Redistribution of fibroblasts and macrophages as micrometastases develop into established liver metastases

Limited fibrosis accompanies triple-negative breast cancer metastasis in multiple model systems and is not a preventive target

The lysophosphatidic acid receptor 1 (LPAR1) is mechanistically implicated in both tumor metastasis and tissue fibrosis. Previously, metastasis was increased when fulminant fibrosis was first induced in mice, suggesting a direct connection between these processes. The current report examined the extent of metastasis-induced fibrosis in breast cancer model systems, and tested the metastasis preventive efficacy and fibrosis attenuation of antagonists for LPAR1 and Idiopathic Pulmonary Fibrosis (IPF) in breast and ovarian cancer models. Staining analysis demonstrated only focal, low-moderate levels of fibrosis in lungs from eleven metastasis model systems. Two orally available LPAR1 antagonists, SAR100842 and EPGN9878, significantly inhibited breast cancer motility to LPA in vitro. Both compounds were negative for metastasis prevention and failed to reduce fibrosis in the experimental MDA-MB-231T and spontaneous murine 4T1 in vivo breast cancer metastasis models. SAR100842 demonstrated only occasional reductions in invasive metastases in the SKOV3 and OVCAR5 ovarian cancer experimental metastasis models. Two approved drugs for IPF, nintedanib and pirfenidone, were investigated. Both were ineffective at preventing MDA-MB-231T metastasis, with no attenuation of fibrosis. In summary, metastasis-induced fibrosis is only a minor component of metastasis in untreated progressive breast cancer. LPAR1 antagonists, despite in vitro evidence of specificity and efficacy, were ineffective in vivo as oral agents, as were approved IPF drugs. The data argue against LPAR1 and fibrosis as monotherapy targets for metastasis prevention in triple-negative breast cancer and ovarian cancer.

Angiotensin II subtype 1a receptor signaling in resident hepatic macrophages induces liver metastasis formation

Liver metastases from colorectal cancer (CRC) are a clinically significant problem. The renin-angiotensin system is involved in tumor growth and metastases. This study was designed to evaluate the role of angiotensin II subtype receptor 1a (AT1a) in the formation of liver metastasis in CRC. A model of liver metastasis was developed by intrasplenic injection of mouse colon cancer (CMT-93) into AT1a knockout mice (AT1aKO) and wild-type (C57BL/6) mice (WT). Compared with WT mice, the liver weight and liver metastatic rate were significantly lower in AT1aKO. The mRNA levels of CD31, transforming growth factor- β1 (TGF-β1), and F4/80 were suppressed in AT1aKO compared with WT. Double immunofluorescence analysis showed that the number of accumulated F4/80+ cells expressing TGF-β1 in metastatic areas was higher in WT than in AT1aKO. The AT1aKO bone marrow (BM) (AT1aKO-BM)→WT showed suppressed formation of liver metastasis compared with WT-BM→WT. However, the formation of metastasis was further suppressed in WT-BM→AT1aKO compared with AT1aKO-BM→WT. In addition, accumulated F4/80+ cells in the liver metastasis were not BM-derived F4/80+ cells, but mainly resident hepatic F4/80+ cells, and these resident hepatic F4/80+ cells were positive for TGF-β1. Angiotensin II enhanced TGF-β1 expression in Kupffer cells. Treatment of WT with clodronate liposomes suppressed liver metastasis by diminishing TGF-β1+ F4/80+ cells accumulation. The formation of liver metastasis correlated with collagen deposition in the metastatic area, which was dependent on AT1a signaling. These results suggested that resident hepatic macrophages induced liver metastasis formation by induction of TGF-β1 through AT1a signaling.

Fibrosis and Mast Cells in Colorectal Lesions: Significance in Adenoma-Colorectal Cancer Sequence and Association with Diet

PURPOSE

Adenoma is the most common benign neoplasm with potential to progress into colorectal cancer (CRC), a disease responsible for high rates of mortality. However, it is not possible yet to establish which lesions will evolve into CRC. We aimed to investigate the intrinsic factors, diet profile, and microenvironment as factors involved in adenoma-CRC progression.

METHODS

We evaluated nutritional profile and microscopic features. Adenomas and CRC lesions were stained with Mallory's trichrome to reveal fibrosis and Alcian blue to identify mast cells.

