Parallelism of DOG1 expression with recurrence risk in gastrointestinal stromal tumors bearing KIT or PDGFRA mutations

Sarco/endoplasmic reticulum calcium ATPase 3 (SERCA3) expression in gastrointestinal stromal tumours

Accurate characterisation of gastrointestinal stromal tumours (GIST) is important for prognosis and the choice of targeted therapies. Histologically the diagnosis relies on positive immunostaining of tumours for KIT (CD117) and DOG1. Here we report that GISTs also abundantly express the type 3 Sarco/Endoplasmic Reticulum Calcium ATPase (SERCA3). SERCA enzymes transport calcium ions from the cytosol into the endoplasmic reticulum and play an important role in regulating the intensity and the periodicity of calcium-induced cell activation. GISTs from various localisations, histological and molecular subtypes or risk categories were intensely immunopositive for SERCA3 with the exception of PDGFRA-mutated cases where expression was high or moderate. Strong SERCA3 expression was observed also in normal and hyperplastic interstitial cells of Cajal. Decreased SERCA3 expression in GIST was exceptionally observed in a zonal pattern, where CD117 staining was similarly decreased, reflecting clonal heterogeneity. In contrast to GIST, SERCA3 immunostaining of spindle cell tumours and other gastrointestinal tumours resembling GIST was negative or weak. In conclusion, SERCA3 immunohistochemistry may be useful for the diagnosis of GIST with high confidence, when used as a third marker in parallel with KIT and DOG1. Moreover, SERCA3 immunopositivity may be particularly helpful in cases with negative or weak KIT or DOG1 staining, a situation that may be encountered de novo, or during the spontaneous or therapy-induced clonal evolution of GIST.

Anaplastic lymphoma kinase expression in PDGFRA-mutated gastrointestinal stromal tumors probably correlates with poor prognosis

BACKGROUND

Anaplastic lymphoma kinase (ALK) overexpression and gene alterations have been detected in several mesenchymal tumors, with significant implications for diagnosis, therapy and prognosis. However, few studies have investigated the correlation between ALK expression status and clinicopathological characteristics in patients with gastrointestinal stromal tumors (GISTs).

METHODS

A total of 506 GIST patients were enrolled. Sanger sequencing was employed to detect c-KIT and PDGFRA gene mutations. The tissue microarray (TMA) technique and immunohistochemistry were employed to identify the ALK (clone: 1A4 and D5F3) expression status in the tumor tissues. The ALK gene variants of IHC-positive cases were analyzed by fluorescence in situ hybridization (FISH) and next-generation sequencing (NGS). The clinicopathological data were analyzed using SPSS Statistics 26.0.

RESULTS

Among the 506 GIST patients, the c-KIT mutation accounted for 84.2% (426/506), followed by PDGFRA mutation (10.3%, 52/506), while the wild-type accounted for the least (5.5%, 28/506). ALK-positive expression was detected in PDGFRA-mutant GISTs (7.7%, 4/52) but negative for c-KIT-mutant or wild-type GISTs by IHC. Four ALK IHC-positive patients were all male. The tumors all occurred outside the stomach. The predominant patterns of growth were epithelioid (2/4), spindle (1/4), and mixed type (1/4). They were all identified as high-risk classification according to the National Institutes of Health (NIH) classification. Aberrant ALK mutations were not identified by DNA-based NGS except in one of the 4 cases with amplification by FISH.

CONCLUSION

Our study revealed 7.7% (4/52) of ALK expression in PDGFRA-mutant GISTs, indicating that molecular tests were required to rule out the possibility of PDGFRA-mutant GISTs when encountering ALK-positive mesenchymal tumors with CD117-negative or weakly positive in immunohistochemical staining.

High level of ANO1 promotes pancreatic cancer growth in concert with oncogenic KRAS

BACKGROUND

Anoctamin-1 (ANO1) was identified as an unfavorable prognostic marker in pancreatic cancer. However, the exact implication of ANO1 in pancreatic cancer is still poorly understood. Here we investigated the effect of ANO1 in pancreatic cancer progression under the context of oncogenic KRAS, aiming at finding a new therapeutic target.

METHODS

Knockdown and overexpression of oncogenic KRAS as well as ANO1 in PDAC cell lines were performed by lentivirus infection. Cell proliferation and migration assay, RNA seq analysis were performed in PDAC cells bearing different status of ANO1 and KRAS. In vivo mice model was used to investigate the xenograft tumor growth with different status of KRAS and ANO1.

