Lactic acid promotes PD-1 expression in regulatory T cells in highly glycolytic tumor microenvironments

The balance of programmed death-1 (PD-1)-expressing CD8⁺ T cells and regulatory T (Treg) cells in the tumor microenvironment (TME) determines the clinical efficacy of PD-1 blockade therapy through the competition of their reactivation. However, factors that determine this balance remain unknown. Here, we show that Treg cells gain higher PD-1 expression than effector T cells in highly glycolytic tumors, including MYC-amplified tumors and liver tumors. Under low-glucose environments via glucose consumption by tumor cells, Treg cells actively absorbed lactic acid (LA) through monocarboxylate transporter 1 (MCT1), promoting NFAT1 translocation into the nucleus, thereby enhancing the expression of PD-1, whereas PD-1 expression by effector T cells was dampened. PD-1 blockade invigorated the PD-1-expressing Treg cells, resulting in treatment failure. We propose that LA in the highly glycolytic TME is an active checkpoint for the function of Treg cells in the TME via upregulation of PD-1 expression.

Phenotypic and functional heterogeneity of cancer-associated fibroblast within the tumor microenvironment

Cancer microenvironment is created not only by malignant epithelial cells, but also by several kinds of stromal cells. Since Paget proposed the "seed and soil" hypothesis, the biological importance of the cancer microenvironment has come to be widely accepted. The main compartment of host stromal cells are fibroblasts (Cancer-Associated Fibroblasts; CAFs), which are the main source of the collagen-producing cells. CAFs directly communicate with the cancer cells and other types of stromal cells to acquire a specific biological phenotype. CAFs play important roles in several aspects of the tumor progression process and the chemotherapeutic process. However, CAFs have heterogeneous origins, phenotypes, and functions under these conditions. A crucial challenge is to understand how much of this heterogeneity serves different biological responses to cancer cells. In this review, we highlight the issue of how diverse and heterogeneous functions given by CAFs can exert potent influences on tumor progression and therapeutic response. Furthermore, we also discuss the current advances in the development of novel therapeutic strategies against CAFs.

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

BACKGROUND

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.

METHOD

The authors performed an immunohistochemical study to identify and count the number of CD68(+) macrophages, c-kit(+) mast cells, and CD8(+) T cells in both cancer nests and cancer stroma in pretreatment biopsy specimens obtained from 199 patients with stage IV NSCLC treated by chemotherapy, and then analyzed for correlations between the number of immune cells and clinical outcome, including chemotherapy response and prognosis.

RESULTS

There was no correlation between the number of immune cells in either cancer nests or stroma and chemotherapy response. Patients with more tumor-infiltrating macrophages in cancer nests than in cancer stroma (macrophages, nests > stroma) had significantly better survival than nests < stroma cases median survival time (MST 440 days vs 199 days; P < .0001). Patients with more tumor-infiltrating CD8(+) T cells in cancer nests than in cancer stroma (CD8(+) T cells: nests > stroma) showed significantly better survival than in nests < stroma cases (MST 388 days vs 256 days; P = .0070). The proportion of tumor-infiltrating macrophages or CD8(+) T cells between cancer nests and stroma became independent prognostic factors in the multivariate analysis. Neither the number of mast cells in nests nor in stroma correlated with the clinical outcome.

CONCLUSIONS

Evaluation of the numbers of macrophages and CD8(+) T cells in cancer nests and stroma are useful biomarkers for predicting the prognosis of stage IV NSCLC patients treated with chemotherapy, but could fail to predict chemotherapy response.

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.

Vandetanib in patients with previously treated RET-rearranged advanced non-small-cell lung cancer (LURET): an open-label, multicentre phase 2 trial

BACKGROUND

RET rearrangements are rare oncogenic alterations in non-small-cell lung cancer (NSCLC). Vandetanib is a multitargeted tyrosine kinase inhibitor exhibiting RET kinase activity. We aimed to assess the efficacy and safety of vandetanib in patients with advanced RET-rearranged NSCLC.

METHODS

In this open-label, multicentre, phase 2 trial (LURET), patients with advanced RET-rearranged NSCLC continuously received 300 mg of oral vandetanib daily. RET-positive patients were screened using a nationwide genomic screening network of about 200 participating institutions. Primary endpoint was the independently assessed objective response in eligible patients. This study is registered with UMIN-CTR, number UMIN000010095.