RESULTS

A total of 143 patients was selected, 66 % diagnosed with normal mucosa, 28.4 % with benign lesion, and 5.6 % with CRC. A higher frequency of lesions was associated with patients older than 50 years (26.57 %) and women (18.18 %), but men were more likely to develop CRC. Regarding microscopic aspects, epithelium-connective tissue interface with disorganization feature was significantly higher in CRC when compared to adenoma (P = 0.0007). A greater fibrosis around vessels was also observed in CRC (P = 0.01). The statistical analysis indicated a significant correlation between mast cell population and patients older than 50 years (P < 0.01), male (P < 0.01), with right colon lesion (P < 0.05) and CRC. Low consumption of leafy greens (P < 0.001) and carotenoids (P < 0.01) and elevated consumption of red meat (P < 0.001) were associated with a high density of mast cells.

CONCLUSIONS

An association between clinical, diet profile, and microscopic features in colorectal lesions was observed, with a progressive change in the microenvironment during adenoma-CRC sequence.

Redirecting Transport of Nanoparticle Albumin-Bound Paclitaxel to Macrophages Enhances Therapeutic Efficacy against Liver Metastases

Current treatments for liver metastases arising from primary breast and lung cancers are minimally effective. One reason for this unfavorable outcome is that liver metastases are poorly vascularized, limiting the ability to deliver therapeutics from the systemic circulation to lesions. Seeking to enhance transport of agents into the tumor microenvironment, we designed a system in which nanoparticle albumin-bound paclitaxel (nAb-PTX) is loaded into a nanoporous solid multistage nanovector (MSV) to enable the passage of the drug through the tumor vessel wall and enhance its interaction with liver macrophages. MSV enablement increased nAb-PTX efficacy and survival in mouse models of breast and lung liver metastasis. MSV-nAb-PTX also augmented the accumulation of paclitaxel and MSV in the liver, specifically in macrophages, whereas paclitaxel levels in the blood were unchanged after administering MSV-nAb-PTX or nAb-PTX. In vitro studies demonstrated that macrophages treated with MSV-nAb-PTX remained viable and were able to internalize, retain, and release significantly higher quantities of paclitaxel compared with treatment with nAb-PTX. The cytotoxic potency of the released paclitaxel was also confirmed in tumor cells cultured with the supernatants of macrophage treated with MSV-nAB-PTX. Collectively, our findings showed how redirecting nAb-PTX to liver macrophages within the tumor microenvironment can elicit a greater therapeutic response in patients with metastatic liver cancer, without increasing systemic side effects.

Kupffer cells decrease metastasis of colon cancer cells to the liver in the early stage

Although Kupffer cells (KCs) play an important role in the liver's immune response, their role in colon cancer metastasis to the liver is unclear. We here analyzed the relationship between KCs and tumor cells (TCs) in colon cancer metastasis to the liver. Fischer 344 (F344) rats were divided into control group (KC+ group) and KC elimination group (KC‑ group), in which KC elimination was induced by Cl2MDP liposome injection. RCN‑H4 colon cancer cells were injected into the rats of both groups, and the relationship between the two types of cells was observed by intravital microscopy (IVM) for 6 h. Moreover, to investigate the effect of KCs on liver metastasis formation, KCs were eliminated at different time points before and after the TC injection. The number of metastatic nodules 2 weeks after the injection was evaluated. In the KC‑ group, IVM revealed that the number of adherent TCs had increased 1.5‑fold at 6 h after the TC injection as compared with in the KC+ group. Moreover, in the KC+ group, 74% of the TCs adhered to the KCs, and KC activation and KC phagocytosis of the TCs were observed. Two weeks after the injection, the number of metastatic nodules was significantly increased in rats in which the KCs had been eliminated before the injection, but not in rats in which the KCs had been eliminated after the injection. KC activation and KC phagocytosis of TCs decreased colon cancer cell metastasis to the liver.

Design and development of a robotized system coupled to µCT imaging for intratumoral drug evaluation in a HCC mouse model

Hepatocellular carcinoma (HCC) is one of the most common cancer related deaths worldwide. One of the main challenges in cancer treatment is drug delivery to target cancer cells specifically. Preclinical evaluation of intratumoral drugs in orthotopic liver cancer mouse models is difficult, as percutaneous injection hardly can be precisely performed manually. In the present study we have characterized a hepatoma model developing a single tumor nodule by implantation of Hep55.1C cells in the liver of syngeneic C57BL/6J mice. Tumor evolution was followed up by µCT imaging, and at the histological and molecular levels. This orthotopic, poorly differentiated mouse HCC model expressing fibrosis, inflammation and cancer markers was used to assess the efficacy of drugs. We took advantage of the high precision of a previously developed robotized system for automated, image-guided intratumoral needle insertion, to administer every week in the tumor of the Hep55.1C mouse model. A significant tumor growth inhibition was observed using our robotized system, whereas manual intraperitoneal administration had no effect, by comparison to untreated control mice.