RESULTS

Our results showed that ANO1 expression level is elevated in poorly differentiated cancer cells. Overexpression of ANO1 in PDAC cancer cells was found to promote cancer cell proliferation in vitro and in vivo, which synergized with the introduction of oncogenic KRAS. Consistently, knockdown of ANO1 expression was found to suppress cancer growth in vitro and in vivo. RNA seq analysis revealed that the observed synergistic cancer-promoting effect from ANO1 and oncogenic KRAS is likely due to concurrent activating key genes involved in lipid metabolism including HMGCS1.

CONCLUSION

The outcome from our study suggests that ANO1 plays an important role in promoting pancreatic cancer development, especially at the presence of oncogenic KRAS. Considering the prevalence of KRAS mutation in pancreatic cancer patients, suppression ANO1 may represent a potential effective therapeutic measure in pancreatic cancer treatment.

Gastric Pouch Gastrointestinal Stromal Tumour Post-Roux-en-Y Gastric Bypass: A First Reported Case

Gastric gastrointestinal stromal tumour is an extremely rare condition to occur after bariatric surgery. To the authors’ knowledge, only two cases of gastric gastrointestinal stromal tumours after Roux-en-Y gastric bypass have been reported in the medical literature, both occurring in the excluded gastric remnant. Herein, the authors report the third case of gastric gastrointestinal stromal tumour post-Roux-en-Y gastric bypass, and the first case to occur in the gastric pouch, which was managed surgically by laparoscopic resection. From here, combining the observations of clinicians treating and following up patients post-bariatric surgery in an international database will be beneficial to patients, and aid in development of surveillance guidelines.

The lymphatic vascular system: much more than just a sewer

Almost 400 years after the (re)discovery of the lymphatic vascular system (LVS) by Gaspare Aselli (Asellius G. De lactibus, sive lacteis venis, quarto vasorum mesaraicorum genere, novo invento Gasparis Asellii Cremo. Dissertatio. (MDCXXIIX), Milan; 1628.), structure, function, development and evolution of this so-called 'second' vascular system are still enigmatic. Interest in the LVS was low because it was (and is) hardly visible, and its diseases are not as life-threatening as those of the blood vascular system. It is not uncommon for patients with lymphedema to be told that yes, they can live with it. Usually, the functions of the LVS are discussed in terms of fluid homeostasis, uptake of chylomicrons from the gut, and immune cell circulation. However, the broad molecular equipment of lymphatic endothelial cells suggests that they possess many more functions, which are also reflected in the pathophysiology of the system. With some specific exceptions, lymphatics develop in all organs. Although basic structure and function are the same regardless their position in the body wall or the internal organs, there are important site-specific characteristics. We discuss common structure and function of lymphatics; and point to important functions for hyaluronan turn-over, salt balance, coagulation, extracellular matrix production, adipose tissue development and potential appetite regulation, and the influence of hypoxia on the regulation of these functions. Differences with respect to the embryonic origin and molecular equipment between somatic and splanchnic lymphatics are discussed with a side-view on the phylogeny of the LVS. The functions of the lymphatic vasculature are much broader than generally thought, and lymphatic research will have many interesting and surprising aspects to offer in the future.

The analysis of prognostic factors of primary small intestinal gastrointestinal stromal tumors with R0 resection: A single-center retrospective study

OBJECTIVE

We aim to assess factors that affect overall survival in patients with primary small intestinal gastrointestinal stromal tumors (GISTs) who had undergone R0 resection.

METHOD

A retrospective analysis reviewed the data of 82 consecutive confirmed GIST patients at a single medical center in China from January 2012 to June 2020. The survival curve was estimated using the Kaplan-Meier method, and independent prognostic factors were confirmed using the Cox regression model.

RESULTS

A total of 82 patients were included in the study: 42 men and 40 women, the mean age was 59 years old (23-83 years old). Tumors were commonly found in the jejunum (46.3%), ileum (20.7%), and duodenum (32.9%). The median tumor size was 6.0 cm (range: 1.0-15.0 cm). The number of mitoses per one 50 high-power field was used to define the mitotic rates. In our present study, 56 patients presented a mitotic rate ≤5 (68.3%) and 26 patients showed a rate >5 (31.7%) at the time of diagnosis. All patients accepted tumor resection without lymph node resection. The positivity rate was 97.6% for CD117, 96.3% for delay of germination 1, 65.9% for CD34, 6.1% for S-100, and 59.8% for smooth muscle actin using immunohistochemistry. Tumor size, tumor rupture, Ki67 index, mitotic index, and postoperative imatinib were independent prognostic factors for small intestinal GISTs.

