β-Catenin signaling pathway regulates cisplatin resistance in lung adenocarcinoma cells by upregulating Bcl-xl

Zinc Oxide Nanoparticles and Cancer Chemotherapy: Helpful Tools for Enhancing Chemo-sensitivity and Reducing Side Effects?

Cancer chemotherapy is still a serious challenge. Chemo-resistance and destructive side effects of chemotherapy drugs are the most critical limitations of chemotherapy. Chemo-resistance is the leading cause of chemotherapy failure. Chemo-resistance, which refers to the resistance of cancer cells to the anticancer effects of chemotherapy drugs, is caused by various reasons. Among the most important of these reasons is the increase in the efflux of chemotherapy drugs due to the rise in the expression and activity of ABC transporters, the weakening of apoptosis, and the strengthening of stemness. In the last decade, a significant number of studies focused on the application of nanotechnology in cancer treatment. Considering the anti-cancer properties of zinc, zinc oxide nanoparticles have received much attention in recent years. Some studies have indicated that zinc oxide nanoparticles can target the critical mechanisms of cancer chemo-resistance and enhance the effectiveness of chemotherapy drugs. These studies have shown that zinc oxide nanoparticles can reduce the activity of ABC transporters, increase DNA damage and apoptosis, and attenuate stemness in cancer cells, leading to enhanced chemo-sensitivity. Some other studies have also shown that zinc oxide nanoparticles in low doses can be helpful in minimizing the harmful side effects of chemotherapy drugs. In this article, after a brief overview of the mechanisms of chemo-resistance and anticancer effects of zinc, we will review all these studies in detail.

Nanomedicine Combats Drug Resistance in Lung Cancer

Lung cancer is the second most prevalent cancer and the leading cause of cancer-related death worldwide. Surgery, chemotherapy, molecular targeted therapy, immunotherapy, and radiotherapy are currently available as treatment methods. However, drug resistance is a significant factor in the failure of lung cancer treatments. Novel therapeutics have been exploited to address complicated resistance mechanisms of lung cancer and the advancement of nanomedicine is extremely promising in terms of overcoming drug resistance. Nanomedicine equipped with multifunctional and tunable physiochemical properties in alignment with tumor genetic profiles can achieve precise, safe, and effective treatment while minimizing or eradicating drug resistance in cancer. Here, this work reviews the discovered resistance mechanisms for lung cancer chemotherapy, molecular targeted therapy, immunotherapy, and radiotherapy, and outlines novel strategies for the development of nanomedicine against drug resistance. This work focuses on engineering design, customized delivery, current challenges, and clinical translation of nanomedicine in the application of resistant lung cancer.

Cancer stem cells: a target for overcoming therapeutic resistance and relapse

Cancer stem cells (CSCs) are a small subset of cells in cancers that are thought to initiate tumorous transformation and promote metastasis, recurrence, and resistance to treatment. Growing evidence has revealed the existence of CSCs in various types of cancers and suggested that CSCs differentiate into diverse lineage cells that contribute to tumor progression. We may be able to overcome the limitations of cancer treatment with a comprehensive understanding of the biological features and mechanisms underlying therapeutic resistance in CSCs. This review provides an overview of the properties, biomarkers, and mechanisms of resistance shown by CSCs. Recent findings on metabolic features, especially fatty acid metabolism and ferroptosis in CSCs, are highlighted, along with promising targeting strategies. Targeting CSCs is a potential treatment plan to conquer cancer and prevent resistance and relapse in cancer treatment.

Evaluation of potential targets to enhance the sensitivity of cholangiocarcinoma cells to anticancer drugs

BACKGROUND

Cholangiocarcinoma (CCA) is a highly lethal cancer originated in the biliary tree. Available treatments for CCA are scarcely effective, partly due to mechanisms of chemoresistance, such as aberrant activation of Wnt/β-catenin pathway and dysfunctional p53.

