The pathogenesis of bone metastasis in solid tumors: a review

Owing to its frequent occurrence and severe clinical picture, bone metastasis is an important problem in the clinical course of tumor diseases. Bone metastasis develops when the physiological remodeling process is disrupted by tumor cells via the same molecular mechanisms used by native bone cells. The process includes molecular crosstalk between osteocytes and osteoblasts and osteoclasts. Osteolytic bone metastasis, most often seen in breast cancer, is characterized by promoted differentiation and function of osteoclasts and reduced osteoblast function. Tumor cells take advantage of factors released by bone tissue resorption, thus establishing a vicious cycle that promotes the metastatic process. In osteoblastic metastasis, most often seen in prostate cancer, osteoblast function and differentiation are promoted, while osteoclast activity is reduced, resulting in net gain of bone tissue. Mechanisms involved in the early stages of bone metastasis and cancer cell dormancy have been understudied, and their exploration may pave the way for potential therapeutic strategies. Tumor affects the bone marrow microenvironment via exosomes, soluble factors, and membrane-bound ligands. In this way, an initial lesion is established, which after a variable duration of disseminated tumor cells dormancy progresses to an overt condition. The current review deals with basic mechanisms involved in bone metastasis formation and propagation. We illustrated a disparity between the diversity and number of factors included in the disease pathophysiology and the number of available and developing therapeutic options. We also examined new therapeutic strategies affecting molecular pathways.

The bone is the third most frequent metastasis site, behind the lungs and liver (1). Given common clinical manifestation and a high degree of related disability, bone metastases pose a serious problem in the clinical course of tumor diseases. Since bone metastases present frequently in tumor diseases, they have an important predictive role. Namely, the median survival from the diagnosis of bone metastases is 12-53 months for prostate cancer, 19-25 months for breast cancer, 48 months for thyroid cancer, 6-7 months for lung cancer, 6 months for melanoma, 6-9 months for bladder cancer, and 12 months for kidney cancer (2).All known mechanisms taking part in bone metastasis process are related to the disorders of physiological bone remodeling. Although the traditional division of bone metastases into osteolytic and osteoblastic is still widely accepted, these categories are increasingly viewed as only extremes of a continuum (3).     

Identification of a novel flow-mediated gene expression signature in patients with bicuspid aortic valve

Individuals with bicuspid aortic valve (BAV) are at significantly higher risk of developing serious aortic complications than individuals with tricuspid aortic valves (TAV). Studies have indicated an altered aortic blood flow in patients with BAV; however, the extent to which altered flow influences the pathological state of BAV aorta is unclear. In the present study, we dissected flow-mediated aortic gene expression in patients undergoing elective open heart surgery. A large collection of public microarray data sets were firstly screened for consistent co-expression with five well-characterized flow-regulated genes (query genes). Genes with co-expression probability of >0.5 were selected and further analysed in expression profiles (127 arrays) from ascending aorta of BAV and TAV patients. Forty-four genes satisfied two filtering criteria: a significant correlation with one or more of the query genes (R?>?0.40) and differential expression between patients with BAV and TAV. No gene fulfilled the criteria in mammary artery (88 arrays), an artery not in direct contact with the valve. Fifty-five percent of the genes significantly altered between BAV and TAV patients showed differential expression between two identified flow regions in the rat aorta. A large proportion of the identified genes were related to angiogenesis and/or wound healing, with pro-angiogenesis genes downregulated and inhibitory genes upregulated in patients with BAV. Moreover, differential expression of ZFP36, GRP116 and PKD2 was confirmed using immunohistochemistry. Implementing a new strategy, we have demonstrated an angiostatic gene expression signature in patients with BAV, indicating impaired wound healing in these patients, potentially involved in BAV-associated aortopathy.     

Bone marrow metastasis in solid tumors

Bone marrow examination has been increasingly useful in documenting metastatic involvement of tumors. A retrospective analysis of 73 cases of bone marrow metastasis of solid tumors revealed 27 cases in the pediatric age group and 46 cases in the adult age group. All 27 pediatric cases were that of neuroblastoma. In the adult bone marrow metastasis from carcinoma prostate were present in 22 cases followed by carcinoma breast in 13 cases. Rest were 5 cases of carcinoma lung, 4 cases of carcinoma colon, 1 case each of carcinoma thyroid and renal cell carcinoma. A number of associated features were observed which may help to suggest bone marrow metastasis, in the absence of tumor cells in the bone marrow.     

