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Gene & Protein in Disease MOR in cancer

Figure 3. Signaling pathways related to the effect of MOR on tumors. The effect of morphine on receptors can affect tumor progression, apoptosis,
metastasis, angiogenesis, and immunity through MAPK/Erk and other pathways. Bcl-2: B-cell lymphoma 2; Bim: Bcl-2 interacting mediator of cell
death; COX-2: Cyclooxygenase-2; ECM: Extracellular matrix; HIF-1: Hypoxia-inducible factor 1; ICAM-1: Intercellular adhesion molecule 1; JNK: c-Jun
N-terminal kinase; KOR: Kappa (κ)-opioid receptor; MAPK: Mitogen-activated protein kinase; MMPs: Matrix metalloproteinases; MOR: Mu (µ)-opioid
receptor; NO: Nitric oxide; PGE : Prostaglandin E2; ROS: Reactive oxygen species; uPA: Urokinase plasminogen activator; VEGF: Vascular endothelial
2
growth factor.

of patients and is not conducive to the rehabilitation 3.1. Tumor proliferation and progression
of cancer patients. An effective control of cancer pain MOR is expressed in various cancers, such as HCC, CRC,
during the perioperative period will significantly BC, and prostate cancer (PC) [81,82] . Opioid chemicals could
improve the prognosis of patients . At present, narcotic affect tumorigenesis and development following MOR
[78]
analgesics are mostly used in clinical treatment. These activation . Zhang et al. demonstrated that high MOR
[55]
[83]
drugs can effectively relieve the pain of cancer patients expression may be associated with poor prognosis in
and significantly improve their anxiety . Opioids patients with lung squamous cell carcinoma (LSCC). Zylla
[79]
bind to opioid receptors, giving rise to the effects of et al. found a similar result suggesting that high MOR
[84]
MOR activation. The tumor microenvironment plays expression and higher opioids requirement are associated
an important role in tumorigenesis, and there is ample with shorter progression-free survival (PFS) and overall
evidence showing the detection of MOR in cancer survival (OS) in patients with metastatic PC.
cells, immune cells, and endothelial cells in the tumor The occurrence and development of cancer are
microenvironment in addition to neuronal cells . The related to the abnormal activation of several intracellular
[80]
binding of endogenous and exogenous opioids to MOR on signaling pathways. In NSCLC, the overexpression of
the cell surface can affect tumor development through a MOR increases protein kinase B (AKT) and mammalian
variety of mechanisms, having a dual role (Table 1) [18,47,72] . target of rapamycin (mTOR) activation, which promotes
MOR has attracted the interest of many researchers, and tumor proliferation . Similarly, Liu et al. demonstrated
[85]
[86]
there are now a variety of new immunotherapies related that morphine could promote the growth of H460 cells
to MOR. MOR may become a novel molecular marker of in vitro and in vivo, increase Rous sarcoma oncogene
tumor therapy and a new therapeutic target. cellular homolog (Src) phosphorylation, and activate the

Volume 2 Issue 2 (2023) 5 https://doi.org/10.36922/gpd.282