Skin Squamous Cell Carcinoma Cells Research Articles

The mitochondrial RNA polymerase POLRMT promotes skin squamous cell carcinoma cell growth

RNA polymerase mitochondrial (POLRMT) expression and the potential biological functions in skin squamous cell carcinoma (SCC) were explored. We showed that POLRMT is significantly elevated in skin SCC. Genetic depletion of POLRMT, using shRNA-induced knockdown or CRISPR/Cas9-mediated knockout (KO), resulted in profound anti-skin SCC cell activity. In patient-derived primary skin SCC cells or immortalized lines (A431 and SCC-9), POLRMT shRNA or KO potently suppressed mitochondrial DNA (mtDNA) transcription and suppressed cell viability, proliferation and migration. POLRMT shRNA or KO impaired mitochondrial functions in different skin SCC cells, leading to production of ROS (reactive oxygen species), depolarization of mitochondria and depletion of ATP. Moreover, mitochondrial apoptosis cascade was induced in POLRMT-depleted skin SCC cells. IMT1, a POLRMT inhibitor, largely inhibited proliferation and migration, while inducing depolarization of mitochondria and apoptosis in primary skin SCC cells. Contrarily, ectopic overexpression of POLRMT increased mtDNA transcription and augmented skin SCC cell growth. Importantly, POLRMT shRNA adeno-associated virus injection robustly hindered growth of the subcutaneous A431 xenografts in mice. In the POLRMT shRNA virus-treated A431 xenograft tissues, POLRMT depletion, mtDNA transcription inhibition, cell apoptosis, lipid peroxidation and ATP depletion were detected. Together, overexpressed POLRMT increases mtDNA transcription and promotes skin SCC growth.

Smart Fe3O4@ZnO Core-Shell Nanophotosensitizers Potential for Combined Chemo and Photodynamic Skin Cancer Therapy Controlled by UVA Radiation.

PurposePhotodynamic therapy (PDT) is a non-invasive therapeutic modality that is used for several types of cancer and involves three essential elements (light, photosensitizer (PS), and oxygen). However, clinical PS is limited by the low yield of reactive oxygen species (ROS) and a long retention time. Therefore, developing a low-cost PS that can significantly increase ROS yield in a short time is of utmost importance.MethodsIn this study, brusatol (Bru) was loaded on the surface of ultraviolet A (UVA)-responsive zinc oxide (ZnO)-coated magnetic nanoparticles (Fe3O4@ZnO-Bru). The PS was well characterized by transmission electron microscopy (TEM), Fourier Transform infrared spectroscopy (FTIR), a superconducting quantum interference device, and dynamic light scattering (DLS). 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and Hoechst staining were used to determine the inhibitory effect of Fe3O4@ZnO-Bru on squamous cell carcinoma cells (SCC) with or without UVA radiation. Intracellular ROS levels and expression of the Nrf2 signaling pathway were also determined.ResultsFTIR showed that Bru was successfully loaded on Fe3O4@ZnO. Fe3O4@ZnO-Bru was superparamagnetic, and the zeta potential was 8.86 ± 0.77 mV. The Bru release behavior was controlled by UVA. Fe3O4@ZnO-Bru with UVA irradiation induced an increase of 48% ROS productivity compared to Fe3O4@ZnO-Bru without UVA irradiation, resulting in a strong inhibitory effect on SCC. Furthermore, Fe3O4@ZnO-Bru nanocomposites (Fe3O4@ZnO-Bru NCs) had nearly no toxic effect on healthy cells without UVA radiation. The released Bru could significantly inhibit the Nrf2 signaling pathway to reduce the activity of scavenging excess ROS in SCC.ConclusionIn this study, Fe3O4@ZnO-Bru was successfully synthesized. PDT was combined with photochemotherapy, which exhibited a higher inhibitory effect on SCC. It can be inferred that Fe3O4@ZnO-Bru holds great potential for skin SCC therapy.

