Genetic Determinants of Aggressive Breast Cancer

Identification of novel genetic and epigenetic regulators of different tissue types of cervical cancer

OBJECTIVES

The study aimed to find differential gene mutations, DNA methylation, and expression profiles among different categories of cervical cancer samples.

METHODS

The study was based on freely available gene mutations, promoter methylation, and gene expression status of The Cancer Genome Atlas (TCGA) cervical cancer samples and adjacent normal tissues in the Genomic Data Commons (GDC) portal. The association of CpG island methylation with gene expression was determined through negative correlation analysis.

RESULTS

We identified that the ErbB signaling pathway and proteoglycans pathway was significantly associated with adenocarcinoma cervical cancers patients. In these pathways, missense mutation especially S310F in the ERBB2 gene as well as G12D and A146T in the KRAS gene were significantly associated with adenocarcinoma cases. Furthermore, a comparison of SCC cases with adjacent control tissues revealed differential hypermethylation of two CpG positions of the KAAG1 gene and differential downregulation of NPY1R and NPY5R genes in cervical squamous cell carcinoma compared to cervical adenocarcinoma cases and adjacent normal tissues. Specifically, the hypermethylation of the promoter region of the KAAG1 gene might be responsible for the carcinogenesis of cervical squamous cells exclusively and methylation marks can be reversible by the widely used drug, azacytidine. In contrast, adenocarcinoma cervical cancer cases may be treated with floxuridine which is successfully utilized for other tissue-specific adenocarcinoma cases.

CONCLUSIONS

These results provide valuable insight into the differential molecular markers among the categories of cervical cancer, which helps our ability to classify these cancers and for targeted therapy.

PDL1 expression in inflammatory breast cancer is frequent and predicts for the pathological response to chemotherapy

We retrospectively analyzed PDL1 mRNA expression in 306 breast cancer samples, including 112 samples of an aggressive form, inflammatory breast cancer (IBC). PDL1 expression was heterogeneous, but was higher in IBC than in non-IBC. Compared to normal breast samples, PDL1 was overexpressed in 38% of IBC. In IBC, PDL1 overexpression was associated with estrogen receptor-negative status, basal and ERBB2-enriched aggressive subtypes, and clinico-biological signs of anti-tumor T-cell cytotoxic response. PDL1 overexpression was associated with better pathological response to chemotherapy, independently of histo-clinical variables and predictive gene expression signatures. No correlation was found with metastasis-free and overall specific survivals. In conclusion, PDL1 overexpression in IBC correlated with better response to chemotherapy. This seemingly counterintuitive correlation between expression of an immunosuppressive molecule and improved therapeutic response may be resolved if PDL1 expression is viewed as a surrogate marker of a strong antitumor immune response among patients treated with immunogenic chemotherapy. In such patients, PDL1 inhibition could protect activated T-cells or reactivate inhibited T-cells and improve the therapeutic response, notably when associated with immunogenic chemotherapy.

Molecular markers for breast cancer: prediction on tumor behavior

Breast cancer is one of the most common cancers with greater than 1,300,000 cases and 450,000 deaths each year worldwide. The development of breast cancer involves a progression through intermediate stages until the invasive carcinoma and finally into metastatic disease. Given the variability in clinical progression, the identification of markers that could predict the tumor behavior is particularly important in breast cancer. The determination of tumor markers is a useful tool for clinical management in cancer patients, assisting in diagnostic, staging, evaluation of therapeutic response, detection of recurrence and metastasis, and development of new treatment modalities. In this context, this review aims to discuss the main tumor markers in breast carcinogenesis. The most well-established breast molecular markers with prognostic and/or therapeutic value like hormone receptors, HER-2 oncogene, Ki-67, and p53 proteins, and the genes for hereditary breast cancer will be presented. Furthermore, this review shows the new molecular targets in breast cancer: CXCR4, caveolin, miRNA, and FOXP3, as promising candidates for future development of effective and targeted therapies, also with lower toxicity.

On how CCN6 suppresses breast cancer growth and invasion

Living cells communicate with their microenvironment and exchange information through signaling pathways in order to carry out most biological processes. The CCN family of proteins has the ability to coordinate the extracellular and intracellular signaling pathways and epithelial-stromal cross-talks. CCN proteins have been shown to play roles in multiple processes including cancer, either as tumor suppressors or oncogenes. Particularly, loss of CCN6 expression has been reported in highly aggressive breast cancer types, especially in inflammatory breast cancer and breast cancer with axillary lymph node metastasis. Recent findings can better explain the biological relevance of CCN6 as a tumor suppressor protein in breast tumorigenesis. CCN6 loss triggers the process of epithelial to mesenchymal transition (EMT), which converts epithelial cells into migratory and invasive mesenchymal-like cells at least in part through modulation of IGF-1 receptor signaling pathway. Emerging data support the hypothesis that CCN6 also exerts growth factor independent functions, especially related to cell survival and anoikis resistance. Thus, our work provides new insights into the functions and mechanisms of tumor suppression exerted by CCN6 in the breast.

