Ciprofloxacin mediates cancer stem cell phenotypes in lung cancer cells through caveolin-1-dependent mechanism

Advancements in Synthetic Strategies and Biological Effects of Ciprofloxacin Derivatives: A Review

Ciprofloxacin is a widely used antibiotic in the fluoroquinolone class. It is widely acknowledged by various researchers worldwide, and it has been documented to have a broad range of other pharmacological activities, such as anticancer, antiviral, antimalarial activities, etc. Researchers have been exploring the synthesis of ciprofloxacin derivatives with enhanced biological activities or tailored capability to target specific pathogens. The various biological activities of some of the most potent and promising ciprofloxacin derivatives, as well as the synthetic strategies used to develop them, are thoroughly reviewed in this paper. Modification of ciprofloxacin via 4-oxo-3-carboxylic acid resulted in derivatives with reduced efficacy against bacterial strains. Hybrid molecules containing ciprofloxacin scaffolds displayed promising biological effects. The current review paper provides reported findings on the development of novel ciprofloxacin-based molecules with enhanced potency and intended therapeutic activities which will be of great interest to medicinal chemists.

Shrimp Lipids Inhibit Migration, Epithelial-Mesenchymal Transition, and Cancer Stem Cells via Akt/mTOR/c-Myc Pathway Suppression

Shrimp is a rich source of bioactive molecules that provide health benefits. However, the high cholesterol content in shrimp oil may pose a risk. We utilized the cholesterol elimination method to obtain cholesterol-free shrimp lipids (CLs) and investigated their anticancer potential, focusing on cancer stem cells (CSCs) and epithelial-to-mesenchymal transition (EMT). Our study focused on CSCs and EMT, as these factors are known to contribute to cancer metastasis. The results showed that treatment with CLs at doses ranging from 0 to 500 µg/mL significantly suppressed the cell migration ability of human lung cancer (H460 and H292) cells, indicating its potential to inhibit cancer metastasis. The CLs at such concentrations did not cause cytotoxicity to normal human keratinocytes. Additionally, CL treatment was found to significantly reduce the levels of Snail, Slug, and Vimentin, which are markers of EMT. Furthermore, we investigated the effect of CLs on CSC-like phenotypes and found that CLs could significantly suppress the formation of a three-dimensional (3D) tumor spheroid in lung cancer cells. Furthermore, CLs induced apoptosis in the CSC-rich population and significantly depleted the levels of CSC markers CD133, CD44, and Sox2. A mechanistic investigation demonstrated that exposing lung cancer cells to CLs downregulated the phosphorylation of Akt and mTOR, as well as c-Myc expression. Based on these findings, we believe that CLs may have beneficial effects on health as they potentially suppress EMT and CSCs, as well as the cancer-potentiating pathway of Akt/mTOR/c-Myc.

Targeting Alpha7 Nicotinic Acetylcholine Receptors in Lung Cancer: Insights, Challenges, and Therapeutic Strategies

Alpha7 nicotinic acetylcholine receptor (α7 nAChR) is an ion-gated calcium channel that plays a significant role in various aspects of cancer pathogenesis, particularly in lung cancer. Preclinical studies have elucidated the molecular mechanism underlying α7 nAChR-associated lung cancer proliferation, chemotherapy resistance, and metastasis. Understanding and targeting this mechanism are crucial for developing therapeutic interventions aimed at disrupting α7 nAChR-mediated cancer progression and improving treatment outcomes. Drug research and discovery have determined natural compounds and synthesized chemical antagonists that specifically target α7 nAChR. However, approved α7 nAChR antagonists for clinical use are lacking, primarily due to challenges related to achieving the desired selectivity, efficacy, and safety profiles required for effective therapeutic intervention. This comprehensive review provided insights into the molecular mechanisms associated with α7 nAChR and its role in cancer progression, particularly in lung cancer. Furthermore, it presents an update on recent evidence about α7 nAChR antagonists and addresses the challenges encountered in drug research and discovery in this field.

