Table 1.
Preclinical studies assessing the effect on PAMORAs on cancer-related outcomes
| Title: | Participants: | Drugs, dosages and treatment period: | Available outcome: |
|---|---|---|---|
| The novel role of the mu-opioid receptor in lung cancer progression: a laboratory investigation [18]. |
Human NSCLC cell lines H522, H1703, H1993, SW1573, H1437, H358, control BEAS-2B, and mouse LLC cells were obtained from ATCC (Walkersville, MD) C57BL/6 and MOR knockout mice. All mice were 8- to 12-week-old females obtained from Jackson Laboratories (Bar Harbor, ME) |
MNTX 0, 10, or 100 nM or MOR shRNA. Morphine and DAMGO |
MOR agonists (morphine and DAMGO) increased LLC cell growth in vitro. MNTX or silencing MOR expression inhibited LLC invasion and anchor-independent growth. Injection of MOR-silenced LLC leads to a reduction in mouse lung metastasis. MOR knockout mice do not develop significant tumors when injected with LLC compared to wild-type controls. Continuous infusion of MNTX attenuates primary LLC tumor growth and reduces lung metastasis |
|
Nalmefene attenuates malignant potential in colorectal cancer cell via inhibition of opioid receptor [33]. |
Murine CT26 colon cancer cells | Nalmefene was administered to cells in a concentration gradient (N1: 0.625 μg/l, N2: 0.25 μg/l, N3: 1 μg/l, and N4: 10 μg/l) for 10 h | Nalmefene inhibited CT26 cell viability and migration in a concentration-dependent manner, also inhibited glycolysis of CT26 cells. The antitumor effect can be achieved through opioid receptor inhibition and downregulation of calmodulin expression and CaMK II phosphorylation, thus inhibiting the AKT-GSK-3β pathway and CT26 cell glycolysis |
| Low doses of methylnaltrexone inhibits head and neck squamous cell carcinoma growth in vitro and in vivo by acting on the mu-opioid receptor [34]. |
Human HNSCC cell lines: FaDu (from the American Type Culture Collection), MDA686Tu and UMSCC47 (from the laboratory of Dr. Jeffrey N. Myers, The University of Texas M.D. Anderson Cancer Centre) Six- to seven-week-old male athymic nu/nu mice (C57BL/6) were purchased from the Envigo Harlan Laboratories |
DAMGO: 10 nM, 100 nM and 1 μM MNTX: 1 nM, 10 nM, 100 nM and 1 μM for 24,48 and 72 h MNTX 1,10 and 100 μg/kg/day or placebo (0.9% saline solution) were randomly assigned to each mouse |
FaDu and MDA686Tu cell lines express MOR and UMSCC47 not express the receptor. Activation of the receptor with DAMGO caused a significant reduction in cAMP levels in FaDu cells. Knockdown of MOR inhibited in vitro aggressive cell behaviors on FaDu and MDA686Tu cells. MNTX strongly inhibited the proliferation, clonogenic activity, invasion and migration of FaDu and MDA686Tu cells but has no effect on UMSCC47 cells. In vivo MNTX suppresses tumor growth in HNSCC cell tumor-bearing mice |
| Low-dose naltrexone suppresses ovarian cancer and exhibits enhanced inhibition in combination with cisplatin [38]. |
The human ovarian cancer cell line SKOV-334 was obtained from The American Type Culture Collection (Manassas,VA, USA) Four-week-old athymic nu/nu female mice, purchased from the Charles River Laboratory (Wilmington, MA, USA), |
NTX (1025 mol/L), taxol (1029 or 10,210 mol/L), cisplatin (0.01 or 0.001 mg/mL), NTX (1025 mol/L) and taxol (1029 or 10,210 mol/L), NTX (1025 mol/L) and cisplatin (0.01 or 0.001 mg/mL), or an equivalent volume of sterile water | Reduced DNA synthesis and cell proliferation. Enhanced anticancer action. Tumor progression in a non-toxic fashion by reducing DNA synthesis and angiogenesis. Upregulated expression of the OGF and OGFr |
| The opioid growth factor (OGF) and low-dose naltrexone (LDN) suppress human ovarian cancer progression in mice [39]. | Female nude mice were transplanted intraperitoneally with SKOV-3 human ovarian cancer cells | OGF (10 mg/kg), LDN (0.1 mg/kg), or an equivalent volume of vehicle (saline). 40 days of treatment | OGF and LDN markedly reduced ovarian tumor burden (tumor nodule number and weight). The mechanism of action was targeted to an inhibition of tumor cell proliferation and angiogenesis; no changes in cell survival were noted |
| Beta 2 Adrenergic Receptor Antagonist Propranolol and Opioidergic Receptor Antagonist Naltrexone Produce Synergistic Effects on Breast Cancer Growth Prevention by Acting on Cancer Cells and Immune Environment in a Preclinical Model of Breast Cancer [40]. |
