p21/waf1 and smooth-muscle actin α expression in stromal fibroblasts of oral cancers

A tumor microenvironment gene set–Based prognostic signature for non-small-cell lung cancer

Background: The tumor microenvironment (TME) is involved in the development and progression of lung carcinomas. A deeper understanding of TME landscape would offer insight into prognostic biomarkers and potential therapeutic targets investigation. To this end, we aimed to identify the TME components of lung cancer and develop a prognostic signature to predict overall survival (OS).

Methods: Expression data was retrieved from The Cancer Genome Atlas (TCGA) database and differentially expressed TME-related genes were calculated between tumor and normal tissues. Then nonnegative matrix factorization (NMF) clustering was used to identify two distinct subtypes.

Results: Our analysis yielded a gene panel consisting of seven TME-related genes as candidate signature set. With this panel, our model showed that the high-risk group experienced a shorter survival time. This model was further validated by an independent cohort with data from Gene Expression Omnibus (GEO) database (GSE50081 and GSE13213). Additionally, we integrated the clinical factors and risk score to construct a nomogram for predicting prognosis. Our data suggested less immune cells infiltration but more fibroblasts were found in tumor tissues derived from patients at high-risk and those patients exhibited a worse immunotherapy response.

Conclusion: The signature set proposed in this work could be an effective model for estimating OS in lung cancer patients. Hopefully analysis of the TME could have the potential to provide novel diagnostic, prognostic and therapeutic opportunities.

Quantitative proteomic profiling of primary cancer-associated fibroblasts in oesophageal adenocarcinoma

BACKGROUND

Cancer-associated fibroblasts (CAFs) form the major stromal component of the tumour microenvironment (TME). The present study aimed to examine the proteomic profiles of CAFs vs. normal fibroblasts (NOFs) from patients with oesophageal adenocarcinoma to gain insight into their pro-oncogenic phenotype.

METHODS

CAFs/NOFs from four patients were sub-cultured and analysed using quantitative proteomics. Differentially expressed proteins (DEPs) were subjected to bioinformatics and compared with published proteomics and transcriptomics  datasets.

RESULTS

Principal component analysis of all profiled proteins showed that CAFs had high heterogeneity and clustered separately from NOFs. Bioinformatics interrogation of the DEPs demonstrated inhibition of adhesion of epithelial cells, adhesion of connective tissue cells and cell death of fibroblast cell lines in CAFs vs. NOFs (p < 0.0001). KEGG pathway analysis showed a significant enrichment of the insulin-signalling pathway (p = 0.03). Gene ontology terms related with myofibroblast phenotype, metabolism, cell adhesion/migration, hypoxia/oxidative stress, angiogenesis, immune/inflammatory response were enriched in CAFs vs. NOFs. Nestin, a stem-cell marker up-regulated in CAFs vs. NOFs, was confirmed to be expressed in the TME with immunohistochemistry.

CONCLUSIONS

The identified pathways and participating proteins may provide novel insight on the tumour-promoting properties of CAFs and unravel novel adjuvant therapeutic targets in the TME.

A CCL8 gradient drives breast cancer cell dissemination

The migration of cancer cells towards gradients of chemoattractive factors represents a potential, yet elusive, mechanism that may contribute to cancer cell dissemination. Here we provide evidence for the maintenance of a gradient of increasing CCL8 concentration between the epithelium, the stroma and the periphery that is instrumental for breast cancer cells’ dissemination. In response to signals elicited by the neoplastic epithelium CCL8 production is enhanced in stromal fibroblasts at the tumor margins and in tissues at which breast cancer cells tend to metastasize such as the lungs and the brain. Manipulation of CCL8 activity influences the histology of the tumors and promotes major steps of the metastatic process such as invasion to adjacent stroma, intravasation and ultimately extravasation and seeding. These findings exemplify how gradients of chemoattractive factors such as CCL8, drive metastasis and suggest that interference with their operation may provide means for breast cancer management.

Therapeutic targeting of replicative immortality

One of the hallmarks of malignant cell populations is the ability to undergo continuous proliferation. This property allows clonal lineages to acquire sequential aberrations that can fuel increasingly autonomous growth, invasiveness, and therapeutic resistance. Innate cellular mechanisms have evolved to regulate replicative potential as a hedge against malignant progression. When activated in the absence of normal terminal differentiation cues, these mechanisms can result in a state of persistent cytostasis. This state, termed "senescence," can be triggered by intrinsic cellular processes such as telomere dysfunction and oncogene expression, and by exogenous factors such as DNA damaging agents or oxidative environments. Despite differences in upstream signaling, senescence often involves convergent interdependent activation of tumor suppressors p53 and p16/pRB, but can be induced, albeit with reduced sensitivity, when these suppressors are compromised. Doses of conventional genotoxic drugs required to achieve cancer cell senescence are often much lower than doses required to achieve outright cell death. Additional therapies, such as those targeting cyclin dependent kinases or components of the PI3K signaling pathway, may induce senescence specifically in cancer cells by circumventing defects in tumor suppressor pathways or exploiting cancer cells' heightened requirements for telomerase. Such treatments sufficient to induce cancer cell senescence could provide increased patient survival with fewer and less severe side effects than conventional cytotoxic regimens. This positive aspect is countered by important caveats regarding senescence reversibility, genomic instability, and paracrine effects that may increase heterogeneity and adaptive resistance of surviving cancer cells. Nevertheless, agents that effectively disrupt replicative immortality will likely be valuable components of new combinatorial approaches to cancer therapy.

