Induction of Acquired Resistance towards EGFR Inhibitor Gefitinib in a Patient-Derived Xenograft Model of Non-Small Cell Lung Cancer and Subsequent Molecular Characterization

Preclinical Anticipation of On- and Off-Target Resistance Mechanisms to Anti-Cancer Drugs: A Systematic Review

The advent of targeted therapies has led to tremendous improvements in treatment options and their outcomes in the field of oncology. Yet, many cancers outsmart precision drugs by developing on-target or off-target resistance mechanisms. Gaining the ability to resist treatment is the rule rather than the exception in tumors, and it remains a major healthcare challenge to achieve long-lasting remission in most cancer patients. Here, we discuss emerging strategies that take advantage of innovative high-throughput screening technologies to anticipate on- and off-target resistance mechanisms before they occur in treated cancer patients. We divide the methods into non-systematic approaches, such as random mutagenesis or long-term drug treatment, and systematic approaches, relying on the clustered regularly interspaced short palindromic repeats (CRISPR) system, saturated mutagenesis, or computational methods. All these new developments, especially genome-wide CRISPR-based screening platforms, have significantly accelerated the processes for identification of the mechanisms responsible for cancer drug resistance and opened up new avenues for future treatments.

Generation, evolution, interfering factors, applications, and challenges of patient-derived xenograft models in immunodeficient mice

Establishing appropriate preclinical models is essential for cancer research. Evidence suggests that cancer is a highly heterogeneous disease. This follows the growing use of cancer models in cancer research to avoid these differences between xenograft tumor models and patient tumors. In recent years, a patient-derived xenograft (PDX) tumor model has been actively generated and applied, which preserves both cell-cell interactions and the microenvironment of tumors by directly transplanting cancer tissue from tumors into immunodeficient mice. In addition to this, the advent of alternative hosts, such as zebrafish hosts, or in vitro models (organoids and microfluidics), has also facilitated the advancement of cancer research. However, they still have a long way to go before they become reliable models. The development of immunodeficient mice has enabled PDX to become more mature and radiate new vitality. As one of the most reliable and standard preclinical models, the PDX model in immunodeficient mice (PDX-IM) exerts important effects in drug screening, biomarker development, personalized medicine, co-clinical trials, and immunotherapy. Here, we focus on the development procedures and application of PDX-IM in detail, summarize the implications that the evolution of immunodeficient mice has brought to PDX-IM, and cover the key issues in developing PDX-IM in preclinical studies.

Patient-derived xenograft models in cancer therapy: technologies and applications

Patient-derived xenograft (PDX) models, in which tumor tissues from patients are implanted into immunocompromised or humanized mice, have shown superiority in recapitulating the characteristics of cancer, such as the spatial structure of cancer and the intratumor heterogeneity of cancer. Moreover, PDX models retain the genomic features of patients across different stages, subtypes, and diversified treatment backgrounds. Optimized PDX engraftment procedures and modern technologies such as multi-omics and deep learning have enabled a more comprehensive depiction of the PDX molecular landscape and boosted the utilization of PDX models. These irreplaceable advantages make PDX models an ideal choice in cancer treatment studies, such as preclinical trials of novel drugs, validating novel drug combinations, screening drug-sensitive patients, and exploring drug resistance mechanisms. In this review, we gave an overview of the history of PDX models and the process of PDX model establishment. Subsequently, the review presents the strengths and weaknesses of PDX models and highlights the integration of novel technologies in PDX model research. Finally, we delineated the broad application of PDX models in chemotherapy, targeted therapy, immunotherapy, and other novel therapies.

Footprints: Stamping hallmarks of lung cancer with patient-derived models, from molecular mechanisms to clinical translation

The conventional two-dimensional (2D) tumor cell lines in Petri dishes have played an important role in revealing the molecular biological mechanism of lung cancer. However, they cannot adequately recapitulate the complex biological systems and clinical outcomes of lung cancer. The three-dimensional (3D) cell culture enables the possible 3D cell interactions and the complex 3D systems with co-culture of different cells mimicking the tumor microenvironments (TME). In this regard, patient-derived models, mainly patient-derived tumor xenograft (PDX) and patient-derived organoids discussed hereby, are with higher biological fidelity of lung cancer, and regarded as more faithful preclinical models. The significant Hallmarks of Cancer is believed to be the most comprehensive coverage of current research on tumor biological characteristics. Therefore, this review aims to present and discuss the application of different patient-derived lung cancer models from molecular mechanisms to clinical translation with regards to the dimensions of different hallmarks, and to look to the prospects of these patient-derived lung cancer models.

