Chronic Cancer-Related Pain: Continuous Perineural Infusion of Local Anesthetics as Alternative to Systemic Analgesic Drugs

Tetracaine hydrochloride induces cell cycle arrest in melanoma by downregulating hnRNPA1

Recent evidence suggests potential benefits of applying local anesthetics in cancer patients. Specifically, tetracaine has a potent antitumor effect in diverse cancers, including neuroblastoma, breast cancer, and melanoma; however, the underlying molecular mechanisms remain unclear. Here, we reported that tetracaine hydrochloride inhibited the growth of melanoma cells and arrested melanoma cells in the G0/G1 phase. Tetracaine hydrochloride treatment resulted in translocation of hnRNPA1 from the nucleoplasm to the nuclear envelope and reduced the protein stability of hnRNPA1 possibly by disrupting the dynamic balance of ubiquitination and neddylation. Elevated hnRNPA1 upregulated cyclin D1 to promote cell cycle in melanoma. The hnRNPA1 overexpression attenuated the effect of tetracaine hydrochloride on melanoma cell growth suppression and cell cycle arrest. Furthermore, melanoma homograft experiments demonstrated that tetracaine hydrochloride suppressed melanoma growth, while hnRNPA1 overexpression alleviated tetracaine's antitumor effect on melanoma. Taken together, our findings suggest that tetracaine hydrochloride exerts a potent antitumor effect on melanoma both in vitro and in vivo, and the effect involves cell cycle arrest induction via downregulation of hnRNPA1.

Effects of Dexmedetomidine as an Analgesic Adjuvant for Surgery of Femur Fracture: A Systematic Review and Meta-Analysis

Patients who undergo surgery of femur fracture suffer the excruciating pain. Dexmedetomidine (DEX) is a unique α2-adrenergic receptor agonist with sedative and analgesic properties, whose efficacy and safety are still unclear for surgery of femur fracture. Randomized controlled trials comparing the effects of addition of DEX to general or local anesthesia in surgery of femur fracture were searched from MEDLINE, EMBASE, and the Cochrane Library database. Patients who received DEX infusion had a significant longer time to rescue analgesia compared with those without DEX coadministration. DEX treatment seemed to reduce the visual analog score; however, the significance did not reach any statistical difference. DEX as an analgesic adjuvant did not reduce the onset of sensory block time, shorten the time to achieve maximum sensory block level, and provide a longer duration of sensory block. The difference in mean sedation scores between 2 groups was not statistically significant. As for adverse effects, DEX therapy significantly increased the rate of hypotension. In conclusion, dexmedetomidine as a local anesthetic adjuvant in femur fracture surgery had a longer duration of rescue analgesia. However, the incidence of hypotension was markedly increased in these patients. It was worth noting that the evidence was of low to moderate quality.

A case report of sustained resolution of cancer pain by continuous perineural infusion of local anaesthetic

BACKGROUND

Opioids are currently offered as first-line treatment for chronic pain from cancer. Continuous regional analgesia could be an alternative to opioids. However, the required duration of catheterization and the sustained analgesic effects of this technique after catheter removal have yet to be clarified.

CASE REPORT

We report the case of a patient with a shoulder desmoid tumour for which monitoring of tumour progression was the sole therapeutic strategy. Analgesia took the form of patient-controlled infusion of local anaesthetics through an interscalene catheter. Due to the need of an MRI control 45 days later, the pump was stopped. The persistence of pain relief 48 hr later led to the decision to remove the perineural catheter. No pain was reported by the patient over the following 42 days.

CONCLUSIONS

In this patient, it would seem that continuous analgesia allowed for a sustained resolution of pain from the shoulder-located tumour. One hypothesis is that local anaesthetics play a direct role in the erasure of pain memory. This hypothesis needs to be tested with a large patient cohort.

SIGNIFICANCE

This case report provides new insights into the treatment of cancer pain. The most interesting finding is that the pain did remained absent after 45 days of continuous infusion of local anaesthetics through an interscalene catheter. We postulated that local anaesthetic drugs have an impact on pain memory.