Integrating the immune microenvironment of prostate cancer induced bone disease

Prostate cancer (PCa) is the most frequently diagnosed cancer for men in the U.S. but does not impede patient survival until the disease is metastatic. Metastatic lesions most frequently occur in the bone, which exhibits a distinct microenvironment of immune and bone cell populations. Advances in the diagnosis and treatment of primary PCa allow for the use of tailored therapeutic approaches based on biomarkers, protein expression, and histopathology. Understanding the molecular and cellular characteristics of primary tumors has advanced therapeutic development and survival for patients with PCa. Personalized medicine has only recently emerged for the treatment of metastatic bone lesions. Tumor induced bone disease (TIBD) in patients with PCa can be classified into lytic, blastic, or mixed pathologies, with most patients exhibiting the blastic phenotype. Progress has been made in treating TIBD, but metastatic PCa has yet to be cured. Immune checkpoint inhibitors have exhibited limited responses in immunosuppressive PCa tumors, but have yet to be assessed in metastatic sites which may be susceptible to an increased inflammatory response. Recent discoveries have uncovered distinct tumor microenvironments (TMEs) of blastic and lytic bone metastases from patients with PCa, identifying actionable targets for therapeutic applications, including immune checkpoint inhibitors and targeted therapeutics. Enrichment for macrophages and T cells in patient samples suggests metastatic sites may be reappraised as immunologically targetable, despite their immunologically “cold” primary tumors. The practice of performing bone biopsies will help identify unique cellular and protein targets in the bone TME that can guide therapy decisions.     

SPECT全身骨显像对多发性骨髓瘤和前列腺癌骨转移瘤的鉴别诊断价值

目的:探究多发性骨髓瘤和前列腺癌在单光子发射计算机断层成像术(SPECT)骨显像上的区别与联系.方法:对2013年6月至2015年12月收治的SPECT图像表现为全身广泛骨质代谢活跃灶的多发性骨髓瘤和前列腺癌患者进行回顾性研究,分析两者病灶部位、数目、形态以及各自典型影像表现.结果:25例多发性骨髓瘤患者共检出327个病灶,病灶最常累及部位分别为肋骨、脊柱、骨盆、颅骨、肩关节和股骨;33例前列腺癌患者共检出851个病灶,转移病灶最常累及部位分别为脊柱、肋骨、骨盆、股骨和肩关节、胸骨、颅骨、肱骨.多发性骨髓瘤在图像上表现为多发点状或类圆形浓聚,颅骨"帽状"浓集、肋骨"串珠样"浓集是其特征性表现;前列腺癌骨显像表现为放射性核素异常浓聚,大小、形态不一,多为点状、条状、片状或不规则浓集灶,全身骨骼"超级影像"为其特征性表现.结论:SPECT骨显像对多发性骨髓瘤和前列腺癌骨转移瘤有一定的鉴别诊断价值.     

Effect of Paget's disease of bone (osteitis deformans) on the progression of prostate cancer bone metastasis

Background:Patients with prostate cancer tend to die from bone metastases. Until now, no evidence has shown that Paget's disease of bone (PDB) affects the progression of bone metastasis or overall survival of patients with prostate cancer.Methods:We searched our patient database for men who had presented with prostate cancer and PDB between June 1993 and March 2009, and identified best-matched control patients according to stage, grade, age, date of diagnosis, treatment, and race.Results:Among 1346 consecutive patients with prostate cancer diagnosed before 2008, 15 were confirmed to have comorbid PDB. Twenty-six more were identified from the institutional billing search. Including the 41 best-matched controls, our total study population was 82 patients. In the Kaplan-Meier analysis, we estimated median times from diagnosis of prostate cancer to bone metastasis to be 21.5 years for those with PDB and 9.4 years for those without PDB (P=0.044). Median overall survival times were 11.8 and 9.2 years for the two groups, respectively (P=0.008).Conclusion:For the first time, we have obtained evidence that patients with prostate cancer and PDB have delayed time to bone metastases and improved overall survival than do patients with prostate cancer alone.     

Prostate‐specific antigen screening for prostate cancer and the risk of overt metastatic disease at presentation

BACKGROUND:

The objective of this study was to estimate the total number of patients who would be expected to present with metastatic (M1) prostate cancer (PC) in the modern US population in a given year if the age‐specific and race‐specific annual incidence rates of M1 PC were the same as the rates in the era before prostate‐specific antigen (PSA) testing.

