The origin of intestinal cancer in the context of inflammation

According to conventional views, colon cancer originates from stem cells. However, inflammation, a key risk factor for colon cancer, was shown to suppress intestinal stemness. Here, we employed Paneth cells (PCs) as a model to assess the capacity of differentiated lineages to trigger tumorigenesis in the context of inflammation. Upon inflammation, PC-specific Apc mutations led to intestinal tumors reminiscent not only of those arising in inflammatory bowel disease (IBD) patients but also of a larger fraction of sporadic colon cancers. The latter is likely due to the inflammatory consequences of Western-style dietary habits, the major colon cancer risk factor. Computational methods designed to predict the cell-of-origin of cancer confirmed that, in a substantial fraction of sporadic colon cancers the cells-of-origin are secretory lineages and not stem cells.

The deleted in oral cancer (DOC1 aka CDK2AP1) tumor suppressor gene is downregulated in oral squamous cell carcinoma by multiple microRNAs

Cyclin-dependent kinase 2-associated protein 1 (CDK2AP1; also known as deleted in oral cancer or DOC1) is a tumor suppressor gene known to play functional roles in both cell cycle regulation and in the epigenetic control of embryonic stem cell differentiation, the latter as a core subunit of the nucleosome remodeling and histone deacetylation (NuRD) complex. In the vast majority of oral squamous cell carcinomas (OSCC), expression of the CDK2AP1 protein is reduced or lost. Notwithstanding the latter (and the DOC1 acronym), mutations or deletions in its coding sequence are extremely rare. Accordingly, CDK2AP1 protein-deficient oral cancer cell lines express as much CDK2AP1 mRNA as proficient cell lines. Here, by combining in silico and in vitro approaches, and by taking advantage of patient-derived data and tumor material in the analysis of loss of CDK2AP1 expression, we identified a set of microRNAs, namely miR-21-5p, miR-23b-3p, miR-26b-5p, miR-93-5p, and miR-155-5p, which inhibit its translation in both cell lines and patient-derived OSCCs. Of note, no synergistic effects were observed of the different miRs on the CDK2AP1-3-UTR common target. We also developed a novel approach to the combined ISH/IF tissue microarray analysis to study the expression patterns of miRs and their target genes in the context of tumor architecture. Last, we show that CDK2AP1 loss, as the result of miRNA expression, correlates with overall survival, thus highlighting the clinical relevance of these processes for carcinomas of the oral cavity.

Mesenchymal-epithelial transition factor (MET) immunoreactivity in positive sentinel nodes from patients with melanoma

OBJECTIVE

Patients with cutaneous melanoma and a positive sentinel node (SN) are currently eligible for adjuvant treatment with targeted therapy and immune checkpoint inhibitors. Near-infrared (NIR) fluorescence imaging could be an alternative and less invasive tool for SN biopsy to select patients for adjuvant treatment. One potential target for NIR is the mesenchymal-epithelial transition factor (MET). This study aimed to assess MET immunoreactivity in positive SNs and to evaluate its potential diagnostic, prognostic and therapeutic value.

METHODS

In this retrospective study, positive SN samples from patients with primary cutaneous melanoma were collected to assess MET immunoreactivity. To this end, paraffin-embedded SNs were stained for MET (monoclonal antibody D1C2). A 4-point Histoscore was used to determine cytoplasmic and membranous immunoreactivity (0 negative/1 weak/2 moderate/3 strong). Samples were considered positive when ≥10% of the cancer cells showed MET expression (staining intensity ≥1). Patient and clinicopathological characteristics were used for descriptive statistics, binary logistic regression, and survival analyses.

RESULTS

Positive MET immunohistochemistry was observed in 24 out of 37 samples (65%). No statistically significant associations were found between MET positivity and the following prognostic factors: Breslow thickness (P = 0.961), ulceration (P = 1.000), and SN tumor burden (P = 0.792). According to MET positivity, Kaplan-Meier curves showed no significant differences in survival.

CONCLUSION

This exploratory study found no evidence to support MET immunoreactivity in positive SNs as a possible diagnostic or prognostic indicator in patients with melanoma.

