N-Cadherin mRNA Levels in Peripheral Blood Could Be a Potential Indicator of New Metastases in Breast Cancer: A Pilot Study

Estradiol-Induced Epithelial to Mesenchymal Transition and Migration Are Inhibited by Blocking c-Src Kinase in Breast Cancer Cell Lines

PURPOSE

The epithelial-to-mesenchymal transition (EMT) is the main event that favors cell migration and metastasis in breast cancer. Previously, we demonstrated that 1 nM estradiol (E2) promotes EMT, induced by c-Src kinase, causing changes in the localization of proteins that compose the tight junction (TJ) and adherens junction (AJ).

METHODS

The present work highlights the central role of c-Src in the initiation of metastasis, induced by E2, through increasing the ability of MCF-7 and T47-D cells, which express estrogen receptor alpha (ERα), to migrate and invade before they become metastatic.

RESULTS

Treatment with E2 can activate two signaling pathways, the first one by the phosphorylated c-Src (p-Src) which forms the p-Src/E-cadherin complex. This phenomenon was completely prevented by incubation with a selective inhibitor of c-Src (5 µM PP2). p-Src then promotes the downregulation of E-cadherin and occludin, which are epithelial phenotype marker proteins of the AJ and TJ, respectively. In the second pathway, E2 binds to ERα, creating a complex that translocates to the nucleus, inducing the synthesis of SNAIL1 and N-cadherin proteins, markers of the mesenchymal phenotype. Both processes increased the migratory and invasive capacities of both cell lines.

CONCLUSION

The present study demonstrate that E2 enhance EMT and migration, through c-Src activation, in human breast cancer cells that express ERα and become potential therapeutic targets.

Downregulation of the paired box gene 3 inhibits the progression of skin cutaneous melanoma by inhibiting c-MET tyrosine kinase : PAX3 downregulation inhibits melanoma progression

BACKGROUND

The PAX3 (paired box gene 3) gene is highly expressed in several cancer types. However, its underlying mechanism of action in skin cutaneous melanoma (SKCM) remains unknown.

METHODS

In this study, we used the GEPIA database and western blotting to analyze the expression of PAX3. We performed the Kaplan-Meier survival analysis to evaluate the prognostic value of PAX3 in SKCM. Next, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was performed to evaluate the function of PAX3-related co-expressed genes. Additionally, the function and potential mechanism of action of PAX3 in SKCM were studied through functional experiments. Western blotting was used to detect the changes in the levels of epithelial-mesenchymal transition (EMT)-related and MET (c-MET tyrosine kinase) proteins following PAX3 knockdown. Finally, we assessed the correlation between PAX3 expression and the infiltration of CD4⁺/CD8⁺ T cells using the TISIDB database.

RESULTS

We found that PAX3 was overexpressed in the SKCM tissues and that these levels were indicative of a poor prognosis of SKCM. The KEGG pathway enrichment analysis showed that PAX3-related co-expressed genes were mainly associated with the oncogenic pathways. Knocking down PAX3 significantly inhibited the proliferation, invasion, and migration of SK-MEL-28 cells. The PAX3 expression was related significantly to the immune infiltration level of CD4⁺/CD8⁺ T cells.

CONCLUSIONS

Our findings demonstrated that PAX3 knockdown could reverse the EMT of tumor cells, inhibit the growth, and progression of SKCM cells. Therefore, PAX3 may have implications as a potential therapeutic target and promising prognostic biomarker for SKCM.

Proteomics and its applications in breast cancer

Breast cancer is an individually unique, multi-faceted and chameleonic disease, an eternal challenge for the new era of high-integrated precision diagnostic and personalized oncomedicine. Besides traditional single-omics fields (such as genomics, epigenomics, transcriptomics and metabolomics) and multi-omics contributions (proteogenomics, proteotranscriptomics or reproductomics), several new "-omics" approaches and exciting proteomics subfields are contributing to basic and advanced understanding of these "multiple diseases termed breast cancer": phenomics/cellomics, connectomics and interactomics, secretomics, matrisomics, exosomics, angiomics, chaperomics and epichaperomics, phosphoproteomics, ubiquitinomics, metalloproteomics, terminomics, degradomics and metadegradomics, adhesomics, stressomics, microbiomics, immunomics, salivaomics, materiomics and other biomics. Throughout the extremely complex neoplastic process, a Breast Cancer Cell Continuum Concept (BCCCC) has been modeled in this review as a spatio-temporal and holistic approach, as long as the breast cancer represents a complex cascade comprising successively integrated populations of heterogeneous tumor and cancer-associated cells, that reflect the carcinoma's progression from a "driving mutation" and formation of the breast primary tumor, toward the distant secondary tumors in different tissues and organs, via circulating tumor cell populations. This BCCCC is widely sustained by a Breast Cancer Proteomic Continuum Concept (BCPCC), where each phenotype of neoplastic and tumor-associated cells is characterized by a changing and adaptive proteomic profile detected in solid and liquid minimal invasive biopsies by complex proteomics approaches. Such a profile is created, beginning with the proteomic landscape of different neoplastic cell populations and cancer-associated cells, followed by subsequent analysis of protein biomarkers involved in epithelial-mesenchymal transition and intravasation, circulating tumor cell proteomics, and, finally, by protein biomarkers that highlight the extravasation and distant metastatic invasion. Proteomics technologies are producing important data in breast cancer diagnostic, prognostic, and predictive biomarkers discovery and validation, are detecting genetic aberrations at the proteome level, describing functional and regulatory pathways and emphasizing specific protein and peptide profiles in human tissues, biological fluids, cell lines and animal models. Also, proteomics can identify different breast cancer subtypes and specific protein and proteoform expression, can assess the efficacy of cancer therapies at cellular and tissular level and can even identify new therapeutic target proteins in clinical studies.

Association of the Epithelial-Mesenchymal Transition (EMT) with Cisplatin Resistance

Therapy resistance is a characteristic of cancer cells that significantly reduces the effectiveness of drugs. Despite the popularity of cisplatin (CP) as a chemotherapeutic agent, which is widely used in the treatment of various types of cancer, resistance of cancer cells to CP chemotherapy has been extensively observed. Among various reported mechanism(s), the epithelial–mesenchymal transition (EMT) process can significantly contribute to chemoresistance by converting the motionless epithelial cells into mobile mesenchymal cells and altering cell–cell adhesion as well as the cellular extracellular matrix, leading to invasion of tumor cells. By analyzing the impact of the different molecular pathways such as microRNAs, long non-coding RNAs, nuclear factor-κB (NF-ĸB), phosphoinositide 3-kinase-related protein kinase (PI3K)/Akt, mammalian target rapamycin (mTOR), and Wnt, which play an important role in resistance exhibited to CP therapy, we first give an introduction about the EMT mechanism and its role in drug resistance. We then focus specifically on the molecular pathways involved in drug resistance and the pharmacological strategies that can be used to mitigate this resistance. Overall, we highlight the various targeted signaling pathways that could be considered in future studies to pave the way for the inhibition of EMT-mediated resistance displayed by tumor cells in response to CP exposure.