Characteristics of CD44 alternative splice pattern in the course of human colorectal adenocarcinoma progression

CD44: A New Prognostic Marker in Colorectal Cancer?

Cluster of differentiation 44 (CD44) is a non-kinase cell surface glycoprotein. It is overexpressed in several cell types, including cancer stem cells (CSCs). Cells overexpressing CD44 exhibit several CSC traits, such as self-renewal, epithelial-mesenchymal transition (EMT) capability, and resistance to chemo- and radiotherapy. The role of CD44 in maintaining stemness and the CSC function in tumor progression is accomplished by binding to its main ligand, hyaluronan (HA). The HA-CD44 complex activates several signaling pathways that lead to cell proliferation, adhesion, migration, and invasion. The CD44 gene regularly undergoes alternative splicing, resulting in the standard (CD44s) and variant (CD44v) isoforms. The different functional roles of CD44s and specific CD44v isoforms still need to be fully understood. The clinicopathological impact of CD44 and its isoforms in promoting tumorigenesis suggests that CD44 could be a molecular target for cancer therapy. Furthermore, the recent association observed between CD44 and KRAS-dependent carcinomas and the potential correlations between CD44 and tumor mutational burden (TMB) and microsatellite instability (MSI) open new research scenarios for developing new strategies in cancer treatment. This review summarises current research regarding the different CD44 isoform structures, their roles, and functions in supporting tumorigenesis and discusses its therapeutic implications.

RNA-binding proteins regulating the CD44 alternative splicing

Alternative splicing is often deregulated in cancer, and cancer-specific isoform switches are part of the oncogenic transformation of cells. Accumulating evidence indicates that isoforms of the multifunctional cell-surface glycoprotein CD44 play different roles in cancer cells as compared to normal cells. In particular, the shift of CD44 isoforms is required for epithelial to mesenchymal transition (EMT) and is crucial for the maintenance of pluripotency in normal human cells and the acquisition of cancer stem cells phenotype for malignant cells. The growing and seemingly promising use of splicing inhibitors for treating cancer and other pathologies gives hope for the prospect of using such an approach to regulate CD44 alternative splicing. This review integrates current knowledge about regulating CD44 alternative splicing by RNA-binding proteins.

Comparative RNA-Seq Analysis Revealed Tissue-Specific Splicing Variations during the Generation of the PDX Model

Tissue-specific gene expression generates fundamental differences in the function of each tissue and affects the characteristics of the tumors that are created as a result. However, it is unclear how much the tissue specificity is conserved during grafting of the primary tumor into an immune-compromised mouse model. Here, we performed a comparative RNA-seq analysis of four different primary-patient derived xenograft (PDX) tumors. The analysis revealed a conserved RNA biotype distribution of primary-PDX pairs, as revealed by previous works. Interestingly, we detected significant changes in the splicing pattern of PDX, which was mainly comprised of skipped exons. This was confirmed by splicing variant-specific RT-PCR analysis. On the other hand, the correlation analysis for the tissue-specific genes indicated overall strong positive correlations between the primary and PDX tumor pairs, with the exception of gastric cancer cases, which showed an inverse correlation. These data propose a tissue-specific change in splicing events during PDX formation as a variable factor that affects primary-PDX integrity.

Regulation of Epithelial-Mesenchymal Transitions by Alternative Splicing: Potential New Area for Cancer Therapeutics

The epithelial-mesenchymal transition (EMT) is a complicated biological process in which cells with epithelial phenotype are transformed into mesenchymal cells with loss of cell polarity and cell-cell adhesion and gain of the ability to migrate. EMT and the reverse mesenchymal-epithelial transitions (METs) are present during cancer progression and metastasis. Using the dynamic switch between EMT and MET, tumour cells can migrate to neighbouring organs or metastasize in the distance and develop resistance to traditional chemotherapy and targeted drug treatments. Growing evidence shows that reversing or inhibiting EMT may be an advantageous approach for suppressing the migration of tumour cells or distant metastasis. Among different levels of modulation of EMT, alternative splicing (AS) plays an important role. An in-depth understanding of the role of AS and EMT in cancer is not only helpful to better understand the occurrence and regulation of EMT in cancer progression, but also may provide new therapeutic strategies. This review will present and discuss various splice variants and splicing factors that have been shown to play a crucial role in EMT.

Role of CD44 isoforms in epithelial-mesenchymal plasticity and metastasis

Cellular plasticity lies at the core of cancer progression, metastasis, and resistance to treatment. Stemness and epithelial-mesenchymal plasticity in cancer are concepts that represent a cancer cell's ability to coopt and adapt normal developmental programs to promote survival and expansion. The cancer stem cell model states that a small subset of cancer cells with stem cell-like properties are responsible for driving tumorigenesis and metastasis while remaining especially resistant to common chemotherapeutic drugs. Epithelial-mesenchymal plasticity describes a cancer cell's ability to transition between epithelial and mesenchymal phenotypes which drives invasion and metastasis. Recent research supports the existence of stable epithelial/mesenchymal hybrid phenotypes which represent highly plastic states with cancer stem cell characteristics. The cell adhesion molecule CD44 is a widely accepted marker for cancer stem cells, and it lies at a functional intersection between signaling networks regulating both stemness and epithelial-mesenchymal plasticity. CD44 expression is complex, with alternative splicing producing many isoforms. Interestingly, not only does the pattern of isoform expression change during transitions between epithelial and mesenchymal phenotypes in cancer, but these isoforms have distinct effects on cell behavior including the promotion of metastasis and stemness. The role of CD44 both downstream and upstream of signaling pathways regulating epithelial-mesenchymal plasticity and stemness make this protein a valuable target for further research and therapeutic intervention.

CD44: A Multifunctional Mediator of Cancer Progression

CD44, a non-kinase cell surface transmembrane glycoprotein, has been widely implicated as a cancer stem cell (CSC) marker in several cancers. Cells overexpressing CD44 possess several CSC traits, such as self-renewal and epithelial-mesenchymal transition (EMT) capability, as well as a resistance to chemo- and radiotherapy. The CD44 gene regularly undergoes alternative splicing, resulting in the standard (CD44s) and variant (CD44v) isoforms. The interaction of such isoforms with ligands, particularly hyaluronic acid (HA), osteopontin (OPN) and matrix metalloproteinases (MMPs), drive numerous cancer-associated signalling. However, there are contradictory results regarding whether high or low CD44 expression is associated with worsening clinicopathological features, such as a higher tumour histological grade, advanced tumour stage and poorer survival rates. Nonetheless, high CD44 expression significantly contributes to enhanced tumourigenic mechanisms, such as cell proliferation, metastasis, invasion, migration and stemness; hence, CD44 is an important clinical target. This review summarises current research regarding the different CD44 isoform structures and their roles and functions in supporting tumourigenesis and discusses CD44 expression regulation, CD44-signalling pathways and interactions involved in cancer development. The clinical significance and prognostic value of CD44 and the potential of CD44 as a therapeutic target in cancer are also addressed.

Beyond Colonoscopy: Exploring New Cell Surface Biomarkers for Detection of Early, Heterogenous Colorectal Lesions

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths among both men and women in the United States. Early detection and surgical removal of high-risk lesions in the colon can prevent disease from developing and spreading. Despite implementation of programs aimed at early detection, screening colonoscopies fail to detect a fraction of potentially aggressive colorectal lesions because of their location or nonobvious morphology. Optical colonoscopies, while highly effective, rely on direct visualization to detect changes on the surface mucosa that are consistent with dysplasia. Recent advances in endoscopy techniques and molecular imaging permit microscale visualization of the colonic mucosa. These technologies can be combined with various molecular probes that recognize and target heterogenous lesion surfaces to achieve early, real-time, and potentially non-invasive, detection of pre-cancerous lesions. The primary goal of this review is to contextualize existing and emergent CRC surface biomarkers and assess each’s potential as a candidate marker for early marker-based detection of CRC lesions. CRC markers that we include were stratified by the level of support gleaned from peer-reviewed publications, abstracts, and databases of both CRC and other cancers. The selected biomarkers, accessible on the cell surface and preferably on the luminal surface of the colon tissue, are organized into three categories: (1) established biomarkers (those with considerable data and high confidence), (2) emerging biomarkers (those with increasing research interest but with less supporting data), and (3) novel candidates (those with very recent data, and/or supportive evidence from other tissue systems). We also present an overview of recent advances in imaging techniques useful for visual detection of surface biomarkers, and discuss the ease with which these methods can be combined with microscopic visualization.