The effect of ciprofloxacin on doxorubicin cytotoxic activity in the acquired resistance to doxorubicin in DU145 prostate carcinoma cells

The present study aimed to assess the influence of ciprofloxacin (CIP) against the doxorubicin (DOX)-resistant androgen-independent prostate cancer DU145 cells. The DOX-resistant DU145 (DU145/DOX20) cells were established by exposing DU145 cells to the increasing concentrations of DOX. The antiproliferative effect of CIP was examined through employing MTT, colony formation, and 3D culture assays. DU145/DOX20 cells exhibited a twofold higher IC₅₀ value for DOX, an increased ABCB1 transporter activity, and some morphological changes accompanied by a decrease in spheroid size, adhesive and migration potential compared to DU145 cells. CIP (5 and 25 µg mL^-1) resulted in a higher reduction in the viability of DU145/DOX20 cells than in DU145 cells. DU145/DOX20 cells were more resistant to CIP in 3D culture compared to the 2D one. No spheroid formation was observed for DU145/DOX20 cells treated with DOX and CIP combination. CIP and DOX, alone or in combination, significantly reduced the growth of DU145 spheroids. CIP in combination with 20 nM DOX prevented the colony formation of DU145 cells. The clonogenicity of DU145/DOX20 cells could not be estimated due to their low adhesive potential. CIP alone caused a significant reduction in the migration of DU145 cells and resulted in a more severe decrease in the wound closure ability of DOX-exposed ones. We identified that CIP enhanced DOX sensitivity in DU145 and DU145/DOX20 cells. This study suggested the co-delivery of low concentrations of CIP and DOX may be a promising strategy in treating the DOX-resistant and -sensitive hormone-refractory prostate cancer.

Caveolin1: its roles in normal and cancer stem cells

PURPOSE

Stem cells are characterized by the capability of self-renewal and multi-differentiation. Normal stem cells, which are important for tissue repair and tissue regeneration, can be divided into embryonic stem cells (ESCs) and somatic stem cells (SSCs) depending on their origin. As a subpopulation of cells within cancer, cancer stem cells (CSCs) are at the root of therapeutic resistance. Tumor-initiating cells (TICs) are necessary for tumor initiation. Caveolin1 (Cav1), a membrane protein located at the caveolae, participates in cell lipid transport, cell migration, cell proliferation, and cell signal transduction. The purpose of this review was to explore the relationship between Cav1 and stem cells.

RESULTS

In ESCs, Cav1 is beneficial for self-renewal, proliferation, and migration. In SSCs, Cav1 exhibits positive or/and negative effects on stem cell self-renewal, differentiation, proliferation, migration, and angiogenic capacity. Cav1 deficiency impairs normal stem cell-based tissue repair. In CSCs, Cav1 inhibits or/and promotes CSC self-renewal, differentiation, invasion, migration, tumorigenicity ability, and CSC formation. And suppressing Cav1 promotes chemo-sensitivity in CSCs and TICs.

CONCLUSION

Cav1 shows dual roles in stem cell biology. Targeting the Cav1-stem cell axis would be a new way for tissue repair and cancer drug resistance.

Multi-scale supervised clustering-based feature selection for tumor classification and identification of biomarkers and targets on genomic data

Background

The small number of samples and the curse of dimensionality hamper the better application of deep learning techniques for disease classification. Additionally, the performance of clustering-based feature selection algorithms is still far from being satisfactory due to their limitation in using unsupervised learning methods. To enhance interpretability and overcome this problem, we developed a novel feature selection algorithm. In the meantime, complex genomic data brought great challenges for the identification of biomarkers and therapeutic targets. The current some feature selection methods have the problem of low sensitivity and specificity in this field.

Results

In this article, we designed a multi-scale clustering-based feature selection algorithm named MCBFS which simultaneously performs feature selection and model learning for genomic data analysis. The experimental results demonstrated that MCBFS is robust and effective by comparing it with seven benchmark and six state-of-the-art supervised methods on eight data sets. The visualization results and the statistical test showed that MCBFS can capture the informative genes and improve the interpretability and visualization of tumor gene expression and single-cell sequencing data. Additionally, we developed a general framework named McbfsNW using gene expression data and protein interaction data to identify robust biomarkers and therapeutic targets for diagnosis and therapy of diseases. The framework incorporates the MCBFS algorithm, network recognition ensemble algorithm and feature selection wrapper. McbfsNW has been applied to the lung adenocarcinoma (LUAD) data sets. The preliminary results demonstrated that higher prediction results can be attained by identified biomarkers on the independent LUAD data set, and we also structured a drug-target network which may be good for LUAD therapy.

Conclusions

The proposed novel feature selection method is robust and effective for gene selection, classification, and visualization. The framework McbfsNW is practical and helpful for the identification of biomarkers and targets on genomic data. It is believed that the same methods and principles are extensible and applicable to other different kinds of data sets.

