Genichiro Ishii

Bone-marrow-derived myofibroblasts contribute to the cancer-induced stromal reaction.

To confirm whether human cancer-induced stromal cells are derived from bone marrow, bone marrow (BM) cells obtained from beta-galactosidase transgenic and recombination activating gene 1 (RAG-1) deficient double-mutant mice (H-2b) were transplanted into sublethally irradiated severe combined immunodeficient (SCID) mice (H-2d). The human pancreatic cancer cell line Capan-1 was subcutaneously xenotransplanted into SCID recipients and stromal formation was analyzed on day 14 and on day 28. Immunohistochemical and immunofluorescence studies revealed that BM-derived endothelial cells (X-gal/CD31 or H-2b/CD31 double-positive cells) and myofibroblasts (X-gal/alpha-smooth muscle actin or H-2b/alpha-smooth muscle actin double-positive cells) were present within and around the cancer nests. On day 14, the frequencies of BM-derived endothelial cells and BM-derived myofibroblasts were 25.3+/-4.4% and 12.7+/-9.6%, respectively. On day 28, the frequency of BM-derived endothelial cells was 26.7+/-9.7%, which was similar to the value on day 14. However, the frequency of BM-derived myofibroblasts was significantly higher (39.8+/-17.1%) on day 28 than on day 14 (P<0.05). The topoisomerase IIalpha-positive ratio was 2.2+/-1.2% for the H-2b-positive myofibroblasts, as opposed to only 0.3+/-0.4% for the H-2b-negative myofibroblasts, significant proliferative activity was observed in the BM-derived myofibroblasts (P<0.05). Our results indicate that BM-derived myofibroblasts become a major component of cancer-induced stromal cells in the later stage of tumor development.

Predominant infiltration of macrophages and CD8(+) T Cells in cancer nests is a significant predictor of survival in stage IV nonsmall cell lung cancer.

The purpose of this study was to investigate whether tumor‐infiltrating immune cells in biopsy specimens can be used to predict the clinical outcome of stage IV nonsmall cell lung cancer (NSCLC) patients.

Breast Cancer Resistance Protein Impacts Clinical Outcome in Platinum-Based Chemotherapy for Advanced Non-Small Cell Lung Cancer

Purpose: The purpose of this study was to investigate the relationship between the level of expression of ATP-binding cassette (ABC) transporter proteins, and response to chemotherapy and prognosis in advanced non-small cell lung cancer (NSCLC). Experimental Design: Expression of ABC transporter proteins, including P-glycoprotein, multidrug resistance protein (MRP) 1, MRP2, MRP3, and breast cancer resistance protein (BCRP), was examined immunohistochemically in 72 formalin-fixed tumor samples from untreated stage IIIB or IV NSCLC patients. All of the patients received platinum-based chemotherapy. Response to chemotherapy, progression-free survival (PFS), and overall survival were compared in relation to expression of each of the ABC transporter proteins and clinicopathological factors. Results: Expression of P-glycoprotein, MRP1, and MRP3 was not significantly associated with response to chemotherapy or survival. MRP2 expression was associated with overall survival (P = 0.002) but not with response to chemotherapy and PFS. By contrast, the response rate to chemotherapy of patients with BCRP-negative tumors was 44%, as opposed to 24% in patients with BCRP-positive tumors. Response rate was lower in BCRP-positive tumors, although this difference was not statistically significant (P = 0.08). BCRP-positive patients had also shorter PFS (P = 0.0003) and overall survival (P = 0.004) than BCRP-negative patients. Multivariate analysis confirmed BCRP status as an independent variable related to PFS (P = 0.001). Conclusions: Positive immunostaining for BCRP appears to be a predictor of survival in patients with advanced NSCLC. These findings indicate that BCRP may serve as a molecular target for reducing drug resistance to chemotherapy in advanced NSCLC patients.

