Nuclear localization of parathyroid hormone-related peptide confers resistance to anoikis in prostate cancer cells

An anoikis-related gene signature for prediction of the prognosis in prostate cancer

Purpose

This study presents a novel approach to predict postoperative biochemical recurrence (BCR) in prostate cancer (PCa) patients which involves constructing a signature based on anoikis-related genes (ARGs).

Methods

In this study, we utilised data from TCGA-PARD and GEO databases to identify specific ARGs in prostate cancer. We established a signature of these ARGs using Cox regression analysis and evaluated their clinical predictive efficacy and immune-related status through various methods such as Kaplan-Meier survival analysis, subject work characteristics analysis, and CIBERSORT method. Our findings suggest that these ARGs may have potential as biomarkers for prostate cancer prognosis and treatment. To investigate the biological pathways of genes associated with anoikis, we utilised GSVA, GO, and KEGG. The expression of ARGs was confirmed by the HPA database. Furthermore, we conducted PPI analysis to identify the core network of ARGs in PCa.

Results

Based on analysis of the TCGA database, a set of eight ARGs were identified as prognostic signature genes for prostate cancer. The reliability and validity of this signature were well verified in both the TCGA and GEO codifications. Using this signature, patients were classified into two groups based on their risk for developing BCR. There was a significant difference in BCR-free time between the high and low risk groups (P < 0.05).This signature serves as a dependable and unbiased prognostic factor for predicting biochemical recurrence (BCR) in prostate cancer (PCa) patients. It outperforms clinicopathological characteristics in terms of accuracy and reliability. PLK1 may play a potential regulatory role as a core gene in the development of prostate cancer.

Conclusion

This signature suggests the potential role of ARGs in the development and progression of PCa and can effectively predict the risk of BCR in PCa patients after surgery. It also provides a basis for further research into the mechanism of ARGs in PCa and for the clinical management of patients with PCa.

Integrated bioinformatics analysis of differentially expressed genes in the temporomandibular joint internal derangement

OBJECTIVES

This study aimed to identify significant mechanisms and potential treatments for temporomandibular joint internal derangement (TMJD) through integrated bioinformatics analysis.

MATERIALS AND METHODS

Gene expression data sets (GSE66864) from the Gene Expression Omnibus (GEO) database were downloaded. Differentially expressed genes (DEGs) were identified both in the treatment groups and in controls by R packages. Network analysis of protein-protein interaction (PPI) and Human Protein Atlas was used to explore DEGs' potential function. DGIdb database was utilized to gain potential drug targets.

RESULTS

In conclusion, 126 DEGs were selected for TMJD through bioinformatics analysis. Both GO and Kyoto Encyclopedia of Genes and Genomes analyses combined showed the pathways involved in TMJD. A PPI network was constructed to select the top 10 hub genes, of which five hub genes were chosen for further investigation. Moreover, the microenvironment of immune cells related to hub genes was evaluated by R packages. Macrophages play an important role in inflammation and oral-related tumors. The Human Protein Atlas analysis indicated that the five hub genes are highly related to head and neck cancer. Finally, eight potential drugs were selected for two genes using the DGIdb database.

CONCLUSION

Our integrated bioinformatics analysis identified DEGs in TMJD and provided potential ideas for further research and treatment approaches. However, experimental validation of the hub genes and potential drug targets is still needed. The key mechanisms of the identified genes and their potential roles as biomarkers or drug targets in TMJD require further investigation.

Parathyroid hormone-related peptide and parathyroid hormone-related peptide receptor type 1 in locally advanced laryngeal cancer as prognostic indicators of relapse and survival

Background

Parathyroid hormone-related peptide (PTHrP) overexpression and poor patient outcome have been reported for many human tumors, but no studies are available in laryngeal cancer. Therefore, we studied the expression of PTHrP and its receptor, parathyroid hormone-related peptide receptor type 1 (PTH1R), in primary locally advanced laryngeal squamous cell carcinomas (LALSCC) also in relation to the clinical outcome of patients.

Methods

We conducted a retrospective exploratory study, using immunohistochemistry, on PTHrP, PTH1R and HER1 expressions in LALSCC of 66 patients treated with bio-radiotherapy with cetuximab.

