Targeting Cancer Stem Cells: A Strategy for Effective Eradication of Cancer.

Cancer stem cells (CSCs) are subpopulations of tumor cells with the ability to self-renew, differentiate, and initiate and maintain tumor growth, and they are considered to be the main drivers of intra- and inter-tumoral heterogeneity. While conventional chemotherapy can eradicate the majority of non-CSC tumor cells, CSCs are often drug-resistant, leading to tumor recurrence and metastasis. The heterogeneity of CSCs is the main challenge in developing CSC-targeting therapy; therefore, we and other investigators have focused on developing novel therapeutic strategies that combine conventional chemotherapy with inhibitors of CSC-regulating pathways. Encouraging preclinical findings have suggested that CSC pathway blockade can indeed enhance cellular sensitivity to non-targeted conventional therapy, and this work has led to several ongoing clinical trials of CSC pathway inhibitors. Our studies in bladder cancer and lung adenocarcinoma have demonstrated a crucial role of YAP1, a transcriptional regulator of genes that promote cell survival and proliferation, in regulating CSC phenotypes. Moreover, using cell lines and patient-derived xenograft models, we showed that inhibition of YAP1 enhances the efficacy of conventional therapies by attenuating CSC stemness features. In this review, we summarize the therapeutic strategies for targeting CSCs in several cancers and discuss the potential and challenges of the approach.

CD24 regulates cancer stem cell (CSC)-like traits and a panel of CSC-related molecules serves as a non-invasive urinary biomarker for the detection of bladder cancer.

BACKGROUND: CD24 is a cornerstone of tumour progression in urothelial carcinoma of the bladder (UCB). However, its contribution to cancer stem cell (CSC)-like traits and the clinical utility of CD24 as a urinary biomarker for cancer detection have not been determined. METHODS: The functional relevance of CD24 was evaluated using in vitro and in vivo approaches. The clinical utility of CSC-related molecules was assessed in urine samples by quantitative RT-PCR. RESULTS: The knockdown of CD24 attenuated cancer stemness properties. The high-CD24-expressing cells, isolated from patient-derived UCB xenograft tumours, exhibited their enhanced stemness properties. CD24 was overexpressed not only in primary tumours but also in urine from UCB subjects. By assessment of 15 candidate CSC-related molecules in urine samples of a training cohort, a panel of three molecules (CD24, CD49f, and NANOG) was selected. The combination of these three molecules yielded a sensitivity and specificity of 81.7% and 74.3%, respectively, in an independent cohort. A combined set of 84 cases and 207 controls provided a sensitivity and specificity of 82% and 76%, respectively. CONCLUSION: CD24 has a crucial role in maintaining the urothelial cancer stem-like traits and a panel of CSC-related molecules has potential as a urinary biomarker for non-invasive UCB detection.

A time for YAP1: Tumorigenesis, immunosuppression and targeted therapy.

YAP1 is one of the most important effectors of the Hippo pathway and has crosstalk with other cancer promoting pathways. YAP1 contributes to cancer development in various ways that include promoting malignant phenotypes, expansion of cancer stem cells and drug resistance of cancer cells. Because pharmacologic or genetic inhibition of YAP1 suppresses tumor progression and increases the drug sensitivity, targeting YAP1 may open a fertile avenue for a novel therapeutic approach in relevant cancers. Recent enormous studies have established the efficacy of immunotherapy, and several immune checkpoint blockades are in clinical use or in the phase of development to treat various cancer types. Immunosuppression in the tumor microenvironment (TME) induced by cancer cells, immune cells and associated stromal cells promotes tumor progression and causes drug resistance. Accumulated evidences of scientific efforts from the last few years suggest that YAP1 influences macrophages, myeloid-derived suppressor cells and regulatory T-cells to facilitate immunosuppressive TME. Although the underlying mechanisms is not clearly discerned, it is evident that YAP1 activating pathways in different cellular components induce immunosuppressive TME. In this review, we summarize the evidences involved in the dual roles of YAP1 in cancer development and immunosuppression in the TME. We also discuss the possibility of YAP1 as a novel therapeutic target.

Arsenic promotes the COX2/PGE2-SOX2 axis to increase the malignant stemness properties of urothelial cells.