Depletion of RIPK4 parallels higher malignancy potential in cutaneous squamous cell carcinoma.

BackgroundThe RIPK4 (receptor-interacting protein kinase 4), a member of the RIPK family, acts as an important regulator of epidermal differentiation, cutaneous inflammation, and cutaneous wound repair. However, Until now, the role of RIPK4 in tumorigenesis remains elusive. There have been no studies exploring the effects of RIPK4 on the signaling pathway in cutaneous squamous cell carcinoma (SCC). It remains unknown whether RIPK4 expression, which can affect the degree of epidermal differentiation can also influence the radiosensitivity of skin SCC. It is urgent to fully elucidate the biological mechanism by which RIPK4 promotes carcinogenesis in skin SCC and determine whether RIPK4 expression levels predicts the sensitivity to radiotherapy in skin SCC. MethodsHuman skin SCC cell line, A431, was transfected with either small interfering RNAs (siRNAs) targeting RIPK4 (siR-RIPK4) or negative control siRNA (siR-NC). Western blotting was used to detect the expression of RIPK4 and Raf/MEK/ERK pathway-related proteins. The cells were irradiated using an X-ray irradiator at 6 MV with different radiation doses (0, 2, 6, and 10 Gy). Cell proliferation analysis, colony formation assay, transwell cell migration and invasion assay, cell cycle and apoptosis analysis were conducted to investigate the effect of RIPK4 silencing on skin SCC malignancy and radiosensitivity.ResultsRIPK4 protein expression was significantly decreased in the A431 cells transfected with siR-RIPK4, compared with the A431 cells transfected with siR-NC. RIPK4 silencing facilitated the proliferation, colony formation, migration, and invasion ability of A431 cell line, while cell cycle progression or cell apoptosis were not significantly influenced. In contrast with the previous literature, Raf/MEK/ERK pathway was not effected by RIPK4 knockdown in skin SCC. RIPK4 knockdown could not reverse the radiation resistance of A431 cells to irradiation in vitro.ConclusionsIn general, although depletion of RIPK4 cannot reverse the radiation resistance of A431 cells in vitro, it parallels higher malignancy potential in cutaneous SCC. To our knowledge, this is the first report of the effects of RIPK4 expression on the Raf/MEK/ERK signaling pathway and radiosensitivity in cutaneous SCC. The better understanding of the molecular mechanism of RIPK4 in cutaneous SCC may provide a promising biomarker for skin SCC prognosis and treatment.

Targeting COX-2 potently inhibits proliferation of cancer cells in vivo but not in vitro in cutaneous squamous cell carcinoma.

BackgroundCyclooxygenase 2 (COX-2) is an inducible enzyme which promotes tumorigenesis in many types of cancers. Genetic knockout of COX-2 significantly suppresses the tumorigenesis of skin squamous cell carcinoma (SCC). However, COX-2 inhibitor treatment only showed mild to moderate inhibition on SCC in previous reports. The aim of this study is to solve this contradiction and to re-evaluate the therapeutic potential of targeting COX-2 in SCC.MethodsCOX-2 was knocked down by shRNA in two different SCC cell lines, A431 and SCC-13. The cells proliferation and migration capacity were evaluated by cell growth curves and monolayer scratch assay, respectively. Cancer cells with COX-2 knockdown were also xenografted into Balb/c nude mice and tumor growth curves were recorded over time. In addition, we changed the drug administration route and intraperitoneally injected COX-2 inhibitor celecoxib into mice to evaluate its anti-cancer activity.ResultsKnockdown of COX-2 exhibited mild or even no effect on cell proliferation and migration in two different SCC cell lines in vitro. However, when cancer cells were xenografted into nude mice, knockdown of COX-2 significantly suppressed proliferation of cancer cells in tumors. At last, intraperitoneal injection instead of oral administration of COX-2 inhibitor celecoxib potently suppressed tumor growth.ConclusionsOur results indicate that COX-2 might impact on the interaction between cancer cells and surrounding microenvironments rather than on cancer cells directly, and demonstrate that targeting COX-2 is a very promising therapeutic approach for SCC treatment.

