Gene Summary

Gene:PTHLH; parathyroid hormone like hormone
Summary:The protein encoded by this gene is a member of the parathyroid hormone family. This hormone, via its receptor, PTHR1, regulates endochondral bone development and epithelial-mesenchymal interactions during the formation of the mammary glands and teeth. It is responsible for most cases of humoral hypercalcemia of malignancy, and mutations in this gene are associated with brachydactyly type E2 (BDE2). Alternatively spliced transcript variants have been found for this gene. There is also evidence for alternative translation initiation from non-AUG (CUG and GUG) start sites, downstream of the initiator AUG codon, resulting in nuclear forms of this hormone. [provided by RefSeq, Nov 2013]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:parathyroid hormone-related protein
Source:NCBIAccessed: 10 March, 2017


What does this gene/protein do?
Show (30)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 10 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Hypercalcemia
  • Biomarkers, Tumor
  • Transcriptional Activation
  • Messenger RNA
  • Chromosome 12
  • Base Sequence
  • Gene Expression
  • Parathyroid Hormone
  • Receptors, Parathyroid Hormone
  • Bone Cancer
  • Neoplasm Proteins
  • Polymerase Chain Reaction
  • Radioimmunoassay
  • Up-Regulation
  • Peptide Hormones
  • Promoter Regions
  • Gene Expression Regulation
  • Gene Expression Profiling
  • Transforming Growth Factor beta
  • Species Specificity
  • Oligonucleotide Array Sequence Analysis
  • Squamous Cell Carcinoma
  • Reagent Kits, Diagnostic
  • Transformation, Genetic
  • Lung Cancer
  • Vitamin D
  • Thyroid Cancer
  • Cell Differentiation
  • Breast Cancer
  • Protein Biosynthesis
  • p53 Protein
  • Immunohistochemistry
  • Parathyroid Hormone-Related Protein
  • Genetic Predisposition
  • Cancer Gene Expression Regulation
  • Cancer RNA
  • Cervical Cancer
  • Molecular Sequence Data
  • Proteins
  • Genome-Wide Association Study
Tag cloud generated 10 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: PTHLH (cancer-related)

Zhu W, Hu X, Xu J, et al.
Effect of PI3K/Akt Signaling Pathway on the Process of Prostate Cancer Metastasis to Bone.
Cell Biochem Biophys. 2015; 72(1):171-7 [PubMed] Related Publications
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.

Kir S, Komaba H, Garcia AP, et al.
PTH/PTHrP Receptor Mediates Cachexia in Models of Kidney Failure and Cancer.
Cell Metab. 2016; 23(2):315-23 [PubMed] Free Access to Full Article Related Publications
Cachexia is a wasting syndrome associated with elevated basal energy expenditure and loss of adipose and muscle tissues. It accompanies many chronic diseases including renal failure and cancer and is an important risk factor for mortality. Our recent work demonstrated that tumor-derived PTHrP drives adipose tissue browning and cachexia. Here, we show that PTH is involved in stimulating a thermogenic gene program in 5/6 nephrectomized mice that suffer from cachexia. Fat-specific knockout of PTHR blocked adipose browning and wasting. Surprisingly, loss of PTHR in fat tissue also preserved muscle mass and improved muscle strength. Similarly, PTHR knockout mice were resistant to cachexia driven by tumors. Our results demonstrate that PTHrP and PTH mediate wasting through a common mechanism involving PTHR, and there exists an unexpected crosstalk mechanism between wasting of fat tissue and skeletal muscle. Targeting the PTH/PTHrP pathway may have therapeutic uses in humans with cachexia.

Kinomura M, Shimada N, Nishikawa M, et al.
Parathyroid Hormone-related Peptide-producing Multiple Myeloma and Renal Impairment.
Intern Med. 2015; 54(23):3029-33 [PubMed] Related Publications
A 68-year-old man was hospitalized and examined for renal impairment. A laboratory analysis showed hypercalcemia. Although the serum parathyroid hormone and serum 1-25(OH)2 vitamin D3 levels were not elevated, the serum parathyroid hormone-related peptide (PTHrP) level was increased. Immunoelectrophoresis of the urine and bone marrow aspiration indicated multiple myeloma (MM). He was diagnosed with the coexistence of cast nephropathy and light chain deposition disease by a renal biopsy. Notably, PTHrP expression was detected in the myeloma cells based on immunohistochemistry and in situ hybridization. It is therefore important to examine the PTHrP concentration in MM patients with hypercalcemia.

Xu C, Wang Z, Cui R, et al.
Co-expression of parathyroid hormone related protein and TGF-beta in breast cancer predicts poor survival outcome.
BMC Cancer. 2015; 15:925 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Better methods to predict prognosis can play a supplementary role in administering individualized treatment for breast cancer patients. Altered expressions of PTHrP and TGF-β have been observed in various types of human cancers. The objective of the current study was to evaluate the association of PTHrP and TGF-β level with the clinicopathological features of the breast cancer patients.
METHODS: Immunohistochemistry was used to examine PTHrP and TGF-β protein expression in 497 cases of early breast cancer, and Kaplan-Meier method and COX's Proportional Hazard Model were applied to the prognostic value of PTHrP and TGF-β expression.
RESULTS: Both over-expressed TGF-β and PTHrP were correlated with the tumor in larger size, higher proportion of axillary lymph node metastasis and later clinical stage. Additionally, the tumors with a high TGF-β level developed poor differentiation, and only TGF-β expression was associated with disease-free survival (DFS) of the breast cancer patients. Followed up for a median of 48 months, it was found that only the patients with negative TGF-β expression had longer DFS (P < 0.05, log-rank test). Nevertheless, those with higher PTHrP expression tended to show a higher rate of bone metastasis (67.6 % vs. 45.8 %, P = 0.019). In ER negative subgroup, those who developed PTHrP positive expression presented poor prognosis (P < 0.05, log-rank test). The patients with both positive TGF-β and PTHrP expression were significantly associated with the high risk of metastases. As indicated by Cox's regression analysis, TGF-β expression and the high proportion of axillary lymph node metastasis served as significant independent predictors for breast cancer recurrence.
CONCLUSIONS: TGF-β and PTHrP were confirmed to be involved in regulating the malignant progression in breast cancer, and PTHrP expression, to be associated with bone metastasis as a potential prognostic marker in ER negative breast cancer.