The Occurrence of MET Ectodomain Shedding in Oral Cancer and Its Potential Impact on the Use of Targeted Therapies

Simple Summary

Head and neck cancer is the sixth most common cancer type worldwide, comprising tumors of the upper aero/digestive tract. Approximately 50% of these cancers originate in the oral cavity. Depending on disease stage, oral cancer patients are treated with single-modality surgery, or in combination with radiotherapy with or without chemotherapy. Despite advances in these modalities, the 5-year survival rate is merely 50%. Therefore, implementation of targeted therapies, directed against signaling molecules, has gained attention. One potential target is the MET protein, which can be present on the surface of cancer cells, orchestrating aggressive behavior. As cancer cells can shed the extracellular part of MET from their surface, it is important to identify for MET positive patients whether they possess the entire and/or only the intracellular part of the receptor to assess whether targeted therapies directed against the extracellular, intracellular, or both parts of MET need to be implemented.

Abstract

The receptor tyrosine kinase MET has gained attention as a therapeutic target. Although MET immunoreactivity is associated with progressive disease, use of targeted therapies has not yet led to major survival benefits. A possible explanation is the lack of companion diagnostics (CDx) that account for proteolytic processing. During presenilin-regulated intramembrane proteolysis, MET’s ectodomain is shed into the extracellular space, which is followed by γ-secretase-mediated cleavage of the residual membranous C-terminal fragment. The resulting intracellular fragment is degraded by the proteasome, leading to downregulation of MET signaling. Conversely, a membrane-bound MET fragment lacking the ectodomain (MET-EC^-) can confer malignant potential. Use of C- and N-terminal MET monoclonal antibodies (moAbs) has illustrated that MET-EC^- occurs in transmembranous C-terminal MET-positive oral squamous cell carcinoma (OSCC). Here, we propose that ectodomain shedding, resulting from G-protein-coupled receptor transactivation of epidermal growth factor receptor signaling, and/or overexpression of ADAM10/17 and/or MET, stabilizes and possibly activates MET-EC^- in OSCC. As MET-EC^- is associated with poor prognosis in OSCC, it potentially has impact on the use of targeted therapies. Therefore, MET-EC^- should be incorporated in the design of CDx to improve patient stratification and ultimately prolong survival. Hence, MET-EC^- requires further investigation seen its oncogenic and predictive properties.

Phenotypic plasticity underlies local invasion and distant metastasis in colon cancer

Phenotypic plasticity represents the most relevant hallmark of the carcinoma cell as it bestows it with the capacity of transiently altering its morphological and functional features while en route to the metastatic site. However, the study of phenotypic plasticity is hindered by the rarity of these events within primary lesions and by the lack of experimental models. Here, we identified a subpopulation of phenotypic plastic colon cancer cells: EpCAMlo cells are motile, invasive, chemo-resistant, and highly metastatic. EpCAMlo bulk and single-cell RNAseq analysis indicated (1) enhanced Wnt/β-catenin signaling, (2) a broad spectrum of degrees of epithelial to mesenchymal transition (EMT) activation including hybrid E/M states (partial EMT) with highly plastic features, and (3) high correlation with the CMS4 subtype, accounting for colon cancer cases with poor prognosis and a pronounced stromal component. Of note, a signature of genes specifically expressed in EpCAMlo cancer cells is highly predictive of overall survival in tumors other than CMS4, thus highlighting the relevance of quasi-mesenchymal tumor cells across the spectrum of colon cancers. Enhanced Wnt and the downstream EMT activation represent key events in eliciting phenotypic plasticity along the invasive front of primary colon carcinomas. Distinct sets of epithelial and mesenchymal genes define transcriptional trajectories through which state transitions arise. pEMT cells, often earmarked by the extracellular matrix glycoprotein SPARC together with nuclear ZEB1 and β-catenin along the invasive front of primary colon carcinomas, are predicted to represent the origin of these (de)differentiation routes through biologically distinct cellular states and to underlie the phenotypic plasticity of colon cancer cells.

The Potential of MET Immunoreactivity for Prediction of Lymph Node Metastasis in Early Oral Tongue Squamous Cell Carcinoma

Objective

MET positivity is independently associated with survival in oral squamous cell carcinoma (OSCC). Since MET is a known orchestrator of invasive tumor growth, we investigated its association with LNM in early oral tongue squamous cell carcinoma (OTSCC). As it is recommended by the NCCN to use tumor depth of invasion (DOI) in making decisions on elective neck dissection (END), the results obtained for MET positivity were aligned with those for DOI > 4 mm. The cutoff value used in our institution.

