Morphine stimulates cancer progression and mast cell activation and impairs survival in transgenic mice with breast cancer

Morphine promotes tumorigenesis and cetuximab resistance via EGFR signaling activation in human colorectal cancer

Morphine, a mu-opioid receptor (MOR) agonist, has been extensively used to treat advanced cancer pain. In particular, in patients with cancer metastasis, both morphine and anticancer drugs are given simultaneously. However, evidence showed that morphine might be a risk factor in promoting the tumor's malignant potential. In this study, we report that treatment with morphine could activate MOR and lead to the promotion of proliferation, migration, and invasion in HCT116 and DLD1 colorectal cancer (CRC) cells with time-concentration dependence. Moreover, morphine can also contribute to cetuximab's drug resistance, a targeted drug widely used to treat advanced CRC by inducing the activation of epidermal growth factor receptor (EGFR). The cell phenotype includes proliferation, migration, invasion, and drug resistance, which may be reversed by MOR knockdown or adding nalmefene, the MOR receptor antagonist. Receptor tyrosine kinase array analysis revealed that morphine selectively induced the transactivation of EGFR. EGFR transactivation resulted in the activation of ERK1/2 and AKT. In conclusion, morphine induces the transactivation of EGFR via MOR. It activates the downstream signal pathway AKT-MTOR and RAS-MAPK, increases proliferation, migration, and invasion, and promotes resistance to EGFR inhibitors in a CRC cell line. Furthermore, we verified that EGFR inhibition by cetuximab strongly reversed the protumoral effects of morphine in vitro and in vivo. Collectively, we provide evidence that morphine-EGFR signaling might be a promising therapeutic target for CRC patients, especially for cetuximab-resistant CRC patients.

Forty-two Million Ways to Describe Pain: Topic Modeling of 200,000 PubMed Pain-Related Abstracts Using Natural Language Processing and Deep Learning-Based Text Generation

OBJECTIVE

Recent efforts to update the definitions and taxonomic structure of concepts related to pain have revealed opportunities to better quantify topics of existing pain research subject areas.

METHODS

Here, we apply basic natural language processing (NLP) analyses on a corpus of >200,000 abstracts published on PubMed under the medical subject heading (MeSH) of "pain" to quantify the topics, content, and themes on pain-related research dating back to the 1940s.

RESULTS

The most common stemmed terms included "pain" (601,122 occurrences), "patient" (508,064 occurrences), and "studi-" (208,839 occurrences). Contrarily, terms with the highest term frequency-inverse document frequency included "tmd" (6.21), "qol" (6.01), and "endometriosis" (5.94). Using the vector-embedded model of term definitions available via the "word2vec" technique, the most similar terms to "pain" included "discomfort," "symptom," and "pain-related." For the term "acute," the most similar terms in the word2vec vector space included "nonspecific," "vaso-occlusive," and "subacute"; for the term "chronic," the most similar terms included "persistent," "longstanding," and "long-standing." Topic modeling via Latent Dirichlet analysis identified peak coherence (0.49) at 40 topics. Network analysis of these topic models identified three topics that were outliers from the core cluster, two of which pertained to women's health and obstetrics and were closely connected to one another, yet considered distant from the third outlier pertaining to age. A deep learning-based gated recurrent units abstract generation model successfully synthesized several unique abstracts with varying levels of believability, with special attention and some confusion at lower temperatures to the roles of placebo in randomized controlled trials.

CONCLUSIONS

Quantitative NLP models of published abstracts pertaining to pain may point to trends and gaps within pain research communities.

A Challenge for Allergologist: Application of Allergy Diagnostic Methods in Mast Cell Disorders

Primary and secondary mast cell activation syndromes (MCAS) can occur in patients with mastocytosis. During the past few years our knowledge about the pathogenesis and disease-triggering mechanisms in MCAS and mastocytosis have increased substantially. Whereas mastocytosis is characterized by an accumulation of neoplastic (clonal) mast cells (MC) in various organ systems, MCAS is defined by a massive and systemic activation of these cells. Mast cells are crucial effector cells in allergic diseases, thus their elevated number and activation can cause severe anaphylactic reactions and MCAS in patients with mastocytosis. However, these cells may also degranulate spontaneously or degranulate in response to non-allergic triggers leading to clinical symptoms. In mastocytosis patients, such symptoms may lead to the diagnosis of a primary MCAS. The diagnosis of a concomitant allergy in mastocytosis patients is challenging. In these patients, a mixed form (primary and secondary) of MCAS may be diagnosed. These patients may also suffer from life-threatening anaphylactic reactions when exposed to allergens. In these cases, the possibility of severe side effects of in vivo provocations can sometimes also limit diagnostic evaluations. In the current article, we discuss the diagnosis and management of patients suffering from mastocytosis and concomitant MCAS, with special emphasis on novel diagnostic tests and management, including allergen microarrays, recombinant allergen analysis, basophil activation tests, optimal prophylaxis, and specific therapies.

Peripherally Acting μ-Opioid Receptor Antagonists in the Management of Postoperative Ileus: a Clinical Review

Postoperative ileus (POI) and constipation are common secondary effects of opioids and carry significant clinical and economic impacts. μ-Opioid receptors mediate opioid analgesia in the central nervous system (CNS) and gastrointestinal-related effects in the periphery. Peripherally acting μ-opioid receptor antagonists (PAMORAs) block the peripheral effects of opioids in the gastrointestinal tract, while maintaining opioid analgesia in the CNS. While most are not approved for POI or postoperative opioid-induced constipation (OIC), PAMORAs have a potential role in these settings via their selective effects on the μ-opioid receptor. This review will discuss recent clinical trials evaluating the safety and efficacy of PAMORAs, with a focus on alvimopan (Entereg^®) and methylnaltrexone (Relistor^®) in patients with POI or postoperative OIC. We will characterize potential factors that may have impacted the efficacy observed in phase 3 trials and discuss future directions for the management and treatment of POI.

β-endorphin at the intersection of pain and cancer progression: Preclinical evidence

We examined the association between endogenous opioid β-endorphin, cancer progression and pain in a transgenic mouse model of breast cancer, with a rat C3(1) simian virus 40 large tumor antigen fusion gene (C3TAg). C3TAg mice develop ductal epithelial atypia at 8 weeks, progression to intra-epithelial neoplasia at 12 weeks, and invasive carcinoma with palpable tumors at 16 weeks. Consistent with invasive carcinoma at 4 months of age, C3TAg mice demonstrate a significant increase in hyperalgesia compared to younger C3TAg or control FVBN mice without tumors. Our data show that the growing tumor contributes to circulating β-endorphin. As an endogenous ligand of mu opioid receptor, β-endorphin has analgesic activity. Paradoxically, we observed an increase in pain in transgenic breast cancer mice with significantly high circulating and tumor-associated β-endorphin. Increased circulating β-endorphin correlates with increasing tumor burden. β-endorphin induced the activation of mitogenic and survival-promoting signaling pathways, MAPK/ERK 1/2, STAT3 and Akt, observed by us in human MDA-MB-231 cells suggesting a role for β-endorphin in breast cancer progression and associated pain.

