Expression of WTH3 in breast cancer tissue and the effects on the biological behavior of breast cancer cells

Salivary DNA methylation markers for cancer of oral cavity

PURPOSE: Aberrant DNA methylation plays a crucial role in oral carcinogenesis. Our previous study demonstrated hypermethylation of DAPK1, LRPPRC, RAB6C, and ZNF471 promoters in patients with tongue squamous cell carcinoma compared with normal samples. Methylation profiling using salivary DNA is considered a non-invasive alternative to tissue samples. Hence, the present study tested the DNA methylation status of these four promoters as indicators of oral cancer progression. METHODS: We performed the bisulfite-based targeted next-generation sequencing of four candidate genes in saliva and tissue DNA from normal, premalignant, and squamous cell carcinoma subjects. The clinicopathological association, diagnostic, and prognostic utility of aberrant DNA methylation were evaluated using the TCGA-HNSCC dataset. Using the Xgboost algorithm and logistic regression, CpG sites were prioritized, and Receiver Operating Characteristic was generated. By Log-rank test and Kaplan-Meier (KM) curves, an association between methylation and overall survival (OS), disease-free interval (DFI), and progression-free interval (PFI) were computed. RESULTS: We identified all four genes as significantly hypermethylation in premalignant and malignant samples compared with normal samples. The methylation levels were comparable between saliva and tissue samples with an r-value of 0.6297 to 0.8023 and 0.7823 to 0.9419 between premalignant tissue vs. saliva and OC vs. saliva, respectively. We identified an inverse correlation between DAPK1, LRPPRC, RAB6C, and ZNF471 promoter methylation with its expression. A classifier of 8 differentially methylated CpG sites belonging to DAPK1, RAB6C, and ZNF471 promoters was constructed, showing an AUC of 0.984 to differentiate tumors from normal samples. The differential methylation status of DAPK1, LRPPRC, and ZNF71 promoters was prognostically important. Abnormal expression of all four genes was associated with immune infiltration. CONCLUSIONS: Thus, methylation analysis of these candidate CpG sites from saliva can be helpful as a non-invasive tool for the clinical management of OC.

Low RAB6C expression is a predictor of tamoxifen benefit in estrogen receptor-positive/progesterone receptor-negative breast cancer

Over the last few decades, improved and more individualized treatment has contributed to the increased survival rate of patients with breast cancer. However, certain patients may receive excessive treatment resulting in undesired side effects. In a previous study, it was demonstrated that systemically untreated patients with estrogen receptor (ER)-positive/progesterone receptor (PR)-negative tumors with high Ras-related protein Rab-6C (RAB6C) expression levels (RAB6C⁺) had prolonged distant recurrence-free survival compared with that of patients exhibiting low RAB6C (RAB6C^-)-expressing tumors. The aim of the present study was to investigate whether RAB6C predicts the effectiveness of tamoxifen treatment. The present study used a dataset comprising 486 female patients with ER⁺ tumors from a randomized study conducted by the Stockholm Breast Cancer Study Group between November 1976 and August 1990. The patients were considered as low-risk if their tumor size was ≤30 mm and their lymph node status was negative. Patients were followed up until distant recurrence, mortality or when 25 years after randomization was achieved, whichever occurred first. For patients with ER⁺/PR^-/RAB6C⁺ tumors, prolonged distant recurrence-free survival could not be observed if the patients were treated with tamoxifen [hazard ratio (HR), 1.82; 95% confidence interval (CI), 0.69-4.79; P=0.23], whereas patients with ER⁺/PR^-/RAB6C^- tumors had 75% reduced distant recurrence risk (HR, 0.25; 95% CI, 0.09-0.70; P=0.008). In the ER⁺/PR⁺ subgroup, patients with RAB6C^- and RAB6C⁺ tumors benefited from tamoxifen treatment, though it was most evident in the RAB6C⁺ group (HR, 0.27; 95% CI, 0.13-0.58; P=0.001). The results of the present study indicated that, for patients with ER⁺/PR^- tumors, those with low RAB6C expression benefited from tamoxifen treatment, whereas no benefit was observed in patients with high RAB6C levels.

RAB6C is an independent prognostic factor of estrogen receptor-positive/progesterone receptor-negative breast cancer

The majority of breast cancer tumors are estrogen receptor-positive (ER⁺) and can be treated with endocrine therapy. However, certain patients may exhibit a good prognosis without systemic treatment. The aim of the present study was to identify novel prognostic factors for patients with ER⁺ breast cancer tumors using gene copy data, and to investigate if these factors have prognostic value in subgroups categorized by progesterone receptor status (PR). Public data, including the whole genome gene copy data of 199 systemically untreated patients with ER⁺ tumors, were utilized in the present study. To assess prognostic value, patients were divided into two groups using the median gene copy number as a cut-off for the SNPs that were the most variable. One SNP was identified, which indicated that the Ras-related protein Rab-6C (RAB6C) gene may exhibit prognostic significance. Therefore, RAB6C protein expression was subsequently investigated in a second independent cohort, consisting of 469 systematically untreated patients (of which 310 were ER⁺) who received long term follow-up. In the public data set, a distant recurrence risk reduction of 55% was determined for copy numbers above the median value of RAB6C compared with numbers below [multivariable adjusted hazard ratio (HR), 0.45; 95% CI 0.28–0.72; P=0.001)]. It was also more pronounced in the ER⁺/PR⁻ subgroup (HR, 0.15; 95% CI, 0.05–0.46; P=0.001). In the second cohort, patients of the ER⁺/PR⁻ subgroup who exhibited high RAB6C expression had a reduced distant recurrence risk (HR, 0.17; 95% CI, 0.05–0.60; P=0.006). However, this was not identified among ER⁺/PR⁺ tumors (HR, 1.31; 95% CI, 0.69–2.48; P=0.41). The results of the present study indicated that RAB6C serves as an independent prognostic factor of distant recurrence risk in systemically untreated patients with an ER⁺/PR⁻ tumor.