Targeting RAS Mutant Colorectal Cancer with Dual Inhibition of MEK and CDK4/6

KRAS and NRAS mutations occur in 45% of colorectal cancers, with combined MAPK pathway and CDK4/6 inhibition identified as a potential therapeutic strategy. In the current study, this combinatorial treatment approach was evaluated in a co-clinical trial in patient-derived xenografts (PDX), and safety was established in a clinical trial of binimetinib and palbociclib in patients with metastatic colorectal cancer with RAS mutations. Across 18 PDX models undergoing dual inhibition of MEK and CDK4/6, 60% of tumors regressed, meeting the co-clinical trial primary endpoint. Prolonged duration of response occurred predominantly in TP53 wild-type models. Clinical evaluation of binimetinib and palbociclib in a safety lead-in confirmed safety and provided preliminary evidence of activity. Prolonged treatment in PDX models resulted in feedback activation of receptor tyrosine kinases and acquired resistance, which was reversed with a SHP2 inhibitor. These results highlight the clinical potential of this combination in colorectal cancer, along with the utility of PDX-based co-clinical trial platforms for drug development.

SIGNIFICANCE

This co-clinical trial of combined MEK-CDK4/6 inhibition in RAS mutant colorectal cancer demonstrates therapeutic efficacy in patient-derived xenografts and safety in patients, identifies biomarkers of response, and uncovers targetable mechanisms of resistance.

Zebrafish patient-derived xenograft models predict lymph node involvement and treatment outcome in non-small cell lung cancer

Background

Accurate predictions of tumor dissemination risks and medical treatment outcomes are critical to personalize therapy. Patient-derived xenograft (PDX) models in mice have demonstrated high accuracy in predicting therapeutic outcomes, but methods for predicting tumor invasiveness and early stages of vascular/lymphatic dissemination are still lacking. Here we show that a zebrafish tumor xenograft (ZTX) platform based on implantation of PDX tissue fragments recapitulate both treatment outcome and tumor invasiveness/dissemination in patients, within an assay time of only 3 days.

Methods

Using a panel of 39 non-small cell lung cancer PDX models, we developed a combined mouse-zebrafish PDX platform based on direct implantation of cryopreserved PDX tissue fragments into zebrafish embryos, without the need for pre-culturing or expansion. Clinical proof-of-principle was established by direct implantation of tumor samples from four patients.

Results

The resulting ZTX models responded to Erlotinib and Paclitaxel, with similar potency as in mouse-PDX models and the patients themselves, and resistant tumors similarly failed to respond to these drugs in the ZTX system. Drug response was coupled to elevated expression of EGFR, Mdm2, Ptch1 and Tsc1 (Erlotinib), or Nras and Ptch1 (Paclitaxel) and reduced expression of Egfr, Erbb2 and Foxa (Paclitaxel). Importantly, ZTX models retained the invasive phenotypes of the tumors and predicted lymph node involvement of the patients with 91% sensitivity and 62% specificity, which was superior to clinically used tests. The biopsies from all four patient tested implanted successfully, and treatment outcome and dissemination were quantified for all patients in only 3 days.

Conclusions

We conclude that the ZTX platform provide a fast, accurate, and clinically relevant system for evaluation of treatment outcome and invasion/dissemination of PDX models, providing an attractive platform for combined mouse-zebrafish PDX trials and personalized medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02280-x.

Tumor necrosis factor in lung cancer: Complex roles in biology and resistance to treatment

Tumor necrosis factor (TNF) and its receptors are widely expressed in non-small cell lung cancer (NSCLC). TNF has an established role in inflammation and also plays a key role in inflammation-induced cancer. TNF can induce cell death in cancer cells and has been used as a treatment in certain types of cancer. However, TNF is likely to play an oncogenic role in multiple types of cancer, including NSCLC. TNF is a key activator of the transcription factor NF-κB. NF-κB, in turn, is a key effector of TNF in inflammation-induced cancer. Data from The Cancer Genome Atlas database suggest that TNF could be a biomarker in NSCLC and indicate a complex role for TNF and its receptors in NSCLC. Recent studies have reported that TNF is rapidly upregulated in NSCLC in response to targeted treatment with epidermal growth factor receptor (EGFR) inhibition, and this upregulation leads to NF-κB activation. The TNF upregulation and consequent NF-κB activation play a key role in mediating both primary and secondary resistance to EGFR inhibition in NSCLC, and a combined inhibition of EGFR and TNF can overcome therapeutic resistance in experimental models. TNF may mediate the toxic side effects of immunotherapy and may also modulate resistance to immune checkpoint inhibitors. Drugs inhibiting TNF are widely used for the treatment of various inflammatory and rheumatologic diseases and could be quite useful in combination with targeted therapy of NSCLC and other cancers.

