Pluripotency-associated genes in human nasopharyngeal carcinoma CNE-2 cells are reactivated by a unique epigenetic sub-microenvironment

Metabolic Reprogramming and Immune Evasion in Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumor of the nasopharynx mainly characterized by geographic distribution and EBV infection. Metabolic reprogramming, one of the cancer hallmarks, has been frequently reported in NPCs to adapt to internal energy demands and external environmental pressures. Inevitably, the metabolic reprogramming within the tumor cell will lead to a decreased pH value and diverse nutritional supplements in the tumor-infiltrating micro-environment incorporating immune cells, fibroblasts, and endothelial cells. Accumulated evidence indicates that metabolic reprogramming derived from NPC cells may facilitate cancer progression and immunosuppression by cell-cell communications with their surrounding immune cells. This review presents the dysregulated metabolism processes, including glucose, fatty acid, amino acid, nucleotide metabolism, and their mutual interactions in NPC. Moreover, the potential connections between reprogrammed metabolism, tumor immunity, and associated therapy would be discussed in this review. Accordingly, the development of targets on the interactions between metabolic reprogramming and immune cells may provide assistances to overcome the current treatment resistance in NPC patients.

Tumor Blood Flow Is a Predictor of Radiotherapy Response in Patients With Nasopharyngeal Carcinoma

Purpose

The aim of this study was to evaluate tumor blood flow (TBF) as a predictor of radiotherapy response for nasopharyngeal carcinoma (NPC).

Materials and Method

A total of 134 patients were divided into two groups, the complete response (CR) group and the partial response (PR) group based on RECIST 1.1 recommendations. The statistical difference was evaluated for pre- and mid- or post-treatment TBF and changes of TBF for tumors and metastatic lymph nodes between CR and PR, respectively. The receiver operation characteristic (ROC) curve was utilized to evaluate the accuracy of TBF in predicting the response of radiation therapy. The association between TBF and SUVmax was also investigated.

Results

The reduction of TBF in CR was significantly lower than that in PR for primary tumors (P <0.001) and metastatic lymph nodes (P <0.001). The multivariate logistic regression analysis indicated that the reduction of TBF is an independent predictor of the response of radiation therapy for primary tumors (P <0.001) and metastatic lymph nodes (P <0.001). The accuracy of TBF reduction in predicting the response of radiation therapy was 0.817 in primary tumors and 0.924 in metastatic lymph nodes, respectively. No significant correlation was observed between the TBF values and SUVmax of primary tumors (r = -0.008, P = 0.954) and metastasis lymph nodes (r = -0.061, P = 0.652).

Conclusion

This study suggests that the reduction of TBF is a promising parameter for evaluating the response of radiation therapy.

Tumacrophage: macrophages transformed into tumor stem-like cells by virulent genetic material from tumor cells

Tumor-associated macrophages are regarded as tumor-enhancers as they have key roles in the subversion of adaptive immunity and in inflammatory circuits that promote tumor progression. Here, we show that cancer cells can subvert macrophages yielding cells that have gained pro-tumor functions. When macrophages isolated from mice or humans are co-cultured with dead cancer cell line cells, induced to undergo apoptosis to mimic chemotherapy, up-regulation of pro-tumor gene expression was identified. Phagocytosis of apoptotic cancer cells by macrophages resulted in their transformation into tumor stem (initiating)-like cells, as indicated by the expression of epithelial markers (e.g., cytokeratin) and stem cell markers (e.g., Oct4) and their capability to differentiate in vitro and self-renew in serum-free media. Moreover, we identified a subset of monocytes/macrophages cells in the blood of cancer (breast, ovarian and colorectal) patients undergoing chemotherapy that harbor tumor transcripts. Our findings uncover a new role for macrophages in tumor development, where they can be transformed into tumor-like cells, potentially by horizontal gene transfer of tumor-derived genes, thus, by taking advantage of chemotherapy, these transformed macrophages promote tumor metastasis by escaping immune surveillance.