The association of prescription opioid use with incident cancer: A Surveillance, Epidemiology, and End Results-Medicare population-based case-control study

BACKGROUND

Cancer is the second leading cause of death globally, and researchers seek to identify modifiable risk factors Over the past several decades, there has been ongoing debate whether opioids are associated with cancer development, metastasis, or recurrence. Basic science, clinical, and observational studies have produced conflicting results. The authors examined the association between prescription opioids and incident cancers using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. A complex relation was observed between prescription opioids and incident cancer, and cancer site may be an important determinant.

METHODS

By using linked SEER cancer registry and Medicare claims from 2008 through 2013, a case-control study was conducted examining the relation between cancer onset and prior opioid exposure. Logistic regression was used to account for differences between cases and controls for 10 cancer sites.

RESULTS

Of the population studied (n = 348,319), 34% were prescribed opioids, 79.5% were white, 36.9% were dually eligible (for both Medicare and Medicaid), 13% lived in a rural area, 52.7% had ≥1 comorbidity, and 16% had a smoking-related diagnosis. Patients exposed to opioids had a lower odds ratio (OR) associated with breast cancer (adjusted OR, 0.96; 95% CI, 0.92-0.99) and colon cancer (adjusted OR, 0.90; 95% CI, 0.86-0.93) compared with controls. Higher ORs for kidney cancer, leukemia, liver cancer, lung cancer, and lymphoma, ranging from lung cancer (OR, 1.04; 95% CI, 1.01-1.07) to liver cancer (OR, 1.19; 95% CI, 1.08-1.31), were present in the exposed population.

CONCLUSIONS

The current results suggest that an association exists between prescription opioids and incident cancer and that cancer site may play an important role. These findings can direct future research on specific patient populations that may benefit or be harmed by prescription opioid exposure.

Impact of anesthesia and analgesia techniques on glioblastoma progression. A narrative review

Glioblastoma (GBM) is an aggressive malignant CNS tumor with a median survival of 15 months after diagnosis. Standard therapy for GBM includes surgical resection, radiation, and temozolomide. Recently, anesthetics and analgesics have received attention for their potential involvement in mediating tumor growth. This narrative review investigated whether various members of the 2 aforementioned classes of drugs have a definitive impact on GBM progression by summarizing pertinent in vitro, in vivo, and clinical studies. Recent publications regarding general anesthetics have been inconsistent, showing that they can be pro-tumoral or antitumoral depending on the experimental context. The local anesthetic lidocaine has shown consistent antitumoral effects in vitro. Clinical studies looking at anesthetics have not concluded that their use improves patient outcomes. In vitro and in vivo studies looking at opioid involvement in GBM have demonstrated inconsistent findings regarding whether these drugs are pro-tumoral or antitumoral. Nonsteroidal anti-inflammatory drugs, and specifically COX-2 inhibitors, have shown inconsistent findings across multiple studies looking at whether they are beneficial in halting GBM progression. Until multiple repeatable studies show that anesthetics and analgesics can suppress GBM growth, there is no strong evidence to recommend changes in the anesthetic care of these patients.

Impact of Pain, Opioids, and the Mu-opioid Receptor on Progression and Survival in Patients With Newly Diagnosed Stage IV Pancreatic Cancer

OBJECTIVES

Pancreatic adenocarcinoma is frequently associated with pain requiring opioid therapy. Opioids, however, have been implicated in causing tumor progression, ultimately shortening survival. We examined the impact of pain, opioid use, and the mu-opioid receptor (MOP-R) expression in tumor tissue on progression-free survival and overall survival of patients with metastatic pancreatic cancer.

METHODS

We identified 103 patients with metastatic pancreatic adenocarcinoma receiving chemotherapy and abstracted data from Tumor Registry, in addition to pain, opioid exposure, carbohydrate antigen 19-9 values, survival, and imaging response. MOP-R expression was evaluated using an immunohistochemistry assay. The association of variables with progression-free survival and overall survival was analyzed in univariate and multivariate models.

RESULTS

Patients with low opioid use (<5 mg oral morphine equivalent/d) survived longer than patients with high opioid (HO) use (≥5 mg oral morphine equivalent/d) (median overall survival of 315 vs. 150 d; hazard ratio [HR]=1.79; 95% confidence interval [CI]: 1.13, 2.84). This effect persisted on multivariate models (adjusted HR=2.76; 95% CI: 1.39, 5.48). Low opioid patients tended to respond better to treatment than HO patients, based on carbohydrate antigen 19-9. Patients with low MOP-R expression had longer median survival (230 vs. 193 d), though the HR was not significant (1.15; 95% CI: 0.71, 1.88). Baseline pain was not associated with outcomes.

CONCLUSION

In patients with metastatic pancreatic adenocarcinoma, HO use is associated with decreased survival, but the severity of baseline pain and MOP-R expression score in tumor tissue does not correlate with clinical outcomes.

Opioid-Mediated HIV-1 Immunopathogenesis

Despite the ability of combination antiretroviral therapy to dramatically suppress viremia, the brain continues to be a reservoir of HIV-1 low-level replication. Adding further complexity to this is the comorbidity of drug abuse with HIV-1 associated neurocognitive disorders and neuroHIV. Among several abused drugs, the use of opiates is highly prevalent in HIV-1 infected individuals, both as an abused drug as well as for pain management. Opioids and their receptors have attained notable attention owing to their ability to modulate immune functions, in turn, impacting disease progression. Various cell culture, animal and human studies have implicated the role of opioids and their receptors in modulating viral replication and virus-mediated pathology both positively and negatively. Further, the combinatorial effects of HIV-1/HIV-1 proteins and morphine have demonstrated activation of inflammatory signaling in the host system. Herein, we summarized the current knowledge on the role of opioids on peripheral immunopathogenesis, viral immunopathogenesis, epigenetic profiles of the host and viral genome, neuropathogenesis of SIV/SHIV-infected non-human primates, blood-brain-barrier, HIV-1 viral latency, and viral rebound. Overall, this review provides recent insights into the role of opioids in HIV-1 immunopathogenesis. Graphical abstract.

