Prospective study of adoptive activated αßT lymphocyte immunotherapy for refractory cancers: development and validation of a response scoring system.

BACKGROUND AIMS: This prospective clinical study aimed to determine the efficacy and prognostic factors of adoptive activated αßT lymphocyte immunotherapy for various refractory cancers. The primary endpoint was overall survival (OS), and the secondary endpoint was radiological response. METHODS: The authors treated 96 patients. Activated αßT lymphocytes were infused every 2 weeks for a total of six times. Prognostic factors were identified by analyzing clinical and laboratory data obtained before therapy. RESULTS: Median survival time (MST) was 150 days (95% confidence interval, 105-191), and approximately 20% of patients achieved disease control (complete response + partial response + stable disease). According to the multivariate Cox proportional hazards model with Akaike information criterion-best subset selection, sex, concurrent therapy, neutrophil/lymphocyte ratio, albumin, lactate dehydrogenase, CD4:CD8 ratio and T helper (Th)1:Th2 ratio were strong prognostic factors. Using parameter estimates of the Cox analysis, the authors developed a response scoring system. The authors then determined the threshold of the response score between responders and non-responders. This threshold was able to significantly differentiate OS of responders from that of non-responders. MST of responders was longer than that of non-responders (317.5 days versus 74 days). The validity of this response scoring system was then confirmed by internal validation. CONCLUSIONS: Adoptive activated αßT lymphocyte immunotherapy has clinical efficacy in certain patients. The authors' scoring system is the first prognostic model reported for this therapy, and it is useful for selecting patients who might obtain a better prognosis through this modality.

Inhibition of dopamine receptor D1 signaling promotes human bile duct cancer progression via WNT signaling.

Bile duct cancer (BDC) frequently invades the nerve fibers, making complete surgical resection difficult. A single tumor mass contains cells of variable malignancy and cell-differentiation states, with cancer stem cells (CSCs) considered responsible for poor clinical outcomes. This study aimed to investigate the contribution of autosynthesized dopamine to CSC-related properties in BDC. Sphere formation assays using 13 commercially available BDC cell lines demonstrated that blocking dopamine receptor D1 (DRD1) signaling promoted CSC-related anchorage-independent growth. Additionally, we newly established four new BDC patient-derived organoids (PDOs) and found that blocking DRD1 increased resistance to chemotherapy and enabled xenotransplantation in vivo. Single-cell analysis revealed that the BDC PDO cells varied in their cell-differentiation states and responses to dopamine signaling. Further, DRD1 inhibition increased WNT7B expression in cells with bile duct-like phenotype, and it induced proliferation of other cell types expressing Wnt receptors and stem cell-like signatures. Reagents that inhibited Wnt function canceled the effect of DRD1 inhibition and reduced cell proliferation in BDC PDOs. In summary, in BDCs, DRD1 is a crucial protein involved in autonomous CSC proliferation through the regulation of endogenous WNT7B. As such, inhibition of the DRD1 feedback signaling may be a potential treatment strategy for BDC.

JNK pathway plays a critical role for expansion of human colorectal cancer in the context of BRG1 suppression.

Tumor stem cells (TSCs), capable of self-renewal and continuous production of progeny cells, could be potential therapeutic targets. We have recently reported that chromatin remodeling regulator Brg1 is required for maintenance of murine intestinal TSCs and stemness feature of human colorectal cancer (CRC) cells by inhibiting apoptosis. However, it is still unclear how BRG1 suppression changes the underlying intracellular mechanisms of human CRC cells. We found that Brg1 suppression resulted in upregulation of the JNK signaling pathway in human CRC cells and murine intestinal TSCs. Simultaneous suppression of BRG1 and the JNK pathway, either by pharmacological inhibition or silencing of c-JUN, resulted in even stronger inhibition of the expansion of human CRC cells compared to Brg1 suppression alone. Consistently, high c-JUN expression correlated with worse prognosis for survival in human CRC patients with low BRG1 expression. Therefore, the JNK pathway plays a critical role for expansion and stemness of human CRC cells in the context of BRG1 suppression, and thus a combined blockade of BRG1 and the JNK pathway could be a novel therapeutic approach against human CRC.

