Partial or even complete cancer regression can be achieved in some patients with current cancer treatments. However, such initial responses are almost always followed by relapse, with the recurrent cancer being resistant to further treatments. The discovery of therapeutic approaches that counteract relapse is, therefore, essential for advancing cancer medicine. Cancer cells are extremely heterogeneous, even in each individual patient, in terms of their malignant potential, drug sensitivity, and their potential to metastasize and cause relapse. Indeed, hypermalignant cancer cells, termed cancer stem cells or stemness-high cancer cells, that are highly tumorigenic and metastatic have been isolated from cancer patients with a variety of tumor types. Moreover, such stemness-high cancer cells are resistant to conventional chemotherapy and radiation. Here we show that BBI608, a small molecule identified by its ability to inhibit gene transcription driven by Stat3 and cancer stemness properties, can inhibit stemness gene expression and block spherogenesis of or kill stemnesshigh cancer cells isolated from a variety of cancer types. Moreover, cancer relapse and metastasis were effectively blocked by BBI608 in mice. These data demonstrate targeting cancer stemness as a novel approach to develop the next generation of cancer therapeutics to suppress cancer relapse and metastasis.cancer stemness | relapse | BBI608 C urrent cancer treatments ultimately fail owing to metastasis and relapse. Although chemotherapy can induce partial or even complete cancer regression in some patients, such initial responses are invariably followed by relapse, with the recurrent cancer being highly resistant to further chemotherapy, resulting in very limited survival benefits (1-3). Modern therapeutics designed to specifically target activating mutations are quite effective in inducing cancer regression in patients driven by such activating mutations; however, these treatments are also invariably followed by relapse with tumors that no longer respond to the targeted agent (2, 3). The discovery of novel therapeutic approaches that counteract cancer relapse is, therefore, urgently required for advancing cancer treatment.The idea that cancer is composed of a group of near-homogenous, ectopically growing cells has been replaced with a more complex model in which cancer cells are extremely heterogeneous, even in each individual patient, in terms of their malignant potential to metastasize and cause relapse. The increased understanding of the genomic and proteomic complexity of tumor heterogeneity further highlights the extreme heterogeneity of cancer cells (4).Subpopulations of cancer cells with extremely high tumorigenic potential, termed cancer stem cells or stem-like cancer cells, have been isolated from cancer patients with a variety of tumor types (5-13) and found to have high stemness properties (5-15). Stemness, initially defined by the expression of stem cells genes, is a property shared by embryonic stem cells and adult stem cells (16). In ...

The ulcer-causing gastric pathogen Helicobacter pylori is the only bacterium known to colonize the harsh acidic environment of the human stomach. H. pylori survives in acidic conditions by producing urease, which catalyzes hydrolysis of urea to yield ammonia thus elevating the pH of its environment. However, the manner in which H. pylori is able to swim through the viscoelastic mucus gel that coats the stomach wall remains poorly understood. Previous rheology studies on gastric mucin, the key viscoelastic component of gastric mucus, indicate that the rheology of this material is pH dependent, transitioning from a viscous solution at neutral pH to a gel in acidic conditions. Bulk rheology measurements on porcine gastric mucin (PGM) show that pH elevation by H. pylori induces a dramatic decrease in viscoelastic moduli. Microscopy studies of the motility of H. pylori in gastric mucin at acidic and neutral pH in the absence of urea show that the bacteria swim freely at high pH, and are strongly constrained at low pH. By using two-photon fluorescence microscopy to image the bacterial motility in an initially low pH mucin gel with urea present we show that the gain of translational motility by bacteria is directly correlated with a rise in pH indicated by 2 ,7 -Bis-(2-Carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF), a pH sensitive fluorescent dye. This study indicates that the helicoidal-shaped H. pylori does not bore its way through the mucus gel like a screw through a cork as has previously been suggested, but instead achieves motility by altering the rheological properties of its environment.H. pylori ͉ bacterial motility ͉ rheology ͉ pH ͉ gelation

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