STK33 overexpression in hypopharyngeal squamous cell carcinoma: possible role in tumorigenesis

Serine/Threonine Kinase (STK) 33 promotes the proliferation and metastasis of human esophageal squamous cell carcinoma via inflammation-related pathway

The serine/threonine kinase (STK) 33 plays a key role in cancer cell proliferation and metastasis. Abnormal STK33 expression is closely related to malignancy of numerous cancers. This study suggests the important role of STK33 in the pathogenesis and metastatic progression of esophageal squamous cell carcinoma (ESCC). STK33 expression in human ESCC tissues was detected by immunohistochemical technique. Further, we analyzed the relationship between STK33 and clinical and pathological factors as well as the prognosis of patients. ECa109 cell line was cultured and transfected with STK33-RNAi lentiviral vector to perform Hochest33342 & PI and metastasis experiments. The TCGA database was used to analyze the STK33 expression level in ESCC. All statistical analyses were performed in SPSS 23.0 software. Differences with P < 0.05 were considered statistically significant. In human ESCC specimens, STK33 was overexpressed and associated with poor prognosis. Silencing STK33 expression suppressed ESCC proliferation, migration, invasion, and tumor growth. STK33 also mediated angiogenesis, TGFβ, and inflammatory response in ESCC. Mechanistic investigations revealed that STK33 regulates ESCC through multiple complex pathways. Dysregulated STK33 signaling promotes ESCC growth and progression. Thus, our findings identified STK33 as a candidate treatment target that improves ESCC therapy.

The role of flavonoids in the regulation of epithelial-mesenchymal transition in cancer: A review on targeting signaling pathways and metastasis

One of the hallmarks of cancer is metastasis, a process that entails the spread of cancer cells to distant regions in the body, culminating in tumor formation in secondary organs. Importantly, the proinflammatory environment surrounding cancer cells further contributes to cancer cell transformation and extracellular matrix destruction. During metastasis, front-rear polarity and emergence of migratory and invasive features are manifestations of epithelial-mesenchymal transition (EMT). A variety of transcription factors (TFs) are implicated in the execution of EMT, the most prominent belonging to the Snail Family Transcriptional Repressor (SNAI) and Zinc Finger E-Box Binding Homeobox (ZEB) families of TFs. These TFs are regulated by interaction with specific microRNAs (miRNAs), as miR34 and miR200. Among the several secondary metabolites produced in plants, flavonoids constitute a major group of bioactive molecules, with several described effects including antioxidant, antiinflammatory, antidiabetic, antiobesogenic, and anticancer effects. This review scrutinizes the modulatory role of flavonoids on the activity of SNAI/ZEB TFs and on their regulatory miRNAs, miR-34, and miR-200. The modulatory role of flavonoids can attenuate mesenchymal features and stimulate epithelial features, thereby inhibiting and reversing EMT. Moreover, this modulation is concomitant with the attenuation of signaling pathways involved in diverse processes as cell proliferation, cell growth, cell cycle progression, apoptosis inhibition, morphogenesis, cell fate, cell migration, cell polarity, and wound healing. The antimetastatic potential of these versatile compounds is emerging and represents an opportunity for the synthesis of more specific and potent agents.

NFYB potentiates STK33 activation to promote cisplatin resistance in diffuse large B-cell lymphoma

BACKGROUND

The aberrant expression of serine/threonine kinase 33 (STK33) has been implicated in cancers. However, its clinical significance and biological functions in diffuse large B cell lymphoma (DLBCL) remain largely unknown. In the present investigation, we delineated the expression of STK33 in DLBCL and its function in cisplatin resistance.

METHODS

First, genes associated with drug resistance as well as occurrence in DLBCL were analyzed by bioinformatics, followed by correlation analysis between STK33 expression and clinical baseline information of patients with DLBCL. Further, cisplatin-resistant DLBCL cell lines were constructed, and changes in cell sensitivity to cisplatin treatment were examined after interfering the expression of STK33 in parental cells as well as in drug-resistant cells, respectively. Subsequently, the downstream signaling pathways of STK33 were analyzed. Finally, the upstream regulatory mechanism of STK33 was predicted by bioinformatics as well as experimentally validated.

