Persistent EGFR/K-RAS/SIAH pathway activation drives chemo-resistance and early tumor relapse in triple-negative breast cancer

Triple-negative breast cancer(TNBC)is the most aggressive breast cancer subtype.It disproportionately affects BRCA mutation carriers and young women,especially African American(AA)women.Chemoresistant TNBC is a heterogeneous and molecularly unstable disease that challenges our ability to apply personalized therapies.With the approval of immune checkpoint blockade(ICB)for TNBC,the addition of pembrolizumab to systemic chemotherapy has become standard of care(SOC)in neoadjuvant systemic therapy(NST)for high-risk early-stage TNBC.Pembrolizumab plus chemotherapy significantly increased the pathologic complete response(pCR)and improved event-free survival in TNBC.However,clinical uncertainties remain because similarly treated TNBC partial responders with comparable tumor responses to neoadjuvant therapy often experience disparate clinical outcomes.Current methods fall short in accurately predicting which high-risk patients will develop chemo-resistance and tumor relapse.Therefore,novel treatment strategies and innovative new research initiatives are needed.We propose that the EGFR-K-RAS-SIAH pathway activation is a major tumor driver in chemoresistant TNBC.Persistent high expression of SIAH in residual tumors following NACT/NST reflects that the EGFR/K-RAS pathway remains activated(ON),indicating an ineffective response to treatment.These chemoresistant tumor clones persist in expressing SIAH(SIAH^(High/ON))and are linked to early tumor relapse and poorer prognosis.Conversely,the loss of SIAH expression(SIAH^(Low/OFF))in residual tumors post-NACT/NST reflects EGFR/K-RAS pathway inactivation(OFF),indicating effective therapy and chemo-sensitive tumor cells.SIAH^(Low/OFF) signal is linked to tumor remission and better prognosis post-NACT/NST.Therefore,SIAH is well-positioned to become a novel tumor-specific,therapy-responsive,and prognostic biomarker.Potentially,this new biomarker(SIAH^(High/ON))could be used to quantify therapy response,predict chemo-resistance,and identify those patients at the highest risk for tumor relapse and poor survival in TNBC.

Long-noncoding RNAs(lncRNAs) in drug metabolism and disposition, implications in cancer chemo-resistance

Drug metabolism is an orchestrated process in which drugs are metabolized and disposed through a series of specialized enzymes and transporters.Alterations in the expression and/or activity of these enzymes and transporters can affect the bioavailability(pharmacokinetics,or PK)and therapeutic efficacy(pharmacodynamics,or PD)of drugs.Recent studies have suggested that the long non-coding RNAs(IncRNAs)are highly relevant to drug metabolism and drug resistance,including chemoresistance in cancers,through the regulation of drug metabolism and disposition related genes.This review summarizes the regulation of enzymes,transporters,or regulatory proteins involved in drug metabolism by IncRNAs,with a particular emphasis on drug metabolism and chemo-resistance in cancer patients.The perspective strategies to integrate multi-dimensional pharmacogenomics data for future in-depth analysis of drug metabolism related IncRNAs are also proposed.Understanding the role of IncRNAs in drug metabolism will not only facilitate the identification of novel regulatory mechanisms,but also enable the discovery of IncRNA-based biomarkers and drug targets to personalize and improve the therapeutic outcome of patients,including cancer patients.

Overcoming acquired chemo-resistance to gemcitabine: implications from the perspective of multi-modal therapy including surgery for pancreatic cancer

Gemcitabine has been used as a key drug for the treatment of pancreatic ductal adenocarcinoma.Although surgery remains the mainstay for cure of this lethal disease,the effect is quite limited,even for resectable disease,if there is no collaboration with chemotherapy.In the cases with unresectable disease,conversion surgery after a favorable response to chemotherapy might show encouraging results.Potentiation of chemotherapeutic agent is urgently needed in almost all stages of pancreatic cancer.Further efforts must be paid on overcoming chemo-resistance by understanding tumor diversity and developing biomarkers that follow recent success of modified conventional agents by drug delivery technology.

