Nagano, O., Okazaki, S. & Saya, H. Redox regulation in stem-like cancer cells by CD44 variant isoforms. Oncogene 32, 5191–5198 (2013).

This review paper describes the discovery of a critical association between a variant form of CD44 (CD44v8-10; recognized by clone RV3 available from Cosmo Bio) and xCT, a subunit of the cystine-glutamate antiporter required for generation of intracellular antioxidant GSH. CD44v8-10 is thought to be a cancer stem cell marker that acts in part by promoting resistance to ROS, thereby accounting for their enhanced resistance to chemo and radiotherapy.

Ohtsuka, J. et al. Functional loss of p53 cooperates with the in vivo microenvironment to promote malignant progression of gastric cancers. Sci Rep 1–15 (2018). doi:10.1038/s41598-018-20572-1

Anti-mouse CD44v monoclonal Ab (Cosmo Bio) was used in immunohistochemical analysis of gastric epithelia and gastric epithelial tumor cells. By 20 weeks of age mice whose gastric mucosa overexpressed Wnt1, Cox2 and microsomal prostaglandin E synthase-1 (Gan mice) developed dysplastic gastric tumors of low malignancy. In this paper the authors crossed Gan mice with p53 KO mice to produce p53 deficient Gan mice. Gastric epithelial cells from p53 KO Gan mice were tumorigenic when transplanted into immunocompetent recipients and serial transfers gradually gave rise to malignant gastric cancer. CD44v expression was noted to increase in p53 KO Gan mouse gastric tumors but to diminish in undifferentiated portions of highly malignant serially transferred tumors.

 Ye, W. et al. Regulation of gastric Lgr5+ve cell homeostasis by Bone Morphogenetic Protein (BMP) signaling and inflammatory stimuli. Cellular and Molecular Gastroenterology and Hepatology 1–53 (2018). doi:10.1016/j.jcmgh.2018.01.007

Anti-mouse CD44v10-e16 rat monoclonal Ab (clone RM1 from Cosmo Bio) was used in immunohistochemical staining of mouse gastric epithelium. Evidence is presented that impaired BMP signaling coupled with Helicobacter felis infection leads to loss of parietal cells and to activation and expansion of a subset of Lgr5 positive chief cells that express CD44v9, a cancer stem cell marker of SPEM known to give rise to gastric carcinogenesis.

Hagiwara, M. et al. Variant isoforms of CD44 involves acquisition of chemoresistance to cisplatin and has potential as a novel indicator for identifying a cisplatin-resistant population in urothelial cancer. 1–11 (2018). doi:10.1186/s12885-018-3988-3

Anti-human CD44v9 rat monoclonal Ab (clone RV3 available from Cosmo Bio) was used in immunohistochemistry of human urothelial cancer tissue and in immunofluorescence staining of human bladder cancer cell lines. Positivity for CD44v9 (CD44v8-10) was shown to be associated with a significantly higher incidence of high grade urothelial tumors. Further, positivity for CD44v9 (CD44v8-10) was also shown to be a strong prognostic indicator of poor cancer specific survival in UC patients treated with CDDP-based chemotherapy and also found to be a significant risk factor for cancer specific mortality.

Using global expression profiling of human osteosarcoma cells and normal fibroblast cell lines, RAB39A was discovered to be a functional cancer stem cell marker whose knockdown and overexpression correlated with loss and gain of in vitro sphere-forming and in vivo xenograft tumor forming ability. Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in flow cytometry of sarcoma cell lines to show that knockdown of RAB39A led to a decrease in the expression of CD44v9. Differential global expression profiling of RAB39A knockdown spheres led to the identification of RXRB as a major downstream effector of RAB39A, suggesting both molecules as therapeutic targets in cancer cells.

Nishino, M. et al. Variant CD44 expression is enriching for a cell population with cancer stem cell-like characteristics in human lung adenocarcinoma. J. Cancer 8, 1774–1785 (2017).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunohistochemistry and flow cytometry to screen multiple lung cancer  cell lines for properties associated with cancer stem cells (CSCs). Staining for aldehyde dehydrogenase (ALDH) was also combined with CD44v9 with the hope of improving the ability to detect CSCs. The results suggest that CD44v9 is a good marker for lung CSCs in human lung adenocarcinoma cell lines. Use of ALDH as second marker provided evidence that lung CSCs may be heterogeneous with different CSC properties distributed over distinct cell subsets.