Predictive markers for late cervical metastasis in stage I and II invasive squamous cell carcinoma of the oral tongue

Purpose: Patients with oral tongue carcinoma treated by intraoral excision only should be followed up carefully for cervical lymph node metastasis and salvaged immediately if found, because some patients have a more aggressive clinical course. The purpose of this study was to find useful markers for predicting late cervical metastasis in patients with stage I and II invasive squamous cell carcinoma of the oral tongue. Experimental Design: We investigated clinicopathologic factors and immunohistochemical biomarkers predicting late cervical metastasis in surgical specimens from 56 patients with T1–2N0M0 invasive squamous cell carcinoma of the oral tongue who did not undergo elective neck dissection. Histopathologic factors including tumor thickness, mode of invasion, Broders grade, total score of three different malignancy grading systems, eight other clinicopathologic parameters, and immunohistochemical expression of p53, cyclin D1, Ki-67, epidermal growth factor receptor, microvessel density, cyclooxygenase-2, MUC1, laminin-5 γ2, E-cadherin, and β-catenin were examined. All of the clinicopathologic factors and immunohistochemical expression of biomarkers were compared in terms of survival. Results: In the univariate analysis, tumor thickness (P = 0.009), Broders grade (P = 0.017), nest shape (P = 0.005), mode of invasion (P < 0.001), Anneroth score (P = 0.029), Bryne score (P < 0.001), and E-cadherin expression (P = 0.003) were correlated with late cervical metastasis. Multivariate analysis on late cervical metastasis revealed that tumor thickness >4 mm, mode of invasion grade 3 or 4, and E-cadherin expression were independent factors. Late cervical metastasis was the only prognostic factor for overall survival (P = 0.002). Conclusions: Our results indicate that patients with stage I and II invasive squamous cell carcinoma of the oral tongue with tumor thickness >4 mm, mode of invasion grade 3 or 4, and low expression of E-cadherin should be considered a high-risk group for late cervical metastasis when a wait-and-see policy for the neck is adopted.

Autophagy is activated in pancreatic cancer cells and correlates with poor patient outcome.

Because autonomous proliferating cancer cells are often exposed to hypoxic conditions, there must be an alternative metabolic pathway, such as autophagy, that allows them to obtain energy when both oxygen and glucose are depleted. We previously reported finding that autophagy actually contributes to cancer cell survival in colorectal cancers both in vitro and in vivo. Pancreatic cancer remains a devastating and poorly understood malignancy, and hypoxia in pancreatic cancers is known to increase their malignant potential. In the present study archival pancreatic cancer tissue was retrieved from 71 cases treated by curative pancreaticoduodenectomy. Autophagy was evaluated by immunohistochemical staining with anti‐LC3 antibody, as LC3 is a key component of autophagy and has been used as a marker of autophagy. The results showed that strong LC3 expression in the peripheral area of pancreatic cancer tissue was correlated with a poor outcome (P = 0.0170) and short disease‐free period (P = 0.0118). Two of the most significant correlations among the clinicopathological factors tested were found between the peripheral intensity level of LC3 expression and tumor size (P = 0.0098) or tumor necrosis (P = 0.0127). Activated autophagy is associated with pancreatic cancer cells, and autophagy is thought to be a response to factors in the cancer microenvironment, such as hypoxia and poor nutrient supply. This is the first study to report the clinicopathological significance of autophagy in pancreatic cancer. (Cancer Sci 2008; 99: 1813–1819)

Stromal MCP-1 in mammary tumors induces tumor-associated macrophage infiltration and contributes to tumor progression

