Cancer stem cells, also known as tumor initiating cells, are defined as a subset of tumor cells with the capacity to self-renewal and give rise to the differentiated cells that comprise the bulk of the tumor [
3,
5,
6,
9,
13,
45]. CD133 is commonly regarded as a marker of CSCs or TIC in many tumors [
9,
16‐
27]. Recently, CD133 has been identified in more or equal to 50% of NSCLC, colon, gastric and ovarian [
9,
19,
22,
46]. Lung cancer CD133+ cells were able to grow indefinitely as tumor spheres; upon differentiation, lung cancer CD133+ cells acquired the specific lineage markers, while loosed the tumorigenic potential together with CD133 expression [
47]. Furthermore, CD133+ cancer cells were more efficient at forming clones and proliferated more extensively than the CD133- population [
46]. Lung cancer stem cells are resistant to chemotherapeutic drugs, in line with the poor therapeutic effect of conventional chemotherapy on lung cancer patients [
47]. Therefore, anti-CD133 gene-drug conjugates may warrant further evaluation as a molecular therapeutic strategy to eradicate CD133+ cancer cells in lung cancer. To our data, there are no reports about the prognostic significance and correlation between CD133 expression and VM in NSCLC. Using immunohistochemistry, we detect the expression of CD133 in 149 (48.9%) and it is closely related to the worst prognosis of NSCLC. Further research shows that the expression of CD133 may be involved in grade of NSCLC, lymphoid node metastasis and pTNM stages. And the positive expression of CD133 indicates a shorter survival time. Our study is consistent with parts of previous studies in lung carcinoma [
48‐
50]. Another result is that not only normal lung tissue (bronchiolar epithelial cells) but also cancer cell expresses CD133. Although CD133, which is the most accredited, is useful stem cell markers, it is known to be expressed also in non-stem cell populations and play an important role in tumorigenesis [
51]. It has been shown that CD133 is an apical molecule in many normal human tissues and its expression is not restricted to stem cells in pancreatic tissues [
52]. In addition, CD133 has been taken as a prognostic factor of some cancers, such as colon carcinoma, non-small cell lung cancer, hepatocellular carcinoma and cholangiocarcinoma [
48‐
51,
53‐
55]. Our result is similar to the previous studies (including lung and other tissues) [
22,
49,
52,
56]. As the population of CD133+ cells in NSCLC may represent a relatively large portion of cells (up to 48.9%) and only a part of CD133+ cells possesses the abilities of stem cells [
47]. These cancer stem cells after routine chemo- and radio-therapy may lead to tumor recurrence and metastasis through the self-renewal, the multiple differentiating potential and the proliferating aptitude in line with cancer stem cell hypothesis [
57].
Some highly aggressive human tumor cells mimic endothelial cells and form vascular channel-like structures to convey blood and nutrients without the participation of endothelial cells. In other words, the term VM is appropriate to describe the formation of these vascular channels by tumor cells. In the H&E staining, we observe that VM channels are composed of a basement membrane with positive PAS staining and CD34- in the absence of endothelial cells. Based on PAS and CD34 staining, some morphologic patterns of VM including straight lines, arcs, loops, networks and patterns have been described [
58]. In our study, VM is observed in 35.7% (109/305) of NSCLC patients. And we find that VM is associated with grade of tumor, lymph node metastasis and pTNM stages, which are in agreement with previous reports [
59,
60]; further research, we find that the VM-positive-group correlates with the lower survival time, suggests that the existence of VM increases the likelihood of hematogenous metastases and is in inverse proportion to prognosis [
34].
Microvessel density (MVD) is the standard method of measuring tumor angiogenesis and is closely related with tumor growth and postoperative prognosis. So the patients with high scores of MVD indicate early metastasis and short survival [
61,
62]. Our data is consistent with these results. CD133 is not expressed in all tumors, and expressed only a small fraction of the tumor cells in CD133-positive tumors. The niche where CSCs reside may regulate CSCs self-renewal. Vascular niche may regulate CSCs fate. Alternatively, perhaps CD133 is a marker that does not initiate but rather enhances tumor growth, for example, by means of better tumor vascularization [
51]. Our research also shows that CD133, VM and MVD are positively correlated with each other in CD133-positive population, suggesting that CSCs may be related to angiogenesis and vasculogenic mimicry. CSCs have self-renewal properties, multiple differentiating potential and proliferating aptitude. Tumors require a blood and nutrient supply for growth and metastasis. When the diameter of tumor is more than 1 mm3 in volume, tumor can stimulate angiogenesis in order to get adequate blood, the CD133 positive cells may contribute to the formation of capillaries [
62]. But when the blood supplied by neovascularization cannot meet the needs of tumor growth, some CSCs can mimic endothelial cells and form vascular channel-like structures, which is VM [
63]. The microvessel and VM sustain CSCs self-renewal, multiple differentiating potential and proliferating aptitude. The combined detection of CD133, VM and MVD, to some extent, can reflect the biological behavior of NSCLC cells, thus giving the choice of molecular targeting therapy.