Ca:Mg ratio, medium-chain fatty acids, and the gut microbiome.

BACKGROUND & AIMS: Ketogenic medium-chain fatty acids (MCFAs) with profound health benefits are commonly found in dairy products, palm kernel oil and coconut oil. We hypothesize that magnesium (Mg) supplementation leads to enhanced gut microbial production of MCFAs and, in turn, increased circulating MCFAs levels. METHODS: We tested this hypothesis in the Personalized Prevention of Colorectal Cancer Trial (PPCCT) (NCT01105169), a double-blind 2 × 2 factorial randomized controlled trial enrolling 240 participants. Six 24-h dietary recalls were performed for all participants at the baseline and during the intervention period. Based on the baseline 24-h dietary recalls, the Mg treatment used a personalized dose of Mg supplementation that would reduce the calcium (Ca): Mg intake ratio to around 2.3. We measured plasma MCFAs, sugars, ketone bodies and tricarboxylic acid cycle (TCA cycle) metabolites using the Metabolon's global Precision Metabolomics™ LC-MS platform. Whole-genome shotgun metagenomics (WGS) sequencing was performed to assess microbiota in stool samples, rectal swabs, and rectal biopsies. RESULTS: Personalized Mg treatment (mean dose 205.58 mg/day with a range from 77.25 to 389.55 mg/day) significantly increased the plasma levels of C7:0, C8:0, and combined C7:0 and C8:0 by 18.45%, 25.28%, and 24.20%, respectively, compared to 14.15%, 10.12%, and 12.62% decreases in the placebo arm. The effects remain significant after adjusting for age, sex, race and baseline level (P = 0.0126, P = 0.0162, and P = 0.0031, respectively) and FDR correction at 0.05 (q = 0.0324 for both C7:0 and C8:0). Mg treatment significantly reduced the plasma level of sucrose compared to the placebo arm (P = 0.0036 for multivariable-adjusted and P = 0.0216 for additional FDR correction model) whereas alterations in daily intakes of sucrose, fructose, glucose, maltose and C8:0 from baseline to the end of trial did not differ between two arms. Mediation analysis showed that combined C7:0 and C8:0 partially mediated the effects of Mg treatment on total and individual ketone bodies (P for indirect effect = 0.0045, 0.0043, and 0.03, respectively). The changes in plasma levels of C7:0 and C8:0 were significantly and positively correlated with the alterations in stool microbiome α diversity (r = 0.51, p = 0.0023 and r = 0.34, p = 0.0497, respectively) as well as in stool abundance for the signatures of MCFAs-related microbiota with acyl-ACP thioesterase gene producing C7:0 (r = 0.46, p = 0.0067) and C8:0 (r = 0.49, p = 0.003), respectively, following Mg treatment. CONCLUSIONS: Optimizing Ca:Mg intake ratios to around 2.3 through 12-week personalized Mg supplementation leads to increased circulating levels of MCFAs (i.e. C7:0 and C8:0), which is attributed to enhanced production from gut microbial fermentation and, maybe, sucrose consumption.

Tipifarnib enhances anti-EGFR activity of cetuximab in non-HRas mutated head and neck squamous cell carcinoma cancer (HNSCC).

OBJECTIVE: To test the potential ability of tipifarnib to impair proliferation and to enhance the activity of the EGFR inhibitor cetuximab in wild-type H-Ras HNSCC, which accounts for the majority of HNSCC. MATERIALS AND METHODS: Cell growth, apoptosis and signaling changes in HNSCC cells following tipifarnib exposure in vitro were assessed by SRB, colony formation assay, annexin V staining and Western blot, respectively. A patient-derived xenograft (PDX) animal model was adopted to evaluate the efficacy of tipifarnib in vivo with and without cetuximab. RESULTS: Treatment of wild-type H-Ras HNSCC cell lines in vitro with tipifarnib reduced cell growth and increased levels of defarnesylated H-Ras in a dose-dependent manner. In a PDX mouse model, treatment with single-agent tipifarnib led to only near-significant growth inhibition. The addition of cetuximab resulted in increased anti-proliferative effect both in culture and in PDX models, which was also mirrored by Western blot and apoptosis assay results. CONCLUSION: Tipifarnib has only a moderate ability to slow tumor growth as a single agent in HNSCC with wild type H-Ras, despite specifically inhibiting the farnesyltransferase upon which the function of H-Ras depends. The combination of cetuximab and tipifarnib appears to enhance the anti-proliferative effect of single-agent tipifarnib and marginally enhance that of single agent cetuximab. These findings deserve further evaluation.

A Historic Perspective and Overview of H-Ras Structure, Oncogenicity, and Targeting.

H-Ras is a unique isoform of the Ras GTPase family, one of the most prominently mutated oncogene families across the cancer landscape. Relative to other isoforms, though, mutations of H-Ras account for the smallest proportion of mutant Ras cancers. Yet, in recent years, there have been renewed efforts to study this isoform, especially as certain H-Ras-driven cancers, like those of the head and neck, have become more prominent. Important advances have therefore been made not only in the understanding of H-Ras structural biology but also in approaches designed to inhibit and impair its signaling activity. In this review, we outline historic and present initiatives to elucidate the mechanisms of H-Ras-dependent tumorigenesis as well as highlight ongoing developments in the quest to target this critical oncogene.

Diverse Long RNAs Are Differentially Sorted into Extracellular Vesicles Secreted by Colorectal Cancer Cells.

