Stem Cell Cancer Research Articles

Role of miRNA-145, 148, and 185 and Stem Cells in Prostate Cancer.

MicroRNAs (miRNAs) are small non-coding RNA molecules that play a role in cancer linked to the regulation of important cellular processes and pathways involving tumorigenesis, cell proliferation, differentiation, and apoptosis. A lot of human miRNA sequences have been identified which are linked to cancer pathogenesis. MicroRNAs, in prostate cancer (PC), play a relevant role as biomarkers, show a specific profile, and have been used as therapeutic targets. Prostate cancer (PC) is the most frequently diagnosed cancer in men. Clinical diagnoses among the gold standards for PC diagnosis and monitoring are prostate-specific antigen (PSA) testing, digital rectal examination, and prostate needle biopsies. PSA screening still has a large grey area of patients, which leads to overdiagnosis. Therefore, new biomarkers are needed to improve existing diagnostic tools. The miRNA expression profiles from tumour versus normal tissues are helpful and exhibit significant differences not only between cancerous and non-cancerous tissues, but also between different cancer types and subtypes. In this review, we focus on the role of miRNAs-145, 148, and 185 and their correlation with stem cells in prostate cancer pathogenesis. MiR-145, by modulating multiple oncogenes, regulates different cellular processes in PC, which are involved in the transition from localised to metastatic disease. MiR-148 is downregulated in high-grade tumours, suggesting that the miR-148-3 family might act as tumour suppressors in PC as a potential biomarker for detecting this disease. MiR-185 regulation is still unclear in being able to regulate tumour processes in PC. Nevertheless, other authors confirm the role of this miRNA as a tumour suppressor, suggesting its potential use as a suitable biomarker in disease prognosis. These three miRNAs are all involved in the regulation of prostate cancer stem cell behaviour (PCSCs). Within this contest, PCSCs are often involved in the onset of chemo-resistance in PC, therefore strategies for targeting this subset of cells are strongly required to control the disease. Hence, the relationship between these two players is interesting and important in prostate cancer pathogenesis and in PCSC stemness regulation, in the attempt to pave the way for novel therapeutic targets in prostate cancer.

Rivaroxaban targets procoagulant fibroblasts in the tumour microenvironment to reduce breast cancer cell migration and stem cell activity

Introduction: Breast cancer-associated fibroblasts express tissue factor (TF), creating a procoagulant tumour microenvironment. TF activates PAR2 to promote cancer cell proliferation, metastasis and stem cell activity. Rivaroxaban, a licensed oral anticoagulant which inhibits TF-FVIIa-FXa, could be repurposed as an anticancer therapy. We hypothesise that a procoagulant microenvironment will induce breast cancer progression and that this will be inhibited by Rivaroxaban.

Abstract PO-157: Calcium/calmodulin-dependent protein kinase-related peptide (CARP) increases stemness of colorectal cancer cells

Abstract Calcium/calmodulin-dependent protein kinase-related peptide (CARP) is one of the five alternative splicing products of the doublecortin-like kinase 1 (DCLK1) gene, which is a specific marker for cancer stem cells in multiple cancers. Up-regulation of DCLK1 is correlated with progression and poor prognosis of malignant cancers, but the role of individual DCLK1 isoforms during tumorigenesis is unclear. CARP was reported to play an important role in the hippocampus and in the facilitation of apoptosis in granule cells of the rat dentate gyrus. Here we aimed to reveal the effects of CARP on the stemness of cancer cells. In order to achieve our goal, isogenic CARP over-expressing cells were established using HCT116 cells, a colorectal cancer cell line. Spheroid formation assay, proliferation assay, and clonogenic capacity assay were applied to assess the effects of CARP on cancer biology. Our results demonstrated that over-expression of CARP increased the number of spheroids, but decreased the proliferation rate in comparison to parental control HCT116 cells. In conclusion, CARP can increase the self-renewal capability of cancer cells under spheroid formation conditions, but can also inhibit cell proliferation under normal cell culture conditions. CARP may be used to develop a therapeutic target for cancer treatment. Citation Format: Leo Mei, Jinghe Mao. Calcium/calmodulin-dependent protein kinase-related peptide (CARP) increases stemness of colorectal cancer cells [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-157.

