Correlation Between Raf/MEK/ERK Signaling Pathway and Clinicopathological Features and Prognosis for Patients With Breast Cancer Having Axillary Lymph Node Metastasis

The clinical significance of cyclin B1 (CCNB1) in invasive breast cancer with emphasis on its contribution to lymphovascular invasion development

BACKGROUND

Lymphovascular invasion (LVI) is regulated through complex molecular mechanisms. Cyclin B1 (CCNB1) was previously determined as being associated with LVI using large cohorts of breast cancer (BC) and artificial neural network (ANN) technique. In this study, we aimed to assess the association between CCNB1 and LVI, other clinicopathological and other LVI-related biomarkers at the molecular (RNA transcriptomic) and proteomic levels in BC.

METHODS

Two transcriptomic BC cohorts (n = 2834) were used to assess the association between the expression of CCNB1 at the mRNA level and clinicopathological characteristics and patient outcome. Tissue microarrays (TMAs) from a well-characterised BC cohort (n = 2480) with long-term outcome were also used to assess the clinical significance of CCNB1 protein expression using immunohistochemistry.

RESULTS

High CCNB1 mRNA expression was associated with aggressive tumour behaviour, including LVI, larger size, higher tumour grade, high lymph nodal stage, hormonal receptor negativity, HER2 positivity and poor clinical outcome (all p < 0.0001). Similarly, high CCNB1 protein expression was associated with higher tumour grade, hormonal receptor negativity and HER2 positivity (all p < 0.0001). Additionally, there was a significant association between CCNB1- and LVI-related biomarkers including N-cadherin, P-cadherin and TWIST2 at the transcriptomic and proteomic level. Multivariate analysis revealed that CCNB1 was an independent predictor of shorter BC-specific survival (HR = 1.3; 95% CI 1.2-1.5; p = 0.010).

CONCLUSION

CCNB1 is a key gene associated with LVI in BC and has prognostic value. More functional studies are warranted to unravel the mechanistic role of CCNB1 in the development of LVI.

ERK activation modulates invasiveness and Reactive Oxygen Species (ROS) production in triple negative breast cancer cell lines

Triple negative breast cancer (TNBC) is the breast cancer subtype with the worst prognosis and still lacks a targeted therapy. In this study, we found increased ERK phosphorylation in TNBC cell lines and an important role for ERK in sustaining the migration of TNBC cells. Although ROS have been suggested to have an important role in sustaining MAPK signaling, antioxidant treatment increased ERK phosphorylation, probably suggesting increased invasive potential. Interestingly, treatment with PD0325901 (PD), a MEK inhibitor, decreased ROS levels in TNBC cells and decreased mitochondrial fragmentation in the MDAMB231 cell line. Our data supports an important role for MEK/ERK in TNBC, sustaining cellular migration, regulating mitochondrial dynamics and ROS production in this breast cancer subtype.

Sulforaphane suppresses metastasis of triple-negative breast cancer cells by targeting the RAF/MEK/ERK pathway

Breast cancer metastasis is the main cause of cancer death in women, so far, no effective treatment has inhibited breast cancer metastasis. Sulforaphane (SFN), a natural compound derived from broccoli, has shown potential health benefits in many cancers. However, research on breast cancer metastasis is still insufficient. Here, we showed that SFN, including its two isomers of R-SFN and S-SFN, significantly inhibited TGF-β1-induced migration and invasion in breast cancer cells. Proteomic and phosphoproteomic analysis showed that SFN affected the formation of the cytoskeleton. Subsequent experiments confirmed that SFN significantly inhibited TGF-β1-induced actin stress fiber formation and the expression of actin stress fiber formation-associated proteins, including paxillin, IQGAP1, FAK, PAK2, and ROCK. Additionally, SFN is directly bound to RAF family proteins (including ARAF, BRAF, and CRAF) and inhibited MEK and ERK phosphorylation. These in vitro results indicate that SFN targets the RAF/MEK/ERK signaling pathway to inhibit the formation of actin stress fibers, thereby inhibiting breast cancer cell metastasis.

