BACKGROUND Circulating tumor cells (CTCs) can be used clinically to treat cancer. As a diagnostic tool, the CTC count can be used to follow disease progression, and as a treatment tool, CTCs can be used to rapidly develop personalized therapeutic strategies. To be effectively used, however, CTCs must be isolated at high purity without inflicting cellular damage. METHODS We designed a microscale flow device with a functionalized surface of E-selectin and antibody molecules against epithelial markers. The device was additionally enhanced with a halloysite nanotube coating. We created model samples in which a known number of labeled cancer cells were suspended in healthy whole blood to determine device capture efficiency. We then isolated and cultured primary CTCs from buffy coat samples of patients diagnosed with metastatic cancer. RESULTS Approximately 50% of CTCs were captured from model samples. Samples from 12 metastatic cancer patients and 8 healthy participants were processed in nanotube-coated or smooth devices to isolate CTCs. We isolated 20–704 viable CTCs per 3.75-mL sample, achieving purities of 18%–80% CTCs. The nanotube-coated surface significantly improved capture purities (P = 0.0004). Experiments suggested that this increase in purity was due to suppression of leukocyte spreading. CONCLUSIONS The device successfully isolates viable CTCs from both blood and buffy coat samples. The approximately 50% capture rate with purities >50% with the nanotube coating demonstrates the functionality of this device in a clinical setting and opens the door for personalized cancer therapies.

We have previously synthesized a phospholipid-gemcitabine conjugate and a phospholipid-cytosine arabinoside conjugate that we tested in different human cancer cell lines. The gemcitabine conjugate was more cytotoxic to the cancer cells tested than the cytosine arabinoside (ara-C) conjugate. The focus here was to elucidate the mechanism of action of the conjugate molecule and its ability to bypass certain drug-resistance mechanisms. In contrast to gemcitabine, the gemcitabine conjugate did not enter the cell via the human equilibrative nucleoside transporter (hENT1). Additionally, the gemcitabine conjugate was not a substrate for the multidrug resistance efflux pump, MDR-1, even though the molecule is more lipophilic. Finally, we showed that deoxycytidine kinase (dCK) was not required for the activation of the gemcitabine conjugate. As expected, cells overexpressing dCK were more sensitive to gemcitabine whereas cells overexpressing dCK were not more sensitive to the gemcitabine conjugate. Taken together, these results suggest that the gemcitabine conjugate may be therapeutically superior to gemcitabine due to the conjugate's ability to bypass three resistance mechanisms that often render gemcitabine ineffective as an anticancer agent.

Iron chelators have traditionally been used in the treatment of iron overload. Recently, chelators have also been explored for their ability to limit oxidant damage in cardiovascular, neurologic, and inflammatory disease as well as to serve as anti-cancer agents. To determine the mechanism of cell death induced by iron chelators, we assessed the time course and pathways of caspase activation during apoptosis induced by iron chelators. We report that the chelator tachpyridine sequentially activates caspases 9, 3, and 8. These caspases were also activated by the structurally unrelated chelators dipyridyl and desferrioxamine. The critical role of caspase activation in cell death was supported by microinjection experiments demonstrating that p35, a broad spectrum caspase inhibitor, protected HeLa cells from chelator-induced cell death. Apoptosis mediated by tachpyridine was not prevented by blocking the CD95 death receptor pathway with a Fas-associated death domain protein (FADD) dominant-negative mutant. In contrast, chelator-mediated cell death was blocked in cells microinjected with Bcl-XL and completely inhibited in cells microinjected with a dominant-negative caspase 9 expression vector. Caspase activation was not observed in cells treated with N-methyl tachpyridine, an N-alkylated derivative of tachpyridine which lacks an ability to react with iron. These results suggest that activation of a mitochondrial caspase pathway is an important mechanism by which iron chelators induce cell death.

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Circulating tumor cells (CTCs) are believed to be responsible for the development of metastatic disease. Over the last several years there has been a great interest in understanding the biology of CTCs to understand metastasis, as well as for the development of companion diagnostics to predict patient response to anti-cancer targeted therapies. Understanding CTC biology requires innovative technologies for the isolation of these rare cells. Here we review several methods for the detection, capture, and analysis of CTCs and also provide insight on improvements for CTC capture amenable to cellular therapy applications.

Members of the phosphatidylinositol 3-kinase-related kinase family, in particular the ataxia-telangiectasia mutated (ATM) kinase and the catalytic subunit of the DNA

Personalized medicine holds great promise for cancer treatment, with the potential to address challenges associated with drug sensitivity and interpatient variability. Circulating tumor cells (CTC) can be useful for screening cancer drugs as they may reflect the severity and heterogeneity of primary tumors. Here we present a platform for rapidly evaluating individualized drug susceptibility. Treatment efficacy is evaluated directly in blood, employing a relevant environment for drug administration, and assessed by comparison of CTC counts in treated and control samples. Multiple drugs at varying concentrations are evaluated simultaneously to predict an appropriate therapy for individual patients.