Zong JC, Wang X, Zhou X, et al.
Gut-derived serotonin induced by depression promotes breast cancer bone metastasis through the RUNX2/PTHrP/RANKL pathway in mice.
Oncol Rep. 2016; 35(2):739-48 [PubMed] Related Publications
Breast cancer metastasizes to the bone in a majority of patients with advanced disease resulting in bone destruction. The underlying mechanisms are complex, and both processes are controlled by an interaction between locally and systemically derived signals. Clinically, breast cancer patients with depression have a higher risk of bone metastasis, yet the etiology and mechanisms are yet to be elucidated. MDA‑MB‑231 breast cancer cells were used to establish a bone metastasis model by using intracardiac injection in nude mice. Chronic mild stress (CMS) was chosen as a model of depression in mice before and after inoculation of the cells. Knockdown of the RUNX‑2 gene was performed by transfection of the cells with shRNA silencing vectors against human RUNX‑2. A co‑culture system was used to test the effect of the MDA‑MB‑231 cells on osteoclasts and osteoblasts. RT‑PCR and western blotting were used to test gene and protein expression, respectively. We confirmed that depression induced bone metastasis by promoting osteoclast activity while inhibiting osteoblast differentiation. Free serotonin led to an increase in the expression of RUNX2 in breast cancer cells (MDA‑MB‑231), which directly inhibited osteoblast differentiation and stimulated osteoclast differentiation by the PTHrP/RANKL pathway, which caused bone destruction and formed osteolytic bone lesions. Additionally, the interaction between depression and breast cancer cells was interrupted by LP533401 or RUNX2 knockdown. In conclusion, depression promotes breast cancer bone metastasis partly through increasing levels of gut‑derived serotonin. Activation of RUNX2 in breast cancer cells by circulating serotonin appears to dissociate coupling between osteoblasts and osteoclasts, suggesting that the suppression of gut‑derived serotonin decreases the rate of breast cancer bone metastasis induced by depression.

Pavlovic M, Arnal-Estapé A, Rojo F, et al.
Enhanced MAF Oncogene Expression and Breast Cancer Bone Metastasis.
J Natl Cancer Inst. 2015; 107(12):djv256 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: There are currently no biomarkers for early breast cancer patient populations at risk of bone metastasis. Identification of mediators of bone metastasis could be of clinical interest.
METHODS: A de novo unbiased screening approach based on selection of highly bone metastatic breast cancer cells in vivo was used to determine copy number aberrations (CNAs) associated with bone metastasis. The CNAs associated with bone metastasis were examined in independent primary breast cancer datasets with annotated clinical follow-up. The MAF gene encoded within the CNA associated with bone metastasis was subjected to gain and loss of function validation in breast cancer cells (MCF7, T47D, ZR-75, and 4T1), its downstream mechanism validated, and tested in clinical samples. A multivariable Cox cause-specific hazard model with competing events (death) was used to test the association between 16q23 or MAF and bone metastasis. All statistical tests were two-sided.
RESULTS: 16q23 gain CNA encoding the transcription factor MAF mediates breast cancer bone metastasis through the control of PTHrP. 16q23 gain (hazard ratio (HR) for bone metastasis = 14.5, 95% confidence interval (CI) = 6.4 to 32.9, P < .001) as well as MAF overexpression (HR for bone metastasis = 2.5, 95% CI = 1.7 to 3.8, P < .001) in primary breast tumors were specifically associated with risk of metastasis to bone but not to other organs.
CONCLUSIONS: These results suggest that MAF is a mediator of breast cancer bone metastasis. 16q23 gain or MAF protein overexpression in tumors may help to select patients at risk of bone relapse.

Bach AS, Derocq D, Laurent-Matha V, et al.
Nuclear cathepsin D enhances TRPS1 transcriptional repressor function to regulate cell cycle progression and transformation in human breast cancer cells.
Oncotarget. 2015; 6(29):28084-103 [PubMed] Free Access to Full Article Related Publications
The lysosomal protease cathepsin D (Cath-D) is overproduced in breast cancer cells (BCC) and supports tumor growth and metastasis formation. Here, we describe the mechanism whereby Cath-D is accumulated in the nucleus of ERα-positive (ER+) BCC. We identified TRPS1 (tricho-rhino-phalangeal-syndrome 1), a repressor of GATA-mediated transcription, and BAT3 (Scythe/BAG6), a nucleo-cytoplasmic shuttling chaperone protein, as new Cath-D-interacting nuclear proteins. Cath-D binds to BAT3 in ER+ BCC and they partially co-localize at the surface of lysosomes and in the nucleus. BAT3 silencing inhibits Cath-D accumulation in the nucleus, indicating that Cath-D nuclear targeting is controlled by BAT3. Fully mature Cath-D also binds to full-length TRPS1 and they co-localize in the nucleus of ER+ BCC where they are associated with chromatin. Using the LexA-VP16 fusion co-activator reporter assay, we then show that Cath-D acts as a transcriptional repressor, independently of its catalytic activity. Moreover, microarray analysis of BCC in which Cath-D and/or TRPS1 expression were silenced indicated that Cath-D enhances TRPS1-mediated repression of several TRPS1-regulated genes implicated in carcinogenesis, including PTHrP, a canonical TRPS1 gene target. In addition, co-silencing of TRPS1 and Cath-D in BCC affects the transcription of cell cycle, proliferation and transformation genes, and impairs cell cycle progression and soft agar colony formation. These findings indicate that Cath-D acts as a nuclear transcriptional cofactor of TRPS1 to regulate ER+ BCC proliferation and transformation in a non-proteolytic manner.

