Apoptosis and metastasis: increased apoptosis resistance of metastatic cancer cells is associated with the profound deficiency of apoptosis execution mechanisms

Novel Venetin-1 nanoparticle from earthworm coelomic fluid as a promising agent for the treatment of non-small cell lung cancer

The present research shows the antitumor activity of a protein-polysaccharide complex Venetin-1 obtained from the coelomic fluid of Dendrobaena veneta earthworms against A549 cancer cells. The investigations are a continuation of experiments on the antitumor activity of coelomic fluid obtained from this species. The Venetin-1 nanoparticle was obtained after thermal treatment of the coelomic fluid, separation from coelomocytes, filtration, and lyophilization. The preparation showed a selective effect on cancer cells, whereas normal cells were unaffected. Venetin-1 was effective against the lung cancer cells at doses of 31.3 and 62.5 µg/ml, and the results were imaged using light microscopy and scanning electron microscopy (SEM). The cells died mainly via the apoptosis pathway. Necrotic cells appeared sporadically in the microscopic view. SEM imaging revealed complete destruction of the A549 cells after the incubation with Venetin-1. The atomic force microscopy (AFM) analyses showed changes in the topography, peak force error images, and Young's modulus (elasticity) of the A549 cells after the incubation with Venetin-1. The transmission electron cryomicroscopy (Cryo-TEM) analysis indicated a polymeric nature of the analyzed preparation. The samples of Venetin-1 showed a very homogeneous size profile with the microparticle size of approximately 58.23 nm. A significant decrease in Venetin-1 binding to sphingomyelin was observed. Venetin-1 lost its pore-forming activity or deactivation of the pore-forming activity occurred. This confirms the absence of hemolytic capacity of Venetin-1 towards red blood cells. The conducted analyses show the suitability of the obtained complex for biomedical research. The next step will consist in analyses of the effect of Venetin-1 on the immune system in mice.

Canine and feline uveal melanocytic tumours: Histologic and immunohistochemical characteristics of 32 cases

Objective

Gross, histopathological, and immunohistochemical characteristics of uveal melanocytic neoplasms in dogs and cats were investigated.

Samples

Thirty‐two enucleated globes with uveal melanocytic neoplasms, 27 from dogs and 5 from cats, were examined.

Procedures

Morphological characteristics of uveal melanocytic neoplasms in dogs and cats were evaluated with anti‐PNL2, anti‐Melan‐A, anti‐Ki‐67, anti‐caspase‐3, and anti‐BAP1 immunomarkers. Statistical analysis was performed to compare canine melanocytomas and melanomas.

Results

The 32 uveal neoplasms were classified as melanocytomas (19/27 in dogs) or melanomas (8/27 in dogs, 5/5 in cats). Most tumours (84%) were located in the anterior uvea. Neoplastic cells were classified as epithelioid, spindle‐shaped, mixed, or special type (balloon and signet ring cells). The percentage of cells with melanin, melanin concentration within cells, anisocytosis and anisokaryosis, mitotic count, lymphocytic inflammation, necrosis, vascular invasion, and glaucoma were also characterized. Anisocytosis, percentage of neoplastic cells with melanin, mitotic count, and indices (proliferation and apoptotic) varied significantly between canine uveal melanomas and melanocytomas; in general, melanomas had greater cell variability, were less pigmented, and had a higher mitotic count. The melanocytic origin of the neoplasms was confirmed by positive anti‐PNL2 immunolabelling (29/32) and positive anti‐Melan‐A immunolabelling (3/32). In canine uveal melanomas, anisocytosis and anisokaryosis correlated with less pigmentation and minimal pigmentation correlated with a high percentage of immunolabelling for caspase‐3.

Conclusions

Uveal melanocytomas were more common in dogs, and uveal melanomas were more frequent in cats. Anisocytosis, percentage of neoplastic cells with melanin, and mitotic count are important histologic characteristics of malignancy to evaluate in uveal melanocytic neoplasms. The proliferation and apoptotic indices are relevant when comparing malignant tumours with benign tumours.

The Role of Necroptosis in ROS-Mediated Cancer Therapies and Its Promising Applications

Over the past decades, promising therapies targeting different signaling pathways have emerged. Among these pathways, apoptosis has been well investigated and targeted to design diverse chemotherapies. However, some patients are chemoresistant to these therapies due to compromised apoptotic cell death. Hence, exploring alternative treatments aimed at different mechanisms of cell death seems to be a potential strategy for bypassing impaired apoptotic cell death. Emerging evidence has shown that necroptosis, a caspase-independent form of cell death with features between apoptosis and necrosis, can overcome the predicament of drug resistance. Furthermore, previous studies have also indicated that there is a close correlation between necroptosis and reactive oxygen species (ROS); both necroptosis and ROS play significant roles both under human physiological conditions such as the regulation of inflammation and in cancer biology. Several small molecules used in experiments and clinical practice eliminate cancer cells via the modulation of ROS and necroptosis. The molecular mechanisms of these promising therapies are discussed in detail in this review.

Knock-down of the TIM/TIPIN complex promotes apoptosis in melanoma cells

The Timeless (TIM) and it's interacting partner TIPIN protein complex is well known for its role in replication checkpoints and normal DNA replication processes. Recent studies revealed the involvement of TIM and TIPIN in human malignancies; however, no evidence is available regarding the expression of the TIM/TIPIN protein complex or its potential role in melanoma. Therefore, we investigated the role of this complex in melanoma.

To assess the role of the TIM/TIPIN complex in melanoma, we analyzed TIM/TIPIN expression data from the publicly accessible TCGA online database, Western blot analysis, and RT-qPCR in a panel of melanoma cell lines. Lentivirus-mediated TIM/TIPIN knockdown in A375 melanoma cells was used to examine proliferation, colony formation, and apoptosis. A xenograft tumor formation assay was also performed.

The TIM/TIPIN complex is frequently overexpressed in melanoma cells compared to normal melanocytes. We also discovered that the overexpression of TIM and TIPIN was significantly associated with poorer prognosis of melanoma patients. Furthermore, we observed that shRNA-mediated knockdown of TIM and TIPIN reduced cell viability and proliferation due to the induction of apoptosis and increased levels of γH2AX, a marker of DNA damage. In a xenograft tumor nude mouse model, shRNA-knockdown of TIM/TIPIN significantly reduced tumor growth.

Our results suggest that the TIM/TIPIN complex plays an important role in tumorigenesis of melanoma, which might reveal novel approaches for the development of new melanoma therapies. Our studies also provide a beginning structural basis for understanding the assembly of the TIM/TIPIN complex. Further mechanistic investigations are needed to determine the complex’s potential as a biomarker of melanoma susceptibility. Targeting TIM/TIPIN might be a potential therapeutic strategy against melanoma.

Apoptosis as a Prognostic Factor in Colorectal Carcinoma: Comparison of TUNEL Method and Immunohistochemical Expression of Caspase-3

The development of colorectal cancer is known to be characterized by a sequence of events during which normal colonic epithelium gradually transforms to carcinoma, the adenoma-carcinoma sequence. Apoptosis plays an important role in the development and maintenance of tissue homeostasis. Currently, there is no agreement in the literature about the prognosis of apoptosis in colorectal cancer. The number of studies examining the expression of caspases in colorectal cancer is very limited, and they have not examined any correlation between expression and patient survival. This study included histologic samples from 179 patients diagnosed with colon cancer. We used the TdT-mediated X-dUTP nick end labeling method and caspase-3 labeling to identify the degree of apoptosis. Our results show that lower apoptotic index measured by TdT-mediated X-dUTP nick end labeling method and lower immnuhistochemical expression of caspase-3 is associated with shorter disease-free survival and overall survival. However, only apoptotic index is proven to be an independent survival indicator. The results of our study are consistent with the proposed models of carcinogenesis of colorectal cancer that emphasize resistance to apoptosis as a decisive factor in the progression of the disease and resistance to treatment.

The expression and prognostic significance of Drp1 in lung cancer: A bioinformatics analysis and immunohistochemistry

BACKGROUND

Dynamin-related protein 1 (Drp1) plays important roles in tumorigenesis, including lung cancer. However, the effect of Drp1 in lung cancer remains unclear. The present study was aimed to investigate the clinical significance and effect of Drp1 on prognosis of lung cancer.