Results

The expressions of PTHrP and PTH1R in LALSCC were associated with the degree of tumor differentiation (p = 0.01 and 0.04, respectively). Poorly differentiated tumors, with worse prognosis, expressed PTHrP at nuclear level and were PTH1R negative. PTHrP and PTH1R were expressed at cytoplasmic level in normal larynx epithelium and more differentiated laryngeal cancer cells, suggesting an autocrine/paracrine role of PTHrP in squamous cell differentiation of well differentiated tumors with good prognosis. Eighty-one percent HER1 positive tumors expressed PTHrP (p < 0.0001), mainly at nuclear level, consistent with the known up-regulation of PTHrP gene by HER1 signaling. In multivariable analyses, patients with PTHrP positive tumors had a higher relative risk of relapse (HR = 5.49; CI 95% = 1.62–22.24; p = 0.006) and survival (HR = 8.21; CI 95% = 1.19–105.00; p = 0.031) while those with PTH1R positive tumors showed a lower relative risk of relapse (HR = 0.18; CI 95% = 0.04–0.62; p = 0.002) and survival (HR = 0.18; CI 95% = 0.04–0.91; p = 0.029).

Conclusions

In LALSCC nuclear PTHrP and absence of PTH1R expressions could be useful in predicting response and/or resistance to cetuximab in combined therapies, contributing to an aggressive behavior of tumor cells downstream to HER1.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09748-1.

Parathyroid hormone-related protein (PTHrP)-dependent modulation of gene expression signatures in cancer cells

PTHrP is encoded by PTHLH gene which can generate by alternative promoter usage and splicing mechanisms at least three mature peptides of 139, 141 and 173 amino acids with distinct carboxy terminus. PTHrP may undergo proteolytic processing into smaller bioactive forms, comprising an amino terminus peptide, which is the mediator of the "classical" PTH-like effect, as well as midregion and carboxy terminus peptides that act as multifaceted critical regulator of proliferation, differentiation and apoptosis via the reprogramming of gene expression in normal and neoplastic cells. Moreover, a nuclear/nucleolar localization signal sequence is present in the [87-107] domain allowing PTHrP nuclear import and "intracrine" effect additional to the autocrine/paracrine one. Within the large number of data available in the literature on PTHrP bioactivities, the goal of this chapter is to pick up selected studies that report the detection of molecular signatures of cancer cell exposure to PTHrP, either as full-length protein or discrete peptides, demonstrated by individual gene or whole genome expression profiling, briefly recapitulating the biological implications associated with the specific gene activation or silencing.

PTHLH Predicts the Prognosis of Patients with Oral Leukoplakia

Background

Oral leukoplakia is the most common oral mucosal disease. A proportion of such cases can progress to oral squamous cell carcinoma (OSCC). The mechanism of oral leukoplakia malignant transformation is still unclear. In this study, we analyzed the expression of parathyroid hormone-like hormone (PTHLH) in oral leukoplakia and the effect on prognosis, so as to find reliable molecular markers that can predict oral leukoplakia malignant transformation.

Methods

We measured PTHrP which is coded by PTHLH in oral leukoplakia tissues of 79 cases (30 cases progressed to OSCC and 49 did not) and analyzed the clinical outcomes. Then, PTHLH expression was reduced using lentivirus-mediated small hairpin RNA (shRNA) interference to determine the biological role of PTHLH in DOK cells.

Results

PTHrP was found to be highly expressed in 38% of tissues of oral leukoplakia. There was weak or no PTHrP expression in 25 patients, moderate expression in 24 patients, and strong in 30 patients with oral leukoplakia. The expression level was associated with the degree of atypical hyperplasia and poor prognosis. The cell proliferation, invasion, migration, cell cloning, and cell cycle were affected after reducing PTHLH expression.

Conclusion

Our data suggest that either PTHLH or PTHrP plays a key role in the malignant transformation of oral leukoplakia and might be a reliable biomarker for predicting the carcinogenesis of oral leukoplakia.

PTHrP treatment of colon cancer cells promotes tumor associated-angiogenesis by the effect of VEGF

We showed that Parathyroid Hormone-related Peptide (PTHrP) induces proliferation, migration, survival and chemoresistance via MAPKs and PI3K/AKT pathways in colorectal cancer (CRC) cells. The objective of this study was to investigate if PTHrP is also involved in tumor angiogenesis. PTHrP increased VEGF expression and the number of structures with characteristics of neoformed vessels in xenografts tumor. Also, PTHrP increased mRNA levels of VEGF, HIF-1α and MMP-9 via ERK1/2 and PI3K/Akt pathways in Caco-2 and HCT116 cells. Tumor conditioned media (TCMs) from both cell lines treated with PTHrP increases the number of cells, the migration and the tube formation in the endothelial HMEC-1 cells, whereas the neutralizing antibody against VEGF diminished this response. In contrast, PTHrP by direct treatment only increased ERK1/2 phosphorylation and the HMEC-1 cells number. These results provide the first evidence related to the mode of action of PTHrP that leads to its proangiogenic effects in the CRC.