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used to demonstrate predominant expression of CD44v8-10 in gastric cancer cell lines and advanced gastric tumors. CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was conjugated with near infrared red (NIR) fluors ATTO680 for immunohistochemical detection of CD44v8-10-expressing cells in gastric tumor tissues; and Methylene Blue (MB) for use in in vitro photoimmunotherapy. MB causes not only NIR fluorescence, but also the highly efficient generation of singlet oxygen, thereby selectively killing cancer cells. In mixtures of cell lines either expressing CD44v8-10 or not and stained with MB-conjugated CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) only the CD44v8-10-expressors were subject to photolysis. Together, the results suggest the applicability of CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) for NIR fluorescence detection and photoimmunotherapy of both primary gastric cancer cells and disseminated cancer stem cell-like CD44v8-10(+) cells in the peritoneal cavity in advanced gastric cancer.

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in flow cytometry to sort and analyze the human gall bladder cancer cell line NOZ. The NOZ cell line is shown to comprise two populations that express different CD44 isoforms: CD44s and CD44v9, accounting for 70% and 30% of the CD44+ cells, respectively. Interestingly, the CD44s cells exhibited elevated migration and invasion phenotypes and expressed mesenchymal markers ZEB1, ZEB2 and Vimentin while the CD44v9 cells did not. Instead, they exhibited enhanced tumorigenicity in a mouse xenograft model and expressed high levels of the epithelial marker E-cadherin and the splicing factor ESRP1. Also, subculture of CD44v9 cells gave rise to both CD44v9 and CD44s cells, while subculture of CD44s cells only gave rise to CD44s cells.

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunoblot assays to show that SIRT1 upregulates CD44v9 in ovarian carcinoma cells, correlating with acquisition of enhanced resistance to oxidative stress. Genetic and pharmacological knockdown of SIRT1 downregulated CD44v9 while upregulation led to enhanced CD44v9. The cancer stem cell marker CD44v9 is known to be involved in stabilizing the xCT glutamate-cystine antiporter system that promotes GSH production and protection from ROS.

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used to show that effectiveness of salazosulfapyridine treatment in combination with cisplatin and pemetrexed for advanced non-small-cell lung cancer was associated with an increase in serum CD44v9, likely due to apoptotic death of CD44v9+ CSC. Serum samples collected from 14 patients before and after 21 days of salazosulfapyridine treatment were tested by ELISA for human CD44v9 (from Cosmo Bio).

Miyano, K., Cabral, H., Miura, Y., Matsumoto, Y., Mochida, Y., Kinoh, H., ... & Kataoka, K. (2017). cRGD peptide installation on cisplatin-loaded nanomedicines enhances efficacy against locally advanced head and neck squamous cell carcinoma bearing cancer stem-like cells. Journal of Controlled Release, 261, 275-286.

Ultra low molecular weight hyaluronan is shown to induce features consistent with necrotic cell death in B-precursor leukemia cells that express high levels of CD44. Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in flow cytometry to show that this property did not correlate with the magnitude of ultra-low molecular weight hyaluronan-mediated inhibition of leukemic cells.

FITC-conjugated anti-human CD44s clone SFF-2, APC-conjugated anti-human CD44v9 clone RV3 (Cosmo Bio), APC-conjugated anti-human CD44v3 clone 3G5 and APC-conjugated anti-human CD44v6 clone 2F10 were used in flow cytometry on 5 different human squamous cell carcinoma cell lines to show that after exposure to 60 Gy of irradiation expression of CD44s decreased while variant CD44 expression increased, especially CD44v9. These changes correlated with increased sphere forming ability.

Anti-human CD44v9 rat monoclonal Ab (clone RV3 available from Cosmo Bio) was used in immunohistochemistry to show that patients suffering from either autoimmune or adenocarcinoma-associated chronic atrophic gastritis exhibited elevated CD44v9 expression in spasmolytic polypeptide-expressing metaplastic (SPEM) tissue.                                                                                            .

