Tumor metastasis: moving new biological insights into the clinic

IR-780-loaded polymeric micelles enhance the efficacy of photothermal therapy in treating breast cancer lymphatic metastasis in mice

Cancer metastasis is responsible for over 90% of breast cancer-related deaths, and inhibiting lymph node metastasis is an option to treat metastatic disease. Herein, we report the use of IR-780-loaded polymeric micelles (IPMs) for effective photothermal therapy (PTT) of breast cancer lymphatic metastasis. The IPMs were nanometer-sized micelles with a mean diameter of 25.6 nm and had good stability in simulated physiological solutions. Under 808-nm laser irradiation, IPMs exhibited high heat-generating capability in both in vitro and in vivo experiments. After intravenous injection, IPMs specifically accumulated in the tumor and metastatic lymph nodes and penetrated into these tissues. Moreover, a single IPMs treatment plus laser irradiation significantly inhibited primary tumor growth and suppressed lymphatic metastasis by 88.2%. Therefore, IPMs are an encouraging platform for PTT applications in treatment of metastatic breast cancer.

Associations between the Epithelial-Mesenchymal Transition Phenotypes of Circulating Tumor Cells and the Clinicopathological Features of Patients with Colorectal Cancer

In this study, we identified CTCs using the previously reported CanPatrol CTC enrichment technique from peripheral blood samples of 126 patients with colorectal cancer (CRC) and found that CTCs could be classified into three subpopulations based on expression of epithelial cell adhesion molecule (EpCAM) (E-CTCs), the mesenchymal cell marker vimentin (M-CTCs), or both EpCAM and vimentin (biphenotypic E/M-CTCs). Circulating tumor microemboli (CTMs) were also identified in peripheral blood samples. Meanwhile, E-CTCs, M-CTCs, E/M-CTCs, and CTMs were detected in 76.98%, 42.06%, 56.35%, and 36.51% of the 126 patients, respectively. Interestingly, the presence of CTMs and each CTC subpopulation was significantly associated with blood lymphocyte counts and tumor-node-metastasis stage (P < 0.001). Lymphocyte counts and the neutrophil-to-lymphocyte ratio (NLR) in patients lacking CTCs were significantly different from those in patients testing positive for CTMs and each CTC subpopulation (P < 0.001). Our results indicate that tumor metastasis is more significantly associated with the presence of CTMs and M-CTCs than with other CTC subpopulations and suggest that EMT may be involved in CTC evasion of lymphocyte-mediated clearance.

CRP2, a new invadopodia actin bundling factor critically promotes breast cancer cell invasion and metastasis

A critical process underlying cancer metastasis is the acquisition by tumor cells of an invasive phenotype. At the subcellular level, invasion is facilitated by actin-rich protrusions termed invadopodia, which direct extracellular matrix (ECM) degradation. Here, we report the identification of a new cytoskeletal component of breast cancer cell invadopodia, namely cysteine-rich protein 2 (CRP2). We found that CRP2 was not or only weakly expressed in epithelial breast cancer cells whereas it was up-regulated in mesenchymal/invasive breast cancer cells. In addition, high expression of the CRP2 encoding gene CSRP2 was associated with significantly increased risk of metastasis in basal-like breast cancer patients. CRP2 knockdown significantly reduced the invasive potential of aggressive breast cancer cells, whereas it did not impair 2D cell migration. In keeping with this, CRP2-depleted breast cancer cells exhibited a reduced capacity to promote ECM degradation, and to secrete and express MMP-9, a matrix metalloproteinase repeatedly associated with cancer progression and metastasis. In turn, ectopic expression of CRP2 in weakly invasive cells was sufficient to stimulate cell invasion. Both GFP-fused and endogenous CRP2 localized to the extended actin core of invadopodia, a structure primarily made of actin bundles. Purified recombinant CRP2 autonomously crosslinked actin filaments into thick bundles, suggesting that CRP2 contributes to the formation/maintenance of the actin core. Finally, CRP2 depletion significantly reduced the incidence of lung metastatic lesions in two xenograft mouse models of breast cancer. Collectively, our data identify CRP2 as a new cytoskeletal component of invadopodia that critically promotes breast cancer cell invasion and metastasis.

Dual Functions of Cyclometalated Iridium(III) Complexes: Anti-Metastasis and Lysosome-Damaged Photodynamic Therapy

Four phosphorescent cyclometalated iridium(III) complexes containing benzimidazole moiety have been designed and synthesized. These Ir(III) complexes can effectively inhibit several cancerous processes, including cell migration, invasion, colony formation, and angiogenesis. Interestingly, they show a much higher singlet oxygen quantum yield in an acidic solution than in a neutral solution. Upon irradiation at 425 nm with low energy (1.2 J cm^-2), they can induce apoptosis through lysosomal damage, evaluation of reactive oxygen species level, and activation of caspase-3/7. The highest phototoxicity index is >476, with almost no dark cytotoxicity observed for Ir4. Ir4 can also inhibit tumor growth effectively in nude mice in vivo after photodynamic therapy. An in vitro assay against 70 kinases indicates that maternal embryonic leucine zipper kinase (MELK), PIK3CA, and AMPK are the possible molecular targets. The half maximal inhibitory concentration of Ir4 toward MELK is 1.27 μM. Our study demonstrates that these Ir(III) complexes are promising anticancer agents with dual functions, including metastasis inhibition and lysosome-damaged photodynamic therapy.

Domesticating Cancer: An Evolutionary Strategy in the War on Cancer

Since cancer shares the same molecular machinery as the host, most therapeutic interventions that aim to target cancer would inadvertently also adversely affect the host. In addition, cancer continuously evolves, streamlining its host-derived genome for a new single-celled existence. In particular, short-term clinical success observed with most antineoplastic therapies directly relate to the fact that cancer is constantly evolving. However, the clonal evolution of cancer occasionally also render cancer cells uniquely susceptible to therapeutic interventions, as is exemplified by the clinical relevance of synthetic lethality. Synthetic lethality describes a situation where the simultaneous loss of function in two genes results in lethality, but where a loss of function in either single gene is tolerated. This observation suggests that the evolution of cancer, usually seen as a major clinical challenge, may also afford a key opportunity in lowering on-target toxicities accosted with chemotherapy. As an example, by subjecting cancer to specific selection regimes, cancer can in effect be placed on evolutionary trajectories leading to the development of “targetable” phenotypes such as synthetic lethal interactions. However, such a selection regime would have to overcome a range of obstacles such as on-target toxicity and the selection of an evolvable trait. Since the majority of cancer evolution manifests as a loss of function, we suggest that the induction of auxotrophic phenotypes (i.e., where an organism lose the ability to synthesize specific organic compounds required for growth and thus become dependent on it from dietary sources) may represent an attractive therapeutic option. As an example, animals can obtain vitamin C either by de novo synthesis or from their diet. However, since the maintenance of synthetic pathways is costly, such pathways are often lost if no longer necessary, resulting in the organism being auxotrophic toward the dietary compound. Similarly, increasing the maintenance cost of a redundant pathway in cancer cells is likely to select for clones that have lost such a redundant pathway. Inhibition of a pathway, while supporting the activity of a compensating pathway, may thus induce auxotrophism in cancer cells but not in genomic stable host cells.

Blood cadmium levels associated with short distant metastasis-free survival time in invasive breast cancer

Distant metastasis is strongly associated with poor prognosis of breast cancer. Cadmium (Cd) exposure was previously found associated with breast cancer incidence. We explored the associations of blood cadmium levels (BCLs) and clinicopathologic characteristics with invasive breast cancer distant metastasis. Blood samples were collected and analyzed for BCLs by graphite-furnace atomic absorption spectrometry. Clinicopathologic characteristics, including basic clinical information and tumor characteristics, were obtained from medical records. Breast cancer distant metastasis-free survival (DMFS) time was calculated at follow-up. The associations of BCLs and clinicopathologic characteristics with DMFS time were examined by Kaplan-Meier method and Cox regression analysis, and associations between BCLs and tumor characteristics were also explored. Blood Cd level was positively associated with distant metastasis, clinical stage, BMI, and age. On univariate analysis, older age at diagnosis, family history of breast cancer, high N classification and clinical stage, positivity for human epidermal growth factor receptor 2, and high BCLs were associated with short DMFS time. On multivariate analysis model, older age at diagnosis, family history of breast cancer, high N classification, and BCLs were predictors for breast cancer distant metastasis. BCLs were a risk factor for short DMFS time of invasive breast cancer. BCLs and some clinicopathologic factors affect breast cancer distant metastasis, which needs further epidemiological and experimental studies to confirm.

