Somatostatin and opioid receptors do not regulate proliferation or apoptosis of the human multiple myeloma U266 cells

Mu and Kappa opioid receptor immunolabeling indicates the prognosis of oropharyngeal squamous cell carcinoma: A cross-sectional observational study

BACKGROUND

Opioids are the most effective drugs currently available for cancer pain management. The administration of morphine, in addition to its analgesic effect, can alter tumor development.

OBJECTIVE

To characterize the immunoexpression of opioid receptors µ and κ in oropharyngeal squamous cell carcinoma, and correlate it with prognostic factors, proliferation markers, and cell death.

MATERIALS AND METHODS

A retrospective, cross-sectional observational study was carried out with 50 patients diagnosed at Haroldo Juaçaba Hospital. Sociodemographic, clinicopathological, and overall survival data were collected, and excisional biopsies were taken for immunohistochemistry using tissue microarrays for opioid receptors µ and κ, Ki-67, and caspase-3. Immunolabeling was evaluated and correlated with other variables using Mann-Whitney, Kruskal-Wallis, Spearman correlation, log-rank (Mantel-Cox), and Cox regression tests.

RESULTS

Immunoexpression of opioid receptors µ and κ, Ki-67, and caspase-3 was significantly higher in p16+ and p16- primary tumors and lymph node metastases than in surgical resection margins. The overall survival of patients with p16- tumors was 57.53 ± 8.43 months and that of patients with p16+ tumors was slightly higher at 75.92 ± 11.14 months. Multivariate analysis showed that the expression of opioid receptors µ and κ in the nucleus was directly associated with a lower and higher risk of death, respectively.

CONCLUSION

We found increased expression of opioid receptors µ and κ in tumor tissues. The nuclear expression of opioid receptors µ and κ influences overall survival and may be a prognostic factor of oropharyngeal squamous cell carcinoma.

BIBR1532 inhibits proliferation and enhances apoptosis in multiple myeloma cells by reducing telomerase activity

Background

Multiple myeloma (MM) is a rare haematological disorder with few therapeutic options. BIBR1532, a telomerase inhibitor, is widely used in cancer treatment and has promising outcomes. In this study, we investigated the efficacy and mechanism of action of BIBR1532 in MM.

Methods

K562 and MEG-01 cells were cultured with BIBR1532 at different concentrations. After 24 and 48 h, cell survival was analyzed. Next, these cells were cultured with 25 and 50 µM BIBR1532 for 48 h, then, cell proliferation, apoptosis, and the expression of the telomerase activity related markers were tested by 5-Ethynyl-2'-deoxyuridine (EdU) staining, flow cytometric analysis, western blot and quantitative real-time PCR (qRT-PCR), respectively. Expression of Bcl-xL, Bad, Survivin, phosphorylation of PI3K, AKT, mTOR, ERK1/2, and MAPK were tested via western blotting. Further experiments were conducted to evaluate the synergistic effects of BIBR1532 and doxorubicin (Dox) or bortezomib (Bor).

Results

BIBR1532 inhibited K562 and MEG-01 cell survival in a dose- and time-dependent manner. In addition, BIBR1532 hindered cell proliferation while promoting apoptosis, and this effect was enhanced by increasing the BIBR1532 concentration. Moreover, BIBR1532 inhibited TERT and c-MYC expression, PI3K, AKT, mTOR phosphorylation, and facilitated ERK1/2 and MAPK phosphorylation. Additionally, BIBR1532 combined with Dox or Bor showed synergistic effects in MM treatment.

Conclusion

BIBR1532 inhibits proliferation and promotes apoptosis in MM cells by inhibiting telomerase activity. Additionally, BIBR1532 combined with Dox or Bor exhibited synergistic effects, indicating that BIBR1532 may be a novel medicine for the treatment of MM.