RESULTS

STK33 was overexpressed in the patients with DLBCL as well as in cisplatin-resistant DLBCL cells, and knockdown of STK33 significantly promoted sensitivity of resistant cells to cisplatin. Moreover, our further analysis revealed that STK33 promoted cisplatin resistance in DLBCL by activating the Hedgehog signaling pathway. We found in subsequent experiments that nuclear transcription factor Y subunit beta (NFYB) can bind to the STK33 promoter and thus promote STK33 expression.

CONCLUSIONS

The transcription factor NFYB expedites the transcription of SYK33 by binding to the STK33 promoter, thereby activating the Hedgehog signaling pathway in DLBCL cells, which in turn promotes the resistance of DLBCL cells to cisplatin.

Rare case of hepatocellular carcinoma metastasising to the pituitary and cavernous sinus causing panhypopituitarism and bilateral ophthalmoplegia

Pituitary metastases, especially from a primary hepatocellular carcinoma (HCC), are rare. Review of the literature revealed only few cases reporting pituitary metastases complicated by panhypopituitarism from HCC. Calvarial metastases from HCC are even more rare. Here, we present a unique case of primary HCC with metastases to both the calvarium and the pituitary causing panhypopituitarism and bilateral ophthalmoplegia, respectively. To our knowledge, this is the first reported case of two unique and rare complications from metastatic HCC.

Recent developments in targeting genes and pathways by RNAi-based approaches in colorectal cancer

A wide spectrum of genetic and epigenetic variations together with environmental factors has made colorectal cancer (CRC), which involves the colon and rectum, a challenging and heterogeneous cancer. CRC cannot be effectively overcomed by common conventional therapies including surgery, chemotherapy, targeted therapy, and hormone replacement which highlights the need for a rational design of novel anticancer therapy. Accumulating evidence indicates that RNA interference (RNAi) could be an important avenue to generate great therapeutic efficacy for CRC by targeting genes that are responsible for the viability, cell cycle, proliferation, apoptosis, differentiation, metastasis, and invasion of CRC cells. In this review, we underline the documented benefits of small interfering RNAs and short hairpin RNAs to target genes and signaling pathways related to CRC tumorigenesis. We address the synergistic effects of RNAi-mediated gene knockdown and inhibitors/chemotherapy agents to increase the sensitivity of CRC cells to common therapies. Finally, this review points new delivery systems/materials for improving the cellular uptake efficiency and reducing off-target effects of RNAi.

STK33 Promotes the Growth and Progression of Human Pancreatic Neuroendocrine Tumour via Activation of the PI3K/AKT/mTOR Pathway

BACKGROUND

Serine/threonine kinase 33 (STK33) has been reported to play an important role in cancer cell proliferation. We investigated the role of STK33 in pancreatic neuroendocrine tumour (PNET) and the underlying mechanisms.

METHODS

PNET specimens and adjacent non-tumorous pancreatic tissues from 84 patients who underwent curative surgery for PNET were stained by immunochemistry for STK33. The relationships among STK33 expression, clinicopathological parameters and clinical prognosis were statistically analysed. MTT, scratching, Transwell and apoptosis assays were employed to detect the effects of STK33 knockdown (siSTK33) or STK33 overexpression (pSTK33) on major oncogenic properties of cells of 2 PNET cell lines (BON and QGP-1), and real-time PCR and western blot were used to examine the expression of relevant genes.

RESULTS

Relative to its expression in normal pancreatic tissue, STK33 was overexpressed in PNET specimens. Furthermore, STK33 expression was significantly associated with World Health Organization classification (p < 0.001), American Joint Committee on Cancer stage (p < 0.001), lymph node metastasis (p < 0.001), tumour size (p = 0.022), sex (p = 0.003), perineural invasion (p < 0.001) and shorter disease-free survival of patients with PNET (p < 0.001). Enforced STK33 expression promoted PNET cell proliferation, migration and invasion and tumour growth and inhibited cell apoptosis, whereas STK33 depletion exerted the opposite effects. Mechanistic studies revealed that STK33 promoted growth and progression of PNET via activation of the phosphotidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway.