FINDINGS

Between Feb 7, 2013, and March 19, 2015, 1536 patients with EGFR mutation-negative NSCLC were screened, of whom 34 were RET-positive (2%) and 19 were enrolled. Among 17 eligible patients included in primary analysis, nine (53% [95% CI 28-77]) achieved an objective response, which met the primary endpoint. In the intention-to-treat population of all 19 patients treated with vandetanib, nine (47% [95% CI 24-71]) achieved an objective response. At the data cutoff, median progression-free survival was 4·7 months (95% CI 2·8-8·5). The most common grade 3 or 4 adverse events were hypertension (11 [58%]), diarrhoea (two [11%]), rash (three [16%]), dry skin (one [5%]), and QT prolongation (two [11%]).

INTERPRETATION

Vandetanib showed clinical antitumour activity and a manageable safety profile in patients with advanced RET-rearranged NSCLC. Our results define RET rearrangement as a new molecular subgroup of NSCLC suitable for targeted therapy.

FUNDING

The Ministry of Health, Labour and Welfare of Japan and the Practical Research for Innovation Cancer Control from the Japan Agency for Medical Research and Development, AMED.

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-1alpha (CCL3), RANTES (CCL5), colony-stimulating factor 1, tumor necrosis factor alpha, 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.

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.

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 T(1-2)N(0)M(0) 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 gamma2, E-cadherin, and beta-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.

Blockade of EGFR improves responsiveness to PD-1 blockade in EGFR-mutated non-small cell lung cancer

The clinical efficacy of anti-PD-1 (programmed cell death-1) monoclonal antibody (mAb) against cancers with oncogenic driver gene mutations, which often harbor a low tumor mutation burden, is variable, suggesting different contributions of each driver mutation to immune responses. Here, we investigated the immunological phenotypes in the tumor microenvironment (TME) of epidermal growth factor receptor (EGFR)-mutated lung adenocarcinomas, for which anti-PD-1 mAb is largely ineffective. Whereas EGFR-mutated lung adenocarcinomas had a noninflamed TME, CD4⁺ effector regulatory T cells, which are generally present in the inflamed TME, showed high infiltration. The EGFR signal activated cJun/cJun N-terminal kinase and reduced interferon regulatory factor-1; the former increased CCL22, which recruits CD4⁺ regulatory T cells, and the latter decreased CXCL10 and CCL5, which induce CD8⁺ T cell infiltration. The EGFR inhibitor erlotinib decreased CD4⁺ effector regulatory T cells infiltration in the TME and in combination with anti-PD-1 mAb showed better antitumor effects than either treatment alone. Our results suggest that EGFR inhibitors when used in conjunction with anti-PD-1 mAb could increase the efficacy of immunotherapy in lung adenocarcinomas.

Visceral pleural invasion is an invasive and aggressive indicator of non-small cell lung cancer

OBJECTIVE

Although visceral pleural invasion by non-small cell lung cancer is considered a poor-prognostic factor, further information is lacking, especially in relation to other clinicopathologic prognostic factors. We assessed the relationship between visceral pleural invasion and other clinicopathologic characteristics and evaluated its significance as a prognostic factor.

METHODS

We reviewed 1074 patients with surgically resected T1/2 non-small cell lung cancer for their clinicopathologic characteristics and prognoses. The patients were divided into 2 groups according to visceral pleural invasion status (visceral pleural invasion group and non-visceral pleural invasion group). Both groups were compared with regard to age, sex, histology, tumor size, tumor differentiation, lymph node involvement, lymphatic invasion, vascular invasion, scar grade, nuclear atypia, mitotic index, serum carcinoembryonic antigen level, and survival. Univariate and multivariate analyses were conducted.

RESULTS

Visceral pleural invasion was identified in 288 (26.8%) of the resected specimens. Survival was 76.0% at 5 years and 53.2% at 10 years in the non-visceral pleural invasion group and was 49.8% at 5 years and 37.0% at 10 years in the visceral pleural invasion group. The difference between groups was highly significant ( P < .0001). Visceral pleural invasion was also significantly associated with a higher frequency of lymph node involvement. However, regardless of N status (N0 or N1/2), there was a significant difference in survival when the visceral pleura was invaded. Visceral pleural invasion was observed significantly more frequently in tumors with factors indicative of tumor aggressiveness/invasiveness: moderate/poor differentiation, lymphatic invasion, vascular invasion, high scar grade, high nuclear atypia grade, high mitotic index, and high serum carcinoembryonic antigen level. By multivariate analysis, visceral pleural invasion proved to be a significant independent predictor of poor prognosis in non-small-cell lung cancer patients with or without lymph node involvement.

