Prenylation inhibition-induced cell death in melanoma: reduced sensitivity in BRAF mutant/PTEN wild-type melanoma cells

HSPB8 counteracts tumor activity of BRAF- and NRAS-mutant melanoma cells by modulation of RAS-prenylation and autophagy

Cutaneous melanoma is one of the most aggressive and lethal forms of skin cancer. Some specific driver mutations have been described in multiple oncogenes including BRAF and NRAS that are mutated in 60-70% and 15-20% of melanoma, respectively. The aim of this study was to evaluate the role of Small Heat Shock Protein B8 (HSPB8) on cell growth and migration of both BLM (BRAF^wt/NRAS^Q61R) and A375 (BRAF^V600E/NRAS^wt) human melanoma cell lines. HSPB8 is a member of the HSPB family of chaperones involved in protein quality control (PQC) system and contributes to chaperone assisted selective autophagy (CASA) as well as in the regulation of mitotic spindle. In cancer, HSPB8 has anti- or pro-tumoral action depending on tumor type. In melanoma cell lines characterized by low HSPB8 levels, we demonstrated that the restoration of HSPB8 expression causes cell growth arrest, reversion of EMT (Epithelial-Mesenchymal Transition)-like phenotype switching and antimigratory effect, independently from the cell mutational status. We demonstrated that HSPB8 regulates the levels of the active prenylated form of NRAS in NRAS-mutant and NRAS-wild-type melanoma cell lines. Consequently, the inhibition of NRAS impairs the activation of Akt/mTOR pathway inducing autophagy activation. Autophagy can play a dual role in regulating cell death and survival. We have therefore demonstrated that HSPB8-induced autophagy is a crucial event that counteracts cell growth in melanoma. Collectively, our results suggest that HSPB8 has an antitumoral action in melanoma cells characterized by BRAF and NRAS mutations.

Nintedanib and Dasatinib Treatments Induce Protective Autophagy as a Potential Resistance Mechanism in MPM Cells

Malignant pleural mesothelioma (MPM) is a rare type of cancer with a grim prognosis. So far, no targetable oncogenic mutation was identified in MPM and biomarkers with predictive value toward drug sensitivity or resistance are also lacking. Nintedanib (BIBF1120) is a small-molecule tyrosine kinase inhibitor that showed promising efficacy preclinically and in phase II trial in MPM as an angiogenesis inhibitor combined with chemotherapy. However, the extended phase III trial failed. In this study, we investigated the effect of nintedanib on one of its targets, the SRC kinase, in two commercial and six novel MPM cell lines. Surprisingly, nintedanib treatment did not inhibit SRC activation in MPM cells and even increased phosphorylation of SRC in several cell lines. Combination treatment with the SRC inhibitor dasatinib could reverse this effect in all cell lines, however, the cellular response was dependent on the drug sensitivity of the cells. In 2 cell lines, with high sensitivity to both nintedanib and dasatinib, the drug combination had no synergistic effect but cell death was initiated. In 2 cell lines insensitive to nintedanib combination treatment reduced cell viability synergisticaly without cell death. In contrast, in these cells both treatments increased the autophagic flux assessed by degradation of the autophagy substrate p62 and increased presence of LC3B-II, increased number of GFP-LC3 puncta and decreased readings of the HiBiT-LC3 reporter. Additionaly, autophagy was synergistically promoted by the combined treatment. At the transcriptional level, analysis of lysosomal biogenesis regulator Transcription Factor EB (TFEB) showed that in all cell lines treated with nintedanib and to a lesser extent, with dasatinib, it became dephosphorylated and accumulated in the nucleus. Interestingly, the expression of certain known TFEB target genes implicated in autophagy or lysosomal biogenesis were significantly modified only in 1 cell line. Finally, we showed that autophagy induction in our MPM cell lines panel by nintedanib and dasatinib is independent of the AKT/mTOR and the ERK pathways. Our study reveals that autophagy can serve as a cytoprotective mechanism following nintedanib or dasatinib treatments in MPM cells.

