Tramadol suppresses growth of orthotopic liver tumors via promoting M1 macrophage polarization in the tumor microenvironment.

Tumor-associated macrophages (TAMs) are major infiltrating immune cells in liver cancer. They are polarized to anti-tumor M1 type or tumor-supporting M2 type in a dynamic changing state. Tramadol, a synthetic opioid, exhibits tumor-suppressing effect in several cancers, but whether it plays a role in TAMs polarization is uncertain. In the present study, the potential influence of tramadol on TAMs polarization was explored in liver cancer. An orthotopic murine Hepa 1-6 liver cancer model was constructed. The potential function of tramadol was evaluated by cell viability assay, EdU incorporation assay, flow cytometry, immunofluorescence, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA) assay, T cell proliferation and suppression assays and western blot. We found that tramadol suppressed proliferation and tumor formation of murine Hepa 1-6 cells in vitro and in vivo. Tramadol reprogramed the immune microenvironment to favor M1 macrophage polarization in orthotopic Hepa 1-6 tumors. Moreover, tramadol facilitated M1 macrophage polarization and inhibited M2 macrophage polarization of bone marrow-derived macrophages (BMDMs) and human THP-1 macrophages in vitro. Furthermore, tramadol-treated BMDMs promoted proliferation and activation of splenic CD4+ and CD8+ T cells. Tramadol induced cellular ROS production and mitochondrial dysfunction of BMDMs. Finally, tramadol activated NF-κB signaling in BMDMs and THP-1 macrophages, while inhibition of NF-κB signaling by JSH-23 attenuated the influence of tramadol on macrophage polarization. In conclusion, these data elucidated a novel anti-tumor mechanism of tramadol in liver cancer. Tramadol might be a promising treatment strategy for liver cancer patients.

Local anesthetic bupivacaine inhibits proliferation and metastasis of hepatocellular carcinoma cells via suppressing PI3K/Akt and MAPK signaling.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. Retrospective studies suggest that using local/regional anesthetic (LA/RA) is associated with better outcomes in primary HCC patients. In this study, we evaluated the effects of LA/RA bupivacaine in HCC cells and the underlying molecular mechanisms. The biological functions of bupivacaine in HCC cells were evaluated by transcriptome RNA sequencing, cell viability assay, bromodeoxyuridine incorporation assay, colony formation assay, flow cytometry, western blot, wound healing assay, transwell cell migration assay, tumor xenograft formation, and lung metastasis assay. Bupivacaine suppressed proliferation and induced apoptosis of HepG2 and SNU-449 cells in a time- and dose-dependent manner. Bupivacaine treatment also decreased colony formation, migration, and invasion of HepG2 and SNU-449 cells. In mouse models, bupivacaine repressed tumor xenograft growth and lung metastasis of HepG2 cells. Transcriptome sequencing of HepG2 cells suggested that PI3K/Akt and MAPK signaling pathways were suppressed by bupivacaine treatment. In western blot analysis, bupivacaine reduced the expression of total and phosphorylated Akt, mTOR, and MAPK. Furthermore, reactivated PI3K/Akt and MAPK signaling by EGF or NRG1 partially reversed the effects of bupivacaine on cell growth, colony formation, and invasion of HCC cells. Local anesthetic bupivacaine suppressed proliferation, migration and invasion, and induced apoptosis of HCC cells. Our results provided novel insights into the local anesthetic bupivacaine in the therapy of HCC patients.