CONCLUSIONS

Visceral pleural invasion is a significant poor-prognostic factor, regardless of N status. Our analyses indicated that visceral pleural invasion is an independent indicator of non-small cell lung cancer invasiveness and aggressiveness.

Signaling through the Phosphatidylinositol 3-Kinase (PI3K)/Mammalian Target of Rapamycin (mTOR) Axis Is Responsible for Aerobic Glycolysis mediated by Glucose Transporter in Epidermal Growth Factor Receptor (EGFR)-mutated Lung Adenocarcinoma

Oncogenic epidermal growth factor receptor (EGFR) signaling plays an important role in regulating global metabolic pathways, including aerobic glycolysis, the pentose phosphate pathway (PPP), and pyrimidine biosynthesis. However, the molecular mechanism by which EGFR signaling regulates cancer cell metabolism is still unclear. To elucidate how EGFR signaling is linked to metabolic activity, we investigated the involvement of the RAS/MEK/ERK and PI3K/AKT/mammalian target of rapamycin (mTOR) pathways on metabolic alteration in lung adenocarcinoma (LAD) cell lines with activating EGFR mutations. Although MEK inhibition did not alter lactate production and the extracellular acidification rate, PI3K/mTOR inhibitors significantly suppressed glycolysis in EGFR-mutant LAD cells. Moreover, a comprehensive metabolomics analysis revealed that the levels of glucose 6-phosphate and 6-phosphogluconate as early metabolites in glycolysis and PPP were decreased after inhibition of the PI3K/AKT/mTOR pathway, suggesting a link between PI3K signaling and the proper function of glucose transporters or hexokinases in glycolysis. Indeed, PI3K/mTOR inhibition effectively suppressed membrane localization of facilitative glucose transporter 1 (GLUT1), which, instead, accumulated in the cytoplasm. Finally, aerobic glycolysis and cell proliferation were down-regulated when GLUT1 gene expression was suppressed by RNAi. Taken together, these results suggest that PI3K/AKT/mTOR signaling is indispensable for the regulation of aerobic glycolysis in EGFR-mutated LAD cells.

Podoplanin-positive fibroblasts enhance lung adenocarcinoma tumor formation: podoplanin in fibroblast functions for tumor progression

During the metastatic process, cancer cells interact with vascular adventitial fibroblasts (VAF), which are the main components of the outermost connective tissue layer of blood vessels. This activity suggests the presence of a specific tumor microenvironment in the perivascular area. The s.c. coinjection of human lung adenocarcinoma cell lines (A549, PC-14, and CRL-5807) and human VAF (hVAF) resulted in a high rate of tumor formation, compared with the coinjection of these cell lines and human lung tissue-derived fibroblasts (hLF). A cDNA microarray analysis revealed a higher expression level of podoplanin in hVAFs than in hLFs (4.7-fold). Flow cytometry analysis also showed a higher expression level of podoplanin in hVAFs (43% ± 17.5%) than in hLFs (16% ± 10.3%). Sorted podoplanin-positive hVAFs displayed enhanced tumor formation, lymph node metastasis, and lung metastasis of A549 compared to sorted podoplanin-negative hVAFs. Knockdown of podoplanin in hVAFs decreased the augmenting effect of tumor formation and in vitro colony formation. The overexpression of podoplanin in hVAFs hastened the tumor formation of A549, compared with control hVAFs. Furthermore, the analysis of small-sized human lung adenocarcinoma (n = 112) revealed that patients with podoplanin-positive cancer-associated fibroblasts had a significantly higher rate of lymph node metastasis and a high risk of recurrence. These results indicate a promotive effect of hVAFs mediated by podoplanin on cancer progression and suggest that the perivascular environment may constitute a specific niche for tumor progression.

Genomic Profiling of Large-Cell Neuroendocrine Carcinoma of the Lung

PURPOSE

Although large-cell neuroendocrine carcinoma (LCNEC) of the lung shares many clinical characteristics with small-cell lung cancer (SCLC), little is known about its molecular features. We analyzed lung LCNECs to identify biologically relevant genomic alterations.

EXPERIMENTAL DESIGN

We performed targeted capture sequencing of all the coding exons of 244 cancer-related genes on 78 LCNEC samples [65 surgically resected cases, including 10 LCNECs combined with non-small cell lung cancer (NSCLC) types analyzed separately, and biopsies of 13 advanced cases]. Frequencies of genetic alterations were compared with those of 141 SCLCs (50 surgically resected cases and biopsies of 91 advanced cases).