CONCLUSIONS

STK33 plays important roles in the tumour growth and progression of PNET via activation of the PI3K/AKT/mTOR pathway and has potential as a therapeutic target to improve PNET treatment.

STK33/ERK2 signal pathway contribute the tumorigenesis of colorectal cancer HCT15 cells

Serine/threonine kinase 33 (STK33) is a serine/threonine kinase and participates in many apoptotic process. Herein, we found that the extracellular signal-regulated kinase 2 (ERK2) was a substrate of STK33. STK33 phosphorylated ERK2 and increased the activity of ERK2 and promote the tumorigenesis of colorectal cancer HCT15 cells. Clinical simple showed that STK33 was highly expression in colorectal cells and tissues. Ex vivo and in vivo studies demonstrated that STK33 accelerate tumorigenic properties in NCM460 cells and athymic nude rats. In vitro kinase assay results indicated that STK33 can phosphorylate ERK2. Ex vivo studies further showed that STK33 can bind with ERK2 and take part in the regulation of ERKs signaling pathway. In short, our results showed that STK33 is a novel upstream kinase of ERK2. It may provide a better prospect for STK33 based prevention and treatment for colorectal cancer patients.

STK33 alleviates gentamicin-induced ototoxicity in cochlear hair cells and House Ear Institute-Organ of Corti 1 cells

Serine/threonine kinase 33 (STK33), a member of the calcium/calmodulin‐dependent kinase (CAMK), plays vital roles in a wide spectrum of cell processes. The present study was designed to investigate whether STK33 expressed in the mammalian cochlea and, if so, what effect STK33 exerted on aminoglycoside‐induced ototoxicity in House Ear Institute‐Organ of Corti 1 (HEI‐OC1) cells. Immunofluorescence staining and western blotting were performed to investigate STK33 expression in cochlear hair cells (HCs) and HEI‐OC1 cells with or without gentamicin treatment. CCK8, flow cytometry, immunofluorescence staining and western blotting were employed to detect the effects of STK33 knockdown, and/or U0126, and/or N‐acetyl‐L‐cysteine (NAC) on the sensitivity to gentamicin‐induced ototoxicity in HEI‐OC1 cells. We found that STK33 was expressed in both mice cochlear HCs and HEI‐OC1 cells, and the expression of STK33 was significantly decreased in cochlear HCs and HEI‐OC1 cells after gentamicin exposure. STK33 knockdown resulted in an increase in the cleaved caspase‐3 and Bax expressions as well as cell apoptosis after gentamicin damage in HEI‐OC1 cells. Mechanistic studies revealed that knockdown of STK33 led to activated mitochondrial apoptosis pathway as well as augmented reactive oxygen species (ROS) accumulation after gentamicin damage. Moreover, STK33 was involved in extracellular signal‐regulated kinase 1/2 pathway in primary culture of HCs and HEI‐OC1 cells in response to gentamicin insult. The findings from this work indicate that STK33 decreases the sensitivity to the apoptosis dependent on mitochondrial apoptotic pathway by regulating ROS generation after gentamicin treatment, which provides a new potential target for protection from the aminoglycoside‐induced ototoxicity.

Krüppel-like Factor 4 Suppresses Serine/Threonine Kinase 33 Activation and Metastasis of Gastric Cancer through Reversing Epithelial-Mesenchymal Transition