Methods

Tumor samples from patients who underwent primary tumor resection and neck dissection between 1995 and 2013, were collected from the archives of the Leiden and Erasmus University Medical Center. Immunohistochemistry with D1C2 was performed to identify MET negative (< 10% uniform positivity) and MET positive (≥ 10% uniform positivity) cancers. ROC curve analysis and the Chi-squared test were used to investigate the association of MET positivity with LNM (pN+ and occult). Binary logistic regression was used to investigate the association of MET positivity with LNM.

Results

Forty-five (44.1%) of the 102 cancers were MET positive. Ninety were cN0 of which 20 were pN+ (occult metastasis). The remaining 12 cancers were cN+, of which 10 were proven pN+ and 2 were pN0. MET positivity was associated with LNM with a positive predictive value (PPV) of 44.4% and a negative predictive value (NPV) of 82.5% for pN+. For the occult group, the PPV was 36.8% and the NPV was 88.5%. Regression analysis showed that MET positivity is associated with pN+ and occult LNM (p-value < 0.05).

Conclusion

MET positivity is significantly associated with LNM in early OTSCC, outperforming DOI. The added value of MET positivity could be in the preoperative setting when END is being considered during the initial surgery. For cases with DOI ≤ 4 mm, MET positivity could aid in the clinical decision whether regular follow-up, watchful waiting, or END is more appropriate. Realizing that these preliminary results need to be independently validated in a larger patient cohort, we believe that MET positivity could be of added value in the decision making on END in early OTSCC.

The unveiled reality of human papillomavirus as risk factor for oral cavity squamous cell carcinoma

The prognostic impact of human papillomavirus (HPV) in oropharyngeal cancer is generally acknowledged, and HPV-status is assessed routinely in clinical practice. Paradoxically, while the oral cavity seems the predilection site for productive HPV-infections, figures on HPV-attribution in oral cavity squamous cell carcinoma (OCSCC) differ widely, and prognostic impact is uncertain. Major obstacles are the lack of reproducible assays to detect HPV in nonoropharyngeal cancers, the relatively small cohorts studied and consequently the shortfall of convincing data. In our study, we used a validated, nucleic acid-based workflow to assess HPV-prevalence in a consecutive cohort of 1016 OCSCCs, and investigated its prognostic impact. In parallel, we analyzed p16-immunohistochemistry (p16-IHC) as surrogate marker for transforming HPV-infection and independent prognosticator. All OCSCC-patients diagnosed between 2008 and 2014 at two Dutch university medical centers were included (N = 1069). Formalin-fixed, paraffin-embedded (FFPE)-samples of 1016 OCSCCs could be retrieved. Punch biopsies were taken from the tumor area in the FFPE-blocks and tested for HPV. P16-IHC was performed on 580 OCSCCs, including all HPV-positive tumors. From 940 samples (92.5%), nucleic acids were of sufficient quality for HPV-testing. In total, 21 (2.2%) OCSCCs were HPV DNA-positive. All HPV DNA-positive tumors were E6 mRNA-positive and considered as true HPV-positive. There was no difference in survival between HPV-positive and HPV-negative OCSCCs. In total, 46 of 580 (7.9%) OCSCCs were p16-immunopositive, including all HPV-positive tumors. Survival was comparable in p16-positive and p16-negative OCSCCs. To conclude, HPV-prevalence is very low in OCSCC and neither HPV-status nor p16-status affects outcome. Based on these data, determining HPV-status in OCSCC seems irrelevant for clinical management.

Is the Depth of Invasion a Marker for Elective Neck Dissection in Early Oral Squamous Cell Carcinoma?

Objective

The depth of invasion (DOI) is considered an independent risk factor for occult lymph node metastasis in oral cavity squamous cell carcinoma (OCSCC). It is used to decide whether an elective neck dissection (END) is indicated in the case of a clinically negative neck for early stage carcinoma (pT1/pT2). However, there is no consensus on the cut-off value of the DOI for performing an END. The aim of this study was to determine a cut-off value for clinical decision making on END, by assessing the association of the DOI and the risk of occult lymph node metastasis in early OCSCC.

Methods

A retrospective cohort study was conducted at the Erasmus MC, University Medical Centre Rotterdam, The Netherlands. Patients surgically treated for pT1/pT2 OCSCC between 2006 and 2012 were included. For all cases, the DOI was measured according to the 8^th edition of the American Joint Committee on Cancer guideline. Patient characteristics, tumor characteristics (pTN, differentiation grade, perineural invasion, and lymphovascular invasion), treatment modality (END or watchful waiting), and 5-year follow-up (local recurrence, regional recurrence, and distant metastasis) were obtained from patient files.