CD44v3-Positive Intermediate Progenitor Cells Contribute to Airway Goblet Cell Hyperplasia

In allergic airway diseases, intermediate progenitor cells (IPCs) increase in number in the surface epithelium. IPCs arise from basal cells, the origin of hallmark pathological changes, including goblet cell hyperplasia and mucus hypersecretion. Thus, targeting IPCs will benefit future treatment of allergic airway diseases. However, the lack of adequate cell surface markers for IPCs limits their identification and characterization. We now show that CD44 containing exon v3 (CD44v3) is a surface marker for IPCs that are capable of both proliferating and generating differentiated goblet cells in allergic human nasal epithelium. In primary human nasal epithelial cells that had differentiated at an air-liquid interface, IL-4 upregulated mRNA expression of three CD44v variants that include exon v3 (CD44v3-v6, CD44v3,v8-v10, and CD44v3-v10), and it induced expression of CD44v3 protein in the basal and suprabasal layers of the culture. FACS analysis revealed two subpopulations differing in CD44v3 concentrations, as follows: CD44v3^low cells expressed high amounts of proliferative and basal cell markers (Ki-67 and TP63), whereas CD44v3^high cells strongly expressed progenitor and immature and mature goblet cell markers (SOX2, CA2, and SPDEF). Importantly, a blocking anti-CD44 antibody suppressed IL-4-induced mucin production by human nasal epithelial cells. Furthermore, CD44v3 was coexpressed with TP63, KRT5, or SOX2 and was upregulated in the basal and suprabasal layers of the nasal surface epithelium of subjects with allergic rhinitis. Taken together, these data demonstrate that high CD44v3 expression contributes to goblet cell hyperplasia in inflammation of the allergic airway.

The p53-induced RNA-binding protein ZMAT3 is a splicing regulator that inhibits the splicing of oncogenic CD44 variants in colorectal carcinoma

p53 is an intensely studied tumor-suppressive transcription factor. Recent studies suggest that the RNA-binding protein (RBP) ZMAT3 is important in mediating the tumor-suppressive effects of p53. Here, we globally identify ZMAT3-regulated RNAs and their binding sites at nucleotide resolution in intact colorectal cancer (CRC) cells. ZMAT3 binds to thousands of mRNA precursors, mainly at intronic uridine-rich sequences and affects their splicing. The strongest alternatively spliced ZMAT3 target was CD44, a cell adhesion gene and stem cell marker that controls tumorigenesis. Silencing ZMAT3 increased inclusion of CD44 variant exons, resulting in significant up-regulation of oncogenic CD44 isoforms (CD44v) and increased CRC cell growth that was rescued by concurrent knockdown of CD44v Silencing p53 phenocopied the loss of ZMAT3 with respect to CD44 alternative splicing, suggesting that ZMAT3-mediated regulation of CD44 splicing is vital for p53 function. Collectively, our findings uncover a p53-ZMAT3-CD44 axis in growth suppression in CRC cells.

Microenvironmentally-driven Plasticity of CD44 isoform expression determines Engraftment and Stem-like Phenotype in CRC cell lines

Theranostic biomarkers for putative cancer stem-like cells (CSC) in colorectal cancer (CRC) are of particular interest in translational research to develop patient-individualized treatment strategies. Surface proteins still under debate are CD44 and CD133. The structural and functional diversity of these antigens, as well as their plasticity, has only just begun to be understood. Our study aimed to gain novel insight into the plasticity of CD133/CD44, thereby proving the hypothesis of marker-associated tumorigenic and non-tumorigenic phenotypes to be environmentally driven.

Methods: CD133/CD44 profiles of 20 CRC cell lines were monitored; three models with distinct surface patterns in vitro were systematically examined. CD133/CD44 subpopulations were isolated by FACS and analyzed upon in vitro growth and/or in limiting dilution engraftment studies. The experimental setup included biomarker analyses on the protein (flow cytometry, Western blotting, immunofluorescence) and mRNA levels (RT-/qPCR) as well as CD44 gene sequencing.

Results: In general, we found that (i) the in vitro CD133/CD44 pattern never determined engraftment and (ii) the CD133/CD44 population distributions harmonized under in vivo conditions. The LS1034 cell line appeared as a unique model due to its de novo in vivo presentation of CD44. CD44v8-10 was identified as main transcript, which was stronger expressed in primary human CRC than in normal colon tissues. Biomarker pattern of LS1034 cells in vivo reflected secondary engraftment: the tumorigenic potential was highest in CD133⁺/CD44⁺, intermediate in CD133⁺/CD44^- and entirely lost in CD133^-/CD44^- subfractions. Both CD44⁺ and CD44^- LS1034 cells gave rise to tumorigenic and non-tumorigenic progeny and were convertible - but only as long as they expressed CD133 in vivo. The highly tumorigenic CD133⁺/CD44(v8-10)⁺ LS1034 cells were localized in well-oxygenated perivascular but not hypoxic regions. From a multitude of putative modulators, only the direct interaction with stromal fibroblasts triggered an essential, in vivo-like enhancement of CD44v8-10 presentation in vitro.

Conclusion: Environmental conditions modulate CD133/CD44 phenotypes and tumorigenic potential of CRC subpopulations. The identification of fibroblasts as drivers of cancer-specific CD44 expression profile and plasticity sheds light on the limitation of per se dynamic surface antigens as biomarkers. It can also explain the location of putative CD133/CD44-positive CRC CSC in the perivascular niche, which is likely to comprise cancer-associated fibroblasts. The LS1034 in vitro/in vivo model is a valuable tool to unravel the mechanism of stromal-induced CD44v8-10 expression and identify further therapeutically relevant, mutual interrelations between microenvironment and tumorigenic phenotype.

Cucurbitacin B and I inhibits colon cancer growth by targeting the Notch signaling pathway

Cancer stem cells (CSCs) have the ability to self-renew and induce drug resistance and recurrence in colorectal cancer (CRC). As current chemotherapy doesn’t eliminate CSCs completely, there is a need to identify novel agents to target them. We investigated the effects of cucurbitacin B (C-B) or I (C-I), a natural compound that exists in edible plants (bitter melons, cucumbers, pumpkins and zucchini), against CRC. C-B or C-I inhibited proliferation, clonogenicity, induced G₂/M cell-cycle arrest and caspase-mediated-apoptosis of CRC cells. C-B or C-I suppressed colonosphere formation and inhibited expression of CD44, DCLK1 and LGR5. These compounds inhibited notch signaling by reducing the expression of Notch 1–4 receptors, their ligands (Jagged 1-2, DLL1,3,4), γ-secretase complex proteins (Presenilin 1, Nicastrin), and downstream target Hes-1. Molecular docking showed that C-B or C-I binds to the ankyrin domain of Notch receptor, which was confirmed using the cellular thermal shift assay. Finally, C-B or C-I inhibited tumor xenograft growth in nude mice and decreased the expression of CSC-markers and notch signaling proteins in tumor tissues. Together, our study suggests that C-B and C-I inhibit colon cancer growth by inhibiting Notch signaling pathway.