Page JM, Merkel AR, Ruppender NS, et al.
Matrix rigidity regulates the transition of tumor cells to a bone-destructive phenotype through integrin β3 and TGF-β receptor type II.
Biomaterials. 2015; 64:33-44 [PubMed] Free Access to Full Article Related Publications
Cancer patients frequently develop skeletal metastases that significantly impact quality of life. Since bone metastases remain incurable, a clearer understanding of molecular mechanisms regulating skeletal metastases is required to develop new therapeutics that block establishment of tumors in bone. While many studies have suggested that the microenvironment contributes to bone metastases, the factors mediating tumors to progress from a quiescent to a bone-destructive state remain unclear. In this study, we hypothesized that the "soil" of the bone microenvironment, specifically the rigid mineralized extracellular matrix, stimulates the transition of the tumor cells to a bone-destructive phenotype. To test this hypothesis, we synthesized 2D polyurethane (PUR) films with elastic moduli ranging from the basement membrane (70 MPa) to cortical bone (3800 MPa) and measured expression of genes associated with mechanotransduction and bone metastases. We found that expression of Integrin β3 (Iβ3), as well as tumor-produced factors associated with bone destruction (Gli2 and parathyroid hormone related protein (PTHrP)), significantly increased with matrix rigidity, and that blocking Iβ3 reduced Gli2 and PTHrP expression. To identify the mechanism by which Iβ3 regulates Gli2 and PTHrP (both are also known to be regulated by TGF-β), we performed Förster resonance energy transfer (FRET) and immunoprecipitation, which indicated that Iβ3 co-localized with TGF-β Receptor Type II (TGF-β RII) on rigid but not compliant films. Finally, transplantation of tumor cells expressing Iβ3 shRNA into the tibiae of athymic nude mice significantly reduced PTHrP and Gli2 expression, as well as bone destruction, suggesting a crucial role for tumor-produced Iβ3 in disease progression. This study demonstrates that the rigid mineralized bone matrix can alter gene expression and bone destruction in an Iβ3/TGF-β-dependent manner, and suggests that Iβ3 inhibitors are a potential therapeutic approach for blocking tumor transition to a bone destructive phenotype.

Hou R, Wang YW, Liang HF, et al.
Animal and cellular models of hepatocellular carcinoma bone metastasis: establishment and characterisation.
J Cancer Res Clin Oncol. 2015; 141(11):1931-43 [PubMed] Related Publications
BACKGROUND: An increasingly high occurrence of bone metastases in hepatocellular carcinoma (HCC) patients highlights the importance of fundamental research on HCC bone metastasis, which has been limited in its success due to the lack of a model system.
PURPOSE: Establishment of animal and cellular models of HCC bone metastasis and discovery of HCC bone metastasis-related genes.
METHODS: Luciferase-transfected HCC cell lines HCCLM3, MHCC97H, and SMMC-7721 were used to inoculate nude mice intracardially. Formation of bone metastases was examined by bioluminescence imaging, SPECT, and pathology study. Metastatic cells in bone were isolated and subcultured. Differences between bone metastatic cells and their parental cells were studied by in vitro/in vivo assays.
RESULTS: Mouse model of HCC bone metastasis was successfully established. Injected tumour cells formed metastases in the skull, the spine, the hind limbs, and the sternum, causing osteolytic lesions via act of MMP-1 and recruitment of osteoclasts. Four bone metastatic cell lines were extracted from HCCLM3-inoculated mice and were demonstrated to exhibit a much stronger ability to form bone metastases as well as other phenotypes, including enhanced in vitro migration/invasion and colony formation. Moreover, the expression of PTHrP, MMP-1, and CTGF was significantly elevated in bone metastatic cells compared to parental HCC cells.
CONCLUSION: The nude mouse model and bone metastatic cell lines together provide an effective simulation of HCC bone metastasis. This model system will become powerful tool with which to explore the mechanisms and therapies of HCC bone metastasis. Additionally, PTHrP, MMP-1, and CTGF are candidate genes related to HCC bone metastasis.

Xu J, Acharya S, Sahin O, et al.
14-3-3ζ turns TGF-β's function from tumor suppressor to metastasis promoter in breast cancer by contextual changes of Smad partners from p53 to Gli2.
Cancer Cell. 2015; 27(2):177-92 [PubMed] Free Access to Full Article Related Publications
Transforming growth factor β (TGF-β) functions as a tumor suppressor in premalignant cells but as a metastasis promoter in cancer cells. The dichotomous functions of TGF-β are proposed to be dictated by different partners of its downstream effector Smads. However, the mechanism for the contextual changes of Smad partners remained undefined. Here, we demonstrate that 14-3-3ζ destabilizes p53, a Smad partner in premalignant mammary epithelial cells, by downregulating 14-3-3σ, thus turning off TGF-β's tumor suppression function. Conversely, 14-3-3ζ stabilizes Gli2 in breast cancer cells, and Gli2 partners with Smads to activate PTHrP and promote TGF-β-induced bone metastasis. The 14-3-3ζ-driven contextual changes of Smad partners from p53 to Gli2 may serve as biomarkers and therapeutic targets of TGF-β-mediated cancer progression.

Taipaleenmäki H, Browne G, Akech J, et al.
Targeting of Runx2 by miR-135 and miR-203 Impairs Progression of Breast Cancer and Metastatic Bone Disease.
Cancer Res. 2015; 75(7):1433-44 [PubMed] Free Access to Full Article Related Publications
Progression of breast cancer to metastatic bone disease is linked to deregulated expression of the transcription factor Runx2. Therefore, our goal was to evaluate the potential for clinical use of Runx2-targeting miRNAs to reduce tumor growth and bone metastatic burden. Expression analysis of a panel of miRNAs regulating Runx2 revealed a reciprocal relationship between the abundance of Runx2 protein and two miRNAs, miR-135 and miR-203. These miRNAs are highly expressed in normal breast epithelial cells where Runx2 is not detected, and absent in metastatic breast cancer cells and tissue biopsies that express Runx2. Reconstituting metastatic MDA-MB-231-luc cells with miR-135 and miR-203 reduced the abundance of Runx2 and expression of the metastasis-promoting Runx2 target genes IL11, MMP-13, and PTHrP. In addition, tumor cell viability was decreased and migration suppressed in vitro. Orthotopic implantation of MDA-MB-231-luc cells delivered with miR-135 or miR-203, followed by an intratumoral administration of the synthetic miRNAs, reduced the tumor growth and spontaneous metastasis to bone. Furthermore, intratibial injection of these miRNA-delivered cells impaired tumor growth in the bone environment and inhibited bone resorption. Importantly, reconstitution of Runx2 in MDA-MB-231-luc cells delivered with miR-135 and miR-203 reversed the inhibitory effect of the miRNAs on tumor growth and metastasis. Thus, we have identified that aberrant expression of Runx2 in aggressive tumor cells is related to the loss of specific Runx2-targeting miRNAs and that a clinically relevant replacement strategy by delivery of synthetic miRNAs is a candidate for a therapeutic approach to prevent metastatic bone disease by this route.

