Clinical significance of macrophage heterogeneity in human malignant tumors with articles on down-regulating VEGF

It has long been known that many leukocytes including macrophages are present in tumor tissues and that these cells, together with fibroblasts and vascular endothelial cells, form the tumor microenvironment.[1-4] Previously, activated macrophages were believed to exhibit antitumor activity by directly attacking tumor cells in the tumor microenvironment.[5] However, many recent studies have indicated the protumoral functions of tumor-associated macrophages (TAMs), and thus, TAMs are believed to directly or indirectly promote tumor progression.[6-8] Great advances have been made in TAM research over the past dozen years or so, with one of the most significant breakthroughs being the development of immunohistochemical methods for identifying TAMs in tumor tissue. Numerous studies using human samples have been carried out using CD68 as a macrophage marker, whereas CD163 and CD204 have been used as markers of M2 macrophages in recent studies.[9, 10] Although variability is observed according to tumor tissue type and location, over 80% of immunohistochemical studies using various human tumor tissues have shown that higher numbers of TAMs are associated with worse clinical prognosis.[9] Supporting these clinical observations, in vitro experiments using human tumor cells and experiments using animal models indicate that TAMs promote tumor cell growth by suppressing antitumor immunity and inducing angiogenesis.[11, 12]

TAMs promote tumor progression through induction of angiogenesis and suppression of antitumor immunity. In particular, in humans, protumoral TAMs are believed to exhibit characteristics similar to M2 macrophages, and are intimately involved in the progression of malignant tumors. As such, treatment strategies aimed at local inhibition of macrophage differentiation into the M2 phenotype are anticipated to be effective. Signal transduction pathways, including nuclear factor (NF)-?B, Stat3, Stat6, c-Myc, and interferon regulatory factor 4, are involved in differentiation into the M2 phenotype.[13, 14-16] Nuclear factor-?B and Stat3 are also strongly involved in tumor cell growth, and drugs targeting these molecules are currently being developed. Among such molecule-specific drugs, synergistic efficacy due to direct effects on tumor cells, as well as inhibition of the differentiation of TAMs into the M2 phenotype, is expected. Among drugs currently in use, some are active against TAMs. Cyclosporin A and trabectedin not only directly inhibit tumor cell growth, they also suppress activation of TAMs.[17] Bisphosphonates not only suppress bone resorption by osteoclasts, they also inhibit the differentiation of TAMs into the M2 phenotype. The angiogenic inhibitor bevacizumab (a VEGF-inhibiting antibody) has recently been used to treat solid tumors such as colorectal adenocarcinoma, and this drug also exhibits antitumor activity by suppressing TAM migration.[18]

Source

Komohara Y et al. Cancer Science. Volume 105, Issue 1, pages 1–8, January 2014. DOI: 10.1111/cas.12314

References

1. Monis B, Weinberg T. Cytochemical study of esterase activity of human neoplasms and stromal macrophages. Cancer 1961; 14: 369–77.

2. Underwood JC, Carr I. The ultrastructure of the lymphoreticular cells in non-lymphoid human neoplasms. Virchows Arch B Cell Pathol 1972; 12: 39–50.

3. Lauder I, Aherne W, Stewart J, Sainsbury R. Macrophage infiltration of breast tumours: a prospective study. J Clin Pathol 1977; 30: 563–8.

4. Kreutz M, Fritsche J, Andreesen R. Macrophages in tumor biology. In; Burke B, Lewis CE, eds. The Macrophage, 2nd edn. Oxford, UK: Oxford Univ. Press, 2002; 458–89.

5. Tagliabue A, Mantovani A, Kilgallen M, Herberman RB, McCoy JL. Natural cytotoxicity of mouse monocytes and macrophages. J Immunol 1979; 122: 2363–70.

6. Mantovani A, Sozzani S, Locati M, Allavena P, Sica A. Macrophage polarization: tumor-associated macrophages as a paradigm for polarized M2 mononuclear phagocytes. Trends Immunol 2002; 23: 549–55.