Chronic arsenic exposure is associated with the development of urothelial carcinoma of the bladder (UCB). To elucidate the contribution of arsenic exposure to urothelial cancer stem cell (CSC) generation, we established an in vitro stepwise malignant model transformed by chronically exposing human urothelial cells to arsenic. Using this model, we found that chronic arsenic exposure endows urothelial cells with malignant stemness properties including increased expression of stemness-related factors such as SOX2, sphere formation, self-renewal, invasion and chemoresistance. SOX2 was gradually and irreversibly overexpressed in line with acquired sphere-forming and self-renewal abilities. Following gene set enrichment analyses of arsenic-exposed and arsenic-unexposed cells, we found COX2 as an enriched gene for oncogenic signature. Mechanistically, arsenic-induced COX2/PGE2 increases SOX2 expression that eventually promotes malignant stem cell generation and repopulation. In urine samples from 90 subjects exposed to arsenic and 91 control subjects, we found a significant linear correlation between SOX2 and COX2 expression and the potential of SOX2 and COX2 expression as urinary markers to detect subjects exposed to arsenic. Furthermore, the combination marker yielded a high sensitivity for UCB detection in a separate cohort. Finally, our in vitro model exhibits basal-type molecular features and dual inhibition of EGFR and COX2 attenuated stem cell enrichment more efficiently than an EGFR inhibitor alone. In conclusion, the COX2/PGE2-SOX2 axis promotes arsenic-induced malignant stem cell transformation. In addition, our findings indicate the possible use of SOX2 and COX2 expression as urinary markers for the risk stratification and detection of UCB.

A Panel of Novel Detection and Prognostic Methylated DNA Markers in Primary Non-Small Cell Lung Cancer and Serum DNA.

Purpose: To establish a novel panel of cancer-specific methylated genes for cancer detection and prognostic stratification of early-stage non-small cell lung cancer (NSCLC).Experimental Design: Identification of differentially methylated regions (DMR) was performed with bumphunter on "The Cancer Genome Atlas (TCGA)" dataset, and clinical utility was assessed using quantitative methylation-specific PCR assay in multiple sets of primary NSCLC and body fluids that included serum, pleural effusion, and ascites samples.Results: A methylation panel of 6 genes (CDO1, HOXA9, AJAP1, PTGDR, UNCX, and MARCH11) was selected from TCGA dataset. Promoter methylation of the gene panel was detected in 92.2% (83/90) of the training cohort with a specificity of 72.0% (18/25) and in 93.0% (40/43) of an independent cohort of stage IA primary NSCLC. In serum samples from the later 43 stage IA subjects and population-matched 42 control subjects, the gene panel yielded a sensitivity of 72.1% (31/41) and specificity of 71.4% (30/42). Similar diagnostic accuracy was observed in pleural effusion and ascites samples. A prognostic risk category based on the methylation status of CDO1, HOXA9, PTGDR, and AJAP1 refined the risk stratification for outcomes as an independent prognostic factor for an early-stage disease. Moreover, the paralog group for HOXA9, predominantly overexpressed in subjects with HOXA9 methylation, showed poor outcomes.Conclusions: Promoter methylation of a panel of 6 genes has potential for use as a biomarker for early cancer detection and to predict prognosis at the time of diagnosis. Clin Cancer Res; 23(22); 7141-52. ©2017 AACR.

Promoter methylation of MCAM, ERα and ERß in serum of early stage prostate cancer patients.

BACKGROUND: Prostate cancer (PC) is the second most common cancer among men worldwide. Currently, the most common non-invasive approach for screening and risk assessment of PC is measuring the level of serum prostate-specific antigen (PSA). However, the sensitivity of PSA is 42.8 % and specificity is 41.1%. As a result, the serum PSA test leads to numerous unneeded biopsies. Therefore, a rigorous search for biomarkers for early detection of PC is ongoing. In this study, we aim to assess a panel of epigenetic markers in an intend to develop an early detection test for PC. RESULTS: The sensitivity and specificity of hypermethylation of MCAM was 66% and 73% respectively which is an improvement from the sensitivity and specificity of PSA. Considering a combination marker panel of MCAM, ERα and ERß increased the sensitivity to 75% and the specificity became 70% for the minimally invasive early detection test of PC. MATERIALS AND METHODS: Sixteen primary matched tumor and serum were analyzed by quantitative methylation specific PCR (QMSP) to determine analytical and clinical sensitivity of the genes tested (SSBP2, MCAM, ERα, ERß, APC, CCND2, MGMT, GSTP1, p16 and RARß2). Additionally, serum samples from eighty four cases of PC, thirty controls and seven cases diagnosed as high grade Prostatic Intraepithelial Neoplasia (HGPIN) were analyzed. CONCLUSIONS: Promoter methylation of MCAM, ERα and ERß have a potential to be utilized as biomarker for the early detection of prostate PC as their sensitivity and specificity seem to be better than serum PSA in our cohort of samples. After robust validation in a larger prospective cohort, our findings may reduce the numbers of unwarranted prostate biopsies.