A distinct serum metabolic signature of distant metastatic papillary thyroid carcinoma

BACKGROUND

Although the incidence rate for thyroid cancer seems to have begun stabilizing in recent years, an increased rate of advanced stage of this disease has been reported. Additionally, distant metastasis is one of the most important prognostic factors of patients with papillary thyroid carcinoma (PTC). Unfortunately, the underlying mechanisms of distant metastasis, as well as cell status like metabolism changes in distant metastatic tumours have not been clearly elucidated.

OBJECTIVE

To identify serum metabolic signature of distant metastatic PTC.

DESIGN, PATIENTS AND MEASUREMENTS

In this study, gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) was used to analyse the serum from 77 patients diagnosed with PTC (37 in distant metastasis group and 40 in ablation group). Principal component analysis (PCA) and orthogonal partial least-squares-discriminant analysis (OPLS-DA) scores plots were used to analyse the data.

RESULTS

Principal component analysis and OPLS-DA analyses demonstrated an evident trend of separation between 40 serum samples from the ablation group and 37 samples from distant metastasis group. A total of 31 metabolites were identified, which are related to amino acid, lipid, glucose, vitamin metabolism and diet/gut microbiota interaction. Pathway analysis showed "alanine, aspartate and glutamate metabolism" and "inositol phosphate metabolism" were the most relevant pathways.

CONCLUSION

Serum metabolomics profiling could significantly discriminate papillary thyroid cancer patients according to distant metastasis. Potential metabolic aberration in distant metastatic PTC could be involved in different biological behaviours of tumour cells including proliferation, invasion/migration and immune escape. Diet/gut microbiota-produced metabolites could play an important role in these effects. This work may provide new clues to find the underlying mechanisms regarding the distant metastasis of PTC as well as potential adjuvant therapy targets.

Co-delivery of docetaxel and silibinin using pH-sensitive micelles improves therapy of metastatic breast cancer

Breast cancer is the most vicious killer for women, and tumor metastasis is one of the leading causes of breast cancer therapy failure. In this study, a new pH-sensitive polymer (polyethylene glycol-block-poly[(1,4-butanediol)-diacrylate-β-N,N-diisopropylethylenediamine], BDP) was synthesized. Based on BDP, docetaxel/silibinin co-delivery micelles (DSMs) was constructed. DSM had a well-defined spherical shape under the transmission electron microscope with average hydrodynamic diameter of 85.3±0.4 nm, and were stable in the bloodstream but could dissociate to release the chemotherapeutic agents in the low pH environment of the endo/lysosomes in the tumor cells. Compared with free drugs, DSM displayed greatly enhanced cellular uptake, higher cytotoxicity and a stronger anti-metastasis effect against mouse breast cancer cell line 4T1. In 4T1 tumor-bearing mice treated with DSM (twice a week for 3 weeks), the inhibition rate on tumor growth and metastasis reached 71.9% and 80.1%, respectively. These results reveal that DSM might be a promising drug delivery system for metastatic breast cancer therapy.

Parkin targets HIF-1α for ubiquitination and degradation to inhibit breast tumor progression

Mutations in E3 ubiquitin ligase Parkin have been linked to familial Parkinson’s disease. Accumulating evidence suggests that Parkin is a tumor suppressor, but the underlying mechanism is poorly understood. Here we show that Parkin is an E3 ubiquitin ligase for hypoxia-inducible factor 1α (HIF-1α). Parkin interacts with HIF-1α and promotes HIF-1α degradation through ubiquitination, which in turn inhibits metastasis of breast cancer cells. Parkin downregulation in breast cancer cells promotes metastasis, which can be inhibited by targeting HIF-1α with RNA interference or the small-molecule inhibitor YC-1. We further identify lysine 477 (K477) of HIF-1α as a major ubiquitination site for Parkin. K477R HIF-1α mutation and specific cancer-associated Parkin mutations largely abolish the functions of Parkin to ubiquitinate HIF-1α and inhibit cancer metastasis. Importantly, Parkin expression is inversely correlated with HIF-1α expression and metastasis in breast cancer. Our results reveal an important mechanism for Parkin in tumor suppression and HIF-1α regulation.

Parkin is an E3 ubiquitin ligase involved in Parkinson’s disease. Parkin has also been linked to cancer suppression but the mechanisms are unclear. Here the authors show that Parkin regulates HIF-1α through ubiquitin-dependent degradation, thus inhibiting metastasis of breast cancer cells.

Beyond the vicious cycle: The role of innate osteoimmunity, automimicry and tumor-inherent changes in dictating bone metastasis

Bone metastasis is a fatal consequence of a subset of solid malignancies that fail to respond to conventional therapies. While a myriad of factors contribute to osteotropism and disseminated cell survival and outgrowth in bone, efforts to inhibit tumor cell growth in the bone-metastatic niche have largely relied on measures that disrupt the bi-directional interactions between bone resident and tumor cells. However, the targeting of isolated stromal interactions has proven ineffective to date in inhibiting bone-metastatic progression and patient mortality. Osteoimmune regulation is now emerging as a critical determinant of metastatic growth in the bone microenvironment. While this has highlighted the importance of innate immune populations in dictating the temporal development of overt bone metastases, the osteoimmunological processes that underpin tumor cell progression in bone remain severely underexplored. Along with tumor-intrinsic alterations that occur specifically within the bone microenvironment, innate osteoimmunological crosstalk poses an exciting area of future discovery and therapeutic development. Here we review current knowledge of the unique exchange that occurs between bone resident cells, innate immune populations and tumor cells that leads to the establishment of a tumor-permissive milieu.

Metastases of malignant neoplasms: Historical, biological, & clinical considerations

The metastasis of neoplastic cells from their site of origin to distant anatomic locations continues to be the principal cause of death from malignant tumors, and that fact has been recognized by physicians for over a century. After the work done by Halsted in the treatment of breast cancer in the 1880s, accepted surgical canon held that metastasis occurred in a linear fashion, with centrifugal "growth in continuity" from the primary neoplasm that first involved regional lymph nodes. Those structures were considered to then be the sources of more distant, visceral metastases. With that premise in mind, radical and "ultra-radical" surgical procedures were devised to remove as many lymph nodes as possible in the treatment of carcinomas and melanomas. However, such interventions were ineffective in altering tumor-related mortality. This review considers the details of the historical material just mentioned. It also reviews currently-held concepts on biological mechanisms of metastasis, the "sentinel" lymph node biopsy technique, and the important topic of metastatic tumor "dormancy" as the cause of surgical treatment failure. Finally, predictive models of tumor behavior are discussed, which are based on gene signatures. These will likely be the key to identifying malignant lesions of low surgical stage that ultimately prove fatal through later manifestation of metastasis.

Surviving at a distant site: The organotropism of metastatic breast cancer

Many cancers demonstrate a non-random distribution of sites for distant relapse while others have the propensity to metastasize to multiple organ systems. One of the notable recent findings is that the breast cancer subtypes differ not only in their biological characteristics as primary tumors but also in their capacity for metastatic progression. This information could potentially be utilized in treatment decision making and surveillance strategies.

A no-touch technique for pulmonary wedge resection of lung cancer

OBJECTIVE

Many of the surgical patients with lung cancer die by metastasis originated from circulating tumor cells (CTCs) which are seeds of metastases. A ring-shaped catching forceps, which generates the great pressure by compression, may reduce the risk of tumor cell spreading. Here, we investigated the efficacy of such forceps based on CTC occurrence.