SphK1-targeted miR-6784 inhibits functions of skin squamous cell carcinoma cells.

Sphingosine kinase 1 (SphK1) is overexpressed in skin squamous cell carcinoma (SCC). It has emerged as a novel therapeutic oncotarget. The current study identified a novel SphK1-targeting microRNA, microRNA-6784 (miR-6784). Here, we show that miR-6784 is located at the cytoplasm of A431 skin SCC cells. It directly binds to SphK1 mRNA. Ectopic overexpression of miR-6784 inhibited SphK1 3’-untranslated region (UTR) luciferase activity and downregulated its expression. Moreover, miR-6784 overexpression caused ceramide accumulation in skin SCC cells. Functional studies in established (A431 and SCC9) and primary skin SCC cells revealed that miR-6784 overexpression inhibited cell viability, proliferation, migration, and invasion. It also simultaneously provoked apoptosis activation. Conversely, miR-6784 silencing by antagomiR-6784 induced SphK1 elevation and augmented A431 cell proliferation, migration, and invasion. miR-6784 overexpression-induced anti-A431 cell activity was inhibited by the expression of an UTR-null SphK1 construct. CRISPR/Cas9-induced SphK1 knockout inhibited A431 cell growth. Importantly, miR-6784 was completely ineffective when treating SphK1-knockout A431 cells. Collectively, miR-6784 silences SphK1 and inhibits skin SCC cell progression.

I-BET726 suppresses human skin squamous cell carcinoma cell growth in vitro and in vivo

Bromodomain-containing protein 4 (BRD4) is a potential therapeutic target of skin squamous cell carcinoma (SCC). I-BET726 is a novel BRD4 inhibitor. Its potential effect in skin SCC cells was tested in the present study. We show that I-BET726 potently inhibited survival, proliferation, cell cycle progression, and migration in established (A431/SCC-9/SCC-12/SCC-13 lines) and primary human skin SCC cells. I-BET726 induced significant apoptosis activation in skin SCC cells. It was more efficient in inhibiting skin SCC cells than known BRD4 inhibitors (JQ1, CPI203, and AZD5153). I-BET726 not only downregulated BRD4-regulated proteins (c-Myc, Bcl-2, and cyclin D1), but also inhibited sphingosine kinase 1 (SphK1) and Akt signalings in SCC cells. Restoring Akt activation, by a constitutively active S473D mutant Akt1 (“caAkt1”), partially inhibited I-BET726-induced cytotoxicity in A431 cells. In vivo, I-BET726 oral administration potently inhibited A431 xenograft growth in severe combined immunodeficient mice. Downregulation of BRD4-regulated proteins and inhibition of the SphK1-Akt signaling were detected in I-BET726-treated A431 xenograft tumor tissues. Together, I-BET726 inhibits skin SCC cell growth in vitro and in vivo.

Context-dependent effect of sPLA2-IIA induced proliferation on murine hair follicle stem cells and human epithelial cancer.