AIM

To evaluate the impact of enhancing the expression of negative regulators of the Wnt/β-catenin pathway (AXIN1, AXIN2, and GSK3B) and the tumor suppressor gene TP53.

METHODS

Gene expression in paired samples of CCA and adjacent non-tumor liver tissue was determined by RT-qPCR and immunohistochemistry (IHC). Using lentiviral vectors, CCA cells were transduced with genes of interest to assess their impact on the resistome (TLDA), apoptosis (annexin V/propidium iodide), and decreased cell viability (MTT).

RESULTS

IHC revealed marked nuclear localization of β-catenin, consistent with Wnt/β-catenin pathway activation. In silico analysis with data from TCGA showed heterogeneous down-regulation of AXIN1, AXIN2, and GSK3B in CCA. Enhancing the expression of AXIN1, AXIN2, and GSK3B in CCA cells was not enough to block the activity of this signaling pathway or significantly modify resistance to 5-FU, gemcitabine, and platinated drugs. Consistent with impaired p53 function, CDKN1A was down-regulated in CCA. Forced TP53 expression induced p21 up-regulation and reduced cell proliferation. Moreover, the resistome was modified (FAS, BAX, TYMP, and CES2 up-regulation along with DHFR, RRM1, and BIRC5 down-regulation), which was accompanied by enhanced sensitivity to some antitumor drugs, mainly platinated drugs.

CONCLUSION

Enhancing TP53 expression, but not that of AXIN1, AXIN2, and GSK3B, in CCA cells may be a useful strategy to sensitize CCA to antitumor drugs.

Natural compounds: Wnt pathway inhibitors with therapeutic potential in lung cancer

The Wnt/β-catenin pathway is abnormally activated in most lung cancer tissues and considered to be an accelerator of carcinogenesis and lung cancer progression, which is closely related to increased morbidity rates, malignant progression, and treatment resistance. Although targeting the canonical Wnt/β-catenin pathway shows significant potential for lung cancer therapy, it still faces challenges owing to its complexity, tumor heterogeneity and wide physiological activity. Therefore, it is necessary to elucidate the role of the abnormal activation of the Wnt/β-catenin pathway in lung cancer progression. Moreover, Wnt inhibitors used in lung cancer clinical trials are expected to break existing therapeutic patterns, although their adverse effects limit the treatment window. This is the first study to summarize the research progress on various compounds, including natural products and derivatives, that target the canonical Wnt pathway in lung cancer to develop safer and more targeted drugs or alternatives. Various natural products have been found to inhibit Wnt/β-catenin in various ways, such as through upstream and downstream intervention pathways, and have shown encouraging preclinical anti-tumor efficacy. Their diversity and low toxicity make them a popular research topic, laying the foundation for further combination therapies and drug development.

A deep tabular data learning model predicting cisplatin sensitivity identifies BCL2L1 dependency in cancer

Cisplatin, a platinum-based chemotherapeutic agent, is widely used as a front-line treatment for several malignancies. However, treatment outcomes vary widely due to intrinsic and acquired resistance. In this study, cisplatin-perturbed gene expression and pathway enrichment were used to define a gene signature, which was further utilized to develop a cisplatin sensitivity prediction model using the TabNet algorithm. The TabNet model performed better (>80 % accuracy) than all other machine learning models when compared to a wide range of machine learning algorithms. Moreover, by using feature importance and comparing predicted ovarian cancer patient samples, BCL2L1 was identified as an important gene contributing to cisplatin resistance. Furthermore, the pharmacological inhibition of BCL2L1 was found to synergistically increase cisplatin efficacy. Collectively, this study developed a tool to predict cisplatin sensitivity using cisplatin-perturbed gene expression and pathway enrichment knowledge and identified BCL2L1 as an important gene in this setting.

