Development of a metastatic fluorescent Lewis Lung carcinoma mouse model: identification of mRNAs and microRNAs involved in tumor invasion

MicroRNA-9 as a paradoxical but critical regulator of cancer metastasis: Implications in personalized medicine

Metastasis, is a development of secondary tumor growths at a distance from the primary site, and closely related to poor prognosis and mortality. However, there is still no effective treatment for metastatic cancer. Therefore, there is an urgent need to find an effective therapy for cancer metastasis. Plenty of evidence indicates that miR-9 can function as a promoter or suppressor in cancer metastasis and coordinate multistep of metastatic process. In this review, we summarize the different roles of miR-9 with the corresponding molecular mechanisms in metastasis of twelve common cancers and the multiple mechanisms underlying miR-9-mediated regulation of metastasis, benefiting the further research of miR-9 and metastasis, and hoping to bridge it with clinical applications.

Heterogeneity of circulating tumor cell dissemination and lung metastases in a subcutaneous Lewis lung carcinoma model

Subcutaneous (s.c.) tumor models are widely used in pre-clinical cancer metastasis research. Despite this, the dynamics and natural progression of circulating tumor cells (CTCs) and CTC clusters (CTCCs) in peripheral blood are poorly understood in these models. In this work, we used a new technique called 'diffuse in vivo flow cytometry' (DiFC) to study CTC and CTCC dissemination in an s.c. Lewis lung carcinoma (LLC) model in mice. Tumors were grown in the rear flank and we performed DiFC up to 31 days after inoculation. At the study endpoint, lungs were excised and bioluminescence imaging (BLI) was performed to determine the extent of lung metastases. We also used fluorescence macro-cryotome imaging to visualize infiltration and growth of the primary tumor. DiFC revealed significant heterogeneity in CTC and CTCC numbers amongst all mice studied, despite using clonally identical LLC cells and tumor placement. Maximum DiFC count rates corresponded to 0.1 to 14 CTCs per mL of peripheral blood. In general, CTC numbers did not necessarily increase monotonically over time and were poorly correlated with tumor volume. However, there was a good correlation between CTC and CTCC numbers in peripheral blood and lung metastases. We attribute the differences in CTC numbers primarily due to growth patterns of the primary tumor. This study is one of the few reports of CTC shedding dynamics in sub-cutaneous metastasis models and underscores the value of in vivo methods for continuous, non-invasive CTC monitoring.

Long noncoding RNA FBXL19-AS1 induces tumor growth and metastasis by sponging miR-203a-3p in lung adenocarcinoma

The pivotal roles of long noncoding RNAs have been reported in various cancers. Recently, FBXL19-AS1 was proposed to be involved in tumor progression. However, its role in lung adenocarcinoma (LUAD) remains elusive. In this study, we observed that FBXL19-AS1 was significantly upregulated in LUAD tissues and high FBXL19-AS1 expression in LUAD was associated with a poor prognosis. Nevertheless, miR-203-3p showed the opposite effect. Moreover, cell viability and apoptosis analysis revealed that FBXL19-AS1 knockdown could arrest LUAD cells in G0/G1 phase and inhibit cell proliferation, migration and invasion in vitro and inhibited LUAD tumor progress in vivo. Mechanistically, we identified FBXL19-AS1 could act as a miR-203a-3p sponge using dual-luciferase reporter assay. In addition, we demonstrated that downregulation of miR-203a-3p reversed growth inhibition of LUAD cells caused by FBXL19-AS1 knockdown. Finally, FBXL19-AS1/miR-203a-3p axis was found to associate with baculoviral IAP repeat-containing protein 5.1-A-like (survivin), distal-less homeobox 5, E2F transcription factor 1, and zinc finger E-box binding homeobox 2 to regulate metastasis in LUAD cells. This study reveals a significance and mechanism of FBXL19-AS1 in LUAD proliferation and metastasis and offers a potential prognostic marker and a therapeutic target for patients with LUAD.

The Atypical Chemokine Receptor Ackr2 Constrains NK Cell Migratory Activity and Promotes Metastasis

Chemokines have been shown to be essential players in a range of cancer contexts. In this study, we demonstrate that mice deficient in the atypical chemokine receptor Ackr2 display impaired development of metastasis in vivo in both cell line and spontaneous models. Further analysis reveals that this relates to increased expression of the chemokine receptor CCR2, specifically by KLRG1⁺ NK cells from the Ackr2^−/− mice. This leads to increased recruitment of KLRG1⁺ NK cells to CCL2-expressing tumors and enhanced tumor killing. Together, these data indicate that Ackr2 limits the expression of CCR2 on NK cells and restricts their tumoricidal activity. Our data have important implications for our understanding of the roles for chemokines in the metastatic process and highlight Ackr2 and CCR2 as potentially manipulable therapeutic targets in metastasis.

