Abigail Bagdasaryants

Introduction. Breast cancer is the leading cause of cancer mortality in women worldwide. Triple negative breast cancer (TNBC) is an aggressive subtype with higher rates of metastasis, higher probability of relapse, and poorer patient outcomes.¹ TNBC presents more commonly in younger, Black, and Hispanic patients, and is characterized for its lack of estrogen, progesterone, and human epidermal growth factor receptor 2 receptors.^{1, 2} Previous studies have shown that TGF-β and NF-κB signaling pathways mediate epithelial-mesenchymal transition (EMT) and promote metastasis in TNBC.^{3, 4, 5} NF-κB is overexpressed in breast cancer, and high levels are correlated with high levels of mesenchymal biomarkers.⁵ Dysregulation of long non-coding RNAs (lncRNAs) has been implicated in breast cancer; NF-κB Interacting LncRNA (NΚILA) is a modulator of NF-κB, while TGF‐β is an NF-κB activator.^{4, 6, 7} This poses the question of how NΚILA is involved in TGF‐β-NF-κB induced EMT, and whether it has therapeutic implications. Methods. Western blot and nuclear immunofluorescence staining assessed NF-κB regulators including IKK and IκB in TGF-β treated MCF-7 cells with upregulated or silenced NΚILA.⁴ MCF-7 and BT474 cells were treated with TGF-β and lentiviral vectors to knockdown or overexpress NΚILA, and injected into NOD-SCID mice.⁴ Tumor xenografts and effects on survival were assessed with H&E, immunohistochemistry, qRT-PCR, and Kaplan-Meier survival curves. qRT-PCR measured E-cadherin and NΚILA expression from 164 patient samples.⁴ Results. NF-κB inhibition reduces TGF-β induced EMT and metastasis. NΚILA expression is upregulated by TGF-β treatment and downregulated by NF-κB inhibitors JSH-23 and Bay.⁴ MCF-7 TGF-β treated cells with siRNA knocked-down NΚILA exhibited more mesenchymal phenotypes and increased invasive potential.⁴ NΚILA upregulation blocks NF-κB activation by inhibiting IκB phosphorylation and nuclear translocation, and thereby reduces TGF-β induced metastasis.^{4, 6} Mice treated with TGF-β and silenced NΚILA suffered lung and kidney metastases and showed worse survival.⁴ NΚILA expression is inversely related to EMT phenotypes in clinical breast cancer samples, and patients’ whose samples had higher NΚILA levels experienced longer survival.⁴ Conclusions. Low levels of NΚILA in highly metastatic breast cancer cell lines and patients with worse outcomes shows the potential of NΚILA as a prognostic biomarker for TNBC.⁴ Wu et al. demonstrated treatment with ectopically expressed NΚILA improved survival of mice with metastases induced by TGF-β and knocked-down NΚILA, providing proof-of-concept for use of NΚILA in improving survival of TNBC patients with high levels of metastasis.^{4, 6} Future research should explore options for gene therapy and delivery systems for NΚILA.

1. Zhang W, Guan X, Tang J. The long non-coding RNA landscape in triple-negative breast cancer. Cell Prolif. 2021 Feb;54(2):e12966. doi: 10.1111/cpr.12966. Epub 2020 Dec 13. PMID: 33314471; PMCID: PMC7848969.
2. Sharma P. Biology and Management of Patients With Triple-Negative Breast Cancer. Oncologist. 2016 Sep;21(9):1050-62. doi: 10.1634/theoncologist.2016-0067. Epub 2016 Jul 11. PMID: 27401886; PMCID: PMC5016071.
3. Tian J, Al-Odaini AA, Wang Y, Korah J, Dai M, Xiao L, Ali S, Lebrun JJ. KiSS1 gene as a novel mediator of TGFβ-mediated cell invasion in triple negative breast cancer. Cell Signal. 2018 Jan;42:1-10. doi: 10.1016/j.cellsig.2017.10.002. Epub 2017 Oct 6. PMID: 28988968.
4. Wu W, Chen F, Cui X, Yang L, Chen J, Zhao J, Huang D, Liu J, Yang L, Zeng J, Zeng Z, Pan Y, Su F, Cai J, Ying Z, Zhao Q, Song E, Su S. LncRNA NKILA suppresses TGF-β-induced epithelial-mesenchymal transition by blocking NF-κB signaling in breast cancer. Int J Cancer. 2018 Nov 1;143(9):2213-2224. doi: 10.1002/ijc.31605. Epub 2018 Aug 7. PMID: 29761481.
5. Pires BR, Mencalha AL, Ferreira GM, de Souza WF, Morgado-Díaz JA, Maia AM, Corrêa S, Abdelhay ES. NF-kappaB Is Involved in the Regulation of EMT Genes in Breast Cancer Cells. PLoS One. 2017 Jan 20;12(1):e0169622. doi: 10.1371/journal.pone.0169622. PMID: 28107418; PMCID: PMC5249109.
6. Liu B, Sun L, Liu Q, Gong C, Yao Y, Lv X, Lin L, Yao H, Su F, Li D, Zeng M, Song E. A cytoplasmic NF-κB interacting long noncoding RNA blocks IκB phosphorylation and suppresses breast cancer metastasis. Cancer Cell. 2015 Mar 9;27(3):370-81. doi: 10.1016/j.ccell.2015.02.004. PMID: 25759022.
7. Zhang Y, Wu J, Jing H, Huang G, Sun Z, Xu S. Long noncoding RNA MEG3 inhibits breast cancer growth via upregulating endoplasmic reticulum stress and activating NF-κB and p53. J Cell Biochem. 2019 Apr;120(4):6789-6797. doi: 10.1002/jcb.27982. Epub 2018 Dec 16. PMID: 30556250.