Butylidenephthalide Abrogates the Snail-Induced Cancer Stemness in Oral Carcinomas

Oral cancer is one of the most common cancers worldwide, especially in South Central Asia. It has been suggested that cancer stem cells (CSC) play crucial roles in tumor relapse and metastasis, and approaches to target CSC may lead to promising results. Here, aldehyde dehydrogenase 1 (ALDH1) and CD44 were utilized to isolate CSCs of oral cancer. Butylidenephthalide, a bioactive phthalide compound from Angelica sinensis, was tested for its anti-CSC effects. MTT assay showed that a lower concentration of butylidenephthalide was sufficient to inhibit the proliferation of patient-derived ALDH1⁺/CD44⁺ cells without affecting normal cells. Administration of butylidenephthalide not only reduced ALDH1 activity and CD44 expression, it also suppressed the migration, invasion, and colony formation abilities of ALDH1⁺/CD44⁺ cells using a transwell system and clonogenic assay. A patient-derived xenograft mouse model supported our in vitro findings that butylidenephthalide possessed the capacity to retard tumor development. We found that butylidenephthalide dose-dependently downregulated the gene and protein expression of Sox2 and Snail. Our results demonstrated that overexpression of Snail in ALDH1^-/CD44^- (non-CSCs) cells induced the CSC phenotypes, whereas butylidenephthalide treatment successfully diminished the enhanced self-renewal and propagating properties. In summary, this study showed that butylidenephthalide may serve as an adjunctive for oral cancer therapy.     

Gene Expression and DNA Methylation in Human Papillomavirus Positive and Negative Head and Neck Squamous Cell Carcinomas

High-risk human papillomaviruses (HPV) are important agents, responsible for a large percentage of the 745,000 cases of head and neck squamous cell carcinomas (HNSCC), which were identified worldwide in 2020. In addition to being virally induced, tobacco and heavy alcohol consumption are believed to cause DNA damage contributing to the high number of HNSCC cases. Gene expression and DNA methylation differ between HNSCC based on HPV status. We used publicly available gene expression and DNA methylation profiles from the Cancer Genome Atlas and compared HPV positive and HPV negative HNSCC groups. We used differential gene expression analysis, differential methylation analysis, and a combination of these two analyses to identify the differences. Differential expression analysis identified 1854 differentially expressed genes, including PCNA, TNFRSF14, TRAF1, TRAF2, BCL2, and BIRC3. SYCP2 was identified as one of the top deregulated genes in the differential methylation analysis and in the combined differential expression and methylation analyses. Additionally, pathway and ontology analyses identified the extracellular matrix and receptor interaction pathway as the most altered between HPV negative and HPV positive HNSCC groups. Combining gene expression and DNA methylation can help in elucidating the genes involved in HPV positive HNSCC tumorigenesis, such as SYCP2 and TAF7L.     

Identification of Tumor-Suppressive miR-30e-3p Targets: Involvement of SERPINE1 in the Molecular Pathogenesis of Head and Neck Squamous Cell Carcinoma

Recently, our studies revealed that some passenger strands of microRNAs (miRNAs) were closely involved in cancer pathogenesis. Analysis of miRNA expression signatures showed that the expression of miR-30e-3p (the passenger strand of pre-miR-30e) was significantly downregulated in cancer tissues. In this study, we focused on miR-30e-3p (the passenger strand of pre-miR-30e). We addressed target genes controlled by miR-30e-3p that were closely associated with the molecular pathogenesis of head and neck squamous cell carcinoma (HNSCC). Ectopic expression assays demonstrated that the expression of miR-30e-3p attenuated cancer cell malignant phenotypes (e.g., cell proliferation, migration, and invasive abilities). Our analysis of miR-30e-3p targets revealed that 11 genes (ADA, CPNE8, C14orf126, ERGIC2, HMGA2, PLS3, PSMD10, RALB, SERPINE1, SFXN1, and TMEM87B) were expressed at high levels in HNSCC patients. Moreover, they significantly predicted the short survival of HNSCC patients based on 5-year overall survival rates (p < 0.05) in The Cancer Genome Atlas (TCGA). Among these targets, SERPINE1 was found to be an independent prognostic factor for patient survival (multivariate Cox regression; hazard ratio = 1.6078, p < 0.05). Aberrant expression of SERPINE1 was observed in HNSCC clinical samples by immunohistochemical analysis. Functional assays by targeting SERPINE1 expression revealed that the malignant phenotypes (e.g., proliferation, migration, and invasion abilities) of HNSCC cells were suppressed by the silencing of SERPINE1 expression. Our miRNA-based approach will accelerate our understanding of the molecular pathogenesis of HNSCC.     

