Mechanisms of malignant progression

Initiation of Cancer: The Journey From Mutations in Somatic Cells to Epigenetic Changes in Tissue-resident VSELs

Multiple theories exist to explain cancer initiation, although a consensus on this is crucial for developing effective therapies. 'Somatic mutation theory' suggests that mutations in somatic cells during DNA repair initiates cancer but this concept has several attached paradoxes. Research efforts to identify quiescent cancer stem cells (CSCs) that survive therapy and result in metastasis and recurrence have remained futile. In solid cancers, CSCs are suggested to appear during epithelial-mesenchymal transition by the dedifferentiation and reprogramming of epithelial cells. Pluripotent and quiescent very small embryonic-like stem cells (VSELs) exist in multiple tissues but remain elusive owing to their small size and scarce nature. VSELs are developmentally connected to primordial germ cells, undergo rare, asymmetrical cell divisions and are responsible for the regular turnover of cells to maintain tissue homeostasis throughout life. VSELs are directly vulnerable to extrinsic endocrine insults because they express gonadal and gonadotropin hormone receptors. VSELs undergo epigenetic changes due to endocrine insults and transform into CSCs. CSCs exhibit genomic instability and develop mutations due to errors during DNA replication while undergoing excessive proliferation and clonal expansion to form spheroids. Thus tissue-resident VSELs offer a connection between extrinsic insults and variations in cancer incidence reported in various body tissues. To conclude, cancer is indeed a stem cell disease with mutations occurring as a consequence. In addition to immunotherapy, targeting mutations, and Lgr5 + organoids for developing new therapeutics, targeting CSCs (epigenetically altered VSELs) by improving their niche and epigenetic status could serve as a promising strategy to treat cancer.

Dissemination of Circulating Tumor Cells in Breast and Prostate Cancer: Implications for Early Detection

Burgeoning evidence suggests that circulating tumor cells (CTCs) may disseminate into blood vessels at an early stage, seeding metastases in various cancers such as breast and prostate cancer. Simultaneously, the early-stage CTCs that settle in metastatic sites [termed disseminated tumor cells (DTCs)] can enter dormancy, marking a potential source of late recurrence and therapy resistance. Thus, the presence of these early CTCs poses risks to patients but also holds potential benefits for early detection and treatment and opportunities for possibly curative interventions. This review delves into the role of early DTCs in driving latent metastasis within breast and prostate cancer, emphasizing the importance of early CTC detection in these diseases. We further explore the correlation between early CTC detection and poor prognoses, which contribute significantly to increased cancer mortality. Consequently, the detection of CTCs at an early stage emerges as a critical imperative for enhancing clinical diagnostics and allowing for early interventions.

Impact of regional lymph node metastasis on pulmonary metastasis as the first recurrence site

Little is known about the impact of regional lymph node metastasis (LNM) on the first recurrence sites following curative colorectal cancer (CRC) surgery. The present study aimed to clarify the relationship between regional LNM stratified by N status and the first recurrence pattern in patients with stage I-III CRC. We performed a retrospective analysis of 1181 consecutive patients with stage I-III CRC who underwent curative surgery between 2010 and 2018. The total sample size included 1181 patients who underwent elective stage I-III CRC surgery. Median follow-up time was 60 months, and median time to recurrence was 12 months. Overall, the numbers of liver recurrence and pulmonary recurrence were 94 (7.9%) and 70 (5.9%), respectively. Higher N status was significantly associated with increased risk of pulmonary recurrence (N0 vs. N1a, p = 0.02; N0 vs. N1b, p < 0.01; N0 vs. N2a, p < 0.01; N0 vs. N2b, p < 0.01) and worse pulmonary recurrence-free survival, but not other recurrences. In Non-LNM patients, on the other hand, advanced T status was associated with increased risk of pulmonary recurrence. The regional LNM was strongly associated with pulmonary metastasis as the first recurrence site following stage I-III CRC resection.

Persistent Circulating Tumor Cells at 1 Year After Oncologic Resection Predict Late Recurrence in Pancreatic Cancer

OBJECTIVE

The aim of the study was to assess the association between persistent circulating tumor cells (CTCs) and subsequent recurrence in patients who were clinically recurrence free ~12 months postoperatively.

BACKGROUND

Circulating tumor cells have been proposed as biomarkers to predict survival in pancreatic cancer. Some patients demonstrate persistent CTCs postoperatively, which could represent minimal residual disease.

METHODS

Patients from previously published prospective circulating tumor cell in pancreatic cancer trial without clinical evidence of recurrence 12 months postoperatively and CTC testing performed 9 to 15 months postoperatively were included. The presence of epithelial and transitional CTCs (trCTCs) was evaluated as predictor of recurrence. Kaplan-Meier curve, log-rank test, and Cox model were used for survival analysis.

RESULTS

Thirty-three of 129 eligible patients (circulating tumor cell in pancreatic cancer trial) were included. The trCTC-positive and negative patients were well balanced in clinicopathologic features. Patients with trCTCs had a recurrence rate per-person-month of 10.3% compared with 3.1% in trCTCs-negative patients with a median time to recurrence of 3.9 versus 27.1 months, respectively. On multivariable analysis, trCTCs positivity was associated with higher risk of late recurrence (hazard ratio: 4.7, 95% CI, 1.2-18.3, P =0.024). Fourteen (42.4%) patients recurred during the second postoperative year. One-year postoperative trCTCs positivity was associated with a higher rate of recurrence during the second year (odds ratio:13.1, 95% CI, 1.6-1953.4, P =0.028, area under curve=0.72). Integrating clinicopathologic features with trCTCs increased the area under curve to 0.80. A majority of trCTCs-positive patients (N=5, 62.5%) had multisite recurrence, followed by local-only (N=2, 25.0%) and liver-only (N=1, 12.5%) recurrence. This was in striking contrast to trCTCs-negative patients, where a majority (N=6, 66.7%) had a local-only recurrence, followed by liver-only (N=2, 22.2%) and multisite (N=1, 11.1%) recurrence.

CONCLUSIONS

In patients deemed to be clinically disease-free 12 months postoperatively, trCTCs positivity is associated with higher rates of subsequent recurrence with distinct patterns of recurrence. CTCs could be used a putative biomarker to guide patient prognostication and management in pancreatic cancer.

A guide for managing patients with stage I NSCLC: deciding between lobectomy, segmentectomy, wedge, SBRT and ablation-part 2: systematic review of evidence regarding resection extent in generally healthy patients

Background

Clinical decision-making for patients with stage I lung cancer is complex. It involves multiple options (lobectomy, segmentectomy, wedge, stereotactic body radiotherapy, thermal ablation), weighing multiple outcomes (e.g., short-, intermediate-, long-term) and multiple aspects of each (e.g., magnitude of a difference, the degree of confidence in the evidence, and the applicability to the patient and setting at hand). A structure is needed to summarize the relevant evidence for an individual patient and to identify which outcomes have the greatest impact on the decision-making.