The regulatory pathways leading to stem-like cells underlie prostate cancer progression

Prostate cancer (PCa) is the most common cause of malignancy in males and the third leading cause of cancer mortality in the United States. The standard care for primary PCa with local invasive disease mainly is surgery and radiation. For patients with distant metastases, androgen deprivation therapy (ADT) is a gold standard. Regardless of a favorable outcome of ADT, patients inevitably relapse to an end-stage castration-resistant prostate cancer (CRPC) leading to mortality. Therefore, revealing the mechanism and identifying cellular components driving aggressive PCa is critical for prognosis and therapeutic intervention. Cancer stem cell (CSC) phenotypes characterized as poor differentiation, cancer initiation with self-renewal capabilities, and therapeutic resistance are proposed to contribute to the onset of CRPC. In this review, we discuss the role of CSC in CRPC with the evidence of CSC phenotypes and the possible underlying mechanisms.

Multifaceted Roles of Caveolin-1 in Lung Cancer: A New Investigation Focused on Tumor Occurrence, Development and Therapy

Lung cancer is one of the most common and malignant cancers with extremely high morbidity and mortality in both males and females. Although traditional lung cancer treatments are fast progressing, there are still limitations. Caveolin-1 (Cav-1), a main component of caveolae, participates in multiple cellular events such as immune responses, endocytosis, membrane trafficking, cellular signaling and cancer progression. It has been found tightly associated with lung cancer cell proliferation, migration, apoptosis resistance and drug resistance. In addition to this, multiple bioactive molecules have been confirmed to target Cav-1 to carry on their anti-tumor functions in lung cancers. Cav-1 can also be a predictor for lung cancer patients’ prognosis. In this review, we have summarized the valuable research on Cav-1 and lung cancer in recent years and discussed the multifaceted roles of Cav-1 on lung cancer occurrence, development and therapy, hoping to provide new insights into lung cancer treatment.

Differential Expression And Effects Of Peroxiredoxin-6 On Drug Resistance And Cancer Stem Cell-Like Properties In Non-Small Cell Lung Cancer

Objective

Cancer stem-like cells (CSC) are thought to be involved in the cisplatin resistance of tumors. This study was designed to investigate the effect of PRDX6 on CSCs present in cisplatin-resistant non-small cell lung cancer (NSCLC) tumors.

Materials and methods

CD133+/ABCG2+ H1299 CSCs and A549 CSCs were isolated. The IC₅₀ values for cisplatin in treatment of CSCs were detected using the CCK8 assay. Then the isolated cells were identified using CD133. Wnt/β-catenin expression was evaluated by Western blot assays. Specimens of tumor and adjacent para-carcinoma tissue were collected from 30 NSCLC patients and examined by immunohistochemistry (IHC), qRT-PCR, and Western blotting to determine and compare their levels of PRDX6 and CD133 expression. Finally, siRNA-mediated silencing of PRDX6 was employed with both types of CSCs to determine the impact of PRDX6 on CD133 enrichment by flow cytometry, cell viability, and sphere formation ability.

Results

High levels of PRDX6 and CD133 expression were detected in samples of tumor tissue from NSCLC patients, and expression of PRDX6 and CD13 presented a positive relationship. Increasing levels of cisplatin resistance and upregulated levels of PRDX6, ABCG2, Wnt, and β-catenin expression were detected in CD133+/ABCG2+ H1299 and A549 CSCs. Transfection with siRNA targeting PRDX6 changed these cellular characteristics by decreasing the levels of PRDX6, ABCG2, Wnt, and β-catenin expression. We further demonstrated that exogenous silencing of PRDX6 effectively inhibited the sphere formation ability of CSCs and re-sensitized them to cisplatin.

Conclusion

Our results strongly suggest that PRDX6 promotes cisplatin resistance in human lung cancer cells by promoting the stem-like properties of cancer cells. Our findings also suggest PRDX6 as a target for treating cisplatin resistant NSCLC.

