A modular microfluidic platform to study how fluid shear stress alters estrogen receptor phenotype in ER+ breast cancer cells

Metastatic breast cancer leads to poor prognoses and worse outcomes in patients due to its invasive behavior and poor response to therapy. It is still unclear what biophysical and biochemical factors drive this more aggressive phenotype in metastatic cancer; however recent studies have suggested that exposure to fluid shear stress in the vasculature could cause this. In this study a modular microfluidic platform capable of mimicking the magnitude of fluid shear stress (FSS) found in human vasculature was designed and fabricated. This device provides a platform to evaluate the effects of FSS on MCF-7 cell line, an estrogen receptor positive (ER+) breast cancer cell line, during circulation in the vessels. Elucidation of the effects of FSS on MCF-7 cells was carried out utilizing two approaches: single cell analysis and bulk analysis. For single cell analysis, cells were trapped in a microarray after exiting the serpentine channel and followed by immunostaining on the device (on-chip). Bulk analysis was performed after cells were collected in a microtube at the outlet of the microfluidic serpentine channel for western blotting (off-chip). It was found that cells exposed to an FSS magnitude of 10 dyn/cm2 with a residence time of 60 s enhanced expression of the proliferation marker Ki67 in the MCF-7 cell line at a single cell level. To understand possible mechanisms for enhanced Ki67 expression, on-chip and off-chip analyses were performed for pro-growth and survival pathways ERK, AKT, and JAK/STAT. Results demonstrated that after shearing the cells phosphorylation of p-AKT, p-mTOR, and p-STAT3 were observed. However, there was no change in p-ERK1/2. AKT is a mediator of ER rapid signaling, analysis of phosphorylated ERα was carried out and no significant differences between sheared and non-sheared populations were observed. Taken together these results demonstrate that FSS can increase phosphorylation of proteins associated with a more aggressive phenotype in circulating cancer cells. These findings provide additional information that may help inform why cancer cells located at metastatic sites are usually more aggressive than primary breast cancer cells.

A modular microfluidic platform to study how fluid shear stress alters estrogen receptor phenotype in ER+ breast cancer cells

Metastatic breast cancer leads to poor prognoses and worse outcomes in patients due to its invasive behavior and poor response to therapy. It is still unclear what biophysical and biochemical factors drive this more aggressive phenotype in metastatic cancer; however recent studies have suggested that exposure to fluid shear stress in the vasculature could cause this. In this study a modular microfluidic platform capable of mimicking the magnitude of fluid shear stress (FSS) found in human vasculature was designed and fabricated. This device provides a platform to evaluate the effects of FSS on MCF-7 cell line, a receptor positive (ER+) breast cancer cell line, during circulation in the vessels. Elucidation of the effects of FSS on MCF-7 cells was carried out utilizing two approaches: single cell analysis and bulk analysis. For single cell analysis, cells were trapped in a microarray after exiting the serpentine channel and followed by immunostaining on the device (on-chip). Bulk analysis was performed after cells were collected in a microtube at the outlet of the microfluidic serpentine channel for western blotting (off-chip). It was found that cells exposed to an FSS magnitude of 10 dyn/cm2 with a residence time of 60 seconds enhanced expression of the proliferation marker Ki67 in the MCF-7 cell line at a single cell level. To understand possible mechanisms for enhanced Ki67 expression, on-chip and off-chip analyses were performed for pro-growth and survival pathways ERK, AKT, and JAK/STAT. Results demonstrated that after shearing the cells phosphorylation of p-AKT, p-mTOR, and p-STAT3 were observed. However, there was no change in p-ERK1/2. AKT is a mediator of ER rapid signaling, analysis of phosphorylated ERα was carried out and no significant differences between sheared and non-sheared populations were observed. Taken together these results demonstrate that FSS can increase phosphorylation of proteins associated with a more aggressive phenotype in circulating cancer cells. These findings provide additional information that may help inform why cancer cells located at metastatic sites are usually more aggressive than primary breast cancer cells.