METHODS

Oncomine and The Cancer Genome Atlas (TCGA) databases were selected to predict the differential expression levels of Drp1 in lung cancer. Then, 70 cases of lung cancer and normal tissues were collected and immunohistochemistry was used to detect the expression of Drp1. In addition, Kaplan-Meier Plotter database and TCGA database were used to verify the correlation between Drp1 expression and the clinical prognosis in lung cancer patients.

RESULTS

Drp1 was significantly overexpressed in lung cancer tissues based on Oncomine and TCGA databases (P < .05). Moreover, results from immunohistochemistry showed that Drp1 protein level in lung cancer was also significantly higher than that in the matched normal tissues (P < .05). Prognostic analysis from Kaplan-Meier Plotter database with the chosen probe IDs of 203105_s_at suggested that Drp1 was negatively correlated to overall survival (OS) of lung cancer patients (HR = 1.16, 95% CI: 1.02-1.31; P = .025), but not in the probe IDs of 226154_at (HR = 0.86, 95% CI: 0.73-1.01; P = .069). However, prognosis from TCGA database showed inconsistent results in which high expression of Drp1 was correlated with worse survival probability of all, male, female in lung adenocarcinoma (P < .05), but not in LUSC (P > .05).

CONCLUSION

Drp1 was highly expressed in lung cancer based on bioinformatics analysis and tissue microarray, but there was a lot of inconsistency in prognosis depending on different levels of Drp1 from the bioinformatics analysis.

Nanoparticle-Mediated Therapeutic Agent Delivery for Treating Metastatic Breast Cancer-Challenges and Opportunities

Breast cancer (BC) is the second leading cause of cancer-related death in American women and more than 90% of BC-related death is caused by metastatic BC (MBC). This review stresses the limited success of traditional therapies as well as the use of nanomedicine for treating MBC. Understanding the biological barriers of MBC that nanoparticle in vivo trafficking must overcome could provide valuable new insights for translating nanomedicine from the bench side to the bedside. A view about nanomedicine applied in BC therapy has been summarized with their present status, which is gaining attention in the clinically-applied landscape. The progressions of drug/gene delivery systems, especially the status of their preclinical or clinical trials, are also discussed. Here we highlight that the treatment of metastasis, in addition to the extensively described inhibition of primary tumor growth, is an indispensable requirement for nanomedicine. Along with more innovations in material chemistry and more progressions in biology, nanomedicine will constantly supply more exciting new approaches for targeted drug/gene delivery against MBC.

Novel evidence for a PIWI-interacting RNA (piRNA) as an oncogenic mediator of disease progression, and a potential prognostic biomarker in colorectal cancer

Background

Emerging evidence suggests that PIWI-interacting RNAs (piRNAs) may be important epigenetic regulators of gene expression in human cancers; however, their functional and clinical significance in colorectal cancer (CRC) remains unknown.

Methods

We performed piRNA expression profiling in paired cancer and normal tissues through small RNA-sequencing. The clinical significance of candidate piRNAs was investigated, and independently validated in 771 CRC patients from three independent cohorts. The biological function of piRNAs was characterized in cell lines, followed by identification and validation of downstream target genes in CRC tissues.

Results

We identified piR-1245 as a novel and frequently overexpressed noncoding RNA in CRC, and its expression significantly correlated with advanced and metastatic disease. Patients with high piR-1245 expression experienced significantly shorter overall survival, and multivariate analysis identified its expression to serve as an independent prognostic biomarker in CRC. Functionally, piR-1245 acts as an oncogene and promotes tumor progression, and gene expression profiling results identified a panel of downstream target-genes involved in regulating cell survival pathway. Based upon piRNA:mRNA sequence complementarity, we identified a panel of tumor suppressor genes (ATF3, BTG1, DUSP1, FAS,NFKBIA, UPP1, SESN2, TP53INP1 and MDX1) as direct targets of piR-1245, and successfully validated an inverse correlation between their expression and piR-1245 in CRC.

Conclusions

We for the first time have identified the role for a PIWI-interacting noncoding RNA, piR-1245, as a novel oncogene and a potential prognostic biomarker in colorectal cancer.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0767-3) contains supplementary material, which is available to authorized users.

Activation of endogenous human stem cell-associated retroviruses (SCARs) and therapy-resistant phenotypes of malignant tumors

Recent reports revealed consistent activation of specific endogenous retroviral elements in human preimplantation embryos and embryonic stem cells. Activity of stem cell associated retroviruses (SCARs) has been implicated in seeding thousands of human-specific regulatory sequences in the hESC genome. Activation of specific SCARs has been demonstrated in patients diagnosed with multiple types of cancer, autoimmune diseases, and neurodegenerative disorders, and appears associated with clinically lethal therapy resistant death-from-cancer phenotypes in a sub-set of cancer patients diagnosed with different types of malignant tumors. A hallmark feature of human-specific SCAR integration sites is deletions of ancestral DNA. Analysis of human-specific genetic loci of SCARs' stemness networks in tumor samples of TCGA cohorts representing 29 cancer types suggests that this approach may facilitate identification of pan-cancer genomic signatures of clinically-lethal disease defined by the presence of somatic non-silent mutations, gene-level copy number changes, and transcripts and proteins' expression of SCAR-regulated host genes. Present analyses indicate that multiple lines of strong circumstantial evidence support the hypothesis that activation of SCARs' networks may play an important role in cancer progression and metastasis, perhaps contributing to the emergence of clinically-lethal therapy-resistant death-from-cancer phenotypes.

miR-520h is crucial for DAPK2 regulation and breast cancer progression

MicroRNAs (miRNAs) are small RNAs that suppress gene expression by their interaction with 3'untranslated region of specific target mRNAs. Although the dysregulation of miRNAs has been identified in human cancer, only a few of these miRNAs have been functionally documented in breast cancer. Thus, defining the important miRNA and functional target involved in chemoresistance is an urgent need for human breast cancer treatment. In this study, we, for the first time, identified a key role of miRNA 520h (miR-520h) in drug resistance. Through protecting cells from paclitaxel-induced apoptosis, expression of miR-520h promoted the drug resistance of human breast cancer cells. Bioinformatics prediction, compensatory mutation and functional validation further confirmed the essential role of miR-520h-suppressed Death-associated protein kinase 2 (DAPK2) expression, as restoring DAPK2 abolished miR-520h-promoted drug resistance, and knockdown of DAPK2 mitigated cell death caused by the depletion of miR-520h. Furthermore, we observed that higher level of miR-520h is associated with poor prognosis and lymph node metastasis in human breast cancer patients. These results show that miR-520h is not only an independent prognostic factor, but is also a potential functional target for future applications in cancer therapeutics.

Spatial heterogeneity in drug concentrations can facilitate the emergence of resistance to cancer therapy

Acquired resistance is one of the major barriers to successful cancer therapy. The development of resistance is commonly attributed to genetic heterogeneity. However, heterogeneity of drug penetration of the tumor microenvironment both on the microscopic level within solid tumors as well as on the macroscopic level across metastases may also contribute to acquired drug resistance. Here we use mathematical models to investigate the effect of drug heterogeneity on the probability of escape from treatment and the time to resistance. Specifically we address scenarios with sufficiently potent therapies that suppress growth of all preexisting genetic variants in the compartment with the highest possible drug concentration. To study the joint effect of drug heterogeneity, growth rate, and evolution of resistance, we analyze a multi-type stochastic branching process describing growth of cancer cells in multiple compartments with different drug concentrations and limited migration between compartments. We show that resistance is likely to arise first in the sanctuary compartment with poor drug penetrations and from there populate non-sanctuary compartments with high drug concentrations. Moreover, we show that only below a threshold rate of cell migration does spatial heterogeneity accelerate resistance evolution, otherwise deterring drug resistance with excessively high migration rates. Our results provide new insights into understanding why cancers tend to quickly become resistant, and that cell migration and the presence of sanctuary sites with little drug exposure are essential to this end.

