Systematic optimization and evaluation of culture conditions for the construction of circulating tumor cell clusters using breast cancer cell lines.

BACKGROUND: Circulating tumor cell (CTC) clusters play a critical role in carcinoma metastasis. However, the rarity of CTC clusters and the limitations of capture techniques have retarded the research progress. In vitro CTC clusters model can help to further understand the biological properties of CTC clusters and their clinical significance. Therefore, it is necessary to establish reliable in vitro methodological models to form CTC clusters whose biological characteristics are very similar to clinical CTC clusters. METHODS: The assays of immunofluorescence, transmission electron microscopy, EdU incorporation, cell adhension and microfluidic chips were used. The experimental metastasis model in mice was used. RESULTS: We systematically optimized the culture methods to form in vitro CTC clusters model, and more importantly, evaluated it with reference to the biological capabilities of reported clinical CTC clusters. In vitro CTC clusters exhibited a high degree of similarity to the reported pathological characteristics of CTC clusters isolated from patients at different stages of tumor metastasis, including the appearance morphology, size, adhesive and tight junctions-associated proteins, and other indicators of CTC clusters. Furthermore, in vivo experiments also demonstrated that the CTC clusters had an enhanced ability to grow and metastasize compared to single CTC. CONCLUSIONS: The study provides a reliable model to help to obtain comparatively stable and qualified CTC clusters in vitro, propelling the studies on tumor metastasis.

Cryptotanshinone inhibits PFK-mediated aerobic glycolysis by activating AMPK pathway leading to blockade of cutaneous melanoma.

BACKGROUND: Cutaneous melanoma is a kind of skin malignancy with low morbidity but high mortality. Cryptotanshinone (CPT), an important component of salvia miltiorrhiza has potent anti-tumor activity and also indicates therapeutic effect on dermatosis. So we thought that CPT maybe a potential agent for therapy of cutaneous melanoma. METHODS: B16F10 and A375 melanoma cells were used for in vitro assay. Tumor graft models were made in C57BL/6N and BALB/c nude mice for in vivo assay. Seahorse XF Glycolysis Stress Test Kit was used to detect extracellular acidification rate and oxygen consumption rate. Si-RNAs were used for knocking down adenosine monophosphate-activated protein kinase (AMPK) expression in melanoma cells. RESULTS: CPT could inhibit the proliferation of melanoma cells. Meanwhile, CPT changed the glucose metabolism and inhibited phosphofructokinase (PFK)-mediated glycolysis in melanoma cells to a certain extent. Importantly, CPT activated AMPK and inhibited the expression of hypoxia inducible factor 1α (HIF-1α). Both AMPK inhibitor and silencing AMPK could partially reverse CPT's effect on cell proliferation, cell apoptosis and glycolysis. Finally, in vivo experimental data demonstrated that CPT blocked the growth of melanoma, in which was dependent on the glycolysis-mediated cell proliferation. CONCLUSIONS: CPT activated AMPK and then inhibited PFK-mediated aerobic glycolysis leading to inhibition of growth of cutaneous melanoma. CPT should be a promising anti-melanoma agent for clinical melanoma therapy.