BackgroundTissue stem cells (SCs) and cancer cells proliferation is regulated by many common signalling mechanisms. These mechanisms temporally balance proliferation and differentiation events during normal tissue homeostasis and repair. However, the effect of these aberrant signalling mechanisms on the ultimate fate of SCs and cancer cells remains obscure.MethodsTo evaluate the functional effects of Secretory Phospholipase A2-IIA (sPLA2-IIA) induced abnormal signalling on normal SCs and cancer cells, we have used K14-sPLA2-IIA transgenic mice hair follicle stem cells (HFSCs), DMBA/TPA induced mouse skin tumour tissues, human oral squamous cell carcinoma (OSCC) and skin squamous cell carcinoma (SCC) derived cell lines.FindingsOur study demonstrates that sPLA2-IIA induces rapid proliferation of HFSCs, thereby altering the proliferation dynamics leading to a complete loss of the slow cycling H2BGFP positive HFSCs. Interestingly, in vivo reversion study by JNK inhibition exhibited a significant delay in post depilation hair growth, confirming that sPLA2-IIA promotes HFSCs proliferation through JNK/c-Jun signalling. In a different cellular context, we showed increased expression of sPLA2-IIA in human OSCC and mouse skin cancer tissues. Importantly, a xenograft of sPLA2-IIA knockdown cells of OSCC and SCC cell lines showed a concomitant reduction of tumour volume in NOD-SCID mice and decreased JNK/c-Jun signalling.InterpretationThis study unravels how an increased proliferation induced by a common proliferation inducer (sPLA2-IIA) alters the fate of normal SCs and cancer cells distinctively through common JNK/c-Jun signalling. Thus, sPLA2-IIA can be a potential target for various diseases including cancer.FundThis work was partly supported by the Indian Council of Medical Research (ICMR-3097) and ACTREC (42) grants.

Tamoxifen inhibits the proliferation of non‑melanoma skin cancer cells by increasing intracellular calcium concentration.

Tamoxifen is an estrogen receptor (ER) antagonist used as first-line chemotherapy in breast cancer. Recent studies suggest that tamoxifen may be effective not only for ER‑positive but also for ER‑negative cancer cases. The aim of the present study was to investigate the antiproliferative effect of tamoxifen against human non‑melanoma skin cancer cells. Tamoxifen inhibited the proliferation of the skin squamous cell carcinoma (SCC) cell lines A431, DJM‑1 and HSC‑1. A431 cells did not express ER‑α or -β, suggesting that tamoxifen may exert antiproliferative effects on skin SCC cells via a non‑ER‑mediated pathway. Tamoxifen increased the intracellular calcium concentration of skin SCC cells, and this increase in intracellular calcium concentration by calcium ionophore A23187 suppressed the proliferation of skin SCC cells. These data indicate that tamoxifen inhibited the proliferation of human skin SCC cells via increasing intracellular calcium concentration. Voltage-gated calcium channels and non‑selective cation channels are involved in the increase in intracellular calcium concentration induced by tamoxifen. The broad-spectrum protein kinase C (PKC) inhibitor phloretin significantly attenuated the antiproliferative effect of tamoxifen on skin SCC cells. From these data, it may be concluded that tamoxifen inhibits the proliferation of skin SCC cells by induction of extracellular calcium influx via calcium channels in the plasma membrane and by subsequent activation of PKC.

IGF2BP1 over-expression in skin squamous cell carcinoma cells is essential for cell growth

The present study examined expression and potential functions of insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) in human skin squamous cell carcinoma (SCC). We show that IGF2BP1 mRNA and protein expression levels were upregulated in established (A431 line) and primary human skin SCC cells. Its expression was also increased in human skin SCC tissues, as compared to the normal skin tissues. In skin SCC cells, IGF2BP1 silencing or CRISPR/Cas9 knockout decreased levels of IGF2BP1-stablized mRNAs, including IGF2, CD44, Gli1 and Myc. Furthermore, skin SCC cell survival and proliferation were inhibited by IGF2BP1 silencing/knockout. Conversely, forced over-expression of IGF2BP1 further promoted A431 cell survival and proliferation. Furthermore, siRNA-mediated knockdown of IGF2BP1-bound long non-coding RNA THOR (“Lnc-THOR”) similarly depleted IGF2BP1-dependent mRNAs, causing inhibition on A431 cell survival and proliferation. In vivo, IGF2BP1 silencing or knockout inhibited A431 tumor xenograft growth in mice. Together, we conclude that IGF2BP1 over-expression in skin SCC cells is essential for cell growth.

Inhibitory effect of microRNA-154 targeting WHSC1 on cell proliferation of human skin squamous cell carcinoma through mediating the P53 signaling pathway.

