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Background: Cancer stem cells (CSCs) are responsible for treatment failure. However, their identification and roles in resistance are not well established in head and neck squamous cell carcinoma (HNSCC). Methods: Three HNSCC cell lines (FaDu, Detroit562 and BICR6) were treated with cisplatin or radiation. Cell surface antigens were analysed by LyoPlate, a novel cell surface antigen array. The expression levels of antigens highly expressed after treatments were further compared between cisplatin-resistant Detroit562 cells and its parental line. Association of the candidate antigen with CSCs properties, namely sphere formation and in vivo tumourigenicity, was also examined. Results: CD10, CD15s, CD146 and CD282 were upregulated across the treated cell lines, while the increased expression of CD10 was prominent in the cisplatin-resistant cell line. Isolation mediated by FACS revealed that the CD10-positive subpopulation was more refractory to cisplatin, fluorouracil and radiation than the CD10-negative subpopulation. It also showed an increased ability to form spheres in vitro and tumours in vivo. Moreover, the CD10-positive subpopulation expressed the CSC marker OCT3/4 at a higher level than that in the CD10-negative subpopulation. Conclusions: CD10 is associated with therapeutic resistance and CSC-like properties of HNSCC. CD10 may serve as a target molecule in the treatment of refractory HNSCC.

Cancer is initiated by the transformation of stem cells or progenitor cells via a dedifferentiation process that leads to cancer stem cells; however, the process involves the activation of growth-promoting oncogenes and the inactivation of growth-constraining tumor suppressor genes. The introduction of defined factors, such as those encoded by c-Myc, Sox2, Oct3/4 and Klf4, in normal somatic cells results in their dedifferentiation into induced pluripotent stem (iPS) cells. We previously reported that these defined factors induced the development of induced multipotent cancer (iPC) cells from gastrointestinal cancer cells by reducing tumor aggressiveness. Previous studies indicated that although reprogramming may be facilitated by p53 inhibition, gain-of-function oncogenic mutations in p53 and oncogenic mutations in Kras-stimulated tumorigenic activity, and their roles in vivo are imperfectly understood. Hence, in the present study, the effect of direct injection of a Sendai virus (SeV) vector encoding four defined factors in vivo was studied using various backgrounds of transgenic and knockout mice, and was compared with that of direct injection of microRNAs (miRNAs) diluted with cationic lipid. The in vivo imaging data revealed transformation hot spots for p53 deficiency or conditional activation of mutant Kras, and the sizes were concordant with those in immuno-deficient NOD/SCID and uPA-NOG mice, as well as larger compared with those in the control mice. Overall, the present data on in vivo reprogramming indicated that Kras activation may facilitate the effect of cellular reprogramming in normal liver cells, and the effect of Kras activation is more apparent than that of tumor suppressor p53 deficiency. The results also revealed that immunodeficiency may increase the effect of reprogramming, presumably by blocking the immunosurveillance of transformed cells. These findings provide a rationale for further studies to develop a therapeutic approach involving direct in vivo reprogramming.

A growing body of evidence supports the notion that malignant tumors are heterogeneous and contain diverse subpopulations of cells with unique characteristics including the ability to initiate a tumor and metastasize. This phenomenon might be explained by the so-called cancer stem cell (CSC) theory. Recent technological developments have allowed a deeper understanding and characterization of CSCs. Even though the application of this theory to hematopoietic malignancies and solid tumors holds promise for new ways to treat cancer, it also brings some skepticism. Efficacious therapeutic approaches targeting the CSC population should be explored to overcome therapeutic failure and improve patient outcomes. This review will focus on the intrinsic and extrinsic regulation of CSCs, as well as the development of therapeutic approaches against CSCs, predominantly focusing on gastrointestinal malignancies.

