No abstract

Anoikis is a critical obstacle to cancer metastasis. Colorectal cancer (CRC) exhibits a high rate of metastasis, leading to death, and the mechanisms involved in anoikis resistance are still unclear. We identified that the fatty acid oxidation (FAO) pathway was activated in detached CRC cells. Multiple genes in the FAO pathway, specifically the rate-limiting enzyme CPT1A, were upregulated in CRC cells grown in suspension. Reactive oxygen species elimination mediated by CPT1A in CRC cells was vital to anoikis resistance. In vivo experiments showed that CPT1A-suppressed CRC cells colonized the lung at a much lower rate than normal CRC cells, suggesting that CPT1A-mediated FAO activation increased metastatic capacity. In clinical tissue specimens from CRC patients, elevated expression of CPT1A was observed in metastatic sites compared with primary sites. Our results demonstrate that CPT1A-mediated FAO activation induces CRC cells to resist anoikis, suggesting that CPT1A is an attractive target for treating metastatic CRC.

Background Overcoming oxidative stress is a critical step for tumor progression; however, the underlying mechanisms in colorectal cancer (CRC) remain unclear. Methods We investigated nicotinamide adenine dinucleotide (phosphate) (NAD(P))-dependent enzyme methylene tetrahydrofolate dehydrogenase 2 (MTHFD2) expression, clinical relevance, redox modification, and molecular mechanisms using the CRC cells and tissues (n = 462 paired samples). The antitumor effects of MTHFD2 inhibitor LY345899 on CRC tumorigenesis and metastasis were evaluated in vitro and in vivo. Data analysis used Kaplan-Meier, Pearson’s correlation, and Student t test where appropriate. All statistical tests were two-sided. Results Here, we report that the patients with high expression of MTHFD2 have a shorter overall survival (HR = 1.62, 95% CI = 1.12 to 2.36, P = .01) and disease-free survival (HR = 1.55, 95% CI = 1.07 to 2.27, P = .02) than patients with low MTHFD2 expression. Suppression of MTHFD2 disturbs NADPH and redox homeostasis and accelerates cell death under oxidative stress, such as hypoxia or anchorage independence ( P ≤ .01 for all). Also, genetic or pharmacological inhibition of MTHFD2 suppresses CRC cell growth and lung and peritoneal metastasis in cell-based xenografts (n = 5–8 mice per group). Importantly, LY345899 treatment statistically significantly suppresses tumor growth and decreases the tumor weight in CRC patient-derived xenograft models (n = 10 mice per group, mean [SD] tumor weight of the vehicle-treated group was 1.83 [0.19] mg vs 0.74 [0.30] mg for the LY345899-treated group, P < .001) Conclusions Our study presents evidence that MTHFD2 confers redox homeostasis and promotes CRC cell growth and metastasis. The folate analog LY345899 as MTHFD2 inhibitor displays therapeutic activity against CRC and warrants further clinical investigation for CRC treatment.

In this study, we evaluated the 8th edition of the Union for International Cancer Control (UICC)/AJCC staging system for nasopharyngeal carcinoma (NPC) in an endemic area, with the aim of validating its applicability and providing further information for future refinements. A total of 1,790 patients with newly diagnosed, non-distant metastatic, histologically proven NPC treated with intensity-modulated radiotherapy (IMRT) were retrospectively reviewed. The performance of various staging systems was compared using the Akaike information criterion (AIC) and Harrell's concordance index (c-index). For N (node) category, the survival curves of different groups according to the 8th edition were well-separated, and the prognostic model predicted outcomes fairly well. The 8th edition had higher AIC and c-index values for all end points than the 7th edition. However, probably due to the improved locoregional control provided by IMRT, the survival curves for T2 and T3 almost overlapped, without significant differences in locoregional failure-free survival (=.606) and disease-free survival (=.735). Due to the difficultly of differentiating T2 and T3, the AIC and c-index values were similar for the T categories of the 7th and 8th editions. Similarly, the overall survival and disease-free survival curves for stage II and III disease were not clearly separated for either the 8th or 7th editions. The 8th edition of the UICC/AJCC staging system for NPC enables more accurate prediction of treatment outcomes. However, several limitations need to be addressed in future editions, and it would be reasonable to further optimize the T category classification.

Background: Tumor mutational burden (TMB) has been widely studied as a predictive biomarker of response to immune checkpoint inhibitors (ICIs). Besides, evidence suggests frameshift indels are a highly immunogenic mutational class and thus a potentially superior biomarker. However, the general prognostic impact of TMB and indel burden in patients with solid tumors has not been systematically investigated. Methods:We analyzed 20 primary solid cancer types from The Cancer Genome Atlas (TCGA) database.Clinicopathologic factors, TMB and indel burden were collected or calculated. For each cancer type, the impact of TMB or indel burden on overall survival (OS) was evaluated using the Kaplan-Meier method and Cox regression with the method of inverse probability of treatment weighting.Results: Twenty cancer types from 6,035 patients were analyzed. Survival analysis showed that TMB had a significant impact on OS in 14 out of these 20 cancer types. According to the general survival impact of TMB, they could be classified into three groups, namely the TMB-Worse (eight cancer types), TMB-Better (six cancer types) and TMB-Similar (six cancer types) group, in which higher TMB was associated with inferior, superior, or similar OS, respectively. The survival impacts of TMB in the TMB-Worse and TMB-Better groups were generally consistent when limited to genes from two FDA-approved panels. Notably, in two out of the six cancer types in the TMB-Similar group, the indel burden significantly affected OS.Conclusions: TMB, as well as indel burden, has divergent prognostic impact in different cancer types, thus could be incorporated in prognostication and risk stratification. More importantly, the general prognostic impact should be taken into account when establishing the predictive function of TMB to ICI treatment.