METHODS

Twenty-three patients with clinical stage IA lung cancer who underwent a pulmonary wedge resection were investigated in a clinical-pathological manner. They were divided into those treated using ring forceps catching without tumor release (R group) (n = 16) and non-complete use of ring forceps (N group) (n = 7), then were determined circulating tumor cells (CTCs).

RESULTS

Radiographic findings, tumor location, pathological diagnosis, and stapling method were not significantly different between the groups. The risk of detection of CTCs after surgery was significantly lower in group R (12.5 vs. 85.7%, p = 0.02), whereas there were no significant differences found in risk of negative-stapled margin cytology, pre-OP CTC detection, V (+), Ly (+), and Pl (+).

CONCLUSIONS

Patients who underwent pulmonary wedge resection of lung cancer had low chance of CTC detection after surgery when they were treated with ring forceps without tumor release, which might become a no-touch isolation technique.

Advances in targeting the transforming growth factor β1 signaling pathway in lung cancer radiotherapy

Lung cancer was demonstrated to be the most lethal type of malignant tumor amongst humans in the global cancer statistics of 2012. As one of the primary treatments, radiotherapy has been reported to induce remission in, and even cure, patients with lung cancer. However, the side effects of radiotherapy may prove lethal in certain patients. In past decades, the transforming growth factor β1 (TGFB1) signaling pathway has been revealed to serve multiple functions in the control of lung cancer progression and the radiotherapy response. In mammals, this signaling pathway is initiated through activation of the TGFB1 receptor complex, which signals via cytoplasmic SMAD proteins or other downstream signaling pathways. Multiple studies have demonstrated that TGFB1 serves important functions in lung cancer radiotherapy. The present study summarized and reviewed recent progress in elucidating the function of the TGFB1 signaling pathway in predicting radiation pneumonitis, as well as current strategies for targeting the TGFB1 signaling pathway in lung cancer radiotherapy, which may provide potential targets for lung cancer therapy.

BRCA1-Associated Protein Increases Invasiveness of Esophageal Squamous Cell Carcinoma

BACKGROUND & AIMS

We performed a screen for genes whose expression correlates with invasiveness of esophageal squamous cell carcinoma (ESCC) cells. We studied the effects of overexpression and knockdown of these genes in cell lines and expression levels in patient samples.

METHODS

We selected genes for analysis from 11 loci associated with risk of ESCC. We analyzed the effects of knocking down expression of 47 of these genes using RNA interference on-chip analysis in ESCC cells and HeLa cells. Cells with gene overexpression and knockdown were analyzed in migration and invasion assays or injected into nude mice and metastasis of xenograft tumors was quantified. We collected ESCC and non-tumor esophageal tissues from 94 individuals who underwent surgery in China from 2010 and 2014; clinical information was collected and survival time was measured from the date of diagnosis to the date of last follow-up or death. Levels of messenger RNAs (mRNAs) were quantified by RNA sequencing, and levels of proteins were determined from immunoblot analyses. Patient survival was compared with mRNA levels using Kaplan-Meier methods and hazard ratios were calculated by Cox models.

RESULTS

We identified 8 genes whose disruption increased migration and 10 genes whose disruption reduced migration. Knockdown of BRCA1-associated protein gene (BRAP) significantly reduced migration of KYSE30, KYSE150, and HeLa cells. In patient tumors, 90% of ESCCs examined had higher levels of BRAP protein than paired non-tumor tissues, and 63.8% had gains in BRAP DNA copy number. Levels of BRAP mRNA in ESCC tissues correlated with patient survival time, and high expression increased risk of death 2.4-fold compared with low expression. ESCCs that had metastasized to lymph node had significantly higher levels of BRAP mRNA than tumors without metastases. Knockdown of BRAP in ESCC and HeLa cell lines significantly reduced migration and invasiveness; these cell lines formed less metastases in mice than control cells. Nuclear translocation of the nuclear factor-κB (NF-κB) P65 subunit and phosphorylation of inhibitor of NF-κB kinase subunit β (IKBKB or IKKβ) increased in cells that overexpressed BRAP and decreased in cells with BRAP knockdown. In immunoprecipitation assays, BRAP interacted directly with IKKβ. Expression of matrix metalloproteinase 9 and vascular epithelial growth factor C, which are regulated by NF-κB, was significantly reduced in cells with knockdown of BRAP and significantly increased in cells that overexpressed BRAP.

CONCLUSIONS

Expression of BRAP is increased in ESCC samples compared with non-tumor esophageal tissues; increased expression correlates with reduced patient survival time and promotes metastasis of xenograft tumors in mice. BRAP overexpression leads to increased activity of NF-κB and expression of matrix metalloproteinase 9 and vascular epithelial growth factor C.

Differential role of Interleukin-1 and Interleukin-6 in K-Ras-driven pancreatic carcinoma undergoing mesenchymal transition

K-Ras mutations are a hallmark of human pancreatic adenocarcinoma (PDAC) and epithelial-mesenchymal-transition (EMT) is a driver of progression. Oncogenic K-Ras causes the constitutive activation of NF-kB and the switch-on of an inflammatory program, which further fuels NF-kB and STAT3 activation. In this study we investigated how inflammatory pathways triggered by oncogenic K-Ras are regulated in human pancreatic cancer cells with distict epithelial or mesenchymal phenotype. Our results demonstrate that in cells with epithelial features, K-Ras driven inflammation is under the control of IL-1, while in cells undergoing EMT, is IL-1 independent. In pancreatic tumor cells with EMT phenotype, treatment with IL-1R antagonist (Anakinra) did not inhibit inflammatory cytokine production and tumor growth in mice. In these cells IL-6 is actively transcribed by the EMT transcription factor TWIST. Targeting of mesenchymal pancreatic tumors in vivo with anti-IL-6RmAb (RoActemra) successfully decreased tumor growth in immunodeficient mice, inhibited the inflammatory stroma and NF-kB-p65 and STAT3 phosphorylation in cancer cells. The results confirm that IL-1 is an important driver of inflammation in epithelial pancreatic tumors; however, tumor cells undergoing EMT will likely escape IL-1R inhibition, as IL-6 is continuously transcribed by TWIST. These findings have implications for the rational targeting of inflammatory pathways in human pancreatic cancer.

Recent opportunities in matrix metalloproteinase inhibitor drug design for cancer

INTRODUCTION

The overexpression of matrix metalloproteinase (MMP) plays an important role in the context of tumor invasion and metastasis, and MMP-2 has been characterized as the most validated target for cancer. Therefore, it is necessary to design matrix metalloproteinase inhibitors (MMPIs) that would be active and selective against MMP-2 but non-selective toward other MMPs. Areas covered: This article clearly describes the structural character of MMP-2 followed by a review of the recent development of selective MMP-2 inhibitors based on their basic structures. Expert opinion: Over the past 30 years, MMPs have been considered to be attractive cancer targets, and several different types of synthetic inhibitors have been identified as anticancer agents, but only a small number of small MMPIs have been examined in clinical trials, and none of these molecules has been established as anticancer drugs due to their adverse effects. One major possibility is that the MMPIs used in clinical trials were broad-spectrum drugs that also inhibited the anti-tumor effects and influenced the mediation of the normal physiological processes of MMPs. MMP-2 has recently been characterized as the most validated target for cancer. Therefore, the design and synthesis of selective MMP-2 inhibitors would be helpful for the treatment of cancer.

Cell lineage determinants as regulators of breast cancer metastasis

The mammary epithelium is organized in a hierarchy of mammary stem cells (MaSCs), progenitors, and differentiated cells. The development and homeostasis of mammary gland are tightly controlled by a complex network of cell lineage regulators. These determinants of cellular hierarchy are frequently deregulated in breast tumor cells and closely associated with cancer progression and metastasis. They also contribute to the diversity of breast cancer subtypes and their distinct metastatic patterns. Cell fate regulators that normally promote stem/progenitor activities can serve as drivers for epithelial-mesenchymal transition and metastasis whereas regulators that promote terminal differentiation generally suppress metastasis. In this review, we discuss how some of the key factors function in normal mammary lineage determination and how these processes are hijacked by tumor cells to enhance metastasis. Understanding the molecular connections between normal development and cancer metastasis will enable the development of more specific and effective therapeutic approaches targeting metastatic tumor cells.