Identification and Validation of Protein Biomarkers of Response to Neoadjuvant Platinum Chemotherapy in Muscle Invasive Urothelial Carcinoma.

BACKGROUND: The 5-year cancer specific survival (CSS) for patients with muscle invasive urothelial carcinoma of the bladder (MIBC) treated with cystectomy alone is approximately 50%. Platinum based neoadjuvant chemotherapy (NAC) plus cystectomy results in a marginal 5-10% increase in 5-year CSS in MIBC. Interestingly, responders to NAC (

Gemcitabine and cisplatin neoadjuvant chemotherapy for muscle-invasive urothelial carcinoma: Predicting response and assessing outcomes.

PURPOSE: To evaluate gemcitabine-cisplatin (GC) neoadjuvant cisplatin-based chemotherapy (NAC) for pathologic response (pR) and cancer-specific outcomes following radical cystectomy (RC) for muscle-invasive bladder cancer and identify clinical parameters associated with pR. MATERIALS AND METHODS: We studied 150 consecutive cases of muscle-invasive bladder cancer that received GC NAC followed by open RC (2000-2013). A cohort of 121 patients treated by RC alone was used for comparison. Pathologic response and cancer-specific survival (CSS) were compared. We created the Johns Hopkins Hospital Dose Index to characterize chemotherapeutic dosing regimens and accurately assess sufficient neoadjuvant dosing regarding patient tolerance. RESULTS: No significant difference was noted in 5-year CSS between GC NAC (58%) and non-NAC cohorts (61%). The median follow-up was 19.6 months (GC NAC) and 106.5 months (non-NAC). Patients with residual non-muscle-invasive disease after GC NAC exhibit similar 5-year CSS relative to patients with no residual carcinoma (P = 0.99). NAC pR (≤ pT1) demonstrated improved 5-year CSS rates (90.6% vs. 27.1%, P < 0.01) and decreased nodal positivity rates (0% vs. 41.3%, P<0.01) when compared with nonresponders (≥ pT2). Clinicopathologic outcomes were inferior in NAC pathologic nonresponders when compared with the entire RC-only-treated cohort. A lower pathologic nonresponder rate was seen in patients tolerating sufficient dosing of NAC as stratified by the Johns Hopkins Hospital Dose Index (P = 0.049), congruent with the National Comprehensive Cancer Network guidelines. A multivariate classification tree model demonstrated 60 years of age or younger and clinical stage cT2 as significant of NAC response (P< 0.05). CONCLUSIONS: Pathologic nonresponders fare worse than patients proceeding directly to RC alone do. Multiple predictive models incorporating clinical, histopathologic, and molecular features are currently being developed to identify patients who are most likely to benefit from GC NAC.

Involvement of epigenetics and EMT-related miRNA in arsenic-induced neoplastic transformation and their potential clinical use.