Establishment of patient-derived organoids and a characterization-based drug discovery platform for treatment of pancreatic cancer.

BACKGROUND: Pancreatic cancer is one of the most lethal tumors. The aim of this study is to provide an effective therapeutic discovery platform for pancreatic cancer by establishing and characterizing patient-derived organoids (PDOs). METHODS: PDOs were established from pancreatic tumor surgical specimens, and the mutations were examined using a panel sequence. Expression of markers was assessed by PCR, immunoblotting, and immunohistochemistry; tumorigenicity was examined using immunodeficient mice, and drug responses were examined in vitro and in vivo. RESULTS: PDOs were established from eight primary and metastatic tumors, and the characteristic mutations and expression of cancer stem cell markers and CA19-9 were confirmed. Tumorigenicity of the PDOs was confirmed in subcutaneous transplantation and in the peritoneal cavity in the case of PDOs derived from disseminated nodules. Gemcitabine-sensitive/resistant PDOs showed consistent responses in vivo. High throughput screening in PDOs identified a compound effective for inhibiting tumor growth of a gemcitabine-resistant PDO xenograft model. CONCLUSIONS: This PDO-based platform captures important aspects of treatment-resistant pancreatic cancer and its metastatic features, suggesting that this study may serve as a tool for the discovery of personalized therapies.

SNAIL2 contributes to tumorigenicity and chemotherapy resistance in pancreatic cancer by regulating IGFBP2.

Pancreatic cancer has an extremely poor prognosis because of its resistance to conventional therapies. Cancer stem cell (CSC)-targeted therapy is considered a promising approach for this disease. Epithelial-mesenchymal transition-inducing transcription factors (EMT-TFs) contribute to CSC properties in some solid tumors; however, this mechanism has not been fully elucidated in pancreatic cancer. Zinc finger protein, SNAIL2 (also known as SLUG), is a member of the SNAIL superfamily of EMT-TFs and is commonly overexpressed in pancreatic cancer. Patients exhibiting high SNAIL2 expression have a poor prognosis. In this study, we showed that the suppression of SNAIL2 expression using RNA interference decreased tumorigenicity in vitro (sphere formation assay) and in vivo (xenograft assay) in 2 pancreatic cancer cell lines, KLM1 and KMP5. In addition, SNAIL2 suppression resulted in increased sensitivity to gemcitabine and reduced the expression of CD44, a pancreatic CSC marker. Moreover, experiments on tumor spheroids established from surgically resected pancreatic cancer tissues yielded similar results. A microarray analysis revealed that the mechanism was mediated by insulin-like growth factor (IGF) binding protein 2. These results indicate that IGFBP2 regulated by SNAIL2 may represent an effective therapeutic target for pancreatic cancer.

Brg1 is required to maintain colorectal cancer stem cells.