A formulation of pancreatic pro-enzymes provides potent anti-tumour efficacy: a pilot study focused on pancreatic and ovarian cancer

Proteolytic enzymes have shown efficacy in cancer therapy. We present a combination of the two pro-enzymes Trypsinogen and Chymotrypsinogen A with potent in vitro and in vivo anti-tumour efficacy. A synergetic anti-tumour effect for Trypsinogen and Chymotrypsinogen A was determined at a ratio 1:6 (named PRP) using 24 human cancer cell lines. The antiangiogenic effect of PRP was analysed by matrigel-based tube formation and by fibrous capsule formation assays. Furthermore, cell invasion and wound healing assays together with qRT-PCR determination of epithelial-to-mesenchymal transition (EMT) markers were performed on human cancer cells treated with PRP. Additionally, in vivo pharmacokinetic studies were implemented and the PRP's anti-tumour efficacy was explored against orthotopic pancreatic and ovarian cancer tumours. PRP formulation was proven to inhibit in vitro angiogenesis, tumour growth, cancer cell migration and invasiveness; and to be an effective and well tolerated in vivo anti-tumour treatment. Finally, the clinical efficacy of a suppository formulation containing both pancreatic pro-enzymes in the context of a UK Pharmaceuticals Special Scheme was evaluated in advanced cancer patients. Consequently, PRP could have relevant oncological clinical applications for the treatment of advanced or metastatic pancreatic adenocarcinoma and advanced epithelial ovarian cancer.

Circulating Tumor Cells as Cancer Biomarkers in the Clinic

It is believed that the development of metastatic cancer requires the presence of circulating tumor cells (CTCs) , which are found in a patient's circulation as rare abnormal cells comingled with billions of the normal red and white blood cells. The systems developed for detection of CTCs have brought progress to cancer treatment. The molecular characterization of CTCs can aid in the development of new drugs, and their presence during treatment can help clinicians determine the prognosis of the patient. Studies have been carried out in patients early in the disease course, with only primary tumors, and the role of CTCs in prognosis seems to be as important as it is in patients with metastatic disease. The published studies on CTCs have focused on their prognostic significance, their utility in real-time monitoring of therapies, the identification of therapeutic and resistance targets, and understanding the process of metastasis . The analysis of CTCs during the early stages, as a "liquid biopsy," helps to monitor patients at different points in the disease course, including minimal residual disease, providing valuable information about the very early assessment of treatment effectiveness. Finally, CTCs can be used to screen patients with family histories of cancer or with diseases that can lead to the development of cancer. With standard protocols, this easily obtained and practical tool can be used to prevent the growth and spread of cancer. In this chapter, we review some important aspects of CTCs , surveying the disease aspects where these cells have been investigated.

SPSB3 targets SNAIL for degradation in GSK-3β phosphorylation-dependent manner and regulates metastasis

Epithelial-mesenchymal transition (EMT) is a process during which normal epithelial cells acquire mesenchymal characteristics. EMT has a critical role in various human diseases especially in cancer. EMT facilitates tumor initiation and progression by mediating cancer cell stemness and motility. Zinc finger transcription factor SNAIL is one of the most important initiators of EMT. Therefore, it is of great significance to understand the regulating mechanism of SNAIL. In this study, we carried out a luciferase-based genome-wide screening using small interfering RNA library against ~200 of E3 ligases and ubiquitin-related genes and identified SOCS box protein SPSB3 as a novel E3 ligase component that targets SNAIL into polyubiquitination and degradation in response to GSK-3β phosphorylation of SNAIL. Functionally, we observed that SPSB3 overexpression greatly inhibits tumor metastasis by regulating SNAIL degradation both in vitro and in vivo. The expression of SPSB3 and SNAIL are negatively correlated in human esophageal squamous cell carcinoma tissues, and low SPSB3 expression indicates lymph node metastasis. Moreover, high SPSB3 expression indicates good survivals in various kinds of cancer. Collectively, these findings suggest that SPSB3-mediated SNAIL degradation has a vital role in regulating EMT and cancer progression.

Overexpression of NEDD9 in renal cell carcinoma is associated with tumor migration and invasion

Scaffold protein neural precursor cell expressed, developmentally downregulated 9 (NEDD9) is a member of the Crk-associated substrate protein family and is known to be a biomarker in multiple cancer types. It serves a critical function in regulating cell proliferation, migration, invasion and survival. The objective of this study was to evaluate the potential effects of NEDD9 in renal cell carcinoma (RCC). The expression of NEDD9 was analyzed by immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction. NEDD9 protein and mRNA levels were significantly upregulated in RCC tissues compared with normal tissues (P<0.001). Furthermore, the NEDD9 immunostaining level was significantly associated with primary tumor stage and tumor, node, metastasis stage (P<0.05). High NEDD9 expression resulted in significantly lower survival rates for patients compared with normal NEDD9 expression (P<0.01). In addition, wound healing and transwell assays indicated that NEDD9 depletion by small interfering RNA significantly attenuated the migration and invasion of RCC cells (P<0.001). The present data suggested that NEDD9 may be a novel target for prevention and treatment of RCC metastasis and recurrence.

MicroRNA-30a suppresses autophagy-mediated anoikis resistance and metastasis in hepatocellular carcinoma

MiRNA-30a (miR-30a) was previously reported as one of metastatic hepatocellular carcinoma (HCC)-related microRNAs. However, the function of miR-30a on enhancing our biological understanding of HCC metastasis is not clear. This study demonstrated that miR-30a was significantly down-regulated in HCC tissues and cell lines, and was associated with vascular invasion, metastasis potential and recurrent disease in HCC. Functional studies confirmed that miR-30a could inhibit the metastasis of HCC in a well-established nude mouse model of lung metastasis. Moreover, miR-30a was proved to prevent anoikis inhibition of HCC cells in vivo and in vitro. Mechanically, autophagy related protein Beclin 1 and Atg5 were direct downstream targets of miR-30a, and mediated autophagy activity influence of miR-30a in HCC. Taken together, downregulated miR-30a in metastatic HCC mediates Beclin 1 and Atg5-dependent autophagy, which confers anoikis resistance in HCC cells. The molecular basis of autophagy action during this process partly contributes to the HCC metastasis, suggesting that targeting autophagy via miR-30a may have therapeutic implications for the prevention of HCC recurrence/metastasis.

MET Activation and Physical Dynamics of the Metastatic Process: The Paradigm of Cancers of Unknown Primary Origin

The molecular and cellular mechanisms which drive metastatic spread are the topic of constant debate and scientific research due to the potential implications for cancer patients' prognosis. In addition to genetics and environmental factors, mechanics of single cells and physical interaction with the surrounding environment play relevant role in defining invasive phenotype. Reconstructing the physical properties of metastatic clones may help to clarify still open issues in disease progression as well as to lead to new diagnostic and therapeutic approaches. In this perspective cancer of unknown primary origin (CUP) identify the ideal model to study physical interactions and forces involved in the metastatic process. We have previously demonstrated that MET oncogene is mutated with unexpected high frequency in CUPs. We here analyze and discuss how the MET activation by somatic mutation may affect physical properties in giving rise to such a highly malignant syndrome, as that defined by CUP.