Exposure to toxicants leads to cumulative molecular changes that overtime increase a subject's risk of developing urothelial carcinoma. To assess the impact of arsenic exposure at a time progressive manner, we developed and characterized a cell culture model and tested a panel of miRNAs in urine samples from arsenic-exposed subjects, urothelial carcinoma patients, and controls. To prepare an in vitro model, we chronically exposed an immortalized normal human bladder cell line (HUC1) to arsenic. Growth of the HUC1 cells was increased in a time-dependent manner after arsenic treatment and cellular morphology was changed. In a soft agar assay, colonies were observed only in arsenic-treated cells, and the number of colonies gradually increased with longer periods of treatment. Similarly, invaded cells in an invasion assay were observed only in arsenic-treated cells. Withdrawal of arsenic treatment for 2.5 months did not reverse the tumorigenic properties of arsenic-treated cells. Western blot analysis demonstrated decreased PTEN and increased AKT and mTOR in arsenic-treated HUC1 cells. Levels of miR-200a, miR-200b, and miR-200c were downregulated in arsenic-exposed HUC1 cells by quantitative RT-PCR. Furthermore, in human urine, miR-200c and miR-205 were inversely associated with arsenic exposure (P = 0.005 and 0.009, respectively). Expression of miR-205 discriminated cancer cases from controls with high sensitivity and specificity (AUC = 0.845). Our study suggests that exposure to arsenic rapidly induces a multifaceted dedifferentiation program and miR-205 has potential to be used as a marker of arsenic exposure as well as a maker of early urothelial carcinoma detection.

An epigenetic marker panel for recurrence risk prediction of low grade papillary urothelial cell carcinoma (LGPUCC) and its potential use for surveillance after transurethral resection using urine.

By a candidate gene approach, we analyzed the promoter methylation (PM) of 8 genes genes (ARF, TIMP3, RAR-ß2, NID2, CCNA1, AIM1, CALCA and CCND2) by quantitative methylation specific PCR (QMSP) in DNA of 17 non-recurrent and 19 recurrent noninvasive low grade papillary urothelial cell carcinoma (LGPUCC) archival tissues. Among the genes tested, by establishing an empiric cutoff value, CCND2, CCNA1, NID2, and CALCA showed higher frequency of methylation in recurrent than in non-recurrent LGPUCC: CCND2 10/19 (53%) vs. 2/17 (12%) (p=0.014); CCNA1 11/19 (58%) vs. 4/17 (23.5%) (p=0.048); NID2 13/19 (68%) vs. 3/17 (18%) (p=0.003) and CALCA 10/19 (53%) vs. 4/17 (23.5%) (p=0.097), respectively. We further analyzed PM of CCND2, CCNA1, and CALCA in urine DNA from UCC patients including LGPUCC and controls. The frequency of CCND2, CCNA1 and CALCA was significantly higher (p<0.0001) in urine of UCC cases [ 38/148 (26%), 50/73 (68%) and 94/148 (63.5%) respectively] than controls [0/56 (0%), 10/60 (17%) and 16/56 (28.5%), respectively)]. Most importantly we found any one of the 3 markers methylation positive in 25 out of 30 (83%) cytology negative LGPUCC cases. We also explored the biological function of CCNA1 in UCC. Prospective confirmatory studies are needed to develop a reliable tool for prediction of recurrence using primary LGPUCC tissues and/or urine.

SH3GL2 is frequently deleted in non-small cell lung cancer and downregulates tumor growth by modulating EGFR signaling.

The purpose of this study was to identify key genetic pathways involved in non-small cell lung cancer (NSCLC) and understand their role in tumor progression. We performed a genome wide scanning using paired tumors and corresponding 16 mucosal biopsies from four follow-up lung cancer patients on Affymetrix 250K-NSpI array platform. We found that a single gene SH3GL2 located on human chromosome 9p22 was most frequently deleted in all the tumors and corresponding mucosal biopsies. We further validated the alteration pattern of SH3GL2 in a substantial number of primary NSCLC tumors at DNA and protein level. We also overexpressed wild-type SH3GL2 in three NSCLC cell lines to understand its role in NSCLC progression. Validation in 116 primary NSCLC tumors confirmed frequent loss of heterozygosity of SH3GL2 in overall 51 % (49/97) of the informative cases. We found significantly low (p = 0.0015) SH3GL2 protein expression in 71 % (43/60) primary tumors. Forced overexpression of wild-type (wt) SH3GL2 in three NSCLC cell lines resulted in a marked reduction of active epidermal growth factor receptor (EGFR) expression and an increase in EGFR internalization and degradation. Significantly decreased in vitro (p = 0.0015-0.030) and in vivo (p = 0.016) cellular growth, invasion (p = 0.029-0.049), and colony formation (p = 0.023-0.039) were also evident in the wt-SH3GL2-transfected cells accompanied by markedly low expression of activated AKT(Ser(473)), STAT3 (Tyr(705)), and PI3K. Downregulation of SH3GL2 interactor USP9X and activated ß-catenin was also evident in the SH3GL2-transfected cells. Our results indicate that SH3GL2 is frequently deleted in NSCLC and regulates cellular growth and invasion by modulating EGFR function.