CONCLUSIONS

In this study, larger tumor size, high Ki67 index, high mitotic index, the occurrence of tumor rupture, and use of imatinib were independent unfavorable prognostic indicators.

DOG1 expression is common in human tumors: A tissue microarray study on more than 15,000 tissue samples

DOG1 (Discovered on GIST1) is a voltage-gated calcium-activated chloride and bicarbonate channel that is highly expressed in interstitial cells of Cajal and in gastrointestinal stromal tumors (GIST) derived from Cajal cells. To systematically determine in what tumor entities and normal tissue types DOG1 may be further expressed, a tissue microarray (TMA) containing 15,965 samples from 121 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry. DOG1 immunostaining was found in 67 tumor types including GIST (95.7%), esophageal squamous cell carcinoma (31.9%), pancreatic ductal adenocarcinoma (33.6%), adenocarcinoma of the Papilla Vateri (20%), squamous cell carcinoma of the vulva (15.8%) and the oral cavity (15.3%), mucinous ovarian cancer (15.3%), esophageal adenocarcinoma (12.5%), endometrioid endometrial cancer (12.1%), neuroendocrine carcinoma of the colon (11.1%) and diffuse gastric adenocarcinoma (11%). Low level-DOG1 immunostaining was seen in 17 additional tumor entities. DOG1 expression was unrelated to histopathological parameters of tumor aggressiveness and/or patient prognosis in cancers of the breast (n = 1002), urinary bladder (975), ovary (469), endometrium (173), stomach (233), and thyroid gland (512). High DOG1 expression was linked to estrogen receptor expression in breast cancer (p < 0.0001) and absence of HPV infection in squamous cell carcinomas (p = 0.0008). In conclusion, our data identify several tumor entities that can show DOG1 expression levels at similar levels as in GIST. Although DOG1 is tightly linked to a diagnosis of GIST in spindle cell tumors, the differential diagnosis is much broader in DOG1 positive epithelioid neoplasms.

Expression of DOG1 in peripheral blood cells of patients with gastrointestinal stromal tumor

BACKGROUND AND STUDY AIMS

The diagnosis and surveillance of gastrointestinal stromal tumor (GIST) rely on pathology and immunochemistry (IHC), making it complicated and invasive. Noninvasive and convenient biomarkers of this disease need to be explored. The high specificity and sensitivity of IHC in detecting GIST 1 (DOG1) in biopsy indicate that it is also expressed in circulating tumor cells of the blood and may be an ideal biomarker for GIST. This aimed to detect the expression of DOG1 in peripheral blood cells (PBCs) and determine the relationship between DOG1 expression and clinical factors.

PATIENTS AND METHODS

A total of 45 patients with GIST and 46 healthy controls (HCs) were recruited from the Second Affiliated Hospital of Nanchang University between December 2015 and June 2018. PBCs were isolated from peripheral venous blood by density gradient centrifugation. RNA was extracted from PBCs, and DOG1 mRNA was detected by quantitative reverse transcription polymerase chain reaction. DOG1 mRNA expression between GIST and HC was compared, and the relationship between clinical factors and DOG1 was also analyzed.

RESULTS

DOG1 mRNA expression in PBCs was significantly higher in patients with GIST than that in HCs (3.326 [1.942-5.328] versus 0.744 [0.269-1.087], p < 0.01). The specificity and sensitivity were 88.9% and 89.1%, respectively (AUC = 0.912). Tumor diameter and risk of aggressive behavior were correlated with DOG1 expression, and other clinical factors (sex, age, location, number of phase-splitting cells, Ki-67 index, metastatic status) did not show any relationship with DOG1 expression. However, clinical factors, including tumor diameter and risk grade, were not independent factors in DOG1 expression when multivariate analysis was conducted.

CONCLUSION

DOG1 expressions were significantly higher in patients with GIST than that in HCs. Tumor diameter and risk classification correlated with DOG1 expression but were not independent factors. DOG1 in PBCs is a promising noninvasive biomarker for GIST.