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunohistochemistry to analyze 103 gastric cancer patient specimens for CD44v9 expression and correlation with five-year recurrence-free survival rate and metabolomic analysis. The results show that high level expression of CD44v9 correlated with significantly lower five-year recurrence-free survival rate and reduced glutathione disulfide levels.

Petersen, C. P., Meyer, A. R., De Salvo, C., Choi, E., Schlegel, C., Petersen, A., ... & Pizarro, T. T. (2017). A signalling cascade of IL-33 to IL-13 regulates metaplasia in the mouse stomach. Gut, gutjnl-2016.

Burclaff, J., Osaki, L. H., Liu, D., Goldenring, J. R., & Mills, J. C. (2017). Targeted apoptosis of parietal cells is insufficient to induce metaplasia in stomach. Gastroenterology, 152(4), 762-766.

Hiraga, T. & Nakamura, H. Comparable roles of CD44v8‑10 and CD44s in the development of bone metastases in a mouse model. Oncol Lett 1–8 (2016). doi:10.3892/ol.2016.4985

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunoblots to confirm the overexpression of CD44v8-10 in lung and breast cancer cell lines. No significant difference was detected in the phenotype of cell lines transfected to overexpress CD44s versus CD44v, in terms of in vitro invasiveness, migration, and tumor sphere formation or on the development of bone metastases.

Kobayashi, K. et al. Clinical significance of CD44 variant 9 expression as a prognostic indicator in bladder cancer. Oncol. Rep. 36, 2852–2860 (2016).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunohistochemistry to assess CD44v9 expression in 98 pathologically confirmed bladder tumor specimens and in two human bladder cancer cell lines. Expression was then correlated with clinical outcome. Elevated CD44v9 expression was correlated with significantly lower progression free and cancer-specific survival rates. In vitro siRNA knockdown of CD44v9 led to lower invasion ability and shorter migration distance, increased expression of the epithelial marker E-cadherin and decreased expression of EMT markers N-cadherin, Snail and Slug.

Matsukuma, S. et al. Calreticulin is highly expressed in pancreatic cancer stem-like cells. Cancer Sci 107, 1599–1609 (2016).

CD44v9-expressing cells from pancreatic cancer cell lines were magnetically enriched using anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) with MACS (Miltenyi) and sorted/analyzed by flow cytometry. Resected pancreatic tumor samples were analyzed by immunohistochemistry for CD44v9-expression. Interestingly, CD44v9 level showed no correlation with clinical outcome.

Sosulski, A. et al. CD44 Splice Variant v8-10 as a Marker of Serous Ovarian Cancer Prognosis. PLoS ONE 11, e0156595–18 (2016).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunohistochemical analysis of a tumor microarray comprising high-grade serous ovarian cancer biopsies. CD44v9 positivity correlated positively with survival. Elevated CD44v9 expression was also shown to correlate with markers of epithelial phenotype, including EPCAM, ESPR1 and E-cadherin.

Thanee, M. et al. CD44 variant-dependent redox status regulation in liver fluke-associated cholangiocarcinoma: A target for cholangiocarcinoma treatment. Cancer Sci 107, 991–1000 (2016).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunohistochemistry and flow cytometry to study CD44 expression in a hamster cholangiocarcinogenesis model and in human cholangiocarcinomas. CD44v8-10 expression inferred from anti-CD44v9 staining was shown to correlate with survival of patients with Opisthorchis viverrini-associated cholangiocarcinoma. Elevated CD44v9 expression also correlated with expression of xCT (part of the glutamate/cystine antiporter important for regeneration of glutathione) and intracellular GSH and downregulation of p38 MAPK-mediated responses to oxidative stress.

Hagiwara, M., Kikuchi, E., Kosaka, T., Mikami, S., Saya, H., & Oya, M. (2016). Variant isoforms of CD44 expression in upper tract urothelial cancer as a predictive marker for recurrence and mortality. In Urologic Oncology: Seminars and Original Investigations (Vol. 34, No. 8, pp. 337-e19). Elsevier.