Specific autoantigens identified by sera obtained from mice that are immunized with testicular germ cells alone

There are various autoimmunogenic antigens (AIs) in testicular germ cells (TGCs) recognized as foreign by the body's immune system. However, there is little information of TGC-specific AIs being available. The aim of this study is to identify TGC-specific AIs. We have previously established that immunization using viable syngeneic TGC can also induce murine experimental autoimmune orchitis (EAO) without using any adjuvant. This study is to identify TGC-specific AIs by TGC liquid chromatography-tandem mass spectrometry analysis, followed by two-dimensional gel electrophoresis that reacted with serum IgG from EAO mice. In this study, we identified 11 TGC-specific AIs that reacted with serum from EAO mice. Real-time RT-PCR analysis showed that the mRNA expressions of seven TGC-specific AIs were significantly higher in only mature testis compared to other organs. Moreover, the recombinant proteins of identified 10 (except unnamed protein) TGC-specific AIs were created by using human embryonic kidney 293 (HEK293) cells and these antigencities were reconfirmed by Western blot using EAO serum reaction. These results indicated Atp6v1a, Hsc70t, Fbp1 and Dazap1 were candidates for TGC-specific AIs. Identification of these AIs will facilitate new approaches for understanding infertility and cancer pathogenesis and may provide a basis for the development of novel therapies.

Exposure of tumor-associated macrophages to apoptotic MCF-7 cells promotes breast cancer growth and metastasis

Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer. To clarify the mechanisms underlying the crosstalk between TAMs and cancer stem cells (CSCs) in breast cancer recurrence and metastasis, we used a co-culture model of macrophages and apoptotic human breast cancer cell line MCF-7 cells to investigate the effects of TAMs on MCF-7 in vitro and in vivo. Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay. The macrophages exposed to apoptotic cells also induce an increase in the proportion of CD44⁺/CD24⁻ cancer stem-like cells, as well as their proliferative ability accompanied with an increase in mucin1 (MUC1) expression. During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α. Our results indicate that when cancer cells endure chemotherapy induced apoptosis, macrophages in their microenvironment can then activate cancer stem cells to promote cancer growth and metastasis by secreting IL-6, which activates STAT3 phosphorylation to regulate the transcription of its downstream target genes.

Dysregulation of the PI3K/Akt signaling pathway affects cell cycle and apoptosis of side population cells in nasopharyngeal carcinoma

Increasing evidence has suggested that certain types of cancer possess their own stem-like cells, and that one subset of these cells, termed the side population (SP), may have an important role in tumorigenesis and cancer therapy. However, the molecular mechanisms underlying the modulation of SP cells in nasopharyngeal carcinoma (NPC) have remained elusive. In the present study, it was hypothesized that dysregulation of the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/Akt signaling pathway may influence SP and non-SP (NSP) phenotype. SP cells from the HK-1 NPC cell line were identified, and cancer stem cell markers were found to be highly expressed in SP cells compared with that of NSP cells. Freshly sorted SP cells demonstrated a significant increase in the proportion of cells in G0/G1 phase, while the majority of NSP cells were in the proliferative phase. Following 48 h of culture subsequent to cell sorting, the differences in cell cycle distribution between the SP and NSP cells converged. In addition, the apoptotic ratio of NSP cells was higher than that of SP cells at 24 h following sorting, but had no significant differences 48 h following sorting. To elucidate the potential mechanism mediating the cell cycle and apoptosis in SP cells, the expression levels of key molecules in the PI3K/Akt signaling pathway were evaluated. PI3K and Akt were upregulated, while 14-3-3σ protein was downregulated in SP cells when freshly sorted (0 h). However, there was no significant difference in the expression of these molecules between SP and NSP cells following 48 h of culture. These results suggested that dysregulation of the PI3K/Akt signaling pathway may be associated with the cell cycle and apoptosis of SP cells in NPC. However, further investigation is required to elucidate the detailed mechanisms underlying these effects.