Anti-lung Cancer, Anti-microbial, Anti-α-glucosidase, Anti-sorbitol Dehydrogenase, and in silico Studies of Wogonoside and Isoliquiritigenin as Natural Compounds

Natural substances have long been used in cancer treatment, particularly in Chinese or Indian traditional medicine. Natural compounds are defined as chemical molecules that are found in fungus, marine animals, plants, or bacteria and have significant biological and pharmacological effects. Wogonoside and isoliquiritigenin are two well-known examples of plant-derived chemicals. Several modern anti-cancer medications also come from natural sources. The mic test was used to conduct tests on various natural substances' antimicrobial and antifungal properties. MTT assay was used on lung cancer, and normal (HUVEC) cell lines for analyzing of cytotoxicity and anti-lung cancer effects of Wogonoside and Isoliquiritigenin. These Wogonoside and Isoliquiritigenin had high cell death and anti-lung cancer effects against SPC-A-1, SK-LU-1, and 95D cell lines. Among the above cell lines, the best result of anti-cancer properties of Wogonoside and Isoliquiritigenin was gained in the cell line of KATO III. We examined the inhibition effects on two important enzymes using these two compounds and determined the results. PnPG and NADPH were used as substrates for enzymes. IC50 of Wogonoside and Isoliquiritigenin compounds were 18.25±4.18 and 112.64±16.02 nM for α-glucosidase and 54.72±8.61 and 47.12±11.56 nM for sorbitol dehydrogenase, respectively. For Wogonoside, gram-negative bacteria (K. pneumoniae and E. coli) had MIC values of 9.75±0.95 and 13.77±1.43 µg/mL, gram-positive bacteria (E. faecalis and S. aureus) of 37.02±4.52 and 24.85±3.64 µg/mL, respectively. Finally, molecular docking was done for enzyme results and anticancer results. Results of enzymes and antibacterial, antifungal were in level of micromolar that is good impacts. These natural compounds may be anti-diabetic, anticancer, antibacterial candidates for drug design.

Investigation of the Apoptosis Inducing and β-catenin Silencing by Tetradentate Schiff Base Zinc(II) Complex on the T-47D Breast Cancer Cells

INTRODUCTION

Several mechanisms are known for the anticancer effects of cisplatin. However, its most wellknown function involves binding to DNA and activating the DNA damage response.

METHODS

Despite its good effects, the treatment process often leads to chemoresistance and affects the mechanisms that support cell survival, such as pathways that promote cell growth, apoptosis, DNA damage repair, and endocytosis. For this reason, we investigated the effects of a new metal complex (tetradentate Schiff base zinc(II) complex) on breast cancer cells (T-47D). We evaluated its effect on cytotoxicity, apoptosis, and drug resistance in comparison to cisplatin.

RESULTS

The results of the MTT test showed that tetradentate Schiff base zinc(II) complex has good cytotoxicity compared to cisplatin. The IC50 values for the [Zn(SB)]Cl2 complex and cisplatin after 72 h of exposure were equal to 42.1 and 276.1 μM, respectively. Real-time PCR assay confirmed that the [Zn(SB)]Cl2 complex activated the mitochondrial pathway of apoptosis and increased the expression of Bak1 and caspase-3 genes significantly compared to cisplatin. More importantly, the [Zn(SB)]Cl2 was able to reduce the expression of the β-catenin gene, which plays a role in drug resistance, by 0.011 compared to the control.

CONCLUSION

Therefore, we can hope for this new complex because, without the help of any β-catenin silencing agent, it was able to inhibit the drug resistance in the T-47D cell line that overexpresses the β-catenin gene.

