Novel HER3/MUC4 oncogenic signaling aggravates the tumorigenic phenotypes of pancreatic cancer cells

Several studies have demonstrated that MUC4 is involved in progression and metastasis of pancreatic cancer (PC). Here, we report that HER3/MUC4 interaction in HER2 low cells is critical in driving pancreatic tumorigenesis. Upon HER2 knockdown, we observed elevated expression of HER3 and MUC4 and their interactions, which was confirmed by immunoprecipitation and bioinformatics analyses. In paired human PC tissues, higher percentage of HER3 positivity (10/33, 30.3%; p = 0.001) was observed than HER2 (5/33, 15.1%; p = 0.031), which was further confirmed in spontaneous mice (KPC; Kras^G12D; Trp53^R172H/+; Pdx-Cre) tumors of different weeks. Mechanistically, increased phosphorylation of ERK and expression of PI3K and c-Myc were observed in HER2 knockdown cells, suggesting a positive role for HER3/MUC4 in HER2 low cells. Further, HER2 knockdown resulted in increased proliferation, motility and tumorigenicity of PC cells. Consistently, transient knockdown of HER3 by siRNA in HER2 knockdown cells led to decreased proliferation. These observations led us to conclude that HER3 interacts with MUC4 to promote proliferation in HER2 low PC cells. Further, deficiency of both HER2 and HER3 leads to decreased proliferation of PC cells. Hence targeting these newly identified HER3/MUC4 signals would improve the PC patients survival by intercepting MUC4 mediated oncogenic signaling.     

MUC1与HER2基因在乳腺癌中的研究进展

乳腺癌发病趋势逐年升高,近年来研究发现,MUC1、HER2基因的表达水平能反映乳腺癌的某些生物学特征,与乳腺癌的发生、转移、预后等关系密切。MUC1基因在乳腺癌组织中出现质和量的异常表达。MUC1基因的编码产物成为十分重要的癌标志物,并且是检测乳腺癌淋巴结微小转移的指标。HER2基因在肿瘤组织中呈现过度表达,在正常组织中表达水平较低,被认为是判断乳腺癌预后的独立标记物,其高表达提示乳腺癌细胞的高转移潜能,表现出较高的侵袭性临床病理特征。随着研究的深入,在乳腺癌基因靶点治疗方面也取得了巨大的进展。针对HER2的基因靶点治疗已日趋成熟,Herceptin目前已被证实在乳腺癌的治疗中有巨大的应用前景。MUC1的基因靶点治疗尚处于试验阶段。本文从基因定位、结构、执行功能的分子机制角度对MUC1,HER1在乳腺癌中的作用进行了总结,以便更深入的认识这些基因及其表达产物的生理和病理生理作用,利于乳腺癌的诊断和治疗。     

Prognostic, predictive and therapeutic implications of HER2 in invasive epithelial ovarian cancer

The HER2 oncogene encodes a transmembrane protein partially homologous to epidermal growth factor receptor. This oncogene has been studied mainly in breast cancer where it has prognostic, predictive and therapeutic target value. The expression of HER2 in epithelial ovarian cancer has been less studied. HER2 expression can be determined through IHC, FISH, CISH and ELISA among other tests, with reported positivity frequencies of overexpression varying from 1.8% to 76%. In some studies HER2 overexpression has been associated with advanced stages, poorly differentiated tumors, resistance to chemotherapy and shortened survival. Although trastuzumab is able to produce a low response rate as a single agent in pretreated ovarian cancer patients with overexpression of HER2, its usefulness is limited due to the low frequency of strong expression. To date there is not enough bases for assessment and HER2-based therapies in epithelial ovarian cancer.     

