Regulatory T cells: A possible promising approach to cancer recurrence induced by morphine

Chronic Cancer Pain: Opioids within Tumor Microenvironment Affect Neuroinflammation, Tumor and Pain Evolution

Simple Summary

Pain is a worrisome symptom that 60–80% of patients with cancer experience chronically. In the last twenty years, immunological and pain research have shown that cancer pain is attributable to the neuroinflammatory response driven by the cellular and soluble components of the tumor microenvironment, with features similar to that induced in many other painful chronic non-cancer diseases. Neuroinflammation leads to central sensitization and neuroplastic remodeling of the central nervous system with alteration of pain sensitivity (hyperalgesia), responsiveness (behavior), and drive (centralization). Engagement of opioid receptors by both endogenous and exogenous opioids, namely, the cornerstone of pain therapy morphine, results in modulation of pain intensity and quality, in addition to cancer growth and progression. The effects of opioids on the evolution of pain, (relief or immune-mediated hyperalgesia) and cancer (promotion or inhibition), are dual and ambiguous. This ambiguity currently represents a major limitation of long-term opioid therapy, and encourages novel immunotherapeutic strategies.

Abstract

Pain can be a devastating experience for cancer patients, resulting in decreased quality of life. In the last two decades, immunological and pain research have demonstrated that pain persistence is primarily caused by neuroinflammation leading to central sensitization with brain neuroplastic alterations and changes in pain responsiveness (hyperalgesia, and pain behavior). Cancer pain is markedly affected by the tumor microenvironment (TME), a complex ecosystem consisting of different cell types (cancer cells, endothelial and stromal cells, leukocytes, fibroblasts and neurons) that release soluble mediators triggering neuroinflammation. The TME cellular components express opioid receptors (i.e., MOR) that upon engagement by endogenous or exogenous opioids such as morphine, initiate signaling events leading to neuroinflammation. MOR engagement does not only affect pain features and quality, but also influences directly and/or indirectly tumor growth and metastasis. The opioid effects on chronic cancer pain are also clinically characterized by altered opioid responsiveness (tolerance and hyperalgesia), a hallmark of the problematic long-term treatment of non-cancer pain. The significant progress made in understanding the immune-mediated development of chronic pain suggests its exploitation for novel alternative immunotherapeutic approaches.

Effect of Isolated Serum from Breast Cancer Patients with Pectoral Nerves Block on Breast Cancer Cell Line (MDA-MB-231) Apoptosis Index

Background

Breast cancer (BC) is the most frequent cause of cancer death in women. The thoracic pectoral nerve (PECS) block has been described as the gold standard analgesic modality for BC surgery. It has been previously reported that PECS is associated with decreased BC recurrence post-mastectomy. Although several anesthetic drugs and techniques are used in surgical oncology, their effects on the behavior of cancer cells are yet to be known and the key question of whether the anesthetic technique affects cancer outcome remains unresolved.

Objectives

Since anesthetic drugs and techniques and post-operative pain may affect BC recurrence, this study aimed to determine whether the anesthetic choice and technique, PECS II block, affects in vitro apoptosis of the MDA-MB-231 BC cell line.

Methods

Twenty-two female BC patients, 20 to 75-years-old, with the same pathologic grades were included in this study. The patients were randomly divided into two groups. The first group received propofol general anesthesia (PGA) associated with PECS and the second group received standard PGA. Blood was sampled pre and post-operation from all patients. The sera were isolated and then exposed to the MDA-MB-231 human BC cell line. The mean percentage of apoptosis indices was analyzed by flow cytometry using Annexin V-fluorescein isothiocyanate 24 hours after treatment with patients' sera.

Results

A significant decrease was seen in the mean viability percentage of BC cell line in the PECS group, besides a significant increase in the mean percentage of necrosis and late apoptosis indices compared to the control group after exposure to sera collected from patients post-operation. Intra-group analysis of the control group showed that the exposure of the tumoral cell to post-operation sera resulted in a significant increase in the mean percentage of necrosis and late apoptosis index compared to pre-operation sera exposure. In the PECS group, the exposure of the tumoral cell to post-operation sera resulted in a significant increase in the mean percentage of cell viability and late apoptosis index compared to pre-operation sera exposure.

Conclusions

In conclusion, anesthesia and BC surgery may induce apoptosis indices in the MDA-MB-231 human BC cell line. We also found that sera collected from PECS II block patients with BC could induce more apoptosis in the MDA-MB-231 cell line compared to collected sera from systemic analgesia alone after BC surgery.