Disturbing the Redox Balance Using Buthionine Sulfoximine Radiosensitized Somatostatin Receptor-2 Expressing Pre-Clinical Models to Peptide Receptor Radionuclide Therapy with 177Lu-DOTATATE

Peptide receptor radionuclide therapy with ¹⁷⁷Lu-DOTATATE improves the outcome of patients with somatostatin receptor (SSTR)-expressing neuroendocrine tumours. Nevertheless, stable disease has been the main response pattern observed, with some rare complete responses. Lu-177 exerts about two-thirds of its biological effects via the indirect effects of ionizing radiation that generate reactive oxygen species, eventually leading to oxidative damage and cell death. This provides a rationale for targeting the antioxidant defence system in combination with ¹⁷⁷Lu-DOTATATE. In the present study, the radiosensitizing potential and the safety of depleting glutathione (GSH) levels using buthionine sulfoximine (BSO) during ¹⁷⁷Lu-DOTATATE therapy were assessed in vitro and in vivo using a xenograft mouse model. In vitro, the combination resulted in a synergistic effect in cell lines exhibiting a BSO-mediated GSH decrease. In vivo, BSO neither influenced ¹⁷⁷Lu-DOTATATE biodistribution nor induced liver, kidney or bone marrow toxicity. In terms of efficacy, the combination resulted in reduced tumour growth and metabolic activity. Our results showed that disturbing the cell redox balance using a GSH synthesis inhibitor increased ¹⁷⁷Lu-DOTATATE efficacy without additional toxicity. Targeting the antioxidant defence system opens new safe treatment combination opportunities with ¹⁷⁷Lu-DOTATATE.

Investigating intrinsic radiosensitivity biomarkers to peptide receptor radionuclide therapy with [177Lu]Lu-DOTATATE in a panel of cancer cell lines

INTRODUCTION

[¹⁷⁷Lu]Lu-DOTATATE is an effective systemic targeted radionuclide therapy for somatostatin receptor (SSTR) positive metastatic or inoperable neuroendocrine tumours (NET). However, for a given injected activity, tumour responses are variable. Our aim was to investigate whether SSTR expression/functionality and known characteristics of intrinsic radiosensitivity, namely proliferation rate, glucose metabolism, cell cycle phase, DNA repair and antioxidant defences were predictors of sensitivity to [¹⁷⁷Lu]Lu-DOTATATE in SSTR expressing human cancer cell lines.

METHODS

In six human cancer cell lines and under basal condition, SSTR expression was assessed by qRT-PCR and immunocytochemistry. Its functionality was evaluated by binding/uptake assays with [⁶⁸Ga]Ga- and [¹⁷⁷Lu]Lu-DOTATATE. The radiosensitivity parameters were evaluated as follows: proliferation rate (cell counting), glucose metabolism ([¹⁸F]FDG uptake), antioxidant defences (qRT-PCR, colorimetric assay, flow cytometry), DNA repair (qRT-PCR) and cell cycle (flow cytometry). Effect of [¹⁷⁷Lu]Lu-DOTATATE on cell viability was assessed 3, 7 and 10 days after 4 h incubation with [¹⁷⁷Lu]Lu-DOTATATE using crystal violet.

RESULTS

Based on cell survival at day 10, cell lines were classified into two groups of sensitivity to [¹⁷⁷Lu]Lu-DOTATATE. One group with <20% of survival decrease (-14 to -1%) and one group with >20% of survival decrease (-22 to -33%) compared to the untreated control cell lines. The latter had significantly lower total antioxidant capacity, glutathione (GSH) levels and glucose metabolism (p < 0.05) compared to the first group. SSTR (p = 0.64), proliferation rate (p = 0.74), cell cycle phase (p = 0.55), DNA repair (p > 0.22), combined catalase and GSH peroxidase expression (p = 0.42) and superoxide dismutase (SOD) activity (p = 0.41) were not significantly different between the two groups.

CONCLUSION

Antioxidant defences may be major determinants in [¹⁷⁷Lu]Lu-DOTATATE radiosensitivity.

