Cyclopamine increases the radiosensitivity of human pancreatic cancer cells by regulating the DNA repair signal pathway through an epidermal growth factor receptor-dependent pathway

Phase II, Single-Arm Trial of Induction and Concurrent Vismodegib With Curative-Intent Radiation Therapy for Locally Advanced, Unresectable Basal Cell Carcinoma

PURPOSE

Locally advanced, unresectable basal cell carcinoma (LA BCC) can be treated with radiation therapy (RT), but locoregional control (LRC) rates are unsatisfactory. Vismodegib is a hedgehog pathway inhibitor (HPI) active in BCC that may radiosensitize BCC. We evaluated the combination of vismodegib and RT for patients with LA BCC.

METHODS

In this multicenter, single-arm, phase II study, patients with unresectable LA BCC received 12 weeks of induction vismodegib, followed by 7 weeks of concurrent vismodegib and RT. The primary end point was LRC rate at 1 year after the end of treatment. Secondary end points included objective response, progression-free survival (PFS), overall survival (OS), safety, and patient-reported quality of life (PRQOL).

RESULTS

Twenty-four patients received vismodegib; five were unable to complete 12 weeks of induction therapy. LRC was achieved in 91% (95% CI, 68 to 98) of patients at 1 year. The response rate was 63% (95% CI, 38 to 84) after induction vismodegib and 83% (95% CI, 59 to 96) after concurrent vismodegib and RT. With a median follow-up of 5.7 years, 1-year PFS and OS rates were 100% and 96%, and at 5 years PFS and OS rates were 78% and 83%, respectively. Distant metastasis or BCC-related death has not been observed. The most frequent treatment-related adverse events (AEs) were dysgeusia, fatigue, and myalgias occurring in 83%, 75%, and 75% of patients. No grade 4 to 5 treatment-related AEs occurred. PRQOL demonstrated clinically meaningful improvements in all subscales, with emotions and functioning improvements persisting for a year after the end of treatment.

CONCLUSION

In patients with unresectable LA BCC, the combination of vismodegib and RT yielded high rates of LRC and PFS and durable improvements in PRQOL.

Targeting hedgehog-driven mechanisms of drug-resistant cancers

Due to the cellular plasticity that is inherent to cancer, the acquisition of resistance to therapy remains one of the biggest obstacles to patient care. In many patients, the surviving cancer cell subpopulation goes on to proliferate or metastasize, often as the result of dramatically altered cell signaling and transcriptional pathways. A notable example is the Hedgehog (Hh) signaling pathway, which is a driver of several cancer subtypes and aberrantly activated in a wide range of malignancies in response to therapy. This review will summarize the field's current understanding of the many roles played by Hh signaling in drug resistance and will include topics such as non-canonical activation of Gli proteins, amplification of genes which promote tolerance to chemotherapy, the use of hedgehog-targeted drugs and tool compounds, and remaining gaps in our knowledge of the transcriptional mechanisms at play.

Mir-326 potentiates radiosensitivity of cervical squamous cell carcinoma through downregulating SMO expression in the Hedgehog signaling pathway

BACKGROUND

Radiotherapy resistance affects the therapeutic effect of cervical squamous cell carcinoma (CSCC). Smoothened (Smo) is an anticancer target of the Hedgehog (Hh) pathway and its mutation is related to drug resistance.

OBJECTIVE

To explore the roles of miR-326 and Smoothened (SMO) on radiation resistance in patients with cervical carcinoma.

METHODS

Expression of miR-326 and SMO in cervical cancer tissue and radioresistant cell lines were analyzed. The radiation response with the expression of miR-326 was evaluated in tissue and cells. Bioinformatics analysis and literature review were performed to explore the target of miR-326. The regulation of miR-326 to SMO mRNA was verified through the dual-luciferase reporter assay.

RESULTS

Patients with poor radiation response have lower miR-326 and higher SMO expression. Upregulation of miR-326 decreased SMO expression and its downstream proteins but does not affect the proliferation of CSCC cells. The upregulation of miR-326 increased radiation sensitivity of the CSCC cell through downregulating SMO and its downstream proteins in the Hedgehog (Hh) signaling pathway.

CONCLUSIONS

miR-326 may predict the treatment response to radiation, and upregulating miR-326 may improve the treatment response to radiation.

