Update of research on drug resistance in small cell lung cancer chemotherapy

Marine algae-derived characterized bioactive compounds as therapy for cancer: A review on their classification, mechanism of action, and future perspectives

In 2022, there were around 20 million new cases and over 9.7 million cancer-related deaths worldwide. An increasing number of metabolites with anticancer activity in algae had been isolated and identified, which were promising candidates for cancer therapy. Red algae are well-known for the production of brominated metabolites, including terpenoids and phenols, which have the capacity to induce cell toxicity. Some non-toxic biological macromolecules, including polysaccharides, are distinct secondary metabolites found in many algae, particularly green algae. They possess anticancer activities by inhibiting tumor angiogenesis, stimulating the immune response, and inducing apoptosis. However, the structure-activity relationship between these components and antitumor activity, as well as certain taxa within the algae, remains relatively unstudied. This work is based on the reports published from 2003 to 2024 in PubMed and ISI Web of Science databases. A comprehensive review of the characterized algal anticancer active compounds, together with their structure and mechanism of action was performed. Also, their structure-activity relationship was preliminarily summarized to better assess their potential properties as a natural, safe bioactive product to be used as an alternative for the treatment of cancers, leading to new opportunities for drug discovery.

Intratumoral Abundance of M2-Macrophages is Associated With Unfavorable Prognosis and Markers of T-Cell Exhaustion in Small Cell Lung Cancer Patients

Small cell lung cancer (SCLC) accounts for about 10% to 15% of lung cancer cases. Unlike non-SCLC, therapy options for SCLC are limited, reflected by a 5-year survival rate of about 7%. At the same time, the rise of immunotherapeutic approaches in cancer therapy has rationalized to account for inflammatory phenotypes in tumors. However, the composition of the inflammatory microenvironment in human SCLC is poorly understood to date. In our study, we used in-depth image analysis of virtual whole-slide-images of 45 SCLC tumors and evaluated different markers of M2-macrophages (CD163 and CD204) together with global immunologic markers (CD4, CD8, CD68, CD38, FOXP3, and CD20) and characterized their abundance intratumorally using quantitative image analysis, combined with a deep-learning model for tumor segmentation. In addition, independent scoring, blinded to the results of the computational analysis, was performed by an expert pathologist (A.Q.) of both CD163/CD204 and PD-L1. To this end, we evaluated the prognostic relevance of the abundance of these cell types to overall survival. Given a 2-tier threshold of the median of the M2 marker CD163 within the study population, there was a 12-month overall survival rate of 22% (95% CI, 10%-47%) for patients with high CD163 abundance and 41% (95% CI, 25%-68%) for patients with low CD163 counts. Patients with increased CD163 had a median overall survival of 3 months compared to 8.34 months for patients with decreased CD163 counts (P = .039), which could be confirmed by an expert pathologist (A.Q., P = .018). By analyzing cases with increased CD163 cell infiltrates, a trend for higher FOXP3 counts and PD-L1 positive cells, together with increased CD8 T-cell infiltrates, was observed, which could be confirmed using an independent cohort at the transcriptional level. Together, we showed that markers of M2 were associated with unfavorable outcome in our study cohort.

A Novel NCI-H69AR Drug-Resistant Small-Cell Lung Cancer Mini-Tumor Model for Anti-Cancer Treatment Screening

Small-cell lung cancer is a fast-growing carcinoma with a poor prognosis and a high level of relapse due to multi-drug resistance (MDR). Genetic mutations that lead to the overexpression of efflux transporter proteins can contribute to MDR. In vitro cancer models play a tremendous role in chemotherapy development and the screening of possible anti-cancer molecules. Low-cost and simple in vitro models are normally used. Traditional two-dimensional (2D) models have numerous shortcomings when considering the physiological resemblance of an in vivo setting. Three-dimensional (3D) models aim to bridge the gap between conventional 2D models and the in vivo setting. Some of the advantages of functional 3D spheroids include better representation of the in vivo physiology and tumor characteristics when compared to traditional 2D cultures. During this study, an NCI-H69AR drug-resistant mini-tumor model (MRP1 hyperexpressive) was developed by making use of a rotating clinostat bioreactor system (ClinoStar®; CelVivo ApS, Odense, Denmark). Spheroid growth and viability were assessed over a 25-day period to determine the ideal experimental period with mature and metabolically stable constructs. The applicability of this model for anti-cancer research was evaluated through treatment with irinotecan, paclitaxel and cisplatin for 96 h, followed by a 96 h recovery period. Parameters measured included planar surface area measurements, estimated glucose consumption, soluble protein content, intracellular adenosine triphosphate levels, extracellular adenylate kinase levels, histology and efflux transporter gene expression. The established functional spheroid model proved viable and stable during the treatment period, with retained relative hyperexpression of the MRP1 efflux transporter gene but increased expression of the P-gp transporter gene compared to the cells cultured in 2D. As expected, treatment with the abovementioned anti-cancer drugs at clinical doses (100 mg/m2 irinotecan, 80 mg/m2 paclitaxel and 75 mg/m2 cisplatin) had minimal impact on the drug-resistant mini-tumors, and the functional spheroid models were able to recover following the removal of treatment.