Bisphosphonates: The role of chemistry in understanding their biological actions and structure-activity relationships, and new directions for their therapeutic use

The bisphosphonates ((HO)2P(O)CR1R2P(O)(OH)2, BPs) were first shown to inhibit bone resorption in the 1960s, but it was not until 30 years later that a detailed molecular understanding of the relationship between their varied chemical structures and biological activity was elucidated. In the 1990s and 2000s, several potent bisphosphonates containing nitrogen in their R2 side chains (N-BPs) were approved for clinical use including alendronate, risedronate, ibandronate, and zoledronate. These are now mostly generic drugs and remain the leading therapies for several major bone-related diseases, including osteoporosis and skeletal-related events associated with bone metastases. The early development of chemistry in this area was largely empirical and only a few common structural features related to strong binding to calcium phosphate were clear. Attempts to further develop structure-activity relationships to explain more dramatic pharmacological differences in vivo at first appeared inconclusive, and evidence for mechanisms underlying cellular effects on osteoclasts and macrophages only emerged after many years of research. The breakthrough came when the intracellular actions on the osteoclast were first shown for the simpler bisphosphonates, via the in vivo formation of P-C-P derivatives of ATP. The synthesis and biological evaluation of a large number of nitrogen-containing bisphosphonates in the 1980s and 1990s led to the key discovery that the antiresorptive effects of these more complex analogs on osteoclasts result mostly from their potency as inhibitors of the enzyme farnesyl diphosphate synthase (FDPS/FPPS). This key branch-point enzyme in the mevalonate pathway of cholesterol biosynthesis is important for the generation of isoprenoid lipids that are utilized for the post-translational modification of small GTP-binding proteins essential for osteoclast function. Since then, it has become even more clear that the overall pharmacological effects of individual bisphosphonates on bone depend upon two key properties: the affinity for bone mineral and inhibitory effects on biochemical targets within bone cells, in particular FDPS. Detailed enzyme-ligand crystal structure analysis began in the early 2000s and advances in our understanding of the structure-activity relationships, based on interactions with this target within the mevalonate pathway and related enzymes in osteoclasts and other cells have continued to be the focus of research efforts to this day. In addition, while many members of the bisphosphonate drug class share common properties, now it is more clear that chemical modifications to create variations in these properties may allow customization of BPs for different uses. Thus, as the appreciation for new potential opportunities with this drug class grows, new chemistry to allow ready access to an ever-widening variety of bisphosphonates continues to be developed. Potential new uses of the calcium phosphate binding mechanism of bisphosphonates for the targeting of other drugs to the skeleton, and effects discovered on other cellular targets, even at non-skeletal sites, continue to intrigue scientists in this research field.

K-Ras prenylation as a potential anticancer target

KRAS is one of the most commonly mutated oncogene and a negative predictive factor for a number of targeted therapies. Therefore, the development of targeting strategies against mutant KRAS is urgently needed. One potential strategy involves disruption of K-Ras membrane localization, which is necessary for its proper function. In this review, we summarize the current data about the importance of membrane-anchorage of K-Ras and provide a critical evaluation of this targeting paradigm focusing mainly on prenylation inhibition. Additionally, we performed a RAS mutation-specific analysis of prenylation-related drug sensitivity data from a publicly available database (https://depmap.org/repurposing/) of three classes of prenylation inhibitors: statins, N-bisphosphonates, and farnesyl-transferase inhibitors. We observed significant differences in sensitivity to N-bisphosphonates and farnesyl-transferase inhibitors depending on KRAS mutational status and tissue of origin. These observations emphasize the importance of factors affecting efficacy of prenylation inhibition, like distinct features of different KRAS mutations, tissue-specific mutational patterns, K-Ras turnover, and changes in regulation of prenylation process. Finally, we enlist the factors that might be responsible for the large discrepancy between the outcomes in preclinical and clinical studies including methodological pitfalls, the incomplete understanding of K-Ras protein turnover, and the variation of KRAS dependency in KRAS mutant tumors.

