Molecular mechanisms targeting drug-resistance and metastasis in colorectal cancer:Updates and beyond

Colorectal cancer(CRC)is the third most diagnosed malignancy and a major leading cause of cancer-related deaths worldwide.Despite advances in therapeutic regimens,the number of patients presenting with metastatic CRC(mCRC)is increasing due to resistance to therapy,conferred by a small population of cancer cells,known as cancer stem cells.Targeted therapies have been highly successful in prolonging the overall survival of patients with mCRC.Agents are being developed to target key molecules involved in drug-resistance and metastasis of CRC,and these include vascular endothelial growth factor,epidermal growth factor receptor,human epidermal growth factor receptor-2,mitogen-activated extracellular signal-regulated kinase,in addition to immune checkpoints.Currently,there are several ongoing clinical trials of newly developed targeted agents,which have shown considerable clinical efficacy and have improved the prognosis of patients who do not benefit from conventional chemotherapy.In this review,we highlight recent developments in the use of existing and novel targeted agents against drug-resistant CRC and mCRC.Furthermore,we discuss limitations and challenges associated with targeted therapy and strategies to combat intrinsic and acquired resistance to these therapies,in addition to the importance of implementing better preclinical models and the application of personalized therapy based on predictive biomarkers for treatment selection.

Personalized targeted therapy for esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma continues to heavily burden clinicians worldwide. Researchers have discovered the genomic landscape of esophageal squamous cell carcinoma, which holds promise for an era of personalized oncology care. One of the most pressing problems facing this issue is to improve the understanding of the newly available genomic data, and identify the driver-gene mutations, pathways, and networks. The emergence of a legion of novel targeted agents has generated much hope and hype regarding more potent treatment regimens, but the accuracy of drug selection is still arguable. Other problems, such as cancer heterogeneity, drug resistance, exceptional responders, and side effects, have to be surmounted. Evolving topics in personalized oncology, such as interpretation of genomics data, issues in targeted therapy, research approaches for targeted therapy, and future perspectives, will be discussed in this editorial.

Comparison of Histological, Microbiological, and Molecular Methods in Diagnosis of Patients with TBLN Having Different Anti-TB Treatment Background

Objective The influence of anti-tuberculosis （TB） treatment history on tuberculous lymphadenitis （TBLN） diagnosis is unclear. Therefore, this study aims to evaluate the diagnostic methods, including histology, microbiology, and molecular tests, used for TBLN. Methods In this study, suspected patients with TBLN and having different anti-T8 treatment background were enrolled. All the samples were tested simultaneously by histology, ZiehI-Neelsen （ZN） staining, mycobacterial culture （culture）, Xpert MTB/RIF （xpert）, real-time PCR, and high-resolution melting curve PCR （HRM）. Thereafter, the performance of these methods on samples with different anti-TB treatment background was assessed. Results In our study, 89 patients were prospectively included 82 patients with TBLN and 7 with other diseases. The overall sensitivities of Xpert, real-time PCR, histology, ZN staining, and culture were 86.6%, 69.5%, 58.5%, 43.9%, and 22.0%, respectively. The anti-TB treatment history revealed dramatic influences on the sensitivity of culture （P 〈 0.0001）. In fact, the treatment that lasted over 3 months also influenced the sensitivity of Xpert （P 〈 0.05）. However, the treatment history did not affect the performance of remaining tests （P 〉 0.05）. For rifampicin drug susceptibility test （DST）, the anti-T8 treatment showed only significant influence on the success rate of culture DST （P = 0.001）, but not on those of Xpert and HRM tests （P 〉 0.05）. Conclusion Other tests as welt as culture should be considered for patients with TBLN having retreatment history or over 1-month treatment to avoid false negative results.

EXPRESSION OF MDRII MRP AND LRP GENES IN GASTRIC CARCINOMA AND THEIR CLINICAL SIGNIFICANCE

Objective: To explore the expression of mdrl,multidrug resistance-associated protein (MRP) and lungresistance protein (LRP) genes in human gastric cancerand their clinical significance. Methods: The mdrlmRNA was assayed by RT-PCR, the MRP and LRPwere detected by flow cytometry. Results: The positiverate of mdrl mRNA was 44.4% (12/27), and the meanMRP and LRP expression were independent uponpatient histologic type, nodal involvement, and TNMstage. The mdrl mRNA expression in patients withserosa invasion was 30.0% (6120), much lower than thatwithout serosa invasion (85.7%). Conclusion: Themultidrug resistance cells are present in primary gastriccarcinomas prior to chemotherapy, and analysis of mdrlgene, MRP, LRP may have guiding significance in thetreatment of gastric carcinoma.

ESTABLISHMENT OF INTRAPERITONEAL TRANSPLANTATION MODEL OF CISPLATIN-RESISTANT OVARIAN CARCINOMA CELL IN SCID MICE

Objective： to develop an intraperitoneal transplantation model of human ovarian carcinoma SKOV3/CDDP cell in severe combined immunodeficiency （SCID） mouse and to study its biologic characteristics. Methods： Sixteen qualified C.B 17/SCID mouse were divided into two groups randomly. Human ovarian carcinoma SKOV3 or SKOV3/CDDP cells were injected intraperitoneally into the SCID mouse at the amount of 1×10^7 cells （0.5 mL） per mouse. The behaviors of mice, tumor growth and morphology were analyzed. The expression of cancer antigen 125 （CA125）, GST-π and Topo-Ⅱ were examined by immunohistochemical method. Results： In this experimental study, transplanted tumors are formed in 100% SCID mice in the two groups. The morphology, growth pattern and CA125 secretion of SKOV3/CDDP group were as same as those of SKOV3 group. It shows that the tumors of the two groups kept the characteristics of ovaries serosity papillary adenocarcinoma. Compared with SKOV3 group, the expression of GST-π and Topo-Ⅱ gene in SKOV3/CDDP group were significantly higher （P〈0.05）. Conclusion： An intraperitoneal transplantation model of human ovarian carcinoma SKOV3/CDDP in SCID mice has been developed successfully. It may be an ideal animal model for biotherapy research of ovarian carcinoma as it can simulate the biological behavior of peritoneal metastasis of human ovarian carcinoma and the drug tolerance is maintained.

Evolution from genetics to phenotype： reinterpretation of NSCLC plasticity, heterogeneity, and drug resistance

Lung cancer is the leading cause of cancer-related deaths worldwide. Targeted therapy is beneficial in most cases, but the development of drug resistance stands as an obstacle to good prognosis. Multiple mechanisms were explored such as genetic alterations, activation of bypass signaling, and phenotypic transition. These intrinsic and/or extrinsic dynamic regulations facilitate tumor cell survival in meeting the demands of signaling under different stimulus. This review introduces lung cancer plasticity and heterogeneity and their correlation with drug resistance. While cancer plasticity and heterogeneity play an essential role in the development of drug resistance, the manipulation of them may bring some inspirations to cancer prognosis and treatment. That is to say, lung cancer plasticity and heterogeneity present us with not only challenges but also opportunities.