The paracrine induction of prostate cancer progression by caveolin-1

A subpopulation of cancer stem cells (CSCs) plays a critical role of cancer progression, recurrence, and therapeutic resistance. Many studies have indicated that castration-resistant prostate cancer (CRPC) is associated with stem cell phenotypes, which could further promote neuroendocrine transdifferentiation. Although only a small subset of genetically pre-programmed cells in each organ has stem cell capability, CSCs appear to be inducible among a heterogeneous cancer cell population. However, the inductive mechanism(s) leading to the emergence of these CSCs are not fully understood in CRPC. Tumor cells actively produce, release, and utilize exosomes to promote cancer development and metastasis, cancer immune evasion as well as chemotherapeutic resistance; the impact of tumor-derived exosomes (TDE) and its cargo on prostate cancer (PCa) development is still unclear. In this study, we demonstrate that the presence of Cav-1 in TDE acts as a potent driver to induce CSC phenotypes and epithelial-mesenchymal transition in PCa undergoing neuroendocrine differentiation through NFκB signaling pathway. Furthermore, Cav-1 in mCRPC-derived exosomes is capable of inducing radio- and chemo-resistance in recipient cells. Collectively, these data support Cav-1 as a critical driver for mCRPC progression.

Concentration-Dependent Dual Effects of Ciprofloxacin on SB-590885-Resistant BRAFV600E A375 Melanoma Cells

BRAF inhibitors (BRAFi) have been applied to treat melanoma harboring V600E mutations. Several studies showed that BRAFi-resistant melanomas are dependent on mitochondrial biogenesis. Therefore, the present study aimed to investigate the influence of ciprofloxacin (CIP), a mitochondria-targeting antibiotic, on SB-590885-resistant BRAF^V600E A375 melanoma (A375/SB) cells. The cytotoxicity activity of CIP and SB-590885, a potent and specific BRAFi, on A375 and A375/SB cells was evaluated by MTT, colony formation, migration, and spheroid formation assays. Moreover, SB-590885-induced cell death in A375 cells was analyzed. SB-590885 showed time- and concentration-dependent cytotoxic effects on A375 cells. Twenty-five μg/mL CIP decreased the cell viability of A375 and A375/SB cells in a time-dependent manner. This concentration of CIP markedly decreased clonogenicity in both cells and caused a reduction in the growth of A375/SB spheroids. The cytotoxicity of 5 μg/mL CIP on A375/SB cells was less than that of A375 cells. The colony formation and migration ability of A375/SB cells was increased in the presence of 5 μg/mL CIP. Ten μM SB-590885 induced a massive vacuolization in A375 cells. Cell death assays suggested a simultaneous activation of autophagy, paraptosis, apoptosis, and necrosis. For the first time, this study reveals that CIP at the maximum concentration in serum (5 μg/mL) can enhance the colony formation and migration abilities in BRAFi-resistant melanoma cells, while it has cytotoxic activity against these cells at a higher concentration than serum level. This study suggests that CIP may promote aggressive growth properties in BRAFi-resistant melanomas, at a concentration present in serum.

Ti0.8O2 Nanosheets Inhibit Lung Cancer Stem Cells by Inducing Production of Superoxide Anion

Recent research into the cancer stem cell (CSC) concept has driven progress in the understanding of cancer biology and has revealed promising CSC-specific targets for drug discovery efforts. As malignancies of lung cancer have been shown to be strongly associated with activities of CSCs, we examined the effects of Ti0.8O2 nanosheets on these cells. Here we show that the nanosheets target lung CSCs but not normal primary dermal papilla (DP) stem cells. Whereas Ti0.8O2 caused a dramatic apoptosis along with a decrease in CSC phenotypes, in primary human DP cells such effects of nanosheets have been minimal. Nanosheets reduced the ability of lung cancer cells to generate three-dimensional tumor spheroids, lung CSC markers (CD133 and ALDH1A1), and CSC transcription factors (Nanog and Oct-4). Ti0.8O2 nanosheets reduced CSC signaling through mechanisms involving suppression of protein kinase B (AKT) and Notch-1 pathways. In addition, the nanosheets inhibited the migration and invasive activities of lung cancer cells and reduced epithelial-to-mesenchymal transition (EMT) markers as N-cadherin, vimentin, and Slug, as well as metastasis-related integrins (integrin-αv and integrin-β1). Importantly, we found that the selectivity of the Ti0.8O2 nanosheets in targeting cancer cells was mediated by induction of cellular superoxide anion in cancerous but not normal cells. Inhibition of nanosheet-induced superoxide anion restored the suppression of CSC and EMT in cancer cells. These findings demonstrate a promising distinctive effect of Ti0.8O2 nanosheets on lung CSC that may lead to opportunities to use such a nanomaterial in cancer therapy.