Interaction between Tumor-Associated Dendritic Cells and Colon Cancer Cells Contributes to Tumor Progression via CXCL1

Crosstalk of a tumor with its microenvironment is a critical factor contributing to cancer development. This study investigates the soluble factors released by tumor-associated dendritic cells (TADCs) responsible for increasing cancer stem cell (CSC) properties, cell mobility, and epithelial-to-mesenchymal transition (EMT). Dendritic cells (DCs) of colon cancer patients were collected for phenotype and CXCL1 expression by flow cytometry and Luminex assays. The transcriptome of CXCL1-treated cancer cells was established by next generation sequencing. Inflammatory chemokine CXCL1, present in large amounts in DCs isolated from colon cancer patients, and SW620-conditioned TADCs, enhance CSC characteristics in cancer, supported by enhanced anchorage-independent growth, CD133 expression and aldehyde dehydrogenase activity. Additionally, CXCL1 increases the metastatic ability of a cancer by enhancing cell migration, matrix metalloproteinase-7 expression and EMT. The enhanced CXCL1 expression in DCs is also noted in mice transplanted with colon cancer cells. Transcriptome analysis of CXCL1-treated SW620 cells indicates that CXCL1 increases potential oncogene expression in colon cancer, including PTHLH, TYRP1, FOXO1, TCF4 and ZNF880. Concurrently, CXCL1 displays a specific microRNA (miR) upregulated by the prototypical colon cancer onco-miR miR-105. Analysis of publicly available data reveals CXCL1-driven oncogenes and miR-105 have a negative prognostic impact on the outcome of colon cancer. This study indicates a new mechanism by which the colon cancer milieu exploits DC plasticity to support cancer progression.

Survival analysis of multiple peptide vaccination for the selection of correlated peptides in urological cancers

Peptide‐based cancer vaccines are able to induce strong immune responses, but their clinical results are unsatisfactory. To determine clinically correlated peptides, we analyzed survival data from urological cancer patients treated by personalized peptide vaccination (PPV), in which different multiple peptides were used for individual patients based on human leukocyte antigen (HLA) type and pre‐existing immunity. Survival data were obtained from a database of 265 urological cancer patients treated in 5 clinical PPV trials comprising 154 patients with castration‐resistant prostate cancer (CRPC) and 111 patients with advanced urothelial cancer (UC). Expression of tumor‐associated antigens (TAA) was evaluated in 10 prostate cancer tissues, 4 metastatic lymph nodes from prostate cancer, and 10 UC tissues using immunohistochemical staining. Clinical efficacy of individual peptides for overall survival was evaluated by the Cox proportional hazards regression model. All TAA coding candidate peptides used in PPV treatment were expressed in tumor cells from prostate cancer and UC samples except for p56Lck in both, and prostate‐specific antigen (PSA), prostatic acid phosphatase (PAP) and prostate‐specific membrane antigen (PSMA) in the UC samples. Patients with the following peptides had a significantly longer survival than patients without the peptides (hazard ratio <1.0, 95% confidence intervals <1.0 and P < .05): SART3‐109, PTHrP‐102, HNPRL‐140, SART3‐302 and Lck‐90 in CRPC patients, and EGF‐R‐800, Lck‐486, PSMA‐624, CypB‐129 and SART3‐734 in advanced UC patients, respectively. Correlated peptides selected using both survival data and pre‐existing immunity for PPV treatment may enhance the clinical benefits for urological cancer patients.

Fatty Acids and Calcium Regulation in Prostate Cancer

Prostate cancer is a widespread malignancy characterized by a comparative ease of primary diagnosis and difficulty in choosing the individualized course of treatment. Management of prostate cancer would benefit from a clearer understanding of the molecular mechanisms behind the transition to the lethal, late-stage forms of the disease, which could potentially yield new biomarkers for differential prognosis and treatment prioritization in addition to possible new therapeutic targets. Epidemiological research has uncovered a significant correlation of prostate cancer incidence and progression with the intake (and often co-intake) of fatty acids and calcium. Additionally, there is evidence of the impact of these nutrients on intracellular signaling, including the mechanisms mediated by the calcium ion as a second messenger. The present review surveys the recent literature on the molecular mechanisms associated with the critical steps in the prostate cancer progression, with special attention paid to the regulation of these processes by fatty acids and calcium homeostasis. Testable hypotheses are put forward that integrate some of the recent results in a more unified picture of these phenomena at the interface of cell signaling and metabolism.

GSEH: A Novel Approach to Select Prostate Cancer-Associated Genes Using Gene Expression Heterogeneity

When a gene shows varying levels of expression among normal people but similar levels in disease patients or shows similar levels of expression among normal people but different levels in disease patients, we can assume that the gene is associated with the disease. By utilizing this gene expression heterogeneity, we can obtain additional information that abets discovery of disease-associated genes. In this study, we used collaborative filtering to calculate the degree of gene expression heterogeneity between classes and then scored the genes on the basis of the degree of gene expression heterogeneity to find "differentially predicted" genes. Through the proposed method, we discovered more prostate cancer-associated genes than 10 comparable methods. The genes prioritized by the proposed method are potentially significant to biological processes of a disease and can provide insight into them.