Inhibition of doxorubicin-induced HER3-PI3K-AKT signalling enhances apoptosis of ovarian cancer cells

Resistance to chemotherapy is a serious problem for the successful treatment of ovarian cancer patients but signalling pathways that contribute to this chemoinsensitivity are largely unknown. We demonstrate that the chemotherapeutic drug doxorubicin induces activation of the HER3-PI3K-AKT signalling cascade in ovarian cancer cells. We further show that the induction of this anti-apoptotic signalling pathway is based on upregulated expression of HER3 ligands, their shedding by the metalloprotease ADAM17, and is dependent on the HER2 receptor. The doxorubicin-mediated activation of this important survival cascade can be blocked by the kinase inhibitors lapatinib or erlotinib as well as by the therapeutic monoclonal antibody trastuzumab. Inhibition of the doxorubicin-induced activation of HER3-PI3K-AKT signalling significantly increased apoptosis of ovarian cancer cells. Besides doxorubicin, treatment of cells with cisplatin resulted in activation of the HER3 receptor whereas other chemotherapeutics did not show this effect. The increase in HER3 phosphorylation was detected in well-established ovarian cancer cell lines which originate from patients previously treated with these chemotherapeutic drugs. Based on these results, we postulate that activation of the HER3-PI3K-AKT cascade represents a major mechanism of chemoresistance in ovarian cancer.     

卵巢上皮性肿瘤组织中MUC4、MUC16蛋白的表达及临床意义

目的探讨黏蛋白抗原4（MUC4）及黏蛋白抗原16（MUC16）检测在卵巢癌组织中的表达及临床意义。方法通过免疫组织化学方法检测正常卵巢组织、卵巢良性上皮性肿瘤、卵巢交界性上皮性肿瘤和卵巢癌中MUC4、MUC16的表达。结果在正常卵巢组织、卵巢良性上皮性肿瘤、卵巢交界性上皮性肿瘤和卵巢癌中MUC4的阳性表达率分别为0、10%、36%、80%;MUC16的阳性表达率分别为0、20%、54%、61%;在卵巢癌中,MUC4表达阳性与分化程度、淋巴结转移明显相关（P<0.05）。结论MUC4蛋白在卵巢癌组织中高表达,提示MUC4与卵巢癌的发生发展有关。     

Nuclear HER4 mediates acquired resistance to trastuzumab and is associated with poor outcome in HER2 positive breast cancer

The role of HER4 in breast cancer is controversial and its role in relation to trastuzumab resistance remains unclear. We showed that trastuzumab treatment and its acquired resistance induced HER4 upregulation, cleavage and nuclear translocation. However, knockdown of HER4 by specific siRNAs increased trastuzumab sensitivity and reversed its resistance in HER2 positive breast cancer cells. Preventing HER4 cleavage by a γ-secretase inhibitor and inhibiting HER4 tyrosine kinase activity by neratinib decreased trastuzumab-induced HER4 nuclear translocation and enhanced trastuzumab response. There was also increased nuclear HER4 staining in the tumours from BT474 xenograft mice and human patients treated with trastuzumab. Furthermore, nuclear HER4 predicted poor clinical response to trastuzumab monotherapy in patients undergoing a window study and was shown to be an independent poor prognostic factor in HER2 positive breast cancer. Our data suggest that HER4 plays a key role in relation to trastuzumab resistance in HER2 positive breast cancer. Therefore, our study provides novel findings that HER4 activation, cleavage and nuclear translocation influence trastuzumab sensitivity and resistance in HER2 positive breast cancer. Nuclear HER4 could be a potential prognostic and predictive biomarker and understanding the role of HER4 may provide strategies to overcome trastuzumab resistance in HER2 positive breast cancer.     

SIK2 promotes ovarian cancer cell motility and metastasis by phosphorylating MYLK

Salt‐inducible kinase 2 (SIK2; also known as serine/threonine‐protein kinase SIK2) is overexpressed in several cancers and has been implicated in cancer progression. However, the mechanisms by which SIK2 regulates cancer cell motility, migration and metastasis in ovarian cancer have not been fully discovered. Here, we identify that SIK2 promotes ovarian cancer cell motility, migration and metastasis in vitro and in vivo. Mechanistically, SIK2 regulated cancer cell motility and migration by myosin light chain kinase, smooth muscle (MYLK)‐meditated phosphorylation of myosin light chain 2 (MYL2). SIK2 directly phosphorylated MYLK at Ser343 and activated its downstream effector MYL2, promoting ovarian cancer cell motility and metastasis. In addition, we found that adipocytes induced SIK2 phosphorylation at Ser358 and MYLK phosphorylation at Ser343, enhancing ovarian cancer cell motility. Moreover, SIK2 protein expression was positively correlated with the expression of MYLK‐pS343 in ovarian cancer cell lines and tissues. The co‐expression of SIK2 and MYLK‐pS343 was associated with reduced median overall survival in human ovarian cancer samples. Taken together, SIK2 positively regulates ovarian cancer motility, migration and metastasis, suggesting that SIK2 is a potential candidate for ovarian cancer treatment.     