Systematic analysis of survival-associated alternative splicing signatures in clear cell renal cell carcinoma

Alternative splicing (AS) constitutes a major reason for messenger RNA (mRNA) and protein diversity. Increasing studies have shown a link to splicing dysfunction associated with malignant neoplasia. Systematic analysis of AS events in kidney cancer remains poorly reported. Therefore, we generated AS profiles in 533 kidney renal clear cell carcinoma (KIRC) patients in The Cancer Genome Atlas (TCGA) database using RNA-seq data. Then, prognostic models were developed in a primary cohort (N = 351) and validated in a validation cohort (N = 182). In addition, splicing networks were built by integrating bioinformatics analyses. A total of 11 268 and 8083 AS variants were significantly associated with patient overall survival time in the primary and validation KIRC cohorts, respectively, including STAT1, DAZAP1, IDS, NUDT7, and KLHDC4. The AS events in the primary KIRC cohorts served as candidate AS events to screen the independent risk factors associated with survival in the primary cohort and to develop prognostic models. The area under the curve of the receiver-operator characteristic curve for prognostic prediction in the primary and validation KIRC cohorts was 0.84 and 0.82 at 2500 days of overall survival, respectively. In addition, splicing correlation networks revealed key splicing factors (SFs) in KIRC, such as HNRNPH1, HNRNPU, KHDBS1, KHDBS3, SRSF9, RBMX, SFQ, SRP54, HNRNPA0, and SRSF6. In this study, we analyzed the AS landscape in the TCGA KIRC cohort and detected predictors (prognostic) based on AS variants with high performance for risk stratification of the KIRC cohort and revealed key SFs in splicing networks, which could act as underlying mechanisms.

CD44 splice variant (CD44v3) promotes progression of urothelial carcinoma of bladder through Akt/ERK/STAT3 pathways: novel therapeutic approach

PURPOSE

The incidence of Urothelial carcinoma of bladder (UBC) is gradually increasing by changing lifestyle and environment. The development of a tumor has been noted to be accompanied by modifications in the extracellular matrix (ECM) consisting of CD44, hyaluronic acid (HA) and its family members. The importance of CD44 splice variants and HA family members has been studied in UBC.

METHODS

The cohort of study included 50 UBC patients undergoing radical cystectomy and 50 healthy subjects. The molecular expression of CD44 and HA family members was determined. Effect of CD44 variant-specific silencing on downstream signaling in HT1376 cells was investigated. Combinatorial treatment of 4-MU (4-methylumbelliferone) with cisplatin or doxorubicin on chemosensitivity was also explored.

RESULTS

Higher expression of HA, HAS2, and CD44 was observed in Indian UBC patients which also showed the trend with severity of disease. Splice variant assessment of CD44 demonstrated the distinct role of CD44v3 and CD44v6 in bladder cancer progression. shRNA-mediated downregulation of CD44v3 showed an increase effect on cell cycle, apoptosis and multiple downstream signaling cascade including pAkt, pERK and pSTAT3. Furthermore, 4-MU, an HA synthesis inhibitor, observed to complement the effect of Cisplatin or Doxorubicin by enhancing the chemosensitivity of bladder cancer cells.

CONCLUSIONS

Our findings exhibit involvement of CD44 splice variants and HA family members in UBC and significance of 4-MU in enhancing chemosensitivity suggesting their novel therapeutic importance in disease therapeutics.

Is the non-metastatic, locally advanced colon adenocarinoma a distinct biological tumor variant? A study based on pathological evaluation, immunohistochemical panel and survival

OBJECTIVE

to evaluate the clinical and pathological differences between locally advanced colonic adenocarcinomas (LACA) with adhesions between adjacent organs or structures, and colonic adenocarcinomas with other clinical presentations.

METHODS

we conducted a retrospective study from a convenience sample of patients with colonic adenocarcinoma, pathological stage pT3, distributed according to clinical and pathological characteristics in three groups: locally advanced tumors (LACA), pT3 tumors without adhesions or distant metastases (SF) and tumors with metastatic disease (M1). We evaluated clinical and pathological characteristics and the expression of seven immunohistochemical markers related to proliferation/apoptosis, cell invasion/migration and metastasis.

RESULTS

we studied 101 patients: 30 LACA, 44 SF and 27 M1. Locally advanced tumors presented larger dimensions and were associated with increased lymphocyte infiltration rates, lower levels of bax expression, and CD 44v6 when compared with SF and M1 groups. We observed significant differences between LACA and M1 in relation to colonic location, histology, lymph node status and bax and CD44v6 expression. We found differences were observed between the three groups for tumor size and lymphocytic infiltrate. Survival was similar in the LACA and SF groups (p=0.66) and was lower in the M1 group (p<0.001).

CONCLUSION

the data suggest that locally advanced colonic adenocarcinomas with adhesions between adjacent organs or structures represent a distinct entity.

Inducible formation of leader cells driven by CD44 switching gives rise to collective invasion and metastases in luminal breast carcinomas

Collective invasion into adjacent tissue is a hallmark of luminal breast cancer, and ~20% of these cases eventually undergo metastasis. How less aggressive luminal-like breast cancer transitions to invasive cancer remains unclear. Our study revealed that CD44^hi cancer cells are the leading subpopulation in collectively invading luminal cancer cells and efficiently promote the collective invasion of CD44^lo/follower cells. The CD44^hi/leader subpopulation showed a specific gene signature of various hybrid epithelial/mesenchymal genes and key functional coregulators of collective invasion, which was distinct from that of CD44^lo/follower cells. However, the CD44^hi/leader cells, which showed a partial epithelial-mesenchymal transition (EMT) phenotype, readily switched to the CD44^lo phenotype along with collective migration and vice versa; this phenomenon was spontaneous and sensitive to the tumor microenvironment. The CD44^lo-to-CD44^hi conversion was accompanied by a shift in CD44s to CD44v but not a conversion of non-cancer stem cells to cancer stem cells (CSCs). Therefore, the CD44^hi leader cells, as currently identified, are not a stable subpopulation in breast tumors. This plasticity and ability to generate CD44^hi carcinoma cells with enhanced migratory and invasive behavior might be responsible for the transition from in situ to invasive behavior of luminal-type breast cancer.

O-GlcNAcylation Is Involved in the Regulation of Stem Cell Markers Expression in Colon Cancer Cells

The dynamic O-linked-N-acetylglucosamine posttranslational modification of nucleocytoplasmic proteins has emerged as a key regulator of diverse cellular processes including several hallmarks of cancer. However, the role played by this modification in the establishment of CSC phenotype has been poorly studied so far and remains unclear. In this study we confirmed the previous reports showing that colon cancer cells exhibit higher O-GlcNAc basal levels than non-malignant cells, and investigated the role played by O-GlcNAcylation in the regulation of CSC phenotype. We found that the modification of O-GlcNAcylation levels by pharmacological inhibition of the O-GlcNAc-transferase enzyme that adds O-GlcNAc (OGT), but not of the enzyme that removes it (OGA), increased the expression of all stem cell markers tested in our colon malignant cell lines, and induced the appearance of a double positive (CD44+/CD133+) small stem cell-like subpopulation (which corresponded to 1-10%) that displayed very aggressive malignant phenotype such as increased clonogenicity and spheroid formation abilities in 3D culture. We reasoned that OGT inhibition would mimic in the tumor the presence of severe nutritional stress, and indeed, we demonstrated that nutritional stress reproduced in colon cancer cells the effects obtained with OGT inhibition. Thus, our data strongly suggests that stemness is regulated by HBP/O-GlcNAcylation nutrient sensing pathway, and that O-GlcNAc nutrient sensor represents an important survival mechanism in cancer cells under nutritional stressful conditions.

Nanoparticulate photosensitizer decorated with hyaluronic acid for photodynamic/photothermal cancer targeting therapy

AIM

A photomedicine consisting of a core for photothermal therapy, a photosensitizer for photodynamic therapy, and a cancer-targeting moiety was fabricated to improve photosensitizer selectivity and antitumor efficiency.

MATERIALS & METHODS

Hyaluronic acid-decorated polydopamine nanoparticles with conjugated chlorin e6 (HA-PDA-Ce6) were synthesized and characterized. Cell uptake, phototoxicity, penetration, distribution and therapeutic effects were evaluated.