Interferon signature gene expression is correlated with autoantibody profiles in patients with incomplete lupus syndromes

Interferon (IFN) signature genes have been shown to be expressed highly in peripheral blood of patients with systemic lupus erythematosus (SLE), especially in the presence of active disease. However, the expression of this gene signature in individuals with incomplete forms of lupus and the pathogenic relationship between IFN signature genes and autoantibody production have not been explored fully. In the present study, we examined the gene expression and autoantibody profiles of patients diagnosed with incomplete lupus erythematosus (ILE) to determine correlations of the gene expression signature with autoantibody production. Gene expression analysis was carried out on the 24K Illumina Human Refseq‐8 arrays using blood samples from 84 subjects, including patients with SLE (n = 27) or ILE (n = 24), first‐degree relatives (FDR) of these patients (n = 22) and non‐autoimmune control (NC) individuals (n = 11). Autoantibody expression was measured using standard immunoassays and autoantigen proteomic arrays. Up‐regulation of a set of 63 IFN signature genes was seen in 83% of SLE patients and 50% of ILE patients. High levels of IFN gene expression in ILE and SLE showed significant correlations with the expression of a subset of IgG autoantibodies, including chromatin, dsDNA, dsRNA, U1snRNP, Ro/SSA, La/SSB, topoisomerase I and Scl 70, while low IFN levels were correlated with immunoglobulin (Ig)M autoreactivity. These studies suggest that in patients with ILE the IFN gene expression signature may identify a subset of these individuals who are at risk for disease progression. Furthermore, high levels of alpha IFN may promote autoantibody class‐switch from IgM to the more pathogenic IgG class.     

c-Src expression is predictive of poor prognosis in breast cancer patients with bone metastasis, but not in patients with visceral metastasis

c-Src expression is critical for breast cancer progression and it is particularly important for bone metastasis. In this study, we aimed to evaluate the effect of c-Src on prognosis in metastatic breast cancer patients, and to conduct subgroup analysis to explore the role of c-Src in bone metastasis and visceral metastasis respectively. We analyzed a total of 102 paraffin-embedded primary tumor tissue sections from metastatic breast cancer patients using immunohistochemical staining for c-Src, including 61 patients with bone metastases. Clinical data were collected retrospectively. We utilized survival analysis and the Cox proportional hazards model to explore the prognostic value of c-Src expression in metastatic breast cancer. The c-Src expression rate was 54.9% in the 102 metastatic breast cancer patients. Patients who exhibited c-Src expression demonstrated poor progression-free survival (PFS) (p = 0.044) and disease-specific survival (DSS) (p = 0.017). Subgroup analysis demonstrated that c-Src positive patients exhibited significantly worse bone metastasis-free survival (p = 0.027) and DSS (p = 0.024), whereas in patients with non-bone metastasis no significant difference was observed in PFS (p = 0.819) and DSS (p = 0.381). Multivariate analysis demonstrated that c-Src expression was an independent predictor of DSS for patients with bone metastasis. Our findings demonstrate that c-Src expression is a potential independent predictor of poor prognosis in breast cancer patients with bone metastasis.     

Population study of expression of thymidylate synthase and dihydropyrimidine dehydrogenase in patients with solid tumors

Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) has been suggested to be sensitivity-limiting factors of 5-fluorouracil therapy in cancer patients. We conducted a large-scale population study on the activity of TS and DPD in patients with various solid tumors. A total of 2590 clinically removed tumors, consisting of 1112 colon, 724 gastric, 520 breast, and 236 non-small cell lung cancers, were provided to measure TS and DPD activity. TS activity in the gastric, colon, and non-small cell lung cancers was significantly higher than in matched non-cancerous tissue (P<0.0002), but there was no difference in TS expression between tumor and non-cancerous tissue from breast cancer patients. Gastric, breast, and non-small cell lung cancers showed significantly higher DPD activity than their corresponding non-cancerous tissues, but colon cancers did not. There was no correlation between TS activity and DPD activity, and thus each enzyme was considered to be an independent sensitivity-limiting factor for 5-fluorouracil therapy. The median TS activity and median DPD activity in all specimens including gastric, colorectal, breast, and non-small cell lung cancers tested were 0.041 and 110.1 pmol/mg protein, respectively. We classified each of the type of carcinoma into 4 groups by using the median activity of TS and DPD as the cutoff values: a low TS/low DPD group, high TS/low DPD group, low TS/high DPD group, and high TS/high DPD group. About 50% of the gastric, 47% of the colon, 70% of the breast and 30% of the non-small cell lung cancers had high TS activity, and 60% of the gastric, 40% of the colon, 48% of the breast, and 87% of the lung cancers had high DPD activity. Moreover, breast cancer was characterized by high TS activity and lung cancer by high DPD activity as compared with gastric and colon cancers, and their high activity levels may influence to the effectiveness of 5-fluorouracil against cancers of these organs. The results for expression of TS and DPD in clinically dissected tumors would be useful to estimate the efficacy of 5-fluorouracil in the treatment of cancer patients.     