Human breast cancer cells MDA-MB-231 (RRID:CVCL_0062), MDA-MB-468 (RRID: CVCL_0419), and T47D (RRID:CVCL_0553) were obtained from American Type Culture Collection (ATCC; Rockville, MD, USA), and MDA-MB-231/Luc-GFP cells were purchased from GenTarget Inc T-cell-deficient, athymic nude (Crl:NIH-Foxn1rnu) female rats aged 21–28 days old were purchased from Charles River (Portage, MI, USA) |
PRO and NTX alone or in combination with increasing concentrations (0.001 μM to 200 μM) for 24, 48, and 72 h | Inhibited the cell growth and progression of breast cancer cells in vitro in cultures, and in vivo in rat xenografts |
| Synergistic effects of methylnaltrexone with 5-fluorouracil and bevacizumab on inhibition of vascular endothelial growth factor-induced angiogenesis [41]. | HPMVEC |
MNTX, 5-FU, 10 nM MNTX + 5-FU, 100 nM MNTX + 5-FU, bevacizumab, 10 ng/mL MNTX + Bevacizumab, 50 ng/mL MNTX + Bevacizumab, Naltrexone, 10 nM Naltrexone + 5-FU, 50 nM Naltrexone + 5-FU, 10 ng/ml Naltrexone + Bevacizumab, 50 ng/ml Naltrexone + Bevacizumab |
MNTX exerts a synergistic effect with 5-FU and bevacizumab on inhibition of VEGF-induced human pulmonary microvascular EC proliferation and migration. These synergistic effects were not observed with naltrexone |
| Methylnaltrexone, a Peripherally Acting Opioid Receptor Antagonist, Enhances Tumoricidal Effects of 5-FU on Human Carcinoma Cells [44]. | The SW-480 colorectal cancer cells (Leibovitz’s L-15), MCF-7 breast cancer cells (RPMI-1640) and non-small cell lung cancer cells (DMEM) were obtained from the American Type Culture Collection (ATCC, Manassas, VA, USA) |
5-FU 10 μM alone, 5-FU 10 μM plus MNTX 0.01 or 0.1 or 1.0 μM. MNTX alone (0.01, 0.1 and 1.0 μM) |
MNTX enhanced the actions of 5-FU. MNTX alone also showed antiproliferative activity in all three cell lines. MNTX increased cell number in the G1 phase and decreased cyclin A expression |
| Low-dose naltrexone inhibits colorectal cancer progression and promotes T apoptosis by increasing M1-type macrophages and activating the Bax/Bcl-2/caspase-3/PARP pathway [45]. |
The human colon cancer cell lines SW480 and HCT116 were obtained from the Cell Bank of the Chinese Academy of Sciences. Normal human colon cells (NCM460 cells, Cell Bank, Chinese Academy of Sciences) were used as controls Female BALB/c nude mice (4–6 weeks old) were purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. (Beijing, China) |
Cells were incubated with 0.25, 0.5, 1, 1.5, and 2 mg/mL of LDN (dissolved in RPMI 1640 prior to addition) for 24, 48, and 72 h 2 groups (5 mice in each group), including the LDN treatment group (intraperitoneal (i.p.) 5 mg/kg/2 days LDN) and normal saline (NS) group |
Tumor size was measured using a caliper. Tumor volume was calculated according to the following formula: volume (mm3) = (length × width2)/2 |
| Low-dose naltrexone inhibits the epithelial-mesenchymal transition of cervical cancer cells in vitro and effects indirectly on tumor-associated macrophages in vivo [46]. |
Hela, Siha, C33A and Caski human cervical cancer cell lines were purchased from the Cell Bank of the Chinese Academy of Sciences ALB/C nude mice (4–6 weeks old) were purchased from Charles River (Beijing, China) |
LDN was dissolved in DMEM to 0.5, 1.5, 2, 3, and 5 mg/mL, and the culture was continued for 24, 48, and 72 h The mice were randomly divided into four groups with five animals in each group, including the control group, the 0.5 mg/kg group, the 5 mg/kg group, and the 10 mg/kg group based on the concentrations of LDN administered to the mice every day |
Suppressed the proliferation, migration and invasion abilities and promote apoptosis in Hela cells Inhibit cervical cancer progression in nude mice. Reduced the number of TAMs, mainly M2 macrophages, and decreased expression of anti-inflammatory factor IL-10 in the serum of nude mice |
| Low-dose naltrexone plays antineoplastic role in cervical cancer progression through suppressing PI3K/AKT/mTOR pathway [47]. |
Human cervical cancer cell lines Hela and Siha (TCHu187 and TCHu113) were purchased from the Cell Bank of the Chinese Academy of Sciences 4 × 106 Hela cells (in 0.1 ml solution) were injected into BABL/c nude mice. The nude mice experiments were performed in four independent groups |