Constitutive BAK/MCL1 complexes predict paclitaxel and S63845 sensitivity of ovarian cancer

We previously found that preformed complexes of BAK with antiapoptotic BCL2 proteins predict BH3 mimetic sensitivities in lymphohematopoietic cells. These complexes have not previously been examined in solid tumors or in the context of conventional anticancer drugs. Here we show the relative amount of BAK found in preformed complexes with MCL1 or BCLXL varies across ovarian cancer cell lines and patient-derived xenografts (PDXs). Cells bearing BAK/MCL1 complexes were more sensitive to paclitaxel and the MCL1 antagonist S63845. Likewise, PDX models with BAK/MCL1 complexes were more likely to respond to paclitaxel. Mechanistically, BIM induced by low paclitaxel concentrations interacted preferentially with MCL1 and displaced MCL1-bound BAK. Further studies indicated that cells with preformed BAK/MCL1 complexes were sensitive to the paclitaxel/S63845 combination, while cells without BAK/MCL1 complexes were not. Our study suggested that the assessment of BAK/MCL1 complexes might be useful for predicting response to paclitaxel alone or in combination with BH3 mimetics.

The Role of Notch, Hedgehog, and Wnt Signaling Pathways in the Resistance of Tumors to Anticancer Therapies

Resistance to therapy is the major hurdle in the current cancer management. Cancer cells often rewire their cellular process to alternate mechanisms to resist the deleterious effect mounted by different therapeutic approaches. The major signaling pathways involved in the developmental process, such as Notch, Hedgehog, and Wnt, play a vital role in development, tumorigenesis, and also in the resistance to the various anticancer therapies. Understanding how cancer utilizes these developmental pathways in acquiring the resistance to the multi-therapeutic approach cancer can give rise to a new insight of the anti-therapy resistance mechanisms, which can be explored for the development of a novel therapeutic approach. We present a brief overview of Notch, Hedgehog, and Wnt signaling pathways in cancer and its role in providing resistance to various cancer treatment modalities such as chemotherapy, radiotherapy, molecular targeted therapy, and immunotherapy. Understanding the importance of these molecular networks will provide a rational basis for novel and safer combined anticancer therapeutic approaches for the improvement of cancer treatment by overcoming drug resistance.

Targeting of Deregulated Wnt/β-Catenin Signaling by PRI-724 and LGK974 Inhibitors in Germ Cell Tumor Cell Lines

The majority of patients with testicular germ cell tumors (GCTs) can be cured with cisplatin-based chemotherapy. However, for a subset of patients present with cisplatin-refractory disease, which confers a poor prognosis, the treatment options are limited. Novel therapies are therefore urgently needed to improve outcomes in this challenging patient population. It has previously been shown that Wnt/β-catenin signaling is active in GCTs suggesting that its inhibitors LGK974 and PRI-724 may show promise in the management of cisplatin-refractory GCTs. We herein investigated whether LGK-974 and PRI-724 provide a treatment effect in cisplatin-resistant GCT cell lines. Taking a genoproteomic approach and utilizing xenograft models we found the increased level of β-catenin in 2 of 4 cisplatin-resistant (CisR) cell lines (TCam-2 CisR and NCCIT CisR) and the decreased level of β-catenin and cyclin D1 in cisplatin-resistant NTERA-2 CisR cell line. While the effect of treatment with LGK974 was limited or none, the NTERA-2 CisR exhibited the increased sensitivity to PRI-724 in comparison with parental cell line. Furthermore, the pro-apoptotic effect of PRI-724 was documented in all cell lines. Our data strongly suggests that a Wnt/β-catenin signaling is altered in cisplatin-resistant GCT cell lines and the inhibition with PRI-724 is effective in NTERA-2 CisR cells. Further evaluation of Wnt/β-catenin pathway inhibition in GCTs is therefore warranted.

