EMT-mediated regulation of CXCL1/5 for resistance to anti-EGFR therapy in colorectal cancer.

The emergence of RAS/RAF mutant clone is the main feature of EGFR inhibitor resistance in KRAS wild-type colon cancer. However, its molecular mechanism is thought to be multifactorial, mainly due to cellular heterogeneity. In order to better understand the resistance mechanism in a single clone level, we successfully isolated nine cells with cetuximab-resistant (CR) clonality from in vitro system. All CR cells harbored either KRAS or BRAF mutations. Characteristically, these cells showed a higher EMT (Epithelial to mesenchymal transition) signature, showing increased EMT markers such as SNAI2. Moreover, the expression level of CXCL1/5, a secreted protein, was significantly higher in CR cells compared to the parental cells. In these CR cells, CXCL1/5 expression was coordinately regulated by SNAI2/NFKB and transactivated EGFR through CXCR/MMPI/EGF axis via autocrine singling. We also observed that combined cetuximab/MEK inhibitor not only showed growth inhibition but also reduced the secreted amounts of CXCL1/5. We further found that serum CXCL1/5 level was positively correlated with the presence of RAS/RAF mutation in colon cancer patients during cetuximab therapy, suggesting its role as a biomarker. These data indicated that the application of serum CXCL1/5 could be a potential serologic biomarker for predicting resistance to EGFR therapy in colorectal cancer.

Identification of a potentially avoidable cardiopulmonary resuscitation in hematology and oncology wards.

BACKGROUND: In-hospital cardiopulmonary resuscitation (CPR) is one of undesirable situations. We tried to identify and characterize a potentially avoidable CPR in cancer patients who were hospitalized in hematology and oncology wards. METHODS: A potentially avoidable CPR was determined based on chemotherapy setting, disease status and clinical situation at the time when a cardiopulmonary arrest occurred, by using a consensus-driven medical records review of two physicians. RESULTS: One hundred thirty-seven patients among 12,437 patients hospitalized at hematology and oncology wards between March 2003 and June 2015 (1.1%) underwent a CPR. Eighty-eight patients (64.2%) were men. The majority of patients with a CPR had lung cancer (41, 29.9%), hematologic malignancy (24, 17.5%), stomach cancer (23, 16.8%) or lymphoma (20, 14.6%). A potentially avoidable CPR was identified in 51 patients (37.2%). In a multivariate analysis, advanced diseases and certain tumor types (e.g., lung cancer, lymphoma) were significant risk factors for a potentially avoidable CPR. Of patients who received a potentially avoidable CPR, 29 patients (56.9%) did not have a do-not-resuscitate documentation. A first return of spontaneous circulation rate (ROSC) and in-hospital survival rate (IHSR) were much lower in patients with a potentially avoidable CPR than those with a CPR that was not avoidable (ROSC: 39.2% vs 53.5%, P = 0.106; IHSR: 2.0% vs 12.8%, P = 0.032, respectively). CONCLUSIONS: A potentially avoidable CPR was common at hematology and oncology wards. A potentially avoidable CPR frequently occurred in advanced diseases and certain tumor types. Furthermore, cancer patients who received a potentially avoidable CPR showed the worse prognosis.

Activation of WNT/ß-catenin signaling results in resistance to a dual PI3K/mTOR inhibitor in colorectal cancer cells harboring PIK3CA mutations.

PIK3CA is a frequently mutated gene in cancer, including about ~15 to 20% of colorectal cancers (CRC). PIK3CA mutations lead to activation of the PI3K/AKT/mTOR signaling pathway, which plays pivotal roles in tumorigenesis. Here, we investigated the mechanism of resistance of PIK3CA-mutant CRC cell lines to gedatolisib, a dual PI3K/mTOR inhibitor. Out of a panel of 29 CRC cell lines, we identified 7 harboring one or more PIK3CA mutations; of these, 5 and 2 were found to be sensitive and resistant to gedatolisib, respectively. Both of the gedatolisib-resistant cell lines expressed high levels of active glycogen synthase kinase 3-beta (GSK3ß) and harbored the same frameshift mutation (c.465_466insC; H155fs*) in TCF7, which encodes a positive transcriptional regulator of the WNT/ß-catenin signaling pathway. Inhibition of GSK3ß activity in gedatolisib-resistant cells by siRNA-mediated knockdown or treatment with a GSK3ß-specific inhibitor effectively reduced the activity of molecules downstream of mTOR and also decreased signaling through the WNT/ß-catenin pathway. Notably, GSK3ß inhibition rendered the resistant cell lines sensitive to gedatolisib cytotoxicity, both in vitro and in a mouse xenograft model. Taken together, these data demonstrate that aberrant regulation of WNT/ß-catenin signaling and active GSK3ß induced by the TCF7 frameshift mutation cause resistance to the dual PI3K/mTOR inhibitor gedatolisib. Cotreatment with GSK3ß inhibitors may be a strategy to overcome the resistance of PIK3CA- and TCF7-mutant CRC to PI3K/mTOR-targeted therapies.