Tumor cells capable of self-renewal and continuous production of progeny cells are called tumor stem cells (TSCs) and are considered to be potential therapeutic targets. However, the mechanisms underlying the survival and function of TSCs are not fully understood. We previously reported that chromatin remodeling regulator Brg1 is essential for intestinal stem cells in mice and Dclk1 is an intestinal TSC marker. In this study, we investigated the role of Brg1 in Dclk1+ intestinal tumor cells for the maintenance of intestinal tumors in mice. Specific ablation of Brg1 in Dclk1+ intestinal tumor cells reduced intestinal tumors in ApcMin mice, and continuous ablation of Brg1 maintained the reduction of intestinal tumors. Lineage tracing in the context of Brg1 ablation in Dclk1+ intestinal tumor cells revealed that Brg1-null Dclk1+ intestinal tumor cells did not give rise to their descendent tumor cells, indicating that Brg1 is essential for the self-renewal of Dclk1+ intestinal tumor cells. Five days after Brg1 ablation, we observed increased apoptosis in Dclk1+ tumor cells. Furthermore, Brg1 was crucial for the stemness of intestinal tumor cells in a spheroid culture system. BRG1 knockdown also impaired cell proliferation and increased apoptosis in human colorectal cancer (CRC) cells. Microarray analysis revealed that apoptosis-related genes were upregulated and stem cell-related genes were downregulated in human CRC cells by BRG1 suppression. Consistently, high BRG1 expression correlated with poor disease-specific survival in human CRC patients. These data indicate that Brg1 plays a crucial role in intestinal TSCs in mice by inhibiting apoptosis and is critical for cell survival and stem cell features in human CRC cells. Thus, BRG1 represents a new therapeutic target for human CRC. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

SNAIL regulates gastric carcinogenesis through CCN3 and NEFL.

Among cancer cells, there are specific cell populations of whose activities are comparable to those of stem cells in normal tissues, and for whom the levels of cell dedifferentiation are reported to correlate with poor prognosis. Information concerning the mechanisms that modulate the stemness like traits of cancer cells is limited. Therefore, we examined five gastric cancer cell lines and isolated gastric oncospheres from three gastric cancer cell lines. The gastric cancer cells that expanded in the spheres expressed relatively elevated proportion of CD44, which is a marker of gastric cancer stem cells (CSCs), and displayed many properties of CSCs, for example: chemoresistance, tumorigenicity and epithelial-mesenchymal transition (EMT) acquisition. SNAIL, which is a key factor in EMT, was highly expressed in the gastric spheres. Microarray analysis in gastric cancer cell line HGC27 showed that CCN3 and NEFL displayed the greatest differential expression by knocking down of SNAIL; the former was upregulated and the latter downregulated, respectively. Downregulation of CCN3 and upregulation of NEFL gene expression impaired the SNAIL-dependent EMT activity: high tumorigenicity, and chemoresistance in gastric cancer cells. Thus, approach that disrupts SNAIL/CCN3/NEFL axis may be credible in inhibiting gastric cancer development.

Promoter-Level Transcriptome Identifies Stemness Associated With Relatively High Proliferation in Pancreatic Cancer Cells.

Both pancreatic intraepithelial neoplasia (PanIN), a frequent precursor of pancreatic cancer, and intraductal papillary mucinous neoplasm (IPMN), a less common precursor, undergo several phases of molecular conversions and finally develop into highly malignant solid tumors with negative effects on the quality of life. We approached this long-standing issue by examining the following PanIN/IPMN cell lines derived from mouse models of pancreatic cancer: Ptf1a-Cre; KrasG12D; p53f/+ and Ptf1a-Cre; KrasG12D; and Brg1f/f pancreatic ductal adenocarcinomas (PDAs). The mRNA from these cells was subjected to a cap analysis of gene expression (CAGE) to map the transcription starting sites and quantify the expression of promoters across the genome. Two RNA samples extracted from three individual subcutaneous tumors generated by the transplantation of PanIN or IPMN cancer cell lines were used to generate libraries and Illumina Seq, with four RNA samples in total, to depict discrete transcriptional network between IPMN and PanIN. Moreover, in IPMN cells, the transcriptome tended to be enriched for suppressive and inhibitory biological processes. In contrast, the transcriptome of PanIN cells exhibited properties of stemness. Notably, the proliferation capacity of the latter cells in culture was only minimally constrained by well-known chemotherapy drugs such as GSK690693 and gemcitabine. The various transcriptional factor network systems detected in PanIN and IPMN cells reflect the distinct molecular profiles of these cell types. Further, we hope that these findings will enhance our mechanistic understanding of the characteristic molecular alterations underlying pancreatic cancer precursors. These data may provide a promising direction for therapeutic research.