Lung Adenocarcinoma With MUC4 Expression Is Associated With Smoking Status,HER2 Protein Expression,and Poor Prognosis: Clinicopathologic Analysis of 338 Cases

Background

MUC4 is a transmembrane glycoprotein that plays a role in the cell growth signaling pathway and has been studied in various organ malignancies. This study aimed to analyze MUC4 expression in resected lung adenocarcinomas (ADCs) to define the clinicopathologic characteristics of MUC4-positive cancers.

Usefulness of Salivary and Serum Auto-antibodies Against Tumor Biomarkers HER2 and MUC1 in Breast Cancer Screening

Background: The aim of this work was to investigate if serum and salivary auto antibodies, isotypes IgG and IgM, against HER2 and MUC1 tandem repeat fragments could play a role in breast cancer screening. Materials and Methods: Our case-control study was conducted in breast cancer patients, in early stages (n=29), at the gynecology service, Maternity Souissi Hospital, Rabat, Morocco and healthy woman (n=31). Salivary and serum auto-antibodies against HER2 and MUC1 (tandem repeat) were assessed by enzyme-linked immunosorbent assay (ELISA) and compared between patients and healthy women using the Mann Whitney U test. A P-value <0.05 was considered to be statistically significant. Results: Our data showed higher expression of all serum and salivary autoantibodies in patients as compared to healthy women p<0.05. However, serum IgM anti-MUC1 expression did not show a significant difference between cases and controls (p=0.79). Similarly, salivary IgG anti-HER2 expression did not differ (p=0.15). The correlation between the different isotypes of antibodies revealed that the highest correlation was between salivary IgG anti-HER2 and salivary IgG anti- MUC1(r=0.65). In fact, we have found in saliva the correlation between autoantibodies anti-MUC1 and anti HER2 more important than in serum (r=0.59 and r=0. 55). However, the correlation between serum and saliva values for all antibodies was weak. Conclusions: Autoantibodies against HER2 and MUC1 may provide a useful approach in breast cancer screening when using both serum and saliva values.     

Pancreatic cancer cells resistance to gemcitabine: the role of MUC4 mucin

Background:

A major obstacle to the successful management of pancreatic cancer is to acquire resistance to the existing chemotherapeutic agents. Resistance to gemcitabine, the standard first-line chemotherapeutic agent for advanced and metastatic pancreatic cancer, is mainly attributed to an altered apoptotic threshold in the pancreatic cancer. The MUC4 transmembrane glycoprotein is aberrantly overexpressed in the pancreatic cancer and recently, has been shown to increase pancreatic tumour cell growth by the inhibition of apoptosis.

Methods:

Effect of MUC4 on pancreatic cancer cells resistance to gemcitabine was studied in MUC4-expressing and MUC4-knocked down pancreatic cancer cell lines after treatment with gemcitabine by Annexin-V staining, DNA fragmentation assay, assessment of mitochondrial cytochrome c release, immunoblotting and co-immunoprecipitation techniques.

Results:

Annexin-V staining and DNA fragmentation experiment demonstrated that MUC4 protects CD18/HPAF pancreatic cancer cells from gemcitabine-induced apoptosis. In concert with these results, MUC4 also attenuated mitochondrial cytochrome c release and the activation of caspase-9. Further, our results showed that MUC4 exerts anti-apoptotic function through HER2/extracellular signal-regulated kinase-dependent phosphorylation and inactivation of the pro-apoptotic protein Bad.

Conclusion:

Our results elucidate the function of MUC4 in imparting resistance to pancreatic cancer cells against gemcitabine through the activation of anti-apoptotic pathways and, thereby, promoting cell survival.     