Defining the Role of GLI/Hedgehog Signaling in Chemoresistance: Implications in Therapeutic Approaches

Insight into cancer signaling pathways is vital in the development of new cancer treatments to improve treatment efficacy. A relatively new but essential developmental signaling pathway, namely Hedgehog (Hh), has recently emerged as a major mediator of cancer progression and chemoresistance. The evolutionary conserved Hh signaling pathway requires an in-depth understanding of the paradigm of Hh signaling transduction, which is fundamental to provide the necessary means for the design of novel tools for treating cancer related to aberrant Hh signaling. This review will focus substantially on the canonical Hh signaling and the treatment strategies employed in different studies, with special emphasis on the molecular mechanisms and combination treatment in regard to Hh inhibitors and chemotherapeutics. We discuss our views based on Hh signaling's role in regulating DNA repair machinery, autophagy, tumor microenvironment, drug inactivation, transporters, epithelial-to-mesenchymal transition, and cancer stem cells to promote chemoresistance. The understanding of this Achilles' Heel in cancer may improve the therapeutic outcome for cancer therapy.

Inhibition of CAL27 Oral Squamous Carcinoma Cell by Targeting Hedgehog Pathway With Vismodegib or Itraconazole

Oral Squamous Cell Carcinoma (OSCC) presents an important challenge for the health systems worldwide. Thus, unraveling the biological mechanisms involved in OSCC pathogenesis is essential to the discovery of new drugs with anticancer potential. The Hedgehog (HH) pathway has shown promising results as a therapeutic target both in vitro and in vivo. This study aimed to investigate the effects of vismodegib and itraconazole on the expression of Hedgehog (HH) genes (PTCH1, SMO, and GLI1), cell cycle and cell death in OSCC cells. Alamar Blue assay was used to assess the cytotoxicity of vismodegib and itraconazole in a panel of oral cancer cell lines, including CAL27. The expression of HH signaling components after treatment with vismodegib and itraconazole, at concentrations of 25 or 50 μg/ml was evaluated by qPCR. Cell cycle and apoptosis were evaluated by flow cytometry after 72 h treatment with 50 μg/ml of vismodegib or itraconazole. HH signaling was activated in OSCC cell lines CAL27, SCC4, SCC9, and HSC3. Vismodegib and itraconazole significantly reduced CAL27 cell viability after 48 h of treatment. Gene expression of PTCH1, SMO, and GLI1 decreased in response to 24 h of treatment with vismodegib or itraconazole. Furthermore, CAL27 cells exhibited alterations in morphology, cell size, and cellular granularity. An increase in the DNA fragmentation was observed after treatment and both inhibitors induced apoptosis after 72 h. In conclusion, SMO inhibitors vismodegib and itraconazole demonstrably reduced the expression of HH genes in CAL27 OSCC cell line. In addition, treatment with vismodegib and itraconazole reduced cellular viability and altered the morphology of CAL27 cells, and also induced apoptosis.

Combination Therapy With Charged Particles and Molecular Targeting: A Promising Avenue to Overcome Radioresistance

Radiotherapy plays a central role in the treatment of cancer patients. Over the past decades, remarkable technological progress has been made in the field of conventional radiotherapy. In addition, the use of charged particles (e.g., protons and carbon ions) makes it possible to further improve dose deposition to the tumor, while sparing the surrounding healthy tissues. Despite these improvements, radioresistance and tumor recurrence are still observed. Although the mechanisms underlying resistance to conventional radiotherapy are well-studied, scientific evidence on the impact of charged particle therapy on cancer cell radioresistance is restricted. The purpose of this review is to discuss the potential role that charged particles could play to overcome radioresistance. This review will focus on hypoxia, cancer stem cells, and specific signaling pathways of EGFR, NFκB, and Hedgehog as well as DNA damage signaling involving PARP, as mechanisms of radioresistance for which pharmacological targets have been identified. Finally, new lines of future research will be proposed, with a focus on novel molecular inhibitors that could be used in combination with charged particle therapy as a novel treatment option for radioresistant tumors.

Radiation Sensitization of Basal Cell and Head and Neck Squamous Cell Carcinoma by the Hedgehog Pathway Inhibitor Vismodegib

Vismodegib, an inhibitor of the Hedgehog signaling pathway, is an approved drug for monotherapy in locally advanced or metastatic basal cell carcinoma (BCC). Data on combined modality treatment by vismodegib and radiation therapy, however, are rare. In the present study, we examined the radiation sensitizing effects of vismodegib by analyzing viability, cell cycle distribution, cell death, DNA damage repair and clonogenic survival in three-dimensional cultures of a BCC and a head and neck squamous cell carcinoma (HNSCC) cell line. We found that vismodegib decreases expression of the Hedgehog target genes glioma-associated oncogene homologue (GLI1) and the inhibitor of apoptosis protein (IAP) Survivin in a cell line- and irradiation-dependent manner, most pronounced in squamous cell carcinoma (SCC) cells. Furthermore, vismodegib significantly reduced proliferation in both cell lines, while additional irradiation only slightly further impacted on viability. Analyses of cell cycle distribution and cell death induction indicated a G1 arrest in BCC and a G2 arrest in HNSCC cells and an increased fraction of cells in SubG1 phase following combined treatment. Moreover, a significant rise in the number of phosphorylated histone-2AX/p53-binding protein 1 (γH2AX/53BP1) foci in vismodegib- and radiation-treated cells was associated with a significant radiosensitization of both cell lines. In summary, these findings indicate that inhibition of the Hedgehog signaling pathway may increase cellular radiation response in BCC and HNSCC cells.