Accurate treatment of small cell lung cancer: Current progress, new challenges and expectations

Small cell lung cancer (SCLC) is a deadly disease with poor prognosis. Fast growing speed, inclination to metastasis, enrichment in cancer stem cells altogether constitute its aggressive nature. In stark contrast to non-small cell lung cancer (NSCLC) that strides vigorously on the road to precision oncology, SCLC has been on the embryonic path to achieve effective personalized treatments. The survival of patients with SCLC have not been improved greatly, which could be possibly due to our inadequate understanding of genetic alterations of SCLC. Recently, encouraging effects have been observed in patients with SCLC undergoing immunotherapy. However, exciting results have only been observed in a small fraction of patients with SCLC, warranting biomarkers predictive of responses as well as novel therapeutic strategies. In addition, SCLC has previously been viewed to be homogeneous. However, perspectives have been changed thanks to the advances in sequencing techniques and platforms, which unfolds the complex heterogeneity of SCLC both genetically and non-genetically, rendering the treatment of SCLC a further step forward into the precision era. To outline the road of SCLC towards precision oncology, we summarize the progresses and achievements made in precision treatment in SCLC in genomic, transcriptomic, epigenetic, proteomic and metabolic dimensions. Moreover, we conclude relevant therapeutic vulnerabilities in SCLC. Clinically tested drugs and clinical trials have also been demonstrated. Ultimately, we look into the opportunities and challenges ahead to advance the individualized treatment in pursuit of improved survival for patients with SCLC.

Cancer-associated fibroblasts strengthen cell proliferation and EGFR TKIs resistance through aryl hydrocarbon receptor dependent signals in non-small cell lung cancer

The tumor microenvironment is a dynamic cellular milieu that interacts with cancer cells and promotes tumor progression and metastasis. However, the specific mechanisms by which the tumor microenvironment impacts cancer cells’ behaviors remain poorly understood. In this study, enriched cancer-associated fibroblasts (CAFs) were observed in tumor tissues isolated from epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) resistant non-small cell lung cancer (NSCLC) patients. CAFs isolated from tumor tissues were capable of producing tryptophan metabolite kynurenine (Kyn), which significantly increased the proliferation and EGFR TKIs resistance of NSCLC cells. In this study, it was further observed that the activation of tryptophan 2,3-dioxygenase (TDO) in CAFs, resulted in the enhanced capability of tryptophan metabolism in them compared to normal fibroblasts. As a result, Kyn produced by CAFs facilitated the up-regulation of Aryl Hydrocarbon Receptor (AhR) signals in NSCLC, thereby resulting in the downstream ATK and ERK signaling pathways activation. Finally, inhibition of AhR signals efficiently prevented tumor growth and development of EGFR TKIs resistance, eventually improved the outcome of EGFR TKIs, and described a promising therapeutic strategy for NSCLC.

The role of emodin on cisplatin resistance reversal of lung adenocarcinoma A549/DDP cell

Exploring drugs that reverse drug resistance and increase the sensitivity of chemotherapy drugs could significantly improve treatment effect of cancer. Our study explored the reversal effect and possible molecular mechanisms of emodin on cisplatin resistance in A549/DDP cells. The IC50 and resistance index of cells were determined by Cell Counting Kit-8 assay. The ability of cell proliferation was evaluated by wound healing assay. Transwell assay was used to detect cell invasion and migration. Apoptosis induction rate was determined by flow cytometry assay and 4',6- diamidino- 2-phenylindole staining. Intracellular concentration was determined by HPLC. Western blot analysis was applied to determine expressions of nuclear factor kappa beta (NF-κB) and its downstream proteins. In this study, we found that the growth inhibitory effect of cisplatin was significantly enhanced by emodin in A549/DDP cells. The combined use of emodin with DDP can effectively promote lung cancer cells apoptosis and inhibit cell migration and invasion. Further investigation indicated that reinforcement effect of emodin and DDP may be associated with inhibition of NF-κB pathway and drug efflux-related proteins such as P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP) and Glutathione S-transferase (GST). The key role of NF-κB was further confirmed by the application of NF-κB inhibitor Ammonium pyrrolidinedithiocarbamate. The intervention of both can significantly increase A549/DDP cell apoptosis and inhibit DDP-induced upregulation of P-gp, MRP and GST. Emodin reverses the cisplatin resistance of tumor cells by down-regulating expression of P-gp, MRP and GST, increasing the intracellular accumulation in A549/DDP cells, and the effect may be associated with the NF-κB pathways.