Johnstone CN, Smith YE, Cao Y, et al.
Functional and molecular characterisation of EO771.LMB tumours, a new C57BL/6-mouse-derived model of spontaneously metastatic mammary cancer.
Dis Model Mech. 2015; 8(3):237-51 [PubMed] Free Access to Full Article Related Publications
The translation of basic research into improved therapies for breast cancer patients requires relevant preclinical models that incorporate spontaneous metastasis. We have completed a functional and molecular characterisation of a new isogenic C57BL/6 mouse model of breast cancer metastasis, comparing and contrasting it with the established BALB/c 4T1 model. Metastatic EO771.LMB tumours were derived from poorly metastatic parental EO771 mammary tumours. Functional differences were evaluated using both in vitro assays and spontaneous metastasis assays in mice. Results were compared to non-metastatic 67NR and metastatic 4T1.2 tumours of the 4T1 model. Protein and transcript levels of markers of human breast cancer molecular subtypes were measured in the four tumour lines, as well as p53 (Tp53) tumour-suppressor gene status and responses to tamoxifen in vivo and in vitro. Array-based expression profiling of whole tumours identified genes and pathways that were deregulated in metastatic tumours. EO771.LMB cells metastasised spontaneously to lung in C57BL/6 mice and displayed increased invasive capacity compared with parental EO771. By immunohistochemical assessment, EO771 and EO771.LMB were basal-like, as was the 4T1.2 tumour, whereas 67NR had a luminal phenotype. Primary tumours from all lines were negative for progesterone receptor, Erb-b2/Neu and cytokeratin 5/6, but positive for epidermal growth factor receptor (EGFR). Only 67NR displayed nuclear estrogen receptor alpha (ERα) positivity. EO771 and EO771.LMB expressed mutant p53, whereas 67NR and 4T1.2 were p53-null. Integrated molecular analysis of both the EO771/EO771.LMB and 67NR/4T1.2 pairs indicated that upregulation of matrix metalloproteinase-3 (MMP-3), parathyroid hormone-like hormone (Pthlh) and S100 calcium binding protein A8 (S100a8) and downregulation of the thrombospondin receptor (Cd36) might be causally involved in metastatic dissemination of breast cancer.

Lv Z, Wu X, Cao W, et al.
Parathyroid hormone-related protein serves as a prognostic indicator in oral squamous cell carcinoma.
J Exp Clin Cancer Res. 2014; 33:100 [PubMed] Free Access to Full Article Related Publications
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.

Susa T, Ikaga R, Kajitani T, et al.
Wild-type and specific mutant androgen receptor mediates transcription via 17β-estradiol in sex hormone-sensitive cancer cells.
J Cell Physiol. 2015; 230(7):1594-606 [PubMed] Related Publications
We previously encountered regulatory processes wherein dihydrotestosterone (DHT) exerted its inhibitory effect on parathyroid hormone-related protein (PTHrP) gene repression through the estrogen receptor (ER)α, but not the androgen receptor (AR), in breast cancer MCF-7 cells. Here, we investigated whether such aberrant ligand-nuclear receptor (NR) interaction is present in prostate cancer LNCaP cells. First, we confirmed that LNCaP cells expressed large amounts of AR at negligible levels of ERα/β or progesterone receptor. Both suppression of PTHrP and activation of prostate-specific antigen genes were observed after independent administration of 17β-estradiol (E2), DHT, or R5020. Consistent with the notion that the LNCaP AR lost its ligand specificity due to a mutation (Thr-Ala877), experiments with siRNA targeting the respective NR revealed that the AR monopolized the role of the mediator of shared hormone-dependent regulation, which was invariably associated with nuclear translocation of this mutant AR. Microarray analysis of gene regulation by DHT, E2, or R5020 disclosed that more than half of the genes downstream of the AR (Thr-Ala877) overlapped in the LNCaP cells. Of particular interest, we realized that the AR (wild-type [wt]) and AR (Thr-Ala877) were equally responsible for the E2-AR interactions. Fluorescence microscopy experiments demonstrated that both EGFP-AR (wt) and EGFP-AR (Thr-Ala877) were exclusively localized within the nucleus after E2 or DHT treatment. Furthermore, reporter assays revealed that some other cancer cells exhibited aberrant E2-AR (wt) signaling similar to that in the LNCaP cells. We herein postulate the presence of entangled interactions between wt AR and E2 in certain hormone-sensitive cancer cells.

Matsuo T, Dat le T, Komatsu M, et al.
Early growth response 4 is involved in cell proliferation of small cell lung cancer through transcriptional activation of its downstream genes.
PLoS One. 2014; 9(11):e113606 [PubMed] Free Access to Full Article Related Publications
Small cell lung cancer (SCLC) is aggressive, with rapid growth and frequent bone metastasis; however, its detailed molecular mechanism remains poorly understood. Here, we report the critical role of early growth factor 4 (EGR4), a DNA-binding, zinc-finger transcription factor, in cell proliferation of SCLC. EGR4 overexpression in HEK293T cells conferred significant upregulation of specific splice variants of the parathyroid hormone-related protein (PTHrP) gene, resulting in enhancement of the secretion of PTHrP protein, a known mediator of osteolytic bone metastasis. More importantly, depletion of EGR4 expression by siRNA significantly suppressed growth of the SCLC cell lines, SBC-5, SBC-3 and NCI-H1048. On the other hand, introduction of EGR4 into NIH3T3 cells significantly enhanced cell growth. We identified four EGR4 target genes, SAMD5, RAB15, SYNPO and DLX5, which were the most significantly downregulated genes upon depletion of EGR4 expression in all of the SCLC cells examined, and demonstrated the direct recruitment of EGR4 to their promoters by ChIP and luciferase reporter analysis. Notably, knockdown of the expression of these genes by siRNA remarkably suppressed the growth of all the SCLC cells. Taken together, our findings suggest that EGR4 likely regulates the bone metastasis and proliferation of SCLC cells via transcriptional regulation of several target genes, and may therefore be a promising target for the development of anticancer drugs for SCLC patients.