Exogenous morphine inhibits the growth of human gastric tumor in vivo

Morphine is commonly used to relieve severe pain that is often associated with cancer. Previous studies have found that morphine could affect cancer development; however, this effect is poorly understood. To further clarify the anti-cancer potential of morphine for the development of cancer in vivo, we observed how morphine affects the growth of human gastric tumor in a murine xenografting model and the expression of NF-κB and its downstream target genes (Bcl-2/Bax, cyclind1, and VEGF). The growth of the tumor was evaluated by its growth curves. The mRNA expression levels of NF-κB, Bcl-2/Bax, cyclind1, and VEGF were assessed by semi-quantitative polymerase chain reaction (qPCR). The protein expression of NF-κB, Bcl-2/Bax, cyclind1, and VEGF was detected by immunochemistry staining and western blot. Our data showed that morphine effectively inhibited the tumor growth in the nude mice. Morphine inhibits the expression of NF-κB, Bcl-2, cyclind1, and VEGF while enhancing the expression of Bax in the tumors. Furthermore, the anti-cancer effects of morphine could be reversed by naloxone. The mechanism might be associated with the action of opioid receptors that downregulate the expression of NF-κB leading to the regulation of the downstream target genes (Bcl-2/Bax, cylind1, and VEGF) in the tumors.

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.

Morphine as a suspect of aiding the propagation of cancer cells

Controlling pain in cancer patients is important for several reasons including patient quality of life (QOL). In moderate-to-severe cancer-pain management, opioid analgesics are indispensable. Among these, morphine is the most representative. Unfortunately, many studies have shown that morphine is potentially associated with cancer growth, recurrence, and metastasis. Specifically, in animal as well as in vivo and in vitro studies, morphine has been demonstrated to have possibly positive effects on cancer progression. However, those effects have not yet been confirmed as entirely harmful, for several reasons: the results of animal and laboratory research have not been subjected to clinical trials; there are as yet no well-designed clinical studies, and indeed, some studies have shown that morphine can have negative, suppression effects on tumor growth. This review paper will present some of the data on the potentially positive relationships between morphine and cancer. It should not be forgotten, though, that such relationships remain controversial, and that pain itself promotes cancer progression.

Does Opioid Use Cause Angiogenesis and Metastasis?

Objective

To provide a comprehensive overview of the potential for morphine to lead to angiogenesis and metastasis.

Background

Morphine is often the treatment of choice for severe cancer-related pain. Small studies have been emerging that indicate that opioids may influence angiogenesis and metastasis, but this has not yet been comprehensively synthesized.

Purpose

To highlight morphine's relationship with angiogenesis and metastasis in in vitro models.

Method

A review of the literature was conducted using PubMed (1966 to 2015) and Cochrane Library (1987 to 2015) electronic databases. The search, as well as consultation with experts, yielded 84 articles for initial review, 12 of which met inclusion for review. Possible theories of the underlying etiology of the metastasis and angiogenesis were recorded.

Results

All studies were assessed using the PRISMA checklist.

Conclusion

This systematic review demonstrates that morphine has a potential causal relationship with angiogenesis and metastasis. This is likely due to multiple etiologies, including immunosuppressive, pro-inflammatory, and pro-angiogenetic.

Management of Chronic Pain in Survivors of Adult Cancers: American Society of Clinical Oncology Clinical Practice Guideline

PURPOSE

To provide evidence-based guidance on the optimum management of chronic pain in adult cancer survivors.

METHODS

An ASCO-convened expert panel conducted a systematic literature search of studies investigating chronic pain management in cancer survivors. Outcomes of interest included symptom relief, pain intensity, quality of life, functional outcomes, adverse events, misuse or diversion, and risk assessment or mitigation.

RESULTS

A total of 63 studies met eligibility criteria and compose the evidentiary basis for the recommendations. Studies tended to be heterogeneous in terms of quality, size, and populations. Primary outcomes also varied across the studies, and in most cases, were not directly comparable because of different outcomes, measurements, and instruments used at different time points. Because of a paucity of high-quality evidence, many recommendations are based on expert consensus.