Repositioning of fluoroquinolones from antibiotic to anti-cancer agents: An underestimated truth

Increasing development costs and higher failure rate in clinical trials has reduced the repertoire of newer drugs in the market for clinical use. The most appropriate approach to end the search for newer drugs is "Repositioning", as it requires less time and money to explore new indication of existing drug or failed drug. In the past, several drugs have been repositioned for different indication but the full potential remains unharnessed. With rise in cancer prevalence and treatment costs, it is imperative to search for newer drugs and the use of repositioning approach may help us. Fluoroquinolones has been used as antibiotics for over four decades now, but recent research highlighted their use as pharmacological compounds with multifaceted implication. Repositioning of fluoroquinolones into anti-cancer molecule seems to be a highly plausible option owing to their profound immunomodulatory, pro-apoptotic, anti-proliferative and anti-metastatic potential. The present review provides a comprehensive account of the recent and past explorations pertaining to the anti-cancer activity of fluoroquinolones and also discusses the various approaches that are being considered to remodel them for the treatment of cancer.

Effect of Ciprofloxacin on Susceptibility to Aortic Dissection and Rupture in Mice

Importance

Fluoroquinolones are among the most commonly prescribed antibiotics. Recent clinical studies indicated an association between fluoroquinolone use and increased risk of aortic aneurysm and dissection (AAD). This alarming association has raised concern, especially in patients with AAD with risk of rupture and in individuals at risk for developing AAD.

Objective

To examine the effect of ciprofloxacin on AAD development in mice.

Design, Setting, and Participants

In a mouse model of moderate, sporadic AAD, 4-week-old male and female C57BL/6J mice were challenged with a high-fat diet and low-dose angiotensin infusion (1000 ng/min/kg). Control unchallenged mice were fed a normal diet and infused with saline. After randomization, challenged and unchallenged mice received ciprofloxacin (100 mg/kg/d) or vehicle through daily gavage during angiotensin or saline infusion. Aortic aneurysm and dissection development and aortic destruction were compared between mice. The direct effects of ciprofloxacin on aortic smooth muscle cells were examined in cultured cells.

Results

No notable aortic destruction was observed in unchallenged mice that received ciprofloxacin alone. Aortic challenge induced moderate aortic destruction with development of AAD in 17 of 38 mice (45%) and severe AAD in 9 (24%) but no rupture or death. However, challenged mice that received ciprofloxacin had severe aortic destruction and a significantly increased incidence of AAD (38 of 48 [79%]; P = .001; χ2 = 10.9), severe AAD (32 of 48 [67%]; P < .001; χ2 = 15.7), and rupture and premature death (7 of 48 [15%]; P = .01; χ2 = 6.0). The increased AAD incidence was observed in different aortic segments and was similar between male and female mice. Compared with aortic tissues from challenged control mice, those from challenged mice that received ciprofloxacin showed decreased expression of lysyl oxidase, an enzyme that is critical in the assembly and stabilization of elastic fibers and collagen. These aortas also showed increased matrix metalloproteinase levels and activity, elastic fiber fragmentation, and aortic cell injury. In cultured smooth muscle cells, ciprofloxacin treatment significantly reduced lysyl oxidase expression and activity, increased matrix metalloproteinase expression and activity, suppressed cell proliferation, and induced cell death. Furthermore, ciprofloxacin-a DNA topoisomerase inhibitor-caused nuclear and mitochondrial DNA damage and the release of DNA into the cytosol, subsequently inducing mitochondrial dysfunction, reactive oxygen species production, and activation of the cytosolic DNA sensor STING, which we further showed was involved in the suppression of lysyl oxidase expression and induction of matrix metalloproteinase expression.

Conclusions and Relevance

Ciprofloxacin increases susceptibility to aortic dissection and rupture in a mouse model of moderate, sporadic AAD. Ciprofloxacin should be used with caution in patients with aortic dilatation, as well as in those at high risk for AAD.