RESULTS

HA-PDA-Ce6 had high photoactivities for photodynamic therapy/photothermal therapy and was readily internalized via CD44-mediated endocytosis. Enhanced accumulation and deeper penetration into tumors were achieved by the diffusion molecular retention tumor targeting effect following peritumoral injection. In the combination therapy, HA-PDA-Ce6 displayed the highest tumor growth inhibition in HCT-116 tumor-bearing mice.

CONCLUSION

HA-PDA-Ce6 is promising for targeted colorectal cancer therapy.

Silibinin, A Natural Blend In Polytherapy Formulation For Targeting Cd44v6 Expressing Colon Cancer Stem Cells

Colon cancer stem cells have been attributed to poor prognosis, therapeutic resistance and aggressive nature of the malignancy. Recent reports associated CD44v6 expression with relapse, metastasis and reduced 5-year survival of colon cancer patients, thereby making it a potential therapeutic target. Thus, in this study, comprehensive prediction and screening of CD44v6 against 1674 lead compounds was conducted. Silibinin was identified as a potential compound targeting CD44v6. Inorder to substantiate these findings, the cytotoxic effect of 5FU, Silibinin and 5FU+ Silibinin was assessed on human colon carcinoma cell line HCT116 derived CD44+ subpopulation. 5FU+ Silibinin inhibited cell proliferation of CD44+ subpopulation at lower concentration than Silibinin standalone. Further, corresponding to CD44v6 knockdown cells, 5FU+ Silibinin treatment significantly decreased CD44v6, Nanog, CTNNB1 and CDKN2A expression whereas increased E-cadherin expression in HCT116 derived CD44+ cells. Moreover, synergistic effect of these drugs suppressed sphere formation, inhibited cell migration, triggered PARP cleavage and perturbation in mitochondrial membrane potential, thereby activating intrinsic apoptotic pathways and induced autophagic cell death. Importantly, 5FU+ Silibinin could inhibit PI3K/MAPK dual activation and arrest the cell cycle at G0/G1 phase. Thus, our study suggests that inhibition of CD44v6 attenuates stemness of colon cancer stem cells and holds a prospect of potent therapeutic target.

The loss of CD44 and HSP70 overexpression is related to aggressive clinicopathologic factors in prostate cancer

Prostate cancer (PC) is the most common cancer in men with biologically highly heterogeneous clinical outcomes despite early detection. Therefore, the identification of novel molecular markers that are associated with biological aggressiveness is essential for predicting clinical outcomes and deciding the treatment of PC. We examined the expression of cluster of differentiation 44 (CD44) and heat shock protein 70 (HSP70) in PC cells using immunohistochemistry on tissue microarrays and evaluated their clinicopathological significance. A loss of CD44 expression and HSP70 overexpression were observed in 62 (57.9%) and 54 (50.5%) out of 107 cases of PC, respectively. CD44-negative PC showed more vascular invasion, more extra-prostatic extension, more capsular invasion, higher pT stages, higher pathological tumor stages, higher prostate-specific antigen levels (> 20 ng/mL), and higher grades groups. Overexpression of HSP70 was significantly associated with PC with capsular invasion, higher pT stages, and higher pathological tumor stages. The loss of CD44 expression is correlated with tumor invasiveness and higher Gleason grades, reflecting the features of aggressive tumors. Consequently, CD44 could be an important biomarker and a potential therapeutic target.

Enzymatically synthesized poly(amino-co-ester) polyplexes for systemic delivery of pcDNA-miRNA-214 to suppress colorectal cancer liver metastasis

Liver metastases from colorectal cancer (CRC) are the major cause of cancer-related deaths in CRC patients. In our previous study, microRNA-214 (miR-214) was identified in CRC patients as a novel regulator of CRC liver metastasis, which could serve as a therapeutic target to inhibit CRC proliferation and metastasis. In this study, we aim to develop a new CRC treatment strategy based on miR-214 gene therapy using biodegradable non-viral gene vectors. We developed multifunctional quaternary polyplexes that consist of cationic poly(ω-pentadecalactone-co-N-methyldiethyleneamine-co-sebacate) (PPMS) for DNA condensation to form a nano-sized polyplex core, hyaluronic acids (HA) grafted with a poly(ethylene glycol) (PEG) (HA-g-mPEG) shell for polyplex stabilization and targeted delivery, and nuclear localization signal (NLS) peptides for enhanced intracellular transport of pDNA to the nucleus. The results showed that the DNA/NLS/PPMS/HA-g-mPEG quaternary polyplexes could enhance DNA condensation, increase cellular uptake efficiency and decrease cytotoxicity. Most importantly, the quaternary polyplexes showed favorable transfection efficiency both in vitro and in vivo. The colony formation and migration ability were significantly inhibited in HCT116 cells transfected with pcDNA-miR-214 quaternary polyplexes. The up-regulation of miR-214 in HCT116 cells by pre-transfection of polyplexes-miR-214 could remarkably inhibit tumor growth and liver metastases in a xenograft mouse model. Furthermore, systemic administration of miR-214 using this multifunctional vector resulted in dramatic inhibition of liver metastasis without obvious toxicity in CRC xenografted mice. Collectively, systemic delivery of pcDNA-miR-214 by this multifunctional vector could be a powerful and highly specific therapeutic approach in the treatment of CRC liver metastasis.

Melanoma differentiation-associated gene-7 suppresses human gastric cancer cell invasion and migration

Gastric cancer is one of the most common types of cancer in the world. Patients with gastric cancer often respond poorly to conventional chemotherapies, therefore more comprehensive therapy is required. Melanoma differentiation-associated gene-7 (MDA-7), also termed interleukin-24, is a potent tumor suppressor gene. Numerous studies have demonstrated that MDA-7 suppresses the growth and induces the apoptosis of cancer cells. In the present study, the MDA-7 gene was transfected into human gastric cancer AGS cells using adenovirus. Transwell and wound healing assays were performed to evaluate AGS cell invasion and migration, respectively. Western blotting was used to detect the expression of epithelial (E)-cadherin, cluster of differentiation (CD)44 and matrix metalloproteinase (MMP)-2 and MMP-9 proteins. A recombinant virus package was successfully constructed, and it was verified using western blotting that exogenous MDA-7 was highly expressed in the AGS cells. MDA-7 overexpression inhibited invasion and migration, decreased CD44, MMP-2 and MMP-9 expression, and increased epithelial (E-)cadherin expression in the AGS cells. Results of the present study revealed that MDA-7 inhibits gastric cancer invasion and metastasis by inhibiting CD44, MMP-2 and MMP-9 expression and by promoting E-cadherin expression.

Drug resistance related to aberrant glycosylation in colorectal cancer

Colorectal cancer (CRC) is the fourth leading cause of cancer-related deaths in the world. Drug resistance of tumour cells remains the main challenge toward curative treatments efficiency. Several epidemiologic studies link emergence and recurrence of this cancer to metabolic disorders. Glycosylation that modifies more than 80% of human proteins is one of the most widepread nutrient-sensitive post-translational modifications. Aberrant glycosylation participates in the development and progression of cancer. Thus, some of these glycan changes like carbohydrate antigen CA 19-9 (sialyl Lewis a, sLea) or those found on carcinoembryonic antigen (CEA) are already used as clinical biomarkers to detect and monitor CRC. The current review highlights emerging evidences accumulated mainly during the last decade that establish the role played by altered glycosylations in CRC drug resistance mechanisms that induce resistance to apoptosis and activation of signaling pathways, alter drug absorption and metabolism, and led to stemness acquisition. Knowledge in this field of investigation could aid to the development of better therapeutic approaches with new predictive biomarkers and targets tied in with adapted diet.