Knockdown of lncRNA HIF1A-AS2 increases drug sensitivity of SCLC cells in association with autophagy

The aim of this study was to determine the effect of lncRNA HIF1A-AS2 on autophagy-associated drug resistance in small cell lung cancer (SCLC) cells. The expression of HIF1A-AS2 was silenced by siRNA in doxorubicin-sensitive H69 and doxorubicin-resistant H69AR cells. Then, cytotoxicity, apoptosis and autophagy analyses were carried out in the normoxic and CoCl₂-induced hypoxic environment. The effect of HIF1A-AS2 on the expression levels of genes, which are associated with drug resistance and autophagy, was determinated by qRT-PCR analysis. The levels of MRP1, HIF-1α and Beclin-1 were analyzed by western blot method. Knockdown of HIF1A-AS2 increased doxorubicin sensitivity of SCLC cells and decreased autophagy. Knockdown of HIF1A-AS2 has also affected the expression of several genes that will increase drug sensitivity and inhibit autophagy in both cell lines. The levels of HIF-1α and Beclin-1 were decreased in both cell lines by knockdown of HIF1A-AS2. MRP1 expression was decrease in H69AR cells. In addition, CoCl₂-induced hypoxic environment decreased in doxorubicin sensitivity of H69 cells, and knockdown of HIF1A-AS2 reversed this effect of hypoxia. Knockdown of HIF1A-AS2 increased drug sensitivity of SCLC cells in relation to autophagy. Therefore, hypoxia-HIF1A-AS2-autophagy interaction is thought to be determinative in drug sensitivity of these cells.

PI3K/Akt/mTOR signaling orchestrates the phenotypic transition and chemo-resistance of small cell lung cancer

Small cell lung cancer (SCLC) is a phenotypically heterogeneous disease with an extremely poor prognosis, which is mainly attributed to the rapid development of resistance to chemotherapy. However, the relation between the growth phenotypes and chemo-resistance of SCLC remains largely unclear. Through comprehensive bioinformatic analyses, we found that the heterogeneity of SCLC phenotype was significantly associated with different sensitivity to chemotherapy. Adherent or semiadherent SCLC cells were enriched with activation of the PI3K/Akt/mTOR pathway and were highly chemoresistant. Mechanistically, activation of the PI3K/Akt/mTOR pathway promotes the phenotypic transition from suspension to adhesion growth pattern and confers SCLC cells with chemo-resistance. Such chemo-resistance could be largely overcome by combining chemotherapy with PI3K/Akt/mTOR pathway inhibitors. Our findings support that the PI3K/Akt/mTOR pathway plays an important role in SCLC phenotype transition and chemo-resistance, which holds important clinical implications for improving SCLC treatment.

Resveratrol reduces drug resistance of SCLC cells by suppressing the inflammatory microenvironment and the STAT3/VEGF pathway

DNA‐damaging agents, such as doxorubicin (Adriamycin), are widely used for the treatment of small cell lung cancer (SCLC). However, drug resistance is one of the major challenges for treatment of SCLC. Herein, we investigated the mechanisms underlying drug resistance in SCLC cells and the effects of resveratrol (Res) on drug resistance. We report that Adriamycin treatment of H69AR (multidrug resistance phenotype) cells resulted in a lower rate of growth inhibition, up‐regulation of MRP1 and P‐glycoprotein (P‐gp), and higher P‐gp activity as compared with susceptible H69 cells treated with Adriamycin. Moreover, the signal transducer and activator of transcription 3/vascular endothelial growth factor (STAT3/VEGF) pathway was overactivated in H69AR cells, especially after interleukin‐23 treatment. The inflammatory microenvironment promoted the drug resistance of H69AR cells by activating the STAT3/VEGF pathway. The addition of Res suppressed the expression levels of inflammatory mediators, inhibited the STAT3/VEGF pathway, impeded P‐gp activity, and decreased the drug resistance of H69AR cells. H69AR cells exhibited Adriamycin resistance through activation of the STAT3/VEGF pathway, and Res ameliorated the inflammatory microenvironment to suppress the STAT3/VEGF pathway to reduce drug resistance. Our results suggest that Res may have therapeutic potential for SCLC treatment.

Identification and Validation of a Tumor Microenvironment-Related Gene Signature for Prognostic Prediction in Advanced-Stage Non-Small-Cell Lung Cancer

The development of immunotherapy has greatly changed the advanced-stage non-small-cell lung cancer (NSCLC) treatment landscape. The complexity and heterogeneity of tumor microenvironment (TME) lead to discrepant immunotherapy effects among patients at the same pathologic stages. This study is aimed at exploring potential biomarkers of immunotherapy and accurately predicting the prognosis for advanced NSCLC patients. RNA-seq data and clinical information on stage III/IV NSCLC were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). In TCGA-NSCLC with stage III/IV (n = 192), immune scores and stromal scores were calculated by using the ESTIMATE algorithms. Univariate, LASSO, and multivariate Cox regression analyses were performed to screen prognostic TME-related genes (TMERGs) and constructed a gene signature risk score model. It was validated in external dataset including GSE41271 (n = 91) and GSE81089 (n = 36). Additionally, a nomogram incorporating TMERG signature risk score and clinical characteristics was established. Further, we accessed the proportion of 22 types of tumor-infiltrating immune cells (TIIC) from the CIBERSORT website and analyzed the difference between two risk groups. OS of patients with high immune/stromal scores were higher (log-rank P = 0.044/log-rank P = 0.048). Multivariate Cox regression identified six prognostic TMERGs, including CD200, CHI3L2, CNTN1, CTSL, FYB1, and SLC52A1. We developed a six-gene risk score model, which was validated as an independent prognostic factor for OS (HR: 3.32, 95% CI: 2.16-5.09). Time-ROC curves showed useful discrimination for TCGA-NSCLC cohort (1-, 2-, and 3-year AUCs were 0.718, 0.761, and 0.750). The predictive robustness was validated in the external dataset. The C-index and 1-, 2-, and 3-year AUCs of nomogram were the largest, which demonstrated the nomogram had the greatest predictive accuracy and effectiveness and could be used for clinical guidance. Besides, the increased infiltration of T cells regulatory (Tregs) and macrophages M2 in the high-risk group suggested that chronic inflammation may reduce survival probability in patients with advanced NSCLC. We conducted a comprehensive analysis of the tumor microenvironment and identified the TMERG signature, which could predict prognosis accurately and provide a reference for the personalized immunotherapy for advanced NSCLC patients.