Grape seed proanthocyanidins inhibit the proliferation, migration and invasion of tongue squamous cell carcinoma cells through suppressing the protein kinase B/nuclear factor-κB signaling pathway

Tongue squamous cell carcinoma (TSCC) is the most common oral squamous cell carcinoma. Despite significant advances in combined therapies, the 5-year survival rate of patients with TSCC has not notably improved; this is due to regional recurrences and lymph node metastasis. Grape seed proanthocyanidins (GSPs) are consumed as dietary supplements worldwide and possess anticancer activity against several different types of cancer. However, their effect on TSCC and the underlying mechanisms by which they function remain unclear. In the present study, it was identified that GSPs significantly inhibited the viability and induced the apoptosis of Tca8113 cells in a dose-dependent manner. This was associated with a significantly increased expression of the pro-apoptosis regulator BAX protein and a significantly decreased expression of the anti-apoptosis regulator Bcl-2 protein at 100 µg/ml GSPs. In addition, at non-toxic concentrations GSPs significantly inhibited the secretion of matrix metalloproteinase-2 (MMP-2) and MMP-9 from Tca8113 cells, as well as their migration and invasion. Furthermore, it was demonstrated that GSPs significantly inhibited the phosphorylation of protein kinase B (Akt) and IκB kinase, as well as the translocation of nuclear factor-κB (NF-κB) into the nucleus of Tca8113 cells. Taken together, these results suggest that GSPs inhibit the proliferation, migration and invasion of Tca8113 cells through suppression of the Akt/NF-κB signaling pathway. This indicates that GSPs may be developed as a novel potential chemopreventive agent against TSCC.

pH-Sensitive Nano-Complexes Overcome Drug Resistance and Inhibit Metastasis of Breast Cancer by Silencing Akt Expression

The therapy of breast cancer is encumbered by drug resistance and metastasis, which can be due to a defective PI3K/AKT/mTOR signaling pathway. This study was aimed at improving the anti-cancer effect of the chemotherapeutic agent paclitaxel (PTX) on the drug resistant and metastatic breast cancer by co-delivering PTX and a siRNA, siAkt, directed at silencing the Akt expression.

Methods: The pH-sensitive amphiphilic polymer, poly [(1,4-butanediol)-diacrylate-β-N, N-diisopropylethylenediamine]-polyethyleneimine (BDP) was synthesized. The PTX-loaded BDP micelle/siAkt nano-complex (PMA) was prepared and characterized. The cellular uptake, cytotoxicity, RNA interference efficiency, biodistribution, pharmacokinetics, pharmacodynamics, and biocompatibility of PMA in the murine metastatic breast cancer 4T1 cells and the 4T1 tumor-bearing mice were evaluated.

Results: PMA was stable at the neutral as well as tumor extracellular pH and released the drugs in the intra-endo/lysosome acidic environment. In 4T1 cells, the RNA interference against the Akt gene down-regulated the expression of Akt and P-glycoprotein and up-regulated the expression of Caspase-3. The down-regulated P-gp inhibits the efflux of PTX thereby increasing its intracellular concentration, improving the cytotoxicity, and inhibiting the migration and invasion of 4T1 cells. In the 4T1 tumor-bearing mice, co-delivery of PTX and siAkt by PMA achieved a tumor inhibiting rate of 94.1% and suppressed 96.8% lung metastases. PMA did not cause pathological lesions in normal organs.

Conclusion: PMA, by virtue of overcoming drug resistance and simultaneously restraining lung metastasis, might be an efficient drug delivery system for the therapy of breast cancer.

Inflammatory Monocytes Loading Protease-Sensitive Nanoparticles Enable Lung Metastasis Targeting and Intelligent Drug Release for Anti-Metastasis Therapy

Metastasis causes high mortality of breast cancer, and the inability of drug delivery to metastatic sites remains a crucial challenge for antimetastasis therapy. Herein, we report that inflammatory monocytes loading legumain-activated nanoparticles can actively target lung metastases and initiate metastasis-specific intelligent drug release for antimetastasis therapy. The cytotoxic mertansine is conjugated to poly(styrene-co-maleic anhydride) with a legumain-sensitive peptide and self-assembled into nanoparticles (SMNs), and then loaded into inflammatory monocytes to prepare the SMNs-loaded monocytes delivery system (M-SMNs). M-SMNs would be in living state in circulation to ensure their active targeting to lung metastases, and responsively damaged at the metastatic sites upon the differentiation of monocytes into macrophages. The anticancer drugs are intelligently released from M-SMNs as free drug molecules and drug-loaded microvesicles, resulting in considerable inhibition on the proliferation, migration, and invasion activities of metastatic 4T1 breast cancer cells. Moreover, M-SMNs significantly improve the delivery to lung metastases and penetrate the metastatic tumors, thus producing a 77.8% inhibition of lung metastases. Taken together, our findings provide an intelligent biomimetic drug delivery strategy via the biological properties of inflammatory monocytes for effective antimetastasis therapy.

Molecular characterization of circulating tumor cells-from bench to bedside

Circulating tumor cells (CTCs) are cancer cells discovered in cancer patients' peripheral blood that successfully escape from the primary tumor site and/or metastases, struggle to survive in the bloodstream, and have potential for seeding metastases. Numerous methods have been proposed to capture CTCs. The value of CTCs as a means of understanding cancer metastasis and a major form of 'liquid biopsy' has been widely demonstrated. Recently, single-cell molecular analyses of CTCs have provided profound biological insights into tumor heterogeneity, mechanism of metastasis and tumor evolution. In addition, because CTC analysis is non-invasive, CTCs exhibit great potential as biomarkers for assessment of cancer prognosis and therapy response. In this review, we summarize modern technologies for CTC detection and isolation, single-cell genomic/transcriptomic characterization of CTCs, and prospective clinical applications of CTCs. We expect that, after further technical improvements in methods of detection and sequencing, CTC analyses will shed new light on the mechanisms driving cancer metastasis and benefit many cancer patients.

Radiological classification of multiple lung cancers and the prognostic impact based on the presence of a ground glass opacity component on thin-section computed tomography

OBJECTIVES

Revised TNM classification has proposed a new clinical classification of lung cancers with multiple pulmonary sites. However, definition of the radiological findings and their prognostic impacts are still controversial. Therefore, we evaluated the prognostic impact of multiple lung cancers based on the radiologic classifications concluded from findings on thin-section computed tomography.

METHODS

Among surgically resected 1440 c-stage I lung cancer patients, 246 (17.1%) with multiple lung tumors were reviewed. All tumors were classified into 3 groups based on the extent of ground glass opacity (GGO), i.e., consolidation tumor ratio (CTR); GGO-dominant (GD; 0≤CTR<0.5), solid-dominant (SD; 0.5≤CTR<1.0) and pure-solid (PS; CTR=1.0). Multiple lung tumors were divided radiologically into 6 groups, and their prognoses were compared with that of c-stage I lung cancer using Cox's proportional hazard model.

RESULTS

Of all, 198 patients (80.5%) were surgically resected more than two tumors and determined as multiple lung cancers pathologically. The number of patients with GD+GD=73 (30%), GD+SD=54 (22%), GD+PS=53 (21%), SD+SD=12 (5%), SD+PS=20 (8%) and PS+PS=34 (14%). A multivariate analysis revealed that PS+PS group consisted of independently significant prognosticator (p<0.001). The overall survival (OS) was 97.3% in GD+GD, 98.2% in GD+SD, 84.8% in GD+PS, 90.9% in SD+SD, 78.7% in SD+PS and 41.8% in PS+PS groups, showing a significant difference between PS+PS group and the other groups. Furthermore, the OS of 1194 c-stage I lung cancer patients was 78.2%, and the prognosis of PS+PS group was significantly poor compared with that of c-stage I (p<0.001), while OS of the other groups were almost equivalent or much better than the c-stage I.

CONCLUSIONS

Among multiple lung cancers, PS+PS group is associated with poor survival, which would contribute to the upstaging of T descriptors. The presence of GGO is extremely important when considering the correlation between radiological classification of multiple lung cancers and its prognosis.

A Comparative Study of Clinical Intervention and Interventional Photothermal Therapy for Pancreatic Cancer

Although nanoparticle-based photothermal therapy (PTT) has been intensively investigated recently, its comparative efficiency with any clinical cancer treatments has been rarely explored. Herein for the first time we report a systematic comparative study of clinical iodine-125 (¹²⁵ I) interstitial brachytherapy (IBT-125-I) and interventional PTT (IPTT) in an orthotopic xenograft model of human pancreatic cancer. IPTT, based on the nanoparticles composing of anti-urokinase plasminogen activator receptor (uPAR) antibody, polyethylene glycol (PEG), and indocyanine green (ICG) modified gold nanoshells (hereinafter uIGNs), is directly applied to local pancreatic tumor deep in the abdomen. In comparison to IBT-125-I, a 25% higher median survival rate of IPTT with complete ablation by one-time intervention has been achieved. The IPTT could also inhibit pancreatic tumor metastasis which can be harnessed for effective cancer immunotherapy. All results show that this IPTT is a safe and radical treatment for eradicating tumor cells, and may benefit future clinical pancreatic cancer patients.