Role of neuraxial drug delivery in cancer pain therapy

Opioids have long been the mainstay of cancer pain treatment and have been used without any consideration for their effect on cancer growth and long-term prognosis. There is now growing evidence that the continued use of opioids for this indication should be reviewed and even reconsidered. Although current evidence and literature covering this subject is mixed and does not yet allow for a clear determination to be made about safety, there is enough data to support the search for new treatment paradigms, beginning with anesthesia for oncologic surgery and management of cancer pain over the disease course.

Anaesthesia and cancer: can anaesthetic drugs modify gene expression?

Cancer remains a primary cause of morbidity and mortality worldwide, and its incidence continues to increase. The most common cause of death in cancer patients is tumour recurrence. Surgery is the gold standard in the treatment of most tumours. However, cancer surgery can lead to the release of tumour cells into the systemic circulation. Surgical stress and several perioperative factors have been suggested to boost tumour growth, thereby increasing the risk of metastatic recurrence. Preclinical and clinical studies suggest that anaesthetics and adjuvants administered during the perioperative period may impact cancer recurrence and survival. This document summarises the current evidence regarding the effects of anaesthetic drugs and analgesic techniques on the immune system, systemic inflammatory response and tumour cells, as well as their impact on cancer recurrence.

How I treat pain in hematologic malignancies safely with opioid therapy

The field of malignant hematology has experienced extraordinary advancements with survival rates doubling for many disorders. As a result, many life-threatening conditions have since evolved into chronic medical ailments. Paralleling these advancements have been increasing rates of complex hematologic pain syndromes, present in up to 60% of patients with malignancy who are receiving active treatment and up to 33% of patients during survivorship. Opioids remain the practice cornerstone to managing malignancy-associated pain. Prevention and management of opioid-related complications have received significant national attention over the past decade, and emerging data suggest that patients with cancer are at equal if not higher risk of opioid-related complications when compared with patients without malignancy. Numerous tools and procedural practice guides are available to help facilitate safe prescribing. The recent development of cancer-specific resources directing algorithmic use of validated pain screening tools, prescription drug monitoring programs, urine drug screens, opioid use disorder risk screening instruments, and controlled substance agreements have further strengthened the framework for safe prescribing. This article, which integrates federal and organizational guidelines with known risk factors for cancer patients, offers a case-based discussion for reviewing safe opioid prescribing practices in the hematology setting.

Propofol-based total intravenous anesthesia improves survival compared to desflurane anesthesia in gastric cancer surgery: A retrospective analysis

Surgical management of cancer may induce stress and increase the likelihood of cancer metastasis and recurrence. Appropriate surgical and anesthetic techniques may affect the patient's outcome. Although numerous studies have been performed, conflicting results have been obtained regarding the effect of anesthetic techniques on the outcome of patients with cancer. We conducted this study to evaluate the association of anesthetic techniques with overall and recurrence-free survival in patients who had undergone gastric cancer surgery.This retrospective study reviewed the electronic medical records of patients, who had visited our hospital and had been diagnosed with gastric cancer between July 1st, 2006 to June 30th, 2016. Univariate analysis of the potential prognostic factors was performed using the log-rank test for categorical factors, and parameters with a P-value < .05 at the univariate step were included in the multivariate regression analysis. Propensity Score Matching was performed to account for differences in baseline characteristics: propofol or desflurane, in a 1:1 ratio.A total of 408 patients anesthetized with desflurane (218) and propofol (190) were eligible for analysis. After propensity matching, 167 patients remained in each group. The overall mortality rate was significantly higher in the desflurane group (56%) than in the propofol group (34%) during follow-up (P < .001). In addition, a greater percentage of patients in the desflurane group (41%) exhibited postoperative metastasis than those in the propofol group (19%, P < .001).The authors found some association between types of anesthesia used and the long-term prognosis of gastric cancer. Propofol-based total intravenous anesthesia improved survival and reduced the risk of recurrence and metastasis during the 5-year follow-up period after gastric cancer surgery.

Analgesic and opioid-sparing effects of single-shot preoperative paravertebral block for radical mastectomy with immediate reconstruction: A retrospective study with propensity-adjusted analysis

BACKGROUND

Before radical mastectomy with immediate latissimus dorsi flap reconstruction, single-shot paravertebral block (PVB) can be added to general anesthesia to improve analgesia. As this technique was introduced in 2014 in our centre, our aim was to retrospectively assess its clinical effects.

METHODS

Among 175 patients who underwent surgery over four years (40 receiving PVB), we studied the intra-operatively administered doses of opioids and vasopressors, postoperative pain as estimated by a composite score based on the intensity scores for maximum postoperative pain and the amounts of analgesic drugs, and the report of postoperative nausea/vomiting (PONV). The effect of PVB on these outcomes was tested by propensity-matched comparisons, after a propensity score based on the patient's age, body mass index, ASA and Apfel scores, was calculated. Depending on the outcomes, results are expressed as odds ratios (OR) or regression coefficients (RC), with their 95% confidence interval limits.

RESULTS

PVB reduced the doses of intraoperative opioids (OR for comparisons between the 2nd and 3rd tercile to the 1st tercile, respectively: 0.39 (0.21; 0.67) and 0.10 (0.05; 0.21)). It increased the doses of intraoperative vasopressors (CR = 1.94 (0.89; 2.93). It reduced the composite score for postoperative pain (CR = -0.80 (-1.04; -0.56), and the occurrence of PONV (OR = 0.21 (0.14; 0.37).

CONCLUSIONS

Despite a higher risk of intraoperative hypotension, single-shot PVB seems to markedly improve postoperative analgesia and reduce the amounts of opioids. This could offer many clinical advantages in this type of cancer surgery.

Opioids and Cancer Mortality

OPINION STATEMENT

Opioids are the gold standard for the treatment of cancer-related pain. Preclinical studies have associated opioids with cancer progression and overall survival. In mice models, opioids have been shown to possess pro-tumor activity secondary to immunosuppression, migration of tumor cells, increased activity of vascular endothelial growth factor receptors, and angiogenesis leading to tumor progression. In contrast, opioids have also been associated with having antitumor activity by activation of apoptosis and phagocytosis. However, high-quality randomized controlled trials in humans that are focused on the association between opioids and survival in cancer patients are lacking, which underscores the importance of being cautious when interpreting the results of the preclinical studies. Cancer-related pain is complex and multifactorial and may worsen as the disease progresses leading to higher opioid utilization. Moreover, cancer pain by itself has been associated with poor survival. The survival in these advanced cancer patients taking opioids may be more likely to be associated with cancer progression and not the opioid use. Adequate treatment of cancer pain has the potential to improve quality of life and performance status, highlighting the importance of continuing to use opioids to manage pain efficiently. More research is clearly needed.

