Adrenomedullin is a therapeutic target in colorectal cancer

Inhibition of the Alternative Complement Pathway May Cause Secretion of Factor B, Enabling an Early Detection of Pancreatic Cancer

This study aims to elucidate the cellular mechanisms behind the secretion of complement factor B (CFB), known for its dual roles as an early biomarker for pancreatic ductal adenocarcinoma (PDAC) and as the initial substrate for the alternative complement pathway (ACP). Using parallel reaction monitoring analysis, we confirmed a consistent ∼2-fold increase in CFB expression in PDAC patients compared with that in both healthy donors (HD) and chronic pancreatitis (CP) patients. Elevated ACP activity was observed in CP and other benign conditions compared with that in HD and PDAC patients, suggesting a functional link between ACP and PDAC. Protein-protein interaction analyses involving key complement proteins and their regulatory factors were conducted using blood samples from PDAC patients and cultured cell lines. Our findings revealed a complex control system governing the ACP and its regulatory factors, including Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation, adrenomedullin (AM), and complement factor H (CFH). Particularly, AM emerged as a crucial player in CFB secretion, activating CFH and promoting its predominant binding to C3b over CFB. Mechanistically, our data suggest that the KRAS mutation stimulates AM expression, enhancing CFH activity in the fluid phase through binding. This heightened AM-CFH interaction conferred greater affinity for C3b over CFB, potentially suppressing the ACP cascade. This sequence of events likely culminated in the preferential release of ductal CFB into plasma during the early stages of PDAC. (Data set ID PXD047043.).

Adrenomedullin induces cisplatin chemoresistance in ovarian cancer through reprogramming of glucose metabolism

Background and Objectives

The metabolic network of cancer cells has been reprogrammed - relying more on aerobic glycolysis to gain energy, which is an important reason for drug resistance. Expression of adrenomedullin (ADM) in ovarian cancer tissues is related to resistance to platinum-based drugs. In view of this, we intended to investigate the correlation between ADM and glucose metabolism reprogramming of tumor cells to clarify the possible mechanism of ADM-induced ovarian cancer cisplatin resistance through glucose metabolism reprogramming.

Methods

Epithelial ovarian cancer (EOC) cell viability and apoptosis were determined. Different gene expression and protein levels were detected by real-time revere transcription polymerase chain reaction and western blotting. Oxygen consumption rate (OCR) and extracellular acidification rates (ECARs) were measured.

Results

ADM expression was upregulated in cisplatin-resistant EOC cells. ADM attenuated cisplatin-inhibited cell survival and cisplatin-induced apoptosis in sensitive EOC cells; knockdown of ADM enhanced cisplatin chemosensitivity of cisplatin-resistant EOC cells. ADM enhanced glycolysis in cisplatin-sensitive EOC cells; knockdown of ADM significantly inhibited glycolysis in cisplatin-resistant EOC cells. ADM significantly upregulated pyruvate kinase isozyme type M2 (PKM2) protein level, the key enzyme during glycolysis; PKM2 inhibitor significantly abolished the ADM-improved cell survival and ADM-inhibited apoptosis.

Conclusion

ADM promoted proliferation and inhibited apoptosis of ovarian cancer cells through reprogramming of glucose metabolism, so as to promote cisplatin resistance. The study is expected to identify multidrug resistance markers of ovarian cancer and provide a target for the prevention and treatment of ovarian cancer, which is important for clinical translational research.