Effect of PI3K/Akt Signaling Pathway on the Process of Prostate Cancer Metastasis to Bone

We sought to study the effects of PI3K/Akt pathway and its downstream substrate NF-κB on prostate cancer bone metastatic process. Expression level of active p-Akt in PC3 cells was upregulated by transient expression with constitutively active plasmid CA-Akt or, alternatively, suppressed by dominant negative construct DN-Akt. NF-κB activity was determined by luciferase reporter assays. mRNA and protein expressions of receptor activator of NF-κB ligand (RANKL), parathyroid hormone-related protein (PTHrP), and bone morphogenetic protein 2 (BMP-2) were evaluated using RT-PCR and Western blotting. The effect of cross-talk between PC3 and SaOS2 cells on cell proliferation was analyzed using a co-culture system. Stimulation of p-Akt promoted NF-κB activity, and led to an increase in mRNA and protein expressions of RANKL, PTHrP, and BMP-2 in PC3 PCa cells through NF-κB. Co-culturing PC3 and SaOS2 cells significantly increased the expression of p-Akt and the activity of NF-κB, and promoted proliferation of both PC3 and SaOS2 cells. Increasing expression levels of p-Akt by transfection with CA-Akt led to further increase in cells proliferation, whereas NF-κB inhibitor PDTC partially blocked this effect. PI3K/Akt pathway stimulates the expressions of RANKL, PTHrP, and BMP-2 partly through NF-κB, suggesting its importance for bone metastasis of prostate carcinoma. Interaction of prostate cancer cells with bone cells has a stimulatory effect on cell proliferation.

Osteoblasts Are the Centerpiece of the Metastatic Bone Microenvironment

The tumor microenvironment is comprised of diverse stromal cell populations in addition to tumor cells. Increasing evidence now clearly supports the role of microenvironment stromal cells in tumor progression and metastasis, yet the regulatory mechanisms and interactions among tumor and stromal cells remain to be elucidated. Bone metastasis is the major problem in many types of human malignancies including prostate, breast and lung cancers, and the biological basis of bone metastasis let alone curative approaches are largely undetermined. Among the many types of stromal cells in bone, osteoblasts are shown to be an important player. In this regard, osteoblasts are a key target cell type in the development of bone metastasis, but there are currently no drugs or therapeutic approaches are available that specifically target osteoblasts. This review paper summarizes the current knowledge on osteoblasts in the metastatic tumor microenvironment, aiming to provide clues and directions for future research endeavor.

Intrinsic cellular signaling mechanisms determine the sensitivity of cancer cells to virus-induced apoptosis

Cancer cells of epithelial and mesenchymal phenotypes exhibit different sensitivities to apoptosis stimuli, but the mechanisms underlying this phenomenon remain partly understood. We constructed a novel recombinant adenovirus expressing Ad12 E1A (Ad-E1A12) that can strongly induce apoptosis. Ad-E1A12 infection of epithelial cancer cells displayed dramatic detachment and apoptosis, whereas cancer cells of mesenchymal phenotypes with metastatic propensity were markedly more resistant to this virus. Notably, forced detachment of epithelial cells did not further sensitize them to Ad-E1A12-induced apoptosis, suggesting that cell detachment is a consequence rather than the cause of Ad-E1A12-induced apoptosis. Ad-E1A12 increased phosphorylation of AKT1 and ribosomal protein S6 through independent mechanisms in different cell types. Ad-E1A12–induced AKT1 phosphorylation was PI3K-dependent in epithelial cancer cells, and mTOR-dependent in mesenchymal cancer cells. Epithelial cancer cells upon Ad-E1A12-induced detachment could not sustain AKT activation due to AKT1 degradation, but AKT1 activation was maintained in mesenchymal cancer cells. Expression of epithelial cell-restricted miR-200 family in mesenchymal cells limited mTOR signaling and sensitized them to Ad-E1A12-induced cell killing. Thus, epithelial cancer cells rely on the canonical PI3K-AKT signaling pathway for survival, while mesenchymal cancer cells deploy the PI3K-independent mTORC2-AKT axis in response to strong death stimuli.