Differential Angiogenic Potential of 3-Dimension Spheroid of HNSCC Cells in Mouse Xenograft

The experimental animal model is still essential in the development of new anticancer drugs. We characterized mouse tumors derived from two-dimensional (2D) monolayer cells or three-dimensional (3D) spheroids to establish an in vivo model with highly standardized conditions. Primary cancer-associated fibroblasts (CAFs) were cultured from head and neck squamous cell carcinoma (HNSCC) tumor tissues and co-injected with monolayer cancer cells or spheroids into the oral mucosa of mice. Mice tumor blood vessels were stained, followed by tissue clearing and 3D Lightsheet fluorescent imaging. We compared the effect of exosomes secreted from 2D or 3D culture conditions on the angiogenesis-related genes in HNSCC cells. Our results showed that both the cells and spheroids co-injected with primary CAFs formed tumors. Interestingly, vasculature was abundantly distributed inside the spheroid-derived but not the monolayer-derived mice tumors. In addition, cisplatin injection more significantly decreased spheroid-derived but not monolayer-derived tumor size in mice. Additionally, exosomes isolated from co-culture media of FaDu spheroid and CAF upregulated angiogenesis-related genes in HNSCC cells as compared to exosomes from FaDu cell and CAF co-culture media under in vitro conditions. The mouse tumor xenograft model derived from 3D spheroids of HNSCC cells with primary CAFs is expected to produce reliable chemotherapy drug screening results given the robust angiogenesis and lack of necrosis inside tumor tissues.     

Circular Sponge against miR-21 Enhances the Antitumor Activity of Doxorubicin against Breast Cancer Cells

Breast cancer is the most common type of cancer in women, with chemotherapy being the main strategy. However, its effectiveness is reduced by drug resistance mechanisms. miR-21 is upregulated in breast cancer that has been linked to drug resistance and carcinogenic processes. Our aim was to capture miR-21 with a circular sponge (Circ-21) and thus inhibit the carcinogenic processes and drug resistance mechanisms in which it participates. Proliferation, migration, colony formation, cell cycle, and poly [ADP-ribose] polymerase 1 (PARP-1) and vascular endothelial growth factor (VEGF) detection assays were performed with MCF7 breast cancer cells and MCF10A non-tumor cells. In addition, doxorubicin resistance tests and detection of drug resistance gene expression were performed in MCF7 cells. Reduction in proliferation, as well as migration and colony formation, increased PARP-1 expression, inhibition of VEGF expression and cell cycle arrest in G2/M phase were displayed in the Circ-21 MCF7, which were not observed in the MCF10A cells. Furthermore, in the MCF7 cells, the Circ-21 enhanced the antitumor activity of doxorubicin and decreased the expression of resistance genes: ABCA1, ABCC4, and ABCC5. Based on these results, the use of Circ-21 can be considered a first step for the establishment of an effective gene therapy in the treatment of breast cancer.     

Impact of Oncogenic Targets by Tumor-Suppressive miR-139-5p and miR-139-3p Regulation in Head and Neck Squamous Cell Carcinoma