Gel-forming antagonist provides a lasting effect on CGRP-induced vasodilation

Migraine affects ∼15% of the adult population, and the standard treatment includes the use of triptans, ergotamines, and analgesics. Recently, CGRP and its receptor, the CLR/RAMP1 receptor complex, have been targeted for migraine treatment due to their critical roles in mediating migraine headaches. The effort has led to the approval of several anti-CGRP antibodies for chronic migraine treatment. However, many patients still suffer continuous struggles with migraine, perhaps due to the limited ability of anti-CGRP therapeutics to fully reduce CGRP levels or reach target cells. An alternative anti-CGRP strategy may help address the medical need of patients who do not respond to existing therapeutics. By serendipity, we have recently found that several chimeric adrenomedullin/adrenomedullin 2 peptides are potent CLR/RAMP receptor antagonists and self-assemble to form liquid gels. Among these analogs, the ADE651 analog, which potently inhibits CLR/RAMP1 receptor signaling, forms gels at a 6-20% level. Screening of ADE651 variants indicated that residues at the junctional region of this chimeric peptide are important for gaining the gel-forming capability. Gel-formation significantly slowed the passage of ADE651 molecules through Centricon filters. Consistently, subcutaneous injection of ADE651 gel in rats led to the sustained presence of ADE651 in circulation for >1 week. In addition, analysis of vascular blood flow in rat hindlimbs showed ADE651 significantly reduces CGRP-induced vasodilation. Because gel-forming antagonists could have direct and sustained access to target cells, ADE651 and related antagonists for CLR/RAMP receptors may represent promising candidates for targeting CGRP- and/or adrenomedullin-mediated headaches in migraine patients.

Insight into the Web of Stress Responses Triggered at Gene Expression Level by Porphyrin-PDT in HT29 Human Colon Carcinoma Cells

Photodynamic therapy (PDT), a highly targeted therapy with acceptable side effects, has emerged as a promising therapeutic option in oncologic pathology. One of the issues that needs to be addressed is related to the complex network of cellular responses developed by tumor cells in response to PDT. In this context, this study aims to characterize in vitro the stressors and the corresponding cellular responses triggered by PDT in the human colon carcinoma HT29 cell line, using a new asymmetric porphyrin derivative (P2.2) as a photosensitizer. Besides investigating the ability of P2.2-PDT to reduce the number of viable tumor cells at various P2.2 concentrations and fluences of the activating light, we assessed, using qRT-PCR, the expression levels of 84 genes critically involved in the stress response of PDT-treated cells. Results showed a fluence-dependent decrease of viable tumor cells at 24 h post-PDT, with few cells that seem to escape from PDT. We highlighted following P2.2-PDT the concomitant activation of particular cellular responses to oxidative stress, hypoxia, DNA damage and unfolded protein responses and inflammation. A web of inter-connected stressors was induced by P2.2-PDT, which underlies cell death but also elicits protective mechanisms that may delay tumor cell death or even defend these cells against the deleterious effects of PDT.

Targeting Adrenomedullin in Oncology: A Feasible Strategy With Potential as Much More Than an Alternative Anti-Angiogenic Therapy

The development, maintenance and metastasis of solid tumors are highly dependent on the formation of blood and lymphatic vessels from pre-existing ones through a series of processes that are respectively known as angiogenesis and lymphangiogenesis. Both are mediated by specific growth-stimulating molecules, such as the vascular endothelial growth factor (VEGF) and adrenomedullin (AM), secreted by diverse cell types which involve not only the cancerogenic ones, but also those constituting the tumor stroma (i.e., macrophages, pericytes, fibroblasts, and endothelial cells). In this sense, anti-angiogenic therapy represents a clinically-validated strategy in oncology. Current therapeutic approaches are mainly based on VEGF-targeting agents, which, unfortunately, are usually limited by toxicity and/or tumor-acquired resistance. AM is a ubiquitous peptide hormone mainly secreted in the endothelium with an important involvement in blood vessel development and cardiovascular homeostasis. In this review, we will introduce the state-of-the-art in terms of AM physiology, while putting a special focus on its pro-tumorigenic role, and discuss its potential as a therapeutic target in oncology. A large amount of research has evidenced AM overexpression in a vast majority of solid tumors and a correlation between AM levels and disease stage, progression and/or vascular density has been observed. The analysis presented here indicates that the involvement of AM in the pathogenesis of cancer arises from: 1) direct promotion of cell proliferation and survival; 2) increased vascularization and the subsequent supply of nutrients and oxygen to the tumor; 3) and/or alteration of the cell phenotype into a more aggressive one. Furthermore, we have performed a deep scrutiny of the pathophysiological prominence of each of the AM receptors (AM₁ and AM₂) in different cancers, highlighting their differential locations and functions, as well as regulatory mechanisms. From the therapeutic point of view, we summarize here an exhaustive series of preclinical studies showing a reduction of tumor angiogenesis, metastasis and growth following treatment with AM-neutralizing antibodies, AM receptor antagonists, or AM receptor interference. Anti-AM therapy is a promising strategy to be explored in oncology, not only as an anti-angiogenic alternative in the context of acquired resistance to VEGF treatment, but also as a potential anti-metastatic approach.