Skin squamous cell carcinoma (SCC) is a common, morbid, and frequently lethal malignancy and ranks as the sixth most deadly cancer worldwide. Hence, this study aims to explore the effect of microRNA-154 (miR-154) targeting WHSC1 on proliferation and apoptosis of SCC cells via the P53 signaling pathway. The targeting relationship between WHSC1 and miR-154 was validated using dual-luciferase reporter assay. Normal human epidermal keratinocytes (NHEK) were included, and SCC A431 and SCC-15 cell lines were cultured and transfected with miR-154 mimic, miR-154 inhibitor or siRNA-WHSC1. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were used for the miR-154 expression and levels of WHSC1, P53 signaling pathway- and apoptosis-related genes. MTT assay and flow cytometry were applied to determine the cell viability and apoptosis. WHSC1 is a target gene of miR-154. MiR-154 negatively regulated WHSC1 expression and inhibited the activation of P53 signaling pathway. In response to miR-154 mimic or siRNA-WHSC1, SCC A431 and SCC-15 cell lines exhibited increased expression of P73, P16 and Bax, decreased expression of WHSC1, P53, c-myc and Bcl-2, as well as attenuated cell viability and enhanced cell apoptosis. The treatment of miR-154 inhibitor reversed the tendency. These results demonstrate that up-regulation of miR-154 inhibits proliferation and induces apoptosis of human skin SCC cells by down-regulating WHSC1 and blocking the P53 signaling pathway.

Targeting sphingosine kinase 2 by ABC294640 inhibits human skin squamous cell carcinoma cell growth

The activity of ABC294640, a small-molecular sphingosine kinase 2 (SphK2) inhibitor, in human skin squamous cell carcinoma (SCC) cells was tested in this study. SphK2 mRNA and protein are expressed in established (A431 cheilocarcinoma cell line) and primary human skin SCC cells. ABC294640 dose-dependently inhibited survival, cell cycle progression and proliferation of skin SCC cells. Furthermore, ABC294640 induced caspase-3/-9 and apoptosis activation in skin SCC cells. The SphK2 inhibitor was however non-cytotoxic to SphK2-null skin melanocytes, keratinocytes and fibroblasts. ABC294640 induced ceramide accumulation, sphingosine-1-phosphate (S1P) reduction, Akt-S6K1 inhibition and JNK activation in skin SCC cells. Conversely, its cytotoxicity against SCC cells was largely attenuated by co-treatment of S1P, the Akt activator SC79, and the JNK inhibitor SP600125. In vivo, ABC294640 oral administration inhibited A431 xenograft tumor growth in nude mice. Akt-S6K1 inhibition and JNK activation were observed in ABC294640-treated tumors. Collectively, ABC294640 efficiently inhibits human skin SCC cell growth in vitro and in vivo.

Bromodomain protein BRD4 promotes cell proliferation in skin squamous cell carcinoma

The present study examined the expression and biological functions of bromodomain-containing protein 4 (BRD4) in skin squamous cell carcinoma (SCC) cells. Our results show that BRD4 mRNA and protein expression was upregulated in human skin SCC cells, as compared to its level in the normal skin keratinocytes and fibroblasts. Treatment with BRD4 inhibitors, JQ1 and CPI203, resulted in proliferation inhibition, apoptosis and cell cycle arrest in both established (A431 cell line) and primary skin SCC cells. Furthermore, BRD4 knockdown (by targeted shRNAs) or knockout (by CRISPR/Cas9) largely inhibited A431 cell proliferation. Reversely, forced-overexpression of BRD4 in A431 cells facilitated cell proliferation. We show that BRD4 is required for the expression of several oncogenes, including cyclin D1, Bcl-2 and MYC. BRD4 inhibition, knockdown or knockout significantly decreased above oncogene expression in SCC cells. In vivo, CRISPR/Cas9-mediated BRD4 knockout significantly suppressed A431 xenograft tumor growth in severe combined immunodeficient (SCID) mice. Together, our results suggest that BRD4 could be a novel and pivotal oncogenic protein of skin SCC.

