Heterogeneity of mesenchymal markers expression-molecular profiles of cancer cells disseminated by lymphatic and hematogenous routes in breast cancer

Comparison of circulating tumor cell (CTC) detection rates with epithelial cell adhesion molecule (EpCAM) and cell surface vimentin (CSV) antibodies in different solid tumors: a retrospective study

Purpose

Status of epithelial-mesenchymal transition (EMT) varies from tumors to tumors. Epithelial cell adhesion molecule (EpCAM) and cell surface vimentin (CSV) are the most common used targets for isolating epithelial and mesenchymal CTCs, respectively. This study aimed to identify a suitable CTC capturing antibody for CTC enrichment in each solid tumor by comparing CTC detection rates with EpCAM and CSV antibodies in different solid tumors.

Methods

Treatment-naive patients with confirmed cancer diagnosis and healthy people who have performed CTC detection between April 2017 and May 2018 were included in this study. CTC detection was performed with CytoSorter^® CTC system using either EpCAM or CSV antibody. In total, 853 CTC results from 690 cancer patients and 72 healthy people were collected for analysis. The performance of CTC capturing antibody was determined by the CTC detection rate.

Results

EpCAM has the highest CTC detection rate of 84.09% in CRC, followed by BCa (78.32%). CTC detection rates with EpCAM antibody are less than 40% in HCC (25%), PDAC (32.5%) and OC (33.33%). CSV has the highest CTC detection rate of 90% in sarcoma, followed by BC (85.71%), UC (84.62%), OC (83.33%) and BCa (81.82%). CTC detection rates with CSV antibody are over 60% in all 14 solid tumors. Except for CRC, CSV has better performances than EpCAM in most solid tumors regarding the CTC detection rates.

Conclusion

EpCAM can be used as a target to isolate CTCs in CRC, LC, GC, BCa, EC, HNSCC, CC and PCa, especially in CRC, while CSV can be used in most solid tumors for isolating CTCs.

"Stealth dissemination" of macrophage-tumor cell fusions cultured from blood of patients with pancreatic ductal adenocarcinoma

Here we describe isolation and characterization of macrophage-tumor cell fusions (MTFs) from the blood of pancreatic ductal adenocarcinoma (PDAC) patients. The MTFs were generally aneuploidy, and immunophenotypic characterizations showed that the MTFs express markers characteristic of PDAC and stem cells, as well as M2-polarized macrophages. Single cell RNASeq analyses showed that the MTFs express many transcripts implicated in cancer progression, LINE1 retrotransposons, and very high levels of several long non-coding transcripts involved in metastasis (such as MALAT1). When cultured MTFs were transplanted orthotopically into mouse pancreas, they grew as obvious well-differentiated islands of cells, but they also disseminated widely throughout multiple tissues in "stealth" fashion. They were found distributed throughout multiple organs at 4, 8, or 12 weeks after transplantation (including liver, spleen, lung), occurring as single cells or small groups of cells, without formation of obvious tumors or any apparent progression over the 4 to 12 week period. We suggest that MTFs form continually during PDAC development, and that they disseminate early in cancer progression, forming "niches" at distant sites for subsequent colonization by metastasis-initiating cells.

The Effect of a Histone Deacetylase Inhibitor (AR-42) on Canine Prostate Cancer Growth and Metastasis

BACKGROUND

Canine prostate cancer (PCa) is an excellent preclinical model for human PCa. AR-42 is a histone deacetylase inhibitor (HDACi) developed at The Ohio State University that inhibits the proliferation of several cancers, including multiple myeloma, lung, and hepatocellular cancer. In this study, we investigated whether AR-42 would prevent or decrease. The growth and metastasis of a canine PCa (Ace-1 cells) to bone in vitro and in vivo.

METHODS

Proliferation, cell viability, invasion, and metastasis of a canine prostate cancer cell line (Ace-1) were measured following treatment with AR-42. Expression of anoikis resistance, epithelial-to-mesenchymal transition (EMT), and stem cell-related markers were also evaluated. To assess the efficacy of AR-42 on prevention of PCa metastasis to bone, Ace-1 cells were injected in the left cardiac ventricle of nude mice, mice were treated with AR-42, and the incidence and growth of bone metastasis were measured. Bioluminescence was performed to monitor the bone metastases in nude mice.