Dysregulated Pyrimidine Biosynthesis Contributes to 5-FU Resistance in SCLC Patient-Derived Organoids but Response to a Novel Polymeric Fluoropyrimidine, CF10

Chemo-immunotherapy is central to the treatment of small cell lung cancer (SCLC). Despite modest progress made with the addition of immunotherapy, current cytotoxic regimens display minimal survival benefit and new treatments are needed. Thymidylate synthase (TS) is a well-validated anti-cancer drug target, but conventional TS inhibitors display limited clinical efficacy in refractory or recurrent SCLC. We performed RNA-Seq analysis to identify gene expression changes in SCLC biopsy samples to provide mechanistic insight into the potential utility of targeting pyrimidine biosynthesis to treat SCLC. We identified systematic dysregulation of pyrimidine biosynthesis, including elevated TYMS expression that likely contributes to the lack of efficacy for current TS inhibitors in SCLC. We also identified E2F1-3 upregulation in SCLC as a potential driver of TYMS expression that may contribute to tumor aggressiveness. To test if TS inhibition could be a viable strategy for SCLC treatment, we developed patient-derived organoids (PDOs) from human SCLC biopsy samples and used these to evaluate both conventional fluoropyrimidine drugs (e.g., 5-fluorouracil), platinum-based drugs, and CF10, a novel fluoropyrimidine polymer with enhanced TS inhibition activity. PDOs were relatively resistant to 5-FU and while moderately sensitive to the front-line agent cisplatin, were relatively more sensitive to CF10. Our studies demonstrate dysregulated pyrimidine biosynthesis contributes to drug resistance in SCLC and indicate that a novel approach to target these pathways may improve outcomes.

Icotinib and pemetrexed in treatment of lung adenocarcinoma and the effects on prognostic survival rate of patients

Efficacy comparison of icotinib and pemetrexed in the treatment of lung adenocarcinoma and the effects on the prognostic survival rate of patients were investigated. A retrospective analysis was performed in 132 lung adenocarcinoma patients who were treated in the Affiliated Hospital of Weifang Medical University from July 2010 to July 2015. Among them, 69 patients were treated with icotinib (icotinib group), and 63 patients were treated with pemetrexed (pemetrexed group). In the icotinib group, 125 mg icotinib was orally administered continuously, 3 times a day, until progressive disease or intolerable adverse reactions occurred. In the pemetrexed group, 500 mg/m² pemetrexed was intravenously dripped for a total of 4 cycles, 21 days for 1 cycle, until progressive disease or intolerable adverse reactions occurred. The efficacy, toxic and side effects, and survival rate of the two groups were evaluated. There was a statistically significant difference in toxic and side effects between the two groups of drugs after the treatment of lung adenocarcinoma (P<0.05). The median survival time of patients was 16 months in the icotinib group and 10 months in the pemetrexed group, with a statistically significant difference (P<0.05). The 1-year survival rate was higher in the icotinib group than that in the pemetrexed group (P<0.05). There was no difference in 2- and 3-year survival rates between the two groups (P>0.05). In conclusion, the clinical efficacy of icotinib is similar to that of pemetrexed in the treatment of lung adenocarcinoma, but icotinib has less adverse reactions, with better improvement in disease control.

Circulating tumor cell interactions with macrophages: implications for biology and treatment

Cancer and metastasis are closely associated with inflammation. Macrophages are important effector cells in enhancing tumor proliferation, invasion and providing protection against the immune system. Despite advanced knowledge of tumor-macrophage interactions, the role of macrophages in emergence and invasion of circulating tumor cells (CTCs) is not known. A series of six CTC cell lines have been derived from blood of patients with extensive disease small cell lung cancer (ED-SCLC) in our lab, most likely representing a homogenous cell population of the actual metastasis-initiating cells (MIC) of CTCs. SCLC has an unfavorable prognosis due to rapid dissemination and early chemoresistant relapses. SCLC CTCs recruit macrophages and elicit secretion of various cytokines and the six CTC lines express chitinase-3-like-1 (CHI3L1), vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP9) in abundance. CHI3L1 is cytokine/growth factor expressed in inflammation and cancer and found to be correlated to metastasis and a dismal prognosis. In conclusion, SCLC CTCs have acquired the essential means for aggressiveness and invasion in a tumor microenvironment specifically shaped by macrophages and inflammation.

