ALDH1A1 in patient‐derived bladder cancer spheroids activates retinoic acid signaling leading to TUBB3 overexpression and tumor progression

Abstract

Acquired chemoresistance is a critical issue for advanced bladder cancer patients during long‐term treatment. Recent studies reveal that a fraction of tumor cells with enhanced tumor‐initiating potential, or cancer stem‐like cells (CSCs), may particularly contribute to acquired chemoresistance and recurrence. Thus, CSC characterization will be the first step towards understanding the mechanisms underlying advanced disease. Here we generated long‐term patient‐derived cancer cells (PDCs) from bladder cancer patient specimens in spheroid culture, which is favorable for CSC enrichment. Pathological features of bladder cancer PDCs and PDC‐dependent patient‐derived xenografts (PDXs) were basically similar to those of their corresponding patients’ specimens. Notably, CSC marker aldehyde dehydrogenase 1A1 (ALDH1A1), a critical enzyme that synthesizes retinoic acid (RA), was abundantly expressed in PDCs. ALDH1A1 inhibitors and shRNAs repressed both PDC proliferation and spheroid formation, whereas all‐trans RA could rescue ALDH1A1 shRNA‐suppressed spheroid formation. ALDH inhibitor also reduced the in vivo growth of PDC‐derived xenografts. ALDH1A1 knockdown study showed that tubulin beta III (TUBB3) was one of the downregulated genes in PDCs. We identified functional RA response elements in TUBB3 promoter, whose transcriptional activities were substantially activated by RA. Clinical survival database reveals that TUBB3 expression may associate with poor prognosis in bladder cancer patients. Moreover, TUBB3 knockdown was sufficient to suppress PDC proliferation and spheroid formation. Taken together, our results indicate that ALDH1A1 and its putative downstream target TUBB3 are overexpressed in bladder cancer, and those molecules could be applied to alternative diagnostic and therapeutic options for advanced disease.

Emerging Roles of Cancer Stem Cells in Bladder Cancer Progression, Tumorigenesis, and Resistance to Chemotherapy: A Potential Therapeutic Target for Bladder Cancer

“…The ALDH1A1-positive cell population is enriched in BC and its upregulation is associated with progression, aggressiveness, recurrence, shorter survival time, and a poor prognosis of BC [39,40]. Moreover, knockdown of the ALDH1A1 gene by the specific siRNA significantly decreased its clonogenicity and tumorigenic potential in bladder CSCs [39,41]. It is one of the top upregulated genes of BC organoids compared with normal bladder tissues [27].…”

“…Su et al found that ALDH1A1 + BC cells have higher clonogenicity and tumorigenicity than ALDH1A1 ones [39]. Recently, ALDH1A1 in patient-derived BC spheroids was shown to stimulate retinoic acid signaling, which leads to the overexpression of tubulin b III (TUBB3) and BC progression [41].…”

Organotypic Modeling of the Tumor Landscape

“…However, these approaches fail to account for critical aspects of the TME. Indeed, (Yin et al, 2016) Bladder cancer (Namekawa et al, 2020) CAF-mediated interactions Lung cancer (Chen et al, 2018) Pancreatic cancer (Ware et al, 2016) Invasion Breast cancer (Avgustinova et al, 2016) Colon cancer (Nam et al, 2018) Colorectal cancer (Libanje et al, 2019) Vessel sprouting and intravasation Colon cancer (Ehsan et al, 2014) Niche activation and colonization Breast cancer (del Pozo Martin et al, 2015) High-throughput toxicology assay Breast cancer (Lee et al, 2008)…”

Patient-Derived Urothelial Cancer Xenograft Models: A Systematic Review and Future Perspectives

“…Using multiple clinical specimens, we successfully identified cases in which a combination of disulfiram, an FDA approved drug for alcoholism, and cisplatin was predicted to produce synergy [41]. In another example of the potential superiority of 3D culture, Namekawa et al showed that ALDH1A1 expression was increased in T24 cells cultured in 3D compared to 2D cultures and that ALDH1A1 inhibition in patient-derived spheroids and mouse models suppressed the tumor growth [42].…”