Pb2+ induces gastrin gene expression by extracellular signal-regulated kinases 1/2 and transcription factor activator protein 1 in human gastric carcinoma cells

The Comparison of the Plasma Levels of the Lead Element in Patients with Gastrointestinal Cancers and Healthy Individuals

Back ground and Aim:

Heavy metals are considered as risk factors in the development of some types of cancers. In this context, the lead (Pb) along with its biological impacts on the human body has raised significant concerns in public health. The aim of this study was to compare the plasma levels of the lead element in patients with gastrointestinal (GI) cancer and healthy subjects to examine whether this element has a role in the susceptibility of cancer.

Methods:

In a case-control study conducted between March 2016 to February 2017, the plasma levels of the lead were assessed. One-hundred patients with upper and lower GI cancers, as well as one-hundered healthy subjects who were age- and sex-matched participated in our study. A classic flame atomic absorption spectroscopy (FAAS) method was employed for the determination of the lead element in plasma levels of all subjects.

Results:

The mean age of patients was 53.8±10.6 years old. The patient group consisted of 51 male and 49 female patients. The results showed that the concentrations of Pb were lower than the defined toxic levels. The comparison of the mean levels of Pb between the case and control groups revealed that there was no statistically significant difference even when the gender, age, and history of smoking were included in the statistical analysis. Our findings showed that the concentration of Pb is significantly associated with the type of cancer (p<0.003) and the location of the tumor (whether upper or lower tract was affected) (p<0.003).

Conclusion:

Lead may contributes to the pathology and progression of GI cancers but we can not conclude that it involved in the causation or susceptibility of healthy individuals to develop GI cancer.

The association between occupational lead exposure and serum levels of selected soluble receptors

The present study was designed to evaluate soluble receptors as potential targets for lead (Pb). Analyses included the serum levels of soluble Vascular Endothelial Growth Factor Receptors 2 (sVEGFR-2), soluble Epidermal Growth Factor Receptor (sEGFR), soluble Human Epidermal Growth Factor 2 (sHER-2/neu), and soluble Interleukin 6 Receptors (sIL-6R) in the groups of chronically and subchronically occupationally exposed workers. The first group consisted of 56 male workers chronically exposed to Pb. The second group (control) comprised 24 male administrative workers. The third group included 36 male workers exposed to Pb for 40 ± 3 days. Examined subjects were employed in the Pb-zinc works to perform periodic maintenance of blast furnaces and production lines. The serum levels of sHER-2/neu and sIL-6R were significantly lower in the group of workers chronically exposed to Pb compared to control values by 45% ( p < 0.05) and 44% ( p < 0.05), respectively. The values of sVEGFR-2 and sEGFR decreased after a subchronic exposure to Pb compared to baseline by 14% ( p < 0.05) and 21% ( p < 0.05), respectively. At the same time, the levels of sIL-6R also decreased by 14% ( p < 0.05). Results of the present study indicated that both chronic and subchronic occupational Pb exposures resulted in decreased levels of several soluble receptors (sVEGFR-2, sEGFR, sHER-2/neu, and sIL-6R), probably due to Pb-induced modulations of the transcription factors and metalloprotease activities, that are necessary for soluble receptor synthesis.

The influence of occupational chronic lead exposure on the levels of selected pro-inflammatory cytokines and angiogenic factors

The aim of the study was to determine the effect of occupational exposure to lead on the blood levels of pro-inflammatory cytokines and selected factors that influence angiogenesis. The study population was divided into two groups. The first group consisted of 56 male workers chronically exposed to lead. The second group (control) was comprised of 24 male administrative workers. The serum levels of interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α) were significantly higher in the group of workers chronically exposed to lead compared to control values by 38%, 68%, and 57%, respectively. Similarly, the values of soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and fibroblast growth factor-basic (FGF-basic) were higher by 19% and 63%, respectively. In the group of workers chronically exposed to lead, there were positive correlations between the levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) and angiogenic factors (VEGF, FGF-basic, sVEGFR-1, and soluble angiopoietin receptor). In the control group, there were no correlations between the levels of the abovementioned parameters. Results of the present study indicate that chronic occupational lead exposure promotes inflammatory processes via induction of pro-inflammatory cytokines, modulates angiogenesis, and elicits interdependencies between the immune response and angiogenic factors.

Advances in Understanding How Heavy Metal Pollution Triggers Gastric Cancer

With the development of industrialization and urbanization, heavy metals contamination has become a major environmental problem. Numerous investigations have revealed an association between heavy metal exposure and the incidence and mortality of gastric cancer. The mechanisms of heavy metals (lead, cadmium, mercury, chromium, and arsenic) contamination leading to gastric cancer are concluded in this review. There are four main potential mechanisms: (1) Heavy metals disrupt the gastric mucosal barrier by decreasing mucosal thickness, mucus content, and basal acid output, thereby affecting the function of E-cadherin and inducing reactive oxygen species (ROS) damage. (2) Heavy metals directly or indirectly induce ROS generation and cause gastric mucosal and DNA lesions, which subsequently alter gene regulation, signal transduction, and cell growth, ultimately leading to carcinogenesis. Exposure to heavy metals also enhances gastric cancer cell invasion and metastasis. (3) Heavy metals inhibit DNA damage repair or cause inefficient lesion repair. (4) Heavy metals may induce other gene abnormalities. In addition, heavy metals can induce the expression of proinflammatory chemokine interleukin-8 (IL-8) and microRNAs, which promotes tumorigenesis. The present review is an effort to underline the human health problem caused by heavy metal with recent development in order to garner a broader perspective.

Cadmium promotes the proliferation of triple-negative breast cancer cells through EGFR-mediated cell cycle regulation

Cadmium (Cd) is a carcinogenic metal which is implicated in breast cancer by epidemiological studies. It is reported to promote breast cancer cell growth in vitro through membrane receptors. The study described here examined Cd-mediated growth of non-metastatic human breast cancer derived cells that lack receptors for estrogen, progesterone, and HER2. Treatment of triple-negative HCC 1937 cells with 0.1-0.5 μM Cd increased cell growth by activation of AKT and ERK. Accelerated cell cycle progression was achieved by increasing the levels of cyclins A, B, and E, as well as those of CDKs 1 and 2. Although triple negative cells lack estrogen receptor, they express high levels of EGFR. Therefore, further studies on HCC 1937 and another triple-negative cell line, HCC 38, were conducted using specific siRNA and an inhibitor of EGFR to determine whether EGFR was responsible for mediating the effect of Cd. The results revealed that in both cell types EGFR was not only activated upon Cd treatment, but was also essential for the downstream activation of AKT and ERK. Based on these observations, it is concluded that, in breast cancer cells lacking estrogen receptor, sub-micromolar concentration of Cd can promote cell proliferation. Furthermore, that EGFR plays a critical role in this process.