Allosteric and ATP-Competitive MEK-Inhibition in a Novel Spitzoid Melanoma Model with a RAF- and Phosphorylation-Independent Mutation

Simple Summary

Spitzoid melanoma is a rare tumor type and so far preclinical models for translational research have also been also lacking. We established a cell line from a metastatic spitzoid melanoma that is, according to our knowledge, the first cell model from this tumor type. The cells carried a novel activating mutation in the region of the MEK1 protein that influences the sensitivity of the mutant protein to MEK inhibitors. We tested the cells’ sensitivity to clinically used and newly developed MEK inhibitors in both in vitro and in vivo models. The clinically approved MEK inhibitor strongly reduced both in vitro and in vivo tumor growth and might be an effective therapy for tumors with this kind of MEK mutation.

Abstract

Spitzoid melanoma is a rare malignancy with histological characteristics similar to Spitz nevus. It has a diverse genetic background and in adults, a similarly grim clinical outcome as conventional malignant melanoma. We established a spitzoid melanoma cell line (PF130) from the pleural effusion sample of a 37-year-old male patient. We found that the cell line carries a rare MEK1 mutation (pGlu102_Lys104delinsGln) that belongs to the RAF- and phosphorylation-independent subgroup of MEK1 alternations supposedly insensitive to allosteric MEK inhibitors. The in vivo tumorigenicity was tested in three different models by injecting the cells subcutaneously, intravenously or into the thoracic cavity of SCID mice. In the intrapleural model, macroscopic tumors formed in the chest cavity after two months, while subcutaneously and intravenously delivered cells showed limited growth. In vitro, trametinib—but not selumentinib—and the ATP-competitive MEK inhibitor MAP855 strongly decreased the viability of the cells and induced cell death. In vivo, trametinib but not MAP855 significantly reduced tumor growth in the intrapleural model. To the best of our knowledge, this is the first patient-derived melanoma model with RAF- and phosphorylation-independent MEK mutation and we demonstrated its sensitivity to trametinib.

Zoledronic Acid-Loaded β-TCP Inhibits Tumor Proliferation and Osteoclast Activation: Development of a Functional Bone Substitute for an Efficient Osteosarcoma Treatment

Osteosarcoma has a poor survival rate due to relapse and metastasis. Zoledronic acid (ZOL), an anti-resorptive and anti-tumor agent, is used for treating osteosarcoma. Delivery of ZOL to the target region is difficult due to its high binding affinity to bone minerals. This study developed a novel treatment for osteosarcoma by delivering ZOL to the target region locally and sustainably. In this study, we fabricated a novel bone substitute by loading ZOL on β-tricalcium phosphate (β-TCP). The ZOL-loaded β-TCP (ZOL/β-TCP) would be expected to express the inhibitory effects via both bound-ZOL (bound to β-TCP) and free-ZOL (release from ZOL/β-TCP). To explore the ability to release ZOL from the ZOL/β-TCP, the amount of released ZOL was measured. The released profile indicates that a small amount of ZOL was released, and most of it remained on the β-TCP. Our data showed that ZOL/β-TCP could successfully express the effects of ZOL via both bound-ZOL and free-ZOL. In addition, we examined the biological effects of bound/free-ZOL using osteosarcoma and osteoclasts (target cells). The results showed that two states of ZOL (bound/free) inhibit target cell activities. As a result, ZOL/β-TCP is a promising candidate for application as a novel bone substitute.

Ras inhibition by zoledronic acid effectively sensitizes cervical cancer to chemotherapy