Cisplatin-induced activation of TGF-βsignaling contributes to drug resistance

Growing evidence suggests an association between epithelial-mesenchymal transition(EMT),a hallmark of tumor malignancy,and chemoresistance to a number of anti-cancer drugs.However,the mechanism of EMT induction in the process of acquiring anti-cancer drug resistance remains unclear.To address this issue,we obtained a number of cisplatin-resistant clones from LoVo cells and found that almost all of them lost cell-cell contacts.In these clones,the epithelial marker E-cadherin was downregulated,whereas the mesenchymal marker N-cadherin was upregulated.Moreover,the expression of EMT-related transcription factors,including Slug,was elevated.On the other hand,the upregulation of other mesenchymal marker Vimentin was weak,suggesting that the mesenchymal-like phenotypic changes occurred in these cisplatin-resistant clones.These mesenchymal-like features of cisplatin-resistant clones were partially reversed to parental epithelial-like features by treatment with transforming growth factor-β(TGF-β)receptor kinase inhibitors,indicating that TGF-βsignaling is involved in cisplatin-induced the mesenchymallike phenotypic changes.Moreover,cisplatin was observed to enhance the secretion of TGF-βinto the culture media without influencing TGF-βgene transcription.These results suggest that cisplatin may induce the mesenchymal-like phenotypic changes by enhancing TGF-βsecretion,ultimately resulting in drug resistance.

Striatins and STRIPAK complex partners in clinical outcomes of patients with breast cancer and responses to drug treatment

Objective: Striatins(STRNs) family, which contains three multi-domain scaffolding proteins, are cornerstones of the striatins interacting phosphatase and kinase(STRIPAK) complex. Although the role of the STRIPAK complex in cancer has become recognized in recent years, its clinical significance in breast cancer has not been fully established.Methods: Using a freshly frozen breast cancer tissue cohort containing both cancerous and adjacent normal mammary tissues, we quantitatively evaluated the transcript-level expression of all members within the STRIPAK complex along with some key interacting and regulatory proteins of STRNs. The expression profile of each molecule and the integrated pattern of the complex members were assessed against the clinical-pathological factors of the patients. The Cancer Genome Atlas(TCGA) dataset was used to evaluate the breast cancer patients’ response to chemotherapies. Four human breast cancer cell lines, MDA-MB-231, MDA-MB-361, MCF-7, and SKBR-3, were subsequently adopted for in vitro work.Results: Here we found that high-level expressions of STRIP2, calmodulin, CCM3, MINK1 and SLMAP were respectively associated with shorter overall survival(OS) of patients. Although the similar pattern observed for STRN3, STRN4 and a contrary pattern observed for PPP2CA, PPP2CB and PPPR1A were not significant, the integrated expression profile of STRNs group and PPP2 group members constitutes a highly significant prognostic indicator for OS [P<0.001, hazard ratio(HR)=2.04, 95% confidence interval(95% CI), 1.36-3.07] and disease-free survival(DFS)(P=0.003, HR=1.40, 95% CI, 1.12-1.75). Reduced expression of STRN3 has an influence on the biological functions including adhesiveness and migration. In line with our clinical findings, the breast cancer cells responded to STRN3 knockdown with changes in their chemo-sensitivity, of which the response is also breast cancer subtype dependent.Conclusions: Our results suggest a possible role of the STRIPAK complex in breast cancer development and prognosis. Among the members, the expression profile of STRN3 presents a valuable factor for assessing patients’ responses to drug treatment.

Micro RNA-145 exerts tumor-suppressive and chemoresistance lowering effects by targeting CD44 in gastric cancer

AIM To determine the potential roles of CD4 and micro RNA(mi R)-145 in gastric cancer.METHODS The levels of CD44 and mi R-145 were determined in gastric cancer cells. Quantitative real-time polymerase chain reaction was used to measure to the level of CD44 m RNA. A luciferase reporter assay and western blotting were performed to examine the effect of mi R-145 on CD44 expression. Tumor sphere and MTT assays were carried out to evaluate the self-renewal and chemo-resistance properties of gastric cancer cells.RESULTS The expression of CD44 was greatly increased and mi R-145 was decreased in gastric cancer cells that were highly enriched in cancer stem cells(CSCs). The results demonstrated that mi R-145 regulated CD44 by targeting directly the CD44 3'-untranslated region(3'-UTR). In gastric cancer cells, overexpression of mi R-145 repressed the activity of the CD44 3'-UTR, and disruption of mi R-145/CD44 3'-UTR interactions abrogated the silencing effects. In addition, mi R-145 inhibition stimulated CD44 3'-UTR activity and disruption of mi R-145/CD44 3'-UTR interactions abrogated this stimulatory effect. Enforced CD44 expression greatly increased tumor sphere formation and chemoresistance in gastric cancer cells. Furthermore, the inhibition of CSCs and the chemo-sensitivity of gastric cancer cells treated with mi R-145 were significantly abrogated by overexpression of CD44. CONCLUSION mi R-145 targeting of CD44 plays critical roles in the regulation of tumor growth and chemo-resistance in gastric cancer.