Induction of thermal and mechanical hypersensitivity by parathyroid hormone-related peptide through upregulation of TRPV1 function and trafficking

The neurobiological mechanisms underlying chronic pain associated with cancers are not well understood. It has been hypothesized that factors specifically elevated in the tumor microenvironment sensitize adjacent nociceptive afferents. We show that parathyroid hormone-related peptide (PTHrP), which is found at elevated levels in the tumor microenvironment of advanced breast and prostate cancers, is a critical modulator of sensory neurons. Intraplantar injection of PTHrP led to the development of thermal and mechanical hypersensitivity in both male and female mice, which were absent in mice lacking functional transient receptor potential vanilloid-1 (TRPV1). The PTHrP treatment of cultured mouse sensory neurons enhanced action potential firing, and increased TRPV1 activation, which was dependent on protein kinase C (PKC) activity. Parathyroid hormone-related peptide induced robust potentiation of TRPV1 activation and enhancement of neuronal firing at mild acidic pH that is relevant to acidic tumor microenvironment. We also observed an increase in plasma membrane TRPV1 protein levels after exposure to PTHrP, leading to upregulation in the proportion of TRPV1-responsive neurons, which was dependent on the activity of PKC and Src kinases. Furthermore, co-injection of PKC or Src inhibitors attenuated PTHrP-induced thermal but not mechanical hypersensitivity. Altogether, our results suggest that PTHrP and mild acidic conditions could induce constitutive pathological activation of sensory neurons through upregulation of TRPV1 function and trafficking, which could serve as a mechanism for peripheral sensitization of nociceptive afferents in the tumor microenvironment.

PTHrP Nuclear Localization and Carboxyl Terminus Sequences Modulate Dental and Mandibular Development in Part via the Action of p27

To determine whether the action of the PTHrP nuclear localization sequence and C terminus is mediated through p27 in modulating dental and mandibular development, compound mutant mice, which are homozygous for both p27 deletion and the PTHrP1-84 knock-in mutation (p27(-/-)Pthrp(KI/KI)), were generated. Their teeth and mandibular phenotypes were compared with those of p27(-/-), Pthrp(KI/KI), and wild-type mice. At 2 weeks of age, the mandibular mineral density, alveolar bone volume, osteoblast numbers, and dental volume, dentin sialoprotein-immunopositive areas in the first molar were increased significantly in p27(-/-) mice and decreased dramatically in both Pthrp(KI/KI) and p27(-/-) Pthrp(KI/KI) mice compared with wild-type mice; however, these parameters were partly rescued in p27(-/-) Pthrp(KI/KI) mice compared with Pthrp(KI/KI) mice. These data demonstrate that the deletion of p27 in Pthrp(KI/KI) mice can partially rescue defects in dental and mandibular development. Furthermore, we found that deletion of p27 in Pthrp(KI/KI) mice partially corrected the dental and mandibular phenotype by modulating cell cyclin-regulating molecules and antioxidant enzymes. This study therefore indicates that the p27 pathway may function downstream in the action of PTHrP nuclear localization sequence to regulate dental and mandibular development.

Inhibition of cyclic AMP response element-directed transcription by decoy oligonucleotides enhances tumor-specific radiosensitivity

The radiation stress induces cytotoxic responses of cell death as well as cytoprotective responses of cell survival. Understanding exact cellular mechanism and signal transduction pathways is important in improving cancer radiotherapy. Increasing evidence suggests that cyclic AMP response element binding protein (CREB)/activating transcription factor (ATF) family proteins act as a survival factor and a signaling molecule in response to stress. We postulated that CREB inhibition via CRE decoy oligonucleotide increases tumor cell sensitization to γ-irradiation-induced cytotoxic stress. In the present study, we demonstrate that CREB phosphorylation and CREB DNA-protein complex formation increased in time- and radiation dose-dependent manners, while there was no significant change in total protein level of CREB. In addition, CREB was phosphorylated in response to γ-irradiation through p38 MAPK pathway. Further investigation revealed that CREB blockade by decoy oligonucleotides functionally inhibited transactivation of CREB, and significantly increased radiosensitivity of multiple human cancer cell lines including TP53- and/or RB-mutated cells with minimal effects on normal cells. We also demonstrate that tumor cells ectopically expressing dominant negative mutant CREB (KCREB) and the cells treated with p38 MAPK inhibitors were more sensitive to γ-irradiation than wild type parental cells or control-treated cells. Taken together, we conclude that CREB protects tumor cells from γ-irradiation, and combination of CREB inhibition plus ionizing radiation will be a promising radiotherapeutic approach.