Aberrant activation of Ras is common in several human cancers, including cervical cancer. In this study, we show that Ras function can be inhibited by zoledronic acid (ZA) owing to its ability in inhibiting protein prenylation. Using in-vitro cell culture system and an in-vivo xenograft mouse model, the effects of ZA on cervical cancer cell growth and survival were determined. The molecular mechanisms of ZA's action were analyzed focusing on prenylation and its downstream signaling pathways. ZA inhibited proliferation and induced apoptosis of multiple cervical cancer cell lines regardless of their cellular origin and genetic profiling. The combination of ZA with paclitaxel or doxorubicin was superior to a single drug alone in cervical cancer in vitro and in vivo. Notably, complete inhibition of cervical cancer growth was observed in the combination groups. Mechanistically, ZA inhibited prenylation of oncoproteins. Ras activity was largely affected by ZA in a prenylation-dependent manner. Consistently, Ras-mediated signaling pathways such as Raf/ERK and AKt/mTOR were deactivated in cervical cancer cells exposed to ZA. Overexpression of constitutively active Ras reversed the inhibitory effects of ZA, confirming that Ras inhibition was required for the action of ZA in cervical cancer. Despite extensive efforts, there has been limited progress in the development of direct Ras inhibitors. Our findings suggest that ZA inhibits Ras activity. Our work provides fundamental evidence to repurpose ZA for the treatment of cervical cancer.

HDAC inhibition synergizes with ALK inhibitors to overcome resistance in a novel ALK mutated lung adenocarcinoma model

OBJECTIVES

Somatic chromosomal rearrangements resulting in ALK fusion oncogenes are observed in 3-7 % of lung adenocarcinomas. ALK tyrosine kinase inhibitors (ALKi) induce initially response, however, various resistance mechanisms limit their efficacy. Novel therapeutic approaches are of utmost importance to tailor these targeted therapies.

MATERIALS AND METHODS

A synchronous ALK-rearranged and mutated lung cancer cell line pair was established from malignant pleural effusion (PF240-PE) and carcinosis (PF240-PC) at time of ALKi resistance. Immunohistochemistry, FISH and sequencing were performed in pre- and post-treatment tumors and in both cell lines. Differentiation markers were measured by immunoblot. Viability was tested following treatment with ALKi and/or a pan-HDAC inhibitor. Additionally, a novel treatment-naïve ALK-rearranged cell line served as control. In vivo tumorigenicity was evaluated in subcutaneous xenografts.

RESULTS

Two distinct resistance mutations were identified in different carcinosis tissues at time of resistance, the previously described resistance mutation L1152R and the hitherto uncharacterized E1161K. Strikingly, PF240-PC cells carried E1161K and PF240-PE cells harbored L1152R. Immunohistochemistry and immunoblot identified epithelial-to-mesenchymal transition markers upregulated following ALKi resistance development both in carcinosis tissues and cell lines. While both lines grew as xenografts, they differed in morphology, migration, in vivo growth and sensitivity to ALKi in vitro. Strikingly, the combination of ALKi with SAHA yielded strong synergism.

CONCLUSION

Using a patient-derived ALKi resistant lung cancer model we demonstrated the synergism of HDAC and ALK inhibition. Furthermore, our findings provide strong evidence for intratumoral heterogeneity under targeted therapy and highlight the importance of site-specific mutational analysis.

Next Generation Lipophilic Bisphosphonate Shows Antitumor Effect in Colorectal Cancer In Vitro and In Vivo

Bisphosphonates, despite proven antitumor effect in vitro in many tumor types, are currently used only for treatment of osteoporosis and bone metastasis. Colorectal cancer is the third most commonly diagnosed type of cancer and lacks targeted therapy for RAS or RAF mutation carrying cases. A new lipophilic bisphosphonate showed promising results in lung cancer models, but their effect on colorectal cancer cells was not investigated excessively. Antitumor effects and impact on RAS-related signalization of zoledronic acid (ZA) and a lipophilic bisphosphonate (BPH1222) were investigated on 7 human colorectal cancer cell lines in vitro and in vivo. Furthermore, mutant KRAS dependent effect of prenylation inhibition was investigated using isogeneic cell lines. Both bisphosphonates reduced cell viability in vitro in a dose-dependent manner. Both compounds changed cell cycle distribution similarly by increasing the proportion of cells either in the S or in the subG1 phase or both. However, BPH1222 exerted higher inhibitory effect on spheroid growth than ZA. Interestingly, we found profound alterations in phosphorylation level of Erk and S6 proteins upon ZA or BPH1222 treatment. Furthermore, investigation of a mutant KRAS isogeneic model system suggests that the drugs interfere also with the mutant KRAS proteins. In vivo experiments with KRAS mutant xenograft model also revealed growth inhibitory potential of bisphosphonate treatment. Our results show that lipophilic bisphosphonates might extend the therapeutic spectrum of bisphosphonate drugs and could be considered as additional treatment approaches in colorectal cancer.