Arid1a is essential for intestinal stem cells through Sox9 regulation.

Inactivating mutations of Arid1a, a subunit of the Switch/sucrose nonfermentable chromatin remodeling complex, have been reported in multiple human cancers. Intestinal deletion of Arid1a has been reported to induce colorectal cancer in mice; however, its functional role in intestinal homeostasis remains unclear. We investigated the functional role of Arid1a in intestinal homeostasis in mice. We found that intestinal deletion of Arid1a results in loss of intestinal stem cells (ISCs), decreased Paneth and goblet cells, disorganized crypt-villous structures, and increased apoptosis in adult mice. Spheroids did not develop from intestinal epithelial cells deficient for Arid1a Lineage-tracing experiments revealed that Arid1a deletion in Lgr5+ ISCs leads to impaired self-renewal of Lgr5+ ISCs but does not perturb intestinal homeostasis. The Wnt signaling pathway, including Wnt agonists, receptors, and target genes, was strikingly down-regulated in Arid1a-deficient intestines. We found that Arid1a directly binds to the Sox9 promoter to support its expression. Remarkably, overexpression of Sox9 in intestinal epithelial cells abrogated the above phenotypes, although Sox9 overexpression in intestinal epithelial cells did not restore the expression levels of Wnt agonist and receptor genes. Furthermore, Sox9 overexpression permitted development of spheroids from Arid1a-deficient intestinal epithelial cells. In addition, deletion of Arid1a concomitant with Sox9 overexpression in Lgr5+ ISCs restores self-renewal in Arid1a-deleted Lgr5+ ISCs. These results indicate that Arid1a is indispensable for the maintenance of ISCs and intestinal homeostasis in mice. Mechanistically, this is mainly mediated by Sox9. Our data provide insights into the molecular mechanisms underlying maintenance of ISCs and intestinal homeostasis.

Nardilysin inhibits pancreatitis and suppresses pancreatic ductal adenocarcinoma initiation in mice.

OBJECTIVE: Nardilysin (NRDC), a zinc peptidase, exhibits multiple localisation-dependent functions including as an enhancer of ectodomain shedding in the extracellular space and a transcriptional coregulator in the nucleus. In this study, we investigated its functional role in exocrine pancreatic development, homeostasis and the formation of pancreatic ductal adenocarcinoma (PDA). DESIGN: We analysed Ptf1a-Cre; Nrdcflox/flox mice to investigate the impact of Nrdc deletion. Pancreatic acinar cells were isolated from Nrdcflox/flox mice and infected with adenovirus expressing Cre recombinase to examine the impact of Nrdc inactivation. Global gene expression in Nrdc-cKO pancreas was analysed compared with wild-type pancreas by microarray analysis. We also analysed Ptf1a-Cre; KrasG12D; Nrdcflox/flox mice to investigate the impact of Nrdc deletion in the context of oncogenic Kras. A total of 51 human samples of pancreatic intraepithelial lesions (PanIN) and PDA were examined by immunohistochemistry for NRDC. RESULTS: We found that pancreatic deletion of Nrdc leads to spontaneous chronic pancreatitis concomitant with acinar-to-ductal conversion, increased apoptosis and atrophic pancreas in mice. Acinar-to-ductal conversion was observed mainly through a non-cell autonomous mechanism, and the expression of several chemokines was significantly increased in Nrdc-null pancreatic acinar cells. Furthermore, pancreatic deletion of Nrdc dramatically accelerated KrasG12D -driven PanIN and subsequent PDA formation in mice. These data demonstrate a previously unappreciated anti-inflammatory and tumour suppressive functions of Nrdc in the pancreas in mice. Finally, absence of NRDC expression was observed in a subset of human PanIN and PDA. CONCLUSION: Nrdc inhibits pancreatitis and suppresses PDA initiation in mice.

A peptide inhibitor of antibody-dependent cell-mediated cytotoxicity against EGFR/folate receptor-α double positive cells.

