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Tumor-specific microenvironment contributes to the perifosine resistance in 3D colorectal cancer (CRC) models

Název česky Nádorově specifické mikroprostředí přispívá k rezistenci 3D modelů nádorů tlustého střeva vůči perifosinu


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Popis Nowadays, 95% of anti-cancer drugs in clinical trials fail due to inefficacy and toxicity despite promising results of preclinical studies on 2D cell models. Tumor tissue organization and tumor-specific environment are important factors influencing real drug efficacy. Particularly acidosis and hypoxia can significantly affect the performance of the drug in vivo. Moreover, colorectal tumors can be exposed to a large variety of intraluminal pH (5.9-9.2) depending on their localization in the intestinal tract. In our study, we tested the cytotoxic effect of the perifosine, synthetic alkyl phospholipid, suggested for the treatment of colorectal cancer, to spheroids derived from HT-29 and HCT-116 cells. The spheroids were cultivated under the conditions of external tumor pH between 6.4-8.2 using either lactic acid (20 mM) or sodium bicarbonate (80 mM). The extracellular pH (pHe) values in cells of the spheroid boundary were determined using SNARF pH indicator, showing a pH of 5.3 for acidosis and pH 7 for spheroids exposed to sodium bicarbonate. The perifosine cytotoxicity was diminished in acidic conditions and increased upon alkalization suggesting the critical role of pHe and external pH on perifosine efficacy. Moreover, we defined a workflow to quantify perifosine level in 3D models and to co-localize its variable level areas with the regions of viable/apoptotic cells inside the spheroids using a combination of MALDI MSI and immunohistochemistry. Using these approaches, we verified low penetration and cytotoxicity of perifosine in the 3D setting. Alkalization of spheroid increased cleavage of caspase 8, a marker of apoptosis, despite the penetration of the drug into the spheroid remained unaltered. In conclusion, our findings suggest that alteration of the external tumor pH and pHe in 3D spheroids of CRC cell lines modulates perifosine cytotoxicity and should be considered as a possible treatment strategy.
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