A regulated PNUTS mRNA to lncRNA splice switch mediates EMT and tumour progression

The contribution of lncRNAs to tumour progression and the regulatory mechanisms driving their expression are areas of intense investigation. Here, we characterize the binding of heterogeneous nuclear ribonucleoprotein E1 (hnRNP E1) to a nucleic acid structural element located in exon 12 of PNUTS (also known as PPP1R10) pre-RNA that regulates its alternative splicing. HnRNP E1 release from this structural element, following its silencing, nucleocytoplasmic translocation or in response to TGFβ, allows alternative splicing and generates a non-coding isoform of PNUTS. Functionally the lncRNA-PNUTS serves as a competitive sponge for miR-205 during epithelial-mesenchymal transition (EMT). In mesenchymal breast tumour cells and in breast tumour samples, the expression of lncRNA-PNUTS is elevated and correlates with levels of ZEB mRNAs. Thus, PNUTS is a bifunctional RNA encoding both PNUTS mRNA and lncRNA-PNUTS, each eliciting distinct biological functions. While PNUTS mRNA is ubiquitously expressed, lncRNA-PNUTS appears to be tightly regulated dependent on the status of hnRNP E1 and tumour context.

Analytical evaluation for somatic mutation detection in circulating tumor cells isolated using a lateral magnetophoretic microseparator

CTCs are currently in the spotlight because provide comprehensive genetic information that enables monitoring of the evolution of cancer and selection of appropriate therapeutic strategies that cannot be obtained from a single-site tumor biopsy. Despite their importance, current techniques for isolating CTCs are limited in terms of their ability to yield high-quality CTCs from peripheral blood for use in profiling cancer genetic mutations by DNA sequencing technologies. This paper introduces a lateral magnetophoretic microseparator (the 'CTC-μChip') for isolating highly pure CTCs from blood, which facilitates the detection of somatic mutations in isolated CTCs. To isolate CTCs from peripheral blood, nucleated cells were first prepared by red blood cell lysis. Then, CTCs were isolated from nucleated cells within 30 min using the CTC-μChip. Analytical evaluation using 5 mL blood samples spiked with 5-50 MCF7 breast cancer cells demonstrated that the average recovery rate of the CTC-μChip was 99.08 %. The average number of residual white blood cells (WBCs) in isolated samples was 53, meaning that the WBC depletion rate is 472,000-fold (5.67 log), assuming that blood contains 5 × 10(6) WBCs per milliliter. The isolated MCF7 cells had a purity of 6.9 - 67.9 %, depending on the spiked MCF7 concentration. Using next-generation sequencing technology, heterozygous somatic mutations (PIK3CA and APC) of MCF7 cells were evaluated in the isolated samples. The results showed that somatic mutations could be detected in as few as two MCF7 cells per milliliter of blood, indicating that the CTC-μChip facilitates the detection of somatic variants in CTCs.

Cancer metastasis - tricks of the trade

Decades of cancer research have unraveled genetic, epigenetic and molecular pathways leading to plausible therapeutic targets; many of which hold great promise in improving clinical outcomes. Metastatic tumors become evident early on and are one of the major causes of cancer-related fatalities worldwide. This review depicts the sequential events of cancer metastasis. Genetic and epigenetic heterogeneity influences local tumor cell invasion, intravasation, survival in circulation, extravasation and colonization to distant sites. Each sequential event is associated with heterogeneous tumor microenvironment, gain of competence, unique population of cancer stem cells (CSCs), circulatory pathway, compatible niche and immune system support. A tight regulation of metastasis-promoting mechanisms and, in parallel, evading inhibitory mechanisms contribute to the severity and site of metastasis. A comprehensive understanding of tumor cell fate as an individual entity, as well as in combination with different promoting factors and associated molecular mechanisms, is anticipated in the coming years. This will enable scientists to depict design strategies for targeted cancer therapies.

Antrodia camphorata inhibits metastasis and epithelial-to-mesenchymal transition via the modulation of claudin-1 and Wnt/β-catenin signaling pathways in human colon cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Antrodia camphorata (AC) is a well known traditional Chinese medicinal mushroom in Taiwan, has been used to treat various diseases including cancer.

MATERIALS AND METHODS

In this study, we investigated the anti-metastatic and anti-EMT properties of a fermented culture broth of AC in human colon SW480^claudin-1- and metastatic SW620^claudin-1+ cancer cells in vitro.

RESULTS

AC down-regulates claudin-1 and inhibits the proliferation and colony-formation abilities of both SW620^claudin-1+ and SW480^claudin-1- cells. In highly metastatic SW620^claudin-1+ cells, non-cytotoxic concentrations of AC significantly inhibited migration/invasion, accompanied by the down-regulation of MMP-2 and MMP-9 proteins. AC decreased nuclear translocation of Wnt/β-catenin through a GSK3β-dependent pathway. AC consistently inhibited EMT by up-regulating the epithelial and downregulating the mesenchymal marker proteins. In SW480^claudin-1- cells, AC suppressed migration/invasion potentially through the inhibition of the PI3K/AKT/NFκB signaling pathways without altering the expression levels of β-catenin and GSK3β proteins.

CONCLUSION

Altogether, this study demonstrates the anti-metastatic and anti-EMT activities of AC, which may contribute to the development of a chemopreventive agent for colon cancer.

Current concepts in bone metastasis, contemporary therapeutic strategies and ongoing clinical trials

Background

Elucidation of mechanisms regulating bone metastasis has progressed significantly in recent years and this has translated to many new therapeutic options for patients with bone metastatic cancers. However, the rapid rate of progress in both the basic science literature and therapies undergoing clinical trials makes staying abreast with current developments challenging. This review seeks to provide an update on the current state of the science in bone metastasis research and give a snap shot of therapies in clinical trials for bone metastatic cancer.

Main body

Bone metastasis represents a difficult to treat clinical scenario due to pain, increased fracture risk, decreased quality of life and diminished overall survival outcomes. Multiple types of cancer have the specific ability to home to the bone microenvironment and cause metastatic lesions. This osteotropism was first described by Stephen Paget nearly 100 years ago as the ‘seed and soil’ hypothesis. Once cancer cells arrive at the bone they encounter a variety of cells native to the bone microenvironment which contribute to the establishment of bone metastatic lesions. In the first part of this review, the ‘seed and soil’ hypothesis is revisited while emphasizing recent developments in understanding the impact of native bone microenvironment cells on the metastatic process. Next, approved therapies for treating bone metastasis at the systemic level as well as those that target the bone microenvironment are discussed and current National Comprehensive Cancer Network (NCCN) guidelines relating to treatment of bone metastases are summarized. Finally, all open interventional clinical trials for therapies relating to treatment of bone metastasis have been complied and categorized.

Conclusion

Understanding the recent advancements in bone metastasis research is important for continued development of novel bone targeted therapies. The plethora of ongoing clinical trials will hopefully translate into improved treatments options for patients suffering from bone metastatic cancers.

Deoxyarbutin displays antitumour activity against melanoma in vitro and in vivo through a p38-mediated mitochondria associated apoptotic pathway

Deoxyarbutin (DeoxyArbutin, dA), a natural compound widely used in skin lighting, displayed selectively cytotoxicity in vitro. In the study, we found that dA significantly inhibited viability/proliferation of B16F10 melanoma cells, induced tumour cell arrest and apoptosis. Furthermore, dA triggered its pro-apoptosis through damaging the mitochondrial function (membrane potential loss, ATP depletion and ROS overload generation etc.) and activating caspase-9, PARP, caspase-3 and the phosphorylation of p38. Treatment with p38 agonist confirmed the involvement of p38 pathway triggered by dA in B16F10 cells. The in vivo finding also revealed that administration of dA significantly decreased the tumour volume and tumour metastasis in B16F10 xenograft model by inhibiting tumour proliferation and inducing tumour apoptosis. Importantly, the results indicated that dA was specific against tumour cell lines and had no observed systemic toxicity in vivo. Taken together, our study demonstrated that dA could combate tumour in vitro and in vivo by inhibiting the proliferation and metastasis of tumour via a p38-mediated mitochondria associated apoptotic pathway.