Evaluation of Receptor Affinity, Analgesic Activity and Cytotoxicity of a Hybrid Peptide, AWL3020

In the present contribution we report design, synthesis and evaluation of receptor affinity, analgesic activity and cytotoxicity of a hybrid peptide, AWL3020. The peptide includes two pharmacophores, one of δ-opioid receptor (δOR) agonists and one of neurokinin-1 receptor (NK1R) antagonists. The design was motivated by the desire to obtain a compound with strong analgesic action and potential additional antiproliferative action. The compound displays high δOR affinity (IC50 = 29.5 nM). On the other hand, it has only poor affinity for the NK1R (IC50 = 70.28 μM). The substance shows good analgesic action which is however weaker than that of morphine. Regarding the effect on proliferation, the compound exhibits no pro-proliferative action in the assayed range. In higher concentrations, it has also cytotoxic activity. This effect is however not selective. The strongest effect of AWL3020 was found for melanoma MeW164 cell line (EC50 = 46.27 μM in reduction of cell numbers after a few days of incubation; EC50 = 37.78 μM in MTT assay).

Opioids in Cancer Development, Progression and Metastasis: Focus on Colorectal Cancer

OPINION STATEMENT

So far, opioids have been successfully used to reduce cancer pain in patients in order to improve their quality of life. However, the use of opioids leads to numerous side effects such as constipation, drowsiness, nausea, itching, increased sweating and hormonal changes. In this review, we described the action of opioids in several molecular pathways significant for maintenance of the intestinal homeostasis including the impact on the intestinal epithelium integrity, changes in microbiome composition, modulation of the immune system or induction of apoptosis and inhibition of angiogenesis. We summed up the role of individual opioids in the processes involved in the growth and development of cancer and elucidated if targeting opioid receptors may constitute novel therapeutic option in colon cancer.

Suppression of Human Natural Killer Cells by Different Classes of Opioids

BACKGROUND

The use of regional and other opioid-sparing forms of anesthesia has been associated with a decrease in the recurrence of certain malignancies. Direct suppression of human natural killer cells by opioids has been postulated to explain this observation. However, the effect of different classes of opioids on suppression of natural killer cell cytotoxicity has not been systematically characterized.

METHODS

After confirming that freshly isolated natural killer cells from peripheral human blood express opioid receptors, cells were incubated with increasing concentrations of clinically used or receptor-specific opioid agonists. We also evaluated the effect of pretreatment with receptor-specific antagonists or naloxone. Treated natural killer cells were then coincubated with a carboxyfluorescein succinimidyl ester-labeled target tumor cell line, K562. Annexin V staining was used to compare the percent of tumor cell apoptosis in the presence of opioid-pretreated and untreated natural killer cells. Treated samples were compared to untreated samples using Kruskal-Wallis tests with a post hoc Dunn correction.

RESULTS

Morphine, methadone, buprenorphine, loperamide, [D-Ala2, N-MePhe4, Gly-ol]-enkephalin, and U-50488 significantly decreased natural killer cell cytotoxicity. When natural killer cells were pretreated with naloxone, cyprodime, and nor-binaltorphimine before exposure to morphine, there was no difference in natural killer cytotoxicity, compared to the amount observed by untreated natural killer cells. Fentanyl, O-desmethyltramadol, and [D-Pen2,D-Pen5] enkephalin did not change natural killer cell cytotoxicity compare to untreated natural killer cells.

CONCLUSIONS

Incubation of isolated natural killer cells with certain opioids causes a decrease in activity that is not observed after naloxone pretreatment. Suppression of natural killer cell cytotoxicity was observed with μ- and κ-receptor agonists but not δ-receptor agonists. These data suggest that the effect is mediated by μ- and κ-receptor agonism and that suppression is similar with many clinically used opioids.

Comparison of Biochemical Recurrence After Robot-assisted Laparoscopic Radical Prostatectomy with Volatile and Total Intravenous Anesthesia

Aims: Recurrence after cancer surgery is a major concern in patients with cancer. Growing evidence from preclinical studies has revealed that various anesthetics can influence the immune system in different ways. The current study compared the long-term biochemical recurrence of prostate cancer after robot-assisted laparoscopic radical prostatectomy (RALP) in terms of selection of anesthetic agent between total intravenous anesthesia (TIVA) with propofol/remifentanil and volatile anesthetics (VA) with sevoflurane or desflurane/remifentanil. Methods: We followed up oncologic outcomes of patients who underwent RALP from two previous prospective randomized controlled trials, and the outcomes of those who received TIVA (n = 64) were compared with those who received VA (n = 64). The follow-up period lasted from November 2010 to March 2019. Results: Both TIVA and VA groups showed identical biochemical recurrence-free survivals at all-time points after RALP. The following predictive factors of prostate cancer recurrence were determined by Cox regression: colloid input [hazard ratio (HR)=1.002, 95% confidence interval (CI): 1.000-1.003; P = 0.011], initial prostate-specific antigen level (HR=1.025, 95% CI: 1.007-1.044; P = 0.006), and pathological tumor stage 3b (HR=4.217, 95% CI:1.207-14.735; P = 0.024), but not the anesthetic agent. Conclusions: Our findings demonstrate that both TIVA with propofol/remifentanil and VA with sevoflurane or desflurane/remifentanil have comparable effects on oncologic outcomes in patients undergoing RALP.

The aetiology of social deficits within mental health disorders: The role of the immune system and endogenous opioids

The American National Institute for Mental Health (NIMH) has put out a set of research goals that include a long-term plan to identify more reliable endogenous explanations for a wide variety of mental health disorders (Insel, 2013). In response to this, we have identified a major symptom that underlies multiple mental health disorders - social bonding dysfunction. We suggest that endogenous opioid abnormalities can lead to altered social bonding, which is a symptom of various mental health disorders, including depression, schizophrenia and ASD. This article first outlines how endogenous opioids play a role in social bonding. Then we show their association with the body's inflammation immune function, and review recent literature linking inflammation to mental health 'immunophenotypes'. We finish by explaining how these immunophenotypes may be caused by alterations in the endogenous opioid system. This is the first overview of the role of inflammation across multiple disorders where we provide a biochemical explanation for why immunophenotypes might exist across diagnoses. We propose a novel mechanism of how the immune system may be causing 'sickness-type' behaviours (fatigue, appetite change, social withdrawal and inhibited motivation) in those who have these immunophenotypes. We hope that this novel aetiology can be used as a basis for future research in mental health.

Low- versus high-dose intraoperative opioids: A systematic review with meta-analyses and trial sequential analyses

BACKGROUND

Opioid-induced hyperalgesia is a state of nociceptive sensitisation secondary to opioid administration. The objective of this meta-analysis was to test the hypothesis that high-dose intraoperative opioids contribute to increased post-operative pain and hyperalgesia when compared with a low-dose regimen in patients under general anaesthesia.