Failure of cancer therapy is commonly attributed to the outgrowth of pre-existing resistant mutants already present prior to treatment, yet there is increasing evidence that the tumor microenvironment influences cell sensitivity to drugs and thus mediates the evolution of resistance during treatment. Here, we take into consideration important aspects of the tumor microenvironment, including spatial drug gradients and differential rates of cell proliferation. We show that the dependence of fitness on space together with cell migration facilitates the emergence of acquired resistance. Our analysis indicates that resistant cells that are selected for in compartments with high concentrations are likely to disseminate from sanctuary sites where they first acquire resistance preceding migration. The results suggest that it would be helpful to improve clinical outcomes by combining targeted therapy with anti-metastatic treatment aimed at constraining cell motility as well as by enhancing drug transportation and distribution throughout all metastatic compartments.

Beyond cell death - antiapoptotic Bcl-2 proteins regulate migration and invasion of colorectal cancer cells in vitro

Migration and invasion of malignant cells are prerequisites for cancer progression and metastasis. The Bcl-2 family of proteins consists of about 25 members and has been extensively studied in the context of apoptosis. Despite the fact that small molecules targeting Bcl-2 proteins have already entered clinical trials, very few studies investigated a role of antiapoptotic Bcl-2 proteins beside cell death in the context of metastasis. The aim of this study was to dissect a potential role of the antiapoptotic Bcl-2 proteins Mcl-1, Bcl-2 and Bcl-x_L on migration and invasion of colorectal cancer cells independent of their cell death control function. We used migration and invasion assays as well as three dimensional cell cultures to analyze colorectal cancer cell lines (HT29 and SW480) after siRNA mediated knockdown or overexpression of Mcl-1, Bcl-2 or Bcl-x_L. We observed neither spontaneous cell death induction nor impaired proliferation of cells lacking Mcl-1, Bcl-2 or Bcl-x_L. In contrast, knockdown of Mcl-1 led to increased proliferation. Strikingly, we demonstrate a profound impairment of both, migration and invasion, of colorectal cancer cells after Mcl-1, Bcl-2 or Bcl-x_L knockdown. This phenotype was completely revised in cells overexpressing Mcl-1, Bcl-2 or Bcl-x_L. The most pronounced effect among the investigated proteins was observed for Bcl-2. The data presented indicate a pivotal role of Mcl-1, Bcl-2 and Bcl-x_L for migration and invasion of colorectal cancer cells independent of their known antiapoptotic effects. Thus, our study illustrates novel antitumoral mechanisms of Bcl-2 protein targeting.

Chicken skin mucosa surrounding adult colorectal adenomas is a risk factor for carcinogenesis. Am J Clin Oncol. 2012;35:527-532. [PMID: 21654311 DOI: 10.1097/coc.0b013e31821dedf7]

OBJECTIVES

Transformation of normal mucosa to colorectal adenoma could occur over a span of 5 to 20 years, whereas transformation of colorectal adenoma to colorectal cancer could take an additional 5 to 15 years. This study aims to investigate whether chicken skin mucosa (CSM) surrounding adult colorectal adenomas may be a risk factor for carcinogenesis.

METHODS

Patients with colorectal mucosa, colorectal adenomas without CSM, or colorectal adenomas with CSM were enrolled in this study. Immunohistochemistry and enzyme-linked immunosorbent assays were used to determine the expression levels of proliferation markers (ki-67 and COX-2) and apoptosis factors (survivin and caspase-3) in tissues.

RESULTS

The expression of ki-67 was significantly higher in colorectal adenomas with CSM compared with colorectal adenoma tissues (P < 0.01). Colorectal adenocarcinoma showed significantly higher levels of COX-2 protein compared with normal colorectal mucosa and colorectal adenoma tissues (P < 0.001). COX-2 expression was significantly higher in adenomas with CSM compared with normal colorectal mucosa (P < 0.001). Adenomas with CSM and adenocarcinomas exhibited significantly higher levels of survivin when compared with colorectal adenoma without CSM and normal tissues (P < 0.001). Although we found no significant difference in caspase-3 levels between adenocarcinomas and adenomas with CSM, caspase-3 expression was significantly lower in these tissues when compared with colorectal adenomas without CSM and normal mucosa (P < 0.001).

CONCLUSIONS

The biological characteristics of colorectal adenomas with CSM were different from those of colorectal adenomas without CSM. Colorectal adenomas with CSM exhibited active cell proliferation and inhibition of apoptotic pathways, suggesting an increased risk of carcinogenesis in these adenomas.

Defects in mitochondrial fission protein dynamin-related protein 1 are linked to apoptotic resistance and autophagy in a lung cancer model

Evasion of apoptosis is implicated in almost all aspects of cancer progression, as well as treatment resistance. In this study, resistance to apoptosis was identified in tumorigenic lung epithelial (A549) cells as a consequence of defects in mitochondrial and autophagic function. Mitochondrial function is determined in part by mitochondrial morphology, a process regulated by mitochondrial dynamics whereby the joining of two mitochondria, fusion, inhibits apoptosis while fission, the division of a mitochondrion, initiates apoptosis. Mitochondrial morphology of A549 cells displayed an elongated phenotype–mimicking cells deficient in mitochondrial fission protein, Dynamin-related protein 1 (Drp1). A549 cells had impaired Drp1 mitochondrial recruitment and decreased Drp1-dependent fission. Cytochrome c release and caspase-3 and PARP cleavage were impaired both basally and with apoptotic stimuli in A549 cells. Increased mitochondrial mass was observed in A549 cells, suggesting defects in mitophagy (mitochondrial selective autophagy). A549 cells had decreased LC3-II lipidation and lysosomal inhibition suggesting defects in autophagy occur upstream of lysosomal degradation. Immunostaining indicated mitochondrial localized LC3 punctae in A549 cells increased after mitochondrial uncoupling or with a combination of mitochondrial depolarization and ectopic Drp1 expression. Increased inhibition of apoptosis in A549 cells is correlated with impeded mitochondrial fission and mitophagy. We suggest mitochondrial fission defects contribute to apoptotic resistance in A549 cells.

Apoptosis resistance and PKC signaling: distinguishing features of high and low metastatic cells

The complexity of the process of metastasis is widely recognized. We report herein on a recurrent feature of high compared to low metastatic cells that is linked to their ability to survive early after their arrival at secondary sites. Using novel fluorescent-based imaging strategies that assess tumor cell interaction with the lung microenvironment, we have determined that most high and low metastatic cells can be distinguished within 6 hours of their arrival in the lung and further that this difference is defined by the ability of high metastatic cells to resist apoptosis at the secondary site. Despite the complexity of the metastatic cascade, the performance of cells during this critical window is highly defining of their metastatic proclivity. To explore mechanisms, we next evaluated biochemical pathways that may be linked to this survival phenotype in highly metastatic cells. Interestingly, we found no association between the Akt survival pathway and this metastatic phenotype. Of all pathways examined, only protein kinase C (PKC) activation was significantly linked to survival of highly metastatic cells. These data provide a conceptual understanding of a defining difference between high and low metastatic cells. The connection to PKC activation may provide a biologic rationale for the use of PKC inhibition in the prevention of metastatic progression.

Melanoma: from mutations to medicine

Melanoma is often considered one of the most aggressive and treatment-resistant human cancers. It is a disease that, due to the presence of melanin pigment, was accurately diagnosed earlier than most other malignancies and that has been subjected to countless therapeutic strategies. Aside from early surgical resection, no therapeutic modality has been found to afford a high likelihood of curative outcome. However, discoveries reported in recent years have revealed a near avalanche of breakthroughs in the melanoma field-breakthroughs that span fundamental understanding of the molecular basis of the disease all the way to new therapeutic strategies that produce unquestionable clinical benefit. These discoveries have been born from the successful fruits of numerous researchers working in many-sometimes-related, although also distinct-biomedical disciplines. Discoveries of frequent mutations involving BRAF(V600E), developmental and oncogenic roles for the microphthalmia-associated transcription factor (MITF) pathway, clinical efficacy of BRAF-targeted small molecules, and emerging mechanisms underlying resistance to targeted therapeutics represent just a sample of the findings that have created a striking inflection in the quest for clinically meaningful progress in the melanoma field.