Cross-talk between myeloid-derived suppressor cells and Mucin1 in breast cancer vaccination: On the verge of a breakthrough

Although breast cancer is one of the leading troublesome cancers, the available therapeutic options have not fulfilled the desired outcomes. Immune-based therapy has gained special attention for breast cancer treatment. Although this approach is highly tolerable, its low response rate has rendered it as an undesirable approach. This review aims to describe the essential oncogenic pathways involved in breast cancer, elucidate the immunosuppression and oncogenic effect of Mucin1, and introduce myeloid-derived suppressor cells, which are the main culprits of anti-tumoral immune response attenuation. The various auto-inductive loops between Mucin1 and myeloid-derived suppressor cells are focal in the suppression of anti-tumoral immune responses in patients with breast cancer. These cross-talks between the Mucin1 and myeloid-derived suppressor cells can be the underlying causes of immunotherapy's impotence for patients with breast cancer. This approach can pave the road for the development of a potent vaccine for patients with breast cancer and is translated into clinical settings.

Prognostic significance of branched-chain amino acid transferase 1 and CD133 in triple-negative breast cancer

BACKGROUND

Previous studies have shown that branched-chain amino acid transferase 1 (BCAT1) is associated with tumour progression in triple-negative breast cancer (TNBC). Furthermore, CD133 has emerged as a novel cancer stem cell marker for indicating tumour progression. However, the prognostic significance of these two markers remains to be verified. This study was conducted to investigate the correlation between BCAT1 and CD133 expression and clinicopathological features, as well as the prognosis of patients with TNBC.

METHODS

The study cohort included 291 patients with TNBC. Tissue microarrays were constructed for both cancer and normal tissues. The expression of BCAT1 and CD133 was detected by immunohistochemical staining, and the levels were evaluated using an H-scoring system. Cut-off points for BCAT1 and CD133 expression were determined using receiver operating characteristic curves.

RESULTS

The median follow-up time for the study participants was 68.73 months (range: 1.37-103.6 months). The 5-year disease-free survival (DFS) and overall survival (OS) rates of the 291 patients with TNBC were 72.51 and 82.47%, respectively. Higher levels of BCAT1 and CD133 expression independently indicated shorter DFS and OS. High levels of both BCAT1 and CD133 expression were detected in 36 (12.37%) patients, who had significantly shorter DFS and OS (both P < 0.001) compared to other patients.

CONCLUSION

BCAT1 and CD133 can be considered as biomarkers with prognostic significance for TNBC.

Oxymatrine Inhibits Proliferation and Migration of Vulvar Squamous Cell Carcinoma Cells via Attenuation of the RAS/RAF/MEK/ERK Pathway

Purpose

To evaluate the anti-tumor effects of oxymatrine in vulvar squamous cell carcinoma (VSCC) cells and to explore the underlying mechanisms.

Methods

We selected SW962 and A431 VSCC cell lines. Cell proliferation was examined using MTT assay. Cell cycle and apoptosis were detected using flow cytometry. Migration and invasion were evaluated using transwell and wound-healing assays. The relevant protein expression and signaling pathways were analyzed using Western blotting.

Results

Oxymatrine inhibited the proliferation of SW962 and A431 VSCC cells in a time- and dose-dependent manner. Oxymatrine induced cell cycle arrest in the G2/M phase by increasing the protein expression of P21 and decreasing levels of cyclin B1 and CDC2. Oxymatrine upregulated the expression of cleaved-caspase 3 and BAX and downregulated the expression of BCL2, which led to an increase in apoptosis. Oxymatrine also suppressed the migration and invasion of SW962 and A431 cells by reducing levels of MMP2 and MMP9. After treatment with oxymatrine or a RAS inhibitor (salirasib), expression levels of RAS, p-RAF, p-MEK, p-ERK, C-MYC, and MMP2 were reduced. When TGF-β1 was used to stimulate SW962 and A431 cells, the expression of the above proteins increased; this increase was reversed by using oxymatrine or salirasib again.