METHODS

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement guidelines and rated the certainty of evidence with the Grading of Recommendations, Assessment, Development and Evaluation system. Only trials investigating pain outcomes and comparing two different dosages of the same intraoperative opioid in patients under general anaesthesia were included. The primary outcome was pain score (analogue scale, 0-10) at 24 post-operative hours. Secondary outcomes included pain score and cumulative intravenous morphine equivalents (mg) consumed at 2 post-operative hours, together with mechanical pain threshold (g·mm^-2 ).

RESULTS

Twenty-seven randomised controlled trials, including 1630 patients, were identified. Pain score at rest at 24 post-operative hours was increased in the high-dose group (mean difference [95% CI]: -0.2 [-0.4, -0.1]; trial sequential analysis-adjusted CI: -0.4, -0.02; low certainty of evidence). Similarly, at 2 post-operative hours, both pain score (mean difference [95% CI]: -0.4 [-0.6, -0.2]; low certainty of evidence) and cumulative intravenous morphine equivalents consumed (mean difference [95% CI]: -1.6 mg [-2.6, -0.7]; low certainty of evidence) were significantly higher in the high-dose group. Finally, the threshold for mechanical pain was significantly lower in the high-dose group (mean difference to pressure [95% CI]: 3.8 g·mm^-2 [1.8, 5.8]; low certainty of evidence).

CONCLUSIONS

There is low certainty of evidence that high-dose intraoperative opioid administration increases pain scores in the post-operative period, when compared with a low-dose regimen.

Impact of perioperative pain management on cancer recurrence: an ASRA/ESRA special article

Cancer causes considerable suffering and 80% of advanced cancer patients experience moderate to severe pain. Surgical tumor excision remains a cornerstone of primary cancer treatment, but is also recognized as one of the greatest risk factors for metastatic spread. The perioperative period, characterized by the surgical stress response, pharmacologic-induced angiogenesis, and immunomodulation results in a physiologic environment that supports tumor spread and distant reimplantation.In the perioperative period, anesthesiologists may have a brief and uniquewindow of opportunity to modulate the unwanted consequences of the stressresponse on the immune system and minimize residual disease. This reviewdiscusses the current research on analgesic therapies and their impact ondisease progression, followed by an evidence-based evaluation of perioperativepain interventions and medications.

A Breast Cancer Survivor's Self-Controlled Case Report: Methylprednisolone Acetate Provided a Week Longer Analgesia Than Dexamethasone Sodium Phosphate via Thoracic Paravertebral Blockade

Proper perioperative pain control with opioid-sparing techniques that extend into post-discharge arena is desirable yet hard to accomplish in breast cancer patients. We here reported a case where we took advantage of long-acting local anesthetics in conjunction with glucocorticoids of different hydrophilic/lipophilic properties and achieved prolonged analgesia for days after single administration thoracic paravertebral blockade. Further exploration into the potential effects of long-acting glucocorticoids in breast cancer patients through peripheral nerve blockage is warranted.

Effects of Intraperitoneal and Intrathecal Morphine Analgesia on the Expression of μ-Opioid Receptors in Bone Cancer Pain Rats

Backgrounds

This study compared analgesic effects and μ-opioid receptor expression levels during long-term intraperitoneal and intrathecal treatment in a bone cancer pain rat.

Methods

Twenty-four female Sprague-Dawley rats were injected Walker 256 tumor cells into the femur to create a bone cancer pain model. The control group was injected with saline intraperitoneally and intrathecally. The intraperitoneal group was injected with morphine intraperitoneally and saline intrathecally. The intrathecal group was injected saline intraperitoneally and morphine intrathecally. Changes in pain threshold, μ-opioid receptor expression levels in spinal cord, and tumor tissue were compared between 3 groups.

Results

The intrathecal morphine group and the intraperitoneal group showed no difference in analgesia effects (P > .05). Western blot and immunohistochemical staining of μ-opioid receptors demonstrated that its level in the intrathecal group was significantly lower than the intraperitoneal group (P < .05) and without significant difference with the control group (P > .05). The expression levels of μ-opioid receptor in the spinal cord tissue did not reveal a difference among these 3 groups (P > .05).

Conclusion

Intrathecal group and intraperitoneal group showed significant difference in μ-opioid receptor expressions although with no difference in analgesia effects. Long-term intrathecal morphine administration provided similar analgesia compared to systemic morphine.

Effect of Equipotent Doses of Propofol versus Sevoflurane Anesthesia on Regulatory T Cells after Breast Cancer Surgery

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Clusters of differentiation 39 and 73, enzymes expressed on the surface of regulatory T cells, promote cancer recurrence and metastasis by suppressing immune cells. The authors hypothesized that propofol is less immunosuppressive than volatile anesthetics. The objective of this randomized trial was to compare the changes in cluster of differentiation 39 and 73 expression on regulatory T cells between propofol- and sevoflurane-based anesthesia during breast cancer surgery.

METHODS

A total of 201 patients having breast cancer surgery were randomly assigned and analyzed (n = 99 for propofol, n = 102 for sevoflurane). Blood samples were obtained immediately before anesthesia induction and 1 and 24 h postoperatively. The frequency of cluster of differentiation 39 and 73 expression on circulating regulatory T cells (primary outcome) and the frequency of circulating type 1 and type 17 helper T cells, natural killer cells, and cytotoxic T cells were investigated. Serum cytokines and the neutrophil-to-lymphocyte ratio were also evaluated.

RESULTS

Changes in cluster of differentiation 39 and 73 expression on regulatory T cells over time did not differ with propofol and sevoflurane groups (difference [95% confidence interval]: 0.01 [-2.04 to 2.06], P = 0.995 for cluster of differentiation 39; -0.93 [-3.12 to 1.26], P = 0.403 for cluster of differentiation 73). There were no intergroup differences in type 1, type 17 helper T cells, natural killer cells, cytotoxic T cells, cytokines, or the neutrophil-to-lymphocyte ratio.

CONCLUSIONS

Changes in immune cells were similar with propofol and sevoflurane during breast cancer surgery. The effect of anesthetics on the perioperative immune activity may be minimal during cancer surgery.

Naloxone Counteracts the Promoting Tumor Growth Effects Induced by Morphine in an Animal Model of Triple-negative Breast Cancer

BACKGROUND/AIM

Our group has previously demonstrated, in in vitro and in vivo studies on triple-negative breast cancer, that morphine promoted breast cancer progression whereas naloxone was able to reduce it. In this subsequent investigation, we aimed to assess the combinatorial effects of these two drugs in an animal model of triple negative breast cancer.