Methods

A PubMed systematic review from 2000-2021 of outcomes after lobectomy, segmentectomy and wedge resection in generally healthy patients is the focus of this paper. Evidence was abstracted from randomized trials and non-randomized comparisons with at least some adjustment for confounders. The analysis involved careful assessment, including characteristics of patients, settings, residual confounding etc. to expose degrees of uncertainty and applicability to individual patients. Evidence is summarized that provides an at-a-glance overall impression as well as the ability to delve into layers of details of the patients, settings and treatments involved.

Results

In healthy patients there is no short-term benefit to sublobar resection vs. lobectomy in randomized and non-randomized comparisons. A detriment in long-term outcomes is demonstrated by adjusted non-randomized comparisons, more marked for wedge than segmentectomy. Quality-of-life data is confounded by the use of video-assisted approaches; evidence suggests the approach has more impact than the resection extent. Differences in pulmonary function tests by resection extent are not clinically meaningful in healthy patients, especially for multi-segmentectomy vs. lobectomy. The margin distance is associated with the risk of recurrence.

Conclusions

A systematic, comprehensive summary of evidence regarding resection extent in healthy patients with attention to aspects of applicability, uncertainty and effect modifiers provides a foundation on which to build a framework for individualized clinical decision-making.

Scientific Practice in Modeling Diseases: Stances from Cancer Research and Neuropsychiatry

In the last few decades, philosophy of science has increasingly focused on multilevel models and causal mechanistic explanations to account for complex biological phenomena. On the one hand, biological and biomedical works make extensive use of mechanistic concepts; on the other hand, philosophers have analyzed an increasing range of examples taken from different domains in the life sciences to test-support or criticize-the adequacy of mechanistic accounts. The article highlights some challenges in the elaboration of mechanistic explanations with a focus on cancer research and neuropsychiatry. It jointly considers fields, which are usually dealt with separately, and keeps a close eye on scientific practice. The article has a twofold aim. First, it shows that identification of the explananda is a key issue when looking at dynamic processes and their implications in medical research and clinical practice. Second, it discusses the relevance of organizational accounts of mechanisms, and questions whether thorough self-sustaining mechanistic explanations can actually be provided when addressing cancer and psychiatric diseases. While acknowledging the merits of the wide ongoing debate on mechanistic models, the article challenges the mechanistic approach to explanation by discussing, in particular, explanatory and conceptual terms in the light of stances from medical cases.

miR-30a/SOX4 Double Negative Feedback Loop is modulated by Disulfiram and regulates EMT and Stem Cell-like properties in Breast Cancer

Background: Both epithelial-to-mesenchymal transition (EMT) and cancer stem cells play important roles in development and progression of breast cancer. MicroRNA (miR)-30 family members have been reported to be associated with the regulation of EMT and stem cell phenotypes, however, the underlying molecular mechanisms are not well understood.

Methods: miR-30a stable transfectants of breast cancer cell lines were created using a lentiviral system. Bioinformatics analysis was performed to explore miR-30a target genes and SOX4 was selected and identified by dual luciferase reporter assay. The effects of miR-30a and target gene SOX4 on EMT and CSC phenotypes in breast cancer were explored in vitro and in vivo.

Results: Overexpression of miR-30a in breast cancer cells inhibited EMT and CSC phenotypes by targeting SOX4. Luciferase reporter assay confirmed that miR-30a directly targeted 3'UTR of SOX4, and formed a double-negative feedback loop with SOX4. Functional experiments demonstrated that knockdown of SOX4 suppressed EMT and CSC phenotypes of breast cancer cells through TGF-β/SMAD pathway, which was consistent with the inhibitory effects by overexpression of miR-30a. Additionally, we found disulfiram can upregulate miR-30a expression, and high miR-30a expression was associated with a good prognosis in breast cancer patients through TCGA database.

Conclusion: Our findings suggest a novel double-negative loop between miR-30a and SOX4 mediated regulation of EMT and CSC features in breast cancer through TGF-β/SMAD pathway, highlighting a novel therapeutic target for breast cancer.

Heterogeneity of Colorectal Cancer Progression: Molecular Gas and Brakes

The review begins with molecular genetics, which hit the field unveiling the involvement of oncogenes and tumor suppressor genes in the pathogenesis of colorectal cancer (CRC) and uncovering genetic predispositions. Then the notion of molecular phenotypes with different clinical behaviors was introduced and translated in the clinical arena, paving the way to next-generation sequencing that captured previously unrecognized heterogeneity. Among other molecular regulators of CRC progression, the extent of host immune response within the tumor micro-environment has a critical position. Translational sciences deeply investigated the field, accelerating the pace toward clinical transition, due to its strong association with outcomes. While the perturbation of gut homeostasis occurring in inflammatory bowel diseases can fuel carcinogenesis, micronutrients like vitamin D and calcium can act as brakes, and we discuss underlying molecular mechanisms. Among the components of gut microbiota, Fusobacterium nucleatum is over-represented in CRC, and may worsen patient outcome. However, any translational knowledge tracing the multifaceted evolution of CRC should be interpreted according to the prognostic and predictive frame of the TNM-staging system in a perspective of clinical actionability. Eventually, we examine challenges and promises of pharmacological interventions aimed to restrain disease progression at different disease stages.

Characterization of evolution trajectory and immune profiling of brain metastasis in lung adenocarcinoma

Characterizing the evolutionary trajectory and immune profiling of brain metastasis (BM) may provide insights in the development of novel therapeutic strategies. Here, we performed whole-exome sequencing and multiplex immunofluorescence (MIF) of 40 samples from 12 lung adenocarcinoma (LUAD) patients with BM and compared to their paired primary tumors. We observed significantly higher intertumor heterogeneity between paired primary tumors and BMs, with only a median of 8.3% of genetic mutations identified as shared. Phylogenetic analysis revealed that BM-competent clones genetically diverged from their primary tumors at relatively early stage, suggesting that the parallel progression model is dominant. In cases with synchronous lymph node metastasis (LNM), phylogenetic analysis suggested that BM is a later event than LNM. MIF analysis found that BMs exhibited significantly lower CD8+ T cell infiltration (P = 0.048), and elevated CD4+Foxp3+ T cell infiltration (P = 0.036) and PD-1 expression (P = 0.047) in comparison to the matched primary tumors, indicating an immunosuppressive microenvironment in BMs. The current study revealed the discrepancy of mutational landscape as well as tumor immune microenvironment between BM and its primary tumor - such findings shall help us better understand the unique biological features of BM and develop innovative strategies accordingly for our patients with LUAD.

Are there imaging characteristics that can distinguish separate primary lung carcinomas from intrapulmonary metastases using next-generation sequencing as a gold standard?

OBJECTIVES

Distinguishing separate primary lung carcinomas (SPLCs) from intrapulmonary metastases (IPMs) in non-small cell lung cancer (NSCLC) patients is a challenging dilemma in clinical practice. Next-generation sequencing (NGS) was recently shown to represent a robust molecular method for clonal discrimination in this setting. In this study, using clonal relationships established by comprehensive NGS as the ground truth, we investigated whether NSCLC patients with SPLCs versus IPMs exhibit distinct imaging characteristics.