There is growing evidence that tumor‐associated macrophages (TAMs) promote tumor growth and dissemination. Many individual reports have focused on the protumor function of molecules linked to the recruitment of macrophages, but little is known about which factor has the strongest impact on recruitment of macrophages in breast cancer. To elucidate this question, we performed RT‐PCR using species‐specific primers and evaluated tumoral and stromal mRNA expression of macrophage chemoattractants separately in human breast tumor xenografts. The correlation between the tumoral or stromal chemoattractant mRNA expression including monocyte chemoattractant protein‐1 (MCP‐1) (CCL2), MIP‐1α (CCL3), RANTES (CCL5), colony‐stimulating factor 1, tumor necrosis factor α, platelet‐derived growth factor (PDGF)‐BB and macrophage infiltration were compared. There was significant positive correlation between stromal MCP‐1 expression and macrophage number (r = 0.63), and negative correlation between tumoral RANTES expression and macrophage number (r = −0.75). However, no significant correlation was found for the other tumoral and stromal factors. The interaction between the tumor cells and macrophages was also investigated. Tumor cell–macrophage interactions augmented macrophage‐derived MCP‐1 mRNA expression and macrophage chemotactic activity in vitro. Treatment of immunodeficient mice bearing human breast cancer cells with a neutralizing antibody to MCP‐1 resulted in significant decrease of macrophage infiltration, angiogenetic activity and tumor growth. Furthermore, immunohistochemical analysis of human breast cancer tissue showed stromal MCP‐1 had a significant correlation with relapse free survival (p = 0.029), but tumoral MCP‐1 did not (p = 0.105). These findings indicate that stromal MCP‐1 produced as a result of tumor–stromal interactions may be important for the progression of human breast cancer and macrophages may play an important role in this tumor–stroma interaction.

In Vivo Characterization of Bone Marrow–Derived Fibroblasts Recruited into Fibrotic Lesions

Fibroblasts, which are widely distributed and play a key part in tissue fibrosis, are phenotypically and functionally heterogeneous. Recent studies reported that bone marrow can be a source of tissue fibroblast. In the study reported here, we investigated in vivo characterization of bone marrow–derived fibroblasts recruited into various fibrotic lesions. Mice were engrafted with bone marrow isolated from transgenic mice expressing green fluorescent protein (GFP), and fibrotic lesions were induced by cancer implantation (skin), excisional wounding (skin), and bleomycin administration (lung). A small population of GFP+ fibroblast was found even in nonfibrotic skin (8.7% ± 4.6%) and lung (8.9% ± 2.5%). The proportion of GFP+ fibroblasts was significantly increased after cancer implantation(59.7%±16.3%) and excisional wounding (32.2% ± 4.8%), whereas it was not elevated after bleomycin administration (7.1% ± 2.4%). Almost all GFP+ fibroblasts in fibrotic lesions expressed type I collagen, suggesting that bone marrow–derived fibroblasts would contribute to tissue fibrosis. GFP+ fibroblasts expressed CD45, Thy‐1, and α‐smooth muscle actin at various proportions. Our results suggested that bone marrow–derived fibroblasts expressed several fibroblastic markers in vivo and could be efficiently recruited into fibrotic lesions in response to injurious stimuli; however, the degree of recruitment frequency might depend on the tissue microenvironment.

Podoplanin expression by cancer associated fibroblasts predicts poor prognosis of lung adenocarcinoma

Recent studies have reported increased podoplanin expression by cancer cells and stromal cells, but little is known about its expression and biological significance in adenocarcinoma of the lung. We examined podoplanin expression by both cancer cells and stromal cells in 177 consecutive lung adenocarcinoma cases and analyzed relations between podoplanin expression and both clinicopathological factors and outcome. Podoplanin expression was observed on the apical membrane of the cancer cells in only 9 of the 177 (5.1%) cases. By contrast, cancer‐associated fibroblasts (CAFs) were found to express podoplanin in 54 cases (30.5%). Podoplanin (+) CAFs were found only in invasive adenocarcinoma and none were found in noninvasive adenocarcinoma. Conventional prognostic factors were significantly correlated with podoplanin expression by CAFs. The univariate analyses and log‐rank test showed that podoplanin expression was significantly associated with shorter survival time (p < 0.001 and p < 0.001, respectively). We divided the cases into 3 groups according grade based on the proportion of CAFs expressing podoplanin [a grade 0 group (n = 123), a grade 1 group (n = 36) and a grade 2 group (n = 18)]. The result showed that conventional prognostic factors were significantly correlated with the grade of podoplanin expression by CAFs. Furthermore, the grade 2 group tended to have a shorter survival time than the grade 1 group (p = 0.092). The results of this study highlight the importance of podoplanin expression by CAFs and provide new insights into the biology of the cancer microenvironment in adenocarcinoma of the lung.