Aldehyde dehydrogenase as a marker and functional mediator of metastasis in solid tumors

There is accumulating evidence indicating that aldehyde dehydrogenase (ALDH) activity selects for cancer cells with increased aggressiveness, capacity for sustained proliferation, and plasticity in primary tumors. However, emerging data also suggests an important mechanistic role for the ALDH family of isoenzymes in the metastatic activity of tumor cells. Recent studies indicate that ALDH correlates with either increased or decreased metastatic capacity in a cellular context-dependent manner. Importantly, it appears that different ALDH isoforms support increased metastatic capacity in different tumor types. This review assesses the potential of ALDH as biological marker and mechanistic mediator of metastasis in solid tumors. In many malignancies, most notably in breast cancer, ALDH activity and expression appears to be a promising marker and potential therapeutic target for treating metastasis in the clinical setting.     

侵袭性骨肿瘤中RB基因及其蛋白产物表达的研究

目的探讨抑癌基因ＲＢ的改变与骨肿瘤的关系。方法采用地高辛标记的ＲＢｃＤＮＡ探针对３４例侵袭性骨肿瘤组织及同体正常软组织进行ＳｏｕｔｈｅｒｎＢｌｏｔ检测，同时应用ＬＳＡＢ免疫组化法对９９例侵袭性骨肿瘤及１４例瘤旁软组织进行ＲＢ蛋白表达的检测。结果２１例骨肉瘤中有９例可检出ＲＢ基因的结构异常（４２．９％），ＲＢ蛋白的缺失仅在２６．９％（７／２６）的骨肉瘤和２１．７％（５／２３）的软骨肉瘤中检测到，良性的骨巨细胞瘤和软骨母细胞瘤中未检出ＲＢ蛋白的缺失，其二者差异有意义（Ｐ＜０．０５）；分化差、异型性明显的骨肉瘤细胞其ＲＢ蛋白表达为阴性，低分化的软骨肉瘤及间叶性软骨肉瘤其ＲＢ蛋白亦多为阴性。结论ＲＢ基因结构的异常、ＲＢ蛋白的缺失，可能与骨的恶性肿瘤的发生及其演进有关。     

Prognostic value of long non-coding RNA FOXD2-AS1 expression in patients with solid tumors

BackgroundAlthough increasing evidence has revealed that FOXD2-AS1 overexpression exists in various solid tumors, the value of FOXD2-AS1 as a prognostic marker in such cancers remains uncertain. Accordingly, the present research aimed to assess the association of FOXD2-AS1 with cancer prognosis and predict the biological function of FOXD2-AS1.MethodsWe systematically retrieved PubMed, PMC, Web of Science, EMBASE and Wiley Online Library databases for eligible articles published up to December 2018. Pooled hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (95%CIs) were calculated to evaluate the correlation of FOXD2-AS1 expression with overall survival (OS), disease free survival (DFS) and clinicopathological characteristics. We also used five Gene Expression Omnibus (GEO) datasets from breast cancer patients to explore the relationship between FOXD2-AS1 expression and prognosis. Finally, we validated FOXD2-AS1 expression in various carcinomas and predicted its biological function based on the public databases.ResultsA total of 13 studies with 2502 tumor patients were included. The pooled HRs demonstrated that FOXD2-AS1 overexpression was significantly associated with unfavorable OS (HR = 1.39, 95%CI: 1.23–1.57, p < 0.001) and DFS (HR = 2.24, 95%CI: 1.55–3.23, p < 0.001) in tumor patients. The pooled ORs indicated that FOXD2-AS1 upregulation was related to large tumor size (OR = 1.53, 95%CI: 1.26–1.85, p < 0.001), deep invasion depth (OR = 1.99, 95%CI: 1.53–2.58, p < 0.001), distant metastasis (OR = 2.03, 95%CI: 1.69–2.43, p < 0.001) and advanced TNM stage (OR = 1.35, 95%CI: 1.06–1.72, p = 0.0150), but not to lymph node metastasis nor differentiation. Moreover, a similar pooled result for the OS of breast cancer patients was obtained (HR = 1.55, 95%CI: 1.14–2.11, p = 0.0052) by analyzing GEO data. Finally, elevated FOXD2-AS1 expression in various solid tumor tissues was verified based on The Cancer Genome Atlas (TCGA) data. Further functional prediction demonstrated that FOXD2-AS1 may participate in some cancer-related pathways.ConclusionElevated FOXD2-AS1 expression was associated with poor survival in patients with solid tumors and may serve as a potential prognostic biomarker for a variety of cancers.     