Adrenomedullin inhibits tumor metastasis and is associated with good prognosis in triple-negative breast cancer patients

BACKGROUND

Cancer metastasis is the major reason for cancer-related deaths, but the mechanism of cancer metastasis still unclear. Adrenomedullin (ADM), a peptide hormone, functions as a local paracrine and autocrine mediator with multiple biological activities, such as angiogenesis, cell proliferation, and anti-inflammation. However, the expression and potential function of ADM in triple-negative breast cancer (TNBC) remain unclear.

METHODS

Real-time polymerase chain reaction and western blotting were performed to examine the expression of ADM in TNBC tissues and cell lines. A total of 458 TNBC tissue samples and adjacent nontumor tissue samples were detected by immunochemistry to determine the correlation between ADM expression and clinicopathological characteristics. We determined the role and mechanistic pathways of ADM in tumor metastasis in cell lines.

RESULTS

Our data showed that ADM expression was noticeably decreased in TNBC samples and cell lines. Low expression levels correlate with an increased risk of recurrence and metastasis. Furthermore, low ADM expression was associated with poor prognosis and was an independent marker for TNBC. In vitro, ADM may decrease cancer cell invasion, which is likely the result of its effect on the cancer cell epithelial-mesenchymal transition.

CONCLUSIONS

Our findings suggest that ADM is a valuable biomarker for TNBC prognosis and an anti-metastasis candidate therapeutic target in triple-negative breast cancer.

Development of chimeric and bifunctional antagonists for CLR/RAMP receptors

CGRP, adrenomedullin (ADM), and adrenomedullin 2 (ADM2) family peptides are important neuropeptides and hormones for the regulation of neurotransmission, vasotone, cardiovascular morphogenesis, vascular integrity, and feto‒placental development. These peptides signal through CLR/RAMP1, 2 and 3 receptor complexes. CLR/RAMP1, or CGRP receptor, antagonists have been developed for the treatment of migraine headache and osteoarthritis pain; whereas CLR/RAMP2, or ADM receptor, antagonists are being developed for the treatment of tumor growth/metastasis. Based on the finding that an acylated chimeric ADM/ADM2 analog potently stimulates CLR/RAMP1 and 2 signaling, we hypothesized that the binding domain of this analog could have potent inhibitory activity on CLR/RAMP receptors. Consistent with this hypothesis, we showed that acylated truncated ADM/ADM2 analogs of 27–31 residues exhibit potent antagonistic activity toward CLR/RAMP1 and 2. On the other hand, nonacylated analogs have minimal activity. Further truncation at the junctional region of these chimeric analogs led to the generation of CLR/RAMP1-selective antagonists. A 17-amino-acid analog (Antagonist 2–4) showed 100-fold selectivity for CLR/RAMP1 and was >100-fold more potent than the classic CGRP receptor antagonist CGRP8-37. In addition, we showed (1) a lysine residue in the Antagonist 2–4 is important for enhancing the antagonistic activity, (2) an analog consisted of an ADM sequence motif and a 12-amino-acid binding domain of CGRP exhibits potent CLR/RAMP1-inhibitory activity, and (3) a chimeric analog consisted of a somatostatin analog and an ADM antagonist exhibits dual activities on somatostatin and CLR/RAMP receptors. Because the blockage of CLR/RAMP signaling prevents migraine pain and suppresses tumor growth/metastasis, further studies of these analogs, which presumably have better access to the tumor microenvironment and nerve endings at the trigeminal ganglion and synovial joints as compared to antibody-based therapies, may lead to the development of better anti-CGRP therapy and alternative antiangiogenesis therapy. Likewise, the use of bifunctional somatostatin-ADM antagonist analogs could be a promising strategy for the treatment of high-grade neuroendocrine tumors by targeting an antiangiogenesis agent to the neuroendocrine tumor microenvironment.