Apoptosis of Lewis Lung Carcinoma Cells Induced by Microwave via p53 and Proapoptotic Proteins In vivo

Background:

Microwave therapy is a minimal invasive procedure and has been employed in clinical practice for the treatment of various types of cancers. However, its therapeutic application in non-small-cell lung cancer and the underlying mechanism remains to be investigated. This study aimed to investigate its effect on Lewis lung carcinoma (LLC) tumor in vivo.

Methods:

Fifty LLC tumor-bearing C57BL/6 mice were adopted to assess the effect of microwave radiation on the growth and apoptosis of LLC tumor in vivo. These mice were randomly assigned to 10 groups with 5 mice in each group. Five groups were treated by single pulse microwave at different doses for different time, and the other five groups were radiated by multiple-pulse treatment of a single dose. Apoptosis of cancer cells was determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. Western blotting was applied to detect the expression of proteins.

Results:

Single pulse of microwave radiation for 5 min had little effect on the mice. Only 15-min microwave radiation at 30 mW/cm² significantly increased the mice body temperature (2.20 ± 0.82)°C as compared with the other groups (0.78 ± 0.29 °C, 1.24 ± 0.52 °C, 0.78 ± 0.42 °C, respectively), but it did not affect the apoptosis of LLC tumor cells significantly. Continous microwave radiation exposure, single dose microwave radiation once per day for up to seven days, inhibited cell division and induced apoptosis of LLC tumor cells in a dose- and duration-dependent manner. It upregulated the protein levels of p53, Caspase 3, Bax and downregulated Bcl-2 protein.

Conclusions:

Multiple exposures of LLC-bearing mice to microwave radiation effectively induced tumor cell apoptosis at least partly by upregulating proapoptotic proteins and downregulating antiapoptotic proteins. Continuous radiation at low microwave intensity for a short time per day is promising in treating non-small-cell lung cancer.

Timing of thoracic radiotherapy in limited stage small cell lung cancer: results of early versus late irradiation from a single institution in Turkey

BACKGROUND

It is standard treatment to combine chemotherapy (CT) and thoracic radiotherapy (TRT) in treating patients with limited stage small cell lung cancer (LS-SCLC). However, optimal timing of TRT is unclear. We here evaluated the survival impact of early versus late TRT in patients with LS-SCLC.

MATERIALS AND METHODS

Follow-up was retrospectively analyzed for seventy consecutive LS-SCLC patients who had successfully completed chemo-TRT between January 2006 and January 2012. Patients received TRT after either 1 to 2 cycles of CT (early TRT) or after 3 to 6 cycles of CT (late TRT). Survival and response rates were evaluated using the Kaplan-Meier method and comparisons were made using the multivariate Cox regression test.

RESULTS

Median follow-up was 24 (5 to 57) months. Carboplatin+etoposide was the most frequent induction CT (59%). Median overall, disease free, and metastasis free survivals in all patients were 15 (5 to 57), 5 (0 to 48) and 11 (3 to 57) months respectively. Late TRT was superior to early TRT group in terms of response rate (p=0.05). 3 year overall survival (OS) rates in late versus early TRT groups were 31% versus 17%, respectively (p=0.03). Early TRT (p=0.03), and incomplete response to TRT (p=0.004) were negative predictors of OS. Significant positive prognostic factors for distant metastasis free survival were late TRT (p=0.03), and use of PCI (p=0.01). Use of carboplatin versus cisplatin for induction CT had no significant impact on OS (p=0.634), DFS (p=0.727), and MFS (p=0.309).

CONCLUSIONS

Late TRT appeared to be superior to early TRT in LS-SCLC treatment in terms of complete response, OS and DMFS. Carboplatin or cisplatin can be combined with etoposide in the induction CT owing to similar survival outcomes.

Relationship between the SER treatment period and prognosis of patients with small cell lung cancer

PURPOSE

To explore the relationship between SER (time between the start of any treatment and the end of radiation therapy) and the survival of patients with limited-stage small cell lung cancer.

MATERIALS AND METHODS

Between 2008 and 2013, 135 cases of limited-stage small cell lung cancer (LS-SCLC) treated with consecutively curative chemoradiotherapy were included in this retrospective analysis. In terms of SER, patients were divided into early radiotherapy group (SER<30 days, n=76) and late radiotherapy group (SER≥30 days, n=59) with a cut- off of SER 30 days. Outcomes of the two groups were compared for overall survival.

RESULTS

For all analyzable patients, median follow-up time was 23.8 months and median overall survival time was 16.8 months. Although there was no significant differences in distant metastasis free survival between the two groups, patients in early radiotherapy group had a significantly better PFS (p=0.003) and OS (p=0.000).

CONCLUSIONS

A short SER may be a good prognostic factor for LD-SCLC patients treated with concurrent chemoradiotherapy.

Silencing of AP-4 inhibits proliferation, induces cell cycle arrest and promotes apoptosis in human lung cancer cells

Activating enhancer-binding protein (AP)-4 is a member of the basic helix-loop-helix transcription factors, and is involved in tumor biology. However, the role of AP-4 in human lung cancer remains to be fully elucidated. In the present study, the expression of AP-4 in human lung cancer tissues and cells was investigated by reverse transcription-quantitative polymerase chain reaction, and it was observed that the level of AP-4 was increased in tumor tissues and cells compared with their normal counterparts. AP-4 expression was knocked down by transfection with a specific small interfering RNA (siRNA) in lung cancer cells, and this indicated that siRNA-mediated silencing of AP-4 inhibited cell proliferation, arrested the cell cycle at the G0/G1 phase and induced apoptosis by modulating the expression of p21 and cyclin D1. The results of the present study suggest that AP-4 may be an oncoprotein that has a significant role in lung cancer, and that siRNA-mediated silencing of AP-4 may have therapeutic potential as a strategy for the treatment of lung cancer.