Overexpression p21WAF1/CIP1 in suppressing retinal pigment epithelial cells and progression of proliferative vitreoretinopathy via inhibition CDK2 and cyclin E

Background

P21 is one kind of cyclin-dependent kinase inhibitor that can prevent cells from going through the G1/S phase checkpoint and inhibit cell proliferation. Proliferative vitreoretinopathy (PVR) is a proliferative response in the eye. The aim of this study was to determine whether p21^Waf1/Cip1 (p21) suppresses the proliferation and migration of retinal pigment epithelial (RPE) cells in vitro and controls PVR development in vivo.

Methods

Cell cycle analyses and transwell assays were conducted to assess cell proliferation characteristics and the migration ability of RPE cells after transfection with p21. Western blot and reverse-transcription polymerase chain reaction technologies were used to detect the expression of p21, CDK₂ and cyclinE in RPE cells and rabbit retinal tissues. The impact of increasing p21 expression on PVR development was conducted by implantation of an adenovirus vector containing rabbit p21 (rAd-p21) in a PVR rabbit model. The prevalence of PVR and retinal detachment was determined by indirect ophthalmoscopy on days 3, 7, 14, and 21 after the injection of rAd-p21 into the vitreous. B scans and hematoxylin-eosin staining were employed to check rabbit retinas on day 21.

Results

Cell cycle analyses and transwell assays showed that p21 inhibited the proliferation and migration of RPE cells. Increased expression of p21 was detected in cultured RPE cells and rabbit retinas after transfection with the p21 gene, whereas levels of CDK₂ and cyclinE were decreased. The increase in p21 expression effectively suppressed the development of PVR in a rabbit model.

Conclusions

The increase in p21 expression in RPE cells not only inhibits the proliferation and migration of RPE cells in vitro, but also suppresses the development of PVR in vivo, which indicates its therapeutic potential in treating PVR.

Autophagy and senescence in cancer-associated fibroblasts metabolically supports tumor growth and metastasis via glycolysis and ketone production

Senescent fibroblasts are known to promote tumor growth. However, the exact mechanism remains largely unknown. An important clue comes from recent studies linking autophagy with the onset of senescence. Thus, autophagy and senescence may be part of the same physiological process, known as the autophagy-senescence transition (AST). To test this hypothesis, human fibroblasts immortalized with telomerase (hTERT-BJ1) were stably transfected with autophagy genes (BNIP3, CTSB or ATG16L1). Their overexpression was sufficient to induce a constitutive autophagic phenotype, with features of mitophagy, mitochondrial dysfunction and a shift toward aerobic glycolysis, resulting in L-lactate and ketone body production. Autophagic fibroblasts also showed features of senescence, with increased p21(WAF1/CIP1), a CDK inhibitor, cellular hypertrophy and increased β-galactosidase activity. Thus, we genetically validated the existence of the autophagy-senescence transition. Importantly, autophagic-senescent fibroblasts promoted tumor growth and metastasis, when co-injected with human breast cancer cells, independently of angiogenesis. Autophagic-senescent fibroblasts stimulated mitochondrial metabolism in adjacent cancer cells, when the two cell types were co-cultured, as visualized by MitoTracker staining. In particular, autophagic ATG16L1 fibroblasts, which produced large amounts of ketone bodies (3-hydroxy-butyrate), had the strongest effects and promoted metastasis by up to 11-fold. Conversely, expression of ATG16L1 in epithelial cancer cells inhibited tumor growth, indicating that the effects of autophagy are compartment-specific. Thus, autophagic-senescent fibroblasts metabolically promote tumor growth and metastasis, by paracrine production of high-energy mitochondrial fuels. Our current studies provide genetic support for the importance of “two-compartment tumor metabolism” in driving tumor growth and metastasis via a simple energy transfer mechanism. Finally, β-galactosidase, a known lysosomal enzyme and biomarker of senescence, was localized to the tumor stroma in human breast cancer tissues, providing in vivo support for our hypothesis. Bioinformatic analysis of genome-wide transcriptional profiles from tumor stroma, isolated from human breast cancers, also validated the onset of an autophagy-senescence transition. Taken together, these studies establish a new functional link between host aging, autophagy, the tumor microenvironment and cancer metabolism.