MATERIAL AND METHODS

This retrospective study included patients who underwent pre-treatment computed tomography (CT) and/or positron emission tomography/CT (PET/CT) imaging followed by surgical resection for >1 NSCLC. Nodular, parenchymal, pleural, and ancillary CT features, as well as maximum standardized uptake values (SUVs) on PET/CT were recorded. Rao-Scott chi-square, Wilcoxon rank-sum, and Fisher's exact tests were used in patient- and lesion-level comparisons.

RESULTS

This study included 60 patients (median age = 69 years, 68 % female) with 127 individual tumors comprising 51 SPLC vs 23 IPM tumor pairs based on NGS profiling. SPLCs were associated with subsolid consistency (P = 0.005) and spiculated contours (P <  0.001), while IPMs were associated with greater difference of size between lesions (P = 0.017) or pure solid consistency of the smaller lesion (P = 0.011). Lymph node involvement was more frequent in IPMs than SPLCs (P = 0.036). SUV measurements were not useful for differentiation (P > 0.05).

CONCLUSION

Selected preoperative CT features are distributed differentially in SPLCs and IPMs, suggesting that imaging may have a role in distinguishing clonal relationships of tumors in patients with >1 NSCLC.

International validation of a risk prediction algorithm for patients with malignant colorectal polyps

AIM

The optimal management strategy for patients with endoscopically resected malignant colorectal polyps (MCP) has yet to be defined. The aim of this study was to validate a published decision-making tool, termed the Scottish Polyp Cancer Study (SPOCS) algorithm, on a large international population.

METHODS

The SPOCS algorithm allocates patients to risk groups based on just two variables: the polyp resection margin and the presence of lymphovascular invasion (LVI). The risk groups are termed low (clear margin, LVI absent), medium (clear margin, LVI present) or high (involved/non-assessable margin). The International Polyp Cancer Collaborative was formed to validate the algorithm on data from Australia, Denmark, UK and New Zealand.

RESULTS

In total, 1423 patients were included in the final dataset. 680/1423 (47.8%) underwent surgical resection and 108/680 (15.9%) had residual disease (luminal disease 8.8%, lymph node metastases 8.8%). The SPOCS algorithm classified 602 patients as low risk (in which 1.5% had residual disease), 198 patients as medium risk (in which 7.1% had residual disease) and 484 as high risk (in which 14.5% had residual disease) (P < 0.001, χ² test). Receiver operating characteristic curve analysis demonstrated good accuracy of the algorithm in predicting residual disease (area under the curve 0.732, 95% CI 0.687-0.778, P < 0.001). When patients were designated as low risk, the negative predictive value was 98.5%.

CONCLUSION

The SPOCS algorithm can be used to predict the risk of residual disease in patients with endoscopically resected MCPs. Surgery can be safely avoided in patients who have a clear margin of excision and no evidence of LVI.

PKM2 in Canine Mammary Tumors: Parallels to Human Breast Cancer

PKM2 is a pyruvate kinase isoform that is the final and rate-limiting step in aerobic glycolysis in tumor cells. Increased expression of PKM2 has been detected in human cancers. The present study examined the expression of PKM2 in canine mammary tumors and assessed its prognostic significance. Paraffin sections of 5 adenomas, 67 carcinomas, and 5 samples of nonneoplastic hyperplasia from 77 dogs, aged 8 to 18 y, were evaluated. Significantly higher levels of PKM2 were detected among the carcinomas compared with all other tissues examined. The level of PKM2 expression in carcinoma tissue correlated positively with the tumor grade. These findings suggest that PKM2 may have a similar role in canine mammary tumors to its role in human breast cancer. As such, canine mammary tumors may be useful models for studies focused on the progression of human neoplastic disease.

Mapping the spreading routes of lymphatic metastases in human colorectal cancer

Lymphatic metastases are closely associated with tumor relapse and reduced survival in colorectal cancer (CRC). How tumor cells disseminate within the lymphatic network remains largely unknown. Here, we analyze the subclonal structure of 94 tumor samples, covering the primary tumors, lymph node metastases (LNMs), and liver metastases from 10 CRC patients. We portray a high-resolution lymphatic metastatic map for CRC by dividing LNMs into paracolic, intermediate, and central subgroups. Among the 61 metastatic routes identified, 38 (62.3%) are initiated from the primary tumors, 22 (36.1%) from LNMs, and 1 from liver metastasis (1.6%). In 5 patients, we find 6 LNMs that reseed 2 or more LNMs. We summarize 3 diverse modes of metastasis in CRC and show that skip spreading of tumor cells within the lymphatic network is common. Our study sheds light on the complicated metastatic pattern in CRC and has great clinical implications.

Lymphatic metastases are closely associated with tumor relapse and reduced survival in colorectal cancer (CRC). Here, the authors analysed the primary tumours, lymph node metastasis and liver metastasis of ten CRC patients and reveal co-existence of diverse modes of metastasis in the same patient.

The Role of Cyclooxygenase-2 in Colorectal Cancer

Colorectal cancer is the third common cancer in this world, accounting for more than 1 million cases each year. However, detailed etiology and mechanism of colorectal cancer have not been fully understood. For example, cyclooxygenase-2 (COX-2) and its product prostaglandin E₂ (PGE₂) have been closely linked to its occurrence, progression and prognosis. However, the mechanisms on how COX-2 and PGE₂-mediate the pathogenesis of colorectal cancer are obscure. In this review, we have summarized recent advances in studies of pathogenesis and control in colorectal cancer to assist further advances in the research for the cure of the cancer. In addition, the knowledge gained may also guide the audiences for reduction of the risk and control of this deadly disease.

COX-2 Signaling in the Tumor Microenvironment

Tumorigenesis is a multistep, complicated process, and many studies have been completed over the last few decades to elucidate this process. Increasingly, many studies have shifted focus toward the critical role of the tumor microenvironment (TME), which consists of cellular players, cell-cell communications, and extracellular matrix (ECM). In the TME, cyclooxygenase-2 (COX-2) has been found to be a key molecule mediating the microenvironment changes. COX-2 is an inducible form of the enzyme that converts arachidonic acid into the signal transduction molecules (thromboxanes and prostaglandins). COX-2 is frequently expressed in many types of cancers and has been closely linked to its occurrence, progression, and prognosis. For example, COX-2 has been shown to (1) regulate tumor cell growth, (2) promote tissue invasion and metastasis, (3) inhibit apoptosis, (4) suppress antitumor immunity, and (5) promote sustainable angiogenesis. In this chapter, we summarize recent advances of studies that have evaluated COX-2 signaling in TME.