Loss of KAI1/CD82 expression in bone and soft tissue tumors is not associated with lung metastasis

The KAI1 gene has been identified as a metastasis suppressor gene in human prostate cancer. Decrease or loss of KAI1/CD82 expression has been shown to be associated with poorer prognosis and metastasis in carcinomas of various organs. The purpose of this study was to examine whether KAI1/CD82 is expressed in bone and soft tissue tumors, and whether it is associated with metastasis to the lungs. Immunohistochemically, KAI1/CD82 expression in benign and malignant soft tissue tumors was noted in 83% and 37% of cases, respectively. KAI1/CD82 was- also expressed in benign bone tumors and osteosarcomas in 67% and 36% of the cases, respectively. Four (40%) of 10 osteosarcoma cases with no lung metastasis and one (25%) of four osteosarcoma cases with lung metastasis were positive for KAI1/CD82, respectively. Metastasis of osteosarcoma cells to the lungs was not correlated with the loss of KAI1/CD82 in osteosarcoma cells.     

Activin A circulating levels in patients with bone metastasis from breast or prostate cancer

Recent studies have highlighted that Activin A, a member of the transforming growth factor-β (TGF-β) superfamily, may be involved in the regulation of osteoblastic activity and in osteoclast differentiation. Therefore, we have investigated the clinical significance of its circulating levels in patients with bone metastasis. Activin A serum concentrations were determined, by a commercially available enzyme-linked immunosorbent assay kit, in 72 patients with breast cancer (BC) or prostatic cancer (PC) with (BM+) or without (BM−) bone metastases, in 15 female patients with age-related osteoporosis (OP), in 20 patients with benign prostatic hypertrophy (BPH) and in 48 registered healthy blood donors (HS) of both sex (25 female and 23 male). Activin A serum concentrations were significantly increased in BC or PC patients as compared to OP (P < 0.0001) or BPH (P = 0.045), respectively, or to sex matched HS (P < 0.0001). Additionally, these levels resulted more elevated in PC patients as compared to BC patients (P = 0.032). Interestingly, Activin A was significantly higher in BM+ patients than in BM− patients (BC, P = 0.047; PC, P = 0.016). In BC patients, a significant correlation was observed only between Activin A and number of bone metastases (P = 0.0065) while, in PC patients, Activin A levels were strongly correlated with the Gleason score (P = 0.011) or PSA levels (P = 0.0001) and, to a lessen extent, with the number of bone metastases (P = 0.056). Receiver operating characteristic curve (ROC) analysis showed a fair diagnostic accuracy of Activin A to discriminate between BM+ and BM− patients (BC: AUC = 0.71 ± 0.09, P = 0.03; PC: AUC = 0.73 ± 0.081, P = 0.005). These findings indicate that Activin A may be implicated in the pathogenesis of bone metastasis. Therefore, this cytokine may be considered a novel potential target for a more selective therapeutic approach in the treatment of skeletal metastasis and may be also useful as additional biochemical marker of metastatic bone disease.     

Molecular mechanisms of lymphatic metastasis in solid tumors of the gastrointestinal tract

Tumor cell dissemination from the primary tumor site to distant organs is one of the characteristic properties of malignant tumors and represents a crucial step in the progression of disease. Although the pattern of spread may vary in different types of carcinomas, dissemination via the lymphatic system represents a common event in metastasis. The extent of lymph node metastasis is one of the major determinants for the prognosis of patients with gastrointestinal carcinomas and guides the therapeutically management. During the last decades, significant attention has been given to the molecular mechanisms that control lymphatic metastasis. The process of lymphangiogenesis has come into the focus. Lymphangiogenesis, the formation of newly lymphatics, comprises a series of complex cellular events and is controlled by a balance between pro- and anti-lymphangiogenic signals. This article will briefly describe the lymphatic system and then provide an overview of the molecular players involved in tumor lymphangiogenesis.     