Wang, M., Miura, Y., Tsuchihashi, K., Miyano, K., Nagano, O., Yoshikawa, M., ... & Saya, H. (2016). Eradication of CD44-variant positive population in head and neck tumors through controlled intracellular navigation of cisplatin-loaded nanomedicines. Journal of Controlled Release, 230, 26-33.

Kakehashi, A. et al. CD44 variant 9 is a potential biomarker of tumor initiating cells predicting survival outcome in hepatitis C virus-positive patients with resected hepatocellular carcinoma. Cancer Sci 107, 609–618 (2016).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 available from Cosmo Bio) and anti-mouse CD44v8-10 (CD44v10-e16 RM1 available from Cosmo Bio) used in immunohistochemical analyses of hepatocellular carcinomas from 90 hepatitis C virus positive patients as well as in diethylnitrosamine-induced hepatocellular carcinomas in C57BL/6 mice. CD44v9 positive cells were predominantly negative for Ki67 and phospho-p38 MAPK expression. CD44v9 expression correlated with poor overall and recurrence-free survival.

Yamada, Y., Miyamoto, T., Kashima, H., Kobara, H., Asaka, R., Ando, H., ... & Shiozawa, T. (2016). Lipocalin 2 attenuates iron-related oxidative stress and prolongs the survival of ovarian clear cell carcinoma cells by up-regulating the CD44 variant. Free radical research, 50(4), 414-425.

Choi, E., Hendley, A. M., Bailey, J. M., Leach, S. D. & Goldenring, J. R. Expression of Activated Ras in Gastric Chief Cells of Mice Leads to the Full Spectrum of Metaplastic Lineage Transitions. Gastroenterology 150, 918–930.e13 (2016).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunohistochemistry to characterize spasmolytic polypeptide expressing metaplastic (SPEM) tissue induced in the stomach by enforced expression of Kras in Chief cells.

Umeda, T., Ishida, M., Murata, S., Mori, T., Kawai, Y., Itoi, N., ... & Kubota, Y. (2016). Immunohistochemical analyses of CD44 variant isoforms in invasive micropapillary carcinoma of the breast: comparison with a concurrent conventional invasive carcinoma of no special type component. Breast Cancer, 23(6), 869-875.

Maruyama, Y., Uehara, T., Daikuhara, S., Kobayashi, Y., Nakajima, T., Matsumoto, A., ... & Ota, H. (2015). Clinicopathological characterisation of duodenal adenocarcinoma with high CD44 variant 9 expression. Pathology, 47(7), 647-652.

Aso, T. et al. Induction of CD44 Variant 9-Expressing Cancer Stem Cells Might Attenuate the Efficacy of Chemoradioselection and Worsens the Prognosis of Patients with Advanced Head and Neck Cancer. PLoS ONE 10, e0116596–14 (2015).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in immunohistochemical analyses to screen head and neck tumor samples from patients that had undergone or not combined chemoradioselection therapy. CD44v9 positivity was significantly correlated with poor prognosis. Furthermore, the survival rate of the CD44v9-induced group was significantly worse than the CD44v9-non-induced group.

Kiuchi, S., Ikeshita, S., Miyatake, Y., & Kasahara, M. (2015). Pancreatic cancer cells express CD44 variant 9 and multidrug resistance protein 1 during mitosis. Experimental and molecular pathology, 98(1), 41-46. NEEDS CONFIRMATION

Ishimoto, T., Izumi, D., Watanabe, M., Yoshida, N., Hidaka, K., Miyake, K., ... & Iwagami, S. (2015). Chronic inflammation with Helicobacter pylori. Journal of gastroenterology, 50(7), 751-757.

Hashimoto, N. et al. Cancer stem-like sphere cells induced from de-differentiated hepatocellular carcinoma-derived cell lines possess the resistance to anti-cancer drugs. BMC Cancer 14, 245–14 (2014).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in flow cytometry to characterize a neural survival factor1 (NSF-1)-supplemented short-term sphere cell culture system that could convert two distinct hepatocellular carcinoma cell lines (one poorly differentiated and the other undifferentiated) into slowly proliferating cancer stem-like cells expressing CDD4v9 and other stem cell markers (Nanog and Lin28) and exhibiting diminished ROS, elevated Hif1a expression and enhanced resistance to a panel of anti-cancer drugs.