Nuclear FAK and Runx1 Cooperate to Regulate IGFBP3, Cell-Cycle Progression, and Tumor Growth.

Nuclear focal adhesion kinase (FAK) is a potentially important regulator of gene expression in cancer, impacting both cellular function and the composition of the surrounding tumor microenvironment. Here, we report in a murine model of skin squamous cell carcinoma (SCC) that nuclear FAK regulates Runx1-dependent transcription of insulin-like growth factor binding protein 3 (IGFBP3), and that this regulates SCC cell-cycle progression and tumor growth in vivo Furthermore, we identified a novel molecular complex between FAK and Runx1 in the nucleus of SCC cells and showed that FAK interacted with a number of Runx1-regulatory proteins, including Sin3a and other epigenetic modifiers known to alter Runx1 transcriptional function through posttranslational modification. These findings provide important new insights into the role of FAK as a scaffolding protein in molecular complexes that regulate gene transcription. Cancer Res; 77(19); 5301-12. ©2017 AACR.

Targeting PI3K-AKT-mTOR by LY3023414 inhibits human skin squamous cell carcinoma cell growth in vitro and in vivo

Abnormal activation of PI3K-AKT-mTOR signaling is detected in human skin squamous cell carcinoma (SCC). LY3023414 is a novel, potent, and orally bio-available PI3K-AKT-mTOR inhibitor. Its activity against human skin SCC cells was tested. We demonstrated that LY3023414 was cytotoxic when added to established (A431 line) and primary (patient-derived) human skin SCC cells. LY3023414 induced G0/1-S arrest and inhibited proliferation of skin SCC cells. Moreover, LY3023414 induced activation of caspase-3/-9 and apoptosis in skin SCC cells. Intriguingly, LY3023414 was yet non-cytotoxic nor pro-apoptotic to normal human skin cells (melanocytes, keratinocytes and fibroblasts). At the molecular level, LY3023414 blocked PI3K-AKT-mTOR activation in skin SCC cells, as it dephosphorylated PI3K-AKT-mTOR substrates: P85, AKT and S6K1. In vivo studies showed that oral administration of LY3023414 at well-tolerated doses inhibited A431 xenograft tumor growth in severe combined immunodeficiency (SCID) mice. AKT-mTOR activation in LY3023414-treated tumors was also largely inhibited. Together, these results suggest that targeting PI3K-AKT-mTOR by LY3023414 inhibits human skin SCC cell growth in vitro and in vivo, establishing the rationale for further clinical testing.

Imatinib Induces Growth Inhibition via Down Regulation of SKP2 in A431Human Skin Squamous Cell Carcinoma Cells

S-phase-kinase-associated protein 2 (SKP2) plays a crucial role in the tumorigenesis of various human cancers. Imatinib, an inhibitor of BCR-ABL tyrosine kinase, c-kit, and platelet derived growth factor receptors, has been approved for the treatment and investigation of chronic myeloid leukemia, gastrointestinal stromal tumors, and various other solid tumors. However, its efficacy in the treatment of skin squamous cell carcinoma (SSCC) has not yet been investigated. The aim of this study was to investigate whether imatinib has an antitumor effect in human SSCC cells and evaluate its functional relationship with SKP2. To research the effect of imatinib on the growth of A431 SSCC cells, we conducted a proliferation assay and flow cytometry. A western blot assay was performed to verify the function of imatinib in A431 cells and evaluate the underlying molecular mechanism. Imatinib significantly inhibited cell growth and induced cell cycle arrest at the G0/G1 phase. Furthermore, the depletion of SKP2 triggered cell cycle arrest and inhibited colony formation. Mechanistically, imatinib markedly downregulated SKP2 protein expression and subsequently upregulated P21 expression via increased protein stability. In conclusion, imatinib demonstrated an antitumor activity against SSCC cells via the SKP2-P21 signaling axis and targeting SKP2 using imatinib could be a novel therapeutic approach for SSCC that warrants further study.