Background: Cancers with aberrant expression of Serine/threonine kinase 33 (STK33) has been reported to be particularly aggressive. However, its expression, clinical significance, and biological functions in gastric cancer remain largely unknown. In the present study, we determined the expression and function of STK33 in gastric cancer and delineated the clinical significance of the Krüppel-like factor 4 (KLF4)/STK33 signaling pathway.Methods: STK33 expression and its association with multiple clinicopathologic characteristics were analyzed immunohistochemically in human gastric cancer specimens. STK33 knockdown and overexpression were used to dissect the underlying mechanism of its functions in gastric cancer cells. Regulation and underlying mechanisms of STK33 expression by KLF4 in gastric cancer cells were studied using cell and molecular biological methods.Results: Drastically higher expression of STK33 was observed in gastric cancer and gastric intraepithelial neoplasia tissues compared with adjacent normal gastric tissues. Increased STK33 expression correlated directly with tumor size, lymph node, and distant metastasis; and patients with low STK33 expression gastric cancer were predicted to have a favorable prognosis. Enforced expression of STK33 promoted gastric cancer cell proliferation, migration, and invasion in vitro and in vivo, whereas reduced STK33 did the opposite. Moreover, STK33 promoted epithelial-mesenchymal transition (EMT) in vitro Mechanistically, KLF4 transcriptionally inhibited STK33 expression in gastric cancer cells. KLF4-mediated inhibition of gastric cancer cell invasion was reversed by upregulation of STK33 expression.Conclusions: STK33 has pro-tumor function and is a critical downstream mediator of KLF4 in gastric cancer. STK33 may serve as a potential prognostic marker and therapeutic target for gastric cancer. Clin Cancer Res; 24(10); 2440-51. ©2018 AACR.

STK33 Promotes Growth and Progression of Pancreatic Cancer as a Critical Downstream Mediator of HIF1α

The serine/threonine kinase STK33 has been implicated in cancer cell proliferation. Here, we provide evidence of a critical role for STK33 in the pathogenesis and metastatic progression of pancreatic ductal adenocarcinoma (PDAC). STK33 expression in PDAC was regulated by the hypoxia-inducible transcription factor HIF1α. In human PDAC specimens, STK33 was overexpressed and associated with poor prognosis. Enforced STK33 expression promoted PDAC proliferation, migration, invasion, and tumor growth, whereas STK33 depletion exerted opposing effects. Mechanistic investigations showed that HIF1α regulated STK33 via direct binding to a hypoxia response element in its promoter. In showing that dysregulated HIF1α/STK33 signaling promotes PDAC growth and progression, our results suggest STK33 as a candidate therapeutic target to improve PDAC treatment. Cancer Res; 77(24); 6851-62. ©2017 AACR.

Role of serine/threonine kinase 33 methylation in colorectal cancer and its clinical significance

Serine/threonine kinase 33 (STK33) is a novel protein that has been the focus of an increasing number of studies in recent years; however, the role of STK33 in tumorigenesis remains controversial. Previous studies have demonstrated that STK33 is overexpressed in several human cancers and exerts a pro-tumorigenic effect through the promotion of cell proliferation. However, the role of STK33 in colorectal cancer (CRC), which is one of the most aggressive human malignancies, remains unclear. The aim of the current study was to investigate the methylation status of STK33 in CRC and to determine its clinical significance. The results demonstrated that STK33 was hypermethylated in CRC cell lines and promoted the proliferation of CRC cells. In addition, the methylation status and expression of STK33 in 94 pairs of cancer and noncancerous tissues obtained from patients with CRC was investigated. STK33 methylation was significantly increased in cancer tissues when compared with adjacent noncancerous tissues (P<0.001). STK33 methylation was associated with lymph node metastasis (P<0.05), tumor invasion (P<0.05), distant metastases (P<0.01) and tumor stage (P<0.01). Reduced STK33 mRNA and protein expression in CRC was associated with STK33 hypermethylation (P<0.001). In addition, patients with hypermethylated STK33 exhibited shorter overall survival rates when compared with those with unmethylated STK33 (P<0.01). In conclusion, the results of the current study suggest that STK33 hypermethylation may be a promising novel biomarker for the diagnosis, prognosis and suitable treatment of CRC.