Tumour heterogeneity promotes collective invasion and cancer metastatic dissemination

Heterogeneity within tumour cell populations is commonly observed in most cancers. However, its impact on metastatic dissemination, one of the primary determinants of the disease prognosis, remains poorly understood. Working with a simplified numerical model of tumour spheroids, we investigated the impact of mechanical heterogeneity on the onset of tumour invasion into surrounding tissues. Our work establishes a positive link between tumour heterogeneity and metastatic dissemination, and recapitulates a number of invasion patterns identified in vivo, such as multicellular finger-like protrusions. Two complementary mechanisms are at play in heterogeneous tumours. A small proportion of stronger cells are able to initiate and lead the escape of cells, while collective effects in the bulk of the tumour provide the coordination required to sustain the invasive process through multicellular streaming. This suggests that the multicellular dynamics observed during metastasis is a generic feature of mechanically heterogeneous cell populations and might rely on a limited and generic set of attributes.

DNMT1-maintained hypermethylation of Krüppel-like factor 5 involves in the progression of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the major subtype of renal cell carcinoma (RCC) that is resistant to conventional radiation and chemotherapy. It is a challenge to explore effective therapeutic targets and drugs for this kind of cancer. Transcription factor Krüppel-like factor 5 (KLF5) exerts diverse functions in various tumor types. By analyzing cohorts of the Cancer Genome Atlas (TCGA) data sets, we find that KLF5 expression is suppressed in ccRCC patients and higher level of KLF5 expression is associated with better prognostic outcome. Our further investigations demonstrate that KLF5 genomic loci are hypermethylated at proximal exon 4 and suppression of DNA methyltransferase 1 (DNMT1) expression by ShRNAs or a methylation inhibitor 5-Aza-CdR can recover KLF5 expression. Meanwhile, there is a negative correlation between expressions of KLF5 and DNMT1 in ccRCC tissues. Ectopic KLF5 expression inhibits ccRCC cell proliferation and migration/invasion in vitro and decreases xenograft growth and metastasis in vivo. Moreover, 5-Aza-CdR, a chemotherapy drug as DNMTs' inhibitor that can induce KLF5 expression, suppresses ccRCC cell growth, while knockdown of KLF5 abolishes 5-Aza-CdR-induced growth inhibition. Collectively, our data demonstrate that KLF5 inhibits ccRCC growth as a tumor suppressor and highlight the potential of 5-Aza-CdR to release KLF5 expression as a therapeutic modality for the treatment of ccRCC.

KIAA1522 overexpression promotes tumorigenicity and metastasis of esophageal cancer cells through potentiating the ERK activity

Esophageal squamous cell carcinoma (ESCC) is a highly malignant tumor associated with a poor prognosis, and the molecular mechanisms underlying its formation and progression remain poorly understood. KIAA1522 is upregulated in various tumor tissues, but its function is unknown. Alterations in KIAA1522 expression and its implication in ESCC are currently unclear. In this study, an immunohistochemical analysis of ESCC tissues showed that KIAA1522 was highly expressed in 46% (157/342) of ESCC specimens and that its expression was inversely correlated with the degree of differentiation (P=0.03). Furthermore, small interfering RNA-mediated silencing of KIAA1522 revealed that overexpression of this protein reinforced malignant cell proliferation and anoikis resistance of ESCC cells in vitro. More importantly, KIAA1522 depletion significantly suppressed the growth of ESCC xenograft tumors and lung metastasis of ESCC cells in nude mice. At the molecular level, inhibition of KIAA1522 expression markedly reduced the phosphorylated extracellular signal-regulated kinase (ERK) levels in both suspended and adherent ESCC cells, suggesting that KIAA1522 might promote cell proliferation and survival via the ERK cascade. Taken together, these data suggest that upregulation of KIAA1522 might enhance tumorigenicity and metastasis of ESCC cells through potentiating the ERK activity. Thus, aberrant expression of KIAA1522 plays oncogenic roles in ESCC and might serve as a novel molecular target in ESCC treatment.

Receptor and Microenvironment Dual-Recognizable Nanogel for Targeted Chemotherapy of Highly Metastatic Malignancy

Targeted delivery of chemotherapeutic drugs to the desired lesion sites is the main objective in malignancy treatment, especially in highly metastatic malignancies. However, extensive studies around the world on traditional targeting strategies of recognizing either overexpressed receptors or microenvironments in tumors show great limitations, owing to the off-target effect and tumor homogeneity. Integration of both receptor-mediated targeting (RMT) and environment-mediated targeting (EMT) enhances the tumor accumulation and subsequent cell uptake at the same time, which may avoid these limitations. Herein, a dual targeting nanogel of PMNG engineered with both phenylboronic acid (PBA) and morpholine (MP) was reported for not only RMT via specific recognition of sialyl (SA) epitopes but also EMT toward extracellular acidity. Further engineering the nanoparticles via loading doxorubicin (DOX) brought a novel dual targeting system, that is, PMNG/DOX. PMNG/DOX demonstrated a greater targeting effect to both primary and metastatic B16F10 melanoma than the single PBA-modified nanogel (PNG) with only RMT in vitro and in vivo. Moreover, PMNG/DOX was also proved to be highly potent on inhibiting primary tumor growth as well as tumor metastasis on B16F10 melanoma-grafted mouse model. The results demonstrated the dual targeting design as a translational approach for drug delivery to highly metastatic tumor.

Detection of FAM172A expressed in circulating tumor cells is a feasible method to predict high-risk subgroups of colorectal cancer

Previous studies used to enumerate circulating tumor cells to predict prognosis and therapeutic effect of colorectal cancer. However, increasing studies have shown that only circulating tumor cells enumeration was not enough to reflect the heterogeneous condition of tumor. In this study, we classified different metastatic-potential circulating tumor cells from colorectal cancer patients and measured FAM172A expression in circulating tumor cells to improve accuracy of clinical diagnosis and treatment of colorectal cancer. Blood samples were collected from 45 primary colorectal cancer patients. Circulating tumor cells were enriched by blood filtration using isolation by size of epithelial tumor cells, and in situ hybridization with RNA method was used to identify and discriminate subgroups of circulating tumor cells. Afterwards, FAM172A expression in individual circulating tumor cells was measured. Three circulating tumor cell subgroups (epithelial/biophenotypic/mesenchymal circulating tumor cells) were identified using epithelial-mesenchymal transition markers. In our research, mesenchymal circulating tumor cells significantly increased along with tumor progression, development of distant metastasis, and vascular invasion. Furthermore, FAM172A expression rate in mesenchymal circulating tumor cells was significantly higher than that in epithelial circulating tumor cells, which suggested that FAM172A may correlate with malignant degree of tumor. This hypothesis was further verified by FAM172A expression in mesenchymal circulating tumor cells, which was strictly related to tumor aggressiveness factors. Mesenchymal circulating tumor cells and FAM172A detection may predict highrisk stage II colorectal cancer. Our research proved that circulating tumor cells were feasible surrogate samples to detect gene expression and could serve as a predictive biomarker for tumor evaluation.