METHODS:

The authors computed the total number of men who presented with M1 PC in the Surveillance, Epidemiology, and End Results (SEER) 9 registries area in the year 2008 (the most recent SEER year) and estimated the number of cases that would be expected to occur in this area in the year 2008 in the absence of PSA testing. The expected number was computed by multiplying each age‐race–specific average annual incidence rate from the pre‐PSA era (1983‐1985) by the number of men in the corresponding age‐race category in the year 2008 and adding the products.

RESULTS:

In the year 2008, the observed and expected numbers of men presenting with M1 PC in the SEER 9 registries area were 739 and 2277, respectively, with an expected‐to‐observed ratio of 3.1 (95% confidence interval, 3.0‐3.2). If this ratio was applied to the total US population in the year 2008, then the total number of men presenting with M1 PC in that year would be equal to approximately 25,000 instead of the approximately 8000 actually observed.

CONCLUSIONS:

If the pre‐PSA era rates were present in the modern US population, then the total number of men presenting with M1 PC would be approximately 3 times greater than the number actually observed. Cancer 2012. © 2012 American Cancer Society.     

HER-2/neu genotype of breast cancer may change in bone metastasis

The genotype of breast cancer (BRC) is considered to be relatively stable during tumor progression, accordingly, determination of the estrogen receptor and HER-2/neu status is currently based on the primary tumor. However, recent data suggest that the gene expression profile of the metastatic lesion can be different compared to that of the primary BRC. Accordingly, it is possible that the HER-2/neu status is different in the metastatic lesion and the primary BRC. Since the bone is the most frequent metastatic site during the progression of BRC, we have analyzed the HER-2/neu status of 48 bone metastatic BRC cases by immunohistochemistry and fluorescent in situ hybridization, and it was possible to compare it to the primary site in 23 cases. The frequency of HER-2/neu amplification of BRC in the primary tumors was found to be 17.4% compared to 10.5% in bone metastases. Half of BRC cases with HER-2/neu amplification lost this genotype in bone metastases (4/23 versus 2/23, respectively) and even in the 2 cases where HER-2/neu amplification was retained in the metastases, the copy number was found to be decreased compared to the primary tumor. Based on our data and previous reports in the literature, we suggest to perform HER-2/neu testing both on primary tumor and samples obtained from BRC metastases, at least in case of primary tumors with HER-2/neu amplification, before introduction of HER-2/neu-targeting therapy. (Pathology Oncology Research Vol 12, No 3, 149–152)     

Cancer‐associated fibroblast‐derived Lumican promotes gastric cancer progression via the integrin β1‐FAK signaling pathway

Gastric cancer (GC) is one of the most frequent malignant tumors worldwide and is associated with high invasiveness, high metastasis and poor prognosis. Cancer‐associated fibroblasts (CAFs), residing around tumor cells in tumor stroma, are important modifiers of tumor initiation and progression. However, the molecular mechanisms by which CAF's modulate tumor development have yet not to be characterized in GC. Here we performed tissue assay analyses identifying that Lumican, an extracellular matrix protein, is highly expressed in human gastric CAFs and its expression is positively associated with depth of invasion, lymph node metastasis, TNM stage and poor survival rate of GC. Functional studies revealed that integrin β1‐FAK signaling pathways mediate the promoting effect of Lumican on GC cell proliferation, migration and invasion in vitro. In accordance with these observations, in GC cells co‐cultured with CAFs in which Lumican had been knocked down, decreased gastric tumor growth and metastasis in vivo was apparent. In summary, CAF‐derived Lumican contributes to tumorigenesis and metastasis of GC by activating the integrin β1‐FAK signaling pathway.     

Bone‐induced c‐kit expression in prostate cancer: A driver of intraosseous tumor growth

Loss of BRCA2 function stimulates prostate cancer (PCa) cell invasion and is associated with more aggressive and metastatic tumors in PCa patients. Concurrently, the receptor tyrosine kinase c‐kit is highly expressed in skeletal metastases of PCa patients and induced in PCa cells placed into the bone microenvironment in experimental models. However, the precise requirement of c‐kit for intraosseous growth of PCa and its relation to BRCA2 expression remain unexplored. Here, we show that c‐kit expression promotes migration and invasion of PCa cells. Alongside, we found that c‐kit expression in PCa cells parallels BRCA2 downregulation. Gene rescue experiments with human BRCA2 transgene in c‐kit‐transfected PCa cells resulted in reduction of c‐kit protein expression and migration and invasion, suggesting a functional significance of BRCA2 downregulation by c‐kit. The inverse association between c‐kit and BRCA2 gene expressions in PCa cells was confirmed using laser capture microdissection in experimental intraosseous tumors and bone metastases of PCa patients. Inhibition of bone‐induced c‐kit expression in PCa cells transduced with lentiviral short hairpin RNA reduced intraosseous tumor incidence and growth. Overall, our results provide evidence of a novel pathway that links bone‐induced c‐kit expression in PCa cells to BRCA2 downregulation and supports bone metastasis.     