STK33 participates to HSP90-supported angiogenic program in hypoxic tumors by regulating HIF-1α/VEGF signaling pathway

Lately, the HSP90 client serine/threonine kinase STK33 emerged to be required by cancer cells for their viability and proliferation. However, its mechanistic contribution to carcinogenesis is not clearly understood. Here we report that elevated STK33 expression correlates with advanced stages of human pancreatic and colorectal carcinomas. Impaired proliferation and augmented apoptosis associated with genetic abrogation of STK33 were paralleled by decreased vascularization in tumor xenografts. In line with this, ectopic STK33 not only promoted tumor growth after pharmacologic inhibition of HSP90 using structurally divergent small molecules currently in clinical development, but also restored blood vessel formation in vivo. Mechanistic studies demonstrated that HSP90-stabilized STK33 interacts with and regulates hypoxia-driven accumulation and activation of HIF-1α as well as secretion of VEGF-A in hypoxic cancer cells. In addition, our study reveals a putative cooperation between STK33 and other HSP90 client protein kinases involved in molecular and cellular events through which cancer cells ensure their survival by securing the oxygen and nutrient supply. Altogether, our findings indicate that STK33 interferes with signals from hypoxia and HSP90 to promote tumor angiogenesis and tumor growth.

Correlation between STK33 and the pathology and prognosis of lung cancer

Correlation between the expression of STK33 and the pathology of lung cancer was investigated, to explore its effects on prognosis. Hundred and two lung cancer patients diagnosed by pathological examinations were randomly selected in Shanghai Jiao Tong University Affiliated Sixth People's Hospital from February, 2012 to February, 2017 to serve as observation group, and the tumor tissues were collected. At the same time, 19 patients with lung benign lesions were selected and lung tissues were also collected to serve as control group. RT-qPCR was used to detect the expression of STK33 mRNA in tissues. Expression levels of STK33 protein were detected and compared by SP immunohistochemistry staining and western blot analysis. Statistical analysis was performed to analyze the correlation between STK33 expression and the pathology and prognosis of lung cancer. Results of PCR showed that expression level of STK33 gene in control group was significantly lower than that in observation group (p<0.05). The expression level of STK33 mRNA in lung adenocarcinoma and squamous cell carcinoma was lower than that in lung small cell carcinoma and large cell carcinoma (p<0.05). Western blot analysis showed that the expression level of STK33 protein in lung small cell carcinoma and large cell carcinoma was significantly higher than that in lung adenocarcinoma and squamous cell carcinoma (p<0.05). Immunohistochemistry staining showed that the positive rate of STK33 in lung large cell carcinoma (100%) and small cell carcinoma (100%) was significantly higher than that in lung adenocarcinoma (88.1%) and squamous cell carcinoma (86.2%) (p<0.05). The 5-year survival rate analysis showed that the recurrence-free survival rate and overall survival rate of STK33 gene high expression level group were significantly lower than those of low expression level group (p<0.05). The differential expression level of STK33 is related to the pathology and prognosis of lung cancer, which is of great value in clinical diagnosis and prognosis evaluation.

FoxM1 overexpression promotes cell proliferation and migration and inhibits apoptosis in hypopharyngeal squamous cell carcinoma resulting in poor clinical prognosis

Forkhead box M1 (FoxM1), a member of the Fox family of transcriptional factors, is involved in the development of various human malignancies. However, the expression level of FoxM1 and its functional role in hypopharyngeal squamous cell carcinoma (HSCC) remained unclear to date. The aim of the present study was to investigate the FoxM1 expression in 63 HSCC and 20 adjacent normal tissues, as well as to evaluate its association with the clinicopathological parameters and its diagnostic value in HSCC. To further explore the biological function of FoxM1 in vitro, siRNAs were used to knockdown the expression of FoxM1 in the HSCC cell line Fadu. The results revealed that FoxM1 protein was highly expressed in HSCC tissues and that its high expression was closely associated with HSCC tumor differentiation (P=0.004), tumor size (P=0.002), clinical stage (P=0.001), lymph node metastasis (P=0.002), treatment (P=0.045) and expression of the proliferation marker Ki-67 (P<0.001). Additionally, the elevated expression of FoxM1 in HSCC patients consistently predicted a poor survival time. Knockdown of FoxM1 expression blocked Fadu cell proliferation and promoted apoptosis, and also led to the down-regulation of cyclin A1 expression. Furthermore, decreased expression of FoxM1 markedly impeded cell migration and reversed the epithelial-mesenchymal transition phenotype, as indicated by decreased expression of vimentin and increased expression of E-cadherin in Fadu cells. These results indicate that FoxM1 may act as an oncogene and serve as a therapeutic target against malignant progression in HSCC.