Insulin-like growth factor 2 mRNA-binding protein-3 as a marker for distinguishing between cutaneous squamous cell carcinoma and keratoacanthoma.

In the histopathological diagnosis of cutaneous tumors, the differential diagnosis of squamous cell carcinoma (SCC) with crateriform architecture and keratoacanthoma (KA) is often difficult so an accurate understanding of the biological features and the identification of reliable markers of SCC and KA are crucial issues. Insulin-like growth factor 2 mRNA-binding protein-3 (IGF2BP3, also known as IMP3) is thought of as a bona fide oncofetal protein, which is overexpressed and is involved in cell proliferation, migration, and invasion in several kinds of tumors. However, the role of IMP3 in cutaneous SCC and KA has not been well studied. Therefore, we focused on studying the biological functions of IMP3 in SCC and KA. In human skin SCC cell lines, HSC-1 and HSC-5, and the human keratinocyte cell line, HaCaT, IMP3 mRNA levels were significantly higher than that of normal human skin. The knockdown of IMP3 expression reduced the proliferation of HSC-1, and significantly reduced invasion by HSC-1 and HSC-5. In contrast, the knockdown of IMP3 did not significantly affect invasion by HaCaT cells. In immunohistochemical studies of SCC and KA tissues, the Ki-67 labeling index (LI) of the suprabasal cell layer was significantly higher in SCC, compared with KA tissues and the tumor-free margin (TFM) adjacent to SCC and KA. Most SCC tissues stained strongly positive for IMP3, but KA tissues and TFM were mostly negative for IMP3. The Ki-67 LI of the IMP3-positive group was significantly higher than that of the IMP3-negative group in the suprabasal cell layer of SCC. These results suggest that IMP3 plays an important role in proliferation and, more significantly, in the invasion of SCC, and may be a suitable marker for the histopathological diagnosis of SCC with a crateriform architecture and KA. Furthermore, IMP3 may potentially be a new therapeutic target for SCC.

TIPE2 regulates tumor-associated macrophages in skin squamous cell carcinoma.

Tumor-associated macrophages (TAMs) play an essential role in the immunology, growth, invasion, and metastases of skin squamous cell carcinoma (SCC). However, the molecular mechanisms underlying the activation and regulation of TAMs by SCC are not completely understood. Here, in a Transwell co-culture system, we found that SCC cells induced polarization of macrophages to a M2 phenotype, evident by expression of surface markers CD163, CD206, and CD301, as well as reduction of cellular iNOS levels and augmentation of cellular arginase levels. Moreover, tumor necrosis factor (TNF)-alpha-induced protein 8-like 2 (TIPE2) was induced in macrophages by co-culturing with SCC cells. Depletion of TIPE2 in macrophages abolished the effects of co-cultured SCC cells on phenotypic modification of macrophages. Furthermore, patients with SCC were divided into two groups based on TIPE2 levels in TAMs at the time of tumor resection. We found that patients with high-TIPE2 TAMs had an overall poor 5-year survival. Together, our data suggest a previously unappreciated role of TIPE2 in the crosstalk between skin SCC and TAMs and highlight TIPE2 as a promising novel target for skin SCC treatment.

Autophagy in human skin squamous cell carcinoma: Inhibition by 3-MA enhances the effect of 5-FU-induced chemotherapy sensitivity.