We newly generated an RNA-sequencing-based microRNA (miRNA) expression signature of head and neck squamous cell carcinoma (HNSCC). Analysis of the signature revealed that both strands of some miRNAs, including miR-139-5p (the guide strand) and miR-139-3p (the passenger strand) of miR-139, were downregulated in HNSCC tissues. Analysis of The Cancer Genome Atlas confirmed the low expression levels of miR-139 in HNSCC. Ectopic expression of these miRNAs attenuated the characteristics of cancer cell aggressiveness (e.g., cell proliferation, migration, and invasion). Our in silico analyses revealed a total of 28 putative targets regulated by pre-miR-139 (miR-139-5p and miR-139-3p) in HNSCC cells. Of these, the GNA12 (guanine nucleotide-binding protein subunit alpha-12) and OLR1 (oxidized low-density lipoprotein receptor 1) expression levels were identified as independent factors that predicted patient survival according to multivariate Cox regression analyses (p = 0.0018 and p = 0.0104, respectively). Direct regulation of GNA12 and OLR1 by miR-139-3p in HNSCC cells was confirmed through luciferase reporter assays. Moreover, overexpression of GNA12 and OLR1 was detected in clinical specimens of HNSCC through immunostaining. The involvement of miR-139-3p (the passenger strand) in the oncogenesis of HNSCC is a new concept in cancer biology. Our miRNA-based strategy will increase knowledge on the molecular pathogenesis of HNSCC.     

Establishment of a p53 Null Murine Oral Carcinoma Cell Line and the Identification of Genetic Alterations Associated with This Carcinoma

Head and neck squamous cell carcinoma (HNSCC), including oral squamous cell carcinoma (OSCC), ranks sixth in cancer incidence worldwide. To generate OSCC cells lines from human or murine tumors, greatly facilitates investigations into OSCC. This study describes the establishing of a mouse palatal carcinoma cell line (designated MPC-1) from a spontaneous tumor present in a heterozygous p53 gene loss C57BL/6 mouse. A MPC-1-GFP cell subclone was then generated by lentivirus infection resulting in stable expression of green fluorescent protein. Assays indicated that MPC-1 was a p53 null polygonal cell that was positive for keratinocyte markers; it also expressed vimentin and showed a loss of E-cadherin expression. Despite that MPC-1 having strong proliferation and colony formation capabilities, the potential for anchorage independent growth and tumorigenesis was almost absent. Like other murine MOC-L and MTCQ cell line series we have previously established, MPC-1 also expresses a range of stemness markers, various oncogenic proteins, and a number of immune checkpoint proteins at high levels. However, the synergistic effects of the CDK4/6 inhibitor palbociclib on other therapeutic drugs were not observed with MPC-1. Whole exon sequencing revealed that there were high rates of non-synonymous mutations in MPC-1 affecting various genes, including Akap9, Arap2, Cdh11, Hjurp, Mroh2a, Muc4, Muc6, Sp110, and Sp140, which are similar to that the mutations present in a panel of chemical carcinogenesis-related murine tongue carcinoma cell lines. Analysis has highlighted the dis-regulation of Akap9, Cdh11, Muc4, Sp110, and Sp140 in human HNSCC as indicated by the TCGA and GEO OSCC databases. Sp140 expression has also been associated with patient survival. This study describes the establishment and characterization of the MPC-1 cell line and this new cell model should help to advance genetic research into oral cancer.     

An Emerging Role for Calcium Signaling in Cancer-Associated Fibroblasts

Tumors exist in a complex milieu where interaction with their associated microenvironment significantly contributes to disease progression. Cancer-associated fibroblasts (CAFs) are the primary component of the tumor microenvironment and participate in complex bidirectional communication with tumor cells. CAFs support the development of various hallmarks of cancer through diverse processes, including direct cell–cell contact, paracrine signaling, and remodeling and deposition of the extracellular matrix. Calcium signaling is a key second messenger in intra- and inter-cellular signaling pathways that contributes to cancer progression; however, the links between calcium signaling and CAFs are less well-explored. In this review, we put into context the role of calcium signaling in interactions between cancer cells and CAFs, with a focus on migration, proliferation, chemoresistance, and genetic instability.     