RESULTS

We found a relatively high prevalence of inactivating mutations in TP53 (71%) and RB1 (26%), but the mutation frequency in RB1 was lower than that in SCLCs (40%, P = 0.039). In addition, genetic alterations in the PI3K/AKT/mTOR pathway were detected in 12 (15%) of the tumors: PIK3CA 3%, PTEN 4%, AKT2 4%, RICTOR 5%, and mTOR 1%. Other activating alterations were detected in KRAS (6%), FGFR1 (5%), KIT (4%), ERBB2 (4%), HRAS (1%), and EGFR (1%). Five of 10 cases of LCNECs combined with NSCLCs harbored previously reported driver gene alterations, all of which were shared between the two components. The median concordance rate of candidate somatic mutations between the two components was 71% (range, 60%-100%).

CONCLUSIONS

LCNECs have a similar genomic profile to SCLC, including promising therapeutic targets, such as the PI3K/AKT/mTOR pathway and other gene alterations. Sequencing-based molecular profiling is warranted in LCNEC for targeted therapies. Clin Cancer Res; 23(3); 757-65. ©2016 AACR.

Podoplanin: An emerging cancer biomarker and therapeutic target

Podoplanin (PDPN) is a transmembrane receptor glycoprotein that is upregulated on transformed cells, cancer associated fibroblasts and inflammatory macrophages that contribute to cancer progression. In particular, PDPN increases tumor cell clonal capacity, epithelial mesenchymal transition, migration, invasion, metastasis and inflammation. Antibodies, CAR-T cells, biologics and synthetic compounds that target PDPN can inhibit cancer progression and septic inflammation in preclinical models. This review describes recent advances in how PDPN may be used as a biomarker and therapeutic target for many types of cancer, including glioma, squamous cell carcinoma, mesothelioma and melanoma.

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.

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 alpha-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.

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 K(144)-I(145) peptide bond and one at the R(95)-L(96) 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.

Podoplanin-expressing cancer-associated fibroblasts lead and enhance the local invasion of cancer cells in lung adenocarcinoma

Cancer-associated fibroblasts (CAFs) communicate with cancer cells and play important roles in cancer invasion. We previously reported that local invasion of cancer cells was frequently observed in lung adenocarcinoma patients with podoplanin (PDPN)-expressing CAFs. However, the underlying mechanisms of this phenomenon have remained unclear. In this study, we established a novel collagen invasion assay model in which cancer cells and CAFs were cocultured; we analyzed the mechanisms governing how cancer cell invasion was promoted by PDPN(+)CAFs. By observing the dynamic movement of both CAFs and cancer cells in the collagen matrix, we found that PDPN(+)CAFs invaded the matrix to a greater extent, with more cancer cells invading within the "tracks" created by the CAFs, compared with control CAFs. The knockdown of PDPN in CAFs decreased the invasion of both the CAFs and the cancer cells. PDPN(+)CAFs displayed a higher RhoA activity and treatment with a ROCK inhibitor cancelled the increased invasion ability of PDPN(+)CAFs and subsequently decreased the number of invaded cancer cells. After intravenous injection in the mouse tail vein, PDPN(+)CAFs invaded and promoted cancer cell invasion into the lung parenchyma, compared with control CAFs. Among the patients with lung adenocarcinoma, we observed some cases with PDPN(+)CAFs at the invasive front of the tumor. These cases predominantly exhibited pleural invasion of cancer cells, known as pathological invasiveness. Our results indicated that PDPN(+)CAFs were tumor-promoting CAFs that lead and enhance the local invasion of cancer cells, suggesting that the invasion activity of CAFs themselves could be rate-determining for cancer cell invasion.

Podoplanin, a novel marker of tumor-initiating cells in human squamous cell carcinoma A431

Squamous cell carcinoma (SCC) is a malignant tumor that shows morphologic and phenotypic similarities to normally differentiated squamous epithelium. Thus, it may be an ideal model for seeking a marker of tumor-initiating cells (TICs) based on their morphology. Using the human SCC cell line A431, we found that, as a paradigm of cancer stem cells: (1) podoplanin(+) cells generate both podoplanin(+) and podoplanin(-) cells; (2) podoplanin(-) cells rarely generate podoplanin(+) cells; (3) podoplanin(+) cells have higher colony formation efficiency and tumorigenicity than podoplanin(-) cells; (4) localization and morphology of podoplanin(+) cells in a xenografted tumor derived from podoplanin(+) cells are similar with those in human oral SCC tissue or normal epithelium. Furthermore, podoplanin(+) A431 cells share sonic hedgehog and CD44 expression with stem cells in normal squamous epithelium. Hence, we concluded that podoplanin is a novel marker to enrich TICs with stem-cell-like properties from SCC cell line A431.