Mechanisms of resistance to chemotherapy in non-small cell lung cancer

Non-small cell lung cancer (NSCLC), which represents 80-85% of lung cancer cases, is one of the leading causes of human death worldwide. The majority of patients undergo an intensive and invasive treatment regimen, which may include radiotherapy, chemotherapy, targeted therapy, immunotherapy, or a combination of these, depending on disease stage and performance status. Despite advances in therapeutic regimens, the 5-year survival of NSCLC is approximately 20-30%, largely due to diagnosis at advanced stages. Conventional chemotherapy is still the standard treatment option for patients with NSCLC, especially those with advanced disease. However, the emergence of resistance to chemotherapeutic agents (chemoresistance) poses a significant obstacle to the management of patients with NSCLC. Therefore, to develop efficacious chemotherapeutic approaches for NSCLC, it is necessary to understand the mechanisms underlying chemoresistance. Several mechanisms are known to mediate chemoresistance. These include altered cellular targets for chemotherapy, decreased cellular drug concentrations, blockade of chemotherapy-induced cell cycle arrest and apoptosis, acquisition of epithelial-mesenchymal transition and cancer stem cell-like phenotypes, deregulated expression of microRNAs, epigenetic modulation, and the interaction with tumor microenvironments. In this review, we summarize the mechanisms underlying chemoresistance and tumor recurrence in NSCLC and discuss potential strategies to avoid or overcome chemoresistance.

Serum and Glucocorticoid-Inducible Kinase 1 (SGK1) in NSCLC Therapy

Non-small cell lung cancer (NSCLC) remains the most prevalent and one of the deadliest cancers worldwide. Despite recent success, there is still an urgent need for new therapeutic strategies. It is also becoming increasingly evident that combinatorial approaches are more effective than single modality treatments. This review proposes that the serum and glucocorticoid-inducible kinase 1 (SGK1) may represent an attractive target for therapy of NSCLC. Although ubiquitously expressed, SGK1 deletion in mice causes only mild defects of ion physiology. The frequent overexpression of SGK1 in tumors is likely stress-induced and provides a therapeutic window to spare normal tissues. SGK1 appears to promote oncogenic signaling aimed at preserving the survival and fitness of cancer cells. Most importantly, recent investigations have revealed the ability of SGK1 to skew immune-cell differentiation toward pro-tumorigenic phenotypes. Future studies are needed to fully evaluate the potential of SGK1 as a therapeutic target in combinatorial treatments of NSCLC. However, based on what is currently known, SGK1 inactivation can result in anti-oncogenic effects both on tumor cells and on the immune microenvironment. A first generation of small molecules to inactivate SGK1 has already been already produced.

Negative Effect of Reduced NME1 Expression on Recurrence-Free Survival in Early Stage Non-Small Cell Lung Cancer

This study aimed to understand whether the effect of non-metastatic cells 1 (NME1) on recurrence-free survival (RFS) in early stage non-small cell lung cancer (NSCLC) can be modified by β-catenin overexpression and cisplatin-based adjuvant chemotherapy. Expression levels of NME1 and β-catenin were analyzed using immunohistochemistry in formalin-fixed paraffin-embedded tissues from 425 early stage NSCLC patients. Reduced NME1 expression was found in 39% of samples. The median duration of follow-up was 56 months, and recurrence was found in 186 (44%) of 425 patients. The negative effect of reduced NME1 expression on RFS was worsened by cisplatin-based adjuvant chemotherapy (adjusted hazard ratio = 3.26, 95% CI = 1.16–9.17, p = 0.03). β-catenin overexpression exacerbated the effect of reduced NME1 expression on RFS and the negative effect was greater when receiving cisplatin-based adjuvant chemotherapy: among patients treated with cisplatin-based adjuvant chemotherapy, hazard ratios of patients with reduced NME1 expression increased from 5.59 (95% confidence interval (CI) = 0.62–50.91, p = 0.13) to 15.52 (95% CI = 2.94–82.38, p = 0.001) by β-catenin overexpression, after adjusting for confounding factors. In conclusion, the present study suggests that cisplatin-based adjuvant chemotherapy needs to be carefully applied to early stage NSCLC patients with overexpressed β-catenin in combination with reduced NME1 expression.

