The protein secretion modulator TMED9 drives CNIH4/TGFα/GLI signaling opposing TMED3-WNT-TCF to promote colon cancer metastases

Abstract

How cells in primary tumors initially become pro-metastatic is not understood. A previous genome-wide RNAi screen uncovered colon cancer metastatic suppressor and WNT promoting functions of TMED3, a member of the p24 ER-to-Golgi protein secretion family. Repression of canonical WNT signaling upon knockdown (kd) of TMED3 might thus be sufficient to drive metastases. However, searching for transcriptional influences on other family members here we find that TMED3 kd leads to enhanced TMED9, that TMED9 acts downstream of TMED3 and that TMED9 kd compromises metastasis. Importantly, TMED9 pro-metastatic function is linked to but distinct from the repression of TMED3-WNT-TCF signaling. Functional rescue of the migratory deficiency of TMED9 kd cells identifies TGFα as a mediator of TMED9 pro-metastatic activity. Moreover, TMED9 kd compromises the biogenesis, and thus function, of TGFα. Analyses in three colon cancer cell types highlight a TMED9-dependent gene set that includes CNIH4, a member of the CORNICHON family of TGFα exporters. Our data indicate that TGFA and CNIH4, which display predictive value for disease-free survival, promote colon cancer cell metastatic behavior, and suggest that TMED9 pro-metastatic function involves the modulation of the secretion of TGFα ligand. Finally, TMED9/TMED3 antagonism impacts WNT-TCF and GLI signaling, where TMED9 primacy over TMED3 leads to the establishment of a positive feedback loop together with CNIH4, TGFα, and GLI1 that enhances metastases. We propose that primary colon cancer cells can transition between two states characterized by secretion-transcription regulatory loops gated by TMED3 and TMED9 that modulate their metastatic proclivities.

Functional Pro-metastatic Heterogeneity Revealed by Spiked-scRNAseq Is Shaped by Cancer Cell Interactions and Restricted by VSIG1

“…In this context, metastatic states could depend on epigenetic events and/or cell-to-cell signaling. Support for this idea includes the balance of anti-and pro-metastatic states via the modulation of protein secretion (Duquet et al, 2014;Mishra et al, 2019) and the existence of positive interactions that affect metastatic growth, multiclonal invasion, and clinical behavior in various cancers (Miller, 1983;Inda et al, 2010;Calbo et al, 2011;Celià -Terrassa et al, 2012;Cleary et al, 2014;Marusyk et al, 2014;Vinci et al, 2018). However, since colon cancer heterogeneity is reestablished in single-cell clonal grafts (Dalerba et al, 2011), and dominant positive interactions would tend to homogenize the outcome, these may be secondary to the initial establishment of pro-metastatic states.…”

Transmembrane emp24 domain proteins in development and disease.

“…TMED3-mediated WNT signalling is proposed to inhibit metastasis by repressing TMED9. In the same study, loss of TMED3 resulted in increased TMED9 levels and was correlated with increased TGF-β signalling and upregulation of genes with migratory and invasive roles, while also repressing WNT signalling (Mishra et al, 2019). Thus, similarly to TMED2, the malignant properties of TMED3 are cell typespecific.…”

A Novel Five-gene Signature Predicts Overall Survival in Hepatocellular Carcinoma

“…In summary, aberrant expression of the five genes was validated in HCC. activity [22]. The role of CNIH4 in HCC has not been reported yet.…”