p21-activated kinase signalling in pancreatic cancer: New insights into tumour biology and immune modulation

Pancreatic cancer is one of the most aggressive and lethal malignancies worldwide, with a very poor prognosis and a five-year survival rate less than 8%. This dismal outcome is largely due to delayed diagnosis, early distant dissemination and resistance to conventional chemotherapies. Kras mutation is a well-defined hallmark of pancreatic cancer, with over 95% of cases harbouring Kras mutations that give rise to constitutively active forms of Kras. As important down-stream effectors of Kras, p21-activated kinases(PAKs) are involved in regulating cell proliferation, apoptosis, invasion/migration and chemo-resistance. Immunotherapy is now emerging as a promising treatment modality in the era of personalized anti-cancer therapeutics. In this review, basic knowledge of PAK structure and regulation is briefly summarised and the pivotal role of PAKs in Kras-driven pancreatic cancer is highlighted in terms of tumour biology and chemoresistance. Finally, the involvement of PAKs in immune modulation in the tumour microenvironment is discussed and the potential advantages of targeting PAKs are explored.

Role of gut microbiota-immunity axis in patients undergoing surgery for colorectal cancer:Focus on short and long-term outcomes

Human body is colonized by a huge amount of microorganisms mostly located in the gastrointestinal tract.These dynamic communities,the environment and their metabolites constitute the microbiota.Growing data suggests a causal role of a dysbiotic microbiota in several pathologies,such as metabolic and neurological disorders,immunity dysregulations and cancer,especially the well-studied colorectal cancer development.However,many were preclinical studies and a complete knowledge of the pathogenetic mechanisms in humans is still absent.The gut microbiota can exert direct or indirect effects in different phases of colorectal cancer genesis.For example,Fusobacterium nucleatum promotes cancer through cellular proliferation and some strains of Escherichia coli and Bacteroides fragilis produce genotoxins.However,dysbiosis may also cause a proinflammatory state and the stimulation of a Th17 response with IL-17 and IL-22 secretion that have a pro-oncogenic activity,as demonstrated for Fusobacterium nucleatum.Microbiota has a crucial role in several stages of postoperative course;dysbiosis in fact seems related with surgical site infections and Enterococcus faecalis(and other collagenase-producers microbes)are suggested as a cause of anastomotic leak.Consequently,unbalanced presence of some species,together with altered immune response may also have a prognostic role.Microbiota has also a substantial role in effectiveness of chemotherapy,chemoresistance and in the related side effects.In other words,a complete knowledge of the fine pathological mechanisms of gut microbiota may provide a wide range of new diagnostic tools other than therapeutic targets in the light of tailored medicine.

Regulation of colon cancer recurrence and development of therapeutic strategies

Recurrence of colon cancer still remains a major issue which affects nearly 50% of patients treated by conventional therapeutics. Although the underlying causative factor(s) is not fully understood, development of drug-resistance has been associated with induction of cancer stem or stem-like cells (CSCs) which constitute a small sub-population of tumor cells known to be highly resistant to chemotherapy. In fact, the discovery of CSCs in a variety of tumors (including colon cancer) has changed the view of carcinogenesis and therapeutic strategies. Emerging reports have indicated that to improve patient outcomes, conventional anticancer therapies should be replaced with specifi c approaches targeting CSCs. Thus, therapeutic strategies that specifically target CSCs are being sought to reduce the risk of relapse and metastasis. In order to specifi cally target colon CSCs (while sparing somatic intestinal stem cells), it is critical to identify unique deregulated pathways responsible for self-renewal of CSCs and colon cancer recurrence. Colon CSCs present a unique opportunity to better understand the biology of solid tumors. Thus, a better understanding of the clinical signs and symptoms of colon cancer patients (under-going surgery or chemotherapy) during perioperative periods, along with the underlying regulatory events affecting the stem/progenitor cell self-renewal and differentiation of colon epithelial cells, is of immense importance. In this review we discuss the implication of clinical factors and the emerging role of CSCs during recurrence of colon cancer along with the development of new therapeutic strategies involving the use of natural agents.

