Premium
ALDH1A1 in patient‐derived bladder cancer spheroids activates retinoic acid signaling leading to TUBB3 overexpression and tumor progression
Author(s) -
Namekawa Takeshi,
Ikeda Kazuhiro,
HorieInoue Kuniko,
Suzuki Takashi,
Okamoto Koji,
Ichikawa Tomohiko,
Yano Akihiro,
Kawakami Satoru,
Inoue Satoshi
Publication year - 2019
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.32505
Subject(s) - cancer research , bladder cancer , cancer , gene knockdown , cancer stem cell , cancer cell , retinoic acid , aldehyde dehydrogenase , small hairpin rna , stem cell , biology , medicine , cell culture , microbiology and biotechnology , enzyme , biochemistry , genetics
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.