Blockade of growth hormone receptor signaling by using pegvisomant: A functional therapeutic strategy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive neoplasm with poor clinical outcome because most patients present at an advanced stage, at which point curative surgical options, such as tumor excision or liver transplantation, are not feasible. Therefore, the majority of HCC patients require systemic therapy. Nonetheless, the currently approved systemic therapies have limited effects, particularly in patients with advanced and resistant disease. Hence, there is a critical need to identify new molecular targets and effective systemic therapies to improve HCC outcome. The liver is a major target of the growth hormone receptor (GHR) signaling, and accumulating evidence suggests that GHR signaling plays an important role in HCC pathogenesis. We tested the hypothesis that GHR could represent a potential therapeutic target in this aggressive neoplasm. We measured GH levels in 767 HCC patients and 200 healthy controls, and then carried out clinicopathological correlation analyses. Moreover, specific inhibition of GHR was performed in vitro using siRNA and pegvisomant (a small peptide that blocks GHR signaling and is currently approved by the FDA to treat acromegaly) and in vivo, also using pegvisomant. GH was significantly elevated in 49.5% of HCC patients, and these patients had a more aggressive disease and poorer clinical outcome (P<0.0001). Blockade of GHR signaling with siRNA or pegvisomant induced substantial inhibitory cellular effects in vitro. In addition, pegvisomant potentiated the effects of sorafenib (P<0.01) and overcame sorafenib resistance (P<0.0001) in vivo. Mechanistically, pegvisomant decreased the phosphorylation of GHR downstream survival proteins including JAK2, STAT3, STAT5, IRS-1, AKT, ERK, and IGF-IR. In two patients with advanced-stage HCC and high GH who developed sorafenib resistance, pegvisomant caused tumor stability. Our data show that GHR signaling represents a novel “druggable” target, and pegvisomant may function as an effective systemic therapy in HCC. Our findings could also lead to testing GHR inhibition in other aggressive cancers.

Disruption of Growth Hormone Receptor Signaling Abrogates Hepatocellular Carcinoma Development

Introduction

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancers. It is an aggressive neoplasm with dismal outcome because most of the patients present with an advanced-stage disease, which precludes curative surgical options. Therefore, these patients require systemic therapies that typically induce small improvements in overall survival. Hence, it is crucial to identify new and promising therapeutic targets for HCC to improve the current outcome. The liver is a key organ in the signaling cascade triggered by the growth hormone receptor (GHR). Previous studies have shown that GHR signaling stimulates the proliferation and regeneration of liver cells and tissues; however, a definitive role of GHR signaling in HCC pathogenesis has not been identified.

Methods

In this study, we used a direct and specific approach to analyze the role of GHR in HCC development. This approach encompasses mice with global (Ghr-/- ) or liver-specific (LiGhr-/- ) disruption of GHR expression, and the injection of diethylnitrosamine (DEN) to develop HCC in these mice.

Results

Our data show that DEN induced HCC in a substantial majority of the Ghr+/+ (93.5%) and Ghr +/- (87.1%) mice but not in the Ghr-/- (5.6%) mice (P < 0.0001). Although 57.7% of LiGhr-/- mice developed HCC after injection of DEN, these mice had significantly fewer tumors than LiGhr+/+ (P < 0.001), which implies that the expression of GHR in the liver cells might increase tumor burden. Notably, the pathologic, histologic, and biochemical characteristics of DEN-induced HCC in mice resembled to a great extent human HCC, despite the fact that etiologically this model does not mimic this cancer in humans. Our data also show that the effects of DEN on mice livers were primarily related to its carcinogenic effects and ability to induce HCC, with minimal effects related to toxic effects.

Conclusion

Collectively, our data support an important role of GHR in HCC development, and suggest that exploiting GHR signaling may represent a promising approach to treat HCC.

Recombinant human growth hormone (rhGH) treatment of MKN-45 xenograft mice improves nutrition status and strengthens immune function without promoting tumor growth

The aim of this study was to clarify the combined effects and dose-effect relationships of rhGH on tumor growth, nutrition status, and immune function in MKN-45 xenograft mice. In this study, animal models were induced in nude mice using the subcutaneous transplantation of MKN-45 cells, and rhGH was injected daily for 14 days. Three rhGH treatment dosages were set with reference to the equivalent dosage converted from human clinical dosage, including 2 IU (0.67 mg), 10 IU (3.35 mg) and 50 IU (16.75 mg) per kg body weight. The tumor volume, body weight and food intake were measured every two or three days. After 14 days of rhGH treatment, the tumors were isolated and weighed. The expression levels of Ki-67, vascular endothelial growth factor (VEGF) and CD31in tumor tissues were detected by immunohistochemistry (IHC). The protein expression levels of pJAK2, JAK2, pSTAT3, STAT3, pAKT, AKT, pERK and ERK were measured by western blotting. The percentage of active NK cells in peripheral blood mononuclear cells (PBMCs) was detected by fluorescence-activated cell sorting (FACS). The results showed that rhGH had improved the food intake, increased the body weight and strengthened the immune function of MKN-45 xenograft mice but had not promote tumor growth. MKN-45 xenograft mice treated with rhGH at a higher dosage gained more weight, while those treated with rhGH at a lower dosage showed stronger immune function and smaller tumor volume.

