Role and Involvement of TENM4 and miR-708 in Breast Cancer Development and Therapy

Abstract

Teneurin 4 (TENM4) is a transmembrane protein that is codified by the ODZ4 gene and is involved in nervous system development, neurite outgrowth, and neuronal differentiation. In line with its involvement in the nervous system, TENM4 has also been implicated in several mental disorders such as bipolar disorder, schizophrenia, and autism. TENM4 mutations and rearrangements have recently been identified in a number of tumors. This, combined with impaired expression in tumors, suggests that it may potentially be involved in tumorigenesis. Most of the TENM4 mutations that are observed in tumors occur in breast cancer, in which TENM4 plays a role in cells' migration and stemness. However, the functional role that TENM4 plays in breast cancer still needs to be better evaluated, and further studies are required to better understand the involvement of TENM4 in breast cancer progression. Herein, we review the currently available data for TENM4's role in breast cancer and propose its use as both a novel target with which to ameliorate patient prognosis and as a potential biomarker. Moreover, we also report data on the tumorigenic role of miR-708 deregulation and the possible use of this miRNA as a novel therapeutic molecule, as miR-708 is spliced out from TENM4 mRNA.

Keywords: Teneurin 4 (TENM4); biomarker; breast cancer; metastasis; miR-708; target; tumor progression.

Figure 1

Schematic representation of the ODZ4 gene and of the TENM4 protein structure: (A) The ODZ4 gene counts 34 exons (NCBI Gene ID: 26011, updated on 23 November 2021). Two microRNA miR-5579 and miR-708 are situated in the first intron of the ODZ4 gene and spliced out. (B) TENM4 protein structure comprehend different domains: an intracellular domain with a nuclear localization sequence and an SH3 binding domain, a transmembrane domain, and an extracellular domain composed by eight EGF repeats, an NHL, and YD domains. “Created with BioRender.com, accessed on 26 November 2021”.

Figure 2

Analysis of ODZ4 genomic alterations in breast cancer patients: (A) ODZ4 alteration frequency observed by analyzing two breast cancer data sets: TCGA (Dataset A) and Metabric (Dataset B). The analyses were performed using the cBioPortal tool (www.cbioportal.org, accessed on 30 November 2021), an open-access, open-source resource for interactive exploration of multidimensional cancer genomics data sets. (B) Overall survival (upper panel) and relapse free status (lower panel) of breast cancer patients that displayed unaltered ODZ4 (blue line) and genomic ODZ4 alterations (red line). Statistical analysis was performed using the Log Rank Test.

Figure 3

TENM4 mRNA expression relevance in breast cancer patients. Correlation between Relapse Free Survival (RFS) and Overall Survival (OS) in Triple Negative Breast Cancer (TNBC) (A,E), HER2-positive (B,F), Progesterone Receptor (PR)-positive (C,G), Estrogen Receptor (ER)-positive (D,H), and Grade 3 (I,J) with high (red) or low (black) TENM4 mRNA expression in the tumor.

Figure 4

Mir-708 relevance in TNBC patients. Correlation between Overall Survival (OS) in TNBC and high (red) or low (black) miR-708 expression in the tumor.

Figure 5

TENM4 expression in HER2-positive breast cancer cells and tumors: (A) Immunoblot of TENM4 and loading control protein (Actin) that compares HER2-positive TUBO epithelial cells (ep), first-passage tumorspheres (P1) and second-passage tumorspheres (P2). (B) Immunoblot of TENM4 and loading control protein (Vinculin) that compares HER2-positive mammary tumors from 9- (NeuT9wA and B), 14- (NeuT14wA and B), and 24- (NeuT24wA and B) week-old BALB-neuT mice. A total of 80 µg of TUBO cells and BALB-neuT tumor lysates were separated via electrophoresis in a 7.5% Mini-Protean TGX precast gel (Bio-Rad) and transferred onto an Immobilon-P PVDF membrane. Following blocking with 5% non-fat dry milk, the membrane was incubated with sheep anti-TENM4 (1 µg/mL, Cat#AF6320, R&D Systems, Minneapolis, MN, USA), with mouse anti-β-Actin (1:200, Clone AC-15, Santa Cruz Biotechnology), and with mouse anti-Vinculin (1:8000, produced in-house).