Site-specific cytomorphology of disseminated PC-3 prostate cancer cells visualized in vivo with fluorescent proteins

Circulating tumor cells (CTC) may reach multiple organ sites. However, CTC seeding and growth in distant organs is not random. Each metastatic site may contain a specific subpopulation of the original metastatic tumor capable of growing at that site. The fluorescent orthotopic prostate cancer model (PC-3-GFP) model was used for immunomagnetic capture of CTC. The captured CTC were efficiently cultivated in vitro. PC-3-GFP cells were also isolated from various metastatic sites, grown in vitro and examined under fluorescence microscopy. The differential morphology was compared of primary tumor cells, CTC and disseminated (DTC) from multiple metastatic sites, from nude mice with orthotopic PC-3-GFP. The cultured captured CTC and DTC from various organs have distinctive morphologies. Distinct cancer cell morphologies were observed at different metastatic sites as well as among CTC. The distinct morphologies were maintained during in vitro culture. The results demonstrate extensive tumor heterogeneity that could account for the widely different behavior of cancer cells in a single tumor. Further hetereogeneity testing would be a big promise for personalizing the cancer treatment in the future.

The p53-independent induction of apoptosis in breast cancer cells in response to proteasome inhibitor bortezomib

An important hallmark of cancer cells is acquired resistance toward apoptosis. The apoptotic pathway is the most well-defined cell death program and is characterized by several morphological and biochemical features. The tumor suppressor protein p53 is a critical regulator of apoptosis in many cell types. p53 stimulates a wide network of signals that act through either extrinsic or intrinsic pathways of apoptosis. However, a number of studies have shown that apoptosis can be induced in a p53-independent manner as well. In this study, we examined the mechanism of apoptosis in p53-null breast cancer cells in response to the proteasome inhibitor bortezomib. Initially, we determined the p53 status of 4T1 breast carcinoma and 4THMpc (a highly mestatic derivative of 4T1) cells and verified that both cells are p53 deficient. It was subsequently shown that apoptosis can be induced in both cells in a dose-dependent manner in response to bortezomib treatment, based on DNA fragmentation evidence. Western blot analyses of ubiquitin-protein conjugates additionally showed that the proteasome is potently inhibited by bortezomib in p53-null 4T1 and 4THMpc cells. The results presented in the current study also show that caspase-3 is significantly activated in response to the treatment with bortezomib, implying that induction of apoptosis in these p53-deficient cells is occurring via caspase-3. The additional results presented here suggest that the pro-apoptotic proteins Bad, Noxa, and Puma are not critical regulators of apoptosis induction in p53-null 4T1 and 4THMpc cells. Similarly, there was no difference in the expression level of Mcl-1 in treated cells, suggesting that this anti-apoptotic protein is also uninvolved in the apoptotic response resulting from bortezomib treatment. In contrast, a very significant upregulation of the anti-apoptotic protein Hsp25/27 was detected in these p53-deficient cells after treatment with bortezomib. If the increased expression of Hsp25/27 protein levels are muting the apoptotic effects of the bortezomib treatment, then the apoptosis-inducing effects of such proteasome inhibitors might be increased with approaches simultaneously inhibiting Hsp25/27 protein in p53-deficient cells.

Differences in chemosensitivity between primary and paired metastatic lung cancer tissues: In vitro analysis based on the collagen gel droplet embedded culture drug test (CD-DST)

BACKGROUND

To elucidate the differences in chemosensitivity to anticancer drugs between primary and metastatic lesions in non-small cell lung cancer (NSCLC) patients, we examined the in vitro chemosensitivities of surgically resected NSCLC tissues.

METHODS

A total of 32 specimens were enrolled: 26 specimens of primary lesions paired with metastases in the lymph node, 3 specimens of primary lesions paired with metastases in the adrenal gland, and 3 specimens of primary lesions paired with metastases in the lung. The collagen gel droplet embedded culture drug test (CD-DST) was applied to examine the sensitivity of the tissues to anticancer drugs, including cisplatin, gemcitabine, vinorelbine, docetaxel and 5-fluorouracil.

RESULTS

The degree of in vitro sensitivity to each anticancer drug varied between the primary and metastatic lesions. The sensitivity of the paired metastatic lesions was significantly lower than that of the primary lesions only for gemcitabine (P=0.029), vinorelbine (P=0.012), and docetaxel (P=0.009). The incidence of cases diagnosed as CD-DST-sensitive among the paired metastatic lesions was significantly lower than that for the primary lesions for vinorelbine (P=0.035) or docetaxel (P=0.022). The difference in the sensitivity to gemcitabine between the primary and paired non-lymphatic metastases was clearer than that between the primary lesion and paired lymph node metastases.

CONCLUSIONS

The sensitivities of the paired metastatic lesions to some anticancer drugs were significantly lower than those of the primary lesions. When performing chemotherapy based on CD-DST data using primary tumors from patients with postoperative recurrence, an appropriate regimen can be selected by carefully considering these differences.

Apoptosis related protein-1 triggers melanoma cell death via interaction with the juxtamembrane region of p75 neurotrophin receptor

Although chemotherapeutic drugs could theoretically target all metastatic sites, current treatments do not provide complementary therapeutics. Therefore, the development of an alternative approach replacing the traditional therapy is urgently needed. To assess the killing efficiency of the functionally identified apoptosis-related protein (APR)-1 in melanoma cells, we established a system for the regulated expression of APR-1. The induction of APR-1 expression caused apoptosis of melanoma cells via the interaction with the juxtamembrane region of p75 neurotrophin receptor (p75NTR), and possible also via the competition with tumour necrosis factor receptor-associated factor-6 (TRAF6) and the catalytic receptor of neurotrophin (Trk) for the same p75NTR interacting site. The accumulation of APR-1 in melanoma cells may block the physical association of p75NRT with TRAF6 and/or Trk, leading to the disruption of both NF-κB and extracellular signal-regulated kinase (ERK) pathways. Also, accumulation of APR-1 protein enhanced the activity of both c-Jun-N-terminal kinase (JNK) and p38 pathways. However, the analysis of APR-1-modulated pathways demonstrated the involvement of apoptosis-regulating kinase 1-JNK/p38 pathway in the induction of Bax expression leading to both mitochondrial dysregulation [as demonstrated by the loss of mitochondrial membrane potential, the release of both cytochrome c and apoptosis-inducing factor into cytoplasm, and cleavage of caspase-9, caspase-3 and poly (ADP-ribose) polymerase (PARP)] and endoplasmic reticulum stress as demonstrated by the increase of intracellular Ca(2+) release. Thus, besides the analysis of its pro-apoptotic function, our data provide insight into the molecular mechanism of APR-1-induced apoptosis of melanoma cells.

Apoptosis-related protein-2 triggers melanoma cell death by a mechanism including both endoplasmic reticulum stress and mitochondrial dysregulation

Metastatic cancers including melanoma are frequently associated with increased resistance to apoptosis induced by various therapeutic modalities, and the success of systemic therapy for the treatment of metastatic melanoma is minimal. In the present study, we demonstrated the ability of apoptosis-related protein (APR)-2 to trigger cell death via mechanism mediated by both endoplasmic reticulum (ER) stress [as evidenced by the increase of intracellular Ca(2+) release, the activation of both, inositol-requiring enzyme 1α (IRE1α) and calpain and cleavage of caspase-4] and mitochondrial dysregulation as evidenced by the loss of mitochondrial membrane potential, Cytochrome c release and cleavage of caspases-9 and -3, and poly adenosine diphosphate ribose polymerase (PARP). Also, the activation of apoptosis signal-regulating kinase (ASK) 1, c-jun-N-terminal kinase (JNK) and the transcription factors AP-1 and p53, and the induction of Bax expression were noted in APR-2-expressing cells. Both immune fluorescence staining and western blotting revealed the localization of APR-2 at ER and Bax protein at both mitochondria and ER. However, data of inhibitory experiments demonstrated that APR-2-induced apoptosis of melanoma cells is mediated by three parallel pathways: one of them IRE1/tumour necrosis factor receptor-associated factor 2/ASK1/JNK/Cyt.c/caspase-9/caspase-3/PARP) seems to be mitochondrial dependent, whereas, the other two pathways namely calpain/caspase-4/caspase-9/caspase-3/PARP and protein kinase RNA-like ER kinase/ATF4/C/EBP homologous protein (CHOP)/Bim seem to be mitochondrial independent. In conclusion, our data provide insight into the molecular mechanism of APR-2-induced apoptosis and suggest APR-2 gene transfer as an alternative approach for the treatment of chemoresistance melanoma metastasis.