For treatment with LDN, medium containing 1.24 (Hela) or 1.83 (Siha) mg/mL LDN (Amquar Bio Co., Ltd, USA) was added Different dose of LDN were intraperitoneally injected as 0.5 mg/kg, 5 mg/kg, 10 mg/kg |
Upregulate the expression of OGFr. Suppress the abilities of colony formation, migration and invasion in cervical cancer cells. Inhibit cervical cancer progression in mice model. Indirectly reduced the expressions of PI3K, pAKT and mTOR in vitro and in vivo |
| Peripheral Opioid Antagonist Enhances the Effect of Anti-Tumor Drug by Blocking a Cell Growth-Suppressive Pathway In Vivo [48]. |
Gastric cancer tissues and patient’s ascites was provided by the National Cancer Center Hospital. Different human gastric cancer cell lines (HSC-60, 60As6, HSC-39, HSC-42, HSC-43, HSC-44, 44As3, HSC-58, 58As1, 58As9, HSC-59, SNU-16, KATOIII, MKN45, TMK-1, OKAJIMA, PANC-1) and mouse fibroblast cell line (NIH3T3) were used Six-week-old female C.B17/Icr-scid mice were purchased from CLEA Japan (Tokyo, Japan) |
[Met5]-enkephalin (OGF) was purchased from Wako (Tokyo, Japan) (10−4 M). Methylnaltrexone (MNTX) was provided from Drs. H. Nagase & T. Suzuki, (10–6 and 10−5 M). OGF and MNTX were dissolved in sterile water or saline (10−6 M). Docetaxel (Doc) was purchased from Aventis Pharma Co., Ltd. (Tokyo, Japan) (10−9 M). Combination of Doc + MNTX (10−6 M) | Doc + MNTX significantly prolongs survival, alleviates abdominal pain, and diminishes Doc-resistant spheroids on the peritoneal membrane in model mice |
| Modulation of the opioid growth factor ([Met(5)]-enkephalin)-opioid growth factor receptor axis: novel therapies for squamous cell carcinoma of the head and neck [49]. | Nude mice with visible human SCCHN SCC-1 tumors |
Exogenous OGF 10 mg/kg, OGF either once a week (1x/week OGF), 3 times weekly (Monday, Wednesday, Friday) (3x/week OGF), or daily (daily OGF) Imiquimod (5%, Aldara Cream, 3 M, St. Paul, MN) once weekly (1x/week) or 3 times weekly (Monday, Wednesday, Friday; 3x/week) LDN 0.1 mg/kg naltrexone once a week (1x/week LDN), 3 times weekly (Monday, Wednesday, Friday) (3x/week LDN), or daily (daily LDN) |
OGF and LDN increased the latency from visible to measurable tumors up to 1.6-fold. OGF, LDN, and imiquimod treatment markedly reduced tumor volume and weight, and decreased DNA synthesis in tumors |
| Opioid antagonists inhibit the growth of metastatic murine neuroblastoma [50]. | S2OY neuroblastoma (NB) in A/Jax mice | Daily injections of 0.1 mg/kg NTX | 69% tumor take, 70% delay in time prior to tumor appearance, and a 60% increase in median survival time. The pattern and incidence of metastases of NTX and control mice were similar |
| Successive treatment with naltrexone induces epithelial–mesenchymal transition and facilitates the malignant biological behaviors of bladder cancer cells [51]. | The T24 human bladder cancer cell line and MB49 mouse bladder cancer cell line were obtained from the FuHeng Cell Center (Shanghai, China) | Different concentrations (1, 10, and 100 μM) of naltrexone (Aladdin, Shanghai, China) were added to the medium for incubation for 24 h | Successive treatment with naltrexone may be favorable for the progression of bladder tumors by activating the PI3K/AKT signaling pathway and inducing EMT |
PAMORAs: Peripheral antagonist of mu-opioid receptor; NSCLC: non-small cell lung cancer; DAMGO: D-Ala(2), N-Me-Phe(4), Gly(5)-ol-enkephalin; cAMP: cyclic adenosine monophosphate; HNSCC: head and neck squamous cell carcinoma; VEGF: vascular endothelial growth factor; HPMVEC: Human pulmonary microvascular endothelial cell; EC: endothelial cell; mTOR: mammalian target of rapamycin; LPS: Lipopolysaccharide; SCCHN: squamous cell carcinoma of the head and neck; MNTX: Methylnaltrexone; 5-FU: 5-fluorouracil; mTOR: mammalian target of rapamycin; CaMK II: calcium/calmodulin dependent protein kinases II; AKT-GSK-3β: serine/threonine kinase (AKT)-glycogen synthase kinase-3β (GSK-3β); PRO: propranolol; NTX: naltrexone; LDN: low-dose naltrexone; DMEM: Dulbecco’s modified Eagle’s medium; TAMs: tumor-associated macrophages; OGF: opioid growth factor; OGFr: opioid growth factor receptor; LLC: Lewis lung carcinoma; Doc: docetaxel; EMT: epithelial-mesenchymal transition