GPR30 and estrogen receptor expression: new insights into hormone dependence of inflammatory breast cancer

GPR30 is a novel G protein-coupled estrogen receptor (ER) associated with metastases in breast cancer (BC) and poor survival in endometrial and ovarian tumors. The association of GPR30 expression with inflammatory breast cancer (IBC), an aggressive and commonly hormone-independent form of BC, has not been studied. GPR30, ER, progesterone receptor (PR), epidermal growth factor receptor (EGFR), and HER-2 expression were assessed by immunohistochemistry (and FISH for HER-2) in 88 primary IBCs. GPR30 expression was correlated with patient overall survival (OS), disease-free survival (DFS), pathologic variables, and other biomarkers. GPR30 expression was found in 69% of IBC cases. ER, PR, HER-2, and EGFR were found in 43, 35, 39, and 34% of IBC cases, respectively. GPR30 expression correlated inversely with ER expression (P = 0.02). Co-expression of ER and GPR30 was found in 24% of IBC samples; 19% expressed only ER and 46% expressed only GPR30. Univariate analysis showed no association between GPR30 expression and OS or DFS. However, co-expression of ER and GPR30 was associated with improved OS (P < 0.03) and marginally with DFS (P < 0.06); the absence of both ER and GPR30 was associated with worse OS and DFS (P = 0.03 for both). Multivariate analysis identified ER as an independent prognostic factor of OS (P = 0.008) and DFS (P = 0.02). The majority of IBC tumors are GPR30-positive, suggesting that estrogen signaling may be active in ER-negative IBC patients. These findings suggest potential new therapeutic targets for IBC such as novel endocrine agents or direct modulation of GPR30.

Physiological fluorescence lifetime imaging microscopy improves Förster resonance energy transfer detection in living cells

Accurate, unambiguous detection of molecular interactions in living cells via measurements of Forster (or fluorescence) resonance energy transfer (FRET) events is experimentally challenging. We develop and apply a physiological fluorescence lifetime imaging microscopy (physiological FLIM) system to significantly improve FRET detection in living cells. Multiple positive and negative cellular controls are implemented to validate the experimental method developed. FLIM measurement techniques were found to remove fluorescence intensity-based artifacts, resulting in a seven-fold improvement in fluorescence measurement precision. The addition of cellular environmental controls, including both temperature and CO(2) stabilization, for physiological FLIM eliminates nonspecific FRET in the live-cell system studied. Overall, only physiological FLIM results in statistically significant results that clearly indicated the presence of specific molecular interactions in the live-cell system. This approach can be applied generally to improve the accuracy and precision of FRET measurements in living cells.

Odontogenic Ameloblast Associated Protein as a Novel Biomarker for Human Breast Cancer

Odontogenic Ameloblast Associated Protein (ODAM) is a protein isolated in ameloblasts during odontogenesis. ODAM expression was identified in breast cancer, but its significance remains unknown. The purpose of this study is to determine if ODAM expression can serve as a prognostic marker and provide information regarding treatment in human breast cancer. Breast cancer patients were identified from our tumor registry from 1993 to 2003. Archived breast cancer tissue from 243 patients (stage 0 = 53, stage I = 51, stage II = 53, stage III = 47, stage IV = 39) was stained using monoclonal antibody for ODAM. Presence or absence of immunostaining was correlated with stage, histologic grade, response to chemotherapy, and survival using χ2 and logistic regression analyses. Tumor nuclear staining for ODAM increased with increasing group stage ( P < 0.001). Staining for ODAM did not correlate with histologic grade or chemotherapy ( P = 0.558, P = 0.093). Improved outcomes within each stage were noted with ODAM staining, statistically significant for stages 0, I, and II ( P < 0.001, P = 0.003, P = 0.003) and underpowered for stages III and IV ( P = 0.724, P = 0.059). Survival benefit associated with tumor nuclear staining increased with advancing stage ( P < 0.001). These results show that ODAM predicts survival in breast cancer. Research is ongoing to determine ODAM's clinical utility and role in carcinogenesis.

Anti-tumor activity of N-thiolated beta-lactam antibiotics

An ongoing strategy for cancer treatment is selective induction of apoptosis in cancer over normal cells. N-thiolated beta-lactams were found to induce DNA damage, growth arrest and apoptosis in cultured human cancer cells. However, whether these compounds have a similar effect in vivo has not been studied. We report here that treatment with the beta-lactam L-1 caused a significant inhibition of tumor growth in a breast cancer xenograft mouse model, associated with induction of DNA damage and apoptosis in vivo. These results suggest that the synthetic antibiotic N-thiolated beta-lactams hold great potential to be developed as novel anti-cancer drugs.