Analysis of prognostic factors and clinical outcomes in uterine cervical carcinoma with isolated para-aortic lymph node recurrence

To evaluate clinical outcomes and to identify prognostic factors in isolated para-aortic lymph node (PALN) recurrence, we retrospectively reviewed 65 patients who developed PALN recurrence as the first site of tumor progression from a total of 1521 patients who were treated with curative pelvic radiation therapy (RT) for uterine cervical carcinoma between May 1993 and January 2017. Forty-five of the 65 patients received salvage therapy. The median salvage PALN radiation dose was 54 Gy (range: 18 to 62 Gy). Prognostic factors for overall survival (OS) and distant metastases (DMs) were analyzed with univariate and multivariate Cox regression. The median follow-up period for surviving patients was 61 months (4-202 months). The median OS was 27.7 months (0.3-202 months). The highest level of PALN metastases at or above the L1 spinal level (hazard ratio [HR] 9.88, 95% confidence interval [CI] 3.44-28.38, P<0.001) and the presence of leg edema and/or back pain at recurrence (HR 3.25, 95% CI 1.57-6.75, P=0.002) were significantly associated with worse OS. A significantly higher incidence of DMs (HR 5.97, 95% CI 2.05-17.35, P=0.001) was found in the patients with a high level (≥L1) of PALN metastases. Salvage RT (HR 0.35, 95% CI 0.17-0.71, P=0.004) and restaging with positron emission tomography/computed tomography (PET/CT) (HR 0.2, 95% CI 0.04-0.93, P=0.039) were independent predictors of a better OS. In conclusion, a high level (≥L1) of PALN metastases predicts poor survival and a high rate of DMs. Periodic surveillance for early detection and restaging by PET/CT imaging to identify the optimal treatment at recurrence is recommended.

Rapid evolution and biogeographic spread in a colorectal cancer

How and when tumoral clones start spreading to surrounding and distant tissues is currently unclear. Here we leveraged a model-based evolutionary framework to investigate the demographic and biogeographic history of a colorectal cancer. Our analyses strongly support an early monoclonal metastatic colonization, followed by a rapid population expansion at both primary and secondary sites. Moreover, we infer a hematogenous metastatic spread under positive selection, plus the return of some tumoral cells from the liver back to the colon lymph nodes. This study illustrates how sophisticated techniques typical of organismal evolution can provide a detailed, quantitative picture of the complex tumoral dynamics over time and space.

The clonal origins of metastases and the timing of dissemination remains an open question for most cancer types. Using primary and metastatic samples taken from one colorectal cancer patient, Alves et al. use Bayesian phylogenetics to reconstruct the history of metastasis.

RFC3 induces epithelial‑mesenchymal transition in lung adenocarcinoma cells through the Wnt/β‑catenin pathway and possesses prognostic value in lung adenocarcinoma

Lung cancer is a malignant tumor responsible for the highest mortality rate in humans. The identification of novel functional genes is of great importance in the treatment of lung cancer. The reported roles of replication factor C subunit 3 (RFC3) in tumorigenesis are contradictory. The present study aimed to explore the role and mechanism of RFC3 in lung cancer cells. An immunohistochemical study of 165 lung cancer and adjacent tissues was conducted (123 lung adenocarcinoma tissues and 42 lung squamous cell carcinoma tissues). Kaplan-Meier analysis and Cox multivariate analysis were employed to explore the relationship between RFC3 and patient prognosis. In addition, the proliferation, cell cycle distribution and apoptosis of A549 and H1299 cells were determined by MTT assay and flow cytometry, respectively, following cell transfection to induce overexpression and knockdown of RFC3. A Boyden chamber assay and wound-healing assay were conducted to determine the invasive and migratory abilities of A549 and H1299 cells. Western blotting was used to analyze the effects of RFC3 overexpression and RFC3 small interfering RNA-induced knockdown, and to explore the potential mechanism and pathway underlying the effects of RFC3. Positive expression of RFC3 was detected in lung adenocarcinoma, and overexpression of RFC3 shortened the survival time of patients with lung adenocarcinoma. Furthermore, overexpression of RFC3 increased the invasion and migration of A549 cells, whereas knockdown of RFC3 significantly reduced the invasion and migration of H1299 cells. Ectopic expression of RFC3 induced epithelial-mesenchymal transition (EMT), as determined by downregulation of E-cadherin, and upregulation of N-cadherin, vimentin and Wnt signaling target genes, including c-MYC, Wnt1 and β-catenin, and the ratio of phosphorylated-glycogen synthase kinase 3 (GSK3)-β (Ser9)/GSK3-β. In conclusion, RFC3 may be considered a coactivator that promotes the Wnt/β-catenin signaling pathway, and induces EMT and metastasis in lung adenocarcinoma.

Epigenetic Regulation of Inflammatory Cytokine-Induced Epithelial-To-Mesenchymal Cell Transition and Cancer Stem Cell Generation

The neoplastic transformation of normal to metastatic cancer cells is a complex multistep process involving the progressive accumulation of interacting genetic and epigenetic changes that alter gene function and affect cell physiology and homeostasis. Epigenetic changes including DNA methylation, histone modifications and changes in noncoding RNA expression, and deregulation of epigenetic processes can alter gene expression during the multistep process of carcinogenesis. Cancer progression and metastasis through an ‘invasion–metastasis cascade’ involving an epithelial-to-mesenchymal cell transition (EMT), the generation of cancer stem cells (CSCs), invasion of adjacent tissues, and dissemination are fueled by inflammation, which is considered a hallmark of cancer. Chronic inflammation is generated by inflammatory cytokines secreted by the tumor and the tumor-associated cells within the tumor microenvironment. Inflammatory cytokine signaling initiates signaling pathways leading to the activation of master transcription factors (TFs) such as Smads, STAT3, and NF-κB. Moreover, the same inflammatory responses also activate EMT-inducing TF (EMT-TF) families such as Snail, Twist, and Zeb, and epigenetic regulators including DNA and histone modifying enzymes and micoRNAs, through complex interconnected positive and negative feedback loops to regulate EMT and CSC generation. Here, we review the molecular regulatory feedback loops and networks involved in inflammatory cytokine-induced EMT and CSC generation.

Fucoidan-coated coral-like Pt nanoparticles for computed tomography-guided highly enhanced synergistic anticancer effect against drug-resistant breast cancer cells

Chemotherapy, the most commonly applied cancer treatment, often causes unexpected failure due to multidrug resistance (MDR). To overcome MDR, we have designed a platform to realize a combinational synergistic effect of a natural bioactive product (fucoidan), anticancer small compound (doxorubicin), and photothermal nanocarrier (Pt nanoparticle) to treat drug-resistant breast cancer cells. Especially, fucoidan, a sulfated, polysaccharide-structured, therapeutic biopolymer, has been recently recognized as a potential anticancer compound; however, its cancer-inhibiting efficacy has been regarded as low owing to its insufficient level in serum following its conventional oral ingestion. To enhance its potency, fucoidan was applied as a biocompatible surfactant and surface-coating biopolymer in nanocarrier synthesis to manufacture coral-like, fucoidan-coated Pt nanoparticles with a rough surface morphology by a one-pot method. As a result, the biological-thermo-chemo trimodal combination treatment showed excellent therapeutic efficiency against the MDR breast cancer cell MCF-7 ADR both in vitro and in vivo, and the computed tomography contrast effect was also confirmed from the constituent element Pt. Beyond universal application in drug delivery and photothermal therapy, the present approach of applying a MDR modulating/anticancer natural product from nanoparticle synthesis to theranostics will contribute greatly to maximizing their potential through interdisciplinary convergence in the near future.