Gli1 promotes transforming growth factor-beta1- and epidermal growth factor-induced epithelial to mesenchymal transition in pancreatic cancer cells

BACKGROUND

The Hedgehog signaling pathway and its key target effector Gli1 are linked closely to the development of the epithelial to mesenchymal transition (EMT) in many cancers. The definite function of Gli1 in regulating the EMT of pancreatic cancer (PC), however, is still unclear.

METHODS

At the cell and tissue levels, we investigated the role of Gli1 in the initiation of EMT in PC with and without external stimulus treatments.

RESULTS

The immunohistochemistry results showed that Gli1 was associated positively with MMP9 but not with E-cad or Vimentin. Gli1 expression was associated positively with tumor T (P = .025) and Union for International Cancer Control stage (P = .032), whereas MMP9 expression was associated positively with lymph node metastasis (P = .017) and Union for International Cancer Control stage (P = .006). Furthermore, patients with Gli1 and MMP9 coexpression had poor overall survival (P = .015). Silencing of Gli1 alone without external stimulus had no effect on EMT but inhibited transforming growth factor-beta1 (TGFβ1)- and epidermal growth factor (EGF)-induced EMT in PANC-1, AsPC-1, and BxPC-3 PC cell lines, along with the inhibition of TGFβ1- and EGF-induced EMT-like cell morphology and invasion, down-regulation of E-cad, and up-regulation of MMP9 and Vimentin in those 3 cell lines, respectively.

CONCLUSION

Gli1 silencing alone has no effect on EMT initiation; however, it exerts a protumor role in the aggressive invasion of PC cells by promoting TGFβ1- and EGF-induced EMT.

The Impact of Hedgehog Signaling Pathway on DNA Repair Mechanisms in Human Cancer

Defined cellular mechanisms have evolved that recognize and repair DNA to protect the integrity of its structure and sequence when encountering assaults from endogenous and exogenous sources. There are five major DNA repair pathways: mismatch repair, nucleotide excision repair, direct repair, base excision repair and DNA double strand break repair (including non-homologous end joining and homologous recombination repair). Aberrant activation of the Hedgehog (Hh) signaling pathway is a feature of many cancer types. The Hh pathway has been documented to be indispensable for epithelial-mesenchymal transition, invasion and metastasis, cancer stemness, and chemoresistance. The functional transcription activators of the Hh pathway include the GLI proteins. Inhibition of the activity of GLI can interfere with almost all DNA repair types in human cancer, indicating that Hh/GLI functions may play an important role in enabling tumor cells to survive lethal types of DNA damage induced by chemotherapy and radiotherapy. Thus, Hh signaling presents an important therapeutic target to overcome DNA repair-enabled multi-drug resistance and consequently increase chemotherapeutic response in the treatment of cancer.

Roles of EGFR and KRAS and their downstream signaling pathways in pancreatic cancer and pancreatic cancer stem cells

Pancreatic cancer is currently the fourth most common cancer, is increasing in incidence and soon will be the second leading cause of cancer death in the USA. This is a deadly malignancy with an incidence that approximates the mortality with 44,000 new cases and 36,000 deaths each year. Surgery, although only modestly successful, is the only curative option. However, due the locally aggressive nature and early metastasis, surgery can be performed on less than 20% of patients. Cytotoxic chemotherapy is palliative, has significant toxicity and improves survival very little. Thus new treatment paradigms are needed desperately. Due to the extremely high frequency of KRAS gene mutations (>90%) detected in pancreatic cancer patients, the roles of the epidermal growth factor receptor (EGFR), Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTORC1/GSK-3 pathways have been investigated in pancreatic cancer for many years. Constitutively active Ras can activate both of these pathways and there is cross talk between Ras and EGFR which is believed to be important in driving metastasis. Mutant KRAS may also drive the expression of GSK-3 through Raf/MEK/ERK-mediated effects on GSK-3 transcription. GSK-3 can then regulate the expression of NF-kappaB which is important in modulating pancreatic cancer chemoresistance. While the receptors and many downstream signaling molecules have been identified and characterized, there is still much to learn about these pathways and how their deregulation can lead to cancer. Multiple inhibitors to EGFR, PI3K, mTOR, GSK-3, Raf, MEK and hedgehog (HH) have been developed and are being evaluated in various cancers. Current research often focuses on the role of these pathways in cancer stem cells (CSC), with the goal to identify sites where therapeutic resistance may develop. Relatively novel fields of investigation such as microRNAs and drugs used for other diseases e.g., diabetes, (metformin) and malaria (chloroquine) have provided new information about therapeutic resistance and CSCs. This review will focus on recent advances in the field and how they affect pancreatic cancer research and treatment.