Expression of TMEM16A in Colorectal Cancer and Its Correlation With Clinical and Pathological Parameters

TMEM16A is a recently identified calcium-activated chloride channel (CaCC) and its overexpression contributes to tumorigenesis and progression in several human malignancies. However, little is known about expression of TMEM16A and its clinical significance in colorectal cancer (CRC). TMEM16A mRNA expression was determined by quantitative real time-PCR (qRT-PCR) in 67 CRC tissues and 24 para-carcinoma tissues. TMEM16A protein expression was performed by immunohistochemistry in 80 CRC tissues. The correlation between TMEM16A expression and clinicopathological parameters, and known genes and proteins involved in CRC was analyzed. The results showed that TMEM16A mRNA expression was frequently detected in 51 CRC tissues (76%), whereas TMEM16A protein expression was determined at a relatively lower frequency (26%). TMEM16A mRNA expression in tumor tissues was higher than its expression in normal para-carcinoma tissues (P < 0.05). TMEM16A mRNA expression was significantly correlated with TNM stage (p = 0.039) and status of lymph node metastasis (p = 0.047). In addition, there was a strong positive correlation between TMEM16A mRNA expression and MSH2 protein. More importantly, TMEM16A protein expression was positively associated with KRAS mutation, and negatively correlated with mutant p53 protein. Logistic regression analysis demonstrated that TMEM16A mRNA expression was an important independent predictive factor of lymph node metastasis (OR = 16.38, CI: 1.91–140.27, p = 0.01). TMEM16A mRNA and protein expression was not significantly related with patient survival. Our findings provide original evidence demonstrating TMEM16A mRNA expression can be a novel predictive marker of lymph node metastasis and TMEM16A protein expression may be an important regulator of tumor proliferation and metastasis in CRC.

Evaluation of Ki67 Index in Endoscopic Ultrasound-Guided Fine Needle Aspiration Samples for the Assessment of Malignancy Risk in Gastric Gastrointestinal Stromal Tumors

BACKGROUND

The risk of malignancy in resected gastrointestinal stromal tumors (GISTs) depends on tumor size, location, and mitotic index. Reportedly, the Ki67 index has a prognostic value in resected GISTs. We aimed to analyze the accuracy of endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) samples with reference to Ki67 index, using surgical specimens as the gold standard.

METHODS

Fifty-five patients who underwent EUS-FNA followed by surgical resection for gastric GISTs were retrospectively analyzed. Patients' age and sex; tumors' size and location; mitotic index, cell type, cellularity, pleomorphism, presence of ulceration, hemorrhage, necrosis, mucosal or serosal invasion, growth pattern, and Ki67 index based on pathology were investigated.

RESULTS

Location in fundus, ulceration, hemorrhage, mucosal invasion, and Ki67 index in surgical specimens were significant in predicting high-risk groups (p < 0.05) on univariate analysis. Frequency of bleeding (p = 0.034) and the Ki67 index (p = 0.018) were the only independent significant factors in multivariate analysis. The optimal cutoff level of Ki67 was 5%, with 88.2% sensitivity and 52.8% specificity (p = 0.021). The mean Ki67 index was lower in EUS-FNA samples than in surgical specimens (2% [1-15] versus 10% [1-70], p = 0.001). The rank correlation coefficient value of Ki67 was 0.199 (p = 0.362) between EUS-FNA and surgical samples and showed no reliability for EUS-FNA samples.

CONCLUSION

The Ki67 index in resected specimens correlated with high-risk GISTs, although it had no additive value to the current criteria. The Ki67 index in EUS-guided FNA samples is not a reliable marker of proliferation in GISTs.

Gastrointestinal stromal tumor of the excluded stomach after Roux-en-Y gastric bypass: A case report and literature review

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This is the second reported case of GIST post-RYGB.

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GISTs generally present good prognosis after surgical resection.

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The case reported after RYGB did not present the patient follow-up.

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The case reported after gastric banding presented recurrence 3 years after resection.

Background

Gastric cancer is an extremely rare condition to occur after bariatric surgery, and most of the reported cases are adenocarcinomas. Regarding gastrointestinal stromal tumors (GISTs), there are only two reported cases occurring after bariatric surgery (one after gastric banding and the other following Roux-en-Y gastric bypass (RYGB)).

Case presentation

A 48-year-old woman with previous history of obesity and type 2 diabetes, treated with a Roux-en-Y gastric bypass 2 years earlier, was referred to our center due to complains of diffuse abdominal pain and distension associated with asthenia. Magnetic resonance imaging showed a cystic-solid mass located in the right hypochondrium, measuring 19.5 × 13.5 × 16 cm, suggesting the diagnosis of a retroperitoneal tumor. Based on these findings, a laparotomy, evidencing that the larger cystic-solid tumor was originating from the excluded stomach post-RYGB. The gastrectomy of the excluded stomach was performed aside with a conventional cholecystectomy. Histopathology and immunohistochemistry confirmed to be a gastric GIST with epithelioid cells. Currently, 12 months after surgery, the patient presents no signs of recurrence.