[An integral view of cancer (I). The study, classification and reprogramming of the tumoral microclimate]

The group of diseases that we call cancer share a biological structure formed by a complex ecosystem, with altered intercellular communication, information fields, development and tissue function. Beyond the genetic alterations of the tumor cell, the demonstration of an altered ecosystem, with interconnections at systemic levels, opens up a new perspective on cancer biology and behavior. Different tumor facets, such as morphology, classification, clinical aggressiveness, prognosis and response to treatment now appear under a comprehensive vision that offers a new horizon of study, research and clinical management. The Somatic Mutation Theory in cancer, in force for more than one hundred years, is now completed by the study of the tumor microenvironment, the extracellular matrix, the stromal cells, the immune response, the innervation, the nutrition, the mitochondria, the metabolism, the interstitial fluid, the mechanical and electromagnetic properties of the tissue and many other areas of emerging knowledge; thus opening the door to a reprogramming exercise of the tumor phenotype through the modification of the keys offered by this new paradigm. Its recognition makes it possible to go from considering the oncological process as a cellular problem to a supracellular alteration based on the disorganization of tissues, immersed in the relationships of the complex system of the living being.

Expression of zinc finger transcription factors (ZNF143 and ZNF281) in serous borderline ovarian tumors and low-grade ovarian cancers

Low-grade ovarian cancers represent up to 8% of all epithelial ovarian carcinomas (EOCs). Recent studies demonstrated that epithelial-mesenchymal transition (EMT) is crucial for the progression of EOCs. EMT plays a key role in cancer invasion, metastasis formation and chemotherapy resistance. An array of novel EMT transcription factors from the zinc finger protein family have been described recently, among them zinc finger protein 143 (ZNF143) and zinc finger protein 281 (ZNF281). The study included tissue specimens from 42 patients. Based on histopathological examination of surgical specimens, eight lesions were classified as serous borderline ovarian tumors (sBOTs) and 34 as low-grade EOCs. The proportions of the ovarian tumors that tested positively for ZNF143 and ZNF281 were 90 and 57%, respectively. No statistically significant differences were found in the expressions of ZNF143 and ZNF281 transcription factors in SBOTs and low-grade EOCs. Considering the expression patterns for ZNF143 and ZNF281 identified in this study, both sBOTs and low-grade EOCs might undergo a dynamic epithelial-mesenchymal interconversion. The lack of statistically significant differences in the expressions of the zinc finger proteins in sBOTs and low-grade serous EOCs might constitute an evidence for common origin of these two tumor types.

Mutation heterogeneity between primary gastric cancers and their matched lymph node metastases

BACKGROUND

The acquisition of an invasive phenotype by a tumor cell is a crucial step of malignant transformation. The underlying genetic mechanisms in gastric cancer (GC) are not well understood.

METHODS

We performed whole-exome sequencing of 15 pairs of primary GC and their matched lymph node (LN) metastases (10 primary GCs with single matched LNs and 5 primary GCs with three LNs per case, respectively). Somatic alterations including single nucleotide variations, short insertions/deletions including locus-level microsatellite instability and copy number alterations were identified and compared between the primary and metastatic LN genomes.

RESULTS

Mutation abundance was comparable between the primary GC and LN metastases, but the extent of mutation overlap or the mutation heterogeneity between primary and LN genomes varied substantially. Primary- or LN-specific mutations could be distinguished from common mutations in terms of mutation spectra and functional categories, suggesting that the mutation forces are not constant during gastric carcinogenesis. A spatial distribution revealed TP53 mutations as common mutations along with a number of region-specific mutations, such as primary-specific SMARCA4 and LN-specific CTNNB1 mutations. The subclonal architectures of common mutations were largely conserved between primary GC and LN metastatic genomes. The mutation-based phylogenetic analyses further showed that LN metastases may have arisen from homogeneous subclones of primary tumors.

CONCLUSIONS

The abundance and spatial distribution of mutations may provide clues on the evolutionary relationship between primary and matched LN genomes. Gene-level analyses further distinguished the early addicted cancer drivers such as TP53 mutations from late acquired region-specific mutations.

Multi-targeting chemoprevention of Chinese herb formula Yanghe Huayan decoction on experimentally induced mammary tumorigenesis

BACKGROUND

Development of safe and effective chemopreventive agents is a winning strategy in reducing the morbidity and mortality of breast cancer. The current study was to investigate the mechanism-based chemopreventive potential of a Chinese herb formula Yanghe Huayan (YHHY) Decoction on the classical 7,12-dimethylbenz(a)anthracene (DMBA) induced rat mammary carcinogenesis model.

METHODS

Female Sprague-Dawley rats at 42 days of age were orally administered with a human equivalent dose of YHHY Decoction at 0.02 ml/g (10 mg/ml) once daily, starting 1 wk. before and 4 wks following DMBA treatment. Mammary tumor occurrence was monitored every day. The length of time before palpable tumor is examined is defined as tumor-free survival time. High performance liquid chromatography (HPLC) analyses were adopted to identify major chemical compositions of the decoction. Following bioinformatics data mining and experimental analyses were performed to demonstrate the underlying mechanism of action.

RESULTS

DMBA animals receiving YHHY Decoction exhibited a significant delay (P = 0.014) and in some animals prevention (P = 0.046) of tumor occurrence without obvious toxicity. Oncogenic myc activation was significantly suppressed in the DMBA-induced rats by the YHHY treatment. Eight major chemical compositions of the decoction were identified and were shown to interfere with multiple tumorigenic pathways simultaneously in the mammary tumors, including inducing tumor apoptosis and up-regulating pro-apoptotic protein Bax and down-regulating anti-apoptotic protein Bcl-2; suppressing abnormal cell proliferation and the MAPK/ERK, PI3K/AKT signalings; blocking neo-angiogenesis and the VEGF/KDR signaling, and inhibiting oxidative stress in the mammary tumors.

CONCLUSION

The multi-components and multi-targeting properties of the YHHY Decoction support its use as a potent chemopreventive drug in breast cancer.