GD2+ cancer stem cells in triple-negative breast cancer: mechanisms of resistance to breast cancer therapies.

Research has led to the development of tailored treatment options for different cancers in different patients. Despite some treatments being able to provide remarkable responses, nearly all current treatments encounter the same issue: resistance. Here, we discuss our experiences with how breast cancers resist therapies. The focus of our discussion revolves around the cancer stem cell subpopulation and their mechanisms for resistance.

New stem cell autophagy surrogate diagnostic biomarkers in early-stage hepatocellular carcinoma in Egypt: A pilot study.

BACKGROUNDStem cell autophagy disruption is responsible for the development of hepatocellular carcinoma (HCC). Many non-coding RNAs are linked to the activation and inhibition of certain genes. The SQSTM1 gene controls stem cell autophagy as shown in previous studies. The upregulation of SQSTM1 is associated with the inhibition of autophagy in cancerous stem cells in patients with HCC. AIMTo determine whether serum microRNA, hsa-miR-519d, is linked to SQSTM1 gene and whether they could be used as diagnostic biomarkers for early-stage HCC.METHODS In silico analysis was performed to determine the most correlated genes of autophagy with microRNAs. SQSTM1 and hsa-miR-519d were validated through this pilot clinical study. This study included 50 Egyptian participants, who were classified into three subgroups: Group 1 included 34 patients with early-stage HCC, Group 2 included 11 patients with chronic liver disease, and Group 3 (control) included 5 healthy subjects. All patients were subjected to full laboratory investigations, including viral markers and alpha-fetoprotein (AFP), abdominal ultrasound, and clinical assessment with the Child–Pugh score calculation. Besides, the patients with HCC underwent triphasic computed tomography with contrast to diagnose and determine the tumor site, size, and number. Quantitative real-time polymerase chain reaction was used to assess hsa-miR-519d-3p and SQSTM1 in the serum of all the study participants.RESULTSHsa-miR-519d-3p was significantly upregulated in patients with HCC compared with those with chronic liver disease and healthy subjects with an area under the curve (AUC) of 0.939, with cutoff value 8.34, sensitivity of 91.2%, and specificity of 81.8%. SQSTM1 was upregulated with an AUC of 0.995, with cutoff value 7.89, sensitivity of 97.1%, and specificity of 100%. AFP significantly increased in patients with HCC with an AUC of 0.794, with cutoff value 7.30 ng/mL, sensitivity of 76.5%, and specificity of 72.7%.CONCLUSIONThis study is the first to show a direct relation between SQSTM1 and hsa-miR-519d-3p; they are both upregulated in HCC. Thus, they could be used as surrogate diagnostic markers for stem cell autophagy disturbance in early-stage HCC.

BIX-01294 enhances the effect of chemotherapy on colorectal cancer by inhibiting the expression of stemness genes

During the development of colorectal cancer, tumor cells will generate some cancer stem cells with self-renewal ability because they adapt to the environment. Therefore, in the treatment of colorectal cancer, it has certain potential clinical application value to effectively inhibit cancer stem cells. A small molecule EHMT-2 inhibitor, BIX-01294, was evaluated for its activity in inhibiting cancer stem cells in human colorectal cancer by in vitro and in vivo experiments. Transcriptome analysis was performed on BIX-01294 treated cells for holistic analysis to elucidate how BIX-01294 inhibits the expression of genes related to cancer stem cells. The results show that BIX-01294 significantly inhibited the proliferative phenotype of human colorectal cancer in vivo and in vitro, reduced the proportion of cancer stem cells, and inhibited some stemness-related gene. Morever, it is synergistic with 5-fluorouracil in inhibiting the proliferation of colorectal cancer. In summary, EHMT-2 is a novel target of anti-tumor drugs. The combination of BIX-01294 and 5-fluorouracil has a synergistic therapeutic effect on human colorectal cancer.

The Roles of RNA N6-Methyladenosine in Regulating Stem Cell Fate.

