Patterns of metastasis in human solid cancers

Identification of cytokeratin24 as a tumor suppressor for the management of head and neck cancer

To improve management of head and neck squamous cell carcinoma patients, we need to increase our understanding of carcinogenesis, to identify biomarkers, and drug targets. This study aimed to identify novel biomarkers by providing transcriptomics profiles of matched primary tumors, lymph node metastasis, and non-malignant tissue of 20 HNSCC patients as well as by bioinformatic analyses of a TCGA HNSCC cohort, comprising 554 patients. We provide cancer cell signaling networks differentially expressed in tumors versus metastases, such as mesenchymal-epithelial transition, and structural integrity networks. As a proof of principle study, we exploited the data sets and performed functional analyses of a novel cytokeratin, cytokeratin24 (cKRT24), which had not been described as biomarker for tumors before. Survival analysis revealed that low cKRT24 expression correlated with poor overall survival in HNSCC. Experimentally, downregulation of cKRT24 in primary tumors, metastases, and HNSCC cell lines was verified on mRNA and protein level. Cloning and ectopic overexpression of cKRT24 not only affected viability and growth of HNSSC cell lines, but also inhibited tumor growth in murine xenograft studies. We conclude that cKRT24 functions as a tumor suppressor in HNSCC, and may serve as an additional prognostic biomarker and novel target to support current HNSCC treatments.

Accumulation of small hyaluronan oligosaccharides in tumour interstitial fluid correlates with lymphatic invasion and lymph node metastasis

BACKGROUND

Association studies have implicated the glycosaminoglycan hyaluronan (hyaluronic acid, HA) and its degrading enzymes the hyaluronidases in tumour progression and metastasis. Oligosaccharides of degraded HA have been ascribed a number of biological functions that are not exerted by high-molecular-weight HA (HMW-HA). However, whether these small HA oligosaccharides (sHA) have a role in tumour progression currently remains uncertain due to an inability to analyse their concentration in tumours.

METHODS

We report a novel method to determine the concentration of sHA ranging from 6 to 25 disaccharides in tumour interstitial fluid (TIF). Levels of sHA were measured in TIF from experimental rat tumours and human colorectal tumours.

RESULTS

While the majority of HA in TIF is HMW-HA, concentrations of sHA up to 6 μg ml(-1) were detected in a subset of tumours, but not in interstitial fluid from healthy tissues. In a cohort of 72 colorectal cancer patients we found that increased sHA concentrations in TIF are associated with lymphatic vessel invasion by tumour cells and the formation of lymph node metastasis.

CONCLUSIONS

These data document for the first time the pathophysiological concentration of sHA in tumours, and provide evidence of a role for sHA in tumour progression.

Characterization of metastasis formation and virotherapy in the human C33A cervical cancer model

More than 90% of cancer mortalities are due to cancer that has metastasized. Therefore, it is crucial to intensify research on metastasis formation and therapy. Here, we describe for the first time the metastasizing ability of the human cervical cancer cell line C33A in athymic nude mice after subcutaneous implantation of tumor cells. In this model, we demonstrated a steady progression of lumbar and renal lymph node metastases during tumor development. Besides predominantly occurring lymphatic metastases, we visualized the formation of hematogenous metastases utilizing red fluorescent protein (RFP) expressing C33A-RFP cells. RFP positive cancer cells were found migrating in blood vessels and forming micrometastases in lungs of tumor-bearing mice. Next, we set out to analyze the influence of oncolytic virotherapy in the C33A-RFP model and demonstrated an efficient virus-mediated reduction of tumor size and metastatic burden. These results suggest the C33A-RFP cervical cancer model as a new platform to analyze cancer metastases as well as to test novel treatment options to combat metastases.

Differential survival trends of stage II colorectal cancer patients relate to promoter methylation status of PCDH10, SPARC, and UCHL1

Surgical excision of colorectal cancer at early clinical stages is highly effective, but 20-30% of patients relapse. Therefore, it is of clinical relevance to identify patients at high risk for recurrence, who would benefit from adjuvant chemotherapy. The objective of this study was to identify prognostic and/or predictive methylation markers in stage II colorectal cancer patients. Therefore, we selected six gene promoters (FZD9, PCDH10 (protocadherin 10), SFRP2, SPARC (secreted protein acidic and rich in cysteine), UCHL1 (ubiquitin carboxyl-terminal hydrolase 1), and WIF1) for methylation analysis in formalin-fixed, paraffin-embedded primary tumor samples of colorectal cancer patients (n=143) who were enrolled in a prospective randomized phase III trial of the Austrian Breast and Colorectal cancer Study Group. Patients were randomized to adjuvant chemotherapy with 5-fluorouracil and leucovorin or surveillance only. Survival analyses revealed that combined evaluation of three promoters (PCDH10, SPARC, and UCHL1) showed differential effects with regard to disease-free survival and overall survival in the two treatment groups (significance level 0.007). In the chemotherapy arm, a statistically insignificant trend for patients without methylation toward longer survival was observed (P=0.069 for disease-free survival and P=0.139 for overall survival). Contrary, patients in the surveillance arm without methylation in their gene promoters had shorter disease-free survival and overall survival (P=0.031 for disease-free survival and P=0.003 for overall survival), indicating a prognostic effect of methylation in this group (test for interaction, P=0.006 for disease-free survival and P=0.018 for overall survival). These results indicate that promoter methylation status of PCDH10, SPARC, and UCHL1 may be used both as prognostic and predictive molecular marker for colorectal cancer patients and, therefore, may facilitate treatment decisions for stage II colorectal cancer.