Next-generation sequencing: recent applications to the analysis of colorectal cancer

Since the establishment of the Sanger sequencing method, scientists around the world focused their efforts to progress in the field to produce the utmost technology. The introduction of next-generation sequencing (NGS) represents a revolutionary step and promises to lead to massive improvements in our understanding on the role of nucleic acids functions. Cancer research began to use this innovative and highly performing method, and interesting results started to appear in colorectal cancer (CRC) analysis. Several studies produced high-quality data in terms of mutation discovery, especially about actionable or less frequently mutated genes, epigenetics, transcriptomics. Analysis of results is unveiling relevant perspectives aiding to evaluate the response to therapies. Novel evidences have been presented also in other directions such as gut microbiota or CRC circulating tumor cells. However, despite its unquestioned potential, NGS poses some issues calling for additional studies. This review intends to offer a view of the state of the art of NGS applications to CRC through examination of the most important technologies and discussion of recent published results.

CD44v8-10 as a potential theranostic biomarker for targeting disseminated cancer cells in advanced gastric cancer

Gastric cancer is the third most common cause of cancer mortality, and the survival rate of stage IV advanced gastric cancer (AGC) patients with distant metastasis is very low. Thus, the detection and eradication of disseminated cancer cells by targeting cell surface molecules in AGC would improve patient survival. The hyaluronic acid receptor, CD44, has various isoforms generated by alternative splicing, and some isoforms are known to be correlated to gastric cancer. In this study, to find out the most appropriate CD44v for targeting AGC, we analysed the expression differences of CD44 isoforms at the mRNA level in stomach cancer cell lines as well as in 74 patients with AGC by using exon-specific qRT-PCR. Among the CD44v isoforms, CD44v8-10 was determined as the most promising biomarker for the development of theranostic agents of gastric cancer. Next, we synthesised the conjugate of anti-CD44v9 antibody with near-infrared fluorophore or photosensitiser, and then demonstrated its feasibility for target cell-specific imaging and photoimmunotherapy in gastric cancer. As a result, these conjugates have clearly demarcated the surface of CD44v8-10 expressing cancer cells and showed efficient phototoxic effects. Therefore, this study revealed that CD44v8-10 is the efficient theranostic biomarker to target disseminated cancer cells in AGC.

Chitosan/Hyaluronic Acid Nanoparticles: Rational Design Revisited for RNA Delivery

Chitosan/hyaluronic acid (HA) nanoparticles can be used to deliver an RNA/DNA cargo to cells overexpressing HA receptors such as CD44. For these systems, unequivocal links have not been established yet between chitosan macromolecular (molecular weight; degree of deacetylation, i.e., charge density) and nanoparticle variables (complexation strength, i.e., stability; nucleic acid protection; internalization rate) on one hand, and transfection efficiency on the other hand. Here, we have focused on the role of avidity on transfection efficiency in the CD44-expressing HCT-116 as a cellular model; we have employed two differently sized payloads (a large luciferase-encoding mRNA and a much smaller anti-Luc siRNA), and a small library of chitosans (variable molecular weight and degree of deactylation). The RNA avidity for chitosan showed-as expected-an inverse relationship: higher avidity-higher polyplex stability-lower transfection efficiency. The avidity of chitosan for RNA appears to lead to opposite effects: higher avidity-higher polyplex stability but also higher transfection efficiency. Surprisingly, the best transfecting particles were those with the lowest propensity for RNA release, although this might be a misleading relationship: for example, the same macromolecular parameters that increase avidity can also boost chitosan's endosomolytic activity, with a strong enhancement in transfection. The performance of these nonviral vectors appears therefore difficult to predict simply on the basis of carrier- or payload-related variables, and a more holistic consideration of the journey of the nanoparticle, from cell uptake to cytosolic bioavailability of payload, is needed. It is also noteworthy that the nanoparticles used in this study showed optimal performance under slightly acidic conditions (pH 6.4), which is promising for applications in a tumoral extracellular environment. It is also worth pointing out that under these conditions we have for the first time successfully delivered mRNA with chitosan/HA nanoparticles.

A marine bio-functional lipid, fucoxanthinol, attenuates human colorectal cancer stem-like cell tumorigenicity and sphere formation

Fucoxanthinol (FuOH), an intestinal metabolite form of fucoxanthin (Fx) isolated from marine algae, is known to possess multiple health benefits, such as prevention of human cancer. However, there is little available information about the effects of FuOH on colorectal cancer stem cells (CCSCs) and their contribution to drug resistance, tumorigenesis and cancer recurrence. In the present study, we investigated the anti-proliferative effect of FuOH on two putative CCSCs, CD44^high/EpCAM^high cells and colonospheres (Csps) formed by HT-29 human colorectal cancer cells, and the suppressive effects of FuOH on the growth of xenografted tumor. FuOH significantly inhibited the growth of CD44^high/EpCAM^high cells and disintegrated Csps and induced many condensed chromatin bodies in the cells in a dose-dependent manner. The IC₅₀ value of FuOH for these changes in Csps was 1.8 µM. FuOH down-regulated pAkt (Ser⁴⁷³), PPARβ/δ and PPARγ in Csps. These proteins play a critical role in cell proliferation, the cell cycle, metastasis and extracellular adhesion. Ten days after the administration of FuOH (5 mg/kg body weight) to the mice every 3 to 4 days significantly suppressed the Csps tumorigenesis when compared to the untreated control mice. Our results suggest that FuOH could be used as a chemopreventive agent against human CCSC.

Self-renewal molecular mechanisms of colorectal cancer stem cells

Colorectal cancer stem cells (CCSCs) represent a small fraction of the colorectal cancer cell population that possess self-renewal and multi-lineage differentiation potential and drive tumorigenicity. Self-renewal is essential for the malignant biological behaviors of colorectal cancer stem cells. While the self-renewal molecular mechanisms of colorectal cancer stem cells are not yet fully understood, the aberrant activation of signaling pathways, such as Wnt, Notch, transforming growth factor-β (TGF-β)/bone morphogenetic protein (BMP) and Hedgehog-Gli (HH-GLI), specific roles mediated by cell surface markers and micro-environmental factors are involved in the regulation of self-renewal. The elucidation of the molecular mechanisms behind self-renewal may lead to the development of novel targeted interventions for the treatment of colorectal cancer.

Overexpression of Specific CD44 Isoforms Is Associated with Aggressive Cell Features in Acquired Endocrine Resistance

While endocrine therapy is the mainstay of ER+ breast cancer, the clinical effectiveness of these agents is limited by the phenomenon of acquired resistance that is associated with disease relapse and poor prognosis. Our previous studies revealed that acquired resistance is accompanied by a gain in cellular invasion and migration and also that CD44 family proteins are overexpressed in the resistant phenotype. Given the association of CD44 with tumor progression, we hypothesized that its overexpression may act to promote the aggressive behavior of endocrine-resistant breast cancers. Here, we have investigated further the role of two specific CD44 isoforms, CD44v3 and CD44v6, in the endocrine-resistant phenotype. Our data revealed that overexpression of CD44v6, but not CD44v3, in endocrine-sensitive MCF-7 cells resulted in a gain in EGFR signaling, enhanced their endogenous invasive capacity, and attenuated their response to endocrine treatment. Suppression of CD44v6 in endocrine-resistant cell models was associated with a reduction in their invasive capacity. Our data suggest that upregulation of CD44v6 in acquired resistant breast cancer may contribute to a gain in the aggressive phenotype of these cells and loss of endocrine response through transactivation of the EGFR pathway. Future therapeutic targeting of CD44v6 may prove to be an effective strategy alongside EGFR-targeted agents in delaying/preventing acquired resistance in breast cancer.