Emetine Synergizes with Cisplatin to Enhance Anti-Cancer Efficacy against Lung Cancer Cells

Cisplatin is still the primary therapeutic choice for advanced lung cancers without driver mutations. The occurrence of cisplatin resistance is a major clinical problem in lung cancer treatment. The natural extracted agent emetine reportedly has anticancer effects. This study aimed to explore the possible role of emetine in cisplatin resistance. We used cell viability, Western blot, and Wnt reporter assays to show that emetine suppresses proliferation, β-catenin expression, and Wnt/β-catenin signaling in non-small cell lung cancer (NSCLC). The synergism of emetine and cisplatin was assessed by constructing isobolograms and calculating combination index (CI) values using the Chou-Talalay method. Emetine effectively synergized with cisplatin to suppress the proliferation of cancer cells. Furthermore, nuclear β-catenin and cancer stem cell-related markers were upregulated in the cisplatin-resistant subpopulation of CL1-0 cells. Emetine enhanced the anticancer efficacy of cisplatin and synergized with cisplatin in the cisplatin-resistant subpopulation of CL1-0 cells. Taken together, these data suggest that emetine could suppress the growth of NSCLC cells through the Wnt/β-catenin pathway and contribute to a synergistic effect in combination with cisplatin.

Mechanistic Study of TTF-1 Modulation of Cellular Sensitivity to Cisplatin

The lung lineage master regulator gene, Thyroid Transcription Factor-1 (TTF-1, also known as NKX2-1), is used as a marker by pathologists to identify lung adenocarcinomas since TTF-1 is expressed in 60 ~ 70% of lung ADs. Much research has been conducted to investigate roles of TTF-1 in lung cancer biology. But, how it modulates cellular chemosensitivity remains poorly characterized. Our study shows that TTF-1 sensitizes the KRAS-mutated A549 and NCI-H460 lung cancer cells to cisplatin, a common chemotherapy used to treat lung cancer. This chemosensitization activity does not appear to be mediated by a TTF-1-imposed alteration on nucleotide excision repair. Mechanistically, TTF-1 induced a reduction in p-AKT (S473), which in turn activated glycogen synthase kinase 3 (GSK3) and reduced β-catenin. Intriguingly, in the EGFR-mutated NCI-H1975 and HCC827 cells, TTF-1 desensitized these cells to cisplatin; concomitantly, TTF-1 conferred an increase in p-AKT. Finally, the conditioned media of TTF-1-transefected cells sensitized TTF-1- cells to cisplatin, implicating that the TTF-1-driven chemosensitization activity may be dually pronged in both intracellular and extracellular compartments. In short, this study highlights the enigmatic activities of TTF-1 in lung cancer, and calls for future research to optimally manage chemotherapy of patients with TTF-1+ lung ADs.

microRNA-1236-3p Regulates DDP Resistance in Lung Cancer Cells

Lung cancer is a malignant tumor leading to the most cancer-related deaths worldwide. The treatment efficiency of lung cancer remains poor mainly due to chemotherapy drug resistance, including cisplatin. MicroRNAs (miRNAs) are closely related to chemotherapy resistance of tumor cells. Here, we illustrated the underlying mechanism of miR-1236-3p on the DDP resistance in lung cancer cells. In this study, we found that the expression level of miR-1236-3p was significantly decreased in lung cancer tissues and A549 cell line. In addition, the half maximal inhibitory concentration (IC50) of DDP in A549 cells was significantly lower than that in A549/DDP cells, while the expression level of miR-1236-3p was prominently down-regulated in A549/DDP cells. Combining the online tool TargetScan and a dual-luciferase reporter assay, tumor protein, translationally-controlled 1 (TPT1) was proved to be the direct target gene of miR-1236-3p. The MTT and flow cytometry assays demonstrated that up-regulation of miR-1236-3p could markedly inhibit A549/DDP cell proliferation but promote apoptosis, which could be significantly reversed by pcDNA3.1-TPT1 plasmids. Finally, we further demonstrated that miR-1235-3p could restrain the expression levels of TPT1, Pim-3, phosphate-Bcl-2-associated death promoter (p-BAD) and B-cell lymphoma-extra large (Bcl-XL) in A549/DDP cells, while the inhibition could be reversed by pcDNA3.1-TPT1 as well. In a word, our study demonstrated that miR-1236-3p could reverse DDP resistance by modulation of TPT1 gene and inhibition of Pim-3 signaling pathway in lung cancer cells.

