is a major component frequently used in Traditional Chinese Medicine for the clinical treatment of colorectal cancer (CRC) and its associated drug resistance. However, the underlying mechanism of HDW circumventing drug resistance of cancer cells remains to be elucidated. Cancer cell resistance to apoptosis and activation of the phosphatidylinositol‑3‑kinase (PI3K)/protein kinase B (AKT) signaling pathway have been implicated as major factors in the acquired resistance to chemotherapeutic anti‑cancer drugs. The present study investigated the effect and mechanisms of action of ethanol extract of Hedyotis diffusa Willd (EEHDW) on the proliferation and apoptosis of CRC 5‑fluorouracil (5‑FU) resistant (HCT‑8/5‑FU) cells. CRC HCT‑8/5‑FU cell viability following treatment with EEHDW was determined using MTT and colony formation assay. In addition, Annexin V/propidium iodide staining with flow cytometry analysis and 4',6‑diamidino‑2‑phenylindole staining were used to determine the apoptosis of drug‑resistant cancer cells following treatment with EEHDW. The mRNA and protein expression levels of B cell leukemia/lymphoma (Bcl‑2), Bcl‑2 associated X (Bax), cyclin dependent kinase 4 (CDK4), cyclin D1 and p21 were evaluated using reverse transcription‑polymerase chain reaction and western blot analysis, respectively. Furthermore, activation of the PI3K/AKT signaling pathway and expression of phosphatase and tensin homolog (PTEN), PI3K, AKT and phosphorylated (p)‑AKT were determined. EEHDW significantly reduced cell viability, inhibited cell colony formation and promoted apoptosis of HCT‑8/5‑FU cells. Furthermore, EEHDW significantly downregulated the expression of Bcl‑2, cyclin D1 and CDK4 and upregulated the expression of Bax and p21. In addition, EEHDW inhibited the activation of the PI3K/AKT pathway by increasing expression of PTEN and suppressing the expression of PI3K and p‑AKT. The present study provided the first direct evidence that EEHDW may overcome drug‑resistance in human CRC cells by inhibiting PI3K/AKT signaling pathway and provides a basis for the improved therapeutic use of HDW in the clinical treatment of cancer.