RESULTS

AR-42 inhibited the in vitro proliferation of Ace-1 cells in a time- and dose-dependent manner. The IC₅₀ concentration of AR-42 for Ace-1 cells was 0.42 μM after 24 hr of treatment. AR-42 induced apoptosis, decreased cell migration, and increased the stem cell properties of Ace-1 cells in vitro. AR-42 downregulated E-cadherin, N-cadherin, TWIST, MYOF, anoikis resistance, and osteomimicry genes, while it upregulated SNAIL, PTEN, FAK, and ZEB1 gene expression in Ace-1 cells. Importantly, AR-42 decreased the bioluminescence and incidence of bone metastasis in nude mice. In addition, AR-42 induced apoptosis and altered the tumor cell morphology to an irregular cell phenotype with condensed chromatin in the bone metastases.

CONCLUSION

AR-42 decreased PCa growth and bone metastasis, induced apoptosis, and downregulated osteomimicry genes in PCa cells in the bone microenvironment. Prostate 77:776-793, 2017. © 2017 Wiley Periodicals, Inc.

Long-term disease stabilization following treatment with erlotinib in heavily pretreated patients with wild-type epidermal growth factor receptor non-small-cell lung carcinoma: Two case reports

Lung adenocarcinomas carrying epidermal growth factor receptor (EGFR) mutations have been identified as a unique group of entities that depend on EGFR for their proliferation and metastasis. The introduction of reversible EGFR tyrosine kinase inhibitors, such as erlotinib, has significantly affected the management of metastatic disease in this subset of patients. Interestingly, although erlotinib is highly effective in patients with EGFR mutations, it may occasionally prove useful, even in the absence of mutations. We herein present the course of two heavily pretreated patients who achieved remarkable disease stabilization over several years, despite harbouring no EGFR mutations. Our cases underscore the fact that further research is required to identify which subset of patients will benefit the most from this treatment, as a substantial minority may present with favourable outcomes.

Macrophage-tumor cell fusions from peripheral blood of melanoma patients

Background

While the morbidity and mortality from cancer are largely attributable to its metastatic dissemination, the integral features of the cascade are not well understood. The widely accepted hypothesis is that the primary tumor microenvironment induces the epithelial-to-mesenchymal transition in cancer cells, facilitating their escape into the bloodstream, possibly accompanied by cancer stem cells. An alternative theory for metastasis involves fusion of macrophages with tumor cells (MTFs). Here we culture and characterize apparent MTFs from blood of melanoma patients.

Methods

We isolated enriched CTC populations from peripheral blood samples from melanoma patients, and cultured them. We interrogated these cultured cells for characteristic BRAF mutations, and used confocal microscopy for immunophenotyping, motility, DNA content and chromatin texture analyses, and then conducted xenograft studies using nude mice.

Findings

Morphologically, the cultured MTFs were generally large with many pseudopod extensions and lamellipodia. Ultrastructurally, the cultured MTFs appeared to be macrophages. They were rich in mitochondria and lysosomes, as well as apparent melanosomes. The cultured MTF populations were all heterogeneous with regard to DNA content, containing aneuploid and/or high-ploidy cells, and they typically showed large sheets (and/or clumps) of cytoplasmic chromatin. This cytoplasmic DNA was found within heterogeneously-sized autophagic vacuoles, which prominently contained chromatin and micronuclei. Cultured MTFs uniformly expressed pan-macrophage markers (CD14, CD68) and macrophage markers indicative of M2 polarization (CD163, CD204, CD206). They also expressed melanocyte-specific markers (ALCAM, MLANA), epithelial biomarkers (KRT, EpCAM), as well as the pro-carcinogenic cytokine MIF along with functionally related stem cell markers (CXCR4, CD44). MTF cultures from individual patients (5 of 8) contained melanoma-specific BRAF activating mutations. Chromatin texture analysis of deconvoluted images showed condensed DNA (DAPI-intense) regions similar to focal regions described in stem cell fusions. MTFs were readily apparent in vivo in all human melanomas examined, often exhibiting even higher DNA content than the cultured MTFs. When cultured MTFs were transplanted subcutaneously in nude mice, they disseminated and produced metastatic lesions at distant sites.