急性淋巴细胞白血病患者骨髓单个核细胞TAp63基因的表达

背景：据作者查新检索,国内外有关急性白血病患者骨髓单个核细胞TAp63基因表达的报道罕见。 目的：观察急性淋巴细胞白血病患者骨髓单个核细胞TAp63基因的表达及其意义。 方法：50例急性淋巴细胞白血病患者,其中32例急性B淋巴细胞白血病,18例急性T淋巴细胞白血病。同期选择27例非恶性血液病患者作为对照。取肝素抗凝的骨髓液2~4 mL,用Ficoll液分离骨髓单个核细胞,半定量反转录聚合酶链反应法检测TAp63的表达。 结果与结论：50例急性淋巴细胞白血病患者有49例表达TAp63,急性淋巴细胞白血病组明显高于非恶性血液病组(P < 0.05),急性B淋巴细胞白血病表达水平显著高于急性T淋巴细胞白血病(P < 0.05)。动态观察了5例初治急性淋巴细胞白血病化疗后不同阶段TAp63的表达变化,发现初治时TAp63表达,缓解后低表达或不表达,复发后又表达。结果表明TAp63在急性淋巴细胞白血病患者骨髓单个核细胞的表达明显高于非恶性血液病患者,尤其在急性B淋巴细胞白血病患者中高表达。     

High expression of Snail mRNA in blood from hepatocellular carcinoma patients with extra-hepatic metastasis

The presence of circulating tumor cells (CTCs) in patients with hepatocellular carcinoma (HCC) suggests metastasis to extra-hepatic organs. Snail is a key regulator of epithelial mesenchymal transition, which is closely associated with tumor metastasis. The aim of this study was to investigate the presence of CTCs and evaluate the significance of Snail mRNA levels in peripheral blood of HCC patients with and without extra-hepatic metastasis. Sixty-six consecutive patients with HCC (30 without metastasis, 36 with metastasis) were prospectively enrolled, as were 30 with liver cirrhosis and 23 healthy subjects. CTCs were isolated by FACS using Ber-EP4 and anti-CD45 antibodies, and CTC identity confirmed by immunofluorescent cytokeratin staining. Snail mRNA levels were measured by quantitative real-time PCR of blood samples. CTCs, positive for pan-cytokeratin and Snail, were isolated from five HCC patients with metastasis. The mean amount of Snail mRNA in HCC with metastasis was 18.8-fold, 26.6-fold greater than HCC without metastasis, liver cirrhosis, respectively. When compared with healthy controls, the mean level of Snail mRNA in HCC without metastasis was 10.1-fold greater (P < 0.001). In six patients showing complete remission of HCC, Snail mRNA decreased to levels similar to those of healthy controls. This study suggests the possibility that circulating Snail mRNA levels may have been associated with extra-hepatic metastasis in HCC patients.     

A five‐gene signature as a potential predictor of metastasis and survival in colorectal cancer

To understand the molecular mechanisms of metastasis and prognosis of colorectal cancer (CRC), we isolated single cell‐derived progenies (SCPs) from SW480 cells in vitro and compared their metastatic potential in an orthotopic CRC tumour model in vivo. Two groups of SCPs with the capability of high and low metastasis, respectively, were obtained. By analysing the gene expression profiles of high (SCP51), low (SCP58) metastatic SCPs, and their parental cell line (SW480/EGFP), we demonstrated that 143 genes were differentially expressed either between SCP51 and SCP58 or between SCP58 and SW480/EGFP. Gene‐annotation enrichment analysis of DAVID revealed 80 genes in the top ten clusters of the analysis (gene enrichment score > 1). Of the 80‐gene set, 32 genes are potentially involved in metastasis, as revealed by Geneclip. Five putative metastatic genes (LYN, SDCBP, MAP4K4, DKK1, and MID1) were selected for further validations. Immunohistochemical analysis in a cohort of 181 CRC clinical samples showed that the individual expression of LYN, MAP4K4, and MID1, as well as the five‐gene signature, was closely correlated with lymph node metastasis in CRC patients. More importantly, the individual expression of LYN, MAP4K4, SDCBP, and MID1, as well as the five‐gene signature, was significantly correlated with overall survival in CRC patients. Thus, our five‐gene signature may be able to predict metastasis and survival of CRC in the clinic, and opens new perspectives on the biology of CRC. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.