Attualità in Senologia

Rassegna della letteratura – aprile/giugno 2020
Biologia, genetica e fattori prognostici 

The differences of clinicopathologic characteristics among subgroups of reclassified HER2 fluorescence in situ hybridization (FISH) according to the ASCO/CAP 2018 breast cancer HER2 testing guidelines – Libo Yang , Min Chen et Al –  J Clin Pathol . 2020 May;73(5):283-290.

Aims: The aim of this study is to analyse differences in clinicopathologic features among reclassified human epidermal growth factor receptor-2 (HER2) fluorescence in situ hybridization (FISH) results in breast cancers according to 2018 guidelines.

Methods: According to different ratios of HER2 copy numbers to chromosome 17 centromere numbers (HER2/CEP17) and average HER2 copy numbers, 3795 invasive breast cancers were classified into six groups. Clinicopathologic features were collected and compared among different FISH groups.

Results: There were no statistically significant differences about HER2 positive rate between 2013 and 2018 guidelines (p=0.518). After re-evaluating these cases according to 2018 guidelines, the cases that converted to a HER2 positive status had clinicopathologic features similar to samples in group 1 (ratio ≥2.0, HER2 ≥4.0). Compared with group 5 (ratio <2.0, HER2 <4.0), the cases in groups 1 had higher histological grade, more frequent occurrence of negative oestrogen receptor and progesterone receptor status and a higher Ki67 index. The samples in group 4 (ratio <2.0, 4.0≤HER2<6.0) showed a higher histological grade and higher Ki67 index than did the samples in group 5 but had a lower histological grade and lower Ki67 index than did the samples in group 1a (ratio ≥2.0, HER2 ≥6.0).

Conclusion: Different categories of HER2 FISH test results have significant differences in clinicopathologic features. With no equivocal cases in 2018 HER2 guidelines, the clear division of HER2 status is helpful for making treatment recommendations about HER2 targeted therapy.

The genomic landscape of metastatic breast cancer: Insights from 11,000 tumors Jacob Rinaldi , Ethan S Sokol, Ryan J Hartmaier et Al. – PLoS One. 2020 May 6;15(5):e0231999.

Background: Metastatic breast cancer is the leading cause of cancer death in women, but the genomics of metastasis in breast cancer are poorly studied.

Methods: We explored a set of 11,616 breast tumors, including 5,034 metastases, which had undergone targeted sequencing during standard clinical care.

Results: Besides the known hotspot mutations in ESR1, we observed a metastatic enrichment of previously unreported, lower-prevalence mutations in the ligand-binding domain, implying that these mutations may also be functional. Furthermore, individual ESR1 hotspots are significantly enriched in specific metastatic tissues and histologies, suggesting functional differences between these mutations. Other alterations enriched across all metastases include loss of function of the CDK4 regulator CDKN1B, and mutations in the transcription factor CTCF. Mutations enriched at specific metastatic sites generally reflect biology of the target tissue and may be adaptations to growth in the local environment. These include PTEN and ASXL1 alterations in brain metastases and NOTCH1 alterations in skin. We observed an enrichment of KRAS, KEAP1, STK11 and EGFR mutations in lung metastases. However, the patterns of other mutations in these tumors indicate that these are misdiagnosed lung primaries rather than breast metastases.

Conclusions: An order-of-magnitude increase in samples relative to previous studies allowed us to detect novel genomic characteristics of metastatic cancer and to expand and clarify previous findings.

MicroRNA‑34a expression affects breast cancer invasion in vitro and patient survival via downregulation of E2F1 and E2F3 expression Rui HanJing ZhaoLingeng Lu ET Al – Oncol Rep . 2020 Jun;43(6):2062-2072.

Breast cancer is the most common cancer type and the leading cause of cancer‑associated mortality in women across the majority of countries. In general, the incidence of breast cancer has been decreasing in developed countries over the previous 20 years, while it has increased in the other areas, such as the Asian‑Pacific region. MicroRNA‑34a (miR‑34a) targets stem cell‑associated transcription factors E2F1/E2F3, and may have clinical relevance in breast cancer. The present study aimed to investigate the association between miR‑34a/E2F1/E2F3 and patient survival in breast cancer, as well as the underlying molecular mechanism of miR‑34a in suppressing factors associated with tumor aggressiveness in vitro. Kaplan‑Meier survival curves were constructed and a meta‑analysis was performed to analyze the association of miR‑34a, E2F1 and E2F3 expression and overall survival in breast cancer, and the differential expression levels of E2F1 and E2F3 between breast cancer and normal breast tissues was assessed using publicly accessed datasets. Then 2D and 3D experiments on cell cultures were performed in vitro on both T‑47D and MDA‑MB‑231 cells to investigate the cancer biology of miR‑34a and its effect on E2F1 and E2F3 expression using reverse transcription‑quantitative PCR. Then, caspase‑3 (CASP3) activity was measured using a CaspACE™ assay system. E2F1 and E2F3 expression levels were upregulated in breast cancer, compared with normal breast tissues. Both high miR‑34a, and low E2F1 and E2F3 mRNA levels were positively associated with longer survival times in patients with breast cancer. The in vitro 2D and 3D cell experiments revealed that overexpression of miR‑34a significantly downregulated the expression of E2F1 and E2F3, and increased CASP3 activity in both T‑47D and MDA‑MB‑231 cells, and that miR‑34a treatment inhibited tumor cell proliferation, migration and invasiveness, as well as 3D spheroid formation. Thus, miR‑34a influences the aggressiveness of breast cancer and patient survival, and is a potential therapeutic tool in the clinical management of breast cancer.