Degranulation of mast cells induced by gastric cancer-derived adrenomedullin prompts gastric cancer progression

Mast cells are prominent components of solid tumors and exhibit distinct phenotypes in different tumor microenvironments. However, their precise mechanism of communication in gastric cancer remains largely unclear. Here, we found that patients with GC showed a significantly higher mast cell infiltration in tumors. Mast cell levels increased with tumor progression and independently predicted reduced overall survival. Tumor-derived adrenomedullin (ADM) induced mast cell degranulation via PI3K-AKT signaling pathway, which effectively promoted the proliferation and inhibited the apoptosis of GC cells in vitro and contributed to the growth and progression of GC tumors in vivo, and the effect could be reversed by blocking interleukin (IL)-17A production from these mast cells. Our results illuminate a novel protumorigenic role and associated mechanism of mast cells in GC, and also provide functional evidence for these mast cells to prevent, and to treat this immunopathogenesis feature of GC.

An Overview of Molecular Profiles in Ulcerative Colitis-Related Cancer

Ulcerative colitis (UC) is an independent risk factor of colorectal cancer (CRC). Both genetic and epigentic events induce a unique molecular profile during the development from UC to UC-related CRC (UCRC). These molecular changes play varied roles in DNA repair, immune response, cell metabolism, and interaction with the microbiota during the carcinogenesis process. This review will systmatically discuss the molecular characteristics of UCRC and point out the future perspectives in this research field.

Small molecules related to adrenomedullin reduce tumor burden in a mouse model of colitis-associated colon cancer

To investigate the contribution of adrenomedullin (AM) and its gene-related peptide, proadrenomedullin N-terminal 20 peptide (PAMP), to the progression and potential treatment of colon cancer we studied the effects of four small molecules (SM) related to AM and PAMP on a mouse model of colon cancer. For each SM, four experimental groups of male mice were used: (i) Control group; (ii) SM group; (iii) DSS group (injected with azoxymethane [AOM] and drank dextran sulfate sodium [DSS]); and (iv) DSS + SM group (treated with AOM, DSS, and the SM). None of the mice in groups i and ii developed tumors, whereas all mice in groups iii and iv developed colon neoplasias. No significant differences were found among mice treated with PAMP modulators (87877 and 106221). Mice that received the AM negative modulator, 16311, had worse colitis symptoms than their control counterparts, whereas mice injected with the AM positive modulator, 145425, had a lower number of tumors than their controls. SM 145425 regulated the expression of proliferation marker Lgr5 and had an impact on microbiota, preventing the DSS-elicited increase of the Bacteroides/Prevotella ratio. These results suggest that treatment with AM or with positive modulator SMs may represent a novel strategy for colon cancer.

The role of adrenomedullin in the pathogenesis of gastric cancer

Adrenomedullin has been shown to be overexpressed in many tumors, including gastric cancer tumors; however, its mechanism of action remains unclear. In this study, we examined the role of adrenomedullin in the pathogenesis of gastric cancer. Using clinical specimens and immunohistochemistry, we found that the expression levels of adrenomedullin and its receptors are inordinately elevated as compared to the adjacent non-tumor gastric tissues. We used siRNA gene silencing, in BGC-823 gastric cancer cell lines, to target adrenomedullin genes, and found that increased adrenomedullin expression results in the proliferation of tumor cells, tumor invasion, and metastasis. Furthermore, we found that under hypoxic conditions, gastric cancer BGC-823 cells exhibit higher expression levels of adrenomedullin and various other related proteins. Our results indicate the involvement of adrenomedullin in microvessel proliferation and partially in the release of hypoxia in solid tumors. Knockdown of adrenomedullin expression, at the protein level, reduced the levels of phosphoprotein kinase B and B-cell lymphoma 2 but increased the levels of cleaved-caspase3 and Bcl 2 associated x protein (Bax). Therefore, we hypothesized siRNA targeting of adrenomedullin genes inhibits various serine/threonine kinases via a signaling pathway that induces cell apoptosis. SiRNA targeting of adrenomedullin genes and green fluorescent control vectors were used to transfect BGC-823 cells, and western blot analyses were used to detect changes in the rates of autophagy in related proteins using confocal laser scanning microscopy. No significant changes were detected. Therefore, the knockdown of adrenomedullin and its receptors may represent a novel treatment strategy for gastric cancer.