Cyclopamine-loaded core-cross-linked polymeric micelles enhance radiation response in pancreatic cancer and pancreatic stellate cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers. Cyclopamine (CPA), a potent inhibitor for sonic hedgehog pathway (SHH), shows great promises in PDAC treatment, including the disruption of tumor-associated stroma, and enhancement of radiation therapy. However, CPA is insoluble in water and therefore requires a nanometric delivery platform to achieve satisfactory performance. We herein encapsulated CPA in a core-cross-linked polymeric micelle system (M-CPA). M-CPA was combined with Cs-137 radiation and evaluated in vitro in PDAC cell lines and a human pancreatic stellate cell line. The results showed that M-CPA had higher cytotoxicity than CPA, abolished Gli-1 expression (a key component of SHH), and enhanced the radiation therapy of Cs-137. M-CPA radiosensitization correlated with its ability to disrupt the repair of radiation-induced DNA damage. These findings indicate that the combination therapy of M-CPA and radiation is an effective strategy to simultaneously treat pancreatic tumors and tumor-associated stroma.

Chemoradiation therapy using cyclopamine-loaded liquid-lipid nanoparticles and lutetium-177-labeled core-crosslinked polymeric micelles

Cyclopamine (CPA), a potent inhibitor of the Hedgehog pathway, has produced promising anticancer results in a number of preclinical studies. CPA has also been found to enhance tumor response to radiation therapy. However, CPA is water insoluble. A drug delivery system suitable for systemic administration of CPA is needed before CPA can be considered for clinical translation. We hypothesized that CPA solubilized in a liquid-lipid nanoparticle system (CPA-LLP) for intravenous injection would have desirable pharmacokinetic properties and increased anticancer efficacy. We further hypothesized that CPA-LLP would enhance the response of tumor cells to targeted radiotherapy delivered selectively through intratumoral injection of lutetium-177 bound to core-crosslinked polymeric micelles (CCPM-(177)Lu). We tested the combination therapy in 4T1 murine breast cancer and Miapaca-2 human pancreatic adenocarcinoma models. The results showed that CPA-LLP had higher antitumor cytotoxicity than free CPA (IC50 values [mean±SEM]: 2.7±0.2μM vs. 11.3±1.2μM against 4T1 cells; 1.8±0.2 vs. 17.1±1.26μM against Miapaca-2 cells; p<0.0001). In both cell lines, CPA-LLP resulted in significantly lower clonogenicity than free CPA (p<0.05). Moreover, in both cell lines, CPA-LLP significantly enhanced the cell response to CCPM-(177)Lu radiotherapy as measured by clonogenic assay (p<0.05). In 4T1 and Miapaca-2 mouse xenograft models, the combination of CPA-LLP and CCPM-(177)Lu delayed tumor growth more than either monotherapy did alone. In the 4T1 tumor model, tumor size at 16days after treatment was significantly smaller with the combination therapy than with all the other treatments. In the Miapaca-2 model, the combination therapy resulted in the highest rate of mouse survival and prevented tumor relapse. In conclusion, the combination of CPA-LLP and CCPM-(177)Lu was an effective strategy for treating breast and pancreatic cancer and deserves further investigation.

Liver renewal: detecting misrepair and optimizing regeneration

Cirrhosis and liver cancer, the main causes of liver-related morbidity and mortality, result from defective repair of liver injury. This article summarizes rapidly evolving knowledge about liver myofibroblasts and progenitors, the 2 key cell types that interact to orchestrate effective repair, because deregulation of these cells is likely to be central to the pathogenesis of both cirrhosis and liver cancer. We focus on cirrhosis pathogenesis because cirrhosis is the main risk factor for primary liver cancer. Emerging evidence suggests that the defective repair process has certain characteristics that might be exploited for biomarker development. Recent findings in preclinical models also indicate that the newly identified cellular and molecular targets are amenable to therapeutic manipulation. Thus, recent advances in our understanding about key cell types and fundamental mechanisms that regulate liver regeneration have opened new avenues to improve the outcomes of liver injury.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01899859.