Prolonged exposure of colon cancer cells to the epidermal growth factor receptor inhibitor gefitinib(Iressa^(TM))and to the antiangiogenic agent ZD6474:Cytotoxic and biomolecular effects

AIM： To analyze the biological effects of prolonged in vitro exposure of HT-29 and LoVo colon cancer cell lines to gefitinib （Iressa^TM）, an inhibitor of epidermal growth factor receptor （EGFR） activity, and ZD6474, an inhibitor of both KDR and EGFR activities. METHODS： Cells were treated with each drug for up to 2 wk using either a continuous or an intermittent （4 d of drug exposure followed by 3 d of washout each week） schedule. RESULTS： In both cell types, prolonged exposure （up to 14 d） to gefitinib or ZD6474 produced a similar inhibition of cell growth that was persistent and independent of the treatment schedule. The effects on cell growth were associated with a pronounced inhibition of p-EGFR and/ or p-KDR expression. Treatment with gefitinib or ZD6474 also inhibited the expression of EGFR downstream signal molecules, p-Erkl/2 and p-Akt, although the magnitude of these effects varied between treatments and cell lines. Furthermore, expression of the drug resistance-related protein ABCG2 was shown to significantly increase after 14 d of continuous exposure to the two drugs. CONCLUSION： We conclude that long-term exposure of colon cancer cells to gefitinib and ZD6474 does not modify their cytotoxic effects but it might have an effect on sensitivity to classical cytotoxic drugs.

Phosphorylation of Cofilin-1 Enhances Paclitaxel Resistance of Epithelial Ovarian Cancer Cells by Inhibiting Apoptosis

Objective To investigate the molecular mechanism of high phosphorylation levels of cofilin-1(p-CFL-1)associated with paclitaxel resistance in epithelial ovarian cancer(EOC)cells.Methods Cells displaying varying levels of p-CFL-1 and CFL-1 were created by plasmid transfection and shRNA interference.Cell inhibition rate indicating paclitaxel efficacy was assessed by Cell Counting Kit-8(CCK-8)assay.Apoptosis was assessed by flow cytometry and protein levels were detected by western blotting.Quantitative real-time polymerase chain reaction(qRT-PCR)was used to measure the expression levels of phosphokinases and phosphatases of CFL-1.Survival analysis evaluated the correlation between the prognosis of EOC patients and the levels of p-CFL-1 and slingshot-1(SSH-1).Results High levels of p-CFL-1 were observed in EOC cells that survived treatment with high doses of paclitaxel.SKOV3 cell mutants with upregulated p-CFL-1 showed impaired paclitaxel efficacy,as well as decreased apoptosis rates and pro-survival patterns of apoptosis-specific protein expression.Cytoplasmic accumulation of p-CFL-1 inhibited paclitaxel-induced mitochondrial apoptosis.SSH-1 silencing mediated CFL-1 phosphorylation in paclitaxel-resistant SKOV3 cells.Clinically,the high level of p-CFL-1 and the low level of SSH-1 in EOC tissues were closely related to chemotherapy resistance and poor prognosis in EOC patients.Conclusion The SSH-1/p-CFL-1 signaling pathway mediates paclitaxel resistance by apoptosis inhibition in EOC and is expected to be a potential prognostic predictor.

Capilliposide from Lysimachia capillipes promotes terminal differentiations and reverses paclitaxel resistance in A2780T cells of human ovarian cancer by regulating Fos/Jun pathway

Objective:To investigate the potential effect of Lysimachia capillipes capilliposide(LCC)on the chemo sensitivity and the stemness of human ovarian cancer cells.Methods:Cell Counting Kit-8(CCK8)was used to measure the IC50 values.The apoptosis of cells was measured through flow cytometry.Evaluation of the stemness and differentiation markers was performed by the immunoblotting and the immunostaining assays.RNA-seq was performed through the Illumina HiSeq PE150 platform and differentially expressed genes(DEGs)were screened out through the bioinformation analysis.Overexpression or knockdown of Fos gene was achieved by shRNA transfection.Results:Pre-exposure of A2780T cells with 10μg/mL LCC sensitized them to paclitaxel,of which the IC50 value reduced from 8.644μmol/L(95%CI:7.315–10.082μmol/L)to 2.5μmol/L(95%CI:2.233–2.7882μmol/L).Exposure with LCC enhanced the paclitaxel-induced apoptosis and inhibited the colony formation of A2780T cells.LCC exposure reduced the expression of cancer stemness markers,ALDH1,Myd88 and CD44,while promoting that of terminal differentiation markers,NFATc1,Cathepsin K and MMP9.RNAseq analysis revealed that the expressions of FOS and JUN were upregulated in LCC-treated A2780T cells.A2780T cells overexpressing Fos gene displayed increased paclitaxel-sensitivity and reduced cell stemness,and shared common phenotypes with LCC-treated A2780T cells.Conclusion:These findings suggested that LCC promoted terminal differentiations of ovarian cancer cells and sensitized them to paclitaxel through activating the Fos/Jun pathway.LCC might become a novel therapy that targets at cancer stem cells and enhances the chemotherapeutic effect of ovarian cancer treatments.