RNA N6-methyladenosine (m6A) modification has important regulatory roles in determining cell fate. The reversible methylation process of adding and removing m6A marks is dynamically regulated by a fine-tuned coordination of many enzymes and binding proteins. Stem cells have self-renewal and pluripotent potential and show broad prospects in regenerative medicine and other fields. Stem cells have also been identified in cancer, which is linked to cancer metastasis, therapy resistance, and recurrence. Herein, we aimed to review the molecular mechanism that controls the reversible balance of m6A level in stem cells and the effect of m6A modification on the balance between pluripotency and differentiation. Additionally, we also elaborated the association between aberrant m6A modification and the maintenance of cancer stem cells in many cancers. Moreover, we discussed about the clinical implications of m6A modification in cancer stem cells for cancer diagnosis and therapy.

Arl4c promotes the growth and drug resistance of pancreatic cancer by regulating tumor-stromal interactions

SummaryEmerging evidence suggests that ADP-ribosylation factor like-4c (Arl4c) may be a potential choice for cancer treatment. However, its role in pancreatic cancer, especially in tumor-stroma interactions and drug resistance, is still unknown. In the current study, we examined the proliferation and drug resistance effect of Arl4c on pancreatic cancer cells. Furthermore, we explored the contribution of Arl4c high expression in pancreatic stellate cell (PSC) activation. We found that high Arl4c expression is associated with cell proliferation, drug resistance, and PSC activation. In detail, Arl4c regulates connective tissue growth factor (CTGF) paracrine, further induces autophagic flux in PSCs, resulting in PSC activation. TGFβ1 secreted by activated PSCs enhances cancer cell stem cell properties via smad2 signaling, further increasing cell drug resistance. YAP is an important mediator of the Arl4c-CTGF loop. Taken together, these results suggest that Arl4c is essential for pancreatic cancer progression and may be an effective therapeutic choice.

HES1 protein oscillations are necessary for neural stem cells to exit from quiescence

SummaryQuiescence is a dynamic process of reversible cell cycle arrest. High-level persistent expression of the HES1 transcriptional repressor, which oscillates with an ultradian periodicity in proliferative neural stem cells (NSCs), is thought to mediate quiescence. However, it is not known whether this is due to a change in levels or dynamics. Here, we induce quiescence in embryonic NSCs with BMP4, which does not increase HES1 level, and we find that HES1 continues to oscillate. To assess the role of HES1 dynamics, we express persistent HES1 under a moderate strength promoter, which overrides the endogenous oscillations while maintaining the total HES1 level within physiological range. We find that persistent HES1 does not affect proliferation or entry into quiescence; however, exit from quiescence is impeded. Thus, oscillatory expression of HES1 is specifically required for NSCs to exit quiescence, a finding of potential importance for controlling reactivation of stem cells in tissue regeneration and cancer.

Ethanolic extract of sappan wood (Caesalpinia sappan L.) inhibits MCF-7 and MCF-7/HER2 mammospheres' formation: an in vitro and bioinformatic study

One of the mechanisms of cancer cell resistance toward chemotherapy is through cancer stem cells (CSCs), which are characterized by excessive activation of regulator proteins such as human epidermal receptor 2 (HER2). Sappan wood (Caesalpinia sappan L.) contains brazilin and brazilein that exhibit cytotoxic effects on several cancer cell lines. We aimed to explore the potency of the ethanolic extract of sappan (EES) in CSCs through bioinformatic analyses and by using a three-dimensional (3D) breast cancer stem cells (BCSCs) for in vitro assay with two different models (i.e., BCSCs and HER2-BCSCs) in order to identify the potential therapeutic targets of genes (PTTGs). Bioinformatic analyses identified PTTGs, which were further analyzed by gene ontology, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, protein-protein interaction (PPI) networks, and hub protein selection. Mammospheres were cultured under conditioned media. The cytotoxic effects of EES were then measured by direct counting and based on the mammosphere-forming potential (MFP). Bioinformatic analysis disclosed PIK3CA and TP53 as PTTGs in BCSCs and HER2-BCSCs, respectively. In addition, the KEGG pathway analyses also demonstrated that PTTGs could regulate the ERBB pathway. EES thus demonstrated cytotoxicity and inhibited the formation of mammospheres. Collectively, EES exhibited excellent potential for further development as an inhibitor of cancer stem cells in breast cancer.