Anti-Cancer Effects and Tumor Marker Role of Glutathione S-Transferase Mu 5 in Human Bladder Cancer

Our previous study demonstrated that the glutathione S-transferase Mu 5 (GSTM5) gene is highly CpG-methylated in bladder cancer cells and that demethylation by 5-aza-dC activates GSTM5 gene expression. The aim of the present study was to investigate the role of GSTM5 in bladder cancer. The levels of GSTM5 gene expression and DNA methylation were analyzed in patients with bladder cancer, and functional studies of GSTM5 were conducted using GSTM5 overexpression in cultured bladder cancer cells. Clinical analysis revealed that the GSTM5 mRNA expression was lower in bladder cancer tissues than in normal tissues and that the level of GSTM5 DNA methylation was higher in bladder cancer tissues than in normal urine pellets. Overexpression of GSTM5 decreased cell proliferation, migration and colony formation capacity. Glutathione (GSH) assay results indicated that cellular GSH concentration was decreased by GSTM5 expression and that GSH supplementation reversed the decrease in proliferation and migration of cells overexpressing GSTM5. By contrast, a GSH synthesis inhibitor significantly decreased 5637 cell GSH levels, survival and migration. Furthermore, GSTM5 overexpression inhibited the adhesion of cells to the extracellular matrix protein fibronectin. To elucidate the effect of GSTM5 on anticancer drugs used to treat bladder cancer, cellular viability was compared between cells with or without GSTM5 overexpression. GSTM5-overexpressed cells showed no significant change in the cytotoxicity of cisplatin or mitomycin C in 5637, RT4 and BFTC 905 cells. Though a degree of resistance to doxorubicin was noted in 5637 cells overexpressing GSTM5, no such resistance was observed in RT4 and BFTC 905 cells. In summary, GSTM5 plays a tumor suppressor role in bladder cancer cells without significantly affecting chemoresistance to cisplatin and mitomycin C, and the cellular GSH levels highlight a key mechanism underlying the cancer inhibition effect of GSTM5. These findings suggest that low gene expression and high DNA methylation levels of GSTM5 may act as tumor markers for bladder cancer.     

Diclofenac Sensitizes Signet Ring Cell Gastric Carcinoma Cells to Cisplatin by Activating Autophagy and Inhibition of Survival Signal Pathways

Gastric cancer has one of the highest incidence rates of cancer worldwide while also contributing to increased drug resistance among patients in clinical practice. Herein, we have investigated the role of diclofenac (DCF) on sensitizing cisplatin resistance in signet ring cell gastric carcinoma cells (SRCGC). Non-toxic concentrations of DCF significantly augmented cisplatin-induced cell death in cisplatin-resistant SRCGC cells (KATO/DDP) but not in cisplatin-sensitive SRCGC cells (KATOIII). Consistently, concomitant treatment of DCF and cisplatin significantly enhanced autophagic cell death due to overproduction of intracellular reactive oxygen species (ROS). At the molecular level, the induction of ROS has been associated with a reduction in antioxidant enzymes expression while inhibiting nuclear factor erythroid 2-related factor 2 (Nrf2) activity. Moreover, the combination of DCF and cisplatin also inhibited the expression of survival proteins including Bcl-2, Bcl-xL, cIAP1 and cyclin D1 in KATO/DDP cells when compared with cisplatin alone. This was due, at least in part, to reduce MAPKs, Akt, NF-κB, AP-1 and STAT-3 activation. Taken together, our results suggested that DCF potentiated the anticancer effect of cisplatin in SRCGC via the regeneration of intracellular ROS, which in turn promoted cell death as an autophagy mechanism and potentially modulated the cell survival signal transduction pathway.     

Enhanced Chemosensitivity by Targeting Nanog in Head and Neck Squamous Cell Carcinomas

Chemo-resistance is the major cause of high mortality in head and neck squamous cell carcinomas (HNSCC) in which HNSCC-derived cancer stem cells (CSCs) may be involved. Previously, we enriched a subpopulation of HNSCC-derived spheroid cells (SC) (HNSCC-SC) and identified Nanog as a CSCs marker. The aim of this study was to determine the role of Nanog in the chemosensitivity of HNSCC. The functional and clinicopathological studies of Nanog were investigated in HNSCC cells and specimens. Nanog expression was increased in HNSCC cell lines as compared to a normal oral epithelial cell line. Nanog upregulation in clinical tissues from HNSCC patients with recurrent and metastatic specimens relative to the mRNA levels in the samples from normal or primary tissues were examined. Targeting Nanog in HNSCC-SC significantly inhibited their tumorigenic and CSCs-like abilities and effectively increased the sensitivity of HNSCC-SC to chemotherapeutic drug cisplatin treatment. Targeting Nanog in HNSCC-SC showed a synergistic therapeutic effect with cisplatin. Our results suggest that targeting Nanog may have promising therapeutic potential for HNSCC.     