Chronic chemotherapeutic stress promotes evolution of stemness and WNT/beta-catenin signaling in colorectal cancer cells: implications for clinical use of WNT-signaling inhibitors

Most solid tumors contain a subfraction of cells with stem/progenitor cell features. Stem cells are naturally chemoresistant suggesting that chronic chemotherapeutic stress may select for cells with increased “stemness”. We carried out a comprehensive molecular and functional analysis of six independently selected colorectal cancer (CRC) cell lines with acquired resistance to three different chemotherapeutic agents derived from two distinct parental cell lines. Chronic drug exposure resulted in complex alterations of stem cell markers that could be classified into three categories: 1) one cell line, HT-29/5-FU, showed increased “stemness” and WNT-signaling, 2) three cell lines showed decreased expression of stem cell markers, decreased aldehyde dehydrogenase activity, attenuated WNT-signaling and lost the capacity to form colonospheres and 3) two cell lines displayed prominent expression of ABC transporters with a heterogeneous response for stem cell markers. While WNT-signaling could be attenuated in the HT-29/5-FU cells by the WNT-signaling inhibitors ICG-001 and PKF-118, this was not accompanied by any selective growth inhibitory effect suggesting that the cytotoxic activity of these compounds is not directly linked to WNT-signaling inhibition. We conclude that classical WNT-signaling inhibitors have toxic off-target activities that need to be addressed for clinical development.

Selective killing of breast cancer cells expressing activated CD44 using CD44 ligand-coated nanoparticles in vitro and in vivo

The cell surface glycoprotein CD44 is expressed in cancer cells and has been used as a therapeutic target in preclinical studies. However, the ubiquitous expression of CD44 in numerous cell types, including hematopoietic cells, has hindered its application in targeted therapy. Here, we demonstrated that CD44 was activated on breast cancer cells but was inactive on normal cells in vitro and in vivo. We analyzed 34 clinical primary tumor and normal breast tissues and demonstrated that CD44 was in an active state on breast cancer cells but in an inactive state on normal cells. Furthermore, based on the binding property of CD44 with its ligand hyaluronan (HA), we self-assembled HA-coated nanoparticles and studied their selective targeting efficacy. Our results indicate that HA-coated nanoparticles bearing the CD44 ligand selectively targeted cancer cells both in vitro and in vivo, killing breast cancer cells while sparing normal cells. Our study suggested that the active state of CD44 plays a crucial role in the selective targeting of breast cancer cells by avoiding nonspecific toxicity to CD44-quiescent normal cells. These findings may provide a new idea for the selective targeting of cancer cells in other human cancers.

Identification of Alternative Splicing and Fusion Transcripts in Non-Small Cell Lung Cancer by RNA Sequencing

Background

Lung cancer is the most common cause of cancer related death. Alterations in gene sequence, structure, and expression have an important role in the pathogenesis of lung cancer. Fusion genes and alternative splicing of cancer-related genes have the potential to be oncogenic. In the current study, we performed RNA-sequencing (RNA-seq) to investigate potential fusion genes and alternative splicing in non-small cell lung cancer.

Methods

RNA was isolated from lung tissues obtained from 86 subjects with lung cancer. The RNA samples from lung cancer and normal tissues were processed with RNA-seq using the HiSeq 2000 system. Fusion genes were evaluated using Defuse and ChimeraScan. Candidate fusion transcripts were validated by Sanger sequencing. Alternative splicing was analyzed using multivariate analysis of transcript sequencing and validated using quantitative real time polymerase chain reaction.

Results

RNA-seq data identified oncogenic fusion genes EML4-ALK and SLC34A2-ROS1 in three of 86 normal-cancer paired samples. Nine distinct fusion transcripts were selected using DeFuse and ChimeraScan; of which, four fusion transcripts were validated by Sanger sequencing. In 33 squamous cell carcinoma, 29 tumor specific skipped exon events and six mutually exclusive exon events were identified. ITGB4 and PYCR1 were top genes that showed significant tumor specific splice variants.

Conclusion

In conclusion, RNA-seq data identified novel potential fusion transcripts and splice variants. Further evaluation of their functional significance in the pathogenesis of lung cancer is required.

Progress in research of colorectal intraepithelial neoplasia and adenoma

Colorectal cancer is a common malignant tumor in the digestive system, and the early diagnosis of colorectal cancer has been the focus of its prevention and control. Colorectal intraepithelial neoplasia and adenoma are considered to be the most important precancerous lesions of colorectal cancer. In recent years, with the development of biological medicine, genetics,

and other disciplines, many studies have explored the relationship between intraepithelial neoplasia and adenoma and colorectal cancer, and some new research progress has been achieved to provide some guidance for the future clinical screening, regular follow-up and chemical prevention. However, it remains to be studied how colorectal intraepithelial neoplasia and adenoma form and evolve to colorectal cancer.

Concise Review: Emerging Role of CD44 in Cancer Stem Cells: A Promising Biomarker and Therapeutic Target

The reception and integration of the plethora of signals a cell receives from its microenvironment determines the cell's fate. CD44 functions as a receptor for hyaluronan and many other extracellular matrix components, as well as a cofactor for growth factors and cytokines, and thus, CD44 is a signaling platform that integrates cellular microenvironmental cues with growth factor and cytokine signals and transduces signals to membrane-associated cytoskeletal proteins or to the nucleus to regulate a variety of gene expression levels related to cell-matrix adhesion, cell migration, proliferation, differentiation, and survival. Accumulating evidence indicates that CD44, especially CD44v isoforms, are cancer stem cell (CSC) markers and critical players in regulating the properties of CSCs, including self-renewal, tumor initiation, metastasis, and chemoradioresistance. Furthermore, there is ample evidence that CD44, especially CD44v isoforms, are valuable prognostic markers in various types of tumors. Therefore, therapies that target CD44 may destroy the CSC population, and this holds great promise for the cure of life-threatening cancers. However, many challenges remain to determining how best to use CD44 as a biomarker and therapeutic target. Here we summarize the current findings concerning the critical role of CD44/CD44v in the regulation of cancer stemness and the research status of CD44/CD44v as biomarkers and therapeutic targets in cancer. We also discuss the current challenges and future directions that may lead to the best use of CD44/CD44v for clinical applications.

SIGNIFICANCE

Mounting evidence indicates that cancer stem cells (CSCs) are mainly responsible for cancer aggressiveness, drug resistance, and tumor relapse. CD44, especially CD44v isoforms, have been identified as CSC surface markers for isolating and enriching CSCs in different types of cancers. The current findings concerning the critical role of CD44/CD44v in regulation of cancer stemness and the research status of CD44/CD44v as biomarkers and therapeutic targets in cancer are summarized. The current challenges and future directions that may lead to best use of CD44/CD44v for clinical applications are also discussed.

Blocking the adhesion cascade at the premetastatic niche for prevention of breast cancer metastasis

Shear-resistant adhesion and extravasation of disseminated cancer cells at the target organ is a crucial step in hematogenous metastasis. We found that the vascular adhesion molecule E-selectin preferentially promoted the shear-resistant adhesion and transendothelial migration of the estrogen receptor (ER)(-)/CD44(+) hormone-independent breast cancer cells, but not of the ER(+)/CD44(-/low) hormone-dependent breast cancer cells. Coincidentally, CD44(+) breast cancer cells were abundant in metastatic lung and brain lesions in ER(-) breast cancer, suggesting that E-selectin supports hematogenous metastasis of ER(-)/CD44(+) breast cancer. In an attempt to prevent hematogenous metastasis through the inhibition of a shear-resistant adhesion of CD44(+) cancer cells to E-selectin-expressing blood vessels on the premetastatic niche, an E-selectin targeted aptamer (ESTA) was developed. We demonstrated that a single intravenous injection of ESTA reduced metastases to a baseline level in both syngeneic and xenogeneic forced breast cancer metastasis models without relocating the site of metastasis. The effect of ESTA was absent in E-selectin knockout mice, suggesting that E-selectin is a molecular target of ESTA. Our data highlight the potential application of an E-selectin antagonist for the prevention of hematogenous metastasis of ER(-)/CD44(+) breast cancer.

High expression of protein phosphatase 4 is associated with the aggressive malignant behavior of colorectal carcinoma

Background

Recent evidence suggests an important role of protein phosphatase 4 (PP4C) in the progression of several cancers, including breast cancer, lung cancer and pancreatic ductal adenocarcinoma. However, the contribution of PP4C to colorectal carcinoma (CRC) remains elusive.

