Activity of Melatonin Against Gastric Cancer Growth in a Chick Embryo Tumor Xenograft Model

Melatonin blunted the angiogenic activity in 3D colon cancer tumoroids by the reduction of endocan

BACKGROUND

Complexity and heterogeneity of the tumor niche are closely associated with the failure of therapeutic protocols. Unfortunately, most data have been obtained from conventional 2D culture systems which are not completely comparable to in vivo microenvironments. Reconstructed 3D cultures composed of multiple cells are valid cell-based tumor models to recapitulate in vivo-like interaction between the cancer cells and stromal cells and the oncostatic properties of therapeutics. Here, we aimed to assess the tumoricidal properties of melatonin on close-to-real colon cancer tumoroids in in vitro conditions.

METHODS

Using the hanging drop method, colon cancer tumoroids composed of three cell lines, including adenocarcinoma HT-29 cells, fibroblasts (HFFF2), and endothelial cells (HUVECs) at a ratio of 2: 1: 1, respectively were developed using 2.5% methylcellulose. Tumoroids were exposed to different concentrations of melatonin, from 0.005 to 0.8 mM and 4 to 10 mM, for 48 h. The survival rate was measured by MTT and LDH leakage assays. Protein levels of endocan and VEGF were assessed using western blotting. Using histological examination (H & E) staining, the integrity of cells within the tumoroid parenchyma was monitored.

RESULTS

Despite the reduction of viability rate in lower doses, the structure of tumoroids remained unchanged. In contrast, treatment of tumoroids with higher doses of melatonin, 4 and 10 mM, led to disaggregation of cells and reduction of tumoroid diameter compared to the non-treated control tumoroids (p < 0.05). By increasing melatonin concentration from 4 to 10 mM, the number of necrotic cells increased. Data showed the significant suppression of endocan in melatonin-treated tumoroids related to the non-treated controls (p < 0.05). According to our data, melatonin in higher doses did not alter protein levels of VEGF (p > 0.05).

CONCLUSIONS

Melatonin can exert its tumoricidal properties on colon cancer tumoroids via the reduction of tumor cell viability and inhibition of the specific pro-angiogenesis factor.

Melatonin inhibited the progression of gastric cancer induced by Bisphenol S via regulating the estrogen receptor 1

In recent years, Bisphenol S (BPS) has increasingly been used as an alternative to Bisphenol A (BPA) in food, paper, and personal care products. It is imperative to clarify the relationship between BPS and tumors in order to treat and prevent diseases. This study discovered a new method for predicting tumor correlations between BPS interactive genes. According to analyses conducted by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes, interactive genes were primarily found in gastric cancer. Based on gene-targeted prediction and molecular docking, BPS appears to exert potential gastric cancer-causing effects through estrogen receptor 1 (ESR1). In addition, gastric cancer patients' prognosis could be accurately predicted by a bisphenol-based prognostic prediction model. Subsequently, the proliferation and migration abilities of gastric cancer cells were further demonstrated to be significantly enhanced by BPS. Similarly, molecular docking analysis revealed that melatonin is also highly correlated with gastric cancer and BPS. In cell proliferation and migration assays, melatonin and BPS exposure inhibited the invasion abilities of gastric cancer cells compared to BPS-exposure. Our research provided a new direction for the exploration the correlation between cancer and environmental toxicity.

Use of Melatonin in Cancer Treatment: Where Are We?

Cancer represents a large group of diseases accounting for nearly 10 million deaths each year. Various treatment strategies, including surgical resection combined with chemotherapy, radiotherapy, and immunotherapy, have been applied for cancer treatment. However, the outcomes remain largely unsatisfying. Melatonin, as an endogenous hormone, is associated with the circadian rhythm moderation. Many physiological functions of melatonin besides sleep–wake cycle control have been identified, such as antioxidant, immunomodulation, and anti-inflammation. In recent years, an increasing number of studies have described the anticancer effects of melatonin. This has drawn our attention to the potential usage of melatonin for cancer treatment in the clinical setting, although huge obstacles still exist before its wide clinical administration is accepted. The exact mechanisms behind its anticancer effects remain unclear, and the specific characters impede its in vivo investigation. In this review, we will summarize the latest advances in melatonin studies, including its chemical properties, the possible mechanisms for its anticancer effects, and the ongoing clinical trials. Importantly, challenges for the clinical application of melatonin will be discussed, accompanied with our perspectives on its future development. Finally, obstacles and perspectives of using melatonin for cancer treatment will be proposed. The present article will provide a comprehensive foundation for applying melatonin as a preventive and therapeutic agent for cancer treatment.