RECOMMENDATIONS

Clinicians should screen for pain at each encounter. Recurrent disease, second malignancy, or late-onset treatment effects in any patient who reports new-onset pain should be evaluated, treated, and monitored. Clinicians should determine the need for other health professionals to provide comprehensive pain management care in patients with complex needs. Systemic nonopioid analgesics and adjuvant analgesics may be prescribed to relieve chronic pain and/or to improve function. Clinicians may prescribe a trial of opioids in carefully selected patients with cancer who do not respond to more conservative management and who continue to experience distress or functional impairment. Risks of adverse effects of opioids should be assessed. Clinicians should clearly understand terminology such as tolerance, dependence, abuse, and addiction as it relates to the use of opioids and should incorporate universal precautions to minimize abuse, addiction, and adverse consequences. Additional information is available at www.asco.org/chronic-pain-guideline and www.asco.org/guidelineswiki.

Dexmedetomidine Inhibits Maturation and Function of Human Cord Blood-Derived Dendritic Cells by Interfering with Synthesis and Secretion of IL-12 and IL-23

Aims

To investigate the effects and underlying mechanism of dexmedetomidine on the cultured human dendritic cells (DCs).

Methods

Human DCs and cytotoxic T lymphocytes (CTLs) were obtained from human cord blood mononuclear cells by density gradient centrifugation. Cultured DCs were divided into three groups: dexmedetomidine group, dexmedetomidine plus yohimbine (dexmedetomidine inhibitor) group and control group. DCs in the three groups were treated with dexmedetomidine, dexmedetomidine plus yohimbine and culture medium, respectively. After washing, the DCs were co-incubated with cultured CTLs. The maturation degree of DCs was evaluated by detecting (1) the ratios of HLA-DR-, CD86-, and CD80-positive cells (flow cytometry), and (2) expression of IL-12 and IL-23 (PCR and Elisa). The function of DCs was evaluated by detecting the proliferation (MTS assay) and cytotoxicity activity (the Elisa of IFN-γ) of CTLs. In addition, in order to explore the mechanisms of dexmedetomidine modulating DCs, α2-adrenergic receptor and its downstream signals in DCs were also detected.

Results

The ratios of HLA-DR-, CD86-, and CD80-positive cells to total cells were similar among the three groups (P>0.05). Compared to the control group, the protein levels of IL-12 and IL-23 in the culture medium and the mRNA levels of IL-12 p35, IL-12 p40 and IL-23 p19 in the DCs all decreased in dexmedetomidine group (P<0.05). In addition, the proliferation of CTLs and the secretion of IFN-γ also decreased in the dexmedetomidine group, compared with the control group (P<0.05). Moreover, these changes induced by dexmedetomidine in the dexmedetomidine group were reversed by α2-adrenergic receptor inhibitor yohimbine in the dexmedetomidine plus yohimbine group. It was also found the decrease of mRNA levels of IL-12 p35, IL-12 p40 and IL-23 p19 in the dexmedetomidine group could be reversed by ERK1/2 or AKT inhibitors.

Conclusion

Dexmedetomidine could negatively modulate human immunity by inhibiting the maturation of DCs and then decreasing the proliferation and cytotoxicity activity of CTLs. The α2-adrenergic receptors and its downstream molecules ERK1/2 and AKT are closely involved in the modulation of dexmedetomidine on DCs.

Management of cancer pain: 1. Wider implications of orthodox analgesics

In this review, the first of two parts, we first provide an overview of the orthodox analgesics used commonly against cancer pain. Then, we examine in more detail the emerging evidence for the potential impact of analgesic use on cancer risk and disease progression. Increasing findings suggest that long-term use of nonsteroidal anti-inflammatory drugs, particularly aspirin, may reduce cancer occurrence. However, acetaminophen may raise the risk of some hematological malignancies. Drugs acting upon receptors of gamma-aminobutyric acid (GABA) and GABA “mimetics” (eg, gabapentin) appear generally safe for cancer patients, but there is some evidence of potential carcinogenicity. Some barbiturates appear to slightly raise cancer risks and can affect cancer cell behavior in vitro. For cannabis, studies suggest an increased risk of squamous cell carcinoma of the tongue, larynx, and possibly lung. Morphine may stimulate human microvascular endothelial cell proliferation and angiogenesis; it is not clear whether this might cause harm or produce benefit. The opioid, fentanyl, may promote growth in some tumor cell lines. Opium itself is an emerging risk factor for gastric adenocarcinoma and possibly cancers of the esophagus, bladder, larynx, and lung. It is concluded that analgesics currently prescribed for cancer pain can significantly affect the cancer process itself. More futuristically, several ion channels are being targeted with novel analgesics, but many of these are also involved in primary and/or secondary tumorigenesis. Further studies are needed to elucidate possible cellular and molecular effects of orthodox analgesics and their possible long-term impact, both positive and negative, and thus enable the best possible clinical gain for cancer patients.