Genome-Wide Gene-Environment Interaction Analyses to Understand the Relationship between Red Meat and Processed Meat Intake and Colorectal Cancer Risk

BACKGROUND

High red meat and/or processed meat consumption are established colorectal cancer risk factors. We conducted a genome-wide gene-environment (GxE) interaction analysis to identify genetic variants that may modify these associations.

METHODS

A pooled sample of 29,842 colorectal cancer cases and 39,635 controls of European ancestry from 27 studies were included. Quantiles for red meat and processed meat intake were constructed from harmonized questionnaire data. Genotyping arrays were imputed to the Haplotype Reference Consortium. Two-step EDGE and joint tests of GxE interaction were utilized in our genome-wide scan.

RESULTS

Meta-analyses confirmed positive associations between increased consumption of red meat and processed meat with colorectal cancer risk [per quartile red meat OR = 1.30; 95% confidence interval (CI) = 1.21-1.41; processed meat OR = 1.40; 95% CI = 1.20-1.63]. Two significant genome-wide GxE interactions for red meat consumption were found. Joint GxE tests revealed the rs4871179 SNP in chromosome 8 (downstream of HAS2); greater than median of consumption ORs = 1.38 (95% CI = 1.29-1.46), 1.20 (95% CI = 1.12-1.27), and 1.07 (95% CI = 0.95-1.19) for CC, CG, and GG, respectively. The two-step EDGE method identified the rs35352860 SNP in chromosome 18 (SMAD7 intron); greater than median of consumption ORs = 1.18 (95% CI = 1.11-1.24), 1.35 (95% CI = 1.26-1.44), and 1.46 (95% CI = 1.26-1.69) for CC, CT, and TT, respectively.

CONCLUSIONS

We propose two novel biomarkers that support the role of meat consumption with an increased risk of colorectal cancer.

IMPACT

The reported GxE interactions may explain the increased risk of colorectal cancer in certain population subgroups.

Disparities among Black and Hispanic colorectal cancer patients: Findings from the California Cancer Registry

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer in California and second among Hispanic/Latinx (H/L) males. Data from the California Cancer Registry were utilized to investigate the differential impact on CRC outcomes from demographic and clinical characteristics among non-Hispanic white (NHW), non-Hispanic Black (NHB), U.S. born (USB), and non-U.S. born (NUSB) H/L patients diagnosed during 1995-2020.

METHODS

We identified 248,238 NHW, 28,433 NHB, and 62,747 H/L cases (32,402 NUSB and 30,345 USB). Disparities across groups were evaluated through case frequencies, odds ratios (OR) from logistic regression, and hazard ratios (HR) from Cox regression models. All statistical tests were two-sided.

RESULTS

NHB patients showed a higher proportion of colon tumors (75.8%) than NHW (71.5%), whereas both NUSB (65.9%) and USB (66.9%) H/L cases had less (p < 0.001). In multivariate models, NUSB H/L cases were 15% more likely than NHW to have rectal cancer. Compared to NHW, NHB cases had the greatest proportion of Stage IV diagnoses (26.0%) and were more likely to die of CRC (multivariate HR = 1.12; 95% CI = 1.10-1.15). Instead, NUSB H/L patients were less likely to die of CRC (multivariate HR = 0.87; 95% CI = 0.85-0.89) whereas USB H/L did not differ from NHW.

CONCLUSIONS

NHB and H/L cases have more adverse characteristics at diagnosis compared to NHW cases, with NHB cases being more likely to die from CRC. However, NUSB H/Ls cases showed better survival than NHW and US born H/L patients. These findings highlight the importance of considering nativity among H/L populations to understand cancer disparities.

Treatment of Parkinson's disease with aporphines. Possible role of growth hormone

To avoid the main drawbacks of prolonged treatment with levodopa (involuntary movements and the "on-off" phenomenon), we administered apomorphine by mouth to 14 patients with Parkinson's disease. This treatment caused azotemia, which we circumvented by switching to N-propylnoraporpine, whose nephrotoxic dose (80 mg six times per day) was larger than its therapeutic dose (10 to 15 mg six times per day). Slowly increasing doses induced significant improvement (P less than 0.005) in all 24 patients studied, transitory mental aberrations in seven, and release of growth hormone in three patients tested. In patients previously on prolonged levodopa administration, the dyskinesia and "on-off" phenomenon were almost identical with N-propylnoraporphine, but both drawbacks were reduced or abolished in six patients by coadministration of alpha-methyldopa hydrazine plus levodopa. This coadministration seemed to abolish tachyphylaxis. We conclude that N-propylnoraporphine is very useful in the treatment of Parkinson's disease.

Use of 6-hydroxydopamine to create lesions in catecholamine neurons in rats

The authors report experiments in rats with 6-hydroxydopamine (6-OHDA), a chemical agent used for creating lesions in catecholamine neurons. Stereotaxic injection of 6-OHDA into the compact zone of the substantia nigra induced degeneration of the nigrostriatal dopamine (DA) system, confirmed by histology and histochemistry of the substantia nigra and by dopamine determinations in the neostriatum. These observations closely mimic those found in Parkinson's disease. In the experimental model a rotatory behavior is induced by DA agonists; this response has been used to test drugs for potential therapeutic use and also in basic studies of the extrapyramidal system. This technique may be useful in developing other experimental models for neurosurgical problems involving catecholamine pathways.

Diphenylhydantoin. Blocking of levodopa effects

Diphenylhydantoin (DPH) diminished the therapeutic effects of levodopa both in patients with parkinsonism and in patients with chronic manganese poisoning, as well as the levodopa-dependent dyskinesia for which the former were selected. In patients with Huntington chorea, it enhanced chorea and mental agitation and, thus, failed to conform with the postulated pharmacological reciprocity between Parkinson disease and Huntington chorea. These findings are in agreement with experiments done in animals in which DPH blocked a neuronal response to dopamine.