粘蛋白MUC1和MUC2在胃癌组织中的表达及其预后意义

目的 :探讨粘蛋白MUC1和MUC2在胃癌组织中的表达及意义。方法 :采用免疫组织化学法的SP法检测 86例胃癌组织及 2 0例人正常胃粘膜中的MUC1和MUC2的表达。结果 :在正常胃粘膜中MUC1阳性表达率为 10 0 % ,而MUC2无阳性表达。在胃癌组织中MUC1和MUC2的表达率分别为 5 8 14 %和 6 3 95 %。胃癌组织中MUC1和MUC2的表达与肿瘤大小、浸润深度及分化程度无关 (P >0 0 5 ) ,但Ⅰ～Ⅱ期、淋巴结无转移组MUC1的表达明显比Ⅲ～Ⅳ期、淋巴结转移组低 ,而MUC2表达明显增高 (P <0 0 1)。Kaplan Meier分析发现MUC1高表达和MUC2低表达患者的生存时间明显低于MUC1低表达和MUC2高表达患者 (P <0 0 1)。结论 :MUC1和MUC2可预示胃癌的转移潜能 ,两者联合表达可作为评估预后的参考指标。     

Human MUC4 mucin induces ultra-structural changes and tumorigenicity in pancreatic cancer cells

MUC4 is a type-1 transmembrane glycoprotein and is overexpressed in many carcinomas. It is a heterodimeric protein of 930 kDa, composed of a mucin-type subunit, MUC4alpha, and a membrane-bound growth factor-like subunit, MUC4beta. MUC4 mRNA contains unique 5' and 3' coding sequences along with a large variable number of tandem repeat (VNTR) domain of 7-19 kb. A direct association of MUC4 overexpression has been established with the degree of invasiveness and poor prognosis of pancreatic cancer. To understand the precise role of MUC4 in pancreatic cancer, we engineered a MUC4 complementary DNA construct, mini-MUC4, whose deduced protein (320 kDa) is comparable with that of wild-type MUC4 (930 kDa) but represents only 10% of VNTR. Stable ectopic expression of mini-MUC4 in two human pancreatic cancer cell lines, Panc1 and MiaPaCa, showed that MUC4 minigene expression follows a biosynthesis and localisation pattern similar to the wild-type MUC4. Expression of MUC4 resulted in increased growth, motility, and invasiveness of the pancreatic cancer cells in vitro. Ultra-structural examination of MUC4-transfected cells showed the presence of increased number and size of mitochondria. The MUC4-expressing cells also demonstrated an enhanced tumorigenicity in an orthotopic xenograft nude mice model, further supporting a direct role of MUC4 in inducing the cancer properties. In conclusion, our results suggest that MUC4 promotes tumorigenicity and is directly involved in growth and survival of the cancer cells.     

HER4与浸润性乳腺癌预后的相关性分析

目的检测HER4在浸润性乳腺癌组织中的表达水平,探讨其表达与临床病理学参数及预后之间的关系。方法58例浸润性乳腺癌病人中,5年内复发组32例,5年无复发组26例,采用免疫组化法检测病理标本的ER、HER2及HER4表达水平,随访局部控制及生存情况。结果ER、HER2、HER4在浸润性乳腺癌中的表达率分别为53．4％（31／58）、24．1％（14／58）和32．8％（19／58）,5年内无复发组的HER4阳性表达率显著高于5年内复发组（P=0．05）,HER2阳性表达率显著低于5年内复发组（P=0．043）,两组的ER表达率无统计学差异（P=0．866）。全组HER4阳性表达组无复发生存时间显著长于HER4阴性组（P=0．023）,OS也有延长趋势（P=0．057）。HER2阴性表达组的RFS（P=0．048）与OS（P=0．02）皆显著长于阳性表达组。HER2与HER4的联合表达情况与RFS和OS密切相关,HER2-／HER4＋组RFS（P=0．016）和OS（P=0．014）显著长于其他各组。多因素分析显示转移淋巴结数、HER2及HER4表达情况是OS的独立影响因素,而淋巴结数和HER4表达情况是RFS的独立影响因素。结论HER4是浸润性乳腺癌的独立预后影响因素,其阳性表达者具有较好的临床预后。     

In ovarian cancer the prognostic influence of HER2/neu is not dependent on the CXCR4/SDF-1 signalling pathway