Salivary gland cancer stem cells

Emerging evidence suggests the existence of a tumorigenic population of cancer cells that demonstrate stem cell-like properties such as self-renewal and multipotency. These cells, termed cancer stem cells (CSC), are able to both initiate and maintain tumor formation and progression. Studies have shown that CSC are resistant to traditional chemotherapy treatments preventing complete eradication of the tumor cell population. Following treatment, CSC are able to re-initiate tumor growth leading to patient relapse. Salivary gland cancers are relatively rare but constitute a highly significant public health issue due to the lack of effective treatments. In particular, patients with mucoepidermoid carcinoma or adenoid cystic carcinoma, the two most common salivary malignancies, have low long-term survival rates due to the lack of response to current therapies. Considering the role of CSC in resistance to therapy in other tumor types, it is possible that this unique sub-population of cells is involved in resistance of salivary gland tumors to treatment. Characterization of CSC can lead to better understanding of the pathobiology of salivary gland malignancies as well as to the development of more effective therapies. Here, we make a brief overview of the state-of-the-science in salivary gland cancer, and discuss possible implications of the cancer stem cell hypothesis to the treatment of salivary gland malignancies.

Sorafenib modulates the radio sensitivity of hepatocellular carcinoma cells in vitro in a schedule-dependent manner

BACKGROUND

Hepatocellular carcinoma (HCC) has a high incidence and mortality. Radiotherapy and sorafenib have proven effective for HCC. Here, we investigated whether sorafenib modulated the response of HCC cells to irradiation in vitro, effect of timing of sorafenib, and the underlying mechanisms.

METHODS

Cell viability of the HCC cell lines, SMMC-7721 and Bel-7402, was examined by the 3-(4,5-dimethylthiazol-2-yl)-5(3-carboxymethoxyphenyl)-2(4-sulfophenyl)-2 H-terazolium (MTT) assays. Clonogenic growth assays of SMMC-7721 and Bel-7402 were determined by colony formation assays. DNA damage was assessed by monitoring γ-HAX foci in irradiated cells with immunofluorescence microscopy, and cell cycle distribution changes were examined by flow cytometry. Effects of sorafenib (15 μM) added 30 min prior to radiation (pre-irradiation sorafenib) of SMMC-7721 and BEL-7402 or 24 h post-irradiation (post-irradiation sorafenib) on irradiated SMMC-7721 and BEL-7402 cells were compared to those of radiation alone or no treatment.

RESULTS

The effect of sorafenib was dependent on its time of addition in relationship to irradiation of cells. Pre-irradiation sorafenib did not significantly affect the viability of SMMC-7221 and BEL-7402 cells compared with irradiation treatment alone. In contrast, post-irradiation sorafenib increased the sensitivity of irradiated SMMC-7221 and BEL-7402 cells significantly in a time-dependent manner. Pre-irradiation sorafenib significantly increased the surviving fraction of SMMC-7221 and BEL-7402 cells in clonogenic assays whereas post-irradiation sorafenib significantly reduced the surviving fractions of SMMC-7221 and BEL-7402 cells. SMMC-7721 cells treated with sorafenib 30 min before irradiation had significantly fewer cells with γ-H2AX foci (23.8 ± 2.9%) than SMMC-7721 cells receiving radiation alone (59.9 ± 2.4; P < 0.001). Similarly, BEL-7402 cells receiving sorafenib prior to irradiation had significantly fewer cells with γ-H2AX foci (46.4 ± 3.8%) than those receiving radiation alone (25.0 ± 3.0%; P < 0.001). In addition, irradiation (6 Gy) caused a significant increase in the percentage of both SMMC-7721 and BEL-7402 cells in G2/M at 12 to 16 h post irradiation, which was markedly delayed by pre-irradiation sorafenib.

CONCLUSIONS

Sorafenib combined with irradiation exerted a schedule-dependent effect in HCC cells in vitro, which has significant implications for the combined use of sorafenib and radiotherapy for HCC patients.

