Transition In Triple-negative Breast Cancer Cells Research Articles

Inhibition of endoplasmic reticulum stress alleviates triple-negative breast cancer cell viability, migration, and invasion by Syntenin/SOX4/Wnt/β-catenin pathway via regulation of heat shock protein A4

ABSTRACT Endoplasmic reticulum stress (ER stress) is a double-edged sword in the occurrence and development of malignant cancer. The aim of this study was to explore the roles of ER stress in metastasis and epithelial-mesenchymal transitionin triple-negative breast cancer (TNBC) and potential mechanisms. In this study, 4-PBA was administrated to inhibit the ER stress. Cell viability was evaluated using a cell counting kit-8 assay. Cell migration and invasion were identified by wound healing and transwell assay, respectively. Levels of MMP2 and MMP9 were measured by enzyme-linked immunosorbent assay and immunohistochemical staining. Western blot assay was used to assess the levels of ER stress-related proteins, Syndecan-1 (SDC-1)/Syntenin-1 (SDCBP-1)/SRY-related HMG-box 4 (SOX4) signaling and Wnt/β-catenin signaling. Moreover, a xenograft mice model was conducted to confirm the role of ER stress in TNBC. The data indicate that the ability of viability and metastasis of breast cancer cells were stronger than normal mammary epithelial cells. More aggressiveness was manifested in TNBC cells than that in non-TNBC cells. 4-PBA significantly suppressed the viability, migration, and invasion in BC cells and inhibited the SDC/SDCBP/SOX4 axis and Wnt/β-catenin signaling. Furthermore, heat shock protein A4 (HSPA4) overexpression stimulated ER stress and activated the SDC-1/SDCBP-1/SOX4 pathway and Wnt/β-catenin signaling. Animal experiments showed similar results that 4-PBA repressed tumor growth and inactivated the two pathways, while HSPA4 overexpression reversed the effects of 4-PBA. In summary, inhibition of ER stress inhibited TNBC viability, migration, and invasion by Syntenin/SOX4/Wnt/β-catenin pathway via regulation of HSPA4 in vivo and in vitro.

CD155 contributes to the mesenchymal phenotype of triple-negative breast cancer.

Patients with triple‐negative breast cancer (TNBC) lack molecular targets and have an unfavorable outcome. CD155 is overexpressed in human cancers, but whether it plays a role in TNBC is unexplored. Here we found that CD155 was enriched in both TNBC cell lines and tumor tissues. High CD155 expression was related to poor prognosis of breast cancer patients. CD155 was associated with a mesenchymal phenotype. CD155 knockdown induced a mesenchymal‐epithelial transition in TNBC cells, and suppressed TNBC cell migration, invasion and metastasis in vitro and in vivo. Mechanistically, CD155 cross‐talked with oncogenic IL‐6/Stat3 and TGF‐β/Smad3 pathways. Moreover, CD155 knockdown inhibited TNBC cell growth and survival. Taken together, these data indicate that CD155 contributes to the aggressive behavior of TNBC; targeting CD155 may be beneficial to these patients.

Anti-Tumor Effect of Cicer Arietinum against the Triple-Negative Breast Cancer Cells

Triple negative breast cancer (TNBC) is the most aggressive and deadly subtype of breast cancer. The only treatment option available for TNBC is conventional therapy, which associated with debilitating-side effects and drug-resistance. Therefore, using natural chemo-preventive agents to suppress cancer progression or reverse its initiation is an effective and safe way in cancer therapy. The aim of this study was to investigate the antitumor effect of Cicer arietinum (CAE) in vitro employing TNBC cell lines MDA-MB-231 and 4T1. Cell viability, Colony formation as readout for single cell ability to form a colony, gelatin-cell adhesion, and immunofluorescence staining were used to assessthat effect. Relative to control cells, our results indicate that CAE treatment significantly decreased cell viability, colony formation, and cell adhesion. Intriguingly, immunofluorescence microscopy unveiled that TNBC cells exhibited an attenuation of the constitutive and EGF-induced p44/42 MAPK signaling pathway implicated in regulating cell survival. Moreover, a morphological transition of TNBC cells from a fibroblast-like spindle-shaped into epithelial-like cells was observed. In conclusion, CAE may emerge as a promising antitumor agent against TNBC possibly via attenuation of EGF-induced p44/42 MAPK signaling.