HER2/neu overexpression is a driving force in the carcinogenesis of several human cancers. In breast cancer the prognostic influence of HER2/neu was shown to be at least partly based on increased metastatic potential mediated by the chemokine-chemokine receptor pair SDF-1(CXCL12)/CXCR4. We wanted to evaluate the influence of HER2/neu on ovarian cancer prognosis and to investigate whether compromised survival would correlate with CXCR4 expression and/or SDF-1 abundance. Therefore, we analysed HER2/neu, CXCR4, and SDF-1 in 148 ovarian tumour samples by means of immunohistochemistry on tissue microarrays. Overexpression of HER2/neu was found in 27.6% of ovarian cancer tissues and in 15% of ovarian borderline tumours. In ovarian cancer patients, overexpression of HER2/neu correlated closely with overall survival (univariate hazard ratio (HR) 2.59, P=0.005; multiple corrected HR 1.92, P=0.074). In contrast, CXCR4 expression and SDF-1 abundance had no impact on overall survival, and both parameters were not correlated with HER2/neu expression. As expected, cytoplasmic CXCR4 expression and SDF-1 abundance correlated closely (P<0.0001). Our results confirm a univariate influence of HER2/neu expression on overall survival, which was completely independent of the expression of CXCR4 and the abundance of SDF-1, implying significant differences between the HER2/neu downstream pathways in ovarian cancer compared with breast cancer.     

癌基因HER2与乳腺癌的治疗

ＨＥＲ２／ｃ－ｅｒｂＢ２是编码一种生长因子受体（ｐ１８５＾ＨＥＲ２）的癌基因,研究发现ＨＥＲ２基因的扩增和表达对于乳腺癌的预后具有重要意义,对于乳腺癌的治疗亦有重要的指导作用。针对ｐ１８５＾ＨＥＲ２的单克隆抗体Ｈｅｒｃｅｐｔｉｎ能有效抑制ｐ１８５＾ＨＥＲ２高表达的乳腺癌细胞的生长,为乳腺癌的治疗提供了一种新的手段。而针对ＨＥＲ２表达产物ｐ１８５＾ＨＥＲ２的疫苗的研究将可能是乳腺癌治疗的一个重要的突     

Downregulation of cell surface CA125/MUC16 induces epithelial-to-mesenchymal transition and restores EGFR signalling in NIH:OVCAR3 ovarian carcinoma cells

Background:

Epithelial ovarian cancer (EOC) cells are prone to metastasise throughout the peritoneal cavity. The epithelial-to-mesenchymal transition (EMT) is a necessary step towards metastatic tumour progression. CA125/MUC16 mucin is a high-molecular-weight glycoprotein overexpressed in the majority of serous carcinomas, suggesting a possible role in the pathogenesis of these cancers.

Methods:

The role of CA125/MUC16 in EMT was investigated using single-chain antibody-mediated knockdown of cell surface CA125/MUC16 in overexpressing EOC NIH:OVCAR3 cells.

Results:

CA125/MUC16 knockdown was associated with morphological alterations along with decreased surface expression of epithelial markers (E-cadherin, cytokeratin-18) and increased expression of mesenchymal markers (N-cadherin, vimentin). Co-immunoprecipitation experiments revealed that CA125/MUC16 binds to E-cadherin and β-catenin complexes. The in vitro studies showed disruption of cell–cell junctions, enhanced motility, migration and invasiveness in CA125/MUC16 knockdown cells. Enhanced epidermal growth factor receptor (EGFR) activation was observed in CA125/MUC16 knockdown cells along with increased Akt and ERK1/2 phosphorylation, which are downstream effectors of EGFR, and increased MMP-2 and MMP-9 expression and activities. Epidermal growth factor receptor inhibition strongly inhibited the motility of CA125/MUC16 knockdown cells.

Conclusions:

Our findings suggest that CA125/MUC16 plays a role in EMT, presumably through its interaction with E-cadherin and β-catenin complexes and by modulating EGFR and its downstream signalling pathway in NIH:OVCAR3 cells.     