The role of tumor microenvironment in therapeutic resistance

Cancer cells undergo unlimited progression and survival owing to activation of oncogenes. However, support of the tumor microenvironment is essential to the formation of clinically relevant tumors. Recent evidence indicates that the tumor microenvironment is a critical regulator of immune escape, progression, and distant metastasis of cancer. Moreover, the tumor microenvironment is known to be involved in acquired resistance of tumors to various therapies. Despite significant advances in chemotherapy and radiotherapy, occurrence of therapeutic resistance leads to reduced efficacy. This review highlights myeloid cells, cancer-associated fibroblasts, and mesenchymal stem cells consisting of the tumor microenvironment, as well as the relevant signaling pathways that eventually render cancer cells to be therapeutically resistant.

Role of β-catenin in cisplatin resistance, relapse and prognosis of head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is one of the most common types of cancer in India with high incidence and rapid recurrence rates. Here, we aimed to investigate the role of β-catenin, a developmental pathway gene, in HNSCC therapy resistance, DNA damage response, recurrence and prognosis.

METHODS

In total 80 HNSCC samples were included. Western blot, immunohistochemistry and qRT-PCR analyses were performed to assess β-catenin expression in the cut margin and tumor areas of each sample. Kaplan-Meier analyses were performed to correlate β-catenin expression with the survival and prognosis of HNSCC patients. In addition, chemo-resistance, DNA damage response and DNA repair capacities were evaluated in HNSCC-derived cell lines through LiCl-mediated up-regulation and siRNA-mediated silencing of β-catenin expression.

RESULTS

We observed β-catenin up-regulation in cut margin areas of recurrent patients compared to their corresponding tumor regions, which subsequently could be associated with poor prognosis. In addition, we found that LiCl-mediated up-regulation of β-catenin in HNSCC-derived cells led to cisplatin resistance, evasion of apoptosis, enhanced DNA repair and enhanced migration. The effects of β-catenin silencing correlated with its putative role in chemo-resistance and DNA damage response.

CONCLUSION

From our results we conclude that β-catenin may contribute to HNSCC therapy resistance and disease relapse. As such, β-catenin may be explored as a therapeutic target along with conventional therapeutics.

Soluble guanylate cyclase stimulators increase sensitivity to cisplatin in head and neck squamous cell carcinoma cells

Head and neck squamous cell carcinoma (HNSCC) is an aggressive and often fatal disease. Cisplatin is the most common chemotherapeutic drug in the treatment of HNSCC, but intrinsic and acquired resistance are frequent, and severe side effects occur at high doses. The second messenger cyclic GMP (cGMP) is produced by soluble guanylate cyclase (sGC). We previously reported that activation of the cGMP signaling cascade caused apoptosis in HNSCC cells, while others found that this pathway enhances cisplatin efficacy in some cell types. Here we found that sGC stimulators reduced HNSCC cell viability synergistically with cisplatin, and enhanced apoptosis by cisplatin. Moreover, the sGC stimulators effectively reduced viability in cells with acquired cisplatin resistance, and were synergistic with cisplatin. The sGC stimulator BAY 41-2272 reduced expression of the survival proteins EGFR and β-catenin, and increased pro-apoptotic Bax, suggesting a potential mechanism for the anti-tumorigenic effects of these drugs. The sGC stimulator Riociguat is FDA-approved to treat pulmonary hypertension, and others are being studied for therapeutic use in several diseases. These drugs could provide valuable addition or alternative to cisplatin in the treatment of HNSCC.