Heikinheimo K, Kurppa KJ, Laiho A, et al.
Early dental epithelial transcription factors distinguish ameloblastoma from keratocystic odontogenic tumor.
J Dent Res. 2015; 94(1):101-11 [PubMed] Related Publications
The aim of the study was to characterize the molecular relationship between ameloblastoma and keratocystic odontogenic tumor (KCOT) by means of a genome-wide expression analysis. Total RNA from 27 fresh tumor samples of 15 solid/multicystic intraosseous ameloblastomas and 12 sporadic KCOTs was hybridized on Affymetrix whole genome arrays. Hierarchical clustering separated ameloblastomas and KCOTs into 2 distinct groups. The gene set enrichment analysis based on 303 dental genes showed a similar separation of ameloblastomas and KCOTs. Early dental epithelial markers PITX2, MSX2, DLX2, RUNX1, and ISL1 were differentially overexpressed in ameloblastoma, indicating its dental identity. Also, PTHLH, a hormone involved in tooth eruption and invasive growth, was one of the most differentially upregulated genes in ameloblastoma. The most differentially overexpressed genes in KCOT were squamous epithelial differentiation markers SPRR1A, KRTDAP, and KRT4, as well as DSG1, a component of desmosomal cell-cell junctions. Additonally, the epithelial stem cell marker SOX2 was significantly upregulated in KCOT when compared with ameloblastoma. Taken together, the gene expression profile of ameloblastoma reflects differentiation from dental lamina toward the cap/bell stage of tooth development, as indicated by dental epithelium-specific transcription factors. In contrast, gene expression of KCOT indicates differentiation toward keratinocytes.

Xiang W, Jiang T, Guo F, et al.
Evaluating the role of PTH in promotion of chondrosarcoma cell proliferation and invasion by inhibiting primary cilia expression.
Int J Mol Sci. 2014; 15(11):19816-31 [PubMed] Free Access to Full Article Related Publications
Chondrosarcoma is characterized by secretion of a cartilage-like matrix, with high proliferation ability and metastatic potential. Previous studies have shown that parathyroid hormone-related protein (PTHrP) has a close relationship with various tumor types. The objectives of this study were to research the function played by PTHrP in human chondrosarcoma, especially targeting cell proliferation and invasion, and to search for the potential interaction between PTHrP and primary cilia in tumorigenesis. Surgical resection tissues and the human chondrosarcoma cell line SW1353 were used in the scientific research. Cells were stimulated with an optimum concentration of recombinant PTH (1-84), and siRNA was used to interfere with internal PTHrP. Cell proliferation and invasion assays were applied, including MTS-8 cell proliferation assay, Western blot, RT-PCR, Transwell invasion assay, and immunohistochemistry and immunofluorescence assays. A high level of PTHrP expression was found in human chondrosarcoma tissues, and recombinant PTH exhibited positive promotion in tumor cell proliferation and invasion. In the meantime, PTHrP could inhibit the assembly of primary cilia and regulate downstream gene expression. These findings indicate that PTHrP can regulate tumor cell proliferation and invasion ability, possibly through suppression of primary cilia assembly. Thus, restricting PTHrP over-expression is a feasible potential therapeutic method for chondrosarcoma.

Johnson RW, Merkel AR, Page JM, et al.
Wnt signaling induces gene expression of factors associated with bone destruction in lung and breast cancer.
Clin Exp Metastasis. 2014; 31(8):945-59 [PubMed] Free Access to Full Article Related Publications
Parathyroid hormone-related protein (PTHrP) is an important regulator of bone destruction in bone metastatic tumors. Transforming growth factor-beta (TGF-β) stimulates PTHrP production in part through the transcription factor Gli2, which is regulated independent of the Hedgehog signaling pathway in osteolytic cancer cells. However, inhibition of TGF-β in vivo does not fully inhibit tumor growth in bone or tumor-induced bone destruction, suggesting other pathways are involved. While Wnt signaling regulates Gli2 in development, the role of Wnt signaling in bone metastasis is unknown. Therefore, we investigated whether Wnt signaling regulates Gli2 expression in tumor cells that induce bone destruction. We report here that Wnt activation by β-catenin/T cell factor 4 (TCF4) over-expression or lithium chloride (LiCl) treatment increased Gli2 and PTHrP expression in osteolytic cancer cells. This was mediated through the TCF and Smad binding sites within the Gli2 promoter as determined by promoter mutation studies, suggesting cross-talk between TGF-β and Wnt signaling. Culture of tumor cells on substrates with bone-like rigidity increased Gli2 and PTHrP production, enhanced autocrine Wnt activity and led to an increase in the TCF/Wnt signaling reporter (TOPFlash), enriched β-catenin nuclear accumulation, and elevated Wnt-related genes by PCR-array. Stromal cells serve as an additional paracrine source of Wnt ligands and enhanced Gli2 and PTHrP mRNA levels in MDA-MB-231 and RWGT2 cells in vitro and promoted tumor-induced bone destruction in vivo in a β-catenin/Wnt3a-dependent mechanism. These data indicate that a combination of matrix rigidity and stromal-secreted factors stimulate Gli2 and PTHrP through Wnt signaling in osteolytic breast cancer cells, and there is significant cross-talk between the Wnt and TGF-β signaling pathways. This suggests that the Wnt signaling pathway may be a potential therapeutic target for inhibiting tumor cell response to the bone microenvironment and at the very least should be considered in clinical regimens targeting TGF-β signaling.

Liu L, Chen X, Wang Y, et al.
Notch3 is important for TGF-β-induced epithelial-mesenchymal transition in non-small cell lung cancer bone metastasis by regulating ZEB-1.
Cancer Gene Ther. 2014; 21(9):364-72 [PubMed] Related Publications
The Notch signaling pathway plays an important role in the bone metastasis microenvironment. Although recent evidence suggests that Notch signaling contributes to bone metastasis in breast and prostate cancer, its role and possible mechanisms in non-small cell lung cancer (NSCLC) bone metastasis are not yet clear. Here, we show that Notch3 is overexpressed in NSCLC bone metastases. The inhibition of Notch3 by small interfering RNA transfection decreased the invasion ability of NSCLC cells and transforming growth factor (TGF)-induced interleukin (IL)-6 and parathyroid hormone-related protein (pTHrP) expression in vitro. We also observed that Notch3 induced a strong morphological transformation, promoting the epithelial-mesenchymal transition (EMT). Western blotting and real-time polymerase chain reaction assays revealed that the forced overexpression of Notch3 induced the expression and activity of ZEB-1 and subsequent suppression of E-cadherin and upregulation of fibronectin, contributing to EMT and invasion. Western blotting and immunofluorescence assays showed that RNA interference-mediated ZEB-1 suppression blocked Notch-induced EMT-like transformation and subsequently reversed the observed effects on E-cadherin and downregulated fibronectin. A luciferase reporter system showed that Notch-induced ZEB-1 requires a functional binding site in the ZEB-1 promoter. In vitro invasion assays showed that the inhibition of ZEB-1 can decrease Notch3-promoted invasion and the expression of pTHrP and IL-6. Our results demonstrated that Notch upregulates ZEB-1, which contributes to TGF-β-induced EMT-like transformation and bone metastasis in NSCLC.