The desmoplastic reaction surrounding hepatic colorectal adenocarcinoma metastases aids tumor growth and survival via alphav integrin ligation

PURPOSE

The treatment of metastatic colorectal carcinoma represents a major clinical challenge. We investigated the hypothesis that the desmoplastic reaction within the liver elicited by metastatic adenocarcinoma, characterized by collagen I deposition and altered collagen IV distribution, promotes the growth and survival of hepatic colorectal carcinoma metastases.

EXPERIMENTAL DESIGN

Partial hepatectomy specimens for metastatic colorectal adenocarcinoma were examined immunohistochemically for differential integrin expression. Human colorectal adenocarcinoma cell lines HT-29, KM12SM, and KM12c were grown on wild-type collagen I or IV, or cleavage-resistant r/r collagen I, and assessed for their growth, survival, and resistance to 5-fluorouracil. The effect of alpha(v)beta(3) and alpha(v)beta(5) integrin blockade by neutralizing antibodies was examined.

RESULTS

Collagen I, in contrast to collagen IV, significantly enhanced the growth, survival, and chemoresistance of colorectal carcinoma cells. Blockade of the alpha(v)beta(3) and alpha(v)beta(5) integrins significantly reduced colorectal carcinoma cell proliferation on collagen, especially in the cell line with the most metastatic potential. These in vitro findings correlated with the pattern of integrin expression identified within resected hepatic colorectal carcinoma metastases. Using matrix metalloproteinase-resistant r/r collagen I as a dominant negative ligand for alpha(v) integrins, we showed a key role for this integrin-ligand interaction in mediating the survival and proliferation of colorectal carcinoma cells.

CONCLUSIONS

Desmoplasia has an important role in the development of hepatic colorectal carcinoma metastasis. The interaction between integrin and collagen I is identified as a potential therapeutic target.

Hepatic colorectal cancer metastases: imaging initial steps of formation in mice

PURPOSE

To prospectively use optical imaging to study the cell-specific mechanisms of entrapment and subsequent growth of two human colon cancer cell lines differing in their propensity to form hepatic metastases.

MATERIALS AND METHODS

In this Animal Care Committee-approved study, intravital optical imaging was performed in exteriorized livers of three groups of mice after intrasplenic inoculation of human colon cancer cells. Group 1 mice (control group; n=12) received a cell-maintaining solution only. Groups 2 and 3 (n=12 in each) were administered poorly (MIP-101 colon cancer cells) or highly (CX-1 colon cancer cells) metastatic cells. Imaging was performed on postinoculation days 0, 1, 3, and 6 to document sites and mechanisms of tumor cell entrapment and presence and sites of endothelial cell activation and of tumor cell interactions with systemic macrophages and Kupffer cells. Fluorescence intensity of Kupffer cells was compared by using the Mann-Whitney test. Immunohistochemistry served as the reference standard for all in vivo observations.

RESULTS

Whereas both MIP-101 and CX-1 colon cancer cells adhered to periportal Kupffer cells, the CX-1 cells resulted in Kupffer cell activation, evidenced in vivo by increased visible peroxidase activity (P<.05). Only CX-1 cells were associated with subsequent downstream endothelial cell activation, evidenced by in vivo expression of E-selectin. By day 6, regression of periportal MIP-101 tumor growth correlated with ingrowth of systemic macrophages, while CX-1 tumor growth, originating in the outflow venous regions, correlated with translobular migration and ingrowth of activated Kupffer cells.

CONCLUSION

Formation of hepatic colon cancer metastases is cancer cell-type specific, with cell lines differing in their mechanisms and intrahepatic locations of initial entrapment and Kupffer cell activation and subsequent growth.

K-19 mRNA RT-PCR in detecting micrometastasis in regional lymph nodes of gastric cancer

AIM: To investigate the value and prospect of RT-PCR in detecting micrometastasis in regional lymph nodes of gastric cancer.

METHODS: Histopathology was used and K19 mRNA expression was detected by RT-PCR in tumor tissues and lymph nodes from gastric cancer patients undergoing radical resection of gastric carcinoma.

RESULTS: K19 mRNA was expressed in all tumor specimens of 30 cases; of the 126 lymph nodes, 26 were histopathologically positive (20.6%), and 42 positive (33.3%) by RT-PCR. Amplification fragments of 460 and 540 bp were shown in all the tumor tissues and metastatic lymph nodes after K19 and β-actin RT-PCR, while only a 540 bp fragment appeared in the lymph nodes of non-tumor patients.

CONCLUSION: K19 mRNA RT-PCR is sensitive and specific in testing micrometastasis in regional lymph nodes of gastric cancer, and it is superior to routine histopathology.