Conclusion

Oxymatrine inhibits proliferation and migration of VSCC cells by blocking the RAS/RAF/MEK/ERK pathway.

[Mig-7 gene silencing inhibits vasculogenic mimicry formation and invasion of glioma U251 cells in vitro by suppressing MEK/ERK signaling]

OBJECTIVE

To investigate the inhibitory effects of silencing migration-inducing gene-7 (Mig-7) on vasculogenic mimicry formation, migration and invasion of human glioma cells in vitro and whether MEK/ERK signaling pathway mediates these effects.

METHODS

Human glioma U251 cells were infected by lentiviral vectors carrying a small interfering RNA targeting Mig-7 gene (sh-Mig-7) or a negative control shRNA (sh-NC), and real-time quantitative PCR was used to detect the expression level of Mig-7 mRNA in the cells. Three-dimensional culture and Transwell chamber invasion assay were used to observe the effect of Mig-7 gene silencing on vasculogenic mimicry formation and invasion ability of the U251 cells. Western blotting was performed to detect the changes in the protein expression levels of MEK/ERK in the infected cells.

RESULTS

We successfully obtained a U251 cell line with stable low expression of Mig-7 gene using RNA interference technique. Compared with the cells infected with sh-NC lentivirus and the non- infected cells, U251 cells infected with the lentiviral vector carrying sh-Mig-7 showed significantly decreased expression level of Mig-7 (P &lt; 0.01) with obviously lowered vasculogenic mimicry formation and invasion abilities (P &lt; 0.05). Mig-7 silencing also significantly lowered the expressions of MEK and ERK proteins in U251 cells (P &lt; 0.05).

CONCLUSIONS

Silencing of Mig-7 gene inhibits vasculogenic mimicry formation and invasion of U251 cells possibly by suppressing MEK/ERK signaling, suggesting the important role of Mig-7 gene in vasculogenic mimicry formation and invasion of human glioma cells.

Anti-tumor and anti-metastasis efficacy of E6201, a MEK1 inhibitor, in preclinical models of triple-negative breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) lacks the receptor targets estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2, and thus, it does not respond to receptor-targeted treatments. TNBC has higher recurrence, metastasis, and mortality rates than other subtypes of breast cancer. Mounting data suggest that the MAPK (also known as RAS-RAF-MEK-ERK) pathway is an important therapeutic target in TNBC.

METHODS

To evaluate anti-tumor and anti-metastasis efficacy of E6201, we used cell proliferation assay, soft agar assay, cell cycle assay, Annexin V staining assay, immunoblotting analysis, immunohistochemistry, migration assay, invasion assay, mammary fat pad xenograft, and experimental and spontaneous metastasis xenograft models. We also evaluated the anti-tumor efficacy of E6201 plus CDK4/6 inhibitor, mTOR inhibitor, or ATR inhibitor.

RESULTS

E6201 inhibited TNBC cell colony formation, migration, and invasion in a dose-dependent manner. E6201 induced G1 cell cycle arrest and apoptosis. E6201 inhibited TNBC xenograft growth and inhibited TNBC lung metastasis and improved mouse survival in experimental metastasis and spontaneous metastasis assays. Immunohistochemical staining demonstrated that E6201 decreased the metastatic burden in the lung and decreased phosphorylated ERK expression in a dose-dependent manner. Combination of E6201 with CDK4/6 inhibitor or mTOR inhibitor enhanced E6201's in vitro anti-tumor efficacy.

CONCLUSION

These results indicate that E6201 exhibits anti-tumor efficacy against TNBC in vitro and anti-metastasis efficacy against TNBC in vivo. These results provide a rationale for further clinical development of E6201 as a MAPK-pathway-targeted therapy for TNBC.