Antimetastatic effects of Phyllanthus on human lung (A549) and breast (MCF-7) cancer cell lines

Background

Current chemotherapeutic drugs kill cancer cells mainly by inducing apoptosis. However, they become ineffective once cancer cell has the ability to metastasize, hence the poor prognosis and high mortality rate. Therefore, the purpose of this study was to evaluate the antimetastatic potential of Phyllanthus (P. niruri, P. urinaria, P. watsonii, and P. amarus) on lung and breast carcinoma cells.

Methodology/Principal Findings

Cytotoxicity of Phyllanthus plant extracts were first screened using the MTS reduction assay. They were shown to inhibit MCF-7 (breast carcinoma) and A549 (lung carcinoma) cells growth with IC₅₀ values ranging from 50–180 µg/ml and 65–470 µg/ml for methanolic and aqueous extracts respectively. In comparison, they have lower toxicity on normal cells with the cell viability percentage remaining above 50% when treated up to 1000 µg/ml for both extracts. After determining the non-toxic effective dose, several antimetastasis assays were carried out and Phyllanthus extracts were shown to effectively reduce invasion, migration, and adhesion of both MCF-7 and A549 cells in a dose-dependent manner, at concentrations ranging from 20–200 µg/ml for methanolic extracts and 50–500 µg/ml for aqueous extracts. This was followed by an evaluation of the possible modes of cell death that occurred along with the antimetastatic activity. Phyllanthus was shown to be capable of inducing apoptosis in conjunction with its antimetastastic action, with more than three fold increase of caspases-3 and -7, the presence of DNA-fragmentation and TUNEL-positive cells. The ability of Phyllanthus to exert antimetastatic activities is mostly associated to the presence of polyphenol compounds in its extracts.

Conclusions/Significance

The presence of polyphenol compounds in the Phyllanthus plant is critically important in the inhibition of the invasion, migration, and adhesion of cancer cells, along with the involvement of apoptosis induction. Hence, Phyllanthus could be a valuable candidate in the treatment of metastatic cancers.

Predicting and preventing melanoma invasiveness: advances in clarifying E2F1 function

Malignant melanoma of the skin is one of the most aggressive human cancers with increasing incidence, despite efforts to improve primary prevention. In particular, the prognosis of patients at late stages of the disease has not significantly improved in the last three decades, because systemic therapies have proven disappointing. Thus, metastatic melanoma continues to be a daunting clinical problem. The increasingly high rates of lethal outcome associated with advanced melanoma rely on the acquisition of invasiveness, early metastatic dissemination of tumor cells from their primary sites, and generation of chemoresistance as a consequence of alteration of key molecules involved in the regulation of cell survival. Thus far, extensive studies have been conducted to understand the molecular mechanisms that drive tumor progression, but the specific requirements underlying the aggressive behavior are still widely unknown. Understanding the determinants of this process is key to unveiling its dynamics, especially those that promote invasiveness, and may open new routes for the development of therapeutic strategies that control metastatic spread, and eventually the prevention of life-threatening metastases. Here, we review recent advances on molecular aspects, particularly of E2F1 transcription factor function, in the context of patient data, and discuss the implications for targeting melanoma cells when they begin to invade and metastasize.

Targeting cell spreading: a method of sensitizing metastatic tumor cells to TRAIL-induced apoptosis

TNF-related apoptosis-inducing ligand (TRAIL) is a current focus for the development of new cancer therapies, because of its selective induction of apoptosis in cancer cells. TRAIL has previously been shown to be important for tumor cell clearance from the liver; however, many cancer cell lines show some resistance toward TRAIL, posing a problem for the future use of TRAIL therapies. In this study, we show that interfering with a cell's ability to attach and spread onto a matrix can sensitize tumor cells to TRAIL-induced apoptosis in vitro. We targeted different members of the integrin signaling pathway using siRNA or inhibitors, including β-integrins, talin, Src, and downstream survival pathways PI3K and MAPK. Targeting any of these molecules could sensitize both MDA-MB-231 human breast cancer cells and TRAIL-resistant 1205Lu melanoma cells to TRAIL-induced apoptosis in vitro. Transcriptionally targeting the cytoskeleton, using myocardin-related transcription factor depletion to disrupt the transcription of cytoskeletal proteins, also caused TRAIL sensitization in MDA-MB-231 cells. We showed that this sensitivity to TRAIL correlated with increased activation of the intrinsic pathway of apoptosis. Manipulation of cell spreading therefore presents a potential method by which disseminated tumor cells could be sensitized to TRAIL therapies in vivo.

Is survivin the potential Achilles' heel of cancer?

Survivin, the smallest member of the inhibitors of apoptosis proteins (IAPs), plays an important role in the control of apoptosis, cell division, and cell migration/metastasis. Survivin is expressed and required for normal fetal development but is then generally no longer present in most adult tissues. However, reexpression of survivin is observed in numerous human cancers where presence of the protein is associated with enhanced proliferation, metastasis, poor prognosis, and decreased patient survival. Given the relatively selective expression in cancer cells, but not in normal tissue (tumor-associated antigen), and its importance in tumor cell biology, survivin has emerged as an attractive target for cancer treatment. Here, we discuss some aspects of survivin biology by focusing on why the protein appears to be so important for cancer cells and then discuss strategies that harness this dependence to eradicate tumors and situate survivin as a potential Achilles' heel of cancer.

Establishment of three cisplatin-resistant endometrial cancer cell lines using two methods of cisplatin exposure

Using the endometrial cancer cell line EI established in our department, we attempted to establish cisplatin (CDDP)-resistant cell lines by incremental exposure and high concentration exposure methods. Three CDDP-resistant cell lines were isolated, which could be distinguished by morphological differences. 1. Upon acquiring CDDP resistance, the cells tended to become small and grow in a floating state. This tendency was especially marked when using incremental exposure method. Using the incremental exposure method, a cell line obtained by isolating and culturing only adherent cells was designated EICR-Ia, and a cell line established by culturing only floating cells was designated EICR-If. A cell line obtained by the high concentration exposure method was designated EICR-II. 2. Upon acquiring CDDP resistance, tumor markers such as TPA and LDH increased, while proliferative capability of the cells was lowered. 3. The invasion capability was diminished in EICR-If cells, but was increased in EICR-Ia and EICR-II cells. 4. Following exposure to CDDP, the intracellular platinum concentrations were markedly elevated in EI and EICR-If cells, whereas the increase was mild in EICR-Ia and EICR-II cells and the concentration was lower than that in parent EI cells. 5. Studies of drug resistance gene expression revealed increased expression of MDR1, GSTπ, and Topo-II in EICR-If cells; increased expression of GSTπ in EICR-II cells; but no expression of any of the genes in EICR-Ia cells. 6. Analyses of cancer- and apoptosis-related genes showed increased expressions of Bcl-2, c-Myc, p53, and ICE in EICR-If cells. 7. Upon acquiring CDDP resistance, sensitivity to mitomycin and adriamycin decreased, but sensitivity to etoposide and 5-fluorouracil increased. The findings indicate that the mechanisms of CDDP resistance are different in the three cell lines.

Bioelectric applications for treatment of melanoma

Two new cancer therapies apply bioelectric principles. These methods target tumor structures locally and function by applying millisecond electric fields to deliver plasmid DNA encoding cytokines using electrogene transfer (EGT) or by applying rapid rise-time nanosecond pulsed electric fields (nsPEFs). EGT has been used to locally deliver cytokines such as IL-12 to activate an immune response, resulting in bystander effects. NsPEFs locally induce apoptosis-like effects and affect vascular networks, both promoting tumor demise and restoration of normal vascular homeostasis. EGT with IL-12 is in melanoma clinical trials and nsPEFs are used in models with B16F10 melanoma in vitro and in mice. Applications of bioelectrics, using conventional electroporation and extensions of it, provide effective alternative therapies for melanoma.

Immune surveillance of human cancer: if the cytotoxic T-lymphocytes play the music, does the tumoral system call the tune?