7. Bingle L, Brown NJ, Lewis CE. The role of tumour-associated macrophages in tumour progression: implications for new anticancer therapies. J Pathol 2002; 196: 254–65.

8. Pollard JW. Tumour-educated macrophages promote tumour progression and metastasis. Nat Rev Cancer 2004; 4: 71–8.

9. Heusinkveld M, van der Burg SH. Identification and manipulation of tumor associated macrophages in human cancers. J Transl Med 2011; 9: 216.

10. Komohara Y, Ohnishi K, Kuratsu J, Takeya M. Possible involvement of the M2 anti-inflammatory macrophage phenotype in growth of human gliomas. J Pathol 2008; 216: 15–24.

11. Sica A, Schioppa T, Mantovani A, Allavena P. Tumour-associated macrophages are a distinct M2 polarised population promoting tumour progression: potential targets of anti-cancer therapy. Eur J Cancer 2006; 42: 717–27.

12. Yu H, Kortylewski M, Pardoll D. Crosstalk between cancer and immune cells: role of STAT3 in the tumour microenvironment. Nat Rev Immunol 2007; 7: 41–51.

13. Sica A, Mantovani A. Macrophage plasticity and polarization: in vivo veritas. J Clin Invest 2012; 122: 787–95.

14. Pello OM, De Pizzol M, Mirolo M et al. Role of c-MYC in alternative activation of human macrophages and tumor-associated macrophage biology. Blood 2012; 119: 411–21.

15. Satoh T, Takeuchi O, Vandenbon A et al. The Jmjd3-Irf4 axis regulates M2 macrophage polarization and host responses against helminth infection. Nat Immunol 2010; 11: 936–44.

16. Lawrence T, Natoli G. Transcriptional regulation of macrophage polarization: enabling diversity with identity. Nat Rev Immunol 2011; 11: 750–61.

17. Germano G, Frapolli R, Belgiovine C et al. Role of macrophage targeting in the antitumor activity of trabectedin. Cancer Cell 2013; 23: 249–62.

18. Roland CL, Dineen SP, Lynn KD et al. Inhibition of vascular endothelial growth factor reduces angiogenesis and modulates immune cell infiltration of orthotopic breast cancer xenografts. Mol Cancer Ther 2009; 8: 1761–71.

HERBS AND COMPOUND, WHICH INHIBIT/DOWNREGULATE VEGF

Vascular abnormalities inside tumors are important factors resulting in abnormal tumor microenvironment. Microenvironment was closely correlated with the malignant degrees, metastasis, and recurrence of tumors. Besides, the acid environment, oxygen deficiency, and other factors it induced may severely affect the efficacies of routine therapies, radiotherapy and chemotherapy. Anti-angiogenesis treatment drugs targeting vascular endothelial growth factor (VEGF) not only antagonize the angiogenesis of tumor vessels, but also promote the vascular normalization inside tumors to some extent, thus reducing interstitial hypertension, improving blood flow inside tumors, and enhancing therapeutic efficacies. Previous clinical and experimental studies have proved that many Chinese herbs show enhancing effects of chemotherapy and radiotherapy in comprehensive treatment of chemotherapy and radiotherapy combination. Meanwhile, recent studies have also proved that many Chinese herbs could fight against tumor vascular angiogenesis, lower serum VEGF concentration, and inhibit expressions of VEGF. Therefore, studying Chinese herbs’ mechanisms of anti-tumor from promoting vascular normalization will open up a brand new field for seeking a cut-in point for Chinese medicine therapy in the comprehensive treatment, optimizing a treatment protocols, and further clarifying the roles of Chinese medicine in the comprehensive treatment.Source

Source

You J. Study on the tumor microenvironment and tumor vascular normalization in integrative treatment of tumor by Chinese medicine and western medicine. Zhongguo Zhong Xi Yi Jie He Za Zhi. 2011 Aug;31(8):1127-31.