The Emerging Role of Estrogens in Thyroid Redox Homeostasis and Carcinogenesis

Reactive oxygen species (ROS) are the most critical class of free radicals or reactive metabolites produced by all living organisms. ROS regulate several cellular functions through redox-dependent mechanisms, including proliferation, differentiation, hormone synthesis, and stress defense response. However, ROS overproduction or lack of appropriate detoxification is harmful to cells and can be linked to the development of several diseases, such as cancer. Oxidative damage in cellular components, especially in DNA, can promote the malignant transformation that has already been described in thyroid tissue. In thyrocyte physiology, NADPH oxidase enzymes produce large amounts of ROS that are necessary for hormone biosynthesis and might contribute to the high spontaneous mutation rate found in this tissue. Thyroid cancer is the most common endocrine malignancy, and its incidence is significantly higher in women than in men. Several lines of evidence suggest the sex hormone estrogen as a risk factor for thyroid cancer development. Estrogen in turn, besides being a potent growth factor for both normal and tumor thyroid cells, regulates different mechanisms of ROS generation. Our group demonstrated that the thyroid gland of adult female rats exhibits higher hydrogen peroxide (H₂O₂) production and lower enzymatic antioxidant defense in comparison with male glands. In this review, we discuss the possible involvement of thyroid redox homeostasis and estrogen in the development of thyroid carcinogenesis.

Molecular Classification of Lymph Node Metastases Subtypes Predict for Survival in Head and Neck Cancer

PURPOSE

In advanced stage head and neck squamous cell cancers (HNSCC), approximately half of the patients with lymph node metastases (LNM) are not cured. Given the heterogeneous outcomes in these patients, we profiled the expression patterns of LNMs to identify the biological factors associated with patient outcomes.Experimental Design: We performed mRNAseq and miRNAseq on 72 LNMs and 29 matched primary tumors from 34 patients with HNSCC. Clustering identified molecular subtypes in LNMs and in primary tumors. Prediction Analysis of Microarrays algorithm identified a 73-gene classifier that distinguished LNM subtypes. Gene-set enrichment analysis identified pathways upregulated in LNM subtypes.

RESULTS

Integrative clustering identified three distinct LNM subtypes: (i) an immune subtype (Group 1), (ii) an invasive subtype (Group 2), and (iii) a metabolic/proliferative subtype (Group 3). Group 2 subtype was associated with significantly worse locoregional control and survival. LNM-specific subtypes were not observed in matched primary tumor specimens. In HNSCCs, breast cancers, and melanomas, a 73-gene classifier identified similar Group 2 LNM subtypes that were associated with worse disease control and survival only when applied to lymph node sites, but not when applied to other primary tumors or metastatic sites. Similarly, previously proposed prognostic classifiers better distinguished patients with worse outcomes when applied to the transcriptional profiles of LNMs, but not the profiles of primary tumors.

CONCLUSIONS

The transcriptional profiles of LNMs better predict outcomes than transcriptional profiles of primary tumors. The LNMs display site-specific subtypes associated with worse disease control and survival across multiple cancer types.

Bioenergetics of life, disease and death phenomena

In this article, some new aspects of unified cell bioenergetics are presented. From the perspective of unified cell bioenergetics certain subsequent stages of cancer development, from initiation stage, through transformation to metastasis, are analyzed. Here we show that after transformation, cancer cells are permanently exposed to reactive oxygen species, that causes continual random DNA mutations and as a result genome and chromosomal destabilizations. The modern cancer attractor hypothesis has been extended in explaining cancer development. Discussion is conducted in light of current cancerogenesis research, including bioenergetic cancer initiation, the somatic mutation theory and the tissue organization field theory. In the article reasons complicating the discovery of patterns of cancer genome changes and cancer evolution are presented. In addition certain cancer therapeutic aspects are given attention to.

Salidroside inhibits the proliferation and migration of gastric cancer cells via suppression of Src‑associated signaling pathway activation and heat shock protein 70 expression

Salidroside, an active ingredient extracted from the Rhodiola rosea plant, has potential anti-tumor effects. However, the effects of salidroside on gastric cancer cell proliferation and migration remain unclear. In the present study, the inhibitory effects of salidroside on gastric cancer cell proliferation, migration and invasion and the molecular mechanisms underlying these effects were investigated. The human gastric cancer cell line, BGC-823, was treated with different concentrations of salidroside (200, 400 and 600 µg/ml). Cell proliferation was determined with Cell Counting Kit-8 and colony formation assays, and the migration and invasion of cells was detected by a wound healing and Transwell assay, respectively. Western blotting was performed to detect the levels of N-cadherin, E-cadherin and heat shock protein (HSP)70. In addition, the phosphorylation of proto-oncogene tyrosine-protein kinase Src (Src), protein kinase B (Akt), mitogen activated protein kinase 1 (ERK), signal transducer and activator of transcription (STAT)3 and focal adhesion kinase 1 (FAK) was examined by western blotting. The levels of matrix metalloproteinase (MMP)-2 and MMP-9 were determined by enzyme-linked immunosorbent assay kits. Levels of reactive oxygen species (ROS) in cells were measured by a fluorescence plate reader with dichloro-dihydro-fluorescein diacetate. The results indicated that salidroside significantly suppressed cell proliferation and colony formation, inhibited cell migration and invasion, increased E-cadherin expression and decreased N-cadherin, MMP-2 and MMP-9 expression. Furthermore, salidroside suppressed ROS production and subsequently reduced the phosphorylation of Src, Akt, ERK and FAK. Salidroside also inhibited HSP70 expression, and HSP70 overexpression reversed the inhibitory effects of salidroside on BGC-823 cell proliferation, migration and invasion. In conclusion, the present study revealed that salidroside inhibited the proliferation, migration and invasion of BGC-823 cells by downregulating ROS-mediated Src-associated signaling pathway activation and HSP70 expression.

Phylogenetic Quantification of Intratumor Heterogeneity

As sequencing efforts continue to reveal the extent of the intratumor heterogeneity (ITH) present in human cancers, the importance of evolutionary studies attempting to trace its etiology has increased. Sequencing multiple samples or tumor regions from the same patient has become affordable and is an effective way of tracing these evolutionary pathways, understanding selection, and detecting clonal expansions in ways impractical with single samples alone. In this article, we discuss and show the benefits of such multisample studies. We describe how multiple samples can guide tree inference through accurate phasing of germline variants and copy-number profiles. We show their relevance in detecting clonal expansions and deriving summary statistics quantifying the overall degree of ITH, and discuss how the relationship of metastatic clades might give us insight into the dominant mode of cancer progression. We further outline how multisample studies might help us better understand selective processes acting on cancer genomes and help to detect neutral evolution and mutator phenotypes.

ED-B fibronectin expression is a marker of epithelial-mesenchymal transition in translational oncology

Fibronectin is a component of the extracellular matrix that links collagen fibers to integrins on the cell's surface. The splicing isoforms, containing the ED-B domain, are not expressed in adult tissues but only in tumor stroma or during embryonic development. Fibroblasts and endothelial cells express ED-B fibronectin during angiogenesis. Also cancer cells can synthetize ED-B fibronectin, but its function in tumor growth needs to be further elucidated.

