The role of exosomal microRNAs; focus on clinical applications in breast cancer

Despite several advances in targeted therapies for breast cancer, breast-cancer-associated death remains high in women. This is partially due to the lack of reliable markers predicting metastatic disease or recurrence after initial therapy. Recent research into the clinical validity of circulating cancer-specific biomarkers as a “liquid biopsy” is of growing interest. Of these, exosomal microRNAs (miRNAs) are promising candidate biomarkers for clinical use in breast cancer. In addition to their diagnostic value, exosomal miRNAs play an important role in predicting clinical outcome or treatment response. In this review, it is focused on the findings concerning exosomal miRNAs in relation to disease detection, prognostic impact and therapeutic effect in breast cancer, and discuss their clinical utility

Genetic and environmental factors and serum hormones, and risk of estrogen receptor-positive breast cancer in pre- and postmenopausal Japanese women

Breast cancer incidence in Japanese women has more than tripled over the past two decades. We have previously shown that this marked increase is mostly due to an increase in the estrogen receptor (ER)-positive, HER2-negative subtype. We conducted a case-control study; ER-positive, HER2-negative breast cancer patients who were diagnosed since 2011 and women without disease were recruited. Environmental factors, serum levels of testosterone and 25-hydroxyvitamin D, and common genetic variants reported as predictors of ER-positive breast cancer or found in Asian women were evaluated between patients and controls in pre-and postmenopausal women. To identify important risk predictors, risk prediction models were created by logistic regression models. In premenopausal women, two environmental factors (history of breastfeeding, and history of benign breast disease) and four genetic variants (TOX3-rs3803662, ESR1-rs2046210, 8q24-rs13281615, and SLC4A7-rs4973768) were considered to be risk predictors, whereas three environmental factors (body mass index, history of breastfeeding, and hyperlipidemia), serum levels of testosterone and 25-hydroxyvitamin D, and two genetic variants (TOX3-rs3803662 and ESR1-rs2046210) were identified as risk predictors. Inclusion of common genetic variants and serum hormone measurements as well as environmental factors improved risk assessment models. The decline in the birthrate according to recent changes of lifestyle might be the main cause of the recent notable increase in the incidence of ER-positive breast cancer in Japanese women

Clinical significance of plasma cell-free DNA mutations in PIK3CA, AKT1, and ESR1 gene according to treatment lines in ER-positive breast cancer

Abstract The somatic activation of PI3K/AKT pathway mutations, PIK3CA and AKT1, and ESR1 mutations in plasma cell-free DNA (cfDNA) has been studied as a non-invasive procedure to quickly assess and monitor disease progression or therapeutic effect in breast cancer (BC) patients, but the clinical significance of these mutations in late treatment lines (TLs) remains unclear. The subjects of this study were a total of 251 plasma samples from 128 estrogen receptor-positive (ER+) BC patients. Of these plasma samples, 133 were from 73 primary BC (PBC) patients, and 118 plasma samples were from 68 metastatic BC (MBC) patients. We developed droplet digital PCR (ddPCR) assays to verify the clinical significance of PIK3CA, AKT1, and ESR1 mutations in these patients. cfDNA PIK3CA mutations were observed in 15.1% of the PBC patients, while a cfDNA AKT1 mutation was observed in 1.4% of patients, and cfDNA ESR1 mutations were observed in 2.7% of patients. Patients with detectable cfDNA PIK3CA mutations were not associated with clinical outcomes. According to the TL, the prevalence of the PIK3CA and ESR1 mutations in cfDNA were lower in early TLs compared with late TLs. In the early TL group, patients with cfDNA PIK3CA mutations had a shorter time to treatment failure (TTF) than patients without mutations (P = 0.035). However, there was no statistically significant difference between patients with or without cfDNA ESR1 mutations. However, in the late TL group, patients with cfDNA ESR1 mutations had a shorter TTF than patients without mutations (P = 0.048). However, there was no statistically significant difference between patients with or without cfDNA PIK3CA mutations. Since the prevalence of cfDNA AKT1 mutation is low in both PBC and MBC patients, the impact of AKT1 mutations on the prognosis remains unclear. We have demonstrated the difference in the clinical significance of the hotspot PIK3CA, AKT1, and ESR1 mutations in cfDNA for each TL in ER+ BC patients