Medicinal herbs and their phytochemicals are potential novel leads for developing antiangiogenic drugs. This review aims to assess the current status of research with medicinal herbs and their phytochemicals for the development of antiangiogenic agents for cancer and other angiogenesis-related diseases including inflammation, diabetic retinopathy, endometriosis and obesity. Most studies reviewed have focused on vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor 2 (VEGFR-2) signaling for endothelial response processes and have led to the identification of many potential antiangiogenic agents. Since human clinical trials with antiangiogenic modalities targeting VEGF/VEGFR-2 signaling have shown limited efficacy and occasional toxic side effects, screening strategies for herbal phytochemicals based on other signaling pathways important for cancer-endothelial and stromal crosstalks should be emphasized in the future.

Source

Jeong SJ, Koh W, Lee EO, Lee HJ, Lee HJ, Bae H, Lü J, Kim SH. Antiangiogenic phytochemicals and medicinal herbs. Phytother Res. 2011 Jan;25(1):1-10. doi: 10.1002/ptr.3224. DOI: 10.1002/ptr.3224

The Relationship between tumor blood flow, angiogenesis, tumor hypoxia, and aerobic glycolysis

Anaerobic glycolysis is the transformation of glucose to pyruvate when limited amounts of oxygen (O2) are available. persistent metabolism of glucose to lactate even in aerobic conditions is an adaptation to intermittent hypoxia in pre-malignant lesions. However, upregulation of glycolysis leads to microenvironmental acidosis requiring evolution to phenotypes resistant to acid-induced cell toxicity.

The survival of cancer cells is contingent on their supply of oxygen and nutrients such as glucose via the bloodstream. The establishment and growth of malignant tumors are, therefore, critically dependent on their ability to stimulate the formation of new blood vessels (angiogenesis) to support their metabolic needs

Antiangiogenic therapies are being pursued as a means of starving tumors of their energy supply. Although numerous studies show that such therapies render tumors hypoxic, just as many studies have, surprisingly, shown improved tumor oxygenation. These contradicting findings challenge both the original rationale for antiangiogenic therapy and our understanding of the physiology of tissue oxygenation. The flow–diffusion equation, which describes the relation between blood flow and the extraction of freely diffusible molecules in tissue, was recently extended to take the heterogeneity of capillary transit times (CTH) into account. CTH is likely to be high in the chaotic microvasculature of a tumor, increasing the effective shunting of blood through its capillary bed. We review the properties of the extended flow–diffusion equation in tumor tissue. Elevated CTH reduces the extraction of oxygen, glucose, and cytotoxic molecules. The extent to which their net extraction is improved by antiangiogenic therapy, in turn, depends on the extent to which CTH is normalized by the treatment. The extraction of oxygen and glucose are affected to different extents by elevated CTH, and the degree of aerobic glycolysis—known as the Warburg effect—is thus predicted to represent an adaptation to the CTH of the local microvasculature.

Source

Østergaard L, Tietze A, Nielsen T, et al. Cancer Res September 15, 2013 73; 5618. doi: 10.1158/0008-5472.CAN-13-0964

Genistein from soy inhibits tumor invasion by suppressing multiple signal transduction pathways in human hepatocellular carcinoma cells

Genistein (Gen) exhibits anti-mutagenic and anti-metastatic activities in hepatoma cell lines. Gen has suppressive effects on tumor growth and angiogenesis in nude mice. Gen suppresses the enzymatic activity of matrix metalloproteinase (MMP)-9; however, the mechanism underlying its anti-invasive activity on hepatocellular carcinoma (HCC) cells is unclear.

In this study, the possible mechanisms underlying Gen-mediated reduction of 12-O-Tetradecanoylphorbol-13-acetate (TPA)-induced cell invasion and inhibition of secreted and cytosolic MMP-9 production in human hepatoma cells (HepG2, Huh-7, and HA22T) and murine embryonic liver cells (BNL CL2) were investigated.
Gen suppressed MMP-9 transcription by inhibiting activator protein (AP)-1 and nuclear factor-kappa B (NF-kappaB) activity. Gen suppressed TPA-induced AP-1 activity through inhibitory phosphorylation of extracellular signal-related kinase (ERK) and c-Jun N-terminal kinase (JNK) signaling pathways, and TPA-stimulated inhibition of NF-kappaB nuclear translocation through IkappaB inhibitory signaling pathways. Moreover, Gen suppressed TPA-induced activation of ERK/phosphatidylinositol 3-kinase/Akt upstream of NF-kappaB and AP-1.