MATERIALS AND METHODS

In order to evaluate the in vivo effects of the combination of morphine and naloxone in human breast cancer, a mouse model of human triple-negative breast cancer was generated by injecting the MDA-MB-231 cells subcutaneously in nude mice. Naloxone and morphine were daily intraperitoneally co-injected in mice for 4 weeks at two different doses. Micro-vessel formation was detected by fluorescein isothiocyanate-dextran (100 μl) injected into the lateral tail vein of mice and confirmed by immunohistochemistry for PECAM-1 on mice tumor sections.

RESULTS

In vivo experiments showed that naloxone was able to counteract the promoting effects of morphine on tumor growth. No impairment of micro-vessel formation in tumors of mice treated with the two drugs was observed.

CONCLUSION

Herein, we demonstrated that naloxone was able to counteract the promoting effects of morphine on tumor growth without impairing micro-vessel formation.

Morphine contributed to the deterioration of cancer via miR-543/MARCKS/FcγR-mediated phagocytosis pathway

OBJECTIVES

It has been confirmed that morphine was detrimental to patients with cancers. Hence, we aimed to reveal a certain mechanism of morphine in cancer development.

METHODS

Microarray and GSEA analysis were utilized to seek for differently expressed genes and pathway.

KEY FINDINGS

Bioinformatics analysis identified that downregulation of MARCKS and upregulation of miR-543 in samples treated with morphine. FcγR-mediated phagocytosis pathway was illustrated to be upregulated in the control. PANC-1 and DU145 cell viability was increased but apoptosis was declined as morphine concentration went up from 10^-8 to 10^-6  mol/l. On the other curve, the viability was reduced and apoptosis was elevated from 10^-6 to 10^-5  mol/l. The expression of miR-543 ran the same trend as cell viability. Assays in vivo and in vitro validated that miR-543 facilitated cell viability, tumour growth, levels of CA199 and PSA, whereas inhibited apoptosis. MARCKS could target and inhibit miR-543 expression, which exhibited an opposite effect on cancer progression. MiR-543 blocked but MARCKS activated FcγR-mediated phagocytosis pathway.

CONCLUSIONS

Morphine at 10^-6  mol/l could benefit miR-543 expression to inhibit MARCKS expression, consequently, blocking FcγR-mediated phagocytosis pathway, which contributed to the cancer progression in vitro and in vivo.

Nalbuphine suppresses breast cancer stem-like properties and epithelial-mesenchymal transition via the AKT-NFκB signaling pathway

BACKGROUND

Cancer pain is a debilitating disorder of human breast cancer and a primary determinant of the poor quality of life, and relieving pain is fundamental strategy in the cancer treatment. However, opioid analgesics, like morphine and fentanyl, which are widely used in cancer pain treatment have been reported to enhance stem-like traits and epithelial-mesenchymal transition (EMT) of breast cancer cells. As such, it is vital to make the best choice of analgesic for breast cancer management.

METHODS

MTT assays and colony formation assays were performed to examine tumor cell proliferation upon nalbuphine treatment. RT-PCR, western blot, flow cytometry, sphere formation, immunohistochemistry, transwell assays, wound healing assays and mouse xenograft were used to assess the biological effects of nalbuphine treatment.

RESULTS

Nalbuphine inhibited breast cancer cell growth and tumorigenesis, with little effect on noncancerous breast cell lines. Nalbuphine suppressed cancer stem-like traits and EMT in both breast cancer cells and mouse xenograft tumor tissues. Additionally, activation of AKT reversed the nalbuphine-induced inhibition of cancer stem-like properties, tumorigenesis and EMT.

CONCLUSIONS

Our results demonstrate a new role of nalbuphine in inhibiting cancer stem-like properties and EMT in addition to relieving pain, which suggests that nalbuphine may be effective in breast cancer treatment.

Lung cancer cells release high mobility group box 1 and promote the formation of neutrophil extracellular traps

Lung cancer is the leading cause of cancer-associated mortality. Tumor-associated neutrophils represent a large portion of inflammatory cells within the lung tumor microenvironment. However, the roles of neutrophil extracellular traps (NETs) in lung cancer remain unclear. In the present study, it was identified that Lewis lung carcinoma cells actively released the danger-associated molecular pattern protein high mobility group box 1 (HMGB1). Furthermore, HMGB1 in lung cancer cell supernatants promoted the formation of neutrophil extracellular traps (NETs), which was dependent on Toll-like receptor 4 (TLR4). The downstream molecules of TLR4, including myeloid differentiation factor 88, TIR-domain-containing adapter-inducing interferon-β, p38 mitogen-activated protein kinases (p38 MAPKs) and extracellular signal-regulated kinases (ERKs), were activated during the formation of NETs. In addition, inhibition of p38 MAPKs or ERKs significantly decreased NETs. Morphine, an additional ligand for TLR4, aggravated the NETs induced by lung cancer cells. The present study revealed novel mechanisms in tumor-associated NET formation.

How Anesthetic, Analgesic and Other Non-Surgical Techniques During Cancer Surgery Might Affect Postoperative Oncologic Outcomes: A Summary of Current State of Evidence

The question of whether anesthetic, analgesic or other perioperative intervention during cancer resection surgery might influence long-term oncologic outcomes has generated much attention over the past 13 years. A wealth of experimental and observational clinical data have been published, but the results of prospective, randomized clinical trials are awaited. The European Union supports a pan-European network of researchers, clinicians and industry partners engaged in this question (COST Action 15204: Euro-Periscope). In this narrative review, members of the Euro-Periscope network briefly summarize the current state of evidence pertaining to the potential effects of the most commonly deployed anesthetic and analgesic techniques and other non-surgical interventions during cancer resection surgery on tumor recurrence or metastasis.

Morphine promotes neovascularizing retinopathy in sickle transgeneic mice

Neovascularizing retinopathy is a significant complication of sickle cell disease (SCD), occurring more frequently in HbSC than HbSS disease. This risk difference is concordant with a divergence of angiogenesis risk, as identified by levels of pro- vs anti-angiogenic factors in the sickle patient's blood. Because our prior studies documented that morphine promotes angiogenesis in both malignancy and wound healing, we tested whether chronic opioid treatment would promote retinopathy in NY1DD sickle transgenic mice. After 10 to 15 months of treatment, sickle mice treated with morphine developed neovascularizing retinopathy to a far greater extent than either of the controls (sickle mice treated with saline and wild-type mice treated identically with morphine). Our dissection of the mechanistic linkage between morphine and retinopathy revealed a complex interplay among morphine engagement with its μ opioid receptor (MOR) on retinal endothelial cells (RECs); morphine-induced production of tumor necrosis factor α and interleukin-6 (IL-6), causing increased expression of both MOR and vascular endothelial growth factor receptor 2 (VEGFR2) on RECs; morphine/MOR engagement transactivating VEGFR2; and convergence of MOR, VEGFR2, and IL-6 activation on JAK/STAT3-dependent REC proliferation and angiogenesis. In the NY1DD mice, the result was increased angiogenesis, seen as neovascularizing retinopathy, similar to the retinal pathology occurring in humans with SCD. Therefore, we conclude that chronic opioid exposure, superimposed on the already angiogenic sickle milieu, might enhance risk for retinopathy. These results provide an additional reason for development and application of opioid alternatives for pain control in SCD.