Antibody-dependent cell-mediated cytotoxicity (ADCC) is caused by natural killer (NK) cells upon recognition of antigen-bound IgG via FcγRIIIa. This mechanism is crucial for cytolysis of pathogen-infected cells and monoclonal antibody (mAb)-mediated elimination of cancer cells. However, there is concern that mAb-based cancer therapy induces ADCC against non-target cells expressing antigens. To date, no strategy has been reported to enhance the selectivity of ADCC to protect non-target cells expressing antigens. Here, we introduce a model inhibitor which specifically blocks ADCC of anti-EGFR mAbs towards EGFR/folate receptor α (FRα) double positive cells. This inhibitor recruits mAbs on the FRα of the cell surface independent of Fab antigen recognition. The resulting ternary and/or quaternary complexes formed on the cell surface suppress signal transduction of FcγRIIIa in NK cells, consequently leading to more specific ADCC.

E­cadherin regulates proliferation of colorectal cancer stem cells through NANOG.

Cancer stem cells (CSCs) possess a self­renewal ability and display tumorigenic potential in immunodeficient mice. Colorectal CSCs are thought to be a uniform population and no functionally distinct subpopulations have been identified. Because E­cadherin is an essential molecule for self­renewal of embryonic stem cells, we examined E­cadherin expression, which may play a role in maintaining the properties of CSCs, in EpCAMhigh/CD44+ colorectal CSCs from human primary colorectal cancers. We obtained 18 surgical specimens of human primary colorectal cancer. CD44, EpCAM, and E­cadherin expression were analyzed by fluorescence­activated cell sorting. Sorted EpCAMhigh/CD44+ colorectal CSCs were injected into immunodeficient mice to estimate the tumorigenic potential. Genetic profiles were analyzed by cDNA microarray. Notably, colorectal CSCs could be divided into two populations based on the E­cadherin expression status, and they exhibited different pathological characteristics. Compared to E­cadherin­negative colorectal CSCs, E­cadherin­positive (EC+) colorectal CSCs demonstrated higher tumor growth potential in vivo. EC+ colorectal CSCs revealed a higher expression of the pluripotency factor NANOG, which contributed to the higher tumor growth potential of EC+ colorectal CSCs through control of cyclin D1 expression. These findings are the first demonstration of functionally distinct subpopulations of colorectal CSCs in human clinical samples.

Natural killer (NK) cell and immunotherapy.

Natural killer (NK) cells are innate lymphoid cells important for host defense against patho- gens, and are also thought to play an important role in the immunosurveillance against can- cers. NK cells express surface receptors that interact with target cells and determine their response to infected or transformed cells without prior sensitization or gene rearrangement. Activated NK cells can kill target cells by producing effector molecules and transmit impor- tant information to the rest of the immune system subsequently by producing cytokines. Here, we review the mechanism of cytotoxic function of NK cells and a recent development in NK cell biology, and highlight therapeutic approaches for NK cell-based immunotherapy and targeting NK cells in the treatment of cancer. //.

Clinical outcomes of a novel therapeutic vaccine with Tax peptide-pulsed dendritic cells for adult T cell leukaemia/lymphoma in a pilot study.

Adult T cell leukaemia/lymphoma (ATL) is a human T cell leukaemia virus type-I (HTLV-I)-infected T cell malignancy with poor prognosis. We herein developed a novel therapeutic vaccine designed to augment an HTLV-I Tax-specific cytotoxic T lymphocyte (CTL) response that has been implicated in anti-ATL effects, and conducted a pilot study to investigate its safety and efficacy. Three previously treated ATL patients, classified as intermediate- to high-risk, were subcutaneously administered with the vaccine, consisting of autologous dendritic cells (DCs) pulsed with Tax peptides corresponding to the CTL epitopes. In all patients, the performance status improved after vaccination without severe adverse events, and Tax-specific CTL responses were observed with peaks at 16-20 weeks. Two patients achieved partial remission in the first 8 weeks, one of whom later achieved complete remission, maintaining their remission status without any additional chemotherapy 24 and 19 months after vaccination, respectively. The third patient, whose tumour cells lacked the ability to express Tax at biopsy, obtained stable disease in the first 8 weeks and later developed slowly progressive disease although additional therapy was not required for 14 months. The clinical outcomes of this pilot study indicate that the Tax peptide-pulsed DC vaccine is a safe and promising immunotherapy for ATL.