The Antitumor Effect of Lipophilic Bisphosphonate BPH1222 in Melanoma Models: The Role of the PI3K/Akt Pathway and the Small G Protein Rheb

Malignant melanoma is one of the most metastatic cancer types, and despite recent success with novel treatment strategies, there is still a group of patients who do not respond to any therapies. Earlier, the prenylation inhibitor hydrophilic bisphosphonate zoledronic acid (ZA) was found to inhibit melanoma growth in vitro, but only a weaker effect was observed in vivo due to its hydrophilic properties. Recently, lipophilic bisphosphonates (such as BPH1222) were developed. Accordingly, for the first time, we compared the effect of BPH1222 to ZA in eight melanoma lines using viability, cell-cycle, clonogenic and spheroid assays, videomicroscopy, immunoblot, and xenograft experiments. Based on 2D and spheroid assays, the majority of cell lines were more sensitive to BPH. The activation of Akt and S6 proteins, but not Erk, was inhibited by BPH. Additionally, BPH had a stronger apoptotic effect than ZA, and the changes of Rheb showed a correlation with apoptosis. In vitro, only M24met cells were more sensitive to ZA than to BPH; however, in vivo growth of M24met was inhibited more strongly by BPH. Here, we present that lipophilic BPH is more effective on melanoma cells than ZA and identify the PI3K pathway, particularly Rheb as an important mediator of growth inhibition.

The role of lipid signaling in the progression of malignant melanoma

In the past decades, a vast amount of data accumulated on the role of lipid signaling pathways in the progression of malignant melanoma, the most metastatic/aggressive human cancer type. Genomic studies identified that PTEN loss is the leading factor behind the activation of the PI3K-signaling pathway in melanoma, mutations of which are one of the main resistance mechanisms behind target therapy failures. On the other hand, illegitimate expressions of megakaryocytic genes p12-lipoxyganse, cyclooxygenase-2, and phosphodiestherase-2/autotaxin (ATX) are mostly involved in the regulation of motility signaling in melanoma through various G-protein-coupled bioactive lipid receptors. Furthermore, endocannabinoid signaling can also be a novel paracrine survival factor in melanoma. Last but not least, prenylation inhibitors acting even on mutated small GTP-ases, such as NRAS of melanoma may offer novel therapeutic opportunities. As regards melanoma, the most effective therapy nowadays is immunotherapy, with the resistance mechanisms also possibly involving the lipid signaling activities of melanoma cells, which further supports the idea of their being therapeutic targets.

An actionable axis linking NFATc2 to EZH2 controls the EMT-like program of melanoma cells

Discovery of new actionable targets and functional networks in melanoma is an urgent need as only a fraction of metastatic patients achieves durable clinical benefit by targeted therapy or immunotherapy approaches. Here we show that NFATc2 expression is associated with an EMT-like transcriptional program and with an invasive melanoma phenotype, as shown by analysis of melanoma cell lines at the mRNA and protein levels, interrogation of the TCGA melanoma dataset and characterization of melanoma lesions by immunohistochemistry. Gene silencing or pharmacological inhibition of NFATc2 downregulated EMT-related genes and AXL, and suppressed c-Myc, FOXM1, and EZH2. Targeting of c-Myc suppressed FOXM1 and EZH2, while targeting of FOXM1 suppressed EZH2. Inhibition of c-Myc, or FOXM1, or EZH2 downregulated EMT-related gene expression, upregulated MITF and suppressed migratory and invasive activity of neoplastic cells. Stable silencing of NFATc2 impaired melanoma cell proliferation in vitro and tumor growth in vivo in SCID mice. In NFATc2⁺ EZH2⁺ melanoma cell lines pharmacological co-targeting of NFATc2 and EZH2 exerted strong anti-proliferative and pro-apoptotic activity, irrespective of BRAF or NRAS mutations and of BRAF inhibitor resistance. These results provide preclinical evidence for a role of NFATc2 in shaping the EMT-like melanoma phenotype and reveal a targetable vulnerability associated with NFATc2 and EZH2 expression in melanoma cells belonging to different mutational subsets.