Phase I trial of a cancer vaccine consisting of 20 mixed peptides in patients with castration-resistant prostate cancer: dose-related immune boosting and suppression

The heterogeneity expression of tumor-associated antigens (TAA) and variability of human T cell repertoire suggest that effective cancer vaccine requires induction of a wide breadth of cytotoxic T lymphocyte (CTL) specificities. This can be achieved with vaccines targeting multiple TAA. We evaluated the safety and immune dynamics of a cancer vaccine consisting of 20 mixed peptides (KRM-20) designed to induce CTLs against 12 different TAA in patients with castration-resistant prostate cancer (CRPC). Patients received each of three different randomly assigned doses of KRM-20 (6, 20, or 60 mg) once a week for 6 weeks. KRM-20 was applicable for patients with positive human leukocyte antigen (HLA) A2, A3, A11, A24, A26, A31 or A33 alleles, which cover the majority of the global population. To evaluate the minimum immunological effective dose (MIED), peptide-specific CTL and immunoglobulin G (IgG) responses, and immune suppressive subsets were evaluated during the vaccination. Total of 17 patients was enrolled. No serious adverse drug reactions were encountered. The MIED of KRM-20 in CTL or IgG response calculated by logistic regression model was set as 16 or 1.6 mg, respectively. The frequency of immune suppressive subsets was fewer in the 20 mg cohort than that in 6 or 60 mg cohort. Clinical responses determined by prostate-specific antigen levels were two partial responses (from the 20 mg cohort), five no changes and ten progressive diseases. Twenty milligrams of KRM-20 could be recommended for further studies because of the safety and ability to augment CTL activity.

Parathyroid hormone-related protein serves as a prognostic indicator in oral squamous cell carcinoma

BACKGROUND

In our previous study, parathyroid hormone-like hormone (PTHLH) which encodes parathyroid hormone-related protein (PTHrP) was revealed to be up-regulated in oral squamous cell carcinoma (OSCC) compared with paired apparently normal surgical margins using microarray method. However, the function and prognostic indicators of PTHLH/PTHrP in OSCC remain obscure.

METHODS

The mRNA levels of PTHLH and its protein levels were investigated in 9 OSCC cell lines and in 36 paired OSCC specimens by real-time PCR and western blotting. The biological function of PTHLH/PTHrP was investigated using small interfering RNA (siRNA) in 3 OSCC cell lines, and immunohistochemistry was used to estimate the prognostic value of PTHrP in 101 patients with head and neck squamous cell carcinoma (HNSCC), including OSCC and oropharyngeal squamous cell carcinoma. Cell cycle was tested by flow cytometry and cell cycle related genes were investigated by western blotting and immunocytochemistry assay.

RESULTS

This study showed that the mRNA and protein levels of PTHLH in 9 OSCC cell lines were much higher than that in normal epithelial cells (P < 0.0001). In 36 paired OSCC tissues, PTHLH mRNA expressions were found higher in 32 OSCC tissues than that of paired apparently normal surgical margins (P = 0.0001). The results revealed that the down-regulation of PTHLH/PTHrP by siRNAs could reduce cell proliferation and inhibit plate and soft agar colony formation as well as affect the cell cycle of OSCC cells. The key proteins related to the cell cycle were changed by anti-PTHLH siRNA. The results showed that cyclin D1 and CDK4 expressions were significantly reduced in the cells transfected with anti-PTHLH siRNA. On the other hand, the expression of p21 was increased. The results also showed that high PTHrP level was associated with poor pathologic differentiation (P = 0.0001) and poor prognosis (P = 0.0003) in patients with HNSCC.

CONCLUSIONS

This study suggests that PTHLH/PTHrP is up-regulated in OSCCs. Therefore, PTHLH/PTHrP could play a role in the pathogenesis of OSCC by affecting cell proliferation and cell cycle, and the protein levels of PTHrP might serve as a prognostic indicator for evaluating patients with HNSCCs.

Deletion of the nuclear localization sequences and C-terminus of PTHrP impairs embryonic mammary development but also inhibits PTHrP production

Parathyroid hormone-related protein (PTHrP) can be secreted from cells and interact with its receptor, the Type 1 PTH/PTHrP Receptor (PTHR1) in an autocrine, paracrine or endocrine fashion. PTHrP can also remain inside cells and be transported into the nucleus, where its functions are unclear, although recent experiments suggest that it may broadly regulate cell survival and senescence. Disruption of either the PTHrP or PTHR1 gene results in many abnormalities including a failure of embryonic mammary gland development in mice and in humans. In order to examine the potential functions of nuclear PTHrP in the breast, we examined mammary gland development in PTHrP (1-84) knock-in mice, which express a mutant form of PTHrP that lacks the C-terminus and nuclear localization signals and which can be secreted but cannot enter the nucleus. Interestingly, we found that PTHrP (1-84) knock-in mice had defects in mammary mesenchyme differentiation and mammary duct outgrowth that were nearly identical to those previously described in PTHrP-/- and PTHR1-/- mice. However, the mammary buds in PTHrP (1-84) knock-in mice had severe reductions in mutant PTHrP mRNA levels, suggesting that the developmental defects were due to insufficient production of PTHrP by mammary epithelial cells and not loss of PTHrP nuclear function. Examination of the effects of nuclear PTHrP in the mammary gland in vivo will require the development of alternative animal models.