The regulation and functional roles of secreted coding and long noncoding RNAs (lncRNAs; >200 nt) are largely unknown. We previously showed that mutant KRAS colorectal cancer (CRC) cells release extracellular vesicles (EVs) containing distinct proteomes, microRNAs (miRNAs), and circular RNAs. Here, we comprehensively identify diverse classes of CRC extracellular long RNAs secreted in EVs and demonstrate differential export of specific RNAs. Distinct noncoding RNAs, including antisense transcripts and transcripts derived from pseudogenes, are enriched in EVs compared to cellular profiles. We detected strong enrichment of Rab13 in mutant KRAS EVs and demonstrate functional delivery of Rab13 mRNA to recipient cells. To assay functional transfer of lncRNAs, we implemented a CRISPR/Cas9-based RNA-tracking system to monitor delivery to recipient cells. We show that gRNAs containing export signals from secreted RNAs can be transferred from donor to recipient cells. Our data support the existence of cellular mechanisms to selectively export diverse classes of RNA.

Polymorphism of vascular endothelial growth factor -2578C/A with cancer risk: evidence from 11263 subjects.

Published data on the association between vascular endothelial growth factor (VEGF) -2578C/A polymorphism and cancer risk is inconclusive. To derive a more precise estimation of association between VEGF -2578C/A polymorphism and the risk of cancer, we performed a meta-analysis of 5415 cancer cases and 5848 controls from 16 published case-control studies. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of the association. Our meta-analysis indicated that VEGF -2578C/A polymorphism was associated with the risk of colorectal cancer under homozygote comparison (OR=0.70, 95% CI=0.53-0.92), dominant model (OR=0.72, 95% CI=0.57-0.92), and recessive model (OR=0.82, 95% CI=0.67-1.01), although no evidence of association between VEGF -2578C/A polymorphism and cancer risk was observed as we compared in the pooled analyses (homozygote comparison: OR=0.97, 95% CI=0.81-1.16). More studies are needed to detect VEGF -2578C/A polymorphism and its association with cancer in different ethnic populations incorporated with environmental exposures in the susceptibility of different kinds of cancer.

Excision repair cross complementation group 1 polymorphisms and lung cancer risk: a meta-analysis.

BACKGROUND: Several studies have evaluated the association between polymorphisms of encoding excision repair cross complementation group 1 (ERCC1) enzyme and lung cancer risk in diverse populations but with conflicting results. By pooling the relatively small samples in each study, it is possible to perform a meta-analysis of the evidence by rigorous methods. METHODS: Embase, Ovid, Medline and Chinese National Knowledge Infrastructure were searched. Additional studies were identified from references in original studies or review articles. Articles meeting the inclusion criteria were reviewed systematically, and the reported data were aggregated using the statistical techniques of meta-analysis. RESULTS: We found 3810 cases with lung cancer and 4332 controls from seven eligible studies. T19007C polymorphism showed no significant effect on lung cancer risk (C allele vs. T allele: odds ratio (OR) = 0.91, 95% confidence interval (CI) = 0.80 - 1.04; CC vs. TT: OR = 0.76, 95%CI = 0.56 - 1.02; CC vs. (CT + TT): OR = 0.96, 95%CI = 0.84 - 1.10). Similarly, there was no significant main effects for T19007C polymorphism on lung cancer risk when stratified analyses by ethnicity (Chinese or Caucasian). No significant association was found between C8092A polymorphism (3060 patients and 2729 controls) and the risk of lung cancer (A allele vs. C allele: OR = 1.03, 95%CI = 0.95 - 1.11; AA vs. CC: OR = 1.08, 95%CI = 0.88 - 1.33; AA vs. (AC + CC): OR = 1.08, 95%CI = 0.88 - 1.31). CONCLUSION: We found little evidence of an association between the T1900C or C8092A polymorphisms of ERCC 1 and the risk of lung cancer in Caucasian or Han Chinese people.

Vascular endothelial growth factor +936C/T and +405G/C polymorphisms and cancer risk: a meta-analysis.

BACKGROUND AND AIMS: A number of investigators have studied the possible association between vascular endothelial growth factor (VEGF) polymorphisms and cancer risk, but the results have been conflicting. To examine the risk of cancer associated with the +936C/T and +405G/C polymorphisms of VEGF, all available studies were considered in the present meta-analysis. METHODS: We performed a computerized search of PubMed and Embase database for relevant studies. Articles meeting the inclusion criteria were reviewed systematically, and the reported data were aggregated using the statistical techniques of meta-analysis. RESULTS: Overall, the 936C allele showed no significant effect on cancer risk compared with the 936T allele in all subjects (OR = 0.77, 95% CI = 0.53-1.14; random model). Similarly, no significant effect of 405G allele compared with 405C on cancer risk was found (OR = 1.08, 95% CI = 0.94-1.24; random model). It indicated that the VEGF +936C/T and +405G/C polymorphisms might not be risk factors for cancer, but the 936C allele was associated with a decreased risk of oral cancer (OR = 0.72, 95% CI = 0.53-0.97; fixed model). CONCLUSIONS: The evidence from our meta-analysis supports that there was an association between 936C allele and decreased oral cancer risk, although no evidence of association between VEGF +936C/T or +405G/C polymorphism and cancer was observed in all examined patients. Further studies based on larger, stratified population are required to explore the role of VEGF polymorphisms on cancer risk.