We evaluated the expression of ED-B fibronectin in prostate cancer cell lines: PC3 and DU145. Using TGF-β, we induced epithelial to mesenchymal transition in culture and observed an increase of ED-B fibronectin expression. Thereafter, we evaluated the expression of ED-B fibronectin in multipotent mesangiogenic progenitor cells, and in mesenchymal stromal cells. The expression of ED-B fibronectin was much higher in mesenchymal than prostate cancer cells even after the epithelial to mesenchymal transition.

Epithelial to mesenchymal transition is a key step for tumor progression contributing to the metastatic spread. Therefore, circulating cancer cells could seed into the metastatic niche taking advantage from the ED-B fibronectin that secrete their own.

LTBP3 promotes early metastatic events during cancer cell dissemination

Latent Transforming Growth Factor β (TGFβ) Binding Proteins (LTBPs) are important for the secretion, activation and function of mature TGFβ, especially so in cancer cell physiology. However, specific roles of the LTBPs remain understudied in the context of the primary tumor microenvironment. Herein, we investigated the role of LTBP-3 in the distinct processes involved in cancer metastasis. By using three human tumor cell lines of different tissue origin (epidermoid HEp-3 and prostate PC-3 carcinomas and HT-1080 fibrosarcoma) and several metastasis models conducted in both mammalian and avian settings, we show that LTBP-3 is involved in the early dissemination of primary cancer cells, namely in the intravasation step of the metastatic cascade. Knockdown of LTBP-3 in all tested cell lines led to significant inhibition of tumor cell intravasation, but did not affect primary tumor growth. LTBP-3 was dispensable in the late steps of carcinoma cell metastasis that follow tumor cell intravasation, including vascular arrest, extravasation and tissue colonization. However, LTBP-3 depletion diminished the angiogenesis-inducing potential of HEp-3 cells in vivo, which was restorable by exogenous delivery of LTBP-3 protein. A similar compensatory approach rescued the dampened intravasation of LTBP-3-deficient HEp-3 cells, suggesting that LTBP-3 regulates the induction of the intravasation-supporting angiogenic vasculature within developing primary tumors. Using our recently developed microtumor model, we confirmed that LTBP-3 loss resulted in the development of intratumoral vessels with an abnormal microarchitecture incompatible with efficient intravasation of HEp-3 carcinoma cells. Collectively, these findings demonstrate that LTBP-3 represents a novel oncotarget that has distinctive functions in the regulation of angiogenesis-dependent tumor cell intravasation, a critical process during early cancer dissemination. Our experimental data are also consistent with the survival prognostic value of LTBP3 expression in early stage head and neck squamous cell carcinomas, further indicating a specific role for LTBP-3 in cancer progression towards metastatic disease.

Identifying biomarkers of breast cancer micrometastatic disease in bone marrow using a patient-derived xenograft mouse model

BACKGROUND

Disseminated tumor cells (DTCs) found in the bone marrow (BM) of patients with breast cancer portend a poor prognosis and are thought to be intermediaries in the metastatic process. To assess the clinical relevance of a mouse model for identifying possible prognostic and predictive biomarkers of these cells, we have employed patient-derived xenografts (PDX) for propagating and molecularly profiling human DTCs.

METHODS

Previously developed mouse xenografts from five breast cancer patients were further passaged by implantation into NOD/SCID mouse mammary fat pads. BM was collected from long bones at early, serial passages and analyzed for human-specific gene expression by qRT-PCR as a surrogate biomarker for the detection of DTCs. Microarray-based gene expression analyses were performed to compare expression profiles between primary xenografts, solid metastasis, and populations of BM DTCs. Differential patterns of gene expression were then compared to previously generated microarray data from primary human BM aspirates from patients with breast cancer and healthy volunteers.

RESULTS

Human-specific gene expression of SNAI1, GSC, FOXC2, KRT19, and STAM2, presumably originating from DTCs, was detected in the BM of all xenograft mice that also developed metastatic tumors. Human-specific gene expression was undetectable in the BM of those xenograft lines with no evidence of distant metastases and in non-transplanted control mice. Comparative gene expression analysis of BM DTCs versus the primary tumor of one mouse line identified multiple gene transcripts associated with epithelial-mesenchymal transition, aggressive clinical phenotype, and metastatic disease development. Sixteen of the PDX BM associated genes also demonstrated a statistically significant difference in expression in the BM of healthy volunteers versus the BM of breast cancer patients with distant metastatic disease.

CONCLUSION

Unique and reproducible patterns of differential gene expression can be identified that presumably originate from BM DTCs in mouse PDX lines. Several of these identified genes are also detected in the BM of patients with breast cancer who develop early metastases, which suggests that they may be clinically relevant biomarkers. The PDX model may also provide a clinically relevant system for analyzing and targeting these intermediaries of metastases.

Cancer and intercellular cooperation

The major transitions approach in evolutionary biology has shown that the intercellular cooperation that characterizes multicellular organisms would never have emerged without some kind of multilevel selection. Relying on this view, the Evolutionary Somatic view of cancer considers cancer as a breakdown of intercellular cooperation and as a loss of the balance between selection processes that take place at different levels of organization (particularly single cell and individual organism). This seems an elegant unifying framework for healthy organism, carcinogenesis, tumour proliferation, metastasis and other phenomena such as ageing. However, the gene-centric version of Darwinian evolution, which is often adopted in cancer research, runs into empirical problems: proto-tumoural and tumoural features in precancerous cells that would undergo 'natural selection' have proved hard to demonstrate; cells are radically context-dependent, and some stages of cancer are poorly related to genetic change. Recent perspectives propose that breakdown of intercellular cooperation could depend on 'fields' and other higher-level phenomena, and could be even mutations independent. Indeed, the field would be the context, allowing (or preventing) genetic mutations to undergo an intra-organism process analogous to natural selection. The complexities surrounding somatic evolution call for integration between multiple incomplete frameworks for interpreting intercellular cooperation and its pathologies.

Origins of lymphatic and distant metastases in human colorectal cancer

The spread of cancer cells from primary tumors to regional lymph nodes is often associated with reduced survival. One prevailing model to explain this association posits that fatal, distant metastases are seeded by lymph node metastases. This view provides a mechanistic basis for the TNM staging system and is the rationale for surgical resection of tumor-draining lymph nodes. Here we examine the evolutionary relationship between primary tumor, lymph node, and distant metastases in human colorectal cancer. Studying 213 archival biopsy samples from 17 patients, we used somatic variants in hypermutable DNA regions to reconstruct high-confidence phylogenetic trees. We found that in 65% of cases, lymphatic and distant metastases arose from independent subclones in the primary tumor, whereas in 35% of cases they shared common subclonal origin. Therefore, two different lineage relationships between lymphatic and distant metastases exist in colorectal cancer.