PTHrP produced by myeloma plasma cells regulates their survival and pro-osteoclast activity for bone disease progression

To promote their survival and progression in the skeleton, osteotropic malignancies of breast, lung, and prostate produce parathyroid hormone-related protein (PTHrP), which induces hypercalcemia. PTHrP serum elevations have also been described in multiple myeloma (MM), although their role is not well defined. When we investigated MM cells from patients and cell lines, we found that PTHrP and its receptor (PTH-R1) are highly expressed, and that PTHrP is secreted both as a full-length molecule and as small subunits. Among these subunits, the mid-region, including the nuclear localization sequence (NLS), exerted a proliferative effect because it was accumulated in nuclei of MM cells surviving in starvation conditions. This was confirmed by increased transcription of several genes enrolled in proliferation and apoptosis control. PTHrP was also found to stimulate PTH-R1 in MM cells. PTH-R1's selective activation by the full-length PTHrP molecule or the NH2 -terminal fragment resulted in a significant increase of intracellular Ca(2+) influx, cyclic adenosine monophosphate (cAMP) content, and expression of receptor activator of NF-κB ligand (RANKL) and monocyte chemoattractant protein-1 (MCP-1). Our data definitely clarify the role of PTHrP in MM. The PTHrP peptide is functionally secreted by malignant plasma cells and contributes to MM tumor biology and progression, both by intracrine maintenance of cell proliferation in stress conditions and by autocrine or paracrine stimulation of PTH-R1, which in turn reinforces the production of osteoclastogenic factors. © 2014 American Society for Bone and Mineral Research.

Parathyroid hormone-related protein drives a CD11b+Gr1+ cell-mediated positive feedback loop to support prostate cancer growth

In the tumor microenvironment, CD11b(+)Gr1(+) bone marrow-derived cells are a predominant source of protumorigenic factors such as matrix metalloproteinases (MMP), but how distal tumors regulate these cells in the bone marrow is unclear. Here we addressed the hypothesis that the parathyroid hormone-related protein (PTHrP) potentiates CD11b(+)Gr1(+) cells in the bone marrow of prostate tumor hosts. In two xenograft models of prostate cancer, levels of tumor-derived PTHrP correlated with CD11b(+)Gr1(+) cell recruitment and microvessel density in the tumor tissue, with evidence for mediation of CD11b(+)Gr1(+) cell-derived MMP-9 but not tumor-derived VEGF-A. CD11b(+)Gr1(+) cells isolated from mice with PTHrP-overexpressing tumors exhibited relatively increased proangiogenic potential, suggesting that prostate tumor-derived PTHrP potentiates this activity of CD11b(+)Gr1(+) cells. Administration of neutralizing PTHrP monoclonal antibody reduced CD11b(+)Gr1(+) cells and MMP-9 in the tumors. Mechanistic investigations in vivo revealed that PTHrP elevated Y418 phosphorylation levels in Src family kinases in CD11b(+)Gr1(+) cells via osteoblast-derived interleukin-6 and VEGF-A, thereby upregulating MMP-9. Taken together, our results showed that prostate cancer-derived PTHrP acts in the bone marrow to potentiate CD11b(+)Gr1(+) cells, which are recruited to tumor tissue where they contribute to tumor angiogenesis and growth.

PTH prevents the adverse effects of focal radiation on bone architecture in young rats

Radiation therapy is a common treatment regimen for cancer patients. However, its adverse effects on the neighboring bone could lead to fractures with a great impact on quality of life. The underlying mechanism is still elusive and there is no preventive or curative solution for this bone loss. Parathyroid hormone (PTH) is a current therapy for osteoporosis that has potent anabolic effects on bone. In this study, we found that focal radiation from frequent scans of the right tibiae in 1-month-old rats by micro-computed tomography severely decreased trabecular bone mass and deteriorated bone structure. Interestingly, PTH daily injections remarkably improved trabecular bone in the radiated tibiae with increases in trabecular number, thickness, connectivity, structure model index and stiffness, and a decrease in trabecular separation. Histomorphometric analysis revealed that radiation mainly decreased the number of osteoblasts and impaired their mineralization activity but had little effects on osteoclasts. PTH reversed these adverse effects and greatly increased bone formation to a similar level in both radiated and non-radiated bones. Furthermore, PTH protects bone marrow mesenchymal stem cells from radiation-induced damage, including a decrease in number and an increase in adipogenic differentiation. While radiation generated the same amount of free radicals in the bone marrow of vehicle-treated and PTH-treated animals, the percentage of apoptotic bone marrow cells was significantly attenuated in the PTH group. Taken together, our data demonstrate a radioprotective effect of PTH on bone structure and bone marrow and shed new light on a possible clinical application of anabolic treatment in radiotherapy.