Molecular modeling studies of the effects of withaferin A and its derivatives against oncoproteins associated with breast cancer stem cell activity

Cancer stem cells (CSCs) in breast cancers are considered to be a major cause of tumor recurrence and metastasis, which lead to chemotherapeutic failures and poor survival rates among breast cancer patients. Hence, this study attempted to evaluate the anti-tumor potential of a bioactive withanolide compound, withaferin A (WFA), against the molecular targets that maintain the stemness of breast cancer stem cells, using in silico molecular modeling approach. The crystal structures of potential breast cancer stem cell targets—HSP70, HSP90, NFκB, and BRCA1 were retrieved from PDB. The 2D structures of WFA, its analogs, along with doxorubicin and vinblastine were retrieved from the PubChem database. WFA and withaferin A diacetate exhibited strong receptor-ligand interactions for the target macromolecules. Their binding energy values ranged between –55.241 and –40.250 kcal/mol. Compared to doxorubicin, WFA markedly inhibited the growth and decreased the viability of MCF-7-derived breast cancer stem cells, with an IC50 value of 1.476 μM for 48 h. Therefore, our results indicate that WFA and its derivatives could be promising anti-tumor agents against breast cancer stem cells. Further in vitro studies are warranted in order to gain a greater understanding of the action of this compound in a physiological setting.

Cancerous and non-neoplastic stem cells in the stomach similarly express CD44 and CD133

CD44 and CD133 have been considered as cancer stem cell (CSC) markers. Stem cell markers are rarely described in healthy stomach tissues. However, the clinicopathological and prognostic value of CD44 and CD133 in gastric cancer remains controversial. This study investigated the expression of CD44 and CD133 in gastric cancer and non-neoplastic gastric mucosa. We used samples of primary gastric adenocarcinomas (n = 69), metastatic lymph nodes (n = 30), intestinal metaplasia (n = 17), and histologically normal gastric tissues of surgical margins (n = 54). The expression of CD44 and CD133 were studied in samples by immunohistochemistry. Fisher’s exact test and a logistic regression model were used in this study. CD44 expression was observed in 12% of samples with intestinal metaplasia, 20% with lymph node metastases, 22% with normal mucosa, to 30% of samples with primary tumors. Most of these positive tumors showed immunostaining in less than 4% of cancerous cells, mainly in the diffuse type. CD133 expression was observed in 7% (intestinal metaplasia) to 46% (normal mucosa). In the positive cases of cancer (24%), in most of them, less than 3% of cells were marked. CD44 and CD133 expression in the histologically normal gastric mucosa was restricted to the deeper regions of the gastric crypts at the level where stem cells and progenitor cells are usually found. CD44 and CD133 expression occurs in few gastric cancer cells, mainly in diffuse carcinomas, and are expressed in histologically normal gastric mucosae. None of the markers are specific for cancer and are also present in intestinal metaplasia and the normal mucosa.

A Pilot Study Investigating the Expression Levels of Pluripotency-Associated Genes in Rectal Swab Samples for Colorectal Polyp and Cancer Diagnosis and Prognosis

Change in gene expression is inevitable in cancer development. With more studies demonstrating the contributions of cancer stem cells (CSCs) in colorectal cancer (CRC) development, this study is aimed at investigating whether rectal swab specimen serves as a tool for detection of dysregulation of CSC or stem cell (SC) markers and at evaluating its potential as a new promising screening method for high-risk patients. Expression levels of 15 pluripotency-associated genes were assessed by quantitative PCR in 53 rectal swab specimens referred for endoscopic screening. Dysregulated genes and joint panels based on such genes were examined for their diagnostic potentials for both polyp and CRC. Out of 15 genes, Oct4, CD26, c-MYC, and CXCR4 showed significantly differential expression among normal, polyp, and CRC patients. A panel of Oct4 and CD26 showed an AUC value of 0.80 (p = 0.003) in identifying CRC patients from polyp/normal subjects, with sensitivity and specificity of 84.6% and 69.2%. A panel of c-MYC and CXCR4 achieved CRC/polyp identification with an AUC value of 0.79 (p = 0.002), with a sensitivity of 82.8% and specificity of 80.0%. The sensitivity for polyp and CRC was 80.0% and 85.7%, respectively. Further analysis showed that higher c-MYC and CXCR4 level was detected in normal subjects who developed polyps after 5-6 years, in comparison with subjects with no lesion developed, and the AUC of the c-MYC and CXCR4 panel increased to 0.88 (p < 0.001), with sensitivity and specificity of 84.4% and 92.3%, respectively, when these patients were included in the polyp group. This study suggests that the Oct4 and CD26 panel is a promising biomarker for distinguishing CRC from normal and polyp patients, whereas the c-MYC and CXCR4 panel may identify polyp and CRC from normal individuals.