Huang DC, Yang XF, Ochietti B, et al.
Parathyroid hormone-related protein: potential therapeutic target for melanoma invasion and metastasis.
Endocrinology. 2014; 155(10):3739-49 [PubMed] Related Publications
The role of PTHrP in the highly metastatic human melanoma disease is not known. This study investigates the mechanisms of action of this secreted factor through homozygous inactivation of the Pthrp gene in A375 human melanoma cells. In vitro, Pthrp-ablated cells (knockout [KO]-A375, -/-) showed decreased motility and anchorage-independent growth, rounder morphology, and a significant reduction in invasion capacity compared with nonablated A375 cells (wild-type [WT]-A375, +/+). PTHrP peptide 1-34 and conditioned medium from WT-A375 cells partially restored the invasive phenotype in KO-A375. Pthrp ablation substantially decreased actin polymerization, matrix metallopeptidase 9 expression and focal adhesion kinase phosphorylation. In vivo, green fluorescent protein-transduced ablated and nonablated A375 cells were injected intracardially or sc into nude mice to study proliferation and multiorgan metastasis. Dissemination of injected Pthrp-ablated cells to lung and liver was reduced by 85% and 50%, respectively, compared with nonablated controls (120 hours after injection). The number of metastatic lesions and the percentage of animals with metastasis were markedly lower in mice injected with Pthrp-ablated A375, and 45% of these animals survived a 7-week period compared with 15% of mice injected with nonablated WT-A375. When mice injected with WT-A375 were treated with our blocking anti-PTHrP monoclonal antibody raised against the first 33 amino acids of human PTHrP, tumor size was decreased by more than 80% over 4 weeks and survival was significantly improved over 8 months. This study provides direct evidence of the major role for PTHrP in melanoma invasion and metastasis and suggests that agents that suppress PTHrP may be beneficial against melanoma progression.

Ho PW, Goradia A, Russell MR, et al.
Knockdown of PTHR1 in osteosarcoma cells decreases invasion and growth and increases tumor differentiation in vivo.
Oncogene. 2015; 34(22):2922-33 [PubMed] Related Publications
Osteosarcoma (OS) is the most common cancer of bone. Parathyroid hormone (PTH) regulates calcium homeostasis and bone development, while the paracrine/autocrine PTH-related protein (PTHrP) has central roles in endochondral bone formation and bone remodeling. Using a murine OS model, we found that OS cells express PTHrP and the common PTH/PTHrP receptor (PTHR1). To investigate the role of PTHR1 signaling in OS cell behavior, we used shRNA to reduce PTHR1 expression. This only mildly inhibited proliferation in vitro, but markedly reduced invasion through collagen and reduced expression of RANK ligand (RANKL). Administration of PTH(1-34) did not stimulate OS proliferation in vivo but, strikingly, PTHR1 knockdown resulted in a profound growth inhibition and increased differentiation/mineralization of the tumors. Treatment with neutralizing antibody to PTHrP did not recapitulate the knockdown of PTHR1. Consistent with this lack of activity, PTHrP was predominantly intracellular in OS cells. Knockdown of PTHR1 resulted in increased expression of late osteoblast differentiation genes and upregulation of Wnt antagonists. RANKL production was reduced in knockdown tumors, providing for reduced homotypic signaling through the receptor, RANK. Loss of PTHR1 resulted in the coordinated loss of gene signatures associated with the polycomb repressive complex 2 (PRC2). Using Ezh2 inhibitors, we demonstrate that the increased expression of osteoblast maturation markers is in part mediated by the loss of PRC2 activity. Collectively these results demonstrate that PTHR1 signaling is important in maintaining OS proliferation and undifferentiated state. This is in part mediated by intracellular PTHrP and through regulation of the OS epigenome.

Kir S, White JP, Kleiner S, et al.
Tumour-derived PTH-related protein triggers adipose tissue browning and cancer cachexia.
Nature. 2014; 513(7516):100-4 [PubMed] Free Access to Full Article Related Publications
Cachexia is a wasting disorder of adipose and skeletal muscle tissues that leads to profound weight loss and frailty. About half of all cancer patients suffer from cachexia, which impairs quality of life, limits cancer therapy and decreases survival. One key characteristic of cachexia is higher resting energy expenditure levels than in healthy individuals, which has been linked to greater thermogenesis by brown fat. How tumours induce brown fat activity is unknown. Here, using a Lewis lung carcinoma model of cancer cachexia, we show that tumour-derived parathyroid-hormone-related protein (PTHrP) has an important role in wasting, through driving the expression of genes involved in thermogenesis in adipose tissues. Neutralization of PTHrP in tumour-bearing mice blocked adipose tissue browning and the loss of muscle mass and strength. Our results demonstrate that PTHrP mediates energy wasting in fat tissues and contributes to the broader aspects of cancer cachexia. Thus, neutralization of PTHrP might hold promise for ameliorating cancer cachexia and improving patient survival.