Effect of chronic opioid therapy on pain and survival in a humanized mouse model of sickle cell disease

Chronic morphine treatment leads to decreased survival in control mice, but not in sickle mice. Chronic morphine treatment leads to hyperalgesia in sickle mice, but does not lead to analgesic tolerance.

Short- and Long-term Opioid Use in Patients with Oral and Oropharynx Cancer

OBJECTIVE

Opioid use and abuse is a national health care crisis, yet opioids remain the cornerstone of pain management in cancer. We sought to determine the risk of acute and chronic opioid use with head and neck squamous cell cancer (HNSCC) treatment.

STUDY DESIGN

Retrospective population-based study.

SETTING

Surveillance, Epidemiology and End Results (SEER)-Medicare database from 2008 to 2011.

SUBJECTS AND METHODS

In total, 976 nondistant metastatic oral cavity and oropharynx patients undergoing cancer-directed treatment enrolled in Medicare were included. Opiate use was the primary end point. Univariate and multivariable logistic analyses were completed to determine risk factors.

RESULTS

Of the patients, 811 (83.1%) received an opioid prescription during the treatment period, and 150 patients (15.4%) had continued opioid prescriptions at 3 months and 68 (7.0%) at 6 months. Opioid use during treatment was associated with prescriptions prior to treatment (odds ratio [OR], 3.28; 95% confidence interval [CI], 2.11-5.12) and was least likely to be associated with radiation treatment alone (OR, 0.35; 95% CI, 0.18-0.68). Risk factors for continued opioid use at both 3 and 6 months included tobacco use (OR, 2.23; 95% CI, 1.05-4.71 and OR, 3.84; 95% CI, 1.44-10.24) and opioids prescribed prior to treatment (OR, 3.84; 95% CI, 2.45-5.91 and OR, 3.56; 95% CI, 1.95-6.50). Oxycodone prescribed as the first opioid was the least likely to lead to ongoing use at 3 and 6 months (OR, 0.33; 95% CI, 0.17-0.62 and OR, 0.26; 95% CI, 0.10-0.67).

CONCLUSION

Patients with oral/oropharyngeal cancer are at a very high risk for receiving opioids as part of symptom management during treatment, and a significant portion continues use at 3 and 6 months after treatment completion.

Mast cell-neural interactions contribute to pain and itch

Mast cells are best recognized for their role in allergy and anaphylaxis, but increasing evidence supports their role in neurogenic inflammation leading to pain and itch. Mast cells act as a "power house" by releasing algogenic and pruritogenic mediators, which initiate a reciprocal communication with specific nociceptors on sensory nerve fibers. Consequently, nerve fibers release inflammatory and vasoactive neuropeptides, which in turn activate mast cells in a feedback mechanism, thus promoting a vicious cycle of mast cell and nociceptor activation leading to neurogenic inflammation and pain/pruritus. Mechanisms underlying mast cell differentiation, activation, and intercellular interactions with inflammatory, vascular, and neural systems are deeply influenced by their microenvironment, imparting enormous heterogeneity and complexity in understanding their contribution to pain and pruritus. Neurogenic inflammation is central to both pain and pruritus, but specific mediators released by mast cells to promote this process may vary depending upon their location, stimuli, underlying pathology, gender, and species. Therefore, in this review, we present the contribution of mast cells in pathological conditions, including distressing pruritus exacerbated by psychologic stress and experienced by the majority of patients with psoriasis and atopic dermatitis and in different pain syndromes due to mastocytosis, sickle cell disease, and cancer.

Epidural anesthesia and cancer outcomes in bladder cancer patients: is it the technique or the medication? A matched-cohort analysis from a tertiary referral center

BACKGROUND

The perioperative period can be a critical period with long-term implications on cancer-related outcomes. In this study, we evaluate the influence of regional anesthesia on cancer-specific outcomes in a radical cystectomy (RC) cohort of patients.

METHODS

We performed a retrospective analysis of patients with clinically-nonmetastatic urothelial carcinoma of the bladder who underwent RC at our institution from 2008 to 2012. Patients were retrospectively registered and stratified based on two anesthetic techniques: perioperative epidural analgesia with general anesthesia (epidural) versus general anesthesia alone (GA). Epidural patients received a sufentanil-based regimen (median intraoperative sufentanil dose 50 mcg (45,85). Propensity-score was used to make 1:1 case-control matching. Cumulative risk of recurrence with competing risks was calculated based on anesthetic technique. Kaplan-Meier curves were used to compare recurrence-free (RFS) and cancer-specific survival (CSS). Univariable and multivariable analyses were performed with Cox proportional hazard regression models for RFS and CSS.

RESULTS

Only patients with complete data on anesthetic technique were included. Out of 439 patients, 215-pair samples with complete follow-up were included in the analysis. Median follow-up was 41.4 months (range: 0.20-101). Patients with epidurals received higher median total intravenous morphine equivalents (ivMEQ) versus those in the GA group (75 (11-235) vs. 50 ivMEQ (7-277), p < 0.0001). Cumulative risk of recurrence at two years was 25.2% (19.6, 31.2) for epidural patients vs. 20.0% (15.0, 25.7) for GA patients (Gray test p = 0.0508). Epidural analgesic technique was a significant predictor of worse RFS (adjusted HR = 1.67, 1.14-2.45; p = 0.009) and CSS (HR = 1.53, 1.04-2.25; p = 0.030) on multivariable analyses.

CONCLUSIONS

Epidural anesthesia using sufentanil was associated with worse recurrence and disease-free survival in bladder cancer patients treated with surgery. This may be due use of epidural sufentanil or due to the increased total morphine equivalents patient received as a consequence of this drug.