Hepatic local cellular immune status and prognosis of hepatocellular carcinoma

AIM: To investigate the local cellular immune status in the tissues of liver cirrhosis (LC) and hepatocellular carcinoma (HCC) and its relationship with the prognosis of the patients.

METHODS: Surgical specimens from 60 cases of HCC, 62 cases of LC, and 23 normal liver tissues were stained of CD₃, CD₅₇, CD₂₀, CD₆₈ and GrB with streptavidin-horseradish peroxidase detection system to assess the number and the distribution of hepatic local immunocytes.

RESULTS: The numbers of T lymphocytes (60.5±18.9), B lymphocytes (40.3±29.9) and NK cells (6.8±5.1) in the liver of HCC patients were significantly higher than those in the liver of LC patients (53.0±18.7, t = 2.21, P = 0.029<0.05; 21.5±18.2, t = 4.19, P = 0.000<0.01; 4.2±2.9, t = 3.53, P = 0.001<0.01, respectively) and normal controls (45.4±11.7, t = 3.57, P = 0.001<0.01; 8.1±5.9, t = 7.97, P = 0.000<0.01; 4.8±2.3, t = 2.54, P = 0.013<0.05, respectively ); while the number of macrophages (Mf)(24.6±13.4)was significantly lower than that in the liver of LC patients(41.0±13.5, t = 6.74, P = 0.000<0.01)and normal controls (40.3±8.9, t = 6.17, P = 0.000<0.01). The numbers of T and B lymphocytes in the liver of LC patients were significantly higher than those in normal controls (T cells: 53.0±18.7 vs 45.4±11.7, t = 2.23, P = 0.029<0.05; B cells: 21.5±18.2 vs 8.1±5.9, t = 5.14, P = 0.000<0.01). GrB positive cells in the liver mostly consisted of CD₅₇ positive cells and a few CD₃ positive cells. The numbers of NK cells, B lymphocytes and GrB positive cells in the cancerous tissues of stages I and II were significantly higher than that of stages III and IV (8.3±5.3 vs 5.3±4.5, t = 5.38, P = 0.024<0.05; 49.1±29.8 vs31.0±27.5, t = 2.44, P = 0.018<0.05; 6.8±5.3 vs 4.1±3.2, t = 2.32, P = 0.024<0.05, respectively). The numbers of T lymphocytes, NK cells, Mj and GrB positive cells in HCC with metastasis in 15 months were significantly lower than those without metastasis (53.1±16.0 vs 65.5±21.1, t = 2.41, P = 0.02<0.05; 2.9±3.1 vs 9.4±4.5, t = 6.33, P = 0.000<0.01; 20.9±11.3vs 30.1±14.4, t = 2.62, P = 0.012<0.05; 2.5±1.6 vs 7.0±4.3, t = 5.02, P = 0.000<0.01, respectively). The numbers of T lymphocytes, NK cells, B lymphocytes and GrB positive cells decreased gradually with the progressing of disease in the HCC patients.

CONCLUSION: The numbers of T lymphocytes, NK cells, B lymphocytes, Mf and GrB positive cells might be important markers to assess the hepatic local immune status and useful factors to predict the prognosis of HCC patients.

Functional Imaging of Proteolysis: Stromal and Inflammatory Cells Increase Tumor Proteolysis

The underlying basement membrane is degraded during progression of breast and colon carcinoma. Thus, we imaged degradation of a quenched fluorescent derivative of basement membrane type IV collagen (DQ-collagen IV) by living human breast and colon tumor spheroids. Proteolysis of DQ-collagen IV by HCT 116 and HKh-2 human colon tumor spheroids was both intracellular and pericellular. In contrast, proteolysis of DQ-collagen IV by BT20 human breast tumor spheroids was pericellular. As stromal elements can contribute to proteolytic activities associated with tumors, we also examined degradation of DQ-collagen IV by human monocytes/macrophages and colon and breast fibroblasts. Fibroblasts themselves exhibited a modest amount of pericellular degradation. Degradation was increased 4–17-fold in cocultures of fibroblasts and tumor cells as compared to either cell type alone. Inhibitors of matrix metalloproteinases, plasmin, and the cysteine protease, cathepsin B, all reduced degradation in the cocultures. Monocytes did not degrade DQ-collagen IV; however, macrophages degraded DQ-collagen IV intracellularly. In coculture of tumor cells, fibroblasts, and macrophages, degradation of DQ-collagen IV was further increased. Imaging of living tumor and stromal cells has, thus, allowed us to establish that tumor proteolysis occurs pericellularly and intracellularly and that tumor, stromal, and inflammatory cells all contribute to degradative processes.