Bundela S, Sharma A, Bisen PS
Potential therapeutic targets for oral cancer: ADM, TP53, EGFR, LYN, CTLA4, SKIL, CTGF, CD70.
PLoS One. 2014; 9(7):e102610 [PubMed] Free Access to Full Article Related Publications
In India, oral cancer has consistently ranked among top three causes of cancer-related deaths, and it has emerged as a top cause for the cancer-related deaths among men. Lack of effective therapeutic options is one of the main challenges in clinical management of oral cancer patients. We interrogated large pool of samples from oral cancer gene expression studies to identify potential therapeutic targets that are involved in multiple cancer hallmark events. Therapeutic strategies directed towards such targets can be expected to effectively control cancer cells. Datasets from different gene expression studies were integrated by removing batch-effects and was used for downstream analyses, including differential expression analysis. Dependency network analysis was done to identify genes that undergo marked topological changes in oral cancer samples when compared with control samples. Causal reasoning analysis was carried out to identify significant hypotheses, which can explain gene expression profiles observed in oral cancer samples. Text-mining based approach was used to detect cancer hallmarks associated with genes significantly expressed in oral cancer. In all, 2365 genes were detected to be differentially expressed genes, which includes some of the highly differentially expressed genes like matrix metalloproteinases (MMP-1/3/10/13), chemokine (C-X-C motif) ligands (IL8, CXCL-10/-11), PTHLH, SERPINE1, NELL2, S100A7A, MAL, CRNN, TGM3, CLCA4, keratins (KRT-3/4/13/76/78), SERPINB11 and serine peptidase inhibitors (SPINK-5/7). XIST, TCEAL2, NRAS and FGFR2 are some of the important genes detected by dependency and causal network analysis. Literature mining analysis annotated 1014 genes, out of which 841 genes were statistically significantly annotated. The integration of output of various analyses, resulted in the list of potential therapeutic targets for oral cancer, which included targets such as ADM, TP53, EGFR, LYN, CTLA4, SKIL, CTGF and CD70.

Zhou W, Yin H, Wang T, et al.
MiR-126-5p regulates osteolysis formation and stromal cell proliferation in giant cell tumor through inhibition of PTHrP.
Bone. 2014; 66:267-76 [PubMed] Related Publications
Parathyroid hormone-related protein (PTHrP) has been identified to play a crucial role in osteolysis formation and stromal cell (GCTSC) proliferation in giant cell tumor (GCT). MiR-126-5p is an intronic miRNA identified as tumor suppressor in many tumors, but its role in GCT is poorly understood. We found that miR-126-5p was decreased in GCT and could directly regulate PTHrP expression. Furthermore, miR-126-5p could control osteoclast (OC) differentiation, GCTSC proliferation and osteolysis formation in GCT through negative regulation of PTHrP. Thus, these results suggest that miR-126-5p could directly target PTHrP and have a tumor suppressor function in GCT.

Tanaka M, Yamazaki Y, Kanno Y, et al.
Ewing's sarcoma precursors are highly enriched in embryonic osteochondrogenic progenitors.
J Clin Invest. 2014; 124(7):3061-74 [PubMed] Free Access to Full Article Related Publications
Ewing's sarcoma is a highly malignant bone tumor found in children and adolescents, and the origin of this malignancy is not well understood. Here, we introduced a Ewing's sarcoma-associated genetic fusion of the genes encoding the RNA-binding protein EWS and the transcription factor ETS (EWS-ETS) into a fraction of cells enriched for osteochondrogenic progenitors derived from the embryonic superficial zone (eSZ) of long bones collected from late gestational murine embryos. EWS-ETS fusions efficiently induced Ewing's sarcoma-like small round cell sarcoma formation by these cells. Analysis of the eSZ revealed a fraction of a precursor cells that express growth/differentiation factor 5 (Gdf5), the transcription factor Erg, and parathyroid hormone-like hormone (Pthlh), and selection of the Pthlh-positive fraction alone further enhanced EWS-ETS-dependent tumor induction. Genes downstream of the EWS-ETS fusion protein were quite transcriptionally active in eSZ cells, especially in regions in which the chromatin structure of the ETS-responsive locus was open. Inhibition of β-catenin, poly (ADP-ribose) polymerase 1 (PARP1), or enhancer of zeste homolog 2 (EZH2) suppressed cell growth in a murine model of Ewing's sarcoma, suggesting the utility of the current system as a preclinical model. These results indicate that eSZ cells are highly enriched in precursors to Ewing's sarcoma and provide clues to the histogenesis of Ewing's sarcoma in bone.

Yao M, Murakami T, Shioi K, et al.
Tumor signatures of PTHLH overexpression, high serum calcium, and poor prognosis were observed exclusively in clear cell but not non clear cell renal carcinomas.
Cancer Med. 2014; 3(4):845-54 [PubMed] Free Access to Full Article Related Publications
High serum calcium (Ca) due to aberrant secretion of tumor parathyroid hormone-like hormone (PTHLH) is a well-known paraneoplastic sign and is associated with poor prognosis in patients with renal cell carcinoma (RCC). However, the status of serum Ca and tumor PTHLH expression have not been verified using the 2004 World Health Organization (WHO) renal tumor classification. We retrospectively reviewed corrected serum Ca levels at initial onset (n = 683) and/or as of recurrence (n = 71) in patients with RCC. We also examined a total of 623 renal parenchymal tumor samples for PTHLH mRNA expressions by quantitative real-time PCR. High serum Ca concomitant with PTHLH overexpression in tumors was observed exclusively in clear cell RCC but not in other non clear cell subtype tumors, including papillary, chromophobe, collecting-duct, unclassified, and other rare subtype RCCs or in benign oncocytomas and angiomyolipomas. In clear cell RCC, PTHLH expression was significantly high in male patients, and was associated with a symptomatic presentation, higher grade, and higher stage cases, whereas it was not associated with VHL gene status. Univariate analyses demonstrated that high PTHLH expression was strongly associated with poor outcome both in overall survival (OS) and disease-free survival (DFS) for patients who underwent standard nephrectomy. Further multivariate Cox analyses revealed that the PTHLH expressions remained as independent prognostic parameters for OS but not for DFS. These data suggest that the previously characterized tumor signatures of high serum Ca due to high PTHLH expression and poor prognosis are clear cell RCC-specific features, whereas these characteristics are rare in non clear cell RCCs.