Pharmacophore Development for Anti-Lung Cancer Drugs

Lung cancer is one particular type of cancer that is deadly and relatively common than any other. Treatment is with chemotherapy, radiation therapy and surgery depending on the type and stage of the disease. Focusing on drugs used for chemotherapy and their associated side effects, there is a need to design and develop new anti-lung cancer drugs with minimal side effects and improved efficacy. The pharmacophore model appears to be a very helpful tool serving in the designing and development of new lead compounds. In this paper, pharmacophore analysis of 10 novel anti-lung cancer compounds was validated for the first time. Using LigandScout the pharmacophore features were predicted and 3D pharmacophores were extracted via VMD software. A training set data was collected from literature and the proposed model was applied to the training set whereby validating and verifying similar activity as that of the most active compounds was achieved. Therefore pharmacophore develoipment could be recommended for further studies.

Drug resistance effects of ribosomal protein L24 overexpression in hepatocellular carcinoma HepG2 cells

BACKGROUND

The morbidity and mortality rate of liver cancer continues to rise in China and advanced cases respond poorly to chemotherapy. Ribosomal protein L24 has been reported to be a potential therapeutic target whose depletion or acetylation inhibits polysome assembly and cell growth of cancer.

MATERIALS AND METHODS

Total RNA of cultured amycin-resistant and susceptible HepG2 cells was isolated, and real time quantitative RT-PCR were used to indicate differences between amycin-resistant and susceptible strains of HepG2 cells. Viability assays were used to determine amycin resistance in RPL24 transfected and control vector and null- transfected HepG2 cell lines.

RESULTS

The ribosomal protein L24 transcription level was 7.7 times higher in the drug-resistant HepG2 cells as compared to susceptible cells on quantitative RT-PCR analysis. This was associated with enhanced drug resistance as determined by methyl tritiated thymidine (3H-TdR) incorporation.

CONCLUSIONS

The ribosomal protein L24 gene may have effects on drug resistance mechanisms in hepatocellular carcinoma HepG2 cells.

Smoking, inflammation and small cell lung cancer: recent developments

Small cell lung cancer (SCLC) accounts for 15 % of all lung tumors and represents an invasive neuroendocrine malignancy with poor survival rates. This cancer is highly prevalent in smokers and characterized by inactivation of p53 and retinoblastoma. First in vitro expansion of circulating tumor cells (CTCs) of SCLC patients allowed for investigation of the cell biology of tumor dissemination. In the suggested CTC SCLC model, the primary tumor attracts and educates tumor-promoting and immunosuppressive macrophages which in turn arm CTCs to spread and generate distal lesions. Preexisting inflammatory processes associated with chronic obstructive pulmonary disease (COPD) seem to potentiate the subsequent activity of tumor-associated macrophages (TAM). Activation of signal transducer and activator of transcription 3 (STAT3) and expression of chitinase-3-like 1/YKL-40 in SCLC CTCs seems to be associated with drug resistance. In conclusion, inflammation-associated generation of invasive and chemoresistant CTCs most likely explains the characteristic features of SCLC, namely early dissemination and rapid failure of chemotherapy.

Optimal timing of radiotherapy with alternating/sequential radio-chemotherapy for limited-stage small cell lung cancer

OBJECTIVE

To investigate the optimal timing of radiotherapy with alternating/sequential radio-chemotherapy for limited-stage small cell lung cancer (LS-SCLC).

METHODS

91 patients with LS-SCLC were retrospectively analyzed and divided into two groups according to the number of chemotherapy cycles before radiotherapy. If the patient received radiotherapy after 3 cycles or fewer cycles of chemotherapy, classification was into the early group, if not, into the late group. All patients received 6 cycles of standard chemotherapy (EP/EC) and conventional radiotherapy (56 gy~ 60 gy/28 f ~30 f).

RESULTS

The response rate (RR) of the early and late groups were 85.7% and 81.6%, respectively, with no significant difference (p>0.05). In contrast, the progression-free survival (PFS) in the early group was better than that in the late group (11.8 months vs 9.86 months), and the difference was significant (p<0.05). There was no significant difference between two groups in adverse reactions, which gastrointestinal irritation and bone marrow suppression being the most common (p>0.05).

CONCLUSIONS

Radiotherapy after 3 cycles or fewer cycles of chemotherapy does not bring significant benefits for RR of patients with LS-SCLC, but it could significantly prolong their PFS without increase in adverse reactions.