Conclusion

This is the second case of gastric GIST occurring after RYGB to be reported in the literature.

Development of an Ewing sarcoma cell line with resistance to EWS‑FLI1 inhibitor YK‑4‑279

Despite Ewing sarcoma (ES) being the second most common pediatric malignancy of bone and soft tissue, few novel therapeutic approaches have been introduced over the past few decades. ES contains a pathognomonic chromosomal translocation that leads to a fusion protein between EWSR1 and an ets family member, most often FLI1. EWS‑FLI1 is the most common type of fusion protein and is a well‑vetted therapeutic target. A small molecule inhibitor of EWS‑FLI1, YK‑4‑279 (YK) was developed with the intention to serve as a targeted therapy option for patients with ES. The present study investigated resistance mechanisms by developing an ES cell line specifically resistant to YK. The ES cell line A4573 was treated with YK to create resistant cells by long term continuous exposure. The results revealed that resistance in A4573 was robust and sustainable, with a >27‑fold increase in IC50 lasting up to 16 weeks in the absence of the compound. Resistant ES cells were still sensitive to standard of care drugs, including doxorubicin, vincristine and etoposide, which may be valuable in future combination treatments in the clinic. Resistant ES cells revealed an increased expression of CD99. RNA sequencing and qPCR validation of resistant ES cells confirmed an increased expression of ANO1, BRSK2 and IGSF21, and a reduced expression of COL24A1, PRSS23 and RAB38 genes. A functional association between these genes and mechanism of resistance remains to be investigated. The present study created a cell line to investigate YK resistance.

The multifaceted role of TMEM16A in cancer

The calcium-activated chloride channel TMEM16A is intimately linked to cancers. Over decades, TMEM16A over-expression and contribution to prognosis have been widely studied for multiple cancers strengthening the idea that TMEM16A could be a valuable biomarker and a promising therapeutic target. Surprisingly, from the survey of the literature, it appears that TMEM16A has been involved in multiple cancer-related functions and a large number of molecular targets of TMEM16A have been proposed. Thus, TMEM16A appears to be an ion channel with a multifaceted role in cancers. In this review, we summarize the latest development regarding TMEM16A contribution to cancers. We will survey TMEM16A contribution in cancer prognosis, the origins of its over-expression in cancer cells, the multiple biological functions and molecular pathways regulated by TMEM16A. Then, we will consider the question regarding the molecular mechanism of TMEM16A in cancers and the possible basis for the multifaceted role of TMEM16A in cancers.

Identification of candidate target genes for endometrial cancer, such as ANO1, using weighted gene co-expression network analysis

Network-based systems biology has become an important method for analysis of high-throughput gene expression data and gene function mining. The aim of the present study was to implement a weighted gene co-expression network analysis to screen genes that were significantly correlated with the clinical phenotype of endometrial cancer based on data from The Cancer Genome Atlas. By using the function ‘pickSoftThreshold’ in R software, the optimum soft thresholding power was determined to be 4. Subsequently, a total of 2,414 expressed genes were identified among 19,791 genes from 506 samples, which were divided into 24 modules according to the different expression patterns. After analyzing the correlation between the gene expression in these 24 modules and the clinical phenotype of endometrial cancer, the anoctamin 1 (ANO1) gene was selected for further analysis. The Chi-squared test indicated that ANO1 was significantly associated with age (P=0.047), histological type (P<0.001), clinical stage (P<0.001), pathological grade (P<0.001) and positive peritoneal washing (P=0.001) of endometrial carcinoma. Kaplan-Meier survival analysis revealed that a high level of ANO1 was significantly associated with a good prognosis for endometrial cancer patients. Univariate and multivariate Cox regression analysis indicated that ANO1 is an independent prognostic factor in endometrial cancer. Further characterization of the most relevant module containing ANO1 with the database for annotation, visualization and integrated discovery tool suggested that ANO1 is involved in various pathways, including metabolic pathways. The present study suggests that ANO1 may be a potential marker for good prognosis in endometrial cancer.

Prognostic factors of primary gastrointestinal stromal tumors: a cohort study based on high-volume centers

Objective

We aimed to evaluate the clinicopathologic characteristics, immunohistochemical expression and prognostic factors of patients with primary gastrointestinal stromal tumors (GISTs).