The role of metastasis-associated in colon cancer 1 (MACC1) in endometrial carcinoma tumorigenesis and progression

Metastasis-associated in colon cancer-1 (MACC1), has recently been identified as a key regulator in the progression of many cancers. However, its role in endometrial carcinoma (EC) remains unknown. MACC1 expression was determined in EC and normal endometrial tissues by immunohistochemistry. EC cell phenotypes and related molecules were examined after MACC1 downregulation by Small interfering RNA (siRNA) or microRNA (miRNA) transfection. We found that MACC1 was highly expressed in EC tissues than normal samples, and was significantly different in FIGO staging (I and II vs. III and IV), the depth of myometrial infiltration (<1/2 vs. ≥1/2), lymph nodes metastasis (negative vs. positive), besides, MACC1 overexpression was correlated with lower cumulative and relapse-free survival rate. MACC1 downregulation by siRNA transfection significantly induced G1 phrase arrest, suppressed EC cell proliferation, migration, and invasion. In addition, MACC1 downregulation also reduced expression of Cyclin D1 and Cyclin-dependent Kinase 2 (CDK2), N-cadherin (N-Ca), α-SMA, matrix metalloproteinase 2 (MMP2), and MMP9, but increased expression of E-cadherin (E-Ca). Bioinformatic predictions and dual-luciferase reporter assays indicate that MACC1 is a possible target of miR-23b. MiR-23b overexpression reduced MACC1 expression in vitro and induced G1 phrase arrest, suppressed cell proliferation, migration, and invasion. MiR-23b transfection also reduced Cyclin D1 and CDK2, N-Ca, α-SMA, MMP2, MMP9 expression, but increased E-Ca expression. Furthermore, the nude mouse xenograft assay showed that miR-23b overexpression suppressed tumour growth through downregulating MACC1 expression. Taken together, our results demonstrate for the first time that MACC1 may be a new and important diagnosis and therapeutic target of endometrial carcinoma.

Hypoxia-induced epithelial-mesenchymal transition is regulated by phosphorylation of GSK3-β via PI3 K/Akt signaling in oral squamous cell carcinoma

OBJECTIVE

Epithelial-mesenchymal transition (EMT) plays an important role in cancer invasion and metastasis induced by hypoxia. Here, we examined whether phosphorylation of GSK3-β via phosphoinositide 3-kinase (PI3 K)/Akt signaling is involved in enhancing the hypoxia-induced EMT in oral squamous cell carcinoma (OSCC).

STUDY DESIGN

Experiments were performed in OSCC cell lines (HSC-2, HSC-3, HSC-4, SAS, and HO-1-U-1) under normoxic or hypoxic conditions. The EMT was assessed by Matrigel invasion assays and wound healing assays. OSCC cell lines (HSC-2 and HSC-4) overexpressing hypoxia-inducible factor (HIF)-1α were established to examine the effects of HIF-1α on EMT-related factors. Immunohistochemical staining was performed to examine phosphorylation of GSK3-β in 33 cases of tongue squamous cell carcinoma.

RESULTS

Under hypoxic conditions, OSCC cell lines exhibited HIF-1α expression and showed evidence of the EMT. In cells overexpressing HIF-1α, the levels of phospho-Akt and phospho-GSK3-β were increased, resulting in induction of the EMT. Inhibition of GSK3-β phosphorylation suppressed these effects. Moreover, the intensity of pGSK3-β staining was significantly increased with cN stage and cTNM stage in patients with tongue squamous cell carcinoma.

CONCLUSIONS

Our data showed that the hypoxia-induced EMT in OSCC was enhanced by GSK3-β phosphorylation, suggesting that GSK3-β may be important in the invasion and metastasis of OSCC.

Tumor progression, metastasis, and modulators of epithelial-mesenchymal transition in endometrioid endometrial carcinoma: an update

Endometrioid endometrial carcinoma (EEC), also known as type 1 endometrial cancer (EC), accounts for over 70-80% of all cases that are usually associated with estrogen stimulation and often develops in a background of atypical endometrial hyperplasia. The increased incidence of EC is mainly confined to this type of cancer. Most EEC patients present at an early stage and generally have a favorable prognosis; however, up to 30% of EEC present as high risk tumors, which have invaded deep into the myometrium at diagnosis and progressively lead to local or extra pelvic metastasis. The poor survival of advanced EC is related to the lack of effective therapies, which can be attributed to poor understanding of the molecular mechanisms underlying the progression of disease toward invasion and metastasis. Multiple lines of evidence illustrate that epithelial-mesenchymal transition (EMT)-like events are central to tumor progression and malignant transformation, endowing the incipient cancer cell with invasive and metastatic properties. The aim of this review is to summarize the current knowledge on molecular events associated with EMT in progression, invasion, and metastasis of EEC. Further, the role of epigenetic modifications and microRNA regulation, tumor microenvironment, and microcystic elongated and fragmented glands like invasion pattern have been discussed. We believe this article may perhaps stimulate further research in this field that may aid in identifying high risk patients within this clinically challenging patient group and also lead to the recognition of novel targets for the prevention of metastasis - the most fatal consequence of endometrial carcinogenesis.

Krüppel-like factor 17, a novel tumor suppressor: its low expression is involved in cancer metastasis

Krüppel-like factor (KLF) family is highly conserved zinc finger transcription factors that regulate cell proliferation, differentiation, apoptosis, and migration. KLF17 is a member of the KLF family. Recent studies have demonstrated that KLF17 low expression and inactivation are caused by microRNA, gene mutation, and loss of heterozygosity in human tumors, which participates in tumor progression. KLF17 low expression increases cancer metastatic viability; its mechanism is that low KLF17 mediates epithelial-mesenchymal transition (EMT) through regulating EMT-related genes expression; the reduced-KLF17 also increases cancer metastasis though upregulating inhibitor of DNA binding 1 (ID1). Additionally, mutant p53 proteins are capable of developing a complex with KLF17, which mediate the depletion of KLF17 inhibiting EMT gene transcription and increases cancer metastasis. KLF17 downregulation also mediates the activation of TGF-β pathway.

DNA damage induces GDNF secretion in the tumor microenvironment with paracrine effects promoting prostate cancer treatment resistance

Though metastatic cancers often initially respond to genotoxic therapeutics, acquired resistance is common. In addition to cytotoxic effects on tumor cells, DNA damaging agents such as ionizing radiation and chemotherapy induce injury in benign cells of the tumor microenvironment resulting in the production of paracrine-acting factors capable of promoting tumor resistance phenotypes. In studies designed to characterize the responses of prostate and bone stromal cells to genotoxic stress, we found that transcripts encoding glial cell line-derived neurotrophic factor (GDNF) increased several fold following exposures to cytotoxic agents including radiation, the topoisomerase inhibitor mitoxantrone and the microtubule poison docetaxel. Fibroblast GDNF exerted paracrine effects toward prostate cancer cells resulting in enhanced tumor cell proliferation and invasion, and these effects were concordant with the expression of known GDNF receptors GFRA1 and RET. Exposure to GDNF also induced tumor cell resistance to mitoxantrone and docetaxel chemotherapy. Together, these findings support an important role for tumor microenvironment damage responses in modulating treatment resistance and identify the GDNF signaling pathway as a potential target for improving responses to conventional genotoxic therapeutics.