Methods

The expression of PP4C in CRC tissues compared with matched non-tumor tissues and CRC cells was detected using quantitative RT-PCR, immunohistochemistry and western blotting assays. Through univariate and Kaplan-Meier analysis, we correlated the PP4C expression with clinicopathological features and patient survival. A series of experiments, including cell proliferation, lentiviral infection, cell invasion and MMP gelatinase activity assays, were performed to investigate the underlying mechanisms. Through further experiments, tumor growth and metastasis were evaluated in vivo using a xenogenous subcutaneously implant model and a tail vein metastasis model.

Results

In the present study, we found that PP4C expression is frequently increased in human CRC and that the upregulation of PP4C correlates with a more invasive tumor phenotype and poor prognosis. The ectopic expression of PP4C promoted CRC cell proliferation, migration and invasion in vitro and tumor growth and lung metastasis in vivo. Silencing the expression of PP4C resulted in the inhibition of cell proliferation and invasion. Further investigations showed that phosphorylated Akt (p-AKT) is required for the PP4C-mediated upregulation of MMP-2 and MMP-9, which promotes cell invasion.

Conclusions

Our data suggested a potential role of PP4C in tumor progression and provided novel insights into the mechanism of how this factor positively regulated cell proliferation and invasion in CRC cells.

CD44 Isoform Status Predicts Response to Treatment with Anti-CD44 Antibody in Cancer Patients

PURPOSE

CD44, a cell surface glycoprotein, plays important roles in the development, progression, and metastasis of various tumor types. The aim of this study was to investigate how the expression of CD44 isoforms influences the interaction with hyaluronic acid (HA) and how differential isoform expression impacts antitumoral responses in vivo to treatment with RG7356, a humanized anti-CD44 antibody inhibiting CD44-HA interaction.

EXPERIMENTAL DESIGN

CD44 isoform expression on various tumor cell lines was analyzed by RNASeq while data on patients with different tumor types were obtained from the publicly available TCGA RNASeq dataset as well as a phase I clinical study (NCT01358903). We analyzed the link between HA production and CD44 isoform expression as well as the consequences of blocking the CD44-mediated cell adhesion to HA using RG7356. The correlation between CD44 isoform expression and antitumor response to RG7356 treatment was investigated in the corresponding murine xenograft in vivo models as well as in a subset of patients treated with RG7356 from a recently completed phase I clinical trial.

RESULTS

CD44 isoform expression, in particular expression of CD44s, is associated with HA production and predicts response to treatment with RG7356 in tumor xenograft models. Furthermore, patient data suggest that CD44 isoform status is a potential predictive biomarker for clinical response to treatment with RG7356.

CONCLUSIONS

We provide new insights into the close interplay between CD44 and HA and a potential biomarker to enrich patient responses to RG7356 in the clinic.

Clinicopathological significance of CD133 and CD44 expression in infiltrating ductal carcinoma and their relationship to angiogenesis

BACKGROUND

Breast cancer is the leading cause of cancer death in females worldwide, and the majority type is infiltrating ductal carcinoma (IDC). Most of IDC patients died of metastasis and recurrence. Cancer stem cells (CSCs) are defined with the ability to be self-renewal and potentially promote proliferation and formation of tumors. CSCs are related to angiogenesis and are important targets in new cancer treatment strategies. In this study, we purposed to investigate on expression and clinical significances of CSCs marked by CD133 and CD44 in IDC and their relationship to angiogenesis.

METHODS

The specimens of IDC from 325 Chinese patients with follow-up were analyzed for CD133, CD44, CD82, and CD34 protein expression by immunohistochemical staining. The Pearson chi-square test and t test were used to assess the associations among the positive staining of these markers and clinicopathological characteristics. Postoperative overall survival time in these patients with IDC was analyzed by univariate and multivariate analyses.

RESULTS

In IDC tissues, positive rates of 48.6%, 53.8%, and 42.2% were obtained for CD133, CD44, and CD82 protein, respectively; the mean score of microvessel density (MVD) was 20.5 ± 7.0 in IDC group. And there was a significant difference between the two groups. There was a positive relationship between the expression of CD133, CD44, and the score of MVD and the grades of tumor, lymph node metastasis, tumor-node-metastasis (TNM) stages (all P < 0.05); and the expression of CD82 was negatively related to grades of tumor, lymph node metastasis, and TNM stages (all P < 0.05). The overall mean survival time of the patients with CD133, CD44, and the score of MVD (≥21) positive expression was lower than that of patients with negative expression. The overall mean survival time of patients of CD82-positive expression was longer than that of patients of the negative expression group. The positive expression of CD133 and CD82, and TNM stages were independent prognostic factors of IDC (P < 0.05).

CONCLUSIONS

CSCs, angiogenesis, and aberrant expression of CD82 may be involved in the initiation, development, metastasis, and recurrence. It is suggested that CSCs, angiogenesis, and CD82 be possible as a therapeutic marker for anti-tumor therapy.

Identification of a novel gene fusion (BMX-ARHGAP) in gastric cardia adenocarcinoma

Background

Gastric cardia adenocarcinoma (GCA) is one of the major causes of cancer related mortality worldwide. We aim to provide new understanding in the pathogenesis of GCA through investigations on gene expression alterations.

Methods

We preformed RNA-Seq for one pair of GCA and matched non-tumor tissues. Differentially expressed genes (DEGs) and fusion genes were acquired. PCR and gel analysis in additional 14 pairs of samples were performed to validate the chimeric transcripts.

Results

1590 up-regulated and 709 down-regulated genes were detected. Functional analysis revealed that these DEGs were significantly overrepresented in gene ontology items of cell cycle, tumor invasion and proliferation. Moreover, we firstly discovered 3 fusion genes in GCA, including BMX-ARHGAP, LRP5- LITAF and CBX3-C15orf57. The chimeric transcript BMX-ARHGAP was validated and recurrently occurred in 4/15 independent tumor tissues.

Conclusions

Our results may provide new understanding of GCA and biomarkers for further therapeutic studies.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_218

Tissue-specific splice variants of HARE/Stabilin-2 are expressed in bone marrow, lymph node, and spleen

The hyaluronan receptor for endocytosis (HARE), or Stabilin-2, is the mammalian endocytic clearance receptor for HA, heparin, advanced glycation end-products, acetylated and oxidized low-density lipoproteins and collagen N-terminal propeptides. This large 2551 amino acid receptor is encoded by a gene that covers over 180 kbp on human chromosome 12 and is predicted to be composed of 69 exons. Due to the expression profile of this gene and the number of exons it contains, we hypothesized that splice variants of stab2 are encoded in these tissues. In addition, a correlation between alternative splice variants and cancer progression has been shown in other HA receptors such as RHAMM and CD42. In this study, two methods were utilized in identifying and/or isolating the HARE splice variants. The first method used primer sets to amplify the 190-HARE encoding region that could contain splice junctions; therefore, they were purified from agarose gels and sequenced. Five splice variants were detected in that manner. In the second approach, the entire open reading frame of HARE was amplified. This allowed four splice variants with extensive exon splicing to be isolated. After the splice variants were sequenced, three were cloned into a mammalian expression vector. Next, stable cell lines expressing the variants were created in order to determine stable protein expression. In this study, the splice variants were found to be tissue specific in most cases. This suggests that tissue specific regulatory splicing mechanisms may lead to differences in functionality between the splice variants.

Regulation of alternative splicing of CD44 in cancer

CD44 is a hyaluronan binding cell surface signal transducing receptor that influences motility, cell survival and proliferation as well as the formation of tumor microenvironment. CD44 contains two variable regions encoded by variable exons. Alternative splicing, which is often deregulated in cancer, can produce various isoforms of CD44 with properties that may have different tissue specific effects and therefore even diverse effects on cancer progression. This review summarizes and puts together all major regulators of alternative splicing of CD44 in cancer that have been documented so far and that have an experimentally proved effect on CD44 isoform switching. It is important to better understand the mechanisms of alternative splicing of CD44, where all the variability of CD44 originates, to be able to explain the isoform switching and occurrence of variant isoforms of CD44 (CD44v) in cancer.