Photochemical activation of MH3-B1/rGel: a HER2-targeted treatment approach for ovarian cancer

HER2-targeted therapy has been shown to have limited efficacy in ovarian cancer despite frequent overexpression of this receptor. Photochemical internalization (PCI) is a modality for cytosolic drug delivery, currently undergoing clinical evaluation. In the present project we studied the application of PCI in combination with the HER2-targeted recombinant fusion toxin, MH3-B1/rGel, for the treatment of ovarian cancer. The SKOV-3 cell line, resistant to trastuzumab- and MH3-B1/rGel- monotherapy, was shown to respond strongly to PCI of MH3-B1/rGel to a similar extent as observed for the treatment-sensitive SK-BR-3 breast cancer cells. Extensive hydrolytic degradation of MH3-B1/rGel in acidic endocytic vesicles was indicated as the mechanism of MH3-B1/rGel resistance in SKOV-3 cells. This was shown by the positive Pearson''s correlation coefficient between Alexa488-labeled MH3-B1/rGel and Lysotracker in SKOV-3 cells in contrast to the negative Pearson''s correlation coefficient in SK-BR-3 cells. The application of PCI to induce the release of MH3-B1/rGel was also demonstrated to be effective on SKOV-3 xenografts. Application of PCI with MH3-B1/rGel was further found highly effective in the HER2 expressing HOC-7 and NuTu-19 ovarian cancer cell lines. The presented results warrant future development of PCI in combination with MH3-B1/rGel as a novel therapeutic approach in preclinical models of ovarian cancer.     

Calpain4 is required for activation of HER2 in breast cancer cells exposed to trastuzumab and its suppression decreases survival and enhances response

Overactivation of HER2 and crosstalk of other HER family members contribute to a survival pathway of breast cancer cells exposed to trastuzumab, the therapeutic inhibitor of HER2 and thus, decrease response and promote resistance. We have explored the involvement of the intracellular cysteine protease calpain4, the common partner of isoforms calpain1 and calpain2, in the regulation of cell survival and trastuzumab-response. Increase of calpain4 expression and isoform activities were detected in breast cancer cells and HER2-positive tumors. Molecular analyses of parent and resistant cells suggested that perturbation of regulations, induced by calpain4 and of activities of HER2 and HER3, was associated with trastuzumab-resistance. The suppression of calpain4 destabilized calpain1 and calpain2, however, did not prevent the activation of HER2 and HER3 or cell proliferation in the absence of trastuzumab. To understand the significance, the survival of parent and trastuzumab-resistant cells in which calpain4 was suppressed, was assessed in the presence of trastuzumab; survival in each cell type was decreased and associated with a loss of HER2 and HER3 activity. Taken together, by contributing to the activation and the crosstalk of HER2, calpain4 promotes the survival pathway of breast cancer cells, and therefore, its suppression enhances trastuzumab-response and decreases resistance.     

Feedback activation of STAT3 mediates trastuzumab resistance via upregulation of MUC1 and MUC4 expression

Although HER2-targeting antibody trastuzumab confers a substantial benefit for patients with HER2-overexpressing breast and gastric cancer, overcoming trastuzumab resistance remains a large unmet need. In this study, we revealed a STAT3-centered positive feedback loop that mediates the resistance of trastuzumab. Mechanistically, chronic exposure of trastuzumab causes the upregulation of fibronection (FN), EGF and IL-6 in parental trastuzumab-sensitive breast and gastric cells and convergently leads to STAT3 hyperactivation. Activated STAT3 enhances the expression of FN, EGF and IL-6, thus constituting a positive feedback loop which amplifies and maintains the STAT3 signal; furthermore, hyperactivated STAT3 signal promotes the expression of MUC1 and MUC4, consequently mediating trastuzumab resistance via maintenance of persistent HER2 activation and masking of trastuzumab binding to HER2 respectively. Genetic or pharmacological inhibition of STAT3 disrupted STAT3-dependent positive feedback loop and recovered the trastuzumab sensitivity partially due to increased apoptosis induction. Combined trastuzumab with STAT3 inhibition synergistically suppressed the growth of the trastuzumab-resistant tumor xenografts in vivo. Taken together, our results suggest that feedback activation of STAT3 constitutes a key node mediating trastuzumab resistance. Combinatorial targeting on both HER2 and STAT3 may enhance the efficacy of trastuzumab or other HER2-targeting agents in HER2-positive breast and gastric cancer.