Early gastric cancer is associated with a much better prognosis than advanced disease, and strategies to improve prognosis is strictly dependent on earlier detection and accurate diagnosis. Therefore, a label-free, non-invasive imaging technique that allows the precise identification of morphologic changes in early gastric cancer would be of considerable clinical interest. In this study, multiphoton microscopy (MPM) using two-photon excited fluorescence combined with second-harmonic generation was used for the identification of early gastric cancer. This microscope was able to directly reveal improved cellular detail and stromal changes during the development of early gastric cancer. Furthermore, two features were quantified from MPM images to assess the cell change in size and stromal collagen change as gastric lesion developed from normal to early cancer. These results clearly show that multiphoton microscopy can be used to examine early gastric cancer at the cellular level without the need for exogenous contrast agents. This study would be helpful for early diagnosis and treatment of gastric cancer, and may provide the groundwork for further exploration into the application of multiphoton microscopy in clinical practice.

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that target mRNAs for translational repression or cleavage. The present study was conducted to identify differentially expressed miRNAs in primary tumor tissues of rectal carcinoma (RC) that may be associated with heterochrony hepatic metastasis (HHM). Samples were collected exclusively from patients with RC but not colon cancer (CC); Next‑generation high‑throughput sequencing technology and bioinformatics tools were used to profile and analyze small RNAs and their corresponding targets in primary tumor tissues with HHM (n=2) or without metastases (non‑metastatic, NM; n=2). A total of 24 known miRNAs were identified to be differentially expressed (P<0.01; absolute value of log2‑fold change ≥1). Hsa‑let‑7e‑5p exhibited the most significant elevation in tissues with HHM (log2‑fold change=2.62). By combining online informatics resources and previous mRNA sequencing data, it was identified that 54 validated target genes of let‑7e were downregulated in primary tumor tissues with HHM. A number of these target genes have been demonstrated to be directly involved in tumor metastasis (including MYC proto‑oncogene, bHLH transcription factor, high‑mobility group AT‑Hook 2, peptidase inhibitor 3, KIT proto‑oncogene receptor tyrosine kinase, Jun proto‑oncogene, AP‑1 transcription factor subunit and ribonuclease T2), or have physiological associations to immunity (including C‑C motif chemokine receptor 4 and cluster of differentiation 40 ligand) and cellular metabolism (including peroxisome proliferator‑activated receptor γ, coactivator 1 α). Next, 14 target genes were selected for reverse transcription‑quantitative polymerase chain reaction analysis in non‑sequenced samples, and the downregulation of 10 target genes in RC samples with HHM was confirmed. In addition, it was demonstrated that hsa‑let‑7e‑5p stimulated colorectal cancer cell migration in vitro. The miRNA hsa‑let‑7e‑5p may serve as a potential biomarker for rectal carcinoma‑associated HHM, facilitating the identification of patients with RC who are at risk of developing HHM.

Background: Gastrointestinal stromal tumor (GIST) is currently regarded as a potentially malignant tumor, and early diagnosis is the best way to improve its prognosis. Therefore, it will be meaningful to develop a new method for auxiliary diagnosis of this disease.Methods: Here we try out a new means to detect GIST by combining two-photon imaging with automatic image processing strategy.Results: Experimental results show that two-photon microscopy has the ability to label-freely identify the structural characteristics of GIST such as tumor cells, desmoplastic reaction, which are entirely different from those from gastric adenocarcinoma. Moreover, an image processing approach is used to extract eight collagen morphological features from tumor microenvironment and normal muscularis, and statistical analysis demonstrates that there are significant differences in three features—fiber area, density and cross-link density. The three morphological characteristics may be considered as optical imaging biomarkers to differentiate between normal and abnormal tissues.Conclusion: With continued improvement and refinement of this technology, we believe that two-photon microscopy will be an efficient surveillance tool for GIST and lead to better management of this disease.

At present, early diagnosis and treatment is the most effective way to treat early gastrointestinal neuroendocrine tumors. Therefore, we attempted to carry out multiphoton imaging of early neuroendocrine tumors because of its ability to label-free image tissue microstructure at the cellular level. Imaging results show that this imaging technique can quickly identify the histopathological changes in mucosa and submucosa caused by tumor invasion. Furthermore, we performed automatic image analysis on SHG images and extracted two optical diagnostic features-collagen density and average intensity, and also found obvious differences in the density as well as average intensity of collagen fibers in tumor microenvironment using a series of quantitative analysis. These findings may further facilitate the development of multiphoton microscopic imaging technique for clinical use.

There is a close association between tumor response and survival in gastric cancer patients after receiving neoadjuvant treatment. An accurate and rapid assessment of therapeutic efficacy would be helpful for subsequent treatments and individual prognosis. At present, pathological examination is the gold standard for evaluating treatment response, however, it requires additional staining and the process is tedious, labor-intensive, as well as time-consuming. Here, we introduce a label-free imaging technique, two-photon imaging, to evaluate histopathological changes induced by pre-operative therapy, with a focus on assessing tumor regression as well as stromal response. Imaging data show that two-photon imaging allows label-free, rapid visualization of various aspects of pathological alterations in tumor microenvironment such as fibrotic reaction, inflammatory cell infiltration, mucinous response, isolated residual tumor cells. Moreover, a semi-automatic image processing approach is developed to extract the collagen morphological features, and statistical results show that there are significant differences in collagen area, length, width, cross-link space between the gastric cancer tissues with and without treatment. With the advent of a portable, miniaturized two-photon imaging device, we have enough reason to believe that this technique will become as an important auxiliary diagnostic tool in assessing neoadjuvant treatment response and thereby tailoring the most appropriate therapy strategies for the patients.