Unlike plants which have special gravity-sensing cells, such special cells in animals are yet to be discovered. However, microgravity, the condition of apparent weightlessness, causes bone, muscular and immune system dysfunctions in astronauts following spaceflights. Decades of investigations show correlations between these organ and system-level dysfunctions with changes induced at the cellular level both by simulated microgravity as well as microgravity conditions in outer space. Changes in single bone, muscle and immune cells include morphological abnormalities, altered gene expression, protein expression, metabolic pathways and signaling pathways. These suggest that human cells mount some response to microgravity. However, the implications of such adjustments on many cellular functions and responses are not clear. Here, we addressed the question whether microgravity induces alterations to drug response in cancer cells. We used both adherent cancer cells (T98G) and cancer cells in suspension (K562) to confirm known effects of microgravity and then treated the K562 cells with common cancer drugs (hydroxyurea and paclitaxel) following 48 hours of exposure to microgravity via a NASA-developed rotary cell culture system. Fluorescence-guided morphometry revealed microgravity-induced loss of the significant reduction (p < 0.0l) to the nuclear to cytoplasm ratio of cancer cells treated with hydroxyurea. Our results call for more studies on impact of microgravity on cellular drug-response, in view of the growing need for space medicine, as space exploration grows.

There is rapidly emerging evidence from pre-clinical studies, patient samples and patient subpopulations that certain chemotherapeutics inadvertently produce prometastatic effects. Prior to this, we showed that doxorubicin and daunorubicin, stiffen cells before causing cell death, predisposing the cells to clogging and extravasation, the latter being a step in metastasis. Here, we investigate which other anti-cancer drugs might have similar prometastatic effects by altering the biophysical properties of cells. We treat myelogenous (K562) leukemic cancer cells with the drugs nocodazole and hydroxyurea, and then measure their mechanical properties using the microfluidic microcirculation mimetic (MMM) device, which mimics aspects of blood circulation and enables the measurement of cell mechanical properties via transit times through the device. We also quantify the morphological properties of cells to explore biophysical mechanisms underlying the MMM results. Results from MMM measurements show that nocodazole- and hydroxyurea-treated K562 cells exhibit significantly altered transit times. Nocodazole caused significant (p < 0.01) increase in transit times, implying a stiffening of cells. This work shows the feasibility of using the MMM to explore possible biophysical mechanisms that might contribute to chemotherapy-induced metastasis. Our work also suggests cell mechanics as a therapeutic target for much needed antimetastatic strategies in general.

Nanoparticle-mediated radiation therapy (NPRT) is an emerging modality for radiosensitization of highly resistant cancers such as brain cancers. This is due to the ability of specific nanoparticles (NPs) to increase physical dose deposition and subsequent direct damage to cells and DNA within their local vicinity, through enhanced generation of reactive oxygen species, ROS. Here, we report the successful use of PEGylated (biocompatible) core-shell quantum dots (QDs) and carbon quantum dots (CQDs) to simultaneously enhance and assess ROS generation while radiosensitizing highly radioresistant brain cancer cell lines: T98G and U87 Glioblastoma cells. Relative peak fluorescence intensity ratio calculations and average intensity comparisons show highly significant (***p<0.001) enhancement of ROS generation, for 5 Gy and 20 Gy irradiation, applied using a Faxitron Cell Irradiator. By quantifying post-radiotherapy cell attachment, proliferation, migration, cell survival and cell death using electric cell-substrate impedance sensing and clonogenic assays, we demonstrate potentially improved in vitro radiotherapeutic outcomes for brain cancer cells radiosensitized using PEGylated CdSe/ZnS QDs and CQDs.