Evaluation of the safety,pharmacokinetics and treatment effects of an ανβ3 integrin inhibitor on bone turnover and disease activity in men with hormone‐refractory prostate cancer and bone metastases

Aim: This study aimed to evaluate the safety, pharmacokinetics and treatment effects of an α_νβ₃ integrin inhibitor on bone turnover and disease activity in men with hormone‐refractory prostate cancer (HRPC) and bone metastases. Methods: A total of 21 patients with bone metastases and HRPC were randomized to receive MK‐0429 200 mg b.i.d. or 1600 mg b.i.d. for 4 weeks. Toxicity, pharmacokinetics and markers of bone turnover and tumor activity were examined. Results: Nausea was the most common adverse event: one (200‐mg group) and 11 (1600‐mg group) patients. At 4 weeks, mean AUC_{0–12 h} was 210 mmol*h (200‐mg group) and 673 mmol*h (1600‐mg group); mean C_max values were 42 mmol/L (200‐mg group) and 154 mmol/L (1600‐mg group). Urinary cross‐linked N‐telopeptides of type I collagen to creatinine ratio (uNTx), a bone turnover biomarker, showed a change from baseline of ?43.4 percent (200‐mg group) and ?34.1 percent (1600‐mg group). There was an increase in serum prostate specific antigen (PSA), a marker for disease activity, of 54.1 percent (200‐mg group) and 44.5 percent (1600‐mg group). Conclusion: MK‐0429 was generally well tolerated, with the most common side‐effect being nausea. There was some evidence of an early reduction of bone turnover, indicating a potential for clinical use in the treatment of MBD although serum PSA was unexpectedly increased during the study.     

Usefulness of bone turnover markers as predictors of mortality risk,disease progression and skeletal-related events appearance in patients with prostate cancer with bone metastases following treatment with zoledronic acid: TUGAMO study

Background:

Owing to the limited validity of clinical data on the treatment of prostate cancer (PCa) and bone metastases, biochemical markers are a promising tool for predicting survival, disease progression and skeletal-related events (SREs) in these patients. The aim of this study was to evaluate the predictive capacity of biochemical markers of bone turnover for mortality risk, disease progression and SREs in patients with PCa and bone metastases undergoing treatment with zoledronic acid (ZA).

Methods:

This was an observational, prospective and multicenter study in which ninety-eight patients were included. Patients were treated with ZA (4 mg every 4 weeks for 18 months). Data were collected at baseline and 3, 6, 9, 12, 15 and 18 months after the beginning of treatment. Serum levels of bone alkaline phosphtase (BALP), aminoterminal propeptide of procollagen type I (P1NP) and beta-isomer of carboxiterminal telopeptide of collagen I (β-CTX) were analysed at all points in the study. Data on disease progression, SREs development and survival were recorded.

Results:

Cox regression models with clinical data and bone markers showed that the levels of the three markers studied were predictive of survival time, with β-CTX being especially powerful, in which a lack of normalisation in visit 1 (3 months after the beginning of treatment) showed a 6.3-times more risk for death than in normalised patients. Levels of these markers were also predictive for SREs, although in this case BALP and P1NP proved to be better predictors. We did not find any relationship between bone markers and disease progression.

Conclusion:

In patients with PCa and bone metastases treated with ZA, β-CTX and P1NP can be considered suitable predictors for mortality risk, while BALP and P1NP are appropriate for SREs. The levels of these biomarkers 3 months after the beginning of treatment are especially important.     