Inhibition of δ-opioid receptors induces brain glioma cell apoptosis through the mitochondrial and protein kinase C pathways

Brain glioma is a malignant tumor with a high incidence rate and poor prognosis that has become a focus of studies of central nervous system diseases. Previous studies have suggested that δ-opioid receptors may affect the proliferation and apoptosis of numerous types of tumor cells. However, to date, their precise mechanism(s) of action have not been elucidated. The present study aimed to investigate the effects of inhibiting δ-opioid receptors in brain glioma cell proliferation and apoptosis and their relevant molecular mechanisms. Various doses of naltrindole were supplied to treat brain glioma cells using the MTT method to assess the proliferation index. Flow cytometry was used to investigate the changes in cell apoptosis and mitochondrial membrane potential. The expression levels of Bax, Bcl-2, Bcl-xL, cytochrome c, caspase-9, caspase-3 and protein kinase C (PKC) were measured using western blotting. Naltrindole was observed to inhibit brain glioma cell proliferation and promote apoptosis in a dose- and time-dependent manner. Furthermore, the addition of naltrindole lead to changes in the brain glioma cell membrane potential and regulated Bax translocation to the mitochondrial membrane, consequently promoting the release of cytochrome c into the cytoplasm, followed by the activation of caspase-9 and -3, which caused cell apoptosis. In addition, naltrindole was able to regulate the expression levels of the cellular internal phosphorylated PKC proteins, which are closely associated with the inhibition of cell proliferation. In conclusion, the inhibition of δ-opioid receptors may inhibit brain glioma cell proliferation and lead to apoptosis, which is closely associated with the mitochondrial and PKC pathways.

Chronic morphine treatment attenuates cell growth of human BT474 breast cancer cells by rearrangement of the ErbB signalling network

Background

There is increasing evidence that opioid analgesics may interfere with tumour growth. It is currently thought that these effects are mediated by transactivation of receptor tyrosine kinase (RTK)-controlled ERK1/2 and Akt signalling. The growth of many breast cancer cells is dependent on hyperactive ErbB receptor networks and one of the most successful approaches in antineoplastic therapy during the last decade was the development of ErbB-targeted therapies. However, the response rates of single therapies are often poor and resistance mechanisms evolve rapidly. To date there is no information about the ability of opioid analgesics to interfere with the growth of ErbB-driven cancers.

Methods and Principal Findings

Here we demonstrate that ErbB2 overexpressing BT474 human breast cancer cells carry fully functional endogenous µ-opioid receptors. Most interestingly, the acute opioid effects on basal and Heregulin-stimulated ERK1/2 and Akt phosphorylation changed considerably during chronic Morphine treatment. Investigation of the underlying mechanism by the use of protein kinase inhibitors and co-immunoprecipitation studies revealed that chronic Morphine treatment results in rearrangement of the ErbB signalling network leading to dissociation of ERK1/2 from Akt signalling and a switch from ErbB1/ErbB3 to ErbB1/ErbB2-dependent cell growth. In chronically Morphine-treated cells Heregulin-stimulated ERK1/2 signalling is redirected via a newly established PI3K- and metalloproteinase-dependent feedback loop. Together, these alterations result in apoptosis of BT474 cells. A similar switch in Heregulin-stimulated ERK1/2 signalling from an ErbB2-independent to an ErbB2-, PI3K- and metalloproteinase-dependent mechanism was also observed in κ-opioid receptor expressing SKBR3 human mammary adenocarcinoma cells.

Conclusions and Significance

The present data demonstrate that the ErbB receptor network of human breast cancer cells represents a target for chronic Morphine treatment. Rearrangement of ErbB signalling by chronic Morphine may provide a promising strategy to enhance the sensitivity of breast cancer cells to ErbB-directed therapies and to prevent the development of escape mechanisms.

Morphine and tumor growth and metastasis

Morphine is an analgesic widely used to alleviate cancer pain. In addition, the perioperative management of pain in cancer surgery patients most often includes opioids. However, there are reports that these drugs may alter cancer recurrence or metastasis. Several mechanisms have been proposed, such as the modulation of the immune response or cellular pathways that control the survival and migratory behavior of cancer cells. The published literature, however, presents some discrepancies, with reports suggesting that opioids may either promote or prevent the spread of cancer. It is of great importance to determine whether opioids, in particular the most widely used, morphine, may increase the risk of metastasis when used in cancer surgery. This review examines the available data on the effects of morphine which influence cancer metastasis or recurrence, including immunomodulation, tumor cell aggressiveness, and angiogenesis, with special emphasis on recently published clinical and laboratory based studies. We further discuss the parameters that may explain the difference between reports on the effects of morphine on cancer.

Endogenous opiates and behavior: 2009

This paper is the 32nd consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2009 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).