Abstract B007: LIN28B promotes collective cell invasion and colorectal cancer metastasis via a novel CLDN1 and NOTCH3 axis

Abstract

Abstract Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second most common cause of cancer death worldwide. The 5-year survival rate is 90% in patients with localized tumors, but the survival rate drastically decreases to 14% in patients with distant metastasis. Therefore, it is imperative to elucidate the molecular mechanisms underlying CRC metastasis. The RNA-binding protein LIN28B is overexpressed in over 30% of patients with CRC and is associated with poor prognosis. Indeed, our previous work revealed that LIN28B promotes liver metastasis in a subcutaneous xenograft model of CRC as well as a portal vein injection model. In the present study, we investigated the mechanism by which LIN28B promotes colorectal tumor progression and metastasis. To assess biological changes induced by LIN28B, we established CRC cells (DLD-1 and LoVo) with high expression of LIN28B (LIN28Bhigh). LIN28B overexpression upregulated Claudin-1 (CLDN1), a protein that functions as a major constituent of the tight junction complexes. RNA immunoprecipitation revealed that LIN28B directly binds to and stabilizes CLDN1 at a post-transcriptional level. Knockdown of CLDN1 expression in LIN28Bhigh cells suppresses cell aggregation, wound healing rate, and collective invasion. Using a mouse model of metastatic CRC, we reveal that knockdown of CLDN1 inhibits liver metastasis of LIN28Bhigh CRC cells. RNA-sequencing of metastatic liver tumors from LIN28Bhigh cells showed that NOTCH3 works downstream of the LIN28B-CLDN1 axis to induce cell aggregation, collective invasion, and metastatic liver tumor formation. Inhibition of Notch signaling by DAPT, an inhibitor of the γ-secretase complex, significantly reduced metastatic liver tumors in vivo. Taken together, our results indicate that LIN28B promotes cell aggregation, invasion, and liver metastasis in CRC through post-transcriptional induction of CLDN1 and upregulation of NOTCH3. Development of new therapies that target LIN28B-CLDN1-NOTCH3 axis may provide an effective strategy for stage 4 CRC. This work was supported by 9R01CA277795-22. Citation Format: Alice E. Shin, Kensuke Sugiura, Yasunori Masuike, Kensuke Suzuki, Christopher J. Lengner, Anil K. Rustgi. LIN28B promotes collective cell invasion and colorectal cancer metastasis via a novel CLDN1 and NOTCH3 axis [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr B007.