Parathyroid hormone-related protein (PTHrP) modulates adhesion, migration and invasion in bone tumor cells

Parathyroid-hormone-related protein (PTHrP) has been shown to be an important factor in osteolysis in the setting of metastatic carcinoma to the bone. However, PTHrP may also be central in the setting of primary bone tumors. Giant cell tumor of bone (GCT) is an aggressive osteolytic bone tumor characterized by osteoclast-like giant cells that are recruited by osteoblast-like stromal cells. The stromal cells of GCT are well established as the only neoplastic element of the tumor, and we have previously shown that PTHrP is highly expressed by these cells both in vitro and in vivo. We have also found that the stromal cells exposed to a monoclonal antibody to PTHrP exhibited rapid plate detachment and quickly died in vitro. Therefore, PTHrP may serve in an autocrine manner to increase cell proliferation and promote invasive properties in GCT. The purpose of this study was to use transcriptomic microarrays and functional assays to examine the effects of PTHrP neutralization on cell adhesion, migration and invasion. Microarray and proteomics data identified genes that were differentially expressed in GCT stromal cells under various PTHrP treatment conditions. Treatment of GCT stromal cells with anti-PTHrP antibodies showed a change in the expression of 13 genes from the integrin family relative to the IgG control. Neutralization of PTHrP reduced cell migration and invasion as evidenced by functional assays. Adhesion and anoikis assays demonstrated that although PTHrP neutralization inhibits cell adhesion properties, cell detachment related to PTHrP neutralization did not result in associated cell death, as expected in mesenchymal stromal cells. Based on the data presented herein, we conclude that PTHrP excreted by GCT stromal cells increases bone tumor cell local invasiveness and migration.

A novel canine model for prostate cancer

BACKGROUND

No existing animal model fully recapitulates all features of human prostate cancer. The dog is the only large mammal, besides humans, that commonly develops spontaneous prostate cancer. Canine prostate cancer features many similarities with its human counterpart. We sought to develop a canine model of prostate cancer that would more fully represent the features of human prostate cancer than existing models.

METHODS

The Ace-1 canine prostate cancer cell line was injected transabdominally under transrectal ultrasound (TRUS) guidance into the prostates of immunosuppressed, intact, adult male dogs. Tumor progression was monitored by TRUS imaging. Some dogs were subjected to positron emission tomography (PET) for tumor detection. Time of euthanasia was determined based on tumor size, impingement on urethra, and general well-being. Euthanasia was followed by necropsy and histopathology.

RESULTS

Ace-1 tumor cells grew robustly in every dog injected. Tumors grew in subcapsular and parenchymal regions of the prostate. Tumor tissue could be identified using PET. Histological findings were similar to those observed in human prostate cancer. Metastases to lungs and lymph nodes were detected, predominantly in dogs with intraprostatic tumors.

CONCLUSIONS

We have established a minimally invasive dog model of prostate cancer. This model may be valuable for studying prostate cancer progression and distant metastasis.

The multifaceted actions of PTHrP in skeletal metastasis

PTHrP, identified during the elucidation of mediators of malignancy-induced hypercalcemia, plays numerous roles in normal physiology as well as pathological conditions. Recent data support direct functions of PTHrP in metastasis, particularly from tumors with strong bone tropism. Bone provides a unique metastatic environment because of mineralization and the diverse cell populations in the bone marrow. PTHrP is a key regulator of tumor-bone interactions and regulates cells in the bone microenvironment through proliferative and prosurvival activities that prime the 'seed' and the 'soil' of the metastatic lesion. This review highlights recent findings regarding the role of PTHrP in skeletal metastasis, including direct actions in tumor cells, as well as alterations in the bone microenvironment and future perspectives involving the potential roles of PTHrP in the premetastatic niche, and tumor dormancy.

Parathyroid hormone-related protein: an update

PTHrP was identified as a cause of hypercalcemia in cancer patients 25 yr ago. In the intervening years, we have learned that PTHrP and PTH are encoded by related genes that are part of a larger "PTH gene family." This evolutionary relationship permits them to bind to the same type 1 PTH/PTHrP receptor, which explains why humoral hypercalcemia of malignancy resembles hyperparathyroidism. This review will outline basic facts about PTHrP biology and its normal physiological functions, with an emphasis on new findings of the past 5-10 yr. The medical and research communities first became aware of PTHrP because of its involvement in a common paraneoplastic syndrome. Now, research into the basic biology of PTHrP has suggested previously unrecognized connections to a variety of disease states such as osteoporosis, osteoarthritis, and breast cancer and has highlighted how PTHrP itself might be used in therapy for osteoporosis and diabetes. Therefore, the story of this remarkable protein is a paradigm for translational research, having gone from bedside to bench and now back to bedside.