Morphine as a treatment of cancer-induced pain-is it safe? A review of in vivo studies and mechanisms

Morphine has been used in the treatment of pain for centuries. It is commonly used by oncology in terminal cancer cases and by surgery perioperatively for oncology surgery. Its extra-analgesic effects on cancer have been described extensively but conflicting results abound. It has been shown to have varying effects on tumour progression, cell proliferation, tumour invasion, angiogenesis, immune function, and metastatic potential. In vivo studies on the effects of morphine and the mu-opioid receptor on tumours are discussed below. Mechanisms involved are also discussed, drawn from a combination of both in vivo and in vitro methods. At present, no consensus can be drawn from data collected, and further studies are necessary to elicit the safest method and agent for analgesia in oncology patients.

A Pharmacological Rationale to Reduce the Incidence of Opioid Induced Tolerance and Hyperalgesia: A Review

Chronic pain is an important health and social problem. Misuse and abuse of opioids in chronic non-cancer pain management seem to be a huge problem, in some countries. This could probably affect the normal use of such analgesics in patients in need of them. Basic and clinical researches should find the solution to mitigate the potential damage. Dysregulation of mast cell and microglia activation plays an important role in the pathogenesis and management of chronic pain. Persistent mast cell activation sensitizes nociceptors and initiates central nervous system inflammatory processes, involving microglial cell activation and sensitization of spinal somatosensory neurons. Exposure of mast cells and microglia to opioids is well known to provoke activation of these non-neuronal immune cell populations, thereby contributing to an exacerbation of pro-inflammatory and pro-nociceptive processes and promoting, over the long-term, opioid-induced hyperalgesia and tolerance. This review is intended to provide the reader with an overview of the role for these non-neuronal cells in opioid-induced chronic pain and tolerance as a consequence of prolonged exposure to these drugs. In addition, we will examine a potential strategy with the aim to modulate opioid-induced over-activation of glia and mast cells, based on endogenous defense mechanisms and fatty acid amide signaling molecules.

Update of the Scientific Opinion on opium alkaloids in poppy seeds

Poppy seeds are obtained from the opium poppy (Papaver somniferum L.). They are used as food and to produce edible oil. The opium poppy plant contains narcotic alkaloids such as morphine and codeine. Poppy seeds do not contain the opium alkaloids, but can become contaminated with alkaloids as a result of pest damage and during harvesting. The European Commission asked EFSA to provide an update of the Scientific Opinion on opium alkaloids in poppy seeds. The assessment is based on data on morphine, codeine, thebaine, oripavine, noscapine and papaverine in poppy seed samples. The CONTAM Panel confirms the acute reference dose (ARfD) of 10 μg morphine/kg body weight (bw) and concluded that the concentration of codeine in the poppy seed samples should be taken into account by converting codeine to morphine equivalents, using a factor of 0.2. The ARfD is therefore a group ARfD for morphine and codeine, expressed in morphine equivalents. Mean and high levels of dietary exposure to morphine equivalents from poppy seeds considered to have high levels of opium alkaloids (i.e. poppy seeds from varieties primarily grown for pharmaceutical use) exceed the ARfD in most age groups. For poppy seeds considered to have relatively low concentrations of opium alkaloids (i.e. primarily varieties for food use), some exceedance of the ARfD is also seen at high levels of dietary exposure in most surveys. For noscapine and papaverine, the available data do not allow making a hazard characterisation. However, comparison of the dietary exposure to the recommended therapeutical doses does not suggest a health concern for these alkaloids. For thebaine and oripavine, no risk characterisation was done due to insufficient data. However, for thebaine, limited evidence indicates a higher acute lethality than for morphine and the estimated exposure could present a health risk.

Opioids: Modulators of angiogenesis in wound healing and cancer

Opioids are potent drugs that are widely used to control wound or cancer pain. Increasing evidence suggest that opioids mediate clinically relevant effects that go beyond their classical role as analgesics. Of note, opioids appear to modulate angiogenesis - a process that is critical in wound healing and cancer progression. In this review, we focus on pro- and anti-angiogenic facets of opioids that arise from the activation of individual opioid receptors and the usage of individual concentrations or application routes. We overview the still incompletely elucidated mechanisms of these angiogenic opioid actions. Moreover, we describe plausible opioids effects, which - although not primarily studied in the context of vessel formation - may be related to the opioid-driven processes of angiogenesis. Finally we discuss the use of opioids as an innovative therapeutic avenue for the treatment of chronic wounds and cancer.

Nalmefene attenuates malignant potential in colorectal cancer cell via inhibition of opioid receptor

Morphine is postulated a risk factor in promoting tumor growth and metastasis during the preoperative period, and high glycolysis of tumor cells is proved to accelerate tumor progression. In this study, we investigated whether nalmefene, an opioid receptor inhibitor, could inhibit CT26 colon cancer cell growth through influencing cell glycolysis. CCK8 and transwell migration assays showed that nalmefene inhibited CT26 cells viability and migration in a concentration-dependent manner. Extracellular acidification rate and oxygen consumption rate showed that nalmefene inhibited glycolysis of CT26 cells. Moreover, western blot analysis and quantitative real-time PCR revealed that nalmefene decreased the expressions of enzymes related to glycolysis. Flow cytometry results revealed that intracellular calcium (Ca2+) level was changed by nalmefene, western blot analysis showed that nalmefene decreased calmodulin expression and calcium/calmodulin dependent protein kinases II (CaMK II) phosphorylation, thus inhibiting the serine/threonine kinase (AKT)-glycogen synthase kinase-3β (GSK-3β) pathway. Furthermore, the effects of KN93, an inhibitor of CaMK II, were similar to the effects of nalmefene, and the anti-tumor effect of nalmefene could be counteracted by morphine. In conclusion, the anti-tumor effect of nalmefene may be achieved by inhibiting opioid receptor and down-regulating calmodulin expression and CaMK II phosphorylation, thus inhibiting AKT-GSK-3β pathway and the glycolysis of CT26 cells.

Opioids and cancer: friend or foe?

PURPOSE OF REVIEW

Most cancer patients experience pain and many will require opioids. However, the effects of opioids on cancer progression, metastasis, and recurrence is increasingly being questioned. There is evidence that opioids affect immune system function, angiogenesis, apoptosis, and invasion in a potentially deleterious manner. This review will examine the preclinical and clinical evidence.

RECENT FINDINGS

Recent clinical data have struggled to find robust evidence that opioids promote cancer progression. Although most study has involved morphine, differential effects of other opioids on immune function and cancer are revealing a more complex picture.

SUMMARY

Although there is a biologically plausible story, evidence for the action of opioids on cancer is mixed. Indeed, it may even be that in the chronic setting morphine has a beneficial effect on outcome in certain cancer types. This review critically examines and evaluates the evidence for the action of opioids on the processes involved in cancer progression. In the light of the uncertainty of opioid effect on cancer, any decision making should be tempered by knowing that stress and pain undoubtedly contribute to cancer progression.