Yan Z, Jin S, Wei Z, et al.
Discoidin domain receptor 2 facilitates prostate cancer bone metastasis via regulating parathyroid hormone-related protein.
Biochim Biophys Acta. 2014; 1842(9):1350-63 [PubMed] Related Publications
Prostate cancer frequently metastasizes to the skeleton but the underlying mechanism remains largely undefined. Discoidin domain receptor 2 (DDR2) is a member of receptor tyrosine kinase (RTK) family and is activated by collagen binding. This study aimed to investigate the function and detailed mechanism of DDR2 in prostate cancer bone dissemination. Herein we found that DDR2 was strongly expressed in bone-metastatic prostate cancer cells and tissues compared to that in normal controls. Enhanced expression of constitutively activated DDR2 led to elevation in motility and invasiveness of prostate cancer cells, whereas knockdown of DDR2 through specific shRNA caused a dramatic repression. Knockdown of DDR2 in prostate cancer cells resulted in significant decrease in the proliferation, differentiation and function of osteoblast. Over-expression of DDR2 in prostate cancer cells resulted in notable acceleration of osteoclast differentiation and bone resorption, whereas knockdown of DDR2 exhibited the opposite effects. An intrabone injection bone metastasis animal model demonstrated that DDR2 promoted osteolytic metastasis in vivo. Molecular evidence demonstrated that DDR2 regulated the expression, secretion, and promoter activity of parathyroid hormone-related protein (PTHrP), via modulating Runx2 phosphorylation and transactivity. DDR2 was responsive to TGF-β and involved in TGF-β-mediated osteoclast activation and bone resorption. In addition, DDR2 facilitated prostate cancer cells adhere to type I collagen. This study reveals for the first time that DDR2 plays an essential role in prostate cancer bone metastasis. The mechanism disclosure may provide therapeutic targets for the treatment of prostate cancer.

Wang Y, Lei R, Zhuang X, et al.
DLC1-dependent parathyroid hormone-like hormone inhibition suppresses breast cancer bone metastasis.
J Clin Invest. 2014; 124(4):1646-59 [PubMed] Free Access to Full Article Related Publications
Bone metastasis is a frequent complication of breast cancer that is often accelerated by TGF-β signaling; however, little is known about how the TGF-β pathway is regulated during bone metastasis. Here we report that deleted in liver cancer 1 (DLC1) is an important regulator of TGF-β responses and osteolytic metastasis of breast cancer cells. In murine models, breast cancer cells lacking DLC1 expression exhibited enhanced capabilities of bone metastasis. Knockdown of DLC1 in cancer cells promoted bone metastasis, leading to manifested osteolysis and accelerated death in mice, while DLC1 overexpression suppressed bone metastasis. Activation of Rho-ROCK signaling in the absence of DLC1 mediated SMAD3 linker region phosphorylation and TGF-β-induced expression of parathyroid hormone-like hormone (PTHLH), leading to osteoclast maturation for osteolytic colonization. Furthermore, pharmacological inhibition of Rho-ROCK effectively reduced PTHLH production and breast cancer bone metastasis in vitro and in vivo. Evaluation of clinical breast tumor samples revealed that reduced DLC1 expression was linked to elevated PTHLH expression and organ-specific metastasis to bone. Overall, our findings define a stroma-dependent paradigm of Rho signaling in cancer and implicate Rho-TGF-β crosstalk in osteolytic bone metastasis.

Satcher RL, Pan T, Cheng CJ, et al.
Cadherin-11 in renal cell carcinoma bone metastasis.
PLoS One. 2014; 9(2):e89880 [PubMed] Free Access to Full Article Related Publications
Bone is one of the common sites of metastases from renal cell carcinoma (RCC), however the mechanism by which RCC preferentially metastasize to bone is poorly understood. Homing/retention of RCC cells to bone and subsequent proliferation are necessary steps for RCC cells to colonize bone. To explore possible mechanisms by which these processes occur, we used an in vivo metastasis model in which 786-O RCC cells were injected into SCID mice intracardially, and organotropic cell lines from bone, liver, and lymph node were selected. The expression of molecules affecting cell adhesion, angiogenesis, and osteolysis were then examined in these selected cells. Cadherin-11, a mesenchymal cadherin mainly expressed in osteoblasts, was significantly increased on the cell surface in bone metastasis-derived 786-O cells (Bo-786-O) compared to parental, liver, or lymph node-derived cells. In contrast, the homing receptor CXCR4 was equivalently expressed in cells derived from all organs. No significant difference was observed in the expression of angiogenic factors, including HIF-1α, VEGF, angiopoeitin-1, Tie2, c-MET, and osteolytic factors, including PTHrP, IL-6 and RANKL. While the parental and Bo-786-O cells have similar proliferation rates, Bo-786-O cells showed an increase in migration compared to the parental 786-O cells. Knockdown of Cadherin-11 using shRNA reduced the rate of migration in Bo-786-O cells, suggesting that Cadherin-11 contributes to the increased migration observed in bone-derived cells. Immunohistochemical analysis of cadherin-11 expression in a human renal carcinoma tissue array showed that the number of human specimens with positive cadherin-11 activity was significantly higher in tumors that metastasized to bone than that in primary tumors. Together, these results suggest that Cadherin-11 may play a role in RCC bone metastasis.

Ongkeko WM, Burton D, Kiang A, et al.
Parathyroid hormone related-protein promotes epithelial-to-mesenchymal transition in prostate cancer.
PLoS One. 2014; 9(1):e85803 [PubMed] Free Access to Full Article Related Publications
Parathyroid hormone-related protein (PTHrP) possesses a variety of physiological and developmental functions and is also known to facilitate the progression of many common cancers, notably their skeletal invasion, primarily by increasing bone resorption. The purpose of this study was to determine whether PTHrP could promote epithelial-to-mesenchymal transition (EMT), a process implicated in cancer stem cells that is critically involved in cancer invasion and metastasis. EMT was observed in DU 145 prostate cancer cells stably overexpressing either the 1-141 or 1-173 isoform of PTHrP, where there was upregulation of Snail and vimentin and downregulation of E-cadherin relative to parental DU 145. By contrast, the opposite effect was observed in PC-3 prostate cancer cells where high levels of PTHrP were knocked-down via lentiviral siRNA transduction. Increased tumor progression was observed in PTHrP-overexpressing DU 145 cells while decreased progression was observed in PTHrP-knockdown PC-3 cells. PTHrP-overexpressing DU 145 formed larger tumors when implanted orthoptopically into nude mice and in one case resulted in spinal metastasis, an effect not observed among mice injected with parental DU 145 cells. PTHrP-overexpressing DU 145 cells also caused significant bone destruction when injected into the tibiae of nude mice, while parental DU 145 cells caused little to no destruction of bone. Together, these results suggest that PTHrP may work through EMT to promote an aggressive and metastatic phenotype in prostate cancer, a pathway of importance in cancer stem cells. Thus, continued efforts to elucidate the pathways involved in PTHrP-induced EMT as well as to develop ways to specifically target PTHrP signaling may lead to more effective therapies for prostate cancer.

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