Accumulating evidence indicates that the innate and adaptive immune systems participate in the recognition and destruction of cancer cells by a process known as cancer immunosurveillance. Tumor antigen-specific cytotoxic T-lymphocytes (CTL) are the major effectors in the immune response against tumor cells. The identification of tumor-associated antigen (TAA) recognized primarily by CD 8(+) T-lymphocytes has led to the development of several vaccination strategies that induce or potentiate specific immune responses. However, large established tumors, which are associated with the acquisition of tumor resistance to specific lysis, are usually not fully controlled by the immune system. Recently, it has become clear that the immune system not only protects the host against tumor development but also sculpts the immunogenic phenotype of a developing tumor and can favor the emergence of resistant tumor cell variants. Moreover, it has become obvious that the evasion of immunosurveillance by tumor cells is under the control of the tumor microenvironment complexity and plasticity. In this review, we will focus on some new mechanisms associated with the acquisition of tumor resistance to specific lysis during tumor progression, involving genetic instability, structural changes in cytoskeleton, and hypoxic stress. We will also discuss the interaction between CTLs and tumor endothelial cells, a major component of tumor stroma.

Evaluation of survivin as a prognostic marker in oral squamous cell carcinoma

BACKGROUND

Poor prognosis of oral squamous cell carcinoma (OSCC) is partly attributed to the lack of significant tumor marker for accurate staging and prognostication. We have evaluated survivin, which is a member of the inhibitor of apoptosis family as a cancer marker associated with proliferation, angiogenesis, oral carcinogenesis, and OSCC patient survival, as we reported a prognostic significance of survivin expression in lymph node previously.

METHODS

To evaluate survivin expression in six OSCC cell lines, Western blotting was performed. Hamster oral carcinogenesis model was used to observe changes of survivin expression in oral carcinogenesis. Finally, we assessed the diagnostic and prognostic significance of survivin in a series of 38 primary OSCC through immunohistochemistry (CD31, PCNA) and Kaplan-Meier's test.

RESULTS

Survivin expression was detected in all OSCC cell lines at a varying level but not observed in normal gingival keratinocyte cells. In hamster model, survivin expression was observed from 8 weeks through 16 weeks and the intensity of expression became strong until 16 weeks. Clinicopathological analysis revealed a significant correlation between survivin expression and lymph node metastasis (P = 0.006) and proliferation (P < 0.001). However, there was no significant relationship with differentiation, micro vessel density, and cancer stage based on TNM. Survivin overexpression had a significant negative effect on survival of patients.

CONCLUSIONS

These results demonstrate the significant relationship between survivin expression and oral carcinogenesis and aggressiveness of OSCC including survival rate of patient. Survivin therefore may be used as a significant cancer marker to gain prognostic information of OSCC.

3-O-methylfunicone, a metabolite of Penicillium pinophilum, inhibits proliferation of human melanoma cells by causing G(2) + M arrest and inducing apoptosis

OBJECTIVES

Melanoma cells take advantage of impaired ability to undergo programmed cell death in response to different external stimuli and chemotherapeutic drugs; this makes prevention of tumour progression very difficult. The aim of this study was to demonstrate whether 3-O-methylfunicone (OMF), a metabolite of Penicillium pinophilum, has the ability to arrest cell population growth and to induce apoptosis in A375P (parental) and A375M (metastasis derivatived) melanoma cell lines.

MATERIALS AND METHODS

Cell proliferation and apoptosis were analysed by flow cytometry, DNA fragmentation, caspase-3 and caspase-9 activation, and PARP-1 cleavage.

RESULTS

We demonstrated that OMF affected cell proliferation in a time- and dose-dependent manner, reaching the best effect at concentration of 80 microg/ml for 24 h. Flow cytometry revealed that OMF caused significant G(2) phase arrest, which was associated with marked decrease in cyclin B1/p34(cdc2) complex and p21 induction. OMF also induced marked decrease of survivin expression. Reduced levels of apoptosis were evident after silencing p21 expression in both cell lines. Finally, the effect exercised by OMF on hTERT and TEP-1 gene expression confirmed the ability of this molecule to interfere with replicative ability of cells.

CONCLUSIONS

The results reported here seem to suggest that OMF as a promising molecule to include in strategies for treatment of melanoma.

Connective tissue growth factor confers drug resistance in breast cancer through concomitant up-regulation of Bcl-xL and cIAP1

Connective tissue growth factor (CTGF) expression is elevated in advanced breast cancer and promotes metastasis. Chemotherapy response is only transient in most metastatic diseases. In the present study, we examined whether CTGF expression could confer drug resistance in human breast cancer. In breast cancer patients who received neoadjuvant chemotherapy, CTGF expression was inversely associated with chemotherapy response. Overexpression of CTGF in MCF7 cells (MCF7/CTGF) enhanced clonogenic ability, cell viability, and resistance to apoptosis on exposure to doxorubicin and paclitaxel. Reducing the CTGF level in MDA-MB-231 (MDA231) cells by antisense CTGF cDNA (MDA231/AS cells) mitigated this drug resistance capacity. CTGF overexpression resulted in resistance to doxorubicin- and paclitaxel-induced apoptosis by up-regulation of Bcl-xL and cellular inhibitor of apoptosis protein 1 (cIAP1). Knockdown of Bcl-xL or cIAP1 with specific small interfering RNAs abolished the CTGF-mediated resistance to apoptosis induced by the chemotherapeutic agents in MCF7/CTGF cells. Inhibition of extracellular signal-regulated kinase (ERK)-1/2 effectively reversed the resistance to apoptosis as well as the up-regulation of Bcl-xL and cIAP1 in MCF7/CTGF cells. A neutralizing antibody against integrin alpha(v)beta(3) significantly attenuated CTGF-mediated ERK1/2 activation and up-regulation of Bcl-xL and cIAP1, indicating that the integrin alpha(v)beta(3)/ERK1/2 signaling pathway is essential for CTGF functions. The Bcl-xL level also correlated with the CTGF level in breast cancer patients. We also found that a COOH-terminal domain peptide from CTGF could exert activities similar to full-length CTGF, in activation of ERK1/2, up-regulation of Bcl-xL/cIAP1, and resistance to apoptosis. We conclude that CTGF expression could confer resistance to chemotherapeutic agents through augmenting a survival pathway through ERK1/2-dependent Bcl-xL/cIAP1 up-regulation.

Knockdown of Ron kinase inhibits mutant phosphatidylinositol 3-kinase and reduces metastasis in human colon carcinoma

Abnormal accumulation and activation of receptor tyrosine kinase Ron (recepteur d'origine nantais) has been demonstrated in a variety of primary human cancers. We show that RNA interference-mediated knockdown of Ron kinase in a highly tumorigenic colon cancer cell line led to reduced proliferation as compared with the control cells. Decreased Ron expression sensitized HCT116 cells to growth factor deprivation stress-induced apoptosis as reflected by increased DNA fragmentation and caspase 3 activation. In addition, cell motility was decreased in Ron knockdown cells as measured by wound healing assays and transwell assays. HCT116 cells are heterozygous for gain of function mutant PIK3CA H1047R. Analysis of signaling proteins that are affected by Ron knockdown revealed that phosphatidylinositol 3-kinase (PI3K) activity of the mutant PI3K as well as AKT phosphorylation was substantially reduced in the Ron knockdown cells compared with the control cells. Moreover, we demonstrated in vivo that knockdown of Ron expression significantly reduced lung metastasis as compared with the control cells in the orthotopic models. In summary, our results demonstrate that Ron plays an essential role in maintaining malignant phenotypes of colon cancer cells through regulating mutant PI3K activity. Therefore, targeting Ron kinase could be a potential strategy for colon cancer treatment, especially in patients bearing gain of function mutant PI3K activity.