Methods

Data from 2,570 consecutive GIST patients from four medical centers in China (January 2001-December 2015) were reviewed. Survival curves were constructed by the Kaplan-Meier method, and Cox regression models were used to identify independent prognostic factors.

Results

Of the included patients, 1,375 (53.5%) were male, and the patient age range was 18 to 95 (median, 58) years. The tumors were mostly found in the stomach (64.5%), small intestine (25.1%) and colorectal region (5.1%). At the time of diagnosis, the median tumor size was 4.0 (range: 0.1-55.0) cm, and the median mitotic index per 50 high power fields (HPFs) was 3 (range: 0-254). Of the 2,168 resected patients, 2,009 (92.7%) received curative resection. According to the modified National Institutes of Health (NIH) classification, 21.9%, 28.9%, 14.1% and 35.1% were very low-, low-, intermediate- and high-risk tumors, respectively. The rate of positivity was 96.4% for c-Kit, 87.1% for CD34, 96.9% for delay of germination 1 (DOG-1), 8.0% for S-100, 31.0% for smooth muscle actin (SMA) and 5.1% for desmin. However, the prognostic value of each was limited. Multivariate analysis showed that age, tumor size, mitotic index, tumor site, occurrence of curative resection and postoperative imatinib were independent prognostic factors. Furthermore, we found that high-risk patients benefited significantly from postoperative imatinib (P<0.001), whereas intermediate-risk patients did not (P=0.954).

Conclusions

Age, tumor size, mitotic index, tumor site, occurrence of curative resection and postoperative imatinib were independent prognostic factors in patients with GISTs. Moreover, determining whether intermediate-risk patients can benefit from adjuvant imatinib would be of considerable interest in future studies.

Loss of c-KIT expression in thyroid cancer cells

Papillary thyroid carcinoma is the most frequent histologic type of thyroid tumor. Few studies investigated the role of c-KIT expression in thyroid tumors, suggesting a role for this receptor and its ligand in differentiation and growth control of thyroid epithelium and a receptor loss following malignant transformation. We investigated and correlated c-KIT expression levels and two known markers of thyrocytes differentiation, PAX8 and TTF-1, in malignant and benign cytological thyroid samples. Moreover, we performed functional studies on human papillary thyroid carcinoma cell line to associated c-KIT expression to thyrocytes differentiation and tumor proliferation. c-KIT and PAX8 expression resulted higher in benign samples compared to the malignant ones, and the expression levels of these two genes were significantly correlated to each other. We also observed that c-KIT overexpression led to an increase of PAX8 expression level together with a decrease of proliferation. Furthermore, c-KIT overexpressing cells showed a regression of typical morphological features of malignancy. Taken together these results suggest that c-KIT could be involved in the differentiation of thyroid cells and in tumor progression.

Morphological and Molecular Characterization of Human Dermal Lymphatic Collectors

Millions of patients suffer from lymphedema worldwide. Supporting the contractility of lymphatic collectors is an attractive target for pharmacological therapy of lymphedema. However, lymphatics have mostly been studied in animals, while the cellular and molecular characteristics of human lymphatic collectors are largely unknown. We studied epifascial lymphatic collectors of the thigh, which were isolated for autologous transplantations. Our immunohistological studies identify additional markers for LECs (vimentin, CCBE1). We show and confirm differences between initial and collecting lymphatics concerning the markers ESAM1, D2-40 and LYVE-1. Our transmission electron microscopic studies reveal two types of smooth muscle cells (SMCs) in the media of the collectors with dark and light cytoplasm. We observed vasa vasorum in the media of the largest collectors, as well as interstitial Cajal-like cells, which are highly ramified cells with long processes, caveolae, and lacking a basal lamina. They are in close contact with SMCs, which possess multiple caveolae at the contact sites. Immunohistologically we identified such cells with antibodies against vimentin and PDGFRα, but not CD34 and cKIT. With Next Generation Sequencing we searched for highly expressed genes in the media of lymphatic collectors, and found therapeutic targets, suitable for acceleration of lymphatic contractility, such as neuropeptide Y receptors 1, and 5; tachykinin receptors 1, and 2; purinergic receptors P2RX1, and 6, P2RY12, 13, and 14; 5-hydroxytryptamine receptors HTR2B, and 3C; and adrenoceptors α2A,B,C. Our studies represent the first comprehensive characterization of human epifascial lymphatic collectors, as a prerequisite for diagnosis and therapy.