CCK2R identifies and regulates gastric antral stem cell states and carcinogenesis.

OBJECTIVE: Progastrin is the incompletely cleaved precursor of gastrin that is secreted by G-cells in the gastric antrum. Both gastrin and progastrin bind to the CCK2 receptor (Cckbr or CCK2R) expressed on a subset of gastric epithelial cells. Little is known about how gastrin peptides and CCK2R regulate gastric stem cells and carcinogenesis. Interconversion among progenitors in the intestine is documented, but the mechanisms by which this occurs are poorly defined. DESIGN: We generated CCK2R-CreERT mice and performed inducible lineage tracing experiments. CCK2R+ antral cells and Lgr5+ antral stem cells were cultured in a three-dimensional in vitro system. We crossed progastrin-overexpressing mice with Lgr5-GFP-CreERT mice and examined the role of progastrin and CCK2R in Lgr5+ stem cells during MNU-induced carcinogenesis. RESULTS: Through lineage tracing experiments, we found that CCK2R defines antral stem cells at position +4, which overlapped with an Lgr5(neg or low) cell population but was distinct from typical antral Lgr5(high) stem cells. Treatment with progastrin interconverts Lgr5(neg or low) CCK2R+ cells into Lgr5(high) cells, increases CCK2R+ cell numbers and promotes gland fission and carcinogenesis in response to the chemical carcinogen MNU. Pharmacological inhibition or genetic ablation of CCK2R attenuated progastrin-dependent stem cell expansion and carcinogenesis. CONCLUSIONS: CCK2R labels +4 antral stem cells that can be activated and expanded by progastrin, thus identifying one hormonal trigger for gastric stem cell interconversion and a potential target for gastric cancer chemoprevention and therapy.

Analysis of adverse events of bevacizumab-containing systemic chemotherapy for metastatic colorectal cancer in Japan.

BACKGROUND: Bevacizumab (BV) is widely used in chemotherapy for metastatic colorectal cancer (mCRC). Although specific adverse events have been observed, their risk factors have not been clarified. PATIENTS AND METHODS: 178 mCRC patients who underwent chemotherapy were retrospectively examined and correlations between possible risk factors and adverse events were analyzed. RESULTS: 87 out of 178 patients were treated with BV-containing chemotherapy. Possible risk factors for BV-related adverse events were: remaining primary tumor, current bleeding, history of arterial thromboembolism (ATE), hypertension, and proteinuria, and these were observed in 22%, 2%, 7%, 16%, and 8% of patients, respectively. Patients with hypertension prior to chemotherapy developed significantly worse hypertension (p=0.018). Gastrointestinal bleeding occurred in 3 out of 18 patients with residual primary tumor (16.7%) and 6 out of 63 patients with no primary tumor (8.7%) (p=0.385). CONCLUSION: Pre-existing hypertension appears to be a risk factor for BV-related deterioration of hypertension.

Efficacy and safety of an increased-dose of dexamethasone in patients receiving fosaprepitant chemotherapy in Japan.

