Asymmetrical cell division (ACD) maintains the proper number of stem cells to ensure self-renewal. In cancer cells, the deregulation of ACD disrupts the homeostasis of the stem cell pool and promotes tumour growth. However, this mechanism is unclear. Here, we show a reduction of ACD in spheroid-derived colorectal cancer stem cells (CRCSCs) compared with differentiated cancer cells. The epithelial-mesenchymal transition (EMT) inducer Snail is responsible for the ACD-to-symmetrical cell division (SCD) switch in CRCSCs. Mechanistically, Snail induces the expression of microRNA-146a (miR-146a) through the β-catenin-TCF4 complex. miR-146a targets Numb to stabilize β-catenin, which forms a feedback circuit to maintain Wnt activity and directs SCD. Interference with the Snail-miR-146a–β-catenin loop by inhibiting the MEK or Wnt activity reduces the symmetrical division of CRCSCs and attenuates tumorigenicity. In colorectal cancer patients, the Snail(High)Numb(Low) profile is correlated with cetuximab resistance and a poorer prognosis. This study elucidates a unique mechanism of EMT-induced CRCSC expansion.
LEARNING OBJECTIVESAfter completing this course, the reader will be able to:1. Identify the clinical features of oxaliplatin-induced neuropathy.2. Discuss the current approaches for managing chemotherapy-induced neuropathy.3. Explain the rationale for using glutamine in preventing oxaliplatin-induced neuropathy.Access and take the CME test online and receive 1 AMA PRA Category 1 Credit ™ at CME.TheOncologist.com CME CME
ABSTRACTOxaliplatin is effective in the treatment of metastatic colorectal cancer (MCRC) patients; however, severe neurotoxicity develops frequently. To assess the efficacy of oral glutamine for preventing neuropathy induced by oxaliplatin, a pilot study was performed. A total of 86 patients with MCRC treated at Taipei Veterans General Hospital were enrolled. Oxaliplatin (85 mg/m 2 , days 1 and 15) plus weekly bolus 5-fluorouracil (5-FU; 500 mg/m 2 ) and folinic acid (FA; 20 mg/m 2 ) on days 1, 8, and 15 were given every 28 days as firstline treatment. Patients were randomized to receive (glutamine group; n ؍ 42) or not receive (control group; n ؍ 44) glutamine (15 g twice a day for seven consecutive days every 2 weeks starting on the day of oxaliplatin infusion). Efficacy of chemotherapy, neurological toxicity, and electrophysiological alterations were assessed. A lower percentage of grade 1-2 peripheral neuropathy was observed in the glutamine group (16.7% versus 38.6%) after two cycles of treatment, and a significantly lower incidence of grade 3-4 neuropathy was noted in the glutamine group after four cycles (4.8% versus 18.2%) and six cycles (11.9% versus 31.8%). By adding glutamine, interference with activities of daily living was lower (16.7% versus 40.9%), and need for oxaliplatin dose reduction was lower (7.1% versus 27.3%). There were no significant between-group differences in response to chemotherapy (52.4% versus 47.8%), electrophysiological abnormalities, grade 3-4 non-neurological toxicities (26.2% versus 22.8%), or survival. These data indi- Disclosure of potential conflicts of interest is found at the end of this article.
The dynamic cell–cell communication is essential for tissue homeostasis in normal physiological circumstances and contributes to a diversified tumor microenvironment. Although exosomes are extracellular vesicles that actively participate in cell–cell interaction by shutting cellular components, impacts of tumor exosomes in the context of cancer stemness remain elusive. Here, we expand colorectal cancer stem cells (CRCSCs) as cancer spheroids and demonstrate that the β‐catenin/Tcf‐4‐activated RAB27B expression is required for the secretion of CRCSC exosomes. In an exosomal RNA sequencing analysis, a switch of exosomal RNA species from retrotransposons to microRNAs (miRNAs) is identified upon expanding CRCSCs. miRNA‐146a‐5p (miR‐146a) is the major miRNA in CRCSC exosomes and exosomal miR‐146a promotes stem‐like properties and tumorigenicity by targeting Numb in recipient CRC cells. Among 53 CRC patients, those with abundant exosomal miR‐146a expression in serum exhibits higher miR‐146aHigh/NumbLow CRCSC traits, an increased number of tumor‐filtrating CD66(+) neutrophils and a decreased number of tumor‐infiltrating CD8(+) T cells. Our study elucidates a unique mechanism of tumor exosome‐mediated stemness expansion.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.