Prevalence of ESR1 E380Q mutation in tumor tissue and plasma from Japanese breast cancer patients

Abstract Background ESR1 mutations have attracted attention as a potentially important marker and treatment target in endocrine therapy-resistant breast cancer patients. The E380Q mutation, which is one of the ESR1 mutations, is associated with estradiol (E2) hypersensitivity, increased DNA binding to the estrogen response element, and E2-independent constitutive trans-activation activity, but its frequency in ESR1 mutations remains unknown. The present study aimed to investigate the E380Q mutation in comparison with the other representative ESR1 mutations. Methods We screened a total of 62 patients (66 tumor tissues and 69 plasma cell-free DNA (cfDNA)) to detect ESR1 mutations (E380Q, Y537S, Y537N, Y537C, and D538G) using droplet-digital polymerase chain reaction. Plasma was collected at more than two points of the clinical course, in whom changes of ESR1 mutations under treatment were investigated. Results We detected ESR1 mutations in 21% (12/57) of MBCs. The E380Q ESR1 mutation was found in 16% (2/12) and the other ESR1 LBD mutations were five (41.6%) of Y537S, and four each (33.3%) of D538G, Y537N, and Y537C, in 12 ESR1 mutant breast cancer patients. Five tumors had multiple ESR1 mutations: three had double ESR1 mutations; Y537S/E380Q, Y37S/Y537C, and Y537S/D538G, and two had triple ESR1 mutations; Y537S/Y537N/D538G. In plasma cfDNA analysis, the E380Q mutation was not detected, but increases in other ESR1 mutations were detected in 46.2% (6/13) of MBC patients under treatment. Conclusions We have shown that there are distinct populations of ESR1 mutations in metastatic tissue and plasma. Each ESR1 mutation may have different clinical significance, and it will be necessary to investigate them all

Immunohistochemical staining patterns of PTEN, pAkt, and INPP4B. pAkt expression; A, negative staining (HS<12.5), B, positive (HS≥12.5), PTEN expression; C, negative staining (HS<60), D, positive (HS≥60), INPP4B expression; E, negative staining (HS<60), F, positive (HS≥60) (Magnification ×400).

<p>Immunohistochemical staining patterns of PTEN, pAkt, and INPP4B. pAkt expression; A, negative staining (HS<12.5), B, positive (HS≥12.5), PTEN expression; C, negative staining (HS<60), D, positive (HS≥60), INPP4B expression; E, negative staining (HS<60), F, positive (HS≥60) (Magnification ×400).</p

Detection of <i>PIK3CA</i> mutation (E542K, E545K, H1047R) by DNA sequencing and digital PCR analysis (only among the patients whose mutations were detected).

a<p>Frequency of the patient with mutated DNA.</p><p>Detection of <i>PIK3CA</i> mutation (E542K, E545K, H1047R) by DNA sequencing and digital PCR analysis (only among the patients whose mutations were detected).</p

Patients characteristics and treatment response by <i>PIK3CA</i> mutation, copy number variation, PTEN, pAkt, and INPP4B expression.

<p>WT; wild type, ER; estrogen receptor, PR; progesteron receptor, HER2; human epidermal growth factor 2, PTEN; phosphatase and tensin homolog, INPP4B; inositol polyphosphate 4-phosphatase-II,</p>a<p>Mutation was defind as positive if the proportion of mutant DNA was more than 10% by digital PCR analysis.</p>b<p>copy number gain was defiend if the copy number of <i>PIK3CA</i> was greater than 1.5 compared to <i>RNaseP</i>.</p><p>Patients characteristics and treatment response by <i>PIK3CA</i> mutation, copy number variation, PTEN, pAkt, and INPP4B expression.</p

Correlation of proportion of <i>PIK3CA</i> mutation (defined by digital PCR) with the pCR rate.

<p>Mut; mutation, WT; wild type.</p