[The effect and mechanism of vinorelbine on cisplatin resistance of human lung cancer cell line A549/DDP]

背景与目的

肺癌细胞耐药已经成为肺癌化疗的主要困难之一，异长春花碱被认为可有效抑制肺癌细胞的增殖和转移。本研究旨在探讨异长春花碱对人肺癌A549/DDP细胞顺铂耐受性的逆转作用及机制。

方法

1 μmol/L和5 μmol/L异长春花碱作用A549/DDP细胞后，应用MTS法检测肿瘤细胞顺铂敏感性的变化，应用流式细胞术检测肿瘤细胞凋亡率变化，肿瘤细胞对Rh-123摄入量的变化，Western blot法检测MDR1、Bcl-2、survivin、caspase-3/8和PTEN蛋白表达以及Akt的磷酸化水平的变化，real-time PCR检测MDR1、Bcl-2、survivin和PTEN的mRNA表达，用报告基因系统检测NF-κB、Twist和Snail的转录活性。

结果

1 μmol/L和5 μmol/L异长春花碱作用A549/DDP细胞后，肿瘤细胞对顺铂的敏感性分别提高了1.91倍和2.54倍，肿瘤细胞对Rh-123的摄入量提高了1.93倍和2.95倍，细胞凋亡增加了2.25倍和3.82倍，MDR1、Bcl-2、survivin蛋白表达和Akt磷酸化水平下调，caspase-3/8和PTEN蛋白表达上调，MDR1的mRNA表达下调43.5%和25.8%，Bcl-2的mRNA表达下调57.3%和34.1%，survivin的mRNA表达下调37.6%和12.4%，PTEN表达上调183.4%和154.2%，NF-κB转录活性下降53.2%和34.5%，Twist转录活性下降61.4%和33.5%，Snail转录活性下降57.8%和18.7%。

结论

异长春花碱可提高肿瘤细胞A549/DDP对顺铂的敏感性，其机制可能与调节PTEN/AKT/NF-κB信号路径活性，进而下调耐药基因表达，上调促凋亡基因表达有关。

MyD88 expression is associated with paclitaxel resistance in lung cancer A549 cells

The purpose of the present study was to investigate the relationship between myeloid differentiation primary response gene 88 (MyD88) expression and the resistance to paclitaxel of A549 lung cancer cells. In order to achieve MyD88 gene overexpression or knockdown in the A549 cell line, the cells were infected with lentivirus carrying MyD88 gene or shRNA to MyD88. MyD88 mRNA and protein expression was measured by RT-qPCR, immunohistochemistry and western blotting after infection for confirmation. Cell prolife-ration was detected by the WST-1 assay. Flow cytometry was used to measure the cell cycle and apoptosis. The transwell migration assay was used to observe the change of migration of transfected cells. The results showed that the overexpression of MyD88 increased the resistance of lung cancer A549 cells to paclitaxel, while the suppression of MyD88 increased the sensitivity of A549 lung cancer cells to paclitaxel. Following the paclitaxel treatment, a decreased apoptosis and G2 phase ratio, an increased cell migration ratio, and an increased production of IL-8 were found in MyD88‑overexpressed A549 cells. The western blot analysis revealed that Myd88 overexpression resulted in an increased level of Bcl-2 but a decreased level of Bax in A549 cells. These findings suggested that the expression level of MyD88 is closely associated with paclitaxel resistance in A549 lung cancer cells. Thus, the downregulation of MyD88 in A549 cells increased its sensitivity to paclitaxel treatment, whereas the upregulation of MyD88 substantiates its paclitaxel resistance.

Effect and mechanism of Src tyrosine kinase inhibitor sunitinib on the drug-resistance reversal of human A549/DDP cisplatin-resistant lung cancer cell line

The development of tumor cell drug resistance is the primary reason for treatment failure in lung cancer chemotherapy. Therefore, overcoming multidrug resistance is currently an urgent issue to be addressed in lung cancer treatment. Sunitinib is a tyrosine kinase inhibitor with confirmed inhibitory effects on tumor growth and metastasis; however, the effects of sunitinib and mechanisms of action in lung cancer multidrug resistance are yet to be determined. The present study was designed to examine the effects of sunitinib and the mechanisms underlying lung cancer multidrug resistance. It was observed that sunitinib was able to improve the sensitivity of A549/DDP lung cancer cells to cisplatin, enhance tumor apoptosis, arrest the cell cycle in G0/G1 phase, upregulate intracellular Rh-123 content, downregulate the expression of P-glycoprotein, multidrug resistance protein 1, multidrug resistance-associated protein 1, lung resistance protein, glutathione-S-transferase, ERCC1, survivin and Bcl-2 in tumor cells, phosphorylation of AKT and extracellular signal-regulated kinase (ERK), glutathione activity, and transcriptional activity of nuclear factor-κB, Twist, Snail and AP-1. The results demonstrated that sunitinib was able to reverse the multidrug resistance of A549/DDP lung cancer cells, which was possibly associated with the downregulation of multidrug resistance-associated gene expression and the inhibition of AKT and ERK phosphorylation.

