Gene expression profiles of prostate cancer stem cells isolated by aldehyde dehydrogenase activity assay.

Prostate cancer cells include a small population of cancer stem-like/cancer initiating cells, which have roles in cancer initiation and progression. Recently aldehyde dehydrogenase activity was used to isolate stem cells of various cancer and normal cells. We evaluated the aldehyde dehydrogenase activity of the human prostate cancer cell line 22Rv1 (ATCC®) with the ALDEFLUOR® assay and determined its potency as prostate cancer stem-like/cancer initiating cells. The human prostate cancer cell line 22Rv1 was labeled with ALDEFLUOR reagent and analyzed by flow cytometry. ALDH1(high) and ALDH1(low) cells were isolated and tumorigenicity was evaluated by xenograft transplantation into NOD/SCID mice. Tumor sphere forming ability was evaluated by culturing in a floating condition. Invasion capability was evaluated by the Matrigel™ invasion assay. Gene expression profiling was assessed by microarrays and reverse transcriptase-polymerase chain reaction. ALDH1(high) cells were detected in 6.8% of 22Rv1 cells, which showed significantly higher tumorigenicity than ALDH1(low) cells in NOD/SCID mice (p < 0.05). Gene expression profiling revealed higher expression of the stem cell related genes PROM1 and NKX3-1 in ALDH1(high) cells than in ALDH1(low) cells. ALDH1(high) cells also showed higher invasive capability and sphere forming capability than ALDH1(low) cells. Results indicate that cancer stem-like/cancer initiating cells are enriched in the ALDH1(high) population of the prostate cancer cell line 22Rv1. This approach may provide a breakthrough to further clarify prostate cancer stem-like/cancer initiating cells. To our knowledge this is the first report of cancer stem-like/cancer initiating cells of 22Rv1 using the aldehyde dehydrogenase activity assay.

Nishida S ，Hirohashi Y ，Torigoe T ，Kitamura H ，Takahashi A ，Masumori N ，Tsukamoto T ，Sato N ... -  《-》

Coordinated expression of REG4 and aldehyde dehydrogenase 1 regulating tumourigenic capacity of diffuse-type gastric carcinoma-initiating cells is inhibited by TGF-β.

Aldehyde dehydrogenase 1 (ALDH1) has been shown to serve as a marker for cancer-initiating cells (CICs), but little is known about the regulation of the CIC functions of ALDH1+ cancer cells. We isolated ALDH1+ cells from human diffuse-type gastric carcinoma cells and characterized these cells using an Aldefluor assay. ALDH1+ cells constituted 5-8% of the human diffuse-type gastric carcinoma cells, OCUM-2MLN and HSC-39; were more tumourigenic than ALDH1- cells; and were able to self-renew and generate heterogeneous cell populations. Using gene expression microarray analyses, we identified REG4 (regenerating islet-derived family, member 4) as one of the genes up-regulated in ALDH1+ cells, and thus as a novel marker for ALDH1+ tumour cells. Induced expression of REG4 enhanced the colony-forming ability of OCUM-2MLN cells, while knockdown of REG4 inhibited the tumourigenic potential of ALDH1+ cells. We further found that TGF-β signalling reduces the expression of ALDH1 and REG4, and the size of the ALDH1+ cell population. In human diffuse-type gastric carcinoma tissues, the expression of ALDH1 and REG4 correlated with each other, as assessed by immunohistochemistry, and ALDH1 expression correlated inversely with Smad3 phosphorylation as a measure of TGF-β signalling. These findings illustrate that, in diffuse-type gastric carcinoma, REG4 is up-regulated in ALDH1+ CICs, and that the increased tumourigenic ability of ALDH1+ cells depends on REG4. Moreover, TGF-β down-regulates ALDH1 and REG4 expression, which correlates with a reduction in CIC population size and tumourigenicity. Targeting REG4 in ALDH1+ CICs may provide a novel strategy in the treatment of diffuse-type gastric carcinoma.

Katsuno Y ，Ehata S ，Yashiro M ，Yanagihara K ，Hirakawa K ，Miyazono K ... -  《-》

[Aldehyde dehydrogenase 1 can be used as a new marker of cancer stem cells in laryngeal cancer cells in vitro].

Jin X ，Zhao Y ，Qian J ，Tang J ，Zhan XD ... -  《-》

Genomic analysis of prostate cancer stem cells isolated from a highly metastatic cell line.

Rowehl RA ，Crawford H ，Dufour A ，Ju J ，Botchkina GI ... -  《Cancer Genomics & Proteomics》

Small proline-rich protein-1B is overexpressed in human oral squamous cell cancer stem-like cells and is related to their growth through activation of MAP kinase signal.

Cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are considered to be essential for tumor maintenance, recurrence and metastasis. Therefore, eradication of CSCs/CICs is essential to cure cancers. However, the molecular mechanisms of CSCs/CICs are still elusive. In this study, we investigated the molecular mechanism of the cell growth of oral CSCs/CICs. Oral CSCs/CICs were isolated as aldehyde dehydrogenase 1 bright (ALDH1(br)) cells by the ALDEFLUOR assay. Small proline-rich protein-1B (SPRR1B) gene was shown to be overexpressed in ALDH1(br) cells by a cDNA microarray and RT-PCR. SPRR1B was shown to have a role in cell growth and maintenance of ALDH1(br) cells by SPRR1B overexpression and knockdown experiments. To elucidate the molecular mechanism by which SPRR1B regulates cell growth, further cDNA microarray analysis was performed using SPRR1B-overexpressed cells and cells with SPRR1B knocked down by siRNA. Expression of the tumor suppressor gene Ras association domain family member 4 (RASSF4) was found to be suppressed in SPRR1B-overexpressed cells. On the other hand, the expression of RASSF4 was enhanced in cells in which SPRR1B expression was knocked down by SPRR1B-specific siRNA. RASSF4 has an RA (Ras association) domain, and we thus hypothesized that RASSF4 modulates the MAP kinase signal downstream of the Ras signal. MAP kinase signal was activated in SPRR1B-overexpressed cells, whereas the signal was suppressed in SPRR1B knocked down cells. Taken together, the results indicate that the expression of SPRR1B is upregulated in oral CSCs/CICs and that SPRR1B has a role in cell growth by suppression of RASSF4.

Michifuri Y ，Hirohashi Y ，Torigoe T ，Miyazaki A ，Fujino J ，Tamura Y ，Tsukahara T ，Kanaseki T ，Kobayashi J ，Sasaki T ，Takahashi A ，Nakamori K ，Yamaguchi A ，Hiratsuka H ，Sato N ... -  《-》