Purpose: One of the main reasons for cancer treatment resistance is the existence of cancer stem-like cells (CSCs). Here, we elucidated the relationship between low proteasome activity cells (LPACs) and CSCs. Experimental Design: The human colorectal cancer cell lines HCT116, SW480, DLD1, and KM12SM were engineered to stably express a green fluorescent molecule fused to the degron of ornithine decarboxylase, resulting in an accumulation of the fluorescence in LPACs. LPACs were isolated by flow cytometry. Treatment resistance (radio- and chemotherapy) and the capacity of LPACs to act as CSCs were analyzed. Microarray analysis was performed to reveal genes related to treatment resistance. The prognostic impact of potent genes was examined in 190 patients with colorectal cancer. Results: LPACs had a significantly increased capacity for radioresistance and chemoresistance (5-fluorouracil and oxaliplatin), significantly lower reactive oxygen species activity, and significantly increased sphere formation capacity compared with non-LPACs. The number of cells in the G0–G1 phase was significantly higher among LPACs. Subcutaneous injection of as few as 20 LPACs led to tumor formation in immunologically incompetent mice. Microarray analysis revealed that the expression of EP300-interacting inhibitor of differentiation 3 (EID3) was significantly increased in LPACs. In vitro assay revealed that EID3 positively controlled cell proliferation and treatment resistance. The high expression of EID3 was an adverse prognostic indicator in patients with colorectal cancer (P = 0.0400). Conclusions: LPACs have characteristic treatment resistance and act as CSCs in colorectal cancer. In addition, EID3 is one of the potential regulators of treatment resistance in colorectal cancer and may be a potential therapeutic target. Clin Cancer Res; 22(21); 5277–86. ©2016 AACR.

Background: The 2012 Nobel Prize success (Gurdon and Yamanaka) gives boost to medical science. While the nuclear transplantation but also the gene transfer of defined factors can elicit cellular reprogramming efficiently in terminally differentiated somatic cells, we have been studied the effects of coding genes (oncogenes [OG], tumor suppressor genes [TSG], and ES-like genes) and non-coding ones (microRNA) on the gastrointestinal cancer cells (reviewed in JAMA, 2001; Cancer Sci, 2008). Compared with known tumor-related genes [OG/TSG], the retroviral-mediated gene transfer of induced pluripotent stem cells (iPSCs) factors, such as Oct4, Sox2, Klf4 and c-Myc resulted in radical modifications of cell lineages, more sensitization to anti-cancer reagents, and significant suppression of tumorigenesis in immunodeficient NOD/SCID mice (PNAS, 2010; BBRC, 2010; IJO, 2012). Given that the viral vectors have potential risks for genome insertion causing carcinogenesis, which would offend clinical application, our extensive screening of ES cell-specific microRNAs allowed the identification of a set of microRNAs (microRNA302 s, 200c and 369 s), which could execute full reprogramming from differentiated cells to iPSCs (Cell Stem Cell, 2011; Cancer Sci, 2011). Here we studied the effect of those microRNAs on gastrointestinal cancer cells in vitro and in vivo. Methods: To inactivate cancer cells, we screened a small set of microRNAs by in vitro experiments, including cell growth, invasion, sphere formation, differentiation assay (three germs) and immunocytochemistry; and in vivo ones, such as chemo-sensitivity, teratoma assay and tumorigenesis. For in vivo assay, synthesized microRNAs were administered intravenously as conjugated forms with carbonate apatite, a novel microRNA delivery technology. The fluorescent labeled microRNAs monitored the efficiency in cancer tissue uptakes as well as the toxicity in normal tissues. Result: 1) Single microRNA302s were able to reprogram colorectal cancer HT29 cells in vitro, as shown by microscopic analysis and qRT-PCR: three germ line differentiation, reduced proliferation and suppressed invasion. 2) Cell fate analysis in vitro demonstrated that ∼60% of HT29 cells reprogrammed, while remaining cells were subjected to apoptosis induction. The reprogrammed cells were sensitized to chemotherapy (fluorouracil). 3) In vivo study showed the microRNA302s effect on tumors, but not on normal tissues, to suppress tumorigenesis significantly in immunodeficient NOD/SCID mice. Conclusion: In vitro and in vivo assay demonstrated clearly that cancer-reprogramming therapy using synthesized microRNAs could modify the cancer cell malignancy, and that the combination with efficient DDS's would facilitate the discovery of innovative cancer therapy. We study further the mechanism microRNA-mediated cancer reprogramming for the drug optimization. Citation Format: Hisataka Ogawa, Hirofumi Yamamoto, Masamitsu Konno, Shin Kure, Susumu Miyazaki, Shinpei Nishikawa, Shinichiro Hasegawa, Katsuya Ohta, Yoshihiro Kano, Takahito Fukusumi, Atsushi Hamabe, Takeshi Yamamoto, Satoshi Obika, Taroh Satoh, Hidetoshi Eguchi, Hiroaki Nagano, Hidenori Inohara, Yuichirou Doki, Masaki Mori, Hideshi Ishii. Cancer reprogramming. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5319. doi:10.1158/1538-7445.AM2013-5319