A functional variant near XCL1 gene improves breast cancer survival via promoting cancer immunity. Wen-Cheng Chou  , Chia-Ni Hsiung et Al. / Int J Cancer . 2020 Apr 15;146(8):2182-2193.

Most genome-wide association studies (GWASs) identify genetic variants for breast cancer occurrence. In contrast, few are for recurrence and mortality. We conducted a GWAS on breast cancer survival after diagnosis in estrogen receptor-positive patients, including 953 Taiwanese patients with 159 events. Through Cox proportional hazard models estimation, we identified 24 risk SNPs with p < 1 × 10-5 . Based on imputation and integrated analysis, one SNP, rs1024176 (located in 1q24.2, p = 2.43 × 10-5 ) was found to be a functional variant associated with breast cancer survival and XCL1 gene expression. A series of experimental approaches, including cell-based analyses and CRISPR/Cas9 genome-editing system, were then used and identified the transcription factor MYBL2 was able to discriminately bind to the A allele of rs1024176, the protective variant for breast cancer survival, which promoted XCL1 expression, but not to the G allele of rs1024176. The chemokine XCL1 attracts type 1 dendritic cells (DC1s) to the tumor microenvironment. In breast cancer tissues, we applied a two-step Mendelian randomization analysis, using expression quantitative trait loci as instrumental variables, to confirm higher XCL1 expression was correlated with higher DC1 signatures and favorable disease progression, through the causal effect of rs1024176-A allele. Our study supports the genetic effect on preventing breast cancer survival through XCL1-induced DC1 recruitment in tumor microenvironment.

Bruna Cerbelli , Andrea Botticelli Annalinda Pisano et Al. – Virchows Arch . 2020 Apr;476(4):569-576

The immune system plays a key role in tumor surveillance and escape. Recently, CD73 has been proposed as a prognostic biomarker associated with disease-free survival and overall survival in triple negative breast cancer (TNBC). In this study, we investigated the role of both CD73 expression and stromal tumor-infiltrating lymphocytes (TILs) in predicting the pathologic response of TNBC to neoadjuvant chemotherapy (NACT). We retrospectively analyzed CD73 immunohistochemical expression and stromal TILs on 61 consecutive biopsies from patients who received standard NACT. Twenty-three patients (38%) achieved pathologic complete response (pCR). TILs were present in the majority of biopsies (93%) with percentages ranging from 2 to 80%. High TILs (≥ 50%) were found in 30% of cases, and in this group, pCR was achieved in 76.5% of cases. Levels of TILs were associated with a better pathologic response only at univariate analysis (p = 0.037). The median value of CD73 expression on tumor cells was 40%. In 32 (52.5%) basal biopsies, CD73 expression was below or equal to median value (“low CD73”). A pCR was obtained in 53% of cases with “low CD73” and in 21% with high CD73, and this was statistically different both at univariate (p = 0.011) and multivariate (p = 0.014) analysis.Our results suggest that CD73 expression better predicts the response to NACT than TILs in TNBC. Characterization of both TILs and microenvironment could be a promising approach to personalize treatment.

Role of regulatory miRNAs of the PI3K/AKT signaling pathway in the pathogenesis of breast cancer. Farzad Rahmani  , Gordon A Ferns  , Sahar Talebian et Al. – Gene . 2020 May 5;737:144459.

Breast cancer is one of the most common tumors in women. Current data indicate that the overexpression of some microRNAs (miRNAs) is associated with breast cancer, in relation to stage, tumor size and potential for metastasis. Some studies have reported that miRNAs have critical roles in cellular processes implicated in breast cancer cell growth, migration and metastasis by targeting the PI3K/AKT oncogenic signaling pathway. Therefore, identifying novel regulatory miRNAs for this oncogenic pathway and discovery of their related target genes may represent a promising therapeutic approach for breast cancer therapy. This review highlights the recent findings about the potential role of PI3K/AKT signaling regulatory miRNAs in breast cancer tumorigenesis