Interleukin-11 as a stimulatory factor for bone formation prevents bone loss with advancing age in mice

Cytokines in interleukin (IL)-11 subfamily participate in the regulation of bone cell proliferation and differentiation. We report here positive effects of IL-11 on osteoblasts and bone formation. Overexpression of human IL-11 gene in transgenic mice resulted in the stimulation of bone formation to increase cortical thickness and strength of long bones, and in the prevention of cortical bone loss with advancing age. Bone resorption and osteoclastogenesis were not affected in IL-11 transgenic mice. In experiments in vitro, IL-11 stimulated transcription of the target gene for bone morphogenetic protein (BMP) via STAT3, leading to osteoblastic differentiation in the presence of BMP-2, but inhibited adipogenesis in bone marrow stromal cells. These results indicate that IL-11 is a stimulatory factor for osteoblastogenesis and bone formation to conserve cortical bone, possibly by enhancing BMP actions in bone. IL-11 may be a new therapeutic target for senile osteoporosis.

Immunohistochemical detection of CD133 expression in colorectal cancer: a clinicopathological study

CD133 has been reported to be a cancer-initiating cell marker in colorectal carcinoma. The objective of this study was to evaluate the frequency of CD133 expression in colorectal cancer, the distribution of CD133-positive cancer cells, and their relationship to clinicopathological features, including survival. An immunohistochemical examination of CD133 expression and a clinicopathological analysis were performed in the 189 consecutive colorectal cancer patients. CD133 expression was seen at the luminal surface of cancer glands mainly with cribriform features. Expression was detected in only 29 of the 189 tumors (15.3%). Of these, 21 tumors (11.1%) showed CD133 overexpression. All 21 tumors with CD133 overexpression were diagnosed as well- or moderately-differentiated adenocarcinoma. There was no difference in the distribution of CD133 expressing cells between the invasive area and surface area. Although there was no difference in recurrence-free survival between patients with CD133 overexpression and without, the patients with CD133 overexpression had significantly poorer overall survival (P = 0.03). CD133 overexpression is a risk factor for poorer overall survival in patients with well- and moderately-differentiated adenocarcinoma. Expression of this cancer-initiating cell marker may vary with the histological type of the cancer, and further investigation of the relationship between its expression and clinicopathological features may be necessary.

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.

Pitfalls in lymph node staging with positron emission tomography in non-small cell lung cancer patients

BACKGROUND

The evidence of clinical value of positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) in lymph node (LN) staging in non-small cell lung cancer (NSCLC) has been shown in numerous papers. However, few studies have assessed its limitations. The aim of the present study is to clarify clinico-pathologic factors responsible for false PET results.

METHODS

From July 2000 through December 2001, 71 NSCLC patients underwent both FDG PET and surgical intervention at the National Cancer Center Hospital East, Chiba. Clinical records, computed tomographic (CT) scan findings, PET findings, and histologic findings were retrospectively reviewed.

RESULTS

Sensitivity, specificity, accuracy in nodal staging for CT were 29, 83, and 65% and for PET were 39, 79, and 66%, respectively. There were 10 (14%) false-positive PET scans and 14 (20%) false-negative PET scans. The causative factors for false-positive PET scan were: (1) inflammatory conditions in seven patients; (2) PET mis-localization of an interlobar LN as a mediastinal LN in one patient; (3) inability to distinguish the endobronchial polypoid growth of a primary tumor from a lobar LN in one patient; (4) unknown in one patient. All false-positive LNs due to inflammatory conditions showed reactive lymphoid hyperplasia histologically. The causative factors for false-negative PET scan were: (1) limitation of spatial resolution of the PET scanner in 12 patients (maximum tumor focus dimensions in false-negative LNs ranging from 1 to 7.5 mm, with an average of 3.4 mm); (2) PET mis-localization of a mediastinal LN as a hilar LN in one patient; (3) weak FDG uptake by microscopic tumor foci due to necrosis with massive bleeding in a metastatic LN in one patient.

CONCLUSIONS

Inflammatory conditions were most responsible for false-positive PET scans, and spatial resolution limitation of FDG PET was the causative factor of false-negative PET scans. Recognizing these factors in advance would be clinically helpful in accurate nodal staging with FDG PET.