Androgen Receptor Signaling Induces Cisplatin Resistance via Down-Regulating GULP1 Expression in Bladder Cancer

The underlying molecular mechanisms of resistance to cisplatin-based systemic chemotherapy in bladder cancer patients remain to be elucidated, while the link between androgen receptor (AR) activity and chemosensitivity in urothelial cancer has been implicated. Our DNA microarray analysis in control vs. AR knockdown bladder cancer lines identified GULP1 as a potential target of AR signaling. We herein determined the relationship between AR activity and GULP1 expression in bladder cancer cells and then assessed the functional role of GULP1 in cisplatin sensitivity. Androgen treatment in AR-positive cells or AR overexpression in AR-negative cells considerably reduced the levels of GULP1 expression. Chromatin immunoprecipitation further showed direct interaction of AR with the promoter region of GULP1. Meanwhile, GULP1 knockdown sublines were significantly more resistant to cisplatin treatment compared with respective controls. GULP1 knockdown also resulted in a significant decrease in apoptosis, as well as a significant increase in G2/M phases, when treated with cisplatin. In addition, GULP1 was immunoreactive in 74% of muscle-invasive bladder cancers from patients who had subsequently undergone neoadjuvant chemotherapy, including 53% of responders showing moderate (2+)/strong (3+) expression vs. 23% of non-responders showing 2+/3+ expression (P = 0.044). These findings indicate that GULP1 represents a key downstream effector of AR signaling in enhancing sensitivity to cisplatin treatment.     

Lidocaine Sensitizes the Cytotoxicity of Cisplatin in Breast Cancer Cells via Up-Regulation of RARβ2 and RASSF1A Demethylation

It has been reported that lidocaine is toxic to various types of cells. And a recent study has confirmed that lidocaine exerts a demethylation effect and regulates the proliferation of human breast cancer cell lines. To recognize a potential anti-tumor effect of lidocaine, we evaluated the DNA demethylation by lidocaine in human breast cancer lines, MCF-7 and MDA-MB-231 cells, and determined the influence of demethylation on the toxicity to these cells of cisplatin, which is a commonly utilized anti-tumor agent for breast cancer. Results demonstrated that lidocaine promoted a significant global genomic demethylation, and particularly in the promoters of tumor suppressive genes (TSGs), RARβ2 and RASSF1A. Further, the lidocaine treatment increased cisplatin-induced apoptosis and enhanced cisplatin-induced cytotoxicity. The combined treatment with both lidocaine and cisplatin promoted a significantly higher level of MCF-7 cell apoptosis than singular lidocaine or cisplatin treatment. Moreover, the abrogation of RARβ2 or RASSF1A expression inhibited such apoptosis. In conclusion, the present study confirms the demethylation effect of lidocaine in breast cancer cells, and found that the demethylation of RARβ2 and RASSF1A sensitized the cytotoxicity of cisplatin in breast cancer cells.     

Gallotannin from Bouea macrophylla Seed Extract Suppresses Cancer Stem-like Cells and Radiosensitizes Head and Neck Cancer

Cancer stem cells (CSCs) play a critical role in radiation resistance and recurrence. Thus, drugs targeting CSCs can be combined with radiotherapy to improve its antitumor efficacy. Here, we investigated whether a gallotannin extract from Bouea macrophylla seed (MPSE) and its main bioactive compound, pentagalloyl glucose (PGG), could suppress the stemness trait and further confer the radiosensitivity of head and neck squamous cell carcinoma (HNSCC) cell lines. In this study, we evaluate the effect of MPSE or PGG to suppress CSC-like phenotypes and radiosensitization of HNSCC cell lines using a series of in vitro experiments, tumorsphere formation assay, colony formation assay, apoptosis assay, and Western blotting analysis. We demonstrate that MPSE or PGG is able to suppress tumorsphere formation and decrease protein expression of cancer stem cell markers. MPSE or PGG also enhanced the radiosensitivity in HNSCC cells. Pretreatment of cells with MPSE or PGG increased IR-induced DNA damage (γ-H2Ax) and enhanced radiation-induced cell death. Notably, we observed that pretreatment with MPSE or PGG attenuated the IR-induced stemness-like properties characterized by tumorsphere formation and the CD44 CSC marker. Our findings describe a novel strategy for increasing therapeutic efficacy for head and neck cancer patients using the natural products MPSE and PGG.     