Autophagy is an intracellular multi-step catabolic degradation process that involves the degradation and recycling of cellular proteins and cytoplasmic damaged organelles to maintain cellular homeostasis and reduction of metabolic stress. Numerous studies have indicated the importance of autophagy in cancer, but the role of autophagy in human skin squamous cell carcinoma (SSCC) development and response to therapy it is still unclear. In the present study, we investigated the role of autophagy in SSCC and the relationship with chemotherapy sensitivity. The present study demonstrated that autophagy related gene the microtubule-associated protein 1 light chain 3 (LC3) expression was low in SSCC. The negative correlation with Bcl2 and survivin, and the chemotherapy drug 5-FU increased the level of autophagy and the autophagy inhibitor 3-MA inhibited this effect in SSCC cells, time- and dose-dependently. When SSCC cells were treated first with 3-MA and then with 5-FU, the inhibition of proliferation, migration, invasion and apoptosis of SSCC cells was enhanced. Our results suggested the possibility of autophagy as a potential target in SSCC therapy and 3-MA and 5-FU combination treatment may be an effective SSCC therapy via autophagy modulating.

Ginsenoside Rh2 Inhibits Cancer Stem-Like Cells in Skin Squamous Cell Carcinoma

Background/Aims: Treatments targeting cancer stem cells (CSCs) are most effective cancer therapy, whereas determination of CSCs is challenging. We have recently reported that Lgr5-positive cells are cancer stem cells (CSCs) in human skin squamous cell carcinoma (SCC). Ginsenoside Rh2 (GRh2) has been shown to significantly inhibit growth of some types of cancers, whereas its effects on the SCC have not been examined. Methods: Here, we transduced human SCC cells with lentivirus carrying GFP reporter under Lgr5 promoter. The transduced SCC cells were treated with different doses of GRh2, and then analyzed cell viability by CCK-8 assay and MTT assay. The effects of GRh2 on Lgr5-positive CSCs were determined by fow cytometry and by tumor sphere formation. Autophagy-associated protein and β-catenin were measured by Western blot. Expression of short hairpin small interfering RNA (shRNA) for Atg7 and β-catenin were used to inhibit autophagy and β-catenin signaling pathway, respectively, as loss-of-function experiments. Results: We found that GRh2 dose-dependently reduced SCC viability, possibly through reduced the number of Lgr5-positive CSCs. GRh2 increased autophagy and reduced β-catenin signaling in SCC cells. Inhibition of autophagy abolished the effects of GRh2 on β-catenin and cell viability, while increasing β-catenin abolished the effects of GRh2 on autophagy and cell viability. Conclusion: Taken together, our data suggest that GRh2 inhibited SCC growth, possibly through reduced the number of Lgr5-positive CSCs. This may be conducted through an interaction between autophagy and β-catenin signaling.

CXCR7 expression correlates with tumor depth in cutaneous squamous cell carcinoma skin lesions and promotes tumor cell survival through ERK activation.

The chemokine receptor CXCR7 has been demonstrated to be involved in the development of certain cancers, but its role in cutaneous squamous cell carcinoma (SCC) has not been previously investigated. We seek to determine whether CXCR7 is expressed in human cutaneous SCC skin lesions and SCC cell lines. In addition, we evaluate whether CXCR7 plays a role in SCC cell proliferation, survival and migration and which signalling pathways are involved. Using quantitative RT-PCR to analyse the mRNA expression of 19 different chemokine receptors, we found that CXCR7 was much more highly expressed compared to other chemokine receptors in cutaneous SCC cell lines (HSC-1 and HSC-5). On immunohistochemical staining, CXCR7 was found to be expressed in 70% (28 of 40) of human cutaneous SCC tissue specimens, and its expression correlated with tumor depth >4mm and cancer stage ≥II. CXCR7 but not CXCR4 protein was expressed on the surface of HSC-1 and HSC-5 cells by flow cytometry. Activation of the CXCR7 receptor by CXCL12 promoted survival of HSC-1 and HSC-5 cells through the ERK pathway, but had no significant effect on cell proliferation or migration. In summary, our findings indicate that CXCR7 is frequently expressed in cutaneous SCC skin lesions and its expression correlates with tumor depth and cancer stage. CXCR7 is the predominant chemokine receptor expressed in SCC cell lines, and activation of CXCR7 by CXCL12 promotes survival of SCC cells through the ERK pathway. These findings provide new insights into the significance of CXCR7 in the pathophysiology of SCC.