ICAM-1 has a critical role in the regulation of metastatic melanoma tumor susceptibility to CTL lysis by interfering with PI3K/AKT pathway

Human primary melanoma cells (T1) were found to be more susceptible to lysis by a Melan-A/MART-1-specific CTL clone (LT12) than their metastatic derivative (G1). We show that this differential susceptibility does not involve antigen presentation by target cells, synapse formation between the metastatic target and CTL clone, or subsequent granzyme B (GrB) polarization. Although PI-9, an inhibitor of GrB, was found to be overexpressed in metastatic G1 cells, knockdown of the PI-9 gene did not result in the attenuation of G1 resistance to CTL-induced killing. Interestingly, we show that whereas T1 cells express high levels of intercellular adhesion molecule-1 (ICAM-1), a dramatically reduced expression was noted on G1 cells. We also showed that sorted ICAM-1+ G1 cells were highly sensitive to CTL-induced lysis compared with ICAM-1- G1 cells. Furthermore, incubation of metastatic G1 cells with IFN-gamma resulted in the induction of ICAM-1 and the potentiation of their susceptibility to lysis by LT12. More importantly, we found that the level of ICAM-1 expression by melanoma cells correlated with decreased PTEN activity. ICAM-1 knockdown in T1 cells resulted in increased phosphorylation of PTEN and the subsequent activation of AKT. We have additionally shown that inhibition of the phosphatidylinositol (3,4,5)-triphosphate kinase (PI3K)/AKT pathway by the specific inhibitor wortmannin induced a significant potentiation of susceptibility of G1 and ICAM-1 small interfering RNA-treated T1 cells to CTL-induced lysis. The present study shows that a shift in ICAM-1 expression, which was associated with an activation of the PI3K/AKT pathway, can be used by metastatic melanoma cells to escape CTL-mediated killing.

Survivin expression in renal cell carcinoma

Deregulated expression of inhibitors of apoptosis may contribute to cancer by aberrantly extending cell viability and facilitating the insurgence of resistance to chemo- and radiotherapy. In this study, we have investigated, by immunohistochemical technique, the expression and potential prognostic significance of survivin in a series of 49 clear cell type renal cell carcinoma (ccRCC). Survivin expression was significantly associated with poorly differentiated, advanced stages and more aggressive ccRCCs (p < 0.05). Patients with low survivin expression had statistically significant better survival rates than patients with high survivin expression (p < 0.05). This may be relevant for follow-up protocols design and/or alternative therapeutic approaches.

Malignant melanoma in the 21st century: the emerging molecular landscape

Malignant melanoma presents a substantial clinical challenge. Current diagnostic methods are limited in their ability to diagnose early disease and accurately predict individual risk of disease progression and outcome. The lack of adequate approaches to properly define disease subgroups precludes rational treatment design and selection. Better tools are urgently needed to provide more accurate and personalized melanoma patient management. Recent progress in the understanding of the molecular aberrations that underlie melanoma oncogenesis will likely advance the diagnosis, prognosis, and treatment of melanoma. The emerging pattern of molecular complexity in melanoma tumors mirrors the clinical diversity of the disease and highlights the notion that melanoma, like other cancers, is not a single disease but a heterogeneous group of disorders that arise from complex molecular changes. Understanding of molecular aberrations involving important cellular processes, such as cellular signaling networks, cell cycle regulation, and cell death, will be essential for better diagnosis, accurate assessment of prognosis, and rational design of effective therapeutics. Defining an individual patient's unique tumor characteristics may lead to personalized prediction of outcomes and selection of therapy. We review the emerging molecular landscape of melanoma and its implications for better management of patients with melanoma.

PINCH-1 regulates the ERK-Bim pathway and contributes to apoptosis resistance in cancer cells

Resistance to apoptosis is a hallmark of cancer cells. We report here that PINCH-1, a cytoplasmic component of cell-extracellular matrix adhesions, is required for protection of multiple types of cancer cells from apoptosis. Furthermore, using HT-1080 fibrosarcoma cells as a model system, we have investigated the signaling pathway through which PINCH-1 contributes to apoptosis resistance. Loss of PINCH-1 markedly increases the level of Bim and promotes Bim translocation to mitochondria, resulting in activation of the intrinsic apoptosis pathway. Depletion of Bim completely blocked apoptosis induced by the loss of PINCH-1. Thus, PINCH-1 contributes to apoptosis resistance through suppression of Bim. Mechanistically, PINCH-1 suppresses Bim not only transcriptionally but also post-transcriptionally. PINCH-1 promotes activating phosphorylation of Src family kinase and ERK1/2. Consistent with this, ERK1/2-mediated Ser(69) phosphorylation of Bim, a key signal for turnover of Bim, is suppressed by the removal of PINCH-1. Our results demonstrate a strong dependence of multiple types of apoptosis-resistant cancer cells on PINCH-1 and provide new insights into the molecular mechanism by which cancer cells are protected from apoptosis.

Mutant PIK3CA-bearing colon cancer cells display increased metastasis in an orthotopic model

Mutations in the PIK3CA gene are common in human cancers, including colon cancer. We compared two pairs of colon cancer cells (HCT116 and DLD1) bearing only the wild-type (WT) or mutant (MUT) PIK3CA allele for their survival capacity under stress conditions in vitro as well as their metastatic properties in an in vivo orthotopic model. When subjected to growth factor deprivation stress (GFDS), the MUT PIK3CA cells displayed resistance to GFDS-induced apoptosis relative to the WT cells. Phosphatidylinositol 3-kinase (PI3K) and its downstream effector AKT were constitutively activated during stress conditions in the MUT PIK3CA cells but not in the WT cells. The MUT cells showed hypersensitivity to PI3K inhibition. Moreover, the proapoptotic protein Bax was expressed at a very high level in the WT PIK3CA cells, whereas it was almost undetectable in the MUT cells. Inhibition of Bax expression by small interfering RNA protected the WT PIK3CA cells from GFDS-induced apoptosis, suggesting an important role of Bax in GFDS-induced apoptosis. These results indicated that the MUT PI3K confers resistance to GFDS-induced apoptosis and that the MUT cells are more dependent on the PI3K pathway for survival. In vivo studies showed that the MUT PIK3CA-bearing cells were more metastatic than the WT cells in an orthotopic model of colon cancer. Taken together, these results suggest that MUT PI3K imparts a more aggressive phenotype in colon cancer cells and could be a potential therapeutic target for treatment of colon cancer patients bearing PIK3CA mutations.

A Chemical Screen Identifies Anisomycin as an Anoikis Sensitizer That Functions by Decreasing FLIP Protein Synthesis

Malignant epithelial cells with metastatic potential resist apoptosis that normally occurs upon loss of anchorage from the extracellular matrix, a process termed "anoikis." Resistance to anoikis enables malignant cells to survive in an anchorage-independent manner, which leads to the formation of distant metastases. To understand the regulation of anoikis, we designed, automated, and conducted a high-throughput chemical screen for anoikis sensitizers. PPC-1 anoikis-resistant prostate cancer cells were seeded in hydrogel-coated ultralow binding plates for suspension conditions and standard tissue culture plates to promote adhesion. After seeding, cells were treated with aliquots from a library of previously characterized small molecules, and viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt, assay. From this chemical screen, we identified anisomycin that induced apoptosis in suspension conditions, but was not toxic to these cells grown under adherent conditions. Anisomycin sensitized cells to anoikis by decreasing levels of the caspase-8 inhibitor FLIP and subsequently activating the death receptor pathway of caspase activation. Although anisomycin activated c-Jun-NH(2)-kinase and p38, these kinases were not functionally important for the effect of anisomycin on anoikis and FLIP. Rather, anisomycin decreased FLIP and sensitized cells to anoikis by inhibiting its protein synthesis. Finally, we showed that anisomycin decreased distal tumor formation in a mouse model of prostate cancer metastases. Thus, a novel chemical screen identified anisomycin as an anoikis sensitizer that acts by decreasing FLIP protein synthesis. Our results suggest that FLIP is a suppressor of anoikis and inhibiting FLIP protein synthesis may be a useful antimetastatic strategy.

Critical role for Fas-associated death domain-like interleukin-1-converting enzyme-like inhibitory protein in anoikis resistance and distant tumor formation

BACKGROUND

Normal epithelial cells undergo anoikis, or apoptosis on loss of anchorage to the extracellular matrix, by initiating the death receptor pathway of caspase activation. However, malignant epithelial cells with metastatic potential resist anoikis and can survive in an anchorage-independent fashion. We hypothesized that c-Fas-associated death domain-like interleukin-1-converting enzyme-like inhibitory protein (FLIP), an endogenous inhibitor of death receptor signaling, may suppress anoikis.

METHODS

We assessed viability and apoptosis of PPC-1 prostate cancer cells cultured in adherent and suspension conditions using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt and Annexin V staining assays. Expression of the death receptor Fas and activation of caspase 8 were measured using flow cytometry. Expression of Fas ligand was measured by reverse transcription-polymerase chain reaction. FLIP protein expression was measured by immunoblotting. Small-molecule inhibitors of FLIP (including the death receptor sensitizer 5809354) and small-interfering (si) RNA directed against FLIP were used to assess the effects of FLIP inhibition on anoikis of prostate cancer cells in vitro and in vivo. All statistical tests were two-sided.