OGDHL is a modifier of AKT-dependent signaling and NF-κB function.

Oxoglutarate dehydrogenase (OGDH) is the first and rate-limiting component of the multi-enzyme OGDH complex (OGDHC) whose malfunction is associated with neuro-degeneration. The essential role of this complex is in the degradation of glucose and glutamate and the OGDHL gene (one component of OGDHC) is down-regulated by promoter hypermethylation in many different cancer types. These properties suggest a potential growth modulating role of OGDHL in cancer; however, the molecular mechanism through which OGDHL exerts its growth modulating function has not been elucidated.Here, we report that restoration of OGDHL expression in cervical cancer cells lacking endogenous OGDHL expression suppressed cell proliferation, invasion and soft agar colony formation in vitro. Knockdown of OGDHL expression in cervical cancer cells expressing endogenous OGDHL had the opposite effect. Forced expression of OGDHL increased the production of reactive oxygen species (ROS) leading to apoptosis through caspase 3 mediated down-regulation of the AKT signaling cascade and decreased NF-κB phosphorylation. Conversely, silencing OGDHL stimulated the signaling pathway via increased AKT phosphorylation. Moreover, the addition of caspase 3 or ROS inhibitors in the presence of OGDHL increased AKT signaling and cervical cancer cell proliferation.Taken together, these data suggest that inactivation of OGDHL can contribute to cervical tumorigenesis via activation of the AKT signaling pathway and thus support it as an important anti-proliferative gene in cervical cancer.

A single nucleotide polymorphism in the human PIGK gene associates with low PIGK expression in colorectal cancer patients.

Colorectal cancer (CRC) represents one of the highest incidences of cancers worldwide. Phosphatidylinositol glycan, class K (PIGK), is a crucial member of the glycosyl-phosphatidylinositol transamidase (GPIT) protein complex that attaches a diverse group of macromolecules to the plasma membrane of eukaryotes. However, the precise role of PIGK in tumorigenesis remains largely unknown. Recently, we reported low expression of PIGK protein in primary tumors compared to paired normal tissues of colorectal cancer (CRC) patients. To understand the mechanism underlying this phenomenon, we performed sequencing of all 10 exons of the PIGK gene in 45 CRC patients. Corresponding PIGK protein expression was also evaluated in these patients by immunohistochemistry. No mutation was detected in the coding regions, however, we found a single nucleotide polymorphism (C/C→C/G or G/G; rs1048575) in the 3'UTR of the PIGK gene in 67% (30/45) of the patients. Most of the patients (22/26, 85%) with the altered alleles were of Jewish origin. In comparison, 47% (8/17) of the Arabian patients exhibited the altered C/G alleles. We observed a significantly low (p<0.002) expression of PIGK protein in the patients with the altered alleles (C/G or G/G) compared to the ancestral alleles (C/C). Similarly to the CRC patients, we also examined 5 HCC patients and two HCC cell lines (Hep3B and HepG2) for PIGK genotype (SNP-1048575) and corresponding protein expression. We observed altered alleles (C/G or G/G) and corresponding low PIGK protein expression in 4 out of 5 (80%) primary HCC tumors. Among the HCC cell lines, HepG2 line exhibited ancestral C/C alleles, whereas Hep3B showed altered C/G alleles. Similar to the HCC patients, Hep3B line with the altered alleles (C/G) exhibited significantly low (Student's t-test, p<0.002) PIGK protein expression compared to the Hep3B line carrying the ancestral (C/C) alleles. To examine the exogenous PIGK protein expression status, we transiently transfected both HepG2 (C/C alleles) and Hep3B (C/G alleles) cell lines with wt-PIGK constructs. We detected exogenously expressed PIGK protein in HepG2 (C/C) cells, but no PIGK expression was detectable in Hep3B (C/G) cells at either mRNA or protein level. Our results demonstrate, for the first time, a link between the SNP 1048575 and low PIGK expression in CRC/HCC patients and also suggest a possible association between altered PIGK expression and disease susceptibility.

An epigenetic marker panel for detection of lung cancer using cell-free serum DNA.

