Novel therapeutic effects of Haprolid in Hepatocellular carcinoma

Introduction:

Hepatocellular carcinoma (HCC) represents a major health burden with limited curative treatment options. There is a pressing need for novel strategies to impact the development of inoperable HCC. Haprolid is a novel natural product isolated from the myxobacterium Byssovorax cruenta. Recent studies have reported Haprolid as a potent selective cytotoxin against several tumor cell lines including HCC cells. The aim of the present study is to assess whether Haprolid could be used to prevent HCC progression.

Methods and Materials:

We investigated the effects of Haprolid in human HCC cell lines (Huh-7, Hep 3B) and in vivo using an HCC xenograft mouse model. Cytotoxic activity of Haprolid was determined by the WST-1 assay at various concentrations ranging from 0.001 to 10 µg/mL. We also performed cell proliferation, wound healing, invasion and tumorsphere assays. Apoptosis and cell-cycle distribution were determined by annexin V, PI staining and flow cytometry. Epithelial-mesenchymal transition (EMT) markers, cell cycle and apoptotic markers and several important signaling proteins including AKT and p-AKT were tested by immunoblot analysis.

Results:

Treatment with Haprolid significantly inhibited cell proliferation, migration and invasion in vitro. Furthermore, Haprolid therapy increased E-cadherin and decreased N-cadherin. Haprolid exposure also caused considerable apoptosis (assessed by Annexin V FITC assay, PARP cleavage and caspase activation). Haprolid therapy affected cell cycle G1/S phase transition by down-regulating cyclin A, B, D and pRb levels. Next, Haprolid treatment decreased both total and p-AKT protein levels in a proteasome-independent manner. Finally, NMRI-nu/nu xenografts treated by Haprolid resulted in a 51% tumor growth inhibition.

Conclusion:

Our current work demonstrates that treatment with Haprolid, a novel natural product, can successfully attenuate the carcinogenesis of HCC both in vitro and in vivo. Therefore, Haprolid treatment might be considered as a new therapy for patients with inoperable HCC.