Formation of Tumorspheres with Increased Stemness without External Mitogens in a Lung Cancer Model

Yakisich, Juan Sebastián; Azad, Neelam; Venkatadri, Rajkumar; Kulkarni, Yogesh; Wright, Clayton; Kaushik, Vivek; Iyer, Anand Krishnan V.

doi:10.1155/2016/5603135

Cited by 18 publications

(42 citation statements)

References 37 publications

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“…In cancer cells, Sox2 antagonizes the Hippo pathway and promote stemness (Basu‐Roy et al, ). Sox2 is a frequently amplified gene in small‐cell lung cancer and we previously reported elevated levels of Sox2 in H460 LTs (Yakisich et al, ). In our study, the expression of the transcription factor Oct4, also known as POU5F1 (POU domain, class 5), was lower in PPSS cells compared to cells growing under RCCs (Fig.…”

Section: Resultsmentioning

confidence: 90%

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Chemoresistance of Lung and Breast Cancer Cells Growing Under Prolonged Periods of Serum Starvation

Yakisich

Venkatadri

Azad

et al. 2017

Journal Cellular Physiology

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The efficacy of chemotherapy is hindered by both tumor heterogeneity and acquired or intrinsic multi-drug resistance caused by the contribution of multidrug resistance proteins and stemness-associated prosurvival markers. Therefore, targeting multi-drug resistant cells would be much more effective against cancer. In this study, we characterized the chemoresistance properties of adherent (anchorage-dependent) lung H460 and breast MCF-7 cancer cells growing under prolonged periods of serum starvation (PPSS). We found that under PPSS, both cell lines were highly resistant to Paclitaxel, Colchicine, Hydroxyurea, Obatoclax, Wortmannin, and LY294002. Levels of several proteins associated with increased stemness such as Sox2, MDR1, ABCG2, and Bcl-2 were found to be elevated in H460 cells but not in MCF-7 cells. While pharmacological inhibition of either MDR1, ABCG2, Bcl-2 with Verapamil, Sorafenib, or Obatoclax, respectively decreased the levels of their target proteins under routine culture conditions as expected, such inhibition did not reverse PX resistance in PPSS conditions. Paradoxically, treatment with inhibitors in serum-starved conditions produced an elevation of their respective target proteins. In addition, we found that Digitoxin, an FDA approved drug that decrease the viability of cancer cells growing under PPSS, downregulates the expression of Sox2, MDR1, phospho- AKT, Wnt5a/b, and β-catenin. Our data suggest that PPSS-induced chemoresistance is the result of extensive rewiring of intracellular signaling networks and that multi-resistance can be effectively overcome by simultaneously targeting multiple targets of the rewired network. Furthermore, our PPSS model provides a simple and useful tool to screen drugs for their ability to target multiple pathways of cancer resistance. J. Cell. Physiol. 232: 2033-2043, 2017. © 2016 Wiley Periodicals, Inc.

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Section: Resultsmentioning

confidence: 90%

“…We previously demonstrated that therapeutic levels of Digitoxin (20–50 nM) were able to decrease the viability of cells growing under RCCs, PPSS as well as floating LTs (Yakisich et al, ,). In LTs, Digitoxin (DIG) reduced the expression of Sox2 (Yakisich et al, ).…”

Section: Resultsmentioning

confidence: 99%

Chemoresistance of Lung and Breast Cancer Cells Growing Under Prolonged Periods of Serum Starvation

Yakisich

Venkatadri

Azad

et al. 2017

Journal Cellular Physiology

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“…LTs were generated as previously described (Yakisich et al, ,). Briefly, cells grown in CM (70–80% confluency) were cultured overnight in serum‐free media (SFM, same as CM but without FBS).…”

Section: Methodsmentioning

confidence: 99%

“…We recently designed a novel set of cardenolide analogs that recapitulate the therapeutic benefits of Digitoxin signaling in cancer while overcoming Digitoxin‐associated toxicity, and our preliminary study demonstrated potent anti‐tumorigenic effects against several forms of cancer (Iyer et al, ). We have further characterized the action of cardiac glycosides in exerting tumoristatic effects in multiple models of lung cancer including routine culture, long‐term serum starvation as well as lung tumorspheres (Yakisich et al, ,). This led us to investigate other naturally occurring forms of cardiac glycosides that may similarly exert strong anti‐tumor effects against lung cancer.…”

