Mutual impact of adipocytes and colorectal cancer cells growing in co-culture conditions.

BACKGROUND: Colorectal cancer (CRC) is the third most common malignancy worldwide. CRC cells are situated in an adipocyte-rich microenvironment, which leads to interactions between adipocytes and CRC cells. Upon exposure to cancer cells, adipocytes transform into cancer-associated adipocytes (CAAs), and as a result, they gain features that promote tumor progression. The aim of this research was to shed more light on the detailed role of interactions between adipocytes and CRC cells associated with cancer progression in the context of these alterations. METHODS: To implement adipocyte-CRC cell interaction, a co-culture model was applied. The analyses mainly focused on the metabolic modifications within CAAs and CRC cells, as well as the proliferation and migration potential of CRC cells. The impact of CRC on adipocytes was investigated by qRT-PCR analysis and Oil Red O staining. Proliferation and migration of CRC cells upon co-culture were tested with videomicroscopy, XTT, and a wound healing assay. Metabolic changes within CAAs and CRC cells were investigated based on lipid droplet formation, cell cycle analysis, gene and protein expression by qRT-PCR, and western blotting techniques. RESULTS: CRC cells induced reprogramming of adipocytes into CAAs, which was connected with downregulation of lipid droplet formation in CAAs and alteration in adipocyte features. CAAs showed decreased metabolism-related gene expression, phosphorylation of Akt, ERK kinases, STAT3, and lactate secretion in comparison to the control. CAAs also promoted the migration, proliferation, and lipid droplet accumulation of CRC cells. After co-culturing with adipocytes, there was a shift to the G2/M phase of the cell cycle according to the differences in cyclin expression. CONCLUSION: There are complex bidirectional interactions between adipocytes and CRC cells that may be connected with the induction of CRC cell progression. Video Abstract.

Melanoma Progression under Obesity: Focus on Adipokines.

Obesity is a growing problem in the world and is one of the risk factors of various cancers. Among these cancers is melanoma, which accounts for the majority of skin tumor deaths. Current studies are looking for a correlation between obesity and melanoma. They suspect that a potential cause of its development is connected to the biology of adipokines, active molecules secreted by adipose tissue. Under physiological conditions, adipokines control many processes, including lipid and glucose homeostasis, insulin sensitivity, angiogenesis, and inflammations. However, when there is an increased amount of fat in the body, their secretion is dysregulated. This article reviews the current knowledge of the effect of adipokines on melanoma growth. This work focuses on the molecular pathways by which adipose tissue secreted molecules modify the angiogenesis, migration, invasion, proliferation, and death of melanoma cells. We also discuss the role of these factors as markers of incidence, metastasis, and melanoma patient survival. Understanding the functions of adipokines will lead to knowledge of whether and how obesity promotes melanoma growth. Further studies may contribute to the innovations of therapies and the use of adipokines as predictive and/or prognostic biomarkers.

The Role of Apelin and Apelin Receptor Expression in Migration and Invasiveness of Colon Cancer Cells.

BACKGROUND/AIM: Colon cancer is the second deadliest malignancy for human. Its correlation with obesity has led to an increasing number of studies focusing on the role of adipokines in colon cancer development. Apelin, which belongs to the family of adipokines, affects several pathological processes, including heart diseases, obesity and carcinogenesis. In this study, we examined the importance of apelin and apelin receptor (APJ) during motility regulation of colon cancer cells. MATERIALS AND METHODS: Colon cancer cells with overexpression of apelin receptor, as well as cells with down-regulation of apelin were used in this study. Migration and invasion ability was tested using Transwell® filters. The proteolytic activity was analyzed with fluorescent-substrate degradation assay and gelatin zymography. We also used confocal microscopy to examine migratory protrusion formation and the localization of MT1-MMP. The levels of AKT and ERK kinases were evaluated using Western blotting assay. RESULTS: Overexpression of APJ receptor resulted in increased migration and invasion abilities through stimulation of migratory protrusion formation and proteolytic activity. These processes were mediated by PI3K/AKT and MAPK signaling pathways. Opposite effect was obtained when the level of apelin was down-regulated. CONCLUSION: The level of apelin and its receptor is strictly connected with regulation of migration and invasion of colon cancer cells. Therefore, apelinergic system seems to be a promising target for anti-cancer therapy.