Current in vitro gut models lack physiological relevance, and various approaches have been taken to improve current cell culture models. For example, mimicking the three-dimensional (3D) tissue structure or fluidic environment has been shown to improve the physiological function of gut cells. Here, we incorporated a collagen scaffold that mimics the human intestinal villi into a microfluidic device, thus providing cells with both 3D tissue structure and fluidic shear. We hypothesized that the combined effect of 3D structure and fluidic shear may provide cells with adequate stimulus to induce further differentiation and improve physiological relevance. The physiological function of our '3D gut chip' was assessed by measuring the absorptive permeability of the gut epithelium and activity of representative enzymes, as well as morphological evaluation. Our results suggest that the combination of fluidic stimulus and 3D structure induces further improvement in gut functions. Our work provides insight into the effect of different tissue environment on gut cells.

In vitro prediction of the probable rapid emergence of resistance to a drug in tumors could act to winnow out potential candidates for further costly development. We have developed a microfluidic device consisting of ∼500 hexagonal microcompartments that provides a complex ecology with wide ranges of drug and nutrient gradients and local populations. This ecology of a fragmented metapopulation induced the drug resistance in stage IV U87 glioblastoma cells to doxorubicin in 7 d. Exome and transcriptome sequencing of the resistant cells identified mutations and differentially expressed genes. Gene ontology and pathway analyses of the genes identified showed that they were functionally relevant to the established mechanisms of doxorubicin action. Specifically, we identified (i) a frame-shift insertion in the filamin-A gene, which regulates the influx and efflux of topoisomerase II poisons; (ii) the overexpression of aldo-keto reductase enzymes, which convert doxorubicin into doxorubicinol; and (iii) activation of NF-κB via alterations in the nucleotide-binding oligomerization domain (NOD)-like receptor signaling pathway from mutations in three genes (CARD6, NSD1, and NLRP13) and the overexpression of inflammatory cytokines. Functional experiments support the in silico analyses and, together, demonstrate the effects of these genetic changes. Our findings suggest that, given the rapid evolution of resistance and the focused response, this technology could act as a rapid screening modality for genetic aberrations leading to resistance to chemotherapy as well as counter selection of drugs unlikely to be successful ultimately.

Expression of the CD44 gene is upregulated in breast cancer cells and is correlated with patient survival. Aberrant CD44 expression promotes tumor progression and metastasis. In the present study, we investigated the role of zerumbone (ZER) on regulatory mechanisms of CD44 expression in breast cancer cells. Our results showed that CD44 expression was significantly increased by epidermal growth factor receptor (EGFR) ligands in SKBR3 breast cancer cells. In contrast, EGF-induced CD44 expression was decreased by a MEK1/2 inhibitor, UO126, or STAT3 inhibitor, STAT3 VI, respectively. Notably, ZER downregulated the basal level of CD44 expression in CD44+ breast cancer cells. In addition, the induction of CD44 expression by EGFR ligands, EGF or TGF-α, was markedly decreased by ZER treatment. Finally, we investigated the inhibitory mechanism of ZER on EGF-induced CD44 expression. Our results showed that EGF-induced phosphorylation of STAT3 was completely suppressed by ZER. Collectively, ZER suppressed EGF-induced CD44 expression through inhibition of the STAT3 pathway. Therefore, we suggested that ZER may act as a promising therapeutic drug for the treatment of breast cancer.

Stanniocalcin‑1 (STC‑1), a secreted glycoprotein, is highly expressed in a variety of human malignancies. However, the role of STC‑1 has not been fully elucidated in breast cancer cells. Here, we investigated whether STC‑1 acts as a prognostic factor in triple‑negative breast cancer (TNBC) patients, and we explored the cellular mechanism in breast cancer cells. The level of STC‑1 expression was directly associated with the relapse‑free and overall survival of basal‑type breast cancer patients. Breast cancer patients with a high level of STC‑1 had poor prognosis. In addition, our results showed that the level of STC‑1 expression was markedly higher in TNBC than in non‑TNBC cells. Invasiveness of the TNBC cells was also significantly increased in response to recombinant human STC‑1 treatment. In contrast, the invaded cell numbers were completely decreased by STC‑1 siRNA overexpression in the Hs578T and MDA‑MB‑231 TNBC cells. Our results showed that the phosphorylation of c‑Jun N‑terminal protein kinase (JNK) and c‑Jun was increased after STC‑1 treatment but not the phosphorylation of ERK and p38 MAPKs in the Hs578T and MDA‑MB‑231 TNBC cells. Furthermore, expression of one invasion‑related gene MMP‑9, was increased by STC‑1 treatment. STC‑1‑induced MMP‑9 expression was suppressed by SP600125 (a JNK inhibitor) in the Hs578T cells. STC‑1‑induced cell invasiveness was also inhibited by SP600125. Taken together, we demonstrated that aberrant STC‑1 expression is associated with poor prognosis and stimulates the invasiveness of TNBC cells through the JNK/c‑Jun‑dependent signaling pathway.