Anti-cancer binary system activated by bacteriophage HK022 integrase

The binary system presented in this work is based on the bacteriophage HK022 integrase recombinase that activates the expression of a silenced Diphtheria toxin gene, both controlled by the cancer specific hTERT promoter. Using a lung cancer mice model, assays of different apoptotic and anti-apoptotic factors have demonstrated that the Integrase based binary system is highly specific towards cancer cells and more efficient compared to the conventional mono system whose toxin is directly expressed under hTERT. In a mice survival test, this binary system demonstrated longer persistence compared to the untreated and the mono treated ones. The reason underlying the advantage of this binary system over the mono system seems to be an overexpression of various hTERT suppressing factors induced by the mono system.

Cancer-specific binary expression system activated in mice by bacteriophage HK022 Integrase

Binary systems based on site-specific recombination have been used for tumor specific transcription targeting of suicide genes in animal models. In these binary systems a site specific recombinase or integrase that is expressed from a tumor specific promoter drives tumor specific expression of a cytotoxic gene. In the present study we developed a new cancer specific binary expression system activated by the Integrase (Int) of the lambdoid phage HK022. We demonstrate the validity of this system by the specific expression of a luciferase (luc) reporter in human embryonic kidney 293T (HEK293T) cells and in a lung cancer mouse model. Due to the absence viral vectors and of cytotoxicity the Int based binary system offers advantages over previously described counterparts and may therefore be developed into a safer cancer cell killing system.

Far-red fluorescent cell line for preclinical study of HER2-targeted agents

We have created novel HER2-overexpressing human ovarian adenocarcinoma cell line stably transfected with far-red fluorescent protein TurboFP635. Growth characteristics, adhesion capacity and morphology of the cells do not differ from that of parental cell line. The obtained cell line (SKOV-kat) was confirmed to have high level of expression of the tumor marker HER2 comparable to that of initial cell line SKOV-3. The SKOV-kat cell line is designed for further establishment of experimental fluorescent models of HER2-overexpressing human ovarian cancer that make it possible to optimize and reduce the cost of preclinical study of agents for treatment of this disease.

A novel far-red fluorescent xenograft model of ovarian carcinoma for preclinical evaluation of HER2-targeted immunotoxins

We have created a novel fluorescent model of a human ovarian carcinoma xenograft overexpressing receptor HER2, a promising molecular target of solid tumors. The model is based on a newly generated SKOV-kat cell line stably expressing far-red fluorescent protein Katushka. Katushka is most suitable for the in vivo imaging due to an optimal combination of high brightness and emission in the "window of tissue transparency". The relevance of the fluorescent model for the in vivo monitoring of tumor growth and response to treatment was demonstrated using a newly created HER2-targeted recombinant immunotoxin based on the 4D5scFv antibody and a fragment of the Pseudomonas exotoxin A.

Prophylactic administration of fucoidan represses cancer metastasis by inhibiting vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs) in Lewis tumor-bearing mice

Fucoidan, a heparin-like sulfated polysaccharide, is rich in brown algae. It has a wide assortment of protective activities against cancer, for example, induction of hepatocellular carcinoma senescence, induction of human breast and colon carcinoma apoptosis, and impediment of lung cancer cells migration and invasion. However, the anti-metastatic mechanism that fucoidan exploits remains elusive. In this report, we explored the effects of fucoidan on cachectic symptoms, tumor development, lung carcinoma cell spreading and proliferation, as well as expression of metastasis-associated proteins in the Lewis lung carcinoma (LLC) cells-inoculated mice model. We discovered that administration of fucoidan has prophylactic effects on mitigation of cachectic body weight loss and improvement of lung masses in tumor-inoculated mice. These desired effects are attributed to inhibition of LLC spreading and proliferation in lung tissues. Fucoidan also down-regulates expression of matrix metalloproteinases (MMPs), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and vascular endothelial growth factor (VEGF). Moreover, the tumor-bearing mice supplemented with fucoidan indeed benefit from an ensemble of the chemo-phylacticity. The fact is that fucoidan significantly decreases viability, migration, invasion, and MMPs activities of LLC cells. In summary, fucoidan is suitable to act as a chemo-preventative agent for minimizing cachectic symptoms as well as inhibiting lung carcinoma metastasis through down-regulating metastatic factors VEGF and MMPs.

Epigenetic silencing of microRNA-203 is required for EMT and cancer stem cell properties

The epithelial-mesenchymal transition (EMT) imparts metastatic competence on otherwise non-metastatic cancer cells through decreased inter-cellular adhesions, increased migratory capacity, stem cell properties and anoikis and chemotherapy resistance. In this study, we profiled changes in microRNA expression during EMT in conjunction with changes in DNA methylation at microRNA promoters to discover essential mediators of EMT-imparted stemness properties. MicroRNA-203 (miR-203) expression is repressed following EMT induced by multiple different stimuli and in established claudin-low cell lines as well as the CD44hi/CD24lo stem cell-enriched fraction. Expression of miR-203 in mesenchymal cells compromises migratory and invasive capacity in vitro, and tumor initiation and metastasis in vivo. Unexpectedly, miR-203 expression affects the sphere-forming capacity of neighboring cells by indirectly enhancing expression of DKK1, a secreted inhibitor of Wnt signaling and stemness resulting in suppression of β-catenin protein levels. Our data suggest that restoring miR-203 expression levels may inhibit metastasis and combat deregulated Wnt signaling.