Results

A total of 222 patients were included, 117 pT1 and 105 pT2. Occult lymph node metastasis was found in 39 of the 166 patients who received END. Univariate logistic regression analysis showed DOI to be a significant predictor for occult lymph node metastasis (odds ratio (OR) = 1.3 per mm DOI; 95% CI: 1.1-1.5, p = 0.001). At a DOI of 4.3 mm the risk of occult lymph node metastasis was >20% (all subsites combined).

Conclusion

The DOI is a significant predictor for occult lymph node metastasis in early stage oral carcinoma. A NPV of 81% was found at a DOI cut-off value of 4 mm. Therefore, an END should be performed if the DOI is >4 mm.

A novel immunohistochemical scoring system reveals associations of C-terminal MET, ectodomain shedding, and loss of E-cadherin with poor prognosis in oral squamous cell carcinoma

Using tissue microarrays, it was shown that membranous C-terminal MET immunoreactivity and ectodomain (ECD) shedding are associated with poor prognosis in oral cancer. Seen the potential diagnostic value, extrapolation of these results to whole-tissue sections was investigated. Because MET orchestrates epithelial-to-mesenchymal transition (EMT), the results were benchmarked to loss of E-cadherin, a readout for EMT known to be associated with poor prognosis. C-terminal MET, N-terminal MET, and E-cadherin immunoreactivities were examined on formalin-fixed paraffin-embedded parallel sections of 203 oral cancers using antibody clones D1C2, A2H2-3, and NCH-38. Interantibody and intra-antibody relations were examined using a novel scoring system, nonparametric distribution, and median tests. Survival analyses were used to examine the prognostic value of the observed immunoreactivities. Assessment of the three clones revealed MET protein status (no, decoy, transmembranous C-terminal positive), ECD shedding, and EMT. For C-terminal MET-positive cancers, D1C2 immunoreactivity is independently associated with poor overall survival (hazard ratio [HR] = 2.40; 95% confidence interval [CI] = 1.25 to 4.61; and P = 0.008) and disease-free survival (HR = 1.83; 95% CI = 1.07-3.14; P = 0.027). For both survival measures, this is also the case for ECD shedding (43.4%, with HR = 2.30; 95% CI = 1.38 to 3.83; and P = 0.001 versus HR = 1.87; 95% CI = 1.19-2.92; P = 0.006) and loss of E-cadherin (55.3%, with HR = 2.21; 95% CI = 1.30 to 3.77; and P = 0.004 versus HR = 1.90; 95% CI = 1.20-3.01; P = 0.007). The developed scoring system accounts for MET protein status, ECD shedding, and EMT and is prognostically informative. These findings may contribute to development of companion diagnostics for MET-based targeted therapy.

MET expression during prostate cancer progression

Tyrosine-kinase inhibitors of the hepatocyte growth factor receptor MET are under investigation for the treatment of hormone-refractory prostate cancer (HRPC) metastasis. Analysis of MET protein expression and genetic alterations might contribute to therapeutic stratification of prostate cancer patients. Our objective was to investigate MET on protein, DNA and RNA level in clinical prostate cancer at various stages of progression.

Expression of MET was analyzed in hormone-naive primary prostate cancers (N=481), lymph node (N=40) and bone (N=8) metastases, as well as HRPC (N=54) and bone metastases (N=15). MET protein expression was analyzed by immunohistochemistry (D1C2 C-terminal antibody). MET mRNA levels and MET DNA copy numbers were determined by in situ hybridization.

None of the hormone-naive primary prostate cancer or lymph node metastases demonstrated MET protein or mRNA expression. In contrast, MET protein was expressed in 12/52 (23%) evaluable HRPC resections. RNA in situ demonstrated cytoplasmic signals in 14/54 (26%) of the HRPC patients, and was associated with MET protein expression (p=0.025, χ²), in absence of MET amplification or polysomy. MET protein expression was present in 7/8 (88%) hormone-naive and 10/15 (67%) HRPC bone metastases, without association of HRPC (p=0.37; χ²), with MET polysomy in 8/13 (61%) evaluable cases.

In conclusion, MET was almost exclusively expressed in HRPC and prostate cancer bone metastasis, but was not related to MET amplification or polysomy. Evaluation of MET status could be relevant for therapeutic stratification of late stage prostate cancer.