Identification of Tumor Suppressive Genes Regulated by miR-31-5p and miR-31-3p in Head and Neck Squamous Cell Carcinoma

We identified the microRNA (miRNA) expression signature of head and neck squamous cell carcinoma (HNSCC) tissues by RNA sequencing, in which 168 miRNAs were significantly upregulated, including both strands of the miR-31 duplex (miR-31-5p and miR-31-3p). The aims of this study were to identify networks of tumor suppressor genes regulated by miR-31-5p and miR-31-3p in HNSCC cells. Our functional assays showed that inhibition of miR-31-5p and miR-31-3p attenuated cancer cell malignant phenotypes (cell proliferation, migration, and invasion), suggesting that they had oncogenic potential in HNSCC cells. Our in silico analysis revealed 146 genes regulated by miR-31 in HNSCC cells. Among these targets, the low expression of seven genes (miR-31-5p targets: CACNB2 and IL34; miR-31-3p targets: CGNL1, CNTN3, GAS7, HOPX, and PBX1) was closely associated with poor prognosis in HNSCC. According to multivariate Cox regression analyses, the expression levels of five of those genes (CACNB2: p = 0.0189; IL34: p = 0.0425; CGNL1: p = 0.0014; CNTN3: p = 0.0304; and GAS7: p = 0.0412) were independent prognostic factors in patients with HNSCC. Our miRNA signature and miRNA-based approach will provide new insights into the molecular pathogenesis of HNSCC.     

Cisplatin-Resistant CD44+ Lung Cancer Cells Are Sensitive to Auger Electrons

Cancer stem cells (CSCs) are resistant to conventional therapy and present a major clinical challenge since they are responsible for the relapse of many cancers, including non-small cell lung cancer (NSCLC). Hence, future successful therapy should also eradicate CSCs. Auger electrons have demonstrated promising therapeutic potential and can induce DNA damage while sparing surrounding cells. Here, we sort primary patient-derived NSCLC cells based on their expression of the CSC-marker CD44 and investigate the effects of cisplatin and a thymidine analog (deoxyuridine) labeled with an Auger electron emitter (¹²⁵I). We show that the CD44⁺ populations are more resistant to cisplatin than the CD44⁻ populations. Interestingly, incubation with the thymidine analog 5-[¹²⁵I]iodo-2′-deoxyuridine ([¹²⁵I]I-UdR) induces equal DNA damage, G2/M cell cycle arrest, and apoptosis in the CD44⁻ and CD44⁺ populations. Our results suggest that Auger electron emitters can also eradicate resistant lung cancer CD44⁺ populations.     

Fundamental and Clinical Applications of Materials Based on Cancer-Associated Fibroblasts in Cancers

Cancer stromal cells play a role in promoting tumor relapse and therapeutic resistance. Therefore, the current treatment paradigms for cancers are usually insufficient to eradicate cancer cells, and anti-cancer therapeutic strategies targeting stromal cells have been developed. Cancer-associated fibroblasts (CAFs) are perpetually activated fibroblasts in the tumor stroma. CAFs are the most abundant and highly heterogeneous stromal cells, and they are critically involved in cancer occurrence and progression. These effects are due to their various roles in the remodeling of the extracellular matrix, maintenance of cancer stemness, modulation of tumor metabolism, and promotion of therapy resistance. Recently, biomaterials and nanomaterials based on CAFs have been increasingly developed to perform gene or protein expression analysis, three-dimensional (3D) co-cultivation, and targeted drug delivery in cancer treatment. In this review, we systematically summarize the current research to fully understand the relevant materials and their functional diversity in CAFs, and we highlight the potential clinical applications of CAFs-oriented biomaterials and nanomaterials in anti-cancer therapy.