Melanosis in association with metastatic malignant melanoma: report of a case and a unifying concept of pathogenesis

An unusual case of melanosis associated with metastatic malignant melanoma is reported. This was characterized by progressive blue/gray discoloration of the skin of the chest and abdomen in an elderly patient, 1 year after removal of a polypoid malignant melanoma from the right arm. A biopsy of involved skin revealed perivascular aggregates of melanin-laden histiocytes throughout the dermis, the histopathologic hallmark of melanosis. An unusual aspect of the case was the coincidental finding of a tumor embolus within a small dermal vessel, probably a lymphatic. To date, neoplastic melanocytes have been detected in only a small minority of skin biopsies with features of melanosis. This case and a distillation of related information in the literature lead to the conclusion that the essence of melanosis, and the feature that distinguishes this from conventional metastatic melanoma, is the persistent and cumulative dissemination of melanin, via the bloodstream, throughout the body. This in turn leads to progressive pigmentation of all internal organs and the skin. Only continuous access to the circulation by neoplastic melanocytes could explain such a phenomenon. Potential mechanisms by which this could arise are discussed in the context of existing knowledge.

Early experience with transmyocardial laser revascularization

Conventional treatment of coronary artery disease consists of either Coronary Artery Bypass Grafting (CABG), medical therapy or percutaneous transluminal coronary angioplasty (PTCA) or a combination. However, certain group of patients do not even qualify for CABG. Transmyocardial Laser Revascularization (TMR) is a unique new surgical modality specially for that sub group of patient population who have small and diffuse coronary artery disease not suitable for grafting. King Fahad Heart Center initiated its TMR program in February, 1994 and until February, 1996, 100 patients under went the TMR procedure. Eighty-one were males and 19 females with a mean average age of 55 years. Seventy-nine patients had 3 vessel disease (VD) and 66 patients had non-graftable small vessels. Ten patients had left ventricular ejection fraction (LVEF) less than 30%. All the patients underwent a strict protocol of follow-up. The pre and post TMR assessment at six months and 12 months follow-up showed an increase in LVEF at six and 12 months as compared to pre TMR level. The exercise time also increased from a base line level at six months and showed further improvement at 12 months which was statistically significant (p < 0.05) along-with VO2 max, which also showed improvement. Clinically, haemodynamically and symptomatically these patients showed significant improvement and use of anti-anginal drugs (87%) was reduced to minimum. Isotope myocardial perfusion scan on 15 segment viability score showed an improvement from pre TMR level of 33.8 to 45.9 at post TMR 12 months follow up. The surgical mortality in this high risk TMR population was 10%. TMR was found to be a reasonable alternative to medical treatment in patients with angina due to diffuse and or small vessel disease or occluded previous grafts not amenable to CABG.

Relation of a common mutation in methylenetetrahydrofolate reductase to plasma homocysteine and early onset coronary artery disease

OBJECTIVE

In the presence of low serum folate, mutant 5,20-methylenetetrahydrofolate reductase (MTHFR + [A223V/C677T]) in the homozygous state (+/+), may predispose to higher plasma homocysteine (tHct) levels and coronary artery disease (CAD). To determine the impact of this relationship on predisposition to early-onset CAD, we examined the prevalence of the mutation and plasma tHct in patients with early-onset CAD and compared them to patients manifesting CAD later in life.

METHODS

Three hundred patients with history of acute myocardial infarction or angina pectoris and angiographically documented CAD were studied. Patients consisted of two groups: group 1 (G1 = 150 patients) presenting with these findings under age 50; while group 2 (G2 = 150) presented for the first time over age 65 years. Prevalence of the MTHFR+ mutation was assessed by molecular analysis, and plasma tHct and folate were measured. An association of the +/+ genotype with early onset CAD could lead to its higher prevalence in the younger age group.

RESULTS

There was no significant difference in the frequency of the (+/+) genotype between the two groups (G1: 11.3% vs. G2: 11.3%). However, patients with the (+/+) genotype in both groups had higher tHct when plasma folate was below the mean value (G1: p < 0.0001 while G2: p < 0.01).

CONCLUSION

The mutant MTHFR genotype was not found to be a determining factor in early-onset CAD. Higher tHct values were obtained in the older age group, which is expected because other studies have shown that tHct levels increase with age. A significant relation was shown between MTHFR genotype and low folate status yielding high tHct levels in those with the (+/+) genotype. As this relation was seen in both groups, although to a lesser extent in the older G2, it does not explain the underlying cause of early-onset CAD.