Pan-RAF and MEK vertical inhibition enhances therapeutic response in non-V600 BRAF mutant cells

BACKGROUND

Currently, there are no available targeted therapy options for non-V600 BRAF mutated tumors. The aim of this study was to investigate the effects of RAF and MEK concurrent inhibition on tumor growth, migration, signaling and apoptosis induction in preclinical models of non-V600 BRAF mutant tumor cell lines.

METHODS

Six BRAF mutated human tumor cell lines CRL5885 (G466 V), WM3629 (D594G), WM3670 (G469E), MDAMB231 (G464 V), CRL5922 (L597 V) and A375 (V600E as control) were investigated. Pan-RAF inhibitor (sorafenib or AZ628) and MEK inhibitor (selumetinib) or their combination were used in in vitro viability, video microscopy, immunoblot, cell cycle and TUNEL assays. The in vivo effects of the drugs were assessed in an orthotopic NSG mouse breast cancer model.

RESULTS

All cell lines showed a significant growth inhibition with synergism in the sorafenib/AZ628 and selumetinib combination. Combination treatment resulted in higher Erk1/2 inhibition and in increased induction of apoptosis when compared to single agent treatments. However, single selumetinib treatment could cause adverse therapeutic effects, like increased cell migration in certain cells, selumetinib and sorafenib combination treatment lowered migratory capacity in all the cell lines. Importantly, combination resulted in significantly increased tumor growth inhibition in orthotropic xenografts of MDAMB231 cells when compared to sorafenib - but not to selumetinib - treatment.

CONCLUSIONS

Our data suggests that combined blocking of RAF and MEK may achieve increased therapeutic response in non-V600 BRAF mutant tumors.

Simvastatin exerts anticancer effects in osteosarcoma cell lines via geranylgeranylation and c-Jun activation

Osteosarcoma is the leading primary bone cancer in young adults and exhibits high chemoresistance rates. Therefore, characterization of both alternative treatment options and the underlying mechanisms is essential. Simvastatin, a cholesterol-lowering drug, has among its pleiotropic effects anticancer potential. Characterizing this potential and the underlying mechanisms in osteosarcoma is the subject of the present study. Human osteosarcoma cells (SaOS-2 and U2OS) were treated with simvastatin (4-66 µM) for 48 or 72 h. The effects of downstream substrate mevalonate (MA) or substrates for isoprenylation farnesyl pyrophosphate (FPP) and geranylgeranyl-pyrophosphate (GGPP) were evaluated using add-back experiments. Tumour growth using MTT assay, apoptosis, cell cycle and signalling cascades involved in simvastatin-induced manipulation were analysed. The results revealed that simvastatin dose-dependently inhibited cell growth. Simvastatin significantly induced apoptosis, increased the Bax/Bcl-2 ratio, and cleavage of caspase-3 and PARP protein. Simvastatin impaired cell cycle progression as shown by significantly increased percentages of cells in the G0/G1 phase and lower percentages of cells in the S phase. Gene expression levels of cell cycle-regulating genes (TP53, CDKN1A and CDK1) were markedly altered. These effects were not completely abolished by FPP, but were reversed by MA and GGPP. JNK and c-Jun phosphorylation was enhanced after simvastatin treatment, while those were abolished when either MA or GGPP were added. In conclusion, simvastatin acts primarily by reducing prenylation to induce apoptosis and reduce osteosarcoma cell growth. Particularly enhanced activation of c-Jun seems to play a pivotal role in osteosarcoma cell death.