MicroRNA-24-1 suppresses mouse hepatoma cell invasion and metastasis via directly targeting O-GlcNAc transferase

MicroRNAs (miRNAs) are endogenous non-coding regulatory RNAs involved in multiple cellular processes. Emerging evidences showed that miRNAs are involved in changing the cell surface glycosylation modification and oncogenesis. In this study, the role of miRNA-24-1 in O-GlcNAcylation and metastasis of mouse hepatocarcinoma cells was investigated. miRNAs expression array profiles were obtained from mouse hepatocarcinoma cell lines Hca-P and Hca-F with the low/high lymphatic metastasis potential, respectively. Based on the miRNAs expression array profiles, miRNA-24-1 expression was found to exhibit converse coincidence with metastasis potential, O-GlcNAc transferase (OGT) expression and O-GlcNAcylation. Dual-luciferase reporter assay revealed that miRNA-24-1 specifically binds to 3'-UTR of OGT. Furthermore, transfecting mouse hepatocarcinoma cells with miR-24-1 mimic and antisense oligonucleotide showed miR-24-mediates OGT expression silencing. This silencing is associated with the suppression of cell metastasis potential, down-regulation of the O-GlcNAcylation on c-Myc and decrease of c-Myc expression at the protein level rather than the mRNA level. Collectively, these results suggested that as a tumor suppressor, miR-24-1 may regulate mouse hepatocarcinoma cells migration and invasion, at least partially through targeting OGT, which could regulate the O-GlcNAcylation and the stability of this oncoprotein c-Myc. This may give insight into a novel mechanism and therapy of tumor lymphatic metastasis.

Fine-Tuning Tumor Endothelial Cells to Selectively Kill Cancer

Tumor endothelial cells regulate several aspects of tumor biology, from delivering oxygen and nutrients to shaping the immune response against a tumor and providing a barrier against tumor cell dissemination. Accordingly, targeting tumor endothelial cells represents an important modality in cancer therapy. Whereas initial anti-angiogenic treatments focused mainly on blocking the formation of new blood vessels in cancer, emerging strategies are specifically influencing certain aspects of tumor endothelial cells. For instance, efforts are generated to normalize tumor blood vessels in order to improve tumor perfusion and ameliorate the outcome of chemo-, radio-, and immunotherapy. In addition, treatment options that enhance the properties of tumor blood vessels that support a host’s anti-tumor immune response are being explored. Hence, upcoming anti-angiogenic strategies will shape some specific aspects of the tumor blood vessels that are no longer limited to abrogating angiogenesis. In this review, we enumerate approaches that target tumor endothelial cells to provide anti-cancer benefits and discuss their therapeutic potential.

Traditional Chinese medicine, Fuzheng Kang‑Ai decoction, inhibits metastasis of lung cancer cells through the STAT3/MMP9 pathway

Lung cancer is a leading cause of cancer-associated mortality worldwide, including in developing countries such as China. Traditional Chinese medicine may provide a novel insight for the treatment of patients with lung cancer. The present study aimed to uncover the mechanism by which the Chinese herbal medicine, Fuzheng Kang-Ai (FZKA), functions on lung cancer cell metastasis. The results demonstrated that treatment with FZKA markedly inhibited cell viability, migration and invasion of lung cancer cells, as determined by cell viability and Transwell assays. Notably, the activity and expression of matrix metalloproteinase 9 (MMP9) was significantly inhibited by FZKA treatment on lung cancer cells, as determined by an MMP9 activity assay and western blot analysis. Furthermore, FZKA markedly inhibited epithelial-mesenchymal transition (EMT) of lung cancer cells by inhibiting the expression of the mesenchymal markers N-cadherin and vimentin. In addition, activation of the oncoprotein signal transducer and activator of transcription 3 (STAT3) was suppressed following treatment with FZKA. Conversely, overexpression of STAT3 was able to rescue MMP9 activity following FZKA treatment. The present study indicated that FZKA may inhibit lung cancer metastasis via the STAT3/MMP9 pathway and EMT, suggesting that FZKA may serve as a novel promising therapeutic strategy for the treatment of patients with late stage lung cancer.

Circulating Tumor Cells: Moving Biological Insights into Detection

Circulating tumor cells (CTCs) have shown promising potential as liquid biopsies that facilitate early detection, prognosis, therapeutic target selection and monitoring treatment response. CTCs in most cancer patients are low in abundance and heterogeneous in morphological and phenotypic profiles, which complicate their enrichment and subsequent characterization. Several methodologies for CTC enrichment and characterization have been developed over the past few years. However, integrating recent advances in CTC biology into these methodologies and the selection of appropriate enrichment and characterization methods for specific applications are needed to improve the reliability of CTC biopsies. In this review, we summarize recent advances in the studies of CTC biology, including the mechanisms of their generation and their potential forms of existence in blood, as well as the current CTC enrichment technologies. We then critically examine the selection of methods for appropriately enriching CTCs for further investigation of their clinical applications.

PRC1 contributes to tumorigenesis of lung adenocarcinoma in association with the Wnt/β-catenin signaling pathway

Background

Protein regulator of cytokinesis-1 (PRC1) belongs to the microtubule-associated proteins (MAPs) family, and is involved in cytokinesis. Recent investigations suggest PRC1 involvement in human carcinogenesis, including breast carcinoma, hepatocellular carcinoma and etc. However, whether PRC1 contributes to lung adenocarcinoma tumorigenesis remains unknown.

Methods

Quantitative reverse-transcription polymerase chain reaction (qRT-PCR), Western blotting and Immunohistochemical staining (IHC) were used to evaluate and contrast the PRC1 expression profile in lung adenocarcinoma and adjacent normal lung tissues. We examined the clinical use of PRC1 in lung adenocarcinoma prognosis. Additionally, the tumorigenesis impact of PRC1 in lung adenocarcinoma cells was verified via in vitro and in vivo metastasis and tumorigenesis assays. Notably, Next Generation Sequencing (NGS) was performed to investigate the molecular mechanism underlying the oncogenic role of PRC1 in lung adenocarcinoma.

Results

PRC1 mRNA and protein expressions were upregulated in lung adenocarcinoma tissues compared to adjacent normal lung tissues. PRC1 protein overexpression correlated with lymph node metastasis and was an independent poor prognostic factor for lung adenocarcinoma patients. Our data implied that PRC1 depletion limited the proliferation and invasion of lung adenocarcinoma cells in vitro and lowered tumor development and lung metastasis in vivo. Remarkably, limiting PRC1 substantially prompted G2/M phase cell cycle arrest and apoptosis. Mechanistically, by conducting NGS on PRC1-depleted A549 cells and control cells, we discovered that PRC1 expression was significantly correlated with the Wnt signaling pathway.

Conclusions

This investigation offers confirmation that PRC1 is a prognostic and promising therapeutic biomarker for people with lung adenocarcinoma and takes on a key part in the activation of the Wnt/β-catenin pathway in lung adenocarcinoma development.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0682-z) contains supplementary material, which is available to authorized users.

Tumor-suppressive microRNA-452 inhibits migration and invasion of breast cancer cells by directly targeting RAB11A

Breast cancer is the most common type of malignant tumor in females, and metastasis is the most common cause of breast cancer-associated mortality. Previous studies have identified that abnormal expression of microRNAs is commonly observed in human cancer and may be crucial for cancer metastasis. In the present study, microRNA-452 (miR-452) was investigated for its ability to act as a tumor suppressor in breast cancer. miR-452 expression was quantified in breast cancer tissue samples and cell lines with reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Transwell migration and invasion assays were used to investigate the effect of miR-452 on the migration and invasion capabilities of breast cancer cells. Potential target genes of miR-452 were identified with miRanda and TargetScan. A luciferase reporter assay was performed to validate RAB11A as a putative target of miR-452, and was corroborated by RT-qPCR and western blot analyses. Finally, small interfering RNA (siRNA) was used to knockdown RAB11A expression and confirm whether miR-452 inhibited breast cancer cell migration and invasion via the negative regulation of RAB11A. The results revealed that miR-452 was downregulated in breast cancer tissues and cell lines, and that its downregulation may be associated with breast cancer metastasis, as miR-452 expression inhibited the migration and invasion capacities of breast cancer cells. RT-qPCR and western blot analyses indicated that miR-452 negatively regulated the expression of RAB11A mRNA and protein. The luciferase reporter assay revealed that miR-452 specifically bound to the 3'-untranslated region of RAB11A. Furthermore, inhibition of RAB11A with siRNA inhibited breast cancer cell migration and invasion. In conclusion, the present study has demonstrated that miR-452 may act as a tumor suppressor gene via inhibition of cell migration and invasion by targeting RAB11A in breast cancer.