Nagano, O., Okazaki, S. & Saya, H. Redox regulation in stem-like cancer cells by CD44 variant isoforms. 32, 5191–5198 (2013).

This review paper describes the discovery of a critical association between a variant form of CD44 (CD44v8-10; recognized by clone RV3 available from Cosmo Bio) and xCT, a subunit of the cystine-glutamate antiporter required for generation of intracellular antioxidant GSH. CD44v8-10 is thought to be a cancer stem cell marker that acts in part by promoting resistance to ROS, thereby accounting for their enhanced resistance to chemo and radiotherapy.

Tsugawa, H. et al. Reactive oxygen species-induced autophagic degradation of Helicobacter pylori CagA is specifically suppressed in cancer stem-like cells. Cell Host Microbe 12, 764–777 (2012).

Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was used in flow cytometry to delineate expression of CD44v9 by CD44 negative MKN28 cells transfected with CD44v9 or CD44s, prior to assessing their response to infection with Helicobacter pylori. Anti-human CD44v9 rat monoclonal Ab (clone RV3 from Cosmo Bio) was also used in fluorescent immunohistochemistry on patient derived gastric adenocarcinomas.

Masuko, K. et al. Anti-Tumor Effect against Human Cancer Xenografts by a Fully Human Monoclonal Antibody to a Variant 8-Epitope of CD44R1 Expressed on Cancer Stem Cells. PLoS ONE 7, e29728–12 (2012).

This is one of 3 papers where a description can be found of the construction of human CD44v9 rat monoclonal Ab (clone RV3 available from Cosmo Bio). Female F344 rats were repeatedly injected subcutaneously and intraperitoneally with RH7777 cells expressing human CD44v8-10 linked to green fluorescent protein. Specificity was assessed by enzyme-linked immunosorbent assay using the recombinant variant exon-9 region of the CD44v protein. The study describes the construction and validation of:

GV5 (fully humanized) IgG mAb against CD44v8
RV3 rat mAb against human CD44v9
RV7 rat mAb against human CD44s
RV9 rat mAb against human CD44v8

GV5 is shown to inhibit the growth of human cancer xenografts in athymic mice.

Ishimoto, T. et al. CD44 Variant Regulates Redox Status in Cancer Cells by Stabilizing the xCT Subunit of System xc- and Thereby Promotes Tumor Growth. Cancer Cell 19, 387–400 (2011).

This is one of 3 papers where a description can be found of the construction of human CD44v9 rat monoclonal Ab (clone RV3 available from Cosmo Bio). Female F344 rats were repeatedly injected subcutaneously and intraperitoneally with RH7777 cells expressing human CD44v8-10 linked to green fluorescent protein. Specificity was assessed by enzyme-linked immunosorbent assay using the recombinant variant exon-9 region of the CD44v protein. This landmark study shows that high levels of CD44v8-10 expressed on gastrointestinal tumor cells confer elevated intracellular GSH and resistance to damage from ROS. This is due to CD44v8-10-dependent recruitment of the xCT subunit of the System xc- antiporter responsible for importing cystine in exchange for glutamate, critical for the regeneration of GSH.

Ishimoto, T. et al. CD44 +slow-cycling tumor cell expansion is triggered by cooperative actions of Wnt and prostaglandin E 2in gastric tumorigenesis. Cancer Sci 101, 673–678 (2010).

This is one of 3 papers where a description can be found of the construction of human CD44v9 rat monoclonal Ab (clone RV3 available from Cosmo Bio). Female F344 rats were repeatedly injected subcutaneously and intraperitoneally with RH7777 cells expressing human CD44v8-10 linked to green fluorescent protein. Specificity was assessed by enzyme-linked immunosorbent assay using the recombinant variant exon-9 region of the CD44v protein. This study describes the discovery of a patch of slow cycling glandular cells residing at the squamous/columnar junction of the mouse stomach. These CD44+ cells expand in response to PGE2 and Wnt signaling in a model of gastric carcinogenesis.