Conclusions and Hypothesis

Apparent MTFs are present in peripheral blood of patients with cutaneous melanomas, and they possess the ability to form metastatic lesions when transplanted into mice. We hypothesize that these MTFs arise at the periphery of primary tumors in vivo, that they readily enter the bloodstream and invade distant tissues, secreting cytokines (such as MIF) to prepare “niches” for colonization by metastasis initiating cells.

Epithelial-mesenchymal transition markers in lymph node metastases and primary breast tumors - relation to dissemination and proliferation

Epithelial-mesenchymal transition (EMT) was shown to enhance metastatic abilities of cancer cells, but it remains elusive in clinical samples. Moreover, EMT is rarely studied in lymph node metastases (LNM), thus limiting our understanding of its role outside of the primary tumors (PT). We collected a set of samples including triplets - PT, circulating tumor cells (CTCs)-enriched blood samples and LNM from 108 early breast cancer patients. With immunohistochemistry we analyzed levels of EMT effectors - E-cadherin, vimentin and N-cadherin in LNM, central areas and margins of PT. Additionally, expression of EMT core regulators TWIST1, SNAI1, SNAI2 was measured with RT-qPCR. Patients with E-cadherin loss had CTCs in 45% of the cases in comparison to 23% with normal E-cadherin level (P = 0.05). Mesenchymal phenotype of CTCs-enriched blood fractions was five-times more frequent in patients with E-cadherin loss in PT compared to PT with normal E-cadherin levels (P = 0.01). Epithelial/mesenchymal status of matched samples at different stages of dissemination was frequently discordant, especially for pairs involving CTCs, indicating high plasticity of tumor cells. LNM showed increased expression of TWIST1, SNAI1, SNAI2 accompanied by decreased Ki67 labeling index, with median Ki67 of 15% in PT and 10% in LNM (P = 0.0002). Our findings demonstrate that E-cadherin loss, not only in PT margin, might lead to seeding of especially malignant CTCs with mesenchymal phenotype. In comparison to PT, cells in LNM re-express E-cadherin, upregulate EMT transcription factors and reduce cell division rate, which could be viewed as their long-term survival strategy.

Mesenchymal phenotype of CTC-enriched blood fraction and lymph node metastasis formation potential

Introduction

Circulating tumor cells (CTCs) that present mesenchymal phenotypes can escape standard methods of isolation, thus limiting possibilities for their characterization. Whereas mesenchymal CTCs are considered to be more malignant than epithelial CTCs, factors responsible for this aggressiveness have not been thoroughly defined. This study analyzed the molecular profile related to metastasis formation potential of CTC-enriched blood fractions obtained by marker unbiased isolation from breast cancer patients without (N−) and with lymph nodes metastases (N+).

Materials and Methods

Blood samples drawn from 117 patients with early-stage breast cancer were enriched for CTCs using density gradient centrifugation and negative selection with anti-CD45 covered magnetic particles. In the resulting CTC-enriched blood fractions, expression of CK19, MGB1, VIM, TWIST1, SNAIL, SLUG, HER2, CXCR4 and uPAR was analyzed with qPCR. Results were correlated with patients' clinicopathological data.

Results

CTCs (defined as expression of either CK19, MGB1 or HER2) were detected in 41% (20/49) of N− and 69% (34/49) of N+ patients (P = 0.004). CTC-enriched blood fractions of N+ patients were more frequently VIM (P = 0.02), SNAIL (P = 0.059) and uPAR-positive (P = 0.03). Positive VIM, CXCR4 and uPAR status correlated with >3 lymph nodes involved (P = 0.003, P = 0.01 and P = 0.045, respectively). In the multivariate logistic regression MGB1 and VIM-positivity were independently related to lymph node involvement with corresponding overall risk of 3.2 and 4.2. Moreover, mesenchymal CTC-enriched blood fractions (CK19−/VIM+ and MGB1+ or HER2+) had 4.88 and 7.85-times elevated expression of CXCR4 and uPAR, respectively, compared with epithelial CTC-enriched blood fractions (CK19+/VIM− and MGB1+ or HER2+).

Conclusions

Tumors of N+ patients have superior CTC-seeding and metastatic potential compared with N- patients. These differences can be attributed to VIM, uPAR and CXCR4 expression, which endow tumor cells with particularly malignant phenotypes.