STK33 potentiates the malignancy of hypopharyngeal squamous carcinoma: Possible relation to calcium

BACKGROUND

The present study aims to further explore the role of STK33 in hypopharyngeal squamous cell carcinoma (HSCC), with special attention given to the possible relationship between STK33 alteration and calcium.

METHODS

An in vivo experiment and microarray analysis were performed to investigate the impact of STK33 knockdown (STK33-RNAi) on the biological behaviors and the gene profile alterations of a HSCC cell line (Fadu). Cell viability and morphological change of Fadu cells in response to Ionomycin were measured by MTT assay and acridine orange staining. The concentration of intracellular calcium ([Ca(2+)]i) was detected by laser scanning confocal microscope with fluo-3/AM. The mRNA and protein expressions of relevant genes were examined by real-time PCR and Western blot.

RESULTS

STK33-RNAi retarded the Fadu cell proliferation and the metastasis in nude mice and led to up- and down-regulation of the expressions of abundance of genes, especially, the downregulation of the CAPN1 gene. Ionomycin increased the [Ca(2+)]i and decreased the survival rates of Fadu cells in a time-dependent manner. Moreover, Ionomycin resulted in the elevation of CAPN1 mRNA expression in normal Fadu cells and, conversely, had almost no effect on CAPN1 expression in STK33-RNAi cells.

CONCLUSIONS

Findings from this work further validate that STK33 is a potential oncogene and plays an important role in tumorigenesis of HSCC via regulation of numerous genes. In addition, there exists the reciprocal influence between STK33 and [Ca(2+)]i in Fadu cells.

The serine/threonine kinase 33 is present and expressed in palaeognath birds but has become a unitary pseudogene in neognaths about 100 million years ago

Background

Serine/threonine kinase 33 (STK33) has been shown to be conserved across all major vertebrate classes including reptiles, mammals, amphibians and fish, suggesting its importance within vertebrates. It has been shown to phosphorylate vimentin and might play a role in spermatogenesis and organ ontogenesis. In this study we analyzed the genomic locus and expression of stk33 in the class Aves, using a combination of large scale next generation sequencing data analysis and traditional PCR.

Results

Within the subclass Palaeognathae we analyzed the white-throated tinamou (Tinamus guttatus), the African ostrich (Struthio camelus) and the emu (Dromaius novaehollandiae). For the African ostrich we were able to generate a 62,778 bp long genomic contig and an mRNA sequence that encodes a protein showing highly significant similarity to STK33 proteins from other vertebrates. The emu has been shown to encode and transcribe a functional STK33 as well. For the white-throated tinamou we were able to identify 13 exons by sequence comparison encoding a protein similar to STK33 as well.

In contrast, in all 28 neognath birds analyzed, we could not find evidence for the existence of a functional copy of stk33 or its expression. In the genomes of these 28 bird species, we found only remnants of the stk33 locus carrying several large genomic deletions, leading to the loss of multiple exons. The remaining exons have acquired various indels and premature stop codons.

Conclusions

We were able to elucidate and describe the genomic structure and the transcription of a functional stk33 gene within the subclass Palaeognathae, but we could only find degenerate remnants of stk33 in all neognath birds analyzed. This led us to the conclusion that stk33 became a unitary pseudogene in the evolutionary history of the class Aves at the paleognath-neognath branch point during the late cretaceous period about 100 million years ago. We hypothesize that the pseudogenization of stk33 might have become fixed in neognaths due to either genetic redundancy or a non-orthologous gene displacement and present potential candidate genes for such an incident.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1769-9) contains supplementary material, which is available to authorized users.