Abstract 3090: Targeting WNT and retinoid signaling pathways to promote differentiation of cancer stem cells along the neuroendocrine lineage in CRC

Abstract Since APC mutations lead to overpopulation of ALDH+ stem cells (SCs) in colorectal cancers (CRCs) and that ALDH is a key component of the retinoic acid (RA) signaling pathway, the hypothesis was developed that human CRC evolves due to an imbalance between WNT and RA signaling. Indeed, we previously discovered that progressive overpopulation of ALDH+ SCs occurs in normal, mutant, adenomatous, and malignant colon crypt tissues, which coincided with the change in the APC mutation zygosity state in familial adenomatous polyposis (FAP) patients. Therefore, the SC overpopulation that drives development of CRC appears to result from dysregulated WNT signaling, of which APC is a negative regulator. Normal colonic SC differentiation is feedback regulated by neuroendocrine cells (NECs) that reside adjacent to SCs in the bottom of the colon crypt. Our goal was to determine if APC mutation and subsequent dysregulated WNT signaling contributes to the inability of SCs to differentiate into NECs, leading to overpopulation of cancer SCs (CSCs) during tumor development. Although RA signaling is altered in CRC, we still found that all- trans-retinoic acid (ATRA) could reduce the number of ALDH+ CSCs in several CRC cell lines. We also found that administering ATRA promotes differentiation of CSCs along the neuroendocrine lineage. Moreover, induction of wild-type (wt)-APC expression in HT29 CRC cells led to increased expression of several NEC markers including CGA, GLP2R, NSE, SSTR1; and decreased WNT/β-catenin signaling when tested via TCF reporter assay. Inducing wt-APC also led to reduced β-catenin and change in protein expression of several proteins known to be targeted by WNT signaling including c-MYC, c-JUN, MET, and CD44. Our preliminary results also show that inducing wt-APC expression increases the number of GLPR2+ NECs. Thus, a link between WNT and RA signaling provides a possible mechanism that might explain how mutant APC leads to decreased maturation of ALDH+ SCs along the NEC lineage and an increased the number of ALDH+ SCs. Therefore, discovering ways to increase differentiation of SCs along the NEC lineage in vivo might lead to new more effective treatment strategies for CRC patients. Citation Format: Caroline O. Facey, Victoria O. Hunsu, Brian T. Osmond, Lynn M. Opdenaker, Bruce M. Boman. Targeting WNT and retinoid signaling pathways to promote differentiation of cancer stem cells along the neuroendocrine lineage in CRC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3090.

Carcinoma associated fibroblasts small extracellular vesicles with low miR-7641 promotes breast cancer stemness and glycolysis by HIF-1\u03b1

Fibroblasts play an important role in cancer development and progression. Small extracellular vesicles (sEVs) are one type of extracellular vesicles, which mediate the interaction between cancer-associated fibroblasts and cancer cells by transferring their contents. However, the roles of sEVs from cancer-associated fibroblasts on breast cancer stem cell properties are largely unraveled. The purpose of this study was to explore the roles of sEVs from cancer-associated fibroblasts on breast cancer progression. The miRNA array data showed a different miRNA profile between CAFs sEVs and normal fibroblasts sEVs. By verification using real-time RT-PCR, the data analysis indicated that miR-7641 levels were lower in sEVs from CAFs compared with NFs. The cellular functions were assayed and the results indicated that CAFs derived sEVs with low miR-7641 levels suppressed breast cancer cell survival, glycolysis, and stem cell properties via the HIF-1α pathway. Collectively, these findings indicated that sEVs from CAFs promoted breast cancer stem cell properties and glycolysis via miR-7641/HIF-1α, which was a possible new way for targeting breast cancer.

TrkA Interacts with and Phosphorylates STAT3 to Enhance Gene Transcription and Promote Breast Cancer Stem Cells in Triple-Negative and HER2-Enriched Breast Cancers.