RESULTS

PPC-1 cells cultured in suspension resisted anoikis, despite increased expression of Fas (0 versus 8 hours, mean relative percent expression = 100% versus 135%, difference = 35%, 95% confidence interval [CI] = 10% to 61%; P = .02) and Fas L (0 versus 24 hours, mean relative percent expression = 100% versus 208%, difference = 108%, 95% CI = 18% to 197%; P = .02). Knockdown of FLIP expression by siRNA or treatment with 5809354 sensitized prostate cancer cells to anoikis (control siRNA versus FLIP siRNA at 10 nM, mean relative percent viability = 95% versus 51%, difference = 44%, 95% CI = 34% to 54%; P<.001; control versus 5809354 at 20 microM, mean relative percent viability = 96% versus 52%, difference = 44%, 95% CI = 13% to 75%; P = .015). Inhibition of FLIP expression specifically activated caspase 8 in PPC-1 cells grown in suspension but not adherent conditions and decreased the metastatic potential of circulating PPC-1 cells in vivo.

CONCLUSIONS

FLIP may be a suppressor of anoikis and therefore a possible target for antimetastatic therapeutic strategies.

Intravascular cell-to-cell adhesive interactions and bone metastasis

Metastatic cancer spread to bones, causing intractable pain, pathological fractures, spinal cord compression, and ultimately death, represents massive clinical problem. Intravascular cell-to-cell heterotypic (between cancer and other types of cells) and homotypic (between cancer cells) adhesive interactions, leading to the establishment of metastatic deposits in bone marrow vasculature, represent important rate-limiting steps in bone metastasis. In this review, we discuss molecular and cellular mechanisms underpinning metastasis-associated intravascular cell-to-cell adhesive interactions, their role in a multi-step metastatic cascade, and a potential for therapeutic targeting of early metastasis-associated adhesive events.

HRPAP20: a novel calmodulin-binding protein that increases breast cancer cell invasion

We previously reported the identification of HRPAP20 (hormone-regulated proliferation-associated protein 20), a novel hormone-regulated, proliferation-associated protein. In tumor cell lines, constitutive HRPAP20 expression enhanced proliferation and suppressed apoptosis, characteristics frequently associated with malignant progression. Here, we report that highly invasive breast cancer cell lines and human breast tumor specimens express elevated HRPAP20, which in transfection experiments in MCF-7 and MDA-MB-231 cells, increased invasion. Results from mechanistic studies revealed that HRPAP20 bound to calmodulin (CaM) via a conserved CaM-binding motif. Transfection of MCF-7 breast cancer cells with HRPAP20 harboring a mutated CaM-binding motif (HRPAP20K73A) inhibited its interaction with CaM and failed to increase invasion. Other experiments revealed that transfection with HRPAP20, but not HRPAP20K73A, increased secretion of matrix metalloproteinase-9 (MMP-9). Moreover, knockdown of HRPAP20 with small interfering RNA in MCF-7/HRPAP20 transfectants and wild-type MDA-MB-231 cells reduced invasion and inhibited secretion of MMP-9. Together these observations suggest that HRPAP20 may be an important regulator of breast tumor cell invasion by a CaM-mediated mechanism that leads to increased MMP-9 secretion. We conclude that dysregulation of HRPAP20 expression in tumor cells may contribute to the observed phenotypic changes associated with breast cancer progression.

Malignant melanoma: genetics and therapeutics in the genomic era

Cell for cell, probably no human cancer is as aggressive as melanoma. It is among a handful of cancers whose dimensions are reported in millimeters. Tumor thickness approaching 4 mm presents a high risk of metastasis, and a diagnosis of metastatic melanoma carries with it an abysmal median survival of 6-9 mo. What features of this malignancy account for such aggressive behavior? Is it the migratory history of its cell of origin or the programmed adaptation of its differentiated progeny to environmental stress, particularly ultraviolet radiation? While the answers to these questions are far from complete, major strides have been made in our understanding of the cellular, molecular, and genetic underpinnings of melanoma. More importantly, these discoveries carry profound implications for the development of therapies focused directly at the molecular engines driving melanoma, suggesting that we may have reached the brink of an unprecedented opportunity to translate basic science into clinical advances. In this review, we attempt to summarize our current understanding of the genetics and biology of this disease, drawing from expanding genomic information and lessons from development and genetically engineered mouse models. In addition, we look forward toward how these new insights will impact on therapeutic options for metastatic melanoma in the near future.

Targeted apoptosis activation with GrB/scFvMEL modulates melanoma growth, metastatic spread, chemosensitivity, and radiosensitivity

GrB/scFvMEL, a fusion protein composed of human granzyme B (GrB) and the single-chain antibody scFvMEL, targets melanoma gp240 antigen and exerts impressive cytotoxic effects by inducing apoptosis. We evaluated the effects of GrB/scFvMEL on chemotherapy, radiation therapy, metastasis in vitro, and the growth of human melanoma A375 xenograft tumors in nude mice. GrB/scFvMEL showed synergistic cytotoxicity when coadministered with doxorubicin, vincristine or cisplatin, and additive effects, in combination with etoposide or cytarabine. Optimal cytotoxic effects were obtained when cells were treated first with GrB/scFvMEL followed by exposure to the agent (rather than the reverse). Pretreatment of A375 cells with GrB/scFvMEL significantly sensitized melanoma cells to ionizing radiation assessed using a clonogenic survival assay. Subtoxic doses of GrB/scFvMEL inhibited the invasion of A375 cells into Matrigel. GrB/scFvMEL (37.5 mg/kg) was administered intravenously to nude mice bearing A375 tumors. Saline-treated tumors increased 24-fold, whereas tumors treated with GrB/scFvMEL showed a significant tumor growth delay increasing four-fold. Tumor tissue displayed an increase in apoptotic nuclei compared to control. Thus, the targeted delivery of GrB to tumors may have a significant potential for cancer treatment. Targeted therapeutic agents specifically designed to impact cellular apoptotic pathways may represent a novel class of therapeutic agents.

Metastasis: a question of life or death

The metastatic process is highly inefficient--very few of the many cells that migrate from the primary tumour successfully colonize distant sites. One proposed mechanism to explain this inefficiency is provided by the cancer stem cell model, which hypothesizes that micrometastases can only be established by tumour stem cells, which are few in number. However, recent in vitro and in vivo observations indicate that apoptosis is an important process regulating metastasis. Here we stress that the inhibition of cell death, apart from its extensively described function in primary tumour development, is a crucial characteristic of metastatic cancer cells.

Activation of dual apoptotic pathways in human melanocytes and protection by survivin

Apoptosis resistance in melanoma is a primary cause of treatment failure. Apoptotic pathways in melanocytes, from which melanoma arises, are poorly characterized. Human melanocytes were susceptible to apoptosis following exposure to UV radiation (UVB, 24-48 hours), 4-tert-butylphenol (4-TBP, 1-4 hours), and cisplatin (24-48 hours). These responses were associated with Bid cleavage, caspase activation (caspases 3, 8, and 9), mitochondrial depolarization and release of cytochrome c, Smac/DIABLO, and apoptosis-inducing factor (AIF), but not endonuclease G. The apoptotic responses and AIF release were caspase-independent, as they were not blocked by zVal-Ala-Asp(OMe)-fluoromethyl ketone (zVAD-fmk). While RNA interference-mediated knockdown of AIF protected melanocytes against apoptosis induced by serum withdrawal, apoptotic responses to UVB, cisplatin, and 4-TBP were not compromised by AIF knockdown, even in the presence of zVAD-fmk. Finally, adenoviral-mediated expression of Survivin, an inhibitor of apoptosis expressed in melanoma but not melanocytes, protected melanocytes against UVB-induced apoptosis. Survivin expression in melanocytes partially blocked caspase activation and release of mitochondrial release of AIF, cytochrome c, and Smac induced by UVB. These data indicate that multiple stimuli can activate both caspase-dependent and caspase-independent apoptotic pathways in melanocytes, and that endogenous expression of Survivin in melanoma may contribute to apoptosis resistance by multiple mechanisms.