Restoration of circPSMC3 sensitizes gefitinib-resistant esophageal squamous cell carcinoma cells to gefitinib by regulating miR-10a-5p/PTEN axis

Circular RNAs (circRNAs) has been shown to play an important role in the progression of various cancers. However, the function and underlying mechanisms of circRNAs affecting chemotherapy resistance in esophageal squamous cell carcinoma (ESCC) remain largely unknown. In this study, we used gefitinib-resistant (GR) ESCC cells to investigate the function of circPSMC3 and clarify the underlying mechanism in chemotherapy resistance in ESCC. The results suggested that circPSMC3 expression was downregulated, but miR-10a-5p was upregulated in ESCC tissues and cells, as well as in GR ESCC cells. CircPSMC3 overexpression increased the sensitivity of ESCC cells to gefitinib, as indicated by reduced half maximal inhibitory concentration value, increased apoptosis rate and cleaved caspase-3 protein expression. CircPSMC3 directly interacted with miR-10a-5p and inhibited the expression of miR-10a-5p. Phosphatase and tensin homolog (PTEN) was a direct target of miR-10a-5p and circPSMC3 promoted PTEN expression via decreasing miR-10a-5p level. Moreover, the effect of circPSMC3 on resistance of GR ESCC cells to gefitinib was remarkably reduced by restoration of miR-10a-5p and downregultion of PTEN. Taken together, these observations suggested that upregulation of circPSMC3 overcame resistance of GR ESCC cells to gefitinib by modulating the miR-10a-5p/PTEN axis, which provide a new therapeutic strategy for overcoming gefitinib resistance in ESCC.

Genipin suppression of growth and metastasis in hepatocellular carcinoma through blocking activation of STAT-3

BACKGROUND

The signal transducer and activator of transcription-3 (STAT-3) can facilitate cancer progression and metastasis by being constitutively active via various signaling. Abundant evidence has indicated that STAT-3 may be a promising molecular target for cancer treatment.

METHODS

In this study, a dual-luciferase assay-based screening of 537 compounds for STAT-3 inhibitors of hepatocellular carcinoma (HCC) cells was conducted, leading to the identification of genipin. Effects of genipin on HCC were assessed in a patient-derived xenograft nude mice model. Western blotting assay, chromatin immunoprecipitation (ChIP) assay, molecular docking study, tube formation assay, three-dimensional top culture assay, histological examination, and immunofluorescence were utilized to evaluate the regulatory signaling pathway.

RESULTS

Our research demonstrated that genipin suppresses STAT-3 phosphorylation and nuclear translocation, which may be attributed to the binding capacity of this compound to the Src homology-2 (SH2) domain of STAT-3. In addition, the therapeutic effects of genipin in a patient-derived HCC xenograft nude mice model were also demonstrated.

CONCLUSIONS

In conclusion, genipin showed therapeutic potential for HCC treatment by interacting with the SH2-STAT-3 domain and suppressing the activity of STAT-3. In the future, further research is planned to explore the potential role of genipin in combination with chemotherapy or radiotherapy for HCC.

Triptolide inhibits epithelial‑mesenchymal transition and induces apoptosis in gefitinib‑resistant lung cancer cells

The epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), gefitinib, is used widely to treat non-small cell lung cancer (NSCLC) with EGFR-activating mutations. Unfortunately, the acquired drug resistance promoted by epithelial-mesenchymal transition (EMT) markedly limits the clinical effects and remains a major barrier to a cure. Our previous isobaric tags for relative and absolute quantitation-based proteomics analysis revealed that the E-cadherin protein level was markedly upregulated by triptolide (TP). The present study aimed to determine whether TP reverses the gefitinib resistance of human lung cancer cells by regulating EMT. It was revealed that TP combined with gefitinib synergistically inhibited the migration and invasion of lung adenocarcinoma cell line A549; the combination treatment had a significantly better outcome than that of TP and gefitinib alone. Moreover, TP effectively increased the sensitivity of drug resistant A549 cells to gefitinib by upregulating E-cadherin protein expression and downregulating the MMP9, SNAIL, and vimentin expression levels. The dysregulated E-cadherin expression of gefitinib-sensitive cells induced gefitinib resistance, which could be overcome by TP. Finally, TP combined with gefitinib significantly inhibited the growth of xenograft tumors induced using gefitinib-resistant A549 cells, which was associated with EMT reversal and E-cadherin signaling activation in vivo. The present results indicated that the combination of TP and TKIs may be a promising therapeutic strategy to treat patients with NSCLCs harboring EGFR mutations.

Sodium cantharidate targets STAT3 and abrogates EGFR inhibitor resistance in osteosarcoma

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents. Overactive EGFR signaling is frequently seen in osteosarcoma cells, and represents a potential therapeutic target. However, feedback activation of STAT3 after EGFR inhibition is linked to treatment resistance, suggesting that combined EGFR/STAT3 inhibition may be needed to overcome this effect. Cantharidin and its analogues have shown strong anticancer effects, including STAT3 inhibition, in several tumor cells. Therefore, we investigated the effects of sodium cantharidate (SC), either as monotherapy and in combination with the EGFR inhibitor erlotinib, on STAT3 activation and osteosarcoma cell growth. Cell viability, migration, and apoptosis assays were performed in human MG63 and U2OS cells, and MG63 xenografts were generated in nude mice to verify the suppression of tumor growth in vivo. Additionally, western blotting and immunohistochemistry were used to verify the STAT3 and EGFR phosphorylation statuses in xenografts. We found that SC repressed cell viability and migration and induced apoptosis in vitro, while combined SC and erlotinib treatment enhanced osteosarcoma growth suppression by preventing feedback activation of STAT3. These data support further development of cantharidin-based combination therapies for metastatic and recurrent/refractory osteosarcoma.