Surfactant-based drug delivery systems for treating drug-resistant lung cancer

Among all cancers, lung cancer is the major cause of deaths. Lung cancer can be categorized into two classes for prognostic and treatment purposes: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Both categories of cancer are resistant to certain drugs. Various mechanisms behind drug resistance are over-expression of superficial membrane proteins [glycoprotein (P-gp)], lung resistance-associated proteins, aberration of the intracellular enzyme system, enhancement of the cell repair system and deregulation of cell apoptosis. Structure-performance relationships and chemical compatibility are consequently major fundamentals in surfactant-based formulations, with the intention that a great deal investigation is committed to this region. With the purpose to understand the potential of P-gp in transportation of anti-tumor drugs to cancer cells with much effectiveness and specificity, several surfactant-based delivery systems have been developed which may include microspheres, nanosized drug carriers (nanoparticles, nanoemulsions, stealth liposomes, nanogels, polymer-drug conjugates), novel powders, hydrogels and mixed micellar systems intended for systemic and/or localized delivery.

Enhanced activity of doxorubicin in drug resistant A549 tumor cells by encapsulation of P-glycoprotein inhibitor in PLGA-based nanovectors

Effective chemotherapy remains an important issue in the treatment of drug resistant cancer. The aim of the present study was to establish novel polymeric nanoparticles composed of the antitumor drug, doxorubicin (DOX), and an inhibitor of the drug efflux pump-associated protein, P-glycoprotein (P-gp), in order to overcome drug resistance in tumor cells. Poly(D,L-lactide-co-glycolide) (PLGA), DOX-loaded PLGA (PLGA-DOX), P-gp inhibitor (cyclosporin A; CsA)-coated PLGA (PLGA-CsA) and DOX and CsA co-loaded PLGA (PLGA-DOX-CsA) nanoparticles were prepared using solvent evaporation. The size distribution, ζ potential and electron microscopy observations of the nanoparticles were characterized. Accumulation and efflux assays were performed using confocal and fluorescence-activated cell sorting (FACS), and the pump activity of P-gp was detected through FACS. The uptake of the nanoparticles and the viability of Taxol-resistant A549 cells treated with various nanoparticles were analyzed via FACS in vitro. Furthermore, the tumor growth and survival rates of A549-Taxol-bearing mice were monitored in vivo. Prepared particles were nanosized and the efflux rates of PLGA-DOX and PLGA-DOX-CsA were significantly decreased compared with the free DOX. Drug efflux pump activity was effectively inhibited by the PLGA-CsA and PLGA-DOX-CsA groups compared with the PLGA, PLGA-DOX and free DOX groups. Cell viability results demonstrated that PLGA-DOX and PLGA-DOX-CsA induced the increased death of A549-Taxol cells. In vivo tumor models demonstrated that PLGA-DOX and PLGA-DOX-CsA markedly inhibited the tumor growth and improved the survival rate of A549-Taxol-bearing mice. Antitumor drug and drug efflux pump inhibitor co-loaded nanoparticles offer advantages to overcome the drug resistance of tumors and highlight new therapeutic strategies to control drug resistant tumors.

A combination of two electrophoretical approaches for detailed proteome-based characterization of SCLC subtypes

CONTEXT

Small cell lung cancers (SCLC) are heterogeneous and tumours differ in growth characteristics and treatment resistance.

OBJECTIVE

To get insight into the underlying protein profiles responsible for this heterogeneity, two subtypes of SCLC cells mutually differing in chemo resistance properties and growth characteristics are analysed.

MATERIALS AND METHODS

Two different electrophoresis approaches in combination with mass spectrometry were used to detect differences between the SCLC cell lines GLC1 and GLC1M13: IEF/SDS-PAGE as well as cetyltrimethylammonium bromide (CTAB)-SDS-PAGE.

RESULTS

Altogether 60 non redundant differentially expressed proteins were found of which 5 were verified by Western Blot analysis.

DISCUSSION

Most of these proteins identified are involved in processes of tumour progression. Therefore, these proteins are interesting candidates for further functional analysis.

CONCLUSION

Additional CTAB-SDS page is a complementary method to IEF-SDS page revealing a complete new subset of proteins differentially expressed between GLC1 and GLC1 M13 cells SCLC subtypes.

Erlotinib resistance in lung cancer: current progress and future perspectives

Lung cancer is the most common cancer in the world. Despite modern advancements in surgeries, chemotherapies, and radiotherapies over the past few years, lung cancer still remains a very difficult disease to treat. This has left the death rate from lung cancer victims largely unchanged throughout the past few decades. A key cause for the high mortality rate is the drug resistance that builds up for patients being currently treated with the chemotherapeutic agents. Although certain chemotherapeutic agents may initially effectively treat lung cancer patients, there is a high probability that there will be a reoccurrence of the cancer after the patient develops resistance to the drug. Erlotinib, the epidermal growth factor receptor (EGFR)-targeting tyrosine kinase inhibitor, has been approved for localized as well as metastatic non-small cell lung cancer where it seems to be more effective in patients with EGFR mutations. Resistance to erlotinib is a common observation in clinics and this review details our current knowledge on the subject. We discuss the causes of such resistance as well as innovative research to overcome it. Evidently, new chemotherapy strategies are desperately needed in order to better treat lung cancer patients. Current research is investigating alternative treatment plans to enhance the chemotherapy that is already offered. Better insight into the molecular mechanisms behind combination therapy pathways and even single molecular pathways may help improve the efficacy of the current treatment options.