Matrix Metalloproteinase-7 Facilitates Insulin-Like Growth Factor Bioavailability through Its Proteinase Activity on Insulin-Like Growth Factor Binding Protein 3

Matrix metalloproteinase-7 (MMP-7) secreted by cancer cells has been implicated classically in the basement membrane destruction associated with tumor cell invasion and metastasis. Recent epidemiologic studies have established a correlation between high levels of circulating insulin-like growth factor (IGF) and low levels of IGF binding protein 3 (IGFBP-3), and relative risk of developing colon, breast, prostate, and lung cancer, which are known to produce MMP-7. In this study, IGFBP-3 was assessed as a candidate for the physiologic substrate of MMP-7. MMP-7 proteolysis generated four major fragments (26 kDa, 17 kDa, 15.5 kDa, and 15.5 kDa), and two cleavage sites were identified: one at the site of hydrolysis of the K144-I145 peptide bond and one at the R95-L96 peptide bond. The former site is different from the previously reported site of cleavage of IGFBP-3 by other proteases. Addition of IGFBP-3 inhibited IGF-I-mediated IGF type 1 receptor (IGF-IR) phosphorylation and activation of the downstream molecule Akt in BALB/c 3T3 fibroblasts overexpressing human IGF-IR (3T3-IGF-IR) and in two human colon cancer cell lines (COLO201 and HT29). Coincubation of the IGF-I/IGFBP-3 complex with MMP-7 restored IGF-I-mediated IGF-IR phosphorylation and activation of Akt in these cell lines. The IGF-I signal recovered by MMP-7 protected against apoptosis induced by anoikis in 3T3-IGF-IR cells. These results indicate that MMP-7 proteolysis of IGFBP-3 plays a crucial role in regulating IGF-I bioavailability, thereby promoting cell survival. This mechanism may contribute to the tumorigenesis of MMP-7-producing IGF-IR-expressing tumors in the primary site and to organ-specific metastasis in a paracrine manner.

Growth Inhibition of Human Prostate Cancer Cells in Human Adult Bone Implanted into Nonobese Diabetic/Severe Combined Immunodeficient Mice by a Ligand-Specific Antibody to Human Insulin-Like Growth Factors

Advanced prostate cancer frequently involves the bone that has the largest content of insulin-like growth factors (IGFs). However, the role of bone-derived IGFs in bone metastasis of prostate cancer has not been studied extensively because of the lack of a reliable animal model. Therefore, we investigated whether a novel antibody directed against human IGF-I and IGF-II (KM1468) could inhibit the development of new bone tumors and the progression of established bone tumors in nonobese diabetic/severe combined immunodeficient mice implanted with human adult bone. We first confirmed that KM1468 bound specifically to human IGF-I, human IGF-II, and mouse IGF-II but not to insulin. It also blocked autophosphorylation of the type I IGF receptor induced by the binding of IGFs in human-type I IGF receptor-overexpressing BALB/c 3T3 cells, and it inhibited the IGF-stimulated growth of MDA PCa 2b cells in vitro. Then mice were injected intraperitoneally with KM1468 once weekly for 4 weeks either immediately or 4 weeks after inoculation of MDA PCa 2b cells. KM1468 markedly and dose-dependently suppressed the development of new bone tumors and the progression of established tumor foci, as determined by histomorphometry, and it also decreased serum prostate-specific antigen levels, compared with the control. This is the first report of an IGF ligand-specific inhibitory antibody that suppresses the growth of human prostate cancer cells in human adult bone. These results indicate that the IGF signaling axis is a potential target for prevention and treatment of bone metastases arising from prostate cancer.