MiR-2861 Behaves as a Biomarker of Lung Cancer Stem Cells and Regulates the HDAC5-ERK System Genes

Cancer stem cells (CSCs) are responsible for cancer initiating, recurrence, and drug resistance. Discovery of novel biomarkers for CSCs is helpful for early diagnosis and prognosis. Lung cancer stem cells (LCSCs) were closely related to the occurrence and development of lung cancer. In our study, the important role of miR-2861 in maintaining the stemness of LCSCs was investigated. The LCSC differentiation model was established through introducing serum into the medium of H460 spheres. miR-2861 expression was significantly higher in LCSCs no matter compared to the differentiation cells or normal cells. HDAC5 expression was positively correlated with miR-2861 in LCSCs, and knockdown of miR-2861 decreased the expression of HDAC5, which implied that HDAC5 may be involved in the differentiation of LCSCs mediated by miR-2861. The role of HDAC5 in the regulation of LCSC differentiation was further verified by the inhibitory effect of LMK-235 on the phosphorylation of ERK1/2, which was recognized as the regulator of CSC differentiation. Our study provided a better understanding of miR-2861 and HDAC5 axis in maintaining the stemness of LCSCs and laid a foundation for molecular targeted therapy.

Cancer Stem Cell-Suppressing Activity of Chrysotoxine, a Bibenzyl from Dendrobium pulchellum

Cancer stem cells (CSCs) have been recognized as rare populations driving cancer progression, metastasis, and drug resistance in leading cancers. Attempts have been made toward identifying compounds that specifically target these CSCs. Therefore, investigations of novel therapeutic strategies for CSC targeting are required. The cytotoxic effects of chrysotoxine on human non-small cell lung cancer-derived H460 and H23 cells were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The effects of chrysotoxine suppression of CSC-like phenotypes were determined in CSC-rich populations and primary CSCs in three-dimensional (3D) culture and in an extreme limiting dilution assay. Expression of CSC markers and associated proteins was determined by Western blot analyse and flow cytometry. We have reported herein the CSC-suppressing activity of chrysotoxine, a bibenzyl compound isolated from Dendrobium pulchellum We have shown, to our knowledge for the first time, that chrysotoxine dramatically suppresses CSC-like phenotypes of H460 and H23 cells. Treatment with chrysotoxine significantly reduced the viability of 3D CSC-rich populations and concomitantly decreased known CSC markers. Chrysotoxine suppressed CSC phenotypes through downregulation of Src/protein kinase B (Akt) signaling. Active (phosphorylated Y416) Src was shown to regulate cancer stemness, since ectopic overexpression of Src strongly activated Akt and subsequently enhanced pluripotency transcription factor SRY (sex-determining region Y)-box 2 (Sox2)- mediating CSC phenotypes, whereas the short hairpin RNA of Src and an Src inhibitor (dasatinib) suppressed Akt, Sox2, and CSC properties. Importantly, chrysotoxine was shown to suppress active Src/Akt signaling and in turn depleted Sox2-mediated CSCs. Our findings indicate a novel CSC-targeted role of chrysotoxine and its regulation by Src/Akt and Sox2, which may be exploited for cancer treatment.

Clinicopathological significance of caveolin-1 expression by cancer-associated fibroblasts in lung adenocarcinoma

PURPOSE

Caveolin is an essential constituent of caveolae and has many biological functions. Expression of caveolin-1 in cancer cells was reported to be a prognostic marker in several types of cancers, the prognostic significance of its expression in cancer-associated fibroblasts (CAFs) has not been investigated. This study aimed to evaluate the clinicopathological significance of expression by CAFs in lung adenocarcinoma.

METHODS

We examined caveolin-1 expression in both CAFs and cancer cells in stage I invasive lung adenocarcinoma (n = 412) and analyzed the relationship between the expression and clinicopathological factors.

RESULTS

Caveolin-1 expression by CAFs and cancer cells was observed in 12.1% and 7.8% of adenocarcinomas, respectively. Tumors with caveolin-1-positive CAFs had vascular and pleural invasion significantly more frequently than those with caveolin-1-negative CAF (p < 0.05). This was also the cases with tumors with caveolin-1-positive cancer cells (p < 0.01). Caveolin-1 expression by CAFs and that by cancer cells were significant predictors of shorter recurrence-free survival (p < 0.001). Caveolin-1 expression by CAFs and cancer cells was found in 25% and 30% of solid predominant subtype, respectively, but only 9.2% and 2.7% of non-solid predominant subtype, respectively. The frequency of cases with caveolin-1-positive CAFs or cancer cells was significantly higher in the solid predominant subtype than in non-solid predominant subtype (p < 0.001).

CONCLUSIONS

Our current results highlight the prognostic importance of caveolin-1 expression by CAFs in stage I lung adenocarcinoma and provide new insights into the biological significance of caveolin-1 in the tumor microenvironment, especially in microenvironment of solid predominant adenocarcinoma.