Tumor-associated microglia/macrophages enhance the invasion of glioma stem-like cells via TGF-β1 signaling pathway

The invasion of malignant glioma cells into the surrounding normal brain tissues is crucial for causing the poor outcome of this tumor type. Recent studies suggest that glioma stem-like cells (GSLCs) mediate tumor invasion. However, it is not clear whether microenvironment factors, such as tumor-associated microglia/macrophages (TAM/Ms), also play important roles in promoting GSLC invasion. In this study, we found that in primary human gliomas and orthotopical transplanted syngeneic glioma, the number of TAM/Ms at the invasive front was correlated with the presence of CD133(+) GSLCs, and these TAM/Ms produced high levels of TGF-β1. CD133(+) GSLCs isolated from murine transplanted gliomas exhibited higher invasive potential after being cocultured with TAM/Ms, and the invasiveness was inhibited by neutralization of TGF-β1. We also found that human glioma-derived CD133(+) GSLCs became more invasive upon treatment with TGF-β1. In addition, compared with CD133(-) committed tumor cells, CD133(+) GSLCs expressed higher levels of type II TGF-β receptor (TGFBR2) mRNA and protein, and downregulation of TGFBR2 with short hairpin RNA inhibited the invasiveness of GSLCs. Mechanism studies revealed that TGF-β1 released by TAM/Ms promoted the expression of MMP-9 by GSLCs, and TGFBR2 knockdown reduced the invasiveness of these cells in vivo. These results demonstrate that TAM/Ms enhance the invasiveness of CD133(+) GSLCs via the release of TGF-β1, which increases the production of MMP-9 by GSLCs. Therefore, the TGF-β1 signaling pathway is a potential therapeutic target for limiting the invasiveness of GSLCs.

3'-UTR-mediated post-transcriptional regulation of cancer metastasis: beginning at the end

Epithelial-mesenchymal transition (EMT) and the underlying mechanisms and signaling pathways regulating such transitions have generated a lot of interest among cancer researchers. Much of this can be attributed to the apparent similarities in the molecular processes regulating embryonic EMT that can be recapitulated during tumor progression and metastasis. It appears that both embryonic and oncogenic EMT are regulated by an intricate interplay of transcriptional and post-transcriptional programs, and the recent discovery of a transcript-selective translational regulatory pathway controlling expression of EMT-associated mRNAs demonstrates the high fidelity and tight regulation associated with the process of EMT and metastatic progression. Heterogeneous nuclear ribonucleoprotein E1 (hnRNP E1) is emerging as a critical and integral modulator of TGFβ-induced EMT and subsequent tumor metastasis. Through its RNA-binding ability, hnRNP E1 binds distinct 3'-UTR structural elements present in mRNA transcripts required for EMT and translationally silences their expression. Translational silencing, mediated by hnRNP E1, occurs specifically at the translation elongation step through effects on the eukaryotic elongation factor-1 A1 (eEF1A1), and is relieved by Akt2-mediated phosphorylation. Interestingly, modulation of either the steady-state expression or the posttranscriptional modification of hnRNP E1 has a temporo-spatial effect on translational repression, tumorigenesis and cancer metastasis.

Heterogeneous nuclear ribonucleoproteins (hnRNPs) in cellular processes: Focus on hnRNP E1's multifunctional regulatory roles

Heterogeneous nuclear ribonucleoproteins (hnRNPs) comprise a family of RNA-binding proteins. The complexity and diversity associated with the hnRNPs render them multifunctional, involved not only in processing heterogeneous nuclear RNAs (hnRNAs) into mature mRNAs, but also acting as trans-factors in regulating gene expression. Heterogeneous nuclear ribonucleoprotein E1 (hnRNP E1), a subgroup of hnRNPs, is a KH-triple repeat containing RNA-binding protein. It is encoded by an intronless gene arising from hnRNP E2 through a retrotransposition event. hnRNP E1 is ubiquitously expressed and functions in regulating major steps of gene expression, including pre-mRNA processing, mRNA stability, and translation. Given its wide-ranging functions in the nucleus and cytoplasm and interaction with multiple proteins, we propose a post-transcriptional regulon model that explains hnRNP E1's widespread functional diversity.