Abstract 4190: Synergistic anticancer effect of sulforaphane and cisplatin on sirtuins-mediated epithelial-to-mesenchymal signaling in triple negative breast cancer

Abstract Purpose: Triple negative breast cancer (TNBC) overexpresses sirtuins (SIRTs), a class III HDACs, which induces epithelial-to-mesenchymal (EMT) transition and facilitates Cisplatin (CIS) resistance. We hypothesized that Sulforaphane (SFN), an HDAC inhibitor, when combined with CIS, could potentiate CIS efficacy against TNBC metastasis and overcome its resistance. Material and Methods: The effect of SFN and CIS combination on cellular proliferation and apoptosis of two TNBC cell lines, MDA-MB-231 and MDA-MB-468 were assessed by MTT assay and Annexin and PI method followed by FACS analysis respectively. The anti-metastatic capabilities of the compounds were evaluated using wound healing assay, invasion assay, chemotaxis assay, colony formation and tumorsphere assay. The regulation of key proteins involved in sirtuin-mediated EMT signaling and metastasis was determined by zymography and western blot analysis. Results: The results revealed that SFN in combination with CIS synergistically inhibited TNBC cells through inhibition of cellular proliferation, induction of apoptosis, in-silico and in-vitro modulation of SIRTs (1-7) expression. Anti-metastatic capabilities of the combinatorial treatment regimen were associated with inhibition of migratory, invasive, mammosphere forming potential and downregulation of matrix metallopeptidase (MMP-9 and MMP-2) activity of TNBC cells. When TNBC cells were treated with SFN, the expression of epithelial marker, E-cadherin was up-regulated, while the expression of mesenchymal markers, ZEB1, SNAIL, TWIST and associated SIRTs were down-regulated. In contrast, when the cells were treated with CIS, the expressions of mesenchymal markers were up-regulated. Interestingly, the combinatorial treatment of SFN and CIS synergistically inhibited EMT transition in TNBC cells. In-vivo studies are warranted to confirm our results. Conclusion: Collectively our findings demonstrated a SIRTs-mediated EMT-suppression leading to synergistic antitumor effect by combination of SFN and CIS in TNBC cells. This combination therapy may serve as a novel therapeutic strategy for TNBC management. Citation Format: SONAM SINHA, Neeta Shrivastava. Synergistic anticancer effect of sulforaphane and cisplatin on sirtuins-mediated epithelial-to-mesenchymal signaling in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4190.

EPHB6 augments both development and drug sensitivity of triple-negative breast cancer tumours

Triple-negative breast cancer (TNBC) tumours that lack expression of oestrogen, and progesterone receptors, and do not overexpress the HER2 receptor represent the most aggressive breast cancer subtype, which is characterised by the resistance to therapy in frequently relapsing tumours and a high rate of patient mortality. This is likely due to the resistance of slowly proliferating tumour-initiating cells (TICs), and understanding molecular mechanisms that control TICs behaviour is crucial for the development of effective therapeutic approaches. Here, we present our novel findings, indicating that an intrinsically catalytically inactive member of the Eph group of receptor tyrosine kinases, EPHB6, partially suppresses the epithelial–mesenchymal transition in TNBC cells, while also promoting expansion of TICs. Our work reveals that EPHB6 interacts with the GRB2 adapter protein and that its effect on enhancing cell proliferation is mediated by the activation of the RAS-ERK pathway, which allows it to elevate the expression of the TIC-related transcription factor, OCT4. Consistent with this, suppression of either ERK or OCT4 activities blocks EPHB6-induced pro-proliferative responses. In line with its ability to trigger propagation of TICs, EPHB6 accelerates tumour growth, potentiates tumour initiation and increases TIC populations in xenograft models of TNBC. Remarkably, EPHB6 also suppresses tumour drug resistance to DNA-damaging therapy, probably by forcing TICs into a more proliferative, drug-sensitive state. In agreement, patients with higher EPHB6 expression in their tumours have a better chance for recurrence-free survival. These observations describe an entirely new mechanism that governs TNBC and suggest that it may be beneficial to enhance EPHB6 action concurrent with applying a conventional DNA-damaging treatment, as it would decrease drug resistance and improve tumour elimination.