Nalbuphine Suppresses Leukemia Stem Cells and Acts Synergistically with Chemotherapy Drugs via Inhibiting Ras/Raf/Mek/Erk Pathway.

AIMS: Retrospective clinical studies have shown that opioids could potentially affect the risk of cancer recurrence and metastasis. Better understanding of the effects of opioids on cancer will help to select the optimal anesthetic regimens to achieve better outcomes in cancer patients. BACKGROUND: Increasing evidence has shown the direct effects of opioids on bulk cancer cells and cancer stem cells. Opioid such as nalbuphine is approved to control cancer-associated pain but little is known on their possible cancer effects. OBJECTIVE: To assess the biological effects of nalbuphine on acute myeloid leukemia (AML) differentiated and stem/progenitor CD34+ cells. METHODS: AML CD34+ cells were isolated with colony formation, growth and apoptosis assays performed. Biochemical and immunoblotting analyses were conducted in AML cells exposed to nalbuphine. RESULTS: Nalbuphine at clinically relevant concentrations was active against a panel of AML cell lines with varying IC50. Importantly, nalbuphine augmented the efficacy of cytarabine and daunorubicin in decreasing AML cell viability/ growth. Besides bulk AML cells, we noted that nalbuphine was effective and selective in decreasing viability and colony formation of AML CD34+ cells while sparing normal hematopoietic CD34+ cells. The action of nalbuphine on AML cells is not associated with opioid receptors but via inhibiting Ras/Raf/MEK/ERK signaling pathway. Overexpression of constitutively active Ras partially but significantly reversed the inhibitory effects of nalbuphine on AML cells. CONCLUSION: Our findings reveal the selective anti-AML activity of nalbuphine and its ability in inhibiting Ras signaling. Our work suggests that nalbuphine may be beneficial for leukemia patients.

Differential effects and mechanisms of local anesthetics on esophageal carcinoma cell migration, growth, survival and chemosensitivity.

BACKGROUND: Retrospective analysis and pre-clinical studies suggest that local anesthetics have anti-tumoral effects. However, the association between cancer recurrence and the use of local anesthesia is inconclusive and most reports are based on single local anesthetic results. METHODS: The biological effects (growth, migration and survival) of four common local anesthetics on esophageal carcinoma cells were compared. Biochemical assays on molecules involved in cell migration and proliferation were analyzed. RESULTS: Ropivacaine and bupivacaine significantly inhibited esophageal carcinoma cell migration, at clinically relevant micromolar concentrations. Mepivacaine and lidocaine showed less potent cell migration inhibition than ropivacaine or bupivacaine. All four local anesthetics inhibited cell proliferation. Of note, the effective concentration of anti-proliferative activities requires higher doses. At millimolar concentrations of these local anesthetics, cell apoptosis was moderately affected. Drug combination analysis demonstrated that two of four local anesthetics augmented chemotherapeutic drugs in inhibiting migration. However, all four local anesthetics significantly augmented chemotherapeutic drugs in inhibiting growth and inducing apoptosis. The anti-growth and anti-survival effects of four local anesthetics were attributed to mitochondrial dysfunction and oxidative damage. The anti-migratory effect of local anesthetics is likely through decreasing Rac1 activity. CONCLUSIONS: Our work demonstrates the differential effects and proposes the mechanisms of local anesthetics on esophageal carcinoma cell migration, growth, survival and chemosensitivity.

Bupivacaine inhibits angiogenesis through oxidative stress-dependent inhibition of Akt/mTOR and activation of AMPK.

