Glucose metabolism in aggressive cancers
Schwab A, Siddiqui A, Vazakidou ME, Napoli F, Böttcher M, Menchicchi B, Raza U, Saatci Ö, Krebs AM, Ferrazzi F, Rapa I, Dettmer-Wilde K, Waldner MJ, Ekici AB, Rasheed SAK, Mougiakakos D, Oefner PJ, Şahin Ö, Volante M, Greten FR, Brabletz T, Ceppi P.
Cancer Research. 2018 Jan 17. pii: canres.2834.2017. doi: 10.1158/0008-5472.CAN-17-2834. PMID: 29343522.
Cancer cells alter their metabolism to support their malignant properties.In this study, we report that the glucose-transforming polyol pathway (PP) gene aldo-keto-reductase-1-member-B1 (AKR1B1) strongly correlates with epithelial-to-mesenchymal transition (EMT). This association was confirmed in samples from lung cancer patients and from an EMT-driven colon cancer mouse model with p53 deletion. In vitro, mesenchymal-like cancer cells showed increased AKR1B1 levels, and AKR1B1 knockdown was sufficient to revert EMT. An equivalent level of EMT suppression was measured by targeting the downstream enzyme sorbitol-dehydrogenase (SORD), further pointing at the involvement of the PP.Comparative RNA sequencing confirmed a profound alteration of EMT in PP-deficient cells, revealing a strong repression of TGF-β signature genes. Excess glucose was found to promote EMT through autocrine TGF-β stimulation, while PP-deficient cells were refractory to glucose-induced EMT.These data show that PP represents a molecular link between glucose metabolism, cancer differentiation, and aggressiveness, and may serve as a novel therapeutic target.
Thymidylate Synthase in EMT and cancer stemness
Siddiqui A, Gollavilli PN, Schwab A, Vazakidou ME, Ersan PG, Ramakrishnan M, Pluim D, Coggins S, Saatci O, Annaratone L, Hm Schellens J, Kim B, Asangani IA, Rasheed SAK, Marchiò C, Sahin O, Ceppi P.
Cell Death and Differentiation. 2019 Feb 8. doi: 10.1038/s41418-019-0289-6.
Cancer cells frequently boost nucleotide metabolism (NM) to support their increased proliferation, but the consequences of elevated NM on tumor de-differentiation are mostly unexplored. Here, we identified a role for thymidylate synthase (TS), a NM enzyme and established drug target, in cancer cell de-differentiation and investigated its clinical significance in breast cancer (BC). In vitro, TS knockdown increased the population of CD24+ differentiated cells, and attenuated migration and sphere-formation. RNA-seq profiling indicated repression of epithelial-to-mesenchymal transition (EMT) signature genes upon TS knockdown, and TS-deficient cells showed an increased ability to invade and metastasize in vivo, consistent with the occurrence of a partial EMT phenotype. Mechanistically, TS enzymatic activity was found essential for maintenance of the EMT/stem-like state by fueling a dihydropyrimidine dehydrogenase-dependent pyrimidine catabolism. In patient tissues, TS levels were found significantly higher in poorly differentiated and in triple negative BC, and strongly correlated with worse prognosis. The present study provides the rationale to study in-depth the role of NM at the crossroads of proliferation and differentiation, and depicts new avenues for the design of novel drug combinations for the treatment of BC.
Siddiqui A, Vazakidou ME, Schwab A, Napoli F, Fernandez-Molina C, Rapa I, Stemmler MP, Volante M, Brabletz T, Ceppi P.
Journal of Pathology. 2017 Jun;242(2):221-233. doi: 10.1002/path.4897. PMID: 28337746.
Thymidylate synthase (TS) is a fundamental enzyme in the nucleotide metabolism and one of the oldest anti-cancer targets. We discovered a significant correlation between TS and the markers of EMT, a developmental process that allows the cancer cells to acquire features of aggressiveness, like motility and chemoresistance. TS levels were found significantly augmented in mesenchymal-like compared to epithelial-like cancer cells, and up-regulated following EMT induction by TGF-Beta. Moreover, mesenchymal-like cells were found more resistant to TS-inhibiting drugs. Importantly, a particularly relevant association was found between TS and the powerful EMT driver ZEB1, which was confirmed in clinical specimens from lung tumors and in a genetic mouse model of pancreatic cancer with ZEB1 deletion. A bioinformatic analysis revealed that TS expression was negatively correlated with that of several EMT-suppressing microRNAs (miRNA)s. By luciferase assays we could confirm the role of EMT-suppressing miRNAs in regulating TS, and we identified a novel specific role for miR-375 in targeting TS 3’UTR. Functionally, we found that ZEB1 could indirectly increase TS levels through the regulation of miR-375. Interestingly, TS itself showed to have a regulatory role on EMT in cancer cells. Conversely, TS overexpression could promote EMT and stem-like markers. All together, these data indicate the existence of an unprecedented functional loop involving the TS enzyme, ZEB1 and EMT-related miRNAs that govern cancer differentiation.