GPR84 potently inhibits osteoclastogenesis and alleviates osteolysis in bone metastasis of colorectal cancer

Molecular characterization of GPR84 in domestic cats

G protein-coupled receptor 84 (GPR84) was cloned as an orphan receptor, and medium-chain fatty acids were then revealed as endogenous ligands. GPR84 is expressed in immune cells and is believed to protect liver function from lipotoxicity caused by overeating and high-fat diet intake. This study aimed to present the molecular characterization of GPR84 in domestic cats. The deduced amino acid sequence of the feline GPR84 shows high sequence homology (83-89 %) with the orthologues from other mammalians by cDNA cloning of feline GPR84. Remarkably high mRNA expression was observed in the bone marrow by Q-PCR analysis. The inhibition of intracellular cAMP concentration was observed in cells transfected with feline GPR84 and treated with medium-chain fatty acids. Immunostaining of GPR84 and free fatty acid receptor 2 (FFAR2)/GPR43 in the bone marrow, where high mRNA expression was observed, showed reactions in macrophages and myeloid cells. To clarify whether the receptor formed homo/hetero-merization, GPR84 and FFARs were analyzed using Nano-Luc binary technology and NanoLuc bioluminescence resonance energy transfer technologies, which revealed that GPR84 formed more heteromers with FFAR2 than homomers with each other. In addition, when GPR84 and FFAR2/GPR43 were cotransfected in the cell, their localization on the cell membrane was reduced compared with that when single receptors were transfected. These results indicated that GPR84 is a functional receptor protein that is expressed in cat tissues and may have a protein-protein interaction with FFAR2/GPR43 on the cell membrane.

Beyond boundaries: unraveling innovative approaches to combat bone-metastatic cancers

Evidence demonstrated that bones, liver, and lungs are the most common metastasis sites in some human malignancies, especially in prostate and breast cancers. Bone is the third most frequent target for spreading tumor cells among these organs and tissues. Patients with bone-metastatic cancers face a grim prognosis characterized by short median survival time. Current treatments have proven insufficient, as they can only inhibit metastasis or tumor progression within the bone tissues rather than providing a curative solution. Gaining a more profound comprehension of the interplay between tumor cells and the bone microenvironment (BME) is of utmost importance in tackling this issue. This knowledge will pave the way for developing innovative diagnostic and therapeutic approaches. This review summarizes the mechanisms underlying bone metastasis and discusses the clinical aspects of this pathologic condition. Additionally, it highlights emerging therapeutic interventions aimed at enhancing the quality of life for patients affected by bone-metastatic cancers. By synthesizing current research, this review seeks to shed light on the complexities of bone metastasis and offer insights for future advancements in patient care.

Current and potential treatment of colorectal cancer metastasis to bone

BACKGROUND

Colorectal cancer (CRC) with subsequent bone metastasis is associated with a poor prognosis compared with patients who do not develop bone metastasis. However, metastasis in bone is rare, contrasted with more common locations such as the liver and lungs. As a result, the treatment methods targeting CRC bone lesions are limited. This review aims to compile information regarding current and potential medical and surgical treatment methods for colorectal cancer with specific regard to bone metastasis.

METHODS

A computer-based literature review of animal- and human-based studies was conducted using multiple database searches. Case reports were excluded.

RESULTS

Preliminary findings demonstrate that treatments specifically targeting bone metastasis due to colorectal cancer are categorized by local vs. systemic treatment. The primary goals are the alleviation of skeletal-related events and improvement in quality of life. Current options include: chemotherapy, radiation, monoclonal antibodies, and surgery. Emerging options include intratumoral mellitin, MRgFUS, and bone microenvironment targeting.

CONCLUSION

Treatment of CRC metastasis to bone is necessary to slow down metastatic progression, alleviate symptoms, and improve quality of life. With a possible rise in bone metastasis due to increased overall CRC survival rates, more clinical trials should be performed to address this growing concern.