PURPOSE: We investigated the feasibility of detecting aberrant DNA methylation of some novel and known genes in the serum of lung cancer patients. EXPERIMENTAL DESIGN: To determine the analytic sensitivity, we examined the tumor and the matched serum DNA for aberrant methylation of 15 gene promoters from 10 patients with primary lung tumors by using quantitative methylation-specific PCR. We then tested this 15-gene set to identify the more useful DNA methylation changes in the serum of a limited number of lung cancer patients and controls. In an independent set, we tested the six most promising genes (APC, CDH1, MGMT, DCC, RASSF1A, and AIM1) for further elucidation of the diagnostic application of this panel of markers. RESULTS: Promoter hypermethylation of at least one of the genes studied was detected in all 10 lung primary tumors. In majority of cases, aberrant methylation in serum DNA was accompanied by methylation in the matched tumor samples. In the independent set, using a single gene that had 100% specificity (DCC), 35.5% (95% CI: 25-47) of the 76 lung cancer patients were correctly identified. For patients without methylated DCC, addition of a logistic regression score that was based on the five remaining genes improved sensitivity from 35.5% to 75% (95% CI: 64-84) but decreased the specificity from 100% to 73% (95% CI: 54-88). CONCLUSION: This approach needs to be evaluated in a larger test set to determine the role of this gene set in early detection and surveillance of lung cancer.

DeltaNp63alpha confers tumor cell resistance to cisplatin through the AKT1 transcriptional regulation.

Strategies to address resistance to platin drugs are greatly needed in human epithelial cancers (e.g., ovarian, head/neck, and lung) where platins are used widely and resistance occurs commonly. We found that upon ΔNp63α overexpression, AKT1 and phospho-AKT1 levels are upregulated in cancer cells. Investigations using gel-shift, chromatin immunoprecipitation and functional reporter assays implicated ΔNp63α in positive regulation of AKT1 transcription. Importantly, we found that ΔNp63α, AKT1, and phospho-AKT levels are greater in 2008CI3 CDDP-resistant ovarian cancer cells than in 2008 CDDP-sensitive cells. siRNA-mediated knockdown of ΔNp63α expression dramatically decreased AKT1 expression, whereas knockdown of either ΔNp63α or AKT1 decreased cell proliferation and increased death of ovarian and head/neck cancer cells. Conversely, enforced expression of ΔNp63α increased cancer cell proliferation and reduced apoptosis. Together, our findings define a novel ΔNp63α-dependent regulatory mechanism for AKT1 expression and its role in chemotherapeutic resistance of ovarian and head/neck cancer cells.

Genetic and epigenetic analysis of erbB signaling pathway genes in lung cancer.

BACKGROUND: Prognosis for patients with non-small cell lung cancer (NSCLC) is poor. The potential value of modulating epidermal growth factor receptor (EGFR) for treatment is reflected by the recent approval of specific drugs that inhibit its activity. Mutations in EGFR were reported in lung cancer and generated interest, once they enable the identification of lung cancers likely to respond to various targeted small molecules. METHODS: We tested three key genetic and epigenetic alterations (EGFR, RASSF1A, and BRAF) of this pathway on a series of primary NSCLC (total 111; adenocarcinoma 49, squamous cell carcinoma [SCC] 48, and others 14). The mutational status of KRAS (and p53) was known for these samples. The purpose of this study was to define the pattern of erbB pathway alterations in NSCLC and to test for associations with clinical parameters. RESULTS: Five EGFR mutations were identified: three in adenocarcinoma (6%), one in SCC (2%), and one in adenocarcinoma with bronchoalveolar component tumor (7%). EGFR mutations included three in-frame deletions in exon 19 and two point mutations in exon 21. Promoter methylation of RASSF1A was detected in 25 of 45 adenocarcinomas and 18 of 46 SCC. Mutations of EGFR, BRAF, and KRAS in adenocarcinoma were mutually exclusive and inversely correlated with RASSF1A methylation (p = -0.394; p = 0.007). DISCUSSION: Overall, genetic and/or epigenetic alterations of erbB pathway genes were detected in 80% (39/49) of adenocarcinomas.Approximately half of primary adenocarcinoma harbor molecular alterations of the erbB pathway. Careful characterization of these alterations and response to anti-EGFR therapies is warranted to determine better and accurate determinants of clinical response.