Vasoactive peptides associate with treatment outcome ofbevacizumab-containing therapy in metastatic colorectal cancer

BACKGROUND

Hypertension is a common early adverse event of anti-angiogenic treatment of cancer and may associate with treatment response. However, blood pressure measurement as a surrogate response biomarker has methodological limitations, and predictive biomarkers of angiogenesis inhibitors are lacking. In disease associated with hypertension, vasoactive peptides have been linked to cardiovascular pressure load. Here, we have explored potential associations between circulating levels of vasoactive peptides and tumor response during bevacizumab-containing treatment of colorectal cancer.

MATERIAL AND METHODS

Metastatic colorectal cancer (mCRC) patients with available best objective response (ORR) and time to tumor progression (TTP) data were included from a randomized clinical trial investigating maintenance therapy after first line chemotherapy plus bevacizumab. Midregional-pro-adrenomedullin (MR-proADM), midregional-pro-atrial-natriuretic-peptide (MR-proANP), and C-terminal-prepro-vasopressin (Copeptin) vasoactive peptide concentrations were measured in plasma at baseline and after 6 weeks of chemotherapy and bevacizumab treatment (n = 97). We determined associations among clinical outcome (ORR and TTP), peptide levels, and hypertension (NCI-CTCAE 4.0 criteria), using Spearman's test, multiple linear regression, and Mann-Whitney's test.

RESULTS

Increasing levels of vasoactive peptides from baseline and after six weeks of treatment were associated with improved treatment outcome (MR-proADM: ORR, p = .0003; TTP, p = .05; MR-proANP: ORR, p = .05; TTP, p = .03; Copeptin: ORR, p = .10; TTP, p = .02). Patients with increasing levels of all three peptides (n = 28) versus increasing levels of one or two peptides (n = 59) showed a median TTP of 284 and 225 d, respectively (p = .02).

CONCLUSIONS

Our results suggest that increasing systemic levels of vasoactive peptides associate with improved tumor response and TTP in mCRC patients treated with a bevacizumab-containing regimen. These findings support the proposed link between the tumor vasculature and the cardiovascular system of the host. This should motivate further studies that investigate the potential role of vasoactive peptides as a novel class of dynamic biomarkers in the treatment of cancer.

Epieriocalyxin A Induces Cell Apoptosis Through JNK and ERK1/2 Signaling Pathways in Colon Cancer Cells

Colorectal cancer is one of the most commonly diagnosed cancers in the world. Currently, drug resistance of cancer cell to chemotherapy is a major cause for cancer recurrence and death of the patients; therefore, new therapeutic strategy is required to improve the care of colorectal cancer patients. The Chinese herb, Isodon eriocalyx, has been used a therapeutic for a long time in China. In this study, we showed that Epieriocalyxin A (EpiA), a diterpenoid isolated from I. eriocalyx, suppressed Caco-2 colon cancer cell growth. EpiA induced annexin V flipping in cell membrane and DNA fragment. We also showed that EpiA induced the generation of ROS in cells, as well as damage of the mitochondrial membrane. Western blot results showed that both JNK and ERK1/2 activation was decreased after EpiA treatment in a dose-dependent manner. EpiA increased the expression of caspase 3 and Bax, and decreased Bcl2 expression. Our results suggest that EpiA is a novel compound that induces colon cancer apoptosis. EpiA could be a potential drug for colon cancer therapy in the future.

BCAM and LAMA5 Mediate the Recognition between Tumor Cells and the Endothelium in the Metastatic Spreading of KRAS-Mutant Colorectal Cancer

PURPOSE

KRAS mutations confer adverse prognosis to colorectal cancer, and no targeted therapies have shown efficacy in this patient subset. Paracrine, nongenetic events induced by KRAS-mutant tumor cells are expected to result in specific deregulation and/or relocation of tumor microenvironment (TME) proteins, which in principle can be exploited as alternative therapeutic targets.