Although substantial evidence shows the link of local anesthesia and decreased tumor recurrence, the role of amide-linked local anesthetics, particularly bupivacaine, on angiogenesis (a hallmark of tumor progression and metastasis) has not been revealed. In this work, we demonstrate the anti-angiogenic activity of bupivacaine and its underlying mechanism in endothelial cells. We show that bupivacaine inhibits early stage of capillary network formation via suppressing endothelial cell migration without affecting adhesion to matrix. Bupivacaine also inhibits endothelial cell growth and survival. Mechanism analysis indicates that bupivacaine inhibits mitochondrial respiration via decreasing mitochondrial respiratory activity of complex I and II but not IV or V, resulting in energy depletion, oxidative stress, inhibition of Akt/mTOR, and activation of AMPK pathway. The rescue of an antioxidant NAC on the effects of bupivacaine confirms that bupivacaine inhibits angiogenesis through oxidative stress-dependent inhibition of Akt/mTOR and activation of AMPK. Our work clearly demonstrates the inhibitory effects of bupivacaine on angiogenesis via targeting mitochondria. Our findings are in line with the previous work providing the preclinical evidence on how local anesthetics could influence the outcome of cancer patients.

Suppression of mitochondrial respiration with local anesthetic ropivacaine targets breast cancer cells.

BACKGROUND: Retrospective studies on cancer patients who have received local anesthesia show a favorable decrease in tumor metastasis and recurrence. However, the mechanisms underlying the benefits of local anesthesia on cancer recurrence are not well understood. METHODS: In this study, we investigated the biological effects of ropivacaine on breast cancer cells and the mechanisms of its action with emphasis on mitochondrial respiration. RESULTS: Ropivacaine significantly inhibited growth, survival, and anchorage-independent colony formation in two human breast cancer cell lines. It also acted synergistically with a 5-FU in breast cancer cells. Mechanistically, ropivacaine was found to inhibit mitochondrial respiration by suppressing mitochondrial respiratory complex I and II activities, leading to energy depletion, and oxidative stress and damage. The inhibitory effects of ropivacaine in breast cancer cells were abolished in mitochondrial respiration-deficient ρ0 cells, indicating that mitochondrial respiration is essential for the mechanism of action of ropivacaine. Ropivacaine inhibited phosphorylation of Akt, mTOR, rS6, and EBP1 in breast cancer cells, suggesting the association between Akt/mTOR signaling pathway and mitochondrial functions in breast cancer. CONCLUSIONS: Our work clearly demonstrates the inhibitory effects of ropivacaine in breast cancer by disrupting mitochondrial function. Our findings provide a proper understanding of how local anesthetics reduce the risk of tumor recurrence, and thus, support the use of ropivacaine for surgery and to control pain in patients with breast cancer.

Inhibition of gastric cancer by local anesthetic bupivacaine through multiple mechanisms independent of sodium channel blockade.

BACKGROUND: Retrospective studies of patients undergoing cancer surgery suggest the use of local anesthesia may decrease tumor recurrence and improve survival. The mechanisms on the benefits of local anesthesia on cancer recurrence are complex and remain to be elucidated. METHODS: This study investigated the effects of bupivacaine on various cellular activities of gastric cancer using proliferation, migration, apoptosis assay. The underlying mechanism was analyzed focusing on mitochondrial functions and the activities of Rho family members. RESULTS: We show that bupivacaine at low concentrations (eg, 0.01 and 0.05 mM) inhibits migration whereas only at high concentrations (1 and 5 mM) inhibits growth and survival in two human gastric cancer cell lines. Bupivacaine also significantly augments 5-Fluorouracil in inhibiting growth and survival but not migration in gastric cancer cells. In addition, the mechanisms of bupivacaine's action on the growth and survival are different from those on the migration. We demonstrate that bupivacaine inhibits gastric cancer cell growth and survival through inhibiting mitochondrial respiratory complex I and II, leading to decreased mitochondrial oxidation and ATP production. In contrast, bupivacaine inhibits gastric cancer cell migration through decreasing RhoA and Rac1 activities without affecting their expression. Particularly, we demonstrate that bupivacaine inhibits gastric cancer cell migration via inhibiting RhoA/ROCK/MLC pathway. We further show that the action of bupivacaine on mitochondrial functions, RhoA, and Rac1 activities are independent of sodium channel blockade. CONCLUSIONS: Our work demonstrates that bupivacaine has direct anti-cancer activities with the dominant inhibitory effects on gastric cancer migration rather than growth and survival. Our findings also guide a proper understanding and provide underlying mechanisms on how local aesthesis could affect cancer patients.