Gen and its inhibition of multiple signal transduction pathways can control the invasiveness and metastatic potential of HCC. 
Source

Inhibitory and cytotoxic activities of salvia officinalis L. Extract on human lymphoma and leukemia cells by induction of apoptosis.

Salvia officinalis L., also known as Maryam Goli, is one of the native plants used to Persian medicinal herbs. Zare Shahneh et al., (2013) examined the in vitro cytotoxic activities of a standardized crude methanol extracts prepared from Salvia officinalis L., on a non-Hodgkin’s B-cell lymphoma (Raji) and human leukemic monocyte lymphoma (U937), Human acute myelocytic leukemia (KG-1A) and Human Umbilical Vein Endothelial (HUVEC) cell lines. 

The effect of methanolic extract on the inhibition of cell proliferation and cytotoxic activity was evaluated by Dye exclusion and Micro culture tetrazolium test (MTT) cytotoxicity assay. Cell death ELISA was employed to quantify the nucleosome production result from nuclear DNA fragmentation during apoptosis and determined whether the mechanism involves induction of apoptosis or necrosis. 

The present results demonstrated that methanolic extract at 50 to 800 ?g/ml dose and time-dependently suppressed the proliferation of KG-1A, U937 and Raji cells by more than 80% (p<0.01), with ascending order of IC50 values in 24: KG-1A (214.377 ?g/ml), U937 (229.312 ?g/ml) and Raji (239.692 ?g/ml) when compared with a chemotherapeutic anticancer drug, paclitaxel (Toxol), confirming the tumour-selective cytotoxicity. The crude extract however did not exert any significant cytotoxic effect on normal cell line HUVEC (IC50>800 Ag/ml). Nucleosome productions in KG-1A, Raji and U937 cells were significantly increased respectively upon the treatment of Salvia officinalis L. extract. 

The Salvia officinalis L. extract was found dose and time-dependently inhibits the proliferation of lymphoma and leukemic cells possibly via an apoptosis-dependent pathway. 

Source
Zare Shahneh F, Valiyari S, Baradaran B, et al. (2013) Adv Pharm Bull. 2013;3(1):51-5. doi: 10.5681/apb.2013.009. 

Ursolic acid inhibits the growth of colon cancer-initiating cells by targeting STAT3.

Wong et al., have previously reported Signal Transducer and Activator of Transcription 3 (STAT3) to be constitutively activated in aldehyde dehydrogenase (ALDH)(+)/cluster of differentiation-133 (CD133)(+) colon cancer-initiating cells. In the present study they tested the efficacy of inhibiting STAT3 signaling in human colon cancer-initiating cells by ursolic acid (UA), which exists widely in fruits and herbs.

Their data demonstrated that UA inhibited STAT3 phosphorylation, and induced caspase-3 cleavage of ALDH(+)/CD133(+) colon cancer-initiating cells. UA also reduced cell viability and inhibited tumor sphere formation of colon cancer-initiating cells, more potently than two other natural compounds, resveratrol and capsaicin. UA also inhibited the activation of STAT3 induced by interleukin-6 in DLD-1 colon cancer cells. Furthermore, daily administration of UA suppressed HCT116 tumor growth in mice in vivo.

Their results suggest STAT3 to be a target for colon cancer prevention. UA, a dietary agent, might offer an effective approach for colorectal carcinoma prevention by inhibiting persistently activated STAT3 in cancer stem cells.

Source Wang W, Zhao C, Jou D, Lü J, Zhang C, Lin L, Lin J. Anticancer Res. 2013 Oct;33(10):4279-84.