EXPERIMENTAL DESIGN

A multimodal strategy combining ex vivo/in vitro phage display screens with deep-sequencing and bioinformatics was applied to uncover TME-specific targets in KRAS-mutant hepatic metastasis from colorectal cancer. Expression and localization of BCAM and LAMA5 were validated by immunohistochemistry in preclinical models of human hepatic metastasis and in a panel of human specimens (n = 71). The antimetastatic efficacy of two BCAM-mimic peptides was evaluated in mouse models. The role of BCAM in the interaction of KRAS-mutant colorectal cancer cells with TME cells was investigated by adhesion assays.

RESULTS

BCAM and LAMA5 were identified as molecular targets within both tumor cells and TME of KRAS-mutant hepatic metastasis from colorectal cancer, where they were specifically overexpressed. Two BCAM-mimic peptides inhibited KRAS-mutant hepatic metastasis in preclinical models. Genetic suppression and biochemical inhibition of either BCAM or LAMA5 impaired adhesion of KRAS-mutant colorectal cancer cells specifically to endothelial cells, whereas adhesion to pericytes and hepatocytes was unaffected.

CONCLUSIONS

These data show that the BCAM/LAMA5 system plays a functional role in the metastatic spreading of KRAS-mutant colorectal cancer by mediating tumor-TME interactions and as such represents a valuable therapeutic candidate for this large, currently untreatable patient group. Clin Cancer Res; 22(19); 4923-33. ©2016 AACR.

Down-regulation of malignant potential by alpha linolenic acid in human and mouse colon cancer cells

Omega-3 fatty acids (also called ω-3 fatty acis or n-3 fatty acid) are polyunsaturated fatty acids (PUFAs) with a double bond (C=C) at the third carbon atom from the end of the carbon chain. Numerous test tube and animal studies have shown that omega-3 fatty acids may prevent or inhibit the growth of cancers, suggesting that omega-3 fatty acids are important in cancer physiology. Alpha-linolenic acid (ALA) is one of an essential omega-3 fatty acid and organic compound found in seeds (chia and flaxseed), nuts (notably walnuts), and many common vegetable oils. ALA has also been shown to down-regulate cell proliferation of prostate, breast, and bladder cancer cells. However, direct evidence that ALA suppresses to the development of colon cancer has not been studied. Also, no previous studies have evaluated whether ALA may regulate malignant potential (adhesion, invasion and colony formation) in colon cancer cells. In order to address the questions above, we conducted in vitro studies and evaluated whether ALA may down-regulate malignant potential in human (HT29 and HCT116) and mouse (MCA38) colon cancer cell lines. We observed that treatment with 1-5 mM of ALA inhibits cell proliferation, adhesion and invasion in both human and mouse colon cancer cell lines. Interestingly, we observed that ALA did not decrease total colony numbers when compared to control. By contrast, we found that size of colony was significantly changed by ALA treatment when compared to control in all colon cancer cell lines. We suggest that our data enhance our current knowledge of ALA's mechanism and provide crucial information to further the development of new therapies for the management or chemoprevention of colon cancer.

Adrenomedullin and tumour microenvironment

Adrenomedullin (AM) is a regulatory peptide whose involvement in tumour progression is becoming more relevant with recent studies. AM is produced and secreted by the tumour cells but also by numerous stromal cells including macrophages, mast cells, endothelial cells, and vascular smooth muscle cells. Most cancer patients present high levels of circulating AM and in some cases these higher levels correlate with a worst prognosis. In some cases it has been shown that the high AM levels return to normal following surgical removal of the tumour, thus indicating the tumour as the source of this excessive production of AM. Expression of this peptide is a good investment for the tumour cell since AM acts as an autocrine/paracrine growth factor, prevents apoptosis-mediated cell death, increases tumour cell motility and metastasis, induces angiogenesis, and blocks immunosurveillance by inhibiting the immune system. In addition, AM expression gets rapidly activated by hypoxia through a HIF-1α mediated mechanism, thus characterizing AM as a major survival factor for tumour cells. Accordingly, a number of studies have shown that inhibition of this peptide or its receptors results in a significant reduction in tumour progression. In conclusion, AM is a great target for drug development and new drugs interfering with this system are being developed.