Complications of bone metastases from malignant melanoma

INTRODUCTION

Metastatic bone disease (MBD) carries significant morbidity for patients with cancer. MBD from malignant melanoma (MM) is understudied. We examined the characteristics, morbidity, management and outcome of MBD in patients with MM.

METHODS

Patients with metastatic MM managed at two referral cancer centres in England were identified. Those with bone metastases (BMs) were selected. Patient and disease characteristics including skeletal related events (SREs) were extracted from medical records. The Kaplan Meier method was used to calculate median survival.

RESULTS

Five hundred and eighteen patients with metastatic MM were managed between years 2000 and 2008. Eighty nine (17.2%) patients had BMs and are the subject of this study. Median age at diagnosis was 53 years and 55% were males. BMs were identified at the time of diagnosis of metastatic disease in 68.5% patients. Sixty-six (74.2%) had multiple bone lesions and 80.9% had axial skeleton involvement. One hundred and twenty nine skeletal related events occurred in 59 (66.3%) patients (50 radiotherapy, 28 hypercalcaemia, 20 bone fractures, 18 spinal cord compression and 13 orthopaedic surgery). The annual skeletal morbidity rate was 2.5. Median survival from diagnosis of BMs was 17.3 weeks and was 5.6 weeks from the first episode of hypercalcaemia.

CONCLUSION

MBD affects a clinically important proportion (17.2%) of patients with metastatic MM. It carries a substantial morbidity and mortality exceeding that caused by BMs from breast and prostate cancer. These patients should receive the currently licensed bone modifying agents and should be included in clinical trials addressing MBD.

Physiologic Activity of Bisphosphonates – Recent Advances

Background:

Bisphosphonates are drugs commonly used for the medication and prevention of diseases caused by decreased mineral density. Despite such important medicinal use, they display a variety of physiologic activities, which make them promising anti-cancer, anti-protozoal, antibacterial and antiviral agents.

Objective:

To review physiological activity of bisphosphonates with special emphasis on their ongoing and potential applications in medicine and agriculture.

Method:

Critical review of recent literature data.

Results:

Comprehensive review of activities revealed by bisphosphonates.

Conclusion:

although bisphosphonates are mostly recognized by their profound effects on bone physiology their medicinal potential has not been fully evaluated yet. Literature data considering enzyme inhibition suggest possibilities of far more wide application of these compounds. These applications are, however, limited by their low bioavailability and therefore intensive search for new chemical entities overcoming this shortage are carried out.

Low Expression of Mir-137 Predicts Poor Prognosis in Cutaneous Melanoma Patients

BACKGROUND

The present study aimed to measure miR-137 expression in patients with cutaneous melanoma (CM) and to estimate the correlation of miR-137 expression and the prognosis of CM patients.

MATERIAL/METHODS

The expression level of miR-137 was assayed by quantitative real-time PCR (qRT-PCR) and presented as mean ±SD. Chi-square was used to evaluate the relationship between miR-137 expression and clinical characteristics. We used a Kaplan-Meier survival curve to determine the overall survival rate of CM patients. Moreover, the correlation between miR-137 expression and the prognosis of CM patients was confirmed by Cox regression analysis.

RESULTS

The relative expression of miR-137 in CM tissue was 1.59±0.43, while that in paired normal tissue was 2.41±0.54, which was significantly higher. Chi-square analysis showed statistical significance between miR-137 expression and clinical characteristics such as TNM stage, ulcer, and occurrence site (P<0.05). However, no association was found between miR-137 expression and age, sex, or family history (P>0.05). According to the survival curve outcome, patients with low miR-137 expression showed relatively higher mortality (P=0.000) and multivariate analysis verified that low expression of miR-137 predicted poor prognosis of CM patients (HR=8.531, 95% CI=2.950-24.668, P=0.000).

CONCLUSIONS

Compared with paired normal tissues, miR-137 expression was lower in CM tissues. Patients with low miR-137 expression had higher mortality than those with high miR-137 expression, suggesting that low miR-137 expression indicated poor prognosis for CM patients.