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confidence: 99%

Anti‐Tumor Effects of Cardiac Glycosides on Human Lung Cancer Cells and Lung Tumorspheres

Kaushik

Yakisich

Azad

et al. 2017

Journal Cellular Physiology

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Lung cancer is a leading cause of cancer-related death in the United States. Although several drugs have been developed that target individual biomarkers, their success has been limited due to intrinsic or acquired resistance for the specific targets of such drugs. A more effective approach is to target multiple pathways that dictate cancer progression. Cardiac glycosides demonstrate such multimodal effects on cancer cell survival, and our aim was to evaluate the effect of two naturally occurring monosaccaridic cardiac glycosides-Convallatoxin and Peruvoside on lung cancer cells. Although both drugs had significant anti-proliferative effects on H460 and Calu-3 lung cancer cells, Convallatoxin demonstrated twofold higher activity as compared to Peruvoside using both viability and colony forming assays, suggesting a role for the aglycone region in dictating drug potency. The tumor suppressor p53 was found to be important for action of both drugs-p53-underexpressing cells were less sensitive as compared to p53-positive H460 cells. Further, assessment of p53-underexpressing H460 cells showed that drugs were able to arrest cells in the G0/G1 phase of the cell cycle in a dose-dependent manner. Both drugs significantly inhibited migration and invasion of cancer cells and decreased the viability of floating tumorspheres. An assessment of intracellular pathways indicated that both drugs were able to modulate proteins that are involved in apoptosis, autophagy, cell cycle, proliferation, and EMT. Our data suggest, a promising role for cardiac glycosides in lung cancer treatment, and provides impetus for further investigation of the anti-cancer potential of this class of drugs. J. Cell. Physiol. 232: 2497-2507, 2017. © 2016 Wiley Periodicals, Inc.

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“…12 For viability assays, LTs were collected in 15-mL Falcon tubes, centrifuged at 700 r/min × 3 min and resuspended in fresh SFM. In order to plate the same number of cells, this cell suspension was split in 1-mL aliquots.…”

Section: Tumorsphere Assaymentioning

confidence: 99%

Nigericin decreases the viability of multidrug-resistant cancer cells and lung tumorspheres and potentiates the effects of cardiac glycosides

et al. 2017

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Multiple factors including tumor heterogeneity and intrinsic or acquired resistance have been associated with drug resistance in lung cancer. Increased stemness and the plasticity of cancer cells have been identified as important mechanisms of resistance; therefore, treatments targeting cancer cells independent of stemness phenotype would be much more effective in treating lung cancer. In this article, we have characterized the anticancer effects of the antibiotic Nigericin in cells displaying varying degrees of stemness and resistance to anticancer drugs, arising from (1) routine culture conditions, (2) prolonged periods of serum starvation. These cells are highly resistant to conventional anticancer drugs such as Paclitaxel, Hydroxyurea, Colchicine, Obatoclax, Wortmannin, and LY294002, and the multidrug-resistant phenotype of cells growing under prolonged periods of serum starvation is likely the result of extensive rewiring of signaling pathways, and (3) lung tumorspheres that are enriched for cancer stem-like cells. We found that Nigericin potently inhibited the viability of cells growing under routine culture conditions, prolonged periods of serum starvation, and lung tumorspheres. In addition, we found that Nigericin downregulated the expression of key proteins in the Wnt canonical signaling pathway such as LRP6, Wnt5a/b, and β-catenin, but promotes β-catenin translocation into the nucleus. The antitumor effects of Nigericin were potentiated by the Wnt activator HLY78 and by therapeutic levels of the US Food and Drug Administration-approved drug Digitoxin and its novel synthetic analog MonoD. We believe that Nigericin may be used in a co-therapy model in combination with other novel chemotherapeutic agents in order to achieve potent inhibition of cancers that display varying degrees of stemness, potentially leading to sustained anticancer effects.

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Formation of Tumorspheres with Increased Stemness without External Mitogens in a Lung Cancer Model

Cited by 18 publications

References 37 publications

Chemoresistance of Lung and Breast Cancer Cells Growing Under Prolonged Periods of Serum Starvation

Chemoresistance of Lung and Breast Cancer Cells Growing Under Prolonged Periods of Serum Starvation

Anti‐Tumor Effects of Cardiac Glycosides on Human Lung Cancer Cells and Lung Tumorspheres

Nigericin decreases the viability of multidrug-resistant cancer cells and lung tumorspheres and potentiates the effects of cardiac glycosides

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