Simple SummaryBreast cancer is the leading cancer in American women. Due to the inherent aggressiveness of triple-negative and HER2-enriched breast cancers, it is imperative to identify novel molecular targets for therapeutic intervention. Due to their abnormal activities in metastatic breast cancers, JAK2–STAT3 and TrkA pathways have been individually implicated in aggressive breast tumors. However, their co-activation and signaling interactions have not been thoroughly investigated. Therefore, our study aimed to elucidate the extent of crosstalk between JAK2–STAT3 and TrkA signaling pathways and its impact on breast cancer. Our data revealed a novel interaction between TrkA and STAT3, and that this interaction results in STAT3 phosphorylation and activation by TrkA, leading to enhanced stemness gene expression and stem cell renewal. We further found that the co-activation of JAK2–STAT3 and TrkA pathways is correlated with shorter time to develop overall and organ-specific metastasis, suggesting that this signaling crosstalk underlies the aggressiveness of triple-negative and HER2-enriched breast cancers.JAK2–STAT3 and TrkA signaling pathways have been separately implicated in aggressive breast cancers; however, whether they are co-activated or undergo functional interaction has not been thoroughly investigated. Herein we report, for the first time that STAT3 and TrkA are significantly co-overexpressed and co-activated in triple-negative breast cancer (TNBC) and HER2-enriched breast cancer, as shown by immunohistochemical staining and data mining. Through immunofluorescence staining–confocal microscopy and immunoprecipitation–Western blotting, we found that TrkA and STAT3 co-localize and physically interact in the cytoplasm, and the interaction is dependent on STAT3-Y705 phosphorylation. TrkA–STAT3 interaction leads to STAT3 phosphorylation at Y705 by TrkA in breast cancer cells and cell-free kinase assays, indicating that STAT3 is a novel substrate of TrkA. β-NGF-mediated TrkA activation induces TrkA–STAT3 interaction, STAT3 nuclear transport and transcriptional activity, and the expression of STAT3 target genes, SOX2 and MYC. The co-activation of both pathways promotes breast cancer stem cells. Finally, we found that TNBC and HER2-enriched breast cancer with JAK2–STAT3 and TrkA co-activation are positively associated with poor overall metastasis-free and organ-specific metastasis-free survival. Collectively, our study uncovered that TrkA is a novel activating kinase of STAT3, and their co-activation enhances gene transcription and promotes breast cancer stem cells in TNBC and HER2-enriched breast cancer.

Mesenchymal Stem Cells in Gastric Cancer: Vicious but Hopeful.

Tumor progression depends on the collaborative interactions between tumor cells and the surrounding stroma. First-line therapies direct against cancer cells may not reach a satisfactory outcome, such as gastric cancer (GC), with high risk of recurrence and metastasis. Therefore, novel treatments and drugs target the effects of stroma components are to be promising alternatives. Mesenchymal stem cells (MSC) represent the decisive components of tumor stroma that are found to strongly affect GC development and progression. MSC from bone marrow or adjacent normal tissues express homing profiles in timely response to GC-related inflammation signals and anchor into tumor bulks. Then the newly recruited “naïve” MSC would achieve phenotype and functional alternations and adopt the greater tumor-supporting potential under the reprogramming of GC cells. Conversely, both new-comers and tumor-resident MSC are able to modulate the tumor biology via aberrant activation of oncogenic signals, metabolic reprogramming and epithelial-to-mesenchymal transition. And they also engage in remodeling the stroma better suited for tumor progression through immunosuppression, pro-angiogenesis, as well as extracellular matrix reshaping. On the account of tumor tropism, MSC could be engineered to assist earlier diagnosis of GC and deliver tumor-killing agents precisely to the tumor microenvironment. Meanwhile, intercepting and abrogating vicious signals derived from MSC are of certain significance for the combat of GC. In this review, we mainly summarize current advances concerning the reciprocal metabolic interactions between MSC and GC and their underlying therapeutic implications in the future.