BACKGROUND: Antiemetic triplet therapy including dexamethasone (DEX) is widely used for patients receiving highly emetogenic chemotherapy (HEC). In Japan, the appropriate dose of DEX has not been established for this combination. MATERIALS AND METHODS: To assess the efficacy and safety of increased-dose DEX, we retrospectively examined patients receiving HEC with antiemetic triplet therapy. RESULTS: Twenty-four patients (fosaprepitant group) were given an increased-dose of DEX (average total dose: 45.8mg), fosaprepitant, and 5-HT3 antagonist. A lower-dose of DEX (33.6mg), oral aprepitant, and 5-HT3 antagonist were administered to the other 48 patients (aprepitant group). The vomiting control rates in the fosaprepitant and aprepitant groups were 100% and 85.4% in the acute phase, and were 75.0% and 64.6% in the delayed phase. The incidences of toxicity were similar comparing the two groups. CONCLUSIONS: Triplet therapy using an increased-dose of DEX is suggested to be safe and effective for patients receiving HEC.

Pemetrexed combined with platinum-based chemotherapy for advanced malignant peritoneal mesothelioma: retrospective analysis of six cases.

BACKGROUND: Malignant peritoneal mesothelioma (PM) is an extremely rare disease. Pemetrexed and platinum have been used for advanced PM following malignant pleural mesothelioma (PLM). Because PM differs considerably from PLM in clinical features, the efficacy and safety of these therapies have yet to be established. PATIENTS AND METHODS: Six Japanese patients with PM who had been treated with pemetrexed-based chemotherapy in four Institutions were retrospectively identified. Treatment response, progression-free survival, and overall survival were examined. Toxicities of therapy were also evaluated. RESULTS: Three patients with mild ascites achieved clinical benefits (one with partial response and two with stable disease). Treatments with reduced cisplatin or carboplatin for patients with massive ascites were safely performed. Median PFS and OS were 7.2 and 13.1 months, respectively. Grade 3 hematological toxicities appeared in two patients with massive ascites. CONCLUSION: Selection of chemotherapy based on the patient's condition, such as ascites, might be important for advanced PM.

P53 gene mutation increases progastrin dependent colonic proliferation and colon cancer formation in mice.

Transgenic mice overexpressing human progastrin (hGAS) show colonic crypt hyper-proliferation and elevated susceptibility to colon carcinogenesis. We aimed to investigate effects of p53 mutation on colon carcinogenesis in hGAS mice. We show that introducing a p53 gene mutation further increases progastrin dependent BrdU labeling and results in markedly elevated number of aberrant crypt foci (ACF) and colonic tumors. We demonstrate that hGAS/Lgr5-GFP mice have higher number of Lgr5+ colonic stem cells per crypt when compared to Lgr5-GFP mice indicating that progastrin changes crypt biology through increased stem cell numbers and additional p53 mutation leads to more aggressive phenotype in this murine colon cancer model.

Human STEAP3 maintains tumor growth under hypoferric condition.

Iron is essential in cellular proliferation and survival based on its crucial roles in DNA and ATP synthesis. Tumor cells proliferate rapidly even in patients with low serum iron, although their actual mechanisms are not well known. To elucidate molecular mechanisms of efficient tumor progression under the hypoferric condition, we studied the roles of six-transmembrane epithelial antigen of the prostate family member 3 (STEAP3), which was reported to facilitate iron uptake. Using Raji cells with low STEAP3 mRNA expression, human STEAP3-overexpressing cells were established. The impact of STEAP3 expression was analyzed about the amount of iron storage, the survival under hypoferric conditions in vitro and the growth of tumor in vivo. STEAP3 overexpression increased ferritin, an indicator of iron storage, in STEAP3-overexpressing Raji cells. STEAP3 gave Raji cells the resistance to iron deprivation-induced apoptosis. These STEAP3-overexpressing Raji cells preserved efficient growth even in hypoferric mice, while parental Raji cells grew less rapidly. In addition, iron deficiency enhanced STEAP3 mRNA expression in tumor cells. Furthermore, human colorectal cancer tissues exhibited more STEAP3 mRNA expression and iron storage compared with normal colon mucosa. These findings indicate that STEAP3 maintains iron storage in human malignant cells and tumor proliferation under the hypoferric condition.