CD44v3 and VEGF-C expression and its relationship with lymph node metastasis in squamous cell carcinomas of the uterine cervix

BACKGROUND

To investigate the expression of CD44v3 and vascular endothelial growth factor-C (VEGF-C) and their relationship with lymph node metastasis in squamous cell carcinomas (SCC) of the uterine cervix.

MATERIALS AND METHODS

Expression of CD44v3 and VEGF-C was analyzed in 109 cases of cervical SCC by immunohistochemistry (IHC). The relationship was analyzed between expression and the patient age, histological differentiation, formation of tumor emboli in lymphoid vessels, lymph node metastasis, FIGO staging, and TNM classification.

RESULTS

Expression rates for both CD44v3 and VEGF-C were 43.1% in cervical SCC. The cells with positive immunohistochemical staining of CD44v3 were distributed mainly around the keratin pearls in well differentiated carcinomas, but distributed diffusely in the moderately and poorly differentiated lesions. VEGF-C was found stained positively in most of the tumor cells. There were differences in expression between normal epithelium and atypical hyperplasia as well as carcinoma. Both CD44v3 and VEGF-C were found to be associated positively with lymph node metastasis and TNM classification (both p=0.000). Neither CD44v3 nor VEGF-C was found to be associated with patient age, histological differentiation, formation of tumor emboli in lymphoid vessels and FIGO staging. CD44v3 was found to be associated with VEGF-C positively (p=0.000).

CONCLUSIONS

Abnormal expression of CD44v3 and VEGF-C is associated closely with the lymph node metastasis in cervical SCC, and these agents may cooperate in carcinogenesis and development of metastatic lesions.

Characterization of CD44 variant expression in head and neck squamous cell carcinomas

CD44 is a complex family of molecules, associated with aggressive malignancies and cancer stem cells. However, the role of CD44 variants in tumor progression and treatment resistance is not clear. In this study, the expression of CD44 and its variants was assessed in head and neck squamous cell carcinomas (HNSCC). Furthermore, subpopulations of cells expressing high amounts of CD44 variants were identified and characterized, for e.g., cell cycle phase and radioresistance. Results revealed high and homogenous CD44 and CD44v7 expression in four cell lines and CD44v4 and CD44v6 in three cell lines. CD44v3 was highly expressed in two cell lines, whereas CD44v5, CD44v7/8, CD44v10, CD133, and CD24 demonstrated no or moderate expression. Moreover, a subpopulation of very high CD44v4 expression was identified, which is independent of cell phase, demonstrating increased proliferation and radioresistance. In cell starvation experiments designed to enrich for cancer stem cells, a large population with dramatically increased expression of CD44, CD44v3, CD44v6, and CD44v7 was formed. Expression was independent of cell phase, and cells demonstrated increased radioresistance and migration rate. Our results demonstrate that the heterogeneity of tumor cells has important clinical implications for the treatment of HNSCC and that some of the CD44 variants may be associated with increased radioresistance. Highly expressed CD44 variants could make interesting candidates for selective cancer targeting.

Activation of c-Met and upregulation of CD44 expression are associated with the metastatic phenotype in the colorectal cancer liver metastasis model

BACKGROUND

Liver metastasis is the most common cause of death in patients with colorectal cancer. Despite extensive research into the biology of cancer progression, the molecular mechanisms that drive colorectal cancer metastasis are not well characterized.

METHODS

HT29 LM1, HT29 LM2, HT29 LM3 cell lines were derived from the human colorectal cancer cell line HT29 following multiple rounds of in vivo selection in immunodeficient mice.

RESULTS

CD44 expression, a transmembrane glycoprotein involved in cell-cell and cell-matrix adhesions, and cancer cells adhesion to endothelial cells was increased in all in vivo selected cell lines, with maximum CD44 expression and cancer cells adhesion to endothelial cells in the highly metastatic HT29 LM3 cell line. Activation of c-Met upon hepatocyte growth factor (HGF) stimulation in the in vivo selected cell lines is CD44 independent. In vitro separation of CD44 high and low expression cells from HT29 LM3 cell line with FACS sorting confirmed that c-Met activation is CD44 independent upon hepatocyte growth factor stimulation. Furthermore, in vivo evaluation of CD44 low and high expressing HT29 LM3 cells demonstrated no difference in liver metastasis penetrance.

CONCLUSIONS

Taken together, our findings indicate that the aggressive metastatic phenotype of in vivo selected cell lines is associated with overexpression of CD44 and activation of c-MET. We demonstrate that c-Met activation is CD44 independent upon hepatocyte growth factor stimulation and confirm that CD44 expression in HT29 LM3 cell line is not responsible for the increase in metastatic penetrance in HT29 LM3 cell line.

Evaluation of cancer stem cell markers CD133, CD44, CD24: association with AKT isoforms and radiation resistance in colon cancer cells

The cell surface proteins CD133, CD24 and CD44 are putative markers for cancer stem cell populations in colon cancer, associated with aggressive cancer types and poor prognosis. It is important to understand how these markers may predict treatment outcomes, determined by factors such as radioresistance. The scope of this study was to assess the connection between EGFR, CD133, CD24, and CD44 (including isoforms) expression levels and radiation sensitivity, and furthermore analyze the influence of AKT isoforms on the expression patterns of these markers, to better understand the underlying molecular mechanisms in the cell. Three colon cancer cell-lines were used, HT-29, DLD-1, and HCT116, together with DLD-1 isogenic AKT knock-out cell-lines. All three cell-lines (HT-29, HCT116 and DLD-1) expressed varying amounts of CD133, CD24 and CD44 and the top ten percent of CD133 and CD44 expressing cells (CD133high/CD44high) were more resistant to gamma radiation than the ten percent with lowest expression (CD133low/CD44low). The AKT expression was lower in the fraction of cells with low CD133/CD44. Depletion of AKT1 or AKT2 using knock out cells showed for the first time that CD133 expression was associated with AKT1 but not AKT2, whereas the CD44 expression was influenced by the presence of either AKT1 or AKT2. There were several genes in the cell adhesion pathway which had significantly higher expression in the AKT2 KO cell-line compared to the AKT1 KO cell-line; however important genes in the epithelial to mesenchymal transition pathway (CDH1, VIM, TWIST1, SNAI1, SNAI2, ZEB1, ZEB2, FN1, FOXC2 and CDH2) did not differ. Our results demonstrate that CD133high/CD44high expressing colon cancer cells are associated with AKT and increased radiation resistance, and that different AKT isoforms have varying effects on the expression of cancer stem cell markers, which is an important consideration when targeting AKT in a clinical setting.

Demonstration of a melanoma-specific CD44 alternative splicing pattern that remains qualitatively stable, but shows quantitative changes during tumour progression

The role of CD44 in the progression of human melanoma has mostly been characterised by qualitative changes in expression of its individual variable exons. These exons however, may be expressed to form a number of molecules, the alternative splice variants of CD44, which may be structurally and functionally different. Using real-time PCR measurements with variable exon specific primers we have determined that all are expressed in human melanoma. To permit comparison between different tumours we identified a stable CD44 variable exon (CD44v) expression pattern, or CD44 ‘fingerprint’. This was found to remain unchanged in melanoma cell lines cultured in different matrix environments. To evaluate evolution of this fingerprint during tumour progression we established a scid mouse model, in which the pure expression pattern of metastatic primary tumours, circulating cells and metastases, non-metastatic primary tumours and lung colonies could be studied. Our analyses demonstrated, that although the melanoma CD44 fingerprint is qualitatively stable, quantitative changes are observed suggesting a possible role in tumour progression.