TGF‐β induced PAR‐1 expression promotes tumor progression and osteoclast differentiation in giant cell tumor of bone

Although protease activated receptor‐1 (PAR‐1) has been confirmed as an oncogene in many cancers, the role of PAR‐1 in giant cell tumor (GCT) of bone has been rarely reported. The mechanism of PAR‐1 in tumor‐induced osteoclastogenesis still remains unclear. In the present study, we detected that PAR‐1 was significantly upregulated in GCT of bone compared to normal tissues, while TGF‐β was also overexpressed in GCT tissues and could promote the expression of PAR‐1 in a dose and time dependent manner. Using the luciferase reporter assay, we found that two downstreams of TGF‐β, Smad3 and Smad4, could activate the promoter of PAR‐1, which might explain the mechanism of TGF‐β induced PAR‐1 expression. Meanwhile, PAR‐1 was also overexpressed in microvesicles from stromal cells of GCT (GCTSCs), and might be transported from GCTSCs to monocytes through microvesicles. In addition, knockout of PAR‐1 by TALENs in GCTSCs inhibited tumor growth, angiogenesis and osteoclastogenesis in GCT in vitro. Using the chick CAM models, we further showed that inhibition of PAR‐1 suppressed tumor growth and giant cell formation in vivo. Using microarray assay, we detected a number of genes involved in osteoclastogenesis as the possible downstreams of PAR‐1, which may partly explain the mechanism of PAR‐1 in GCT. In brief, for the first time, these results reveal an upstream regulatory role of TGF‐β in PAR‐1 expression, and PAR‐1 expression promotes tumor growth, angiogenesis and osteoclast differentiation in GCT of bone. Hence, PAR‐1 represents a novel potential therapeutic target for GCT of bone.     

Micro‐RNA‐21 regulates TGF‐β‐induced myofibroblast differentiation by targeting PDCD4 in tumor‐stroma interaction

Transforming growth factor‐β1 (TGF‐β1) induces stromal fibroblast‐to‐myofibroblast transdifferentiation in the tumor‐stroma interactive microenvironment via modulation of multiple phenotypic and functional genes, which plays a critical role in tumor progression. Up to now, the involvement of micro‐RNAs (miRNAs) and their roles in TGF‐β1‐induced myofibroblast differentiation in tumor‐stroma interaction are unclear. Using quantitative real‐time RT‐PCR, we demonstrated that the expression of micro‐RNA‐21 (miR‐21) was upregulated in activated fibroblasts after treatment with TGF‐β1 or conditioned medium from cancer cells. To determine the potential roles of miR‐21 in TGF‐β1‐mediated gene regulation during myofibroblast conversion, we showed that miR‐21 expression was downregulated by miR‐21 inhibitor and upregulated by miR‐21 mimic. Interestingly, downregulation of miR‐21 with the inhibitor effectively inhibited TGF‐β1‐induced myofibroblast differentiation while upregulation of miR‐21 with a mimic significantly promoted myofibroblast differentiation. We further demonstrated that MiR‐21 directly targeted and downregulated programmed cell death 4 (PDCD4) gene, which in turn acted as a negative regulator of several phenotypic and functional genes of myofibroblasts. Taken together, these results suggested that miR‐21 participated in TGF‐β1‐induced myofibroblast transdifferentiation in cancer stroma by targeting PDCD4.     

Economic burden of metastatic bone disease in the U.S

BACKGROUND: Previous research has documented the prevalence of primary bone cancer; however, there are few data available regarding the impact of metastatic bone disease (MBD) on national expenditure. In this study, the authors quantified the prevalence and direct medical care costs of patients with MBD and the resulting cost impact on U.S. oncology expenditure. METHODS: Anonymous, patient-level data on health care utilization and cost were obtained from the Thomson Medstat MarketScan research databases. In total, 396,200 patients who were diagnosed with cancer between 2000 and 2004 were selected for the study. Patients with MBD were matched subsequently to non-MBD controls. A 2-part linear regression model was used to compare cases with controls to quantify the incremental cost associated with the disease. RESULTS: Cancer prevalence in the U.S. during the study period was estimated at 4,861,987 cases annually, and 5.3% (n=256,137) of those patients had MBD. Rates of MBD were highest in patients with multiple myeloma (28.8%) and lung cancer (15.6%). The mean direct medical cost for all cancers combined was $75,329 for patients with MBD and $31,382 for controls. Regression-adjusted, incremental costs were $44,442 (P<.001) across all cancer types. The incremental cost was highest for patients with multiple myeloma ($63,455) and lowest for patients with lung cancer ($24,946). CONCLUSIONS: The national cost burden for patients with MBD was estimated at $12.6 billion, which is 17% of the $74 billion in total direct medical cost estimated by the National Institutes of Health, suggesting that MBD is a significant driver of overall oncology cost.