Thyroid Hormone and Estrogen Promote Endocrine Resistance, Proliferation, Dedifferentiation, and Cancer Stem Cells in Steroid Receptor-Positive Breast Cancers

Background: Breast cancer (BC) and thyroid disease are well-recognized comorbidities. Hyperthyroidism and supraphysiologic thyroid hormone (TH) have been shown to promote BC incidence. We recently reported that thyroid hormone replacement therapy (THRT) was significantly and independently associated with shortened disease-free and overall survival, as well as endocrine resistance only in patients with steroid receptor-positive (SR+) BC (1). TH markedly upregulated estrogen and cell cycle signaling in vivo and in vitro and promoted dedifferentiation to basaloid and pre-stem phenotypes. Metformin (Met) attenuated this shift. Mechanisms of TH-mediated endocrine therapy resistance in ER+ BC are the focus of this report. Design: Two clinical cohorts of early-stage lymph node-negative (LN-) SR+ BC patients (n=820 and n=160) were used to determine the effect of THRT on overall survival using Kaplan-Meier methods. Bi-directional cross-talk between TH and E2 was tested using different BC cell lines, ER+ PDX in vivo models, in vitro methods, and publically available in silico data for modeling. Results: Our results show that E2+TH increases cell proliferation, enhances cell cycle, and hormone-associated oncogenic signaling in SR+/ER+ BC. Given that high expression of THRA is associated with poor prognosis in SR+ BC, knockdown of THRA and ESR1 reduced cell proliferation in ER+ BC cells. ER+ PDX tumors were implanted into NSG mice containing E2 pellet and subsequently treated with TH, Tamoxifen (Tam), Fulvestrant (ICI) or Met. Our data show that TH-mediated endocrine resistance only in the E2+TH+Tam treated tumors (P<0.0001 vs E2+Tam alone). Both ICI and Met provided significant attenuation of tumor growth in vivo. RNAseq analysis of E2+TH+Tam tumors show an increase in pro-oncogenic signaling (Wnt/Fizzled, MMPs, and TCL/LEFT). Our data suggest that the use of Tam did not dampen tumor growth whereas a full ER-antagonist (ICI) or Met attenuated E2-TH mediated cross-talk and tumor growth. Conclusions: These findings suggest that TH+Tam may enhance oncogenic signaling and is associated with a significantly increase in mortality risk in ER+/SR+ BC tumors. Exogenous TH adversely affects SR+ BC and not SR- BC. Understanding the mechanism of cross-talk between TH and E2 allows us to define novel therapeutic strategies that will facilitate rapid clinical application for ER+ BC patients currently taking THRT and anti-estrogen treatments. Reference: (1) Wahdan-Alaswad et. al. Clin Cancer Res October 23 2020 DOI: 10.1158/1078-0432.CCR-20-264.

Non-Genomic Control of Dynamic MYCN Gene Expression in Liver Cancer.

Upregulated MYCN gene expression is restricted to specialized cell populations such as EpCAM+ cancer stem cells in liver cancer, regardless of DNA amplification and mutation. Here, we reviewed the role of MYCN gene expression in liver homeostasis, regeneration, and tumorigenesis, and discussed the potential non-genomic mechanisms involved in controlling MYCN gene expression in liver cancer, with a focus on inflammation-mediated signal transduction and microRNA-associated post-transcriptional regulation. We concluded that dynamic MYCN gene expression is an integrated consequence of multiple signals in the tumor microenvironment, including tumor growth-promoting signals, lipid desaturation-mediated endoplasmic reticulum stress adaptation signals, and tumor suppressive miRNAs, making it a potential predictive biomarker of tumor stemness and plasticity. Therefore, understanding and tracing the dynamic changes and functions of MYCN gene expression will shed light on the origin of liver tumorigenesis at the cellular level and the development of novel therapeutic and diagnostic strategies for liver cancer treatment.

Cancer stem cells in colorectal cancer and the association with chemotherapy resistance.

The incidence and mortality of colorectal cancer (CRC) have always been among the highest in the world, although the diagnosis and treatment are becoming more and more advanced. At present, the main reason is that patients have acquired drug resistance after long-term conventional drug treatment. An increasing number of evidences confirm the existence of cancer stem cells (CSCs), which are a group of special cells in cancer, only a small part of cancer cells. These special cell populations are not eliminated by chemotherapeutic drugs and result in tumor recurrence and metastasis after drug treatment. CSCs have the ability of self-renewal and multidirectional differentiation, which is associated with the occurrence and development of cancer. CSCs can be screened and identified by related surface markers. In this paper, the characteristic surface markers of CSCs in CRC and the related mechanism of drug resistance will be discussed in detail. A better understanding of the mechanism of CSCs resistance to chemotherapy may lead to better targeted therapy.