Human growth hormone and human prolactin function as autocrine/paracrine promoters of progression of hepatocellular carcinoma

The death rates of hepatocellular carcinoma (HCC) are extremely high due to the paucity of therapeutic options. Animal models and anecdotal clinical evidence indicate a potential role of hGH and hPRL in HCC. However, the prognostic relevance and the functional role of tumor expression of these hormones in human HCC are not defined. Herein, we analyzed the mRNA and protein expression of hGH and hPRL in histopathological samples of non-neoplastic liver and HCC by in situ hybridization, PCR and immunohistochemistry techniques. Increased mRNA and protein expression of both hormones was observed in HCC compared with non-neoplastic liver tissues. hGH expression was significantly associated with tumor size and tumor grade. No significant association was observed between the expression of hPRL and any histopathological features. Amplification of both hGH and hPRL genes in HCC was observed when compared to non-neoplastic tissue. Expression of both hGH and hPRL was associated with worse relapse-free and overall survival in HCC patients. In vitro and in vivo functional assays performed with HCC cell lines demonstrated that autocrine expression of hGH or hPRL in HCC cells increased STAT3 activation, oncogenicity and tumor growth while functional antagonism with hGH-G120R significantly reduced these parameters. Hence, tumor expression of hGH/hPRL is associated with a worse survival outcome for patients with HCC and hGH/hPRL function as autocrine/paracrine promoters of HCC progression.

Molecular Mechanisms and Targets of Therapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. HCC develops through a multistep process that involves the local tumor microenvironment, intracellular signaling pathways, and altered metabolic system that allows the cancer proliferation. Understanding the mechanisms of tumor development and progression is critical to developing improved therapies aimed at better survival. This article reviews the molecular mechanisms of HCC development and highlights the potential therapeutic targets for treatments.

Integrated therapies for osteoporosis and sarcopenia: from signaling pathways to clinical trials

Sarcopenia and osteoporosis are two sides of the same coin. They represent different aspects of the same age-related process of musculoskeletal atrophy and together culminate in falls, fractures, deconditioning, and increased mortality in older individuals. However, the current therapeutic approach to the prevention of minimal trauma fracture is unilateral and focuses solely on bone. In theory, an integrated approach that recognizes the interaction between muscle and bone could break the vicious cycle of their combined involution and more effectively minimize falls/fractures. In this review, signaling pathways and cross-talk mechanisms that integrate bone/muscle, and the emergence of novel therapies that exploit these pathways to target osteoporosis/sarcopenia will be discussed. In broad terms, these agents act on nuclear receptors (e.g., VDR, AR) or transmembrane receptors (e.g., activins, GH/IGF-1) expressed in muscle and bone, and seek to alter biologic responses to musculoskeletal aging, loading, and injury. Challenges in the development of these dual bone-muscle therapies, early clinical trials examining their safety/efficacy, and novel targets that hold promise in the reversal of musculoskeletal aging will be discussed.

The GH-IGF-SST system in hepatocellular carcinoma: biological and molecular pathogenetic mechanisms and therapeutic targets

Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide. Different signalling pathways have been identified to be implicated in the pathogenesis of HCC; among these, GH, IGF and somatostatin (SST) pathways have emerged as some of the major pathways implicated in the development of HCC. Physiologically, GH-IGF-SST system plays a crucial role in liver growth and development since GH induces IGF1 and IGF2 secretion and the expression of their receptors, involved in hepatocytes cell proliferation, differentiation and metabolism. On the other hand, somatostatin receptors (SSTRs) are exclusively present on the biliary tract. Importantly, the GH-IGF-SST system components have been indicated as regulators of hepatocarcinogenesis. Reduction of GH binding affinity to GH receptor, decreased serum IGF1 and increased serum IGF2 production, overexpression of IGF1 receptor, loss of function of IGF2 receptor and appearance of SSTRs are frequently observed in human HCC. In particular, recently, many studies have evaluated the correlation between increased levels of IGF1 receptors and liver diseases and the oncogenic role of IGF2 and its involvement in angiogenesis, migration and, consequently, in tumour progression. SST directly or indirectly influences tumour growth and development through the inhibition of cell proliferation and secretion and induction of apoptosis, even though SST role in hepatocarcinogenesis is still opened to argument. This review addresses the present evidences suggesting a role of the GH-IGF-SST system in the development and progression of HCC, and describes the therapeutic perspectives, based on the targeting of GH-IGF-SST system, which have been hypothesised and experimented in HCC.

The effects of recombinant human GH on promoting tumor growth depend on the expression of GH receptor in vivo

Cancer-related malnutrition is a mortal threat to gastric carcinoma patients. However, conventional nutrition treatment is not effective for recovery. Recombinant human GH (rhGH) is widely accepted clinically to treat severe malnutrition caused by non-malignant diseases, but not approved to treat malignant diseases due to the safety concern. To explore the safety of rhGH on gastric cancer, we assessed the effect of rhGH on two tumor-bearing mice models in vivo established by human gastric adenoma cell lines of SGC-7901 and MKN-45. VEGF expression in tumor tissues was detected using immunohistochemistry. The expression of GH receptor (Ghr), Jak-2, Stat3, Vegf, Hif-1α, Fgf, and Mmp-2 was measured by RT-PCR and protein expression of STAT3, phosphorylated STAT3, VEGF, HIF-1α, and MMP-2 was measured by western blotting. The immunocytochemistry results showed that the GHR expression of SGC-7901 was strongly positive (GHR(+++)), while GHR expression of MKN-45 was regarded as negative (GHR(-)). After 14 days of rhGH treatment in SGC-7901 (GHR(+++)) tumor-bearing mice, we found that the tumor growth was significantly increased, and the expressions of downstream factors and VEGF were increased. However, in MKN-45 (GHR(-)) tumor-bearing mice, tumor growth was not significantly increased by rhGH, but tumor-free body weight was increased especially in high-dose rhGH-treated group (P<0.05). These findings suggest that the level of GHR expression is a key target that influences the effectiveness of rhGH on promoting the growth of gastric cancer and angiogenesis. rhGH may promote the activation of tumor angiogenesis factors through the Jak-2-STAT3 pathway.