The kappa opioid receptor may be a potential tumor suppressor by regulating angiogenesis in breast cancer

Impact of opioids and mu-opioid receptors on oncologic metastasis

Opioids are the most effective and widely used treatments for acute and chronic pain in patients with cancer. This review focuses on the impact of opioids and mu-opioid receptors (MORs) on the stages of oncologic metastasis. Studies have shown that opioids can facilitate tumor progression and are related to a poor prognosis in patients with cancer. As the primary receptor for opioids, MORs play a significant role in regulating malignant tumor transformation and are involved in processes, such as proliferation, angiogenesis, epithelial-mesenchymal transition (EMT), circulating tumor cells (CTCs) and the tumor microenvironment (TME). While clinical trials have investigated the relationship between opioids and patient prognosis, further research is needed to clarify the relationship between opioids, MORs and metastasis.

Synthesis and Antiproliferative Activity against Cancer Cells of Indole-Aryl-Amide Derivatives

Indoles constitute a large family of heterocyclic compounds widely occurring in nature which are present in a number of bioactive natural and synthetic compounds, including anticancer agents or atypical opioid agonists. As a result, exponential increases in the development of novel methods for the synthesis of indole-containing compounds have been reported in the literature. A series of indole-aryl amide derivatives 1-7 containing tryptamine or an indolylacetic acid nucleus were designed, synthesized, and evaluated as opioid ligands. These new indole derivatives showed negligible to very low affinity for μ- and δ-opioid receptor (OR). On the other hand, compounds 2, 5 and 7 showed Ki values in the low μM range for κ-OR. Since indoles are well known for their anticancer potential, their effect against a panel of tumor cell lines was tested. The target compounds were evaluated for their in vitro cytotoxicity in HT29, HeLa, IGROV-1, MCF7, PC-3, and Jurkat J6 cells. Some of the synthesized compounds showed good activity against the selected tumor cell lines, with the exception of IGROV1. In particular, compound 5 showed a noteworthy selectivity towards HT29 cells, a malignant colonic cell line, without affecting healthy human intestinal cells. Further studies revealed that 5 caused the cell cycle arrest in the G1 phase and promoted apoptosis in HT29 cells.

Opioids in cancer: The κ‑opioid receptor (Review)

The κ‑opioid receptor (KOR) is one of the primary receptors of opioids and serves a vital role in the regulation of pain, anesthesia, addiction and other pathological and physiological processes. KOR is associated with several types of cancer and may influence cancer progression. It has been proposed that KOR may represent a new tumor molecular marker and provide a novel basis for molecular targeted therapies for cancer. However, the association between KOR and cancer remains to be explored comprehensively. The present review introduces KOR and its association with different types of cancer. Improved understanding of KOR may facilitate development of novel antitumor therapies.

Perioperative pain, analgesics and cancer-related outcomes: where do we stand?

Cancer-related pain is one of the most common and debilitating symptoms among cancer patients. Undertreated cancer-related pain interferes with daily activities and increases morbidity and mortality. While opioids continue to play an essential role in treating moderate to severe cancer-related pain, they are associated with many adverse effects including misuse. While preclinical and retrospective studies have shown a negative association between opioid use and cancer outcomes, randomized control trials demonstrate that opioid use does not influence cancer recurrence. Additionally, analgesics and adjuvants used for perioperatively or chronic pain control are unlikely to improve oncological outcomes. This article focuses on the pharmacological management of cancer-related pain and offers an overview regarding the use of these medications perioperatively and the cancer outcomes.