Targeting collagen XVIII improves the efficiency of ErbB inhibitors in breast cancer models
Raman Devarajan, … , Taina Pihlajaniemi, Ritva Heljasvaara
Raman Devarajan, … , Taina Pihlajaniemi, Ritva Heljasvaara
Published July 27, 2023
Citation Information: J Clin Invest. 2023;133(18):e159181. https://doi.org/10.1172/JCI159181.
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Research Article Oncology

Targeting collagen XVIII improves the efficiency of ErbB inhibitors in breast cancer models

Abstract

The tumor extracellular matrix (ECM) critically regulates cancer progression and treatment response. Expression of the basement membrane component collagen XVIII (ColXVIII) is induced in solid tumors, but its involvement in tumorigenesis has remained elusive. We show here that ColXVIII was markedly upregulated in human breast cancer (BC) and was closely associated with a poor prognosis in high-grade BCs. We discovered a role for ColXVIII as a modulator of epidermal growth factor receptor tyrosine kinase (ErbB) signaling and show that it forms a complex with ErbB1 and -2 (also known as EGFR and human epidermal growth factor receptor 2 [HER2]) and α6-integrin to promote cancer cell proliferation in a pathway involving its N-terminal portion and the MAPK/ERK1/2 and PI3K/AKT cascades. Studies using Col18a1 mouse models crossed with the mouse mammary tumor virus–polyoma virus middle T antigen (MMTV-PyMT) mammary carcinogenesis model showed that ColXVIII promoted BC growth and metastasis in a tumor cell–autonomous manner. Moreover, the number of mammary cancer stem cells was significantly reduced in the MMTV-PyMT and human cell models upon ColXVIII inhibition. Finally, ablation of ColXVIII substantially improved the efficacy of ErbB-targeting therapies in both preclinical models. In summary, ColXVIII was found to sustain the stemness properties of BC cells and tumor progression and metastasis through ErbB signaling, suggesting that targeting ColXVIII in the tumor milieu may have important therapeutic potential.

Authors

Raman Devarajan, Valerio Izzi, Hellevi Peltoketo, Gunilla Rask, Saila Kauppila, Marja-Riitta Väisänen, Heli Ruotsalainen, Guillermo Martínez-Nieto, Sanna-Maria Karppinen, Timo Väisänen, Inderjeet Kaur, Jussi Koivunen, Takako Sasaki, Robert Winqvist, Aki Manninen, Fredrik Wärnberg, Malin Sund, Taina Pihlajaniemi, Ritva Heljasvaara

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Figure 3

ColXVIII promotes BC cell proliferation through its N-terminal domain.

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ColXVIII promotes BC cell proliferation through its N-terminal domain. (...
(A and B) Representative immunoblots of ColXVIII in human BC and mammary epithelial cell lines. (A) In cell lysates, the size of the major ColXVIII band of approximately 180 kDa corresponds to the core polypeptide of the short isoform (60). (B) JIMT-1 and MDA-MB-231 cells secreted high amounts of glycosylated ColXVIII, which appears as a broad smear over 250 kDa. In A and B, biological replicates: lysates, n ≥5; culture media, n = 3. (C) Relative expression of the short, medium, and long COL18A1 mRNA transcripts normalized to GAPDH in human BC cell lines (n = 3). The primer pairs are listed in Supplemental Table 5. (D) qRT-PCR analysis of total COL18A1 mRNA after its KD in BC cell lines (n = 6). (E and F) Examples of immunoblots of ColXVIII protein levels in various KD cell lines and corresponding scrambled controls (S). n ≥3 biological replicates for each cell line. In A, E, and F, the loading control was β-tubulin. (G) Confluence of ColXVIII-KD versus scrambled cell lines (percentage), measured by an IncuCyte live-cell analysis system for 96 hours (n = 9). (H–J) Confluence of KD cell lines after administration of recombinant NC ColXVIII fragments (500 ng/mL) to the KD cells (n = 3). Untreated scrambled cell lines are shown as controls. TSP-1, TSP-1 domain; NC11, full-length N-terminal NC. Data in C, D, G, and H–J are presented as the mean ± SD. **P < 0.01, ***P < 0.001, and ****P < 0.0001, by 2